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8,100 | Suppose that you have an abstract for a scientific paper: lisa will use quadrant photoreceivers as front - end devices for the phasemeter measuring the motion of drag - free test masses in both angular orientation and separation .
we have set up a laboratory testbed for the characterization of photoreceivers . some of the limiting noise sources have been identified and their contribution has been either measured or derived from the measured data .
we have built a photoreceiver with a 0.5 mm diameter quadrant photodiode with an equivalent input current noise of better than @xmath0 below 20mhz and a 3db bandwidth of 34mhz . .
And you have already written the first three sentences of the full article: the laser interferometer space antenna ( lisa ) is a planned gravitational wave observatory in the frequency range of 0.1mhz100mhz that consists of three spacecraft separated by 5 million km in a nearly equilateral triangle whose center follows the earth in a heliocentric orbit with an orbital phase offset of 20 degrees .
gravitational waves will be detected as distance fluctuations between test masses moving along geodetic trajectories that are located in different spacecraft .
lisa will require low power ultra - low noise photoreceivers for precision inter - spacecraft heterodyne laser interferometry ..
Please generate the next two sentences of the article | quadrant photoreceivers will be used to measure the test mass motion with a sensitivity of 8@xmath1 in angular orientation and 10@xmath2 in displacement over the frequency range of 0.1mhz100mhz@xcite .
the laser beam at the transmitting spacecraft will have a diameter of approximately 40 cm and an output laser power at the telescope of the order of 1w . |
8,101 | Suppose that you have an abstract for a scientific paper: seesaw models with a slightly broken lepton number symmetry can explain small neutrino masses , and allow for low - scale leptogenesis .
we make a thorough analysis of leptogenesis within the simplest model with two right - handed ( rh ) neutrinos ( or with @xmath0 decoupled ) .
we obtain a semi - analytical formula for the final asymmetry in both supersymmetric and non - supersymmetric cases with a simple dependence on each parameter .
the low - energy parameters factorize from the high - energy ones , and the high - energy phase must be non - zero . the role of the pmns phases is carefully studied . moreover , we find that the breaking parameter in the yukawa coupling matrix must be relatively large , @xmath1 for normal and @xmath2 for inverted hierarchy
. therefore , leptogenesis in our simple model is incompatible with rh neutrino signals at future colliders or sizable lepton - flavor violation .
the other breaking parameter , @xmath3 , which appears in the rh neutrino mass matrix , can be much smaller , and actually needs to be so in order to have low - scale leptogenesis .
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And you have already written the first three sentences of the full article: leptogenesis @xcite is one of the most attractive scenarios to explain the origin of the observed matter - antimatter asymmetry of the universe .
it follows from the seesaw mechanism @xcite , which gives a natural and simple explanation to the small neutrino masses observed in neutrino experiments , and relies on the conversion of a lepton asymmetry to a baryon asymmetry thanks to the non - perturbative sphaleron processes @xcite . for a recent review on leptogenesis ,
see @xcite ..
Please generate the next two sentences of the article | if neutrinos are massive majorana particles , then lepton number must be violated . since neutrino masses are observed experimentally to be tiny , a slightly broken lepton number symmetry , e.g. a global @xmath4 , could provide the explanation . in this case ,
small neutrino masses are not explained by a ` seesaw ' mechanism , but rather by a cancellation mechanism @xcite . |
8,102 | Suppose that you have an abstract for a scientific paper: we compute radiative corrections in five and six dimensional field theories , using winding modes in mixed momentum - coordinate space .
this method provides a simple way of finding uv divergencies , finite corrections and localized terms when the space is compactified on orbifolds . as an application we compute the finite piece of scalar masses , the logarithmic contributions to the couplings and the effect of localized parallel and perpendicular kinetic terms .
we apply it to get a two loop effective potential that can stabilize large extra dimensions . .
And you have already written the first three sentences of the full article: the standard model is not a fundamental theory and there have been many proposals to go beyond it .
it is expected that a field theory with extra dimensions arises as the low energy limit of a fundamental string theory .
for this reason extra dimensions are a common feature of any theory valid at high energies ..
Please generate the next two sentences of the article | almost all problems of particle physics have been reformulated in this context giving new possibilities .
in particular , physics of large extra dimensions can provide solutions to the hierarchy problem @xcite , @xcite and new mechanism of symmetry breaking @xcite , that can be tested in the next high energy experiments . |
8,103 | Suppose that you have an abstract for a scientific paper: we propose a method for measuring entangled vibronic quantum states of a trapped atom .
it is based on the nonlinear dynamics of the system that appears by resonantly driving a weak electronic transition .
the proposed technique allows the direct sampling of a wigner - function matrix , displaying all knowable information on the quantum correlations of the motional and electronic degrees of freedom of the atom .
it opens novel possibilities for testing fundamental predictions of the quantum theory concerning interaction phenomena . .
And you have already written the first three sentences of the full article: entanglement is one of the most striking aspects of quantum mechanics @xcite . in classical physics ,
two interacting systems retain their individuality during the interaction process and become completely independent of each other after their coupling has been switched off . by way of contrast ,
quantum theory predicts a completely different behaviour of interacting systems ..
Please generate the next two sentences of the article | when two quantum systems are brought to interact , their identities become in the course of time more and more entangled , so that a state - vector description of each system is in general precluded .
they build an entangled composite system , whose state - vector can not be separated into a product of the states of the subsystems . |
8,104 | Suppose that you have an abstract for a scientific paper: we have investigated the structural and dynamical properties of triaxial stellar systems whose surface brightness profiles follow the @xmath0 luminosity law extending the analysis of ciotti ( 1991 ) who explored the properties of spherical @xmath0 systems . a new analytical expression that accurately reproduces the spatial ( i.e. deprojected ) luminosity density profiles ( error less than 0.1% )
is presented for detailed modelling of the srsic family of luminosity profiles .
we evaluate both the symmetric and the non axisymmetric components of the gravitational potential and force and compute the torques as a function of position . _ for a given triaxiality , stellar systems with smaller values of @xmath1 have a greater non axisymmetric gravitational field component_. we also explore the strength of the non axisymmetric forces produced by bulges with differing @xmath1 and triaxiality on systems having a range of bulge to disc ratios . the increasing disc to bulge ratio with increasing galaxy type ( decreasing @xmath1 ) is found to heavily reduce the amplitude of the non axisymmetric terms , and therefore reduce the possibility that triaxial bulges in late
type systems may be the mechanism or perturbation for non symmetric structures in the disc . using seeing
convolved @xmath0bulge plus exponential disc fits to the k band data from a sample of 80 nearby disc galaxies , we probe the relations between galaxy type , srsic index @xmath1 and the bulge to disc luminosity ratio .
these relations are shown to be primarily a consequence of the relation between @xmath1 and the total bulge luminosity . in the k
band , the trend of decreasing bulge to disc luminosity ratio along the spiral hubble sequence is predominantly , although not entirely , a consequence of the change in the total bulge luminosity ; the trend between the total disc luminosity and hubble type is much weaker .
= = = = = = = = # 1 # 1 # 1 # 1 @mathgroup@group @mathgroup@normal@groupeurmn....
And you have already written the first three sentences of the full article: as the quality of photometric data has improved over the years ( largely due to the use of ccds ) , the applicability of a fitting - function which can account for variations in the curvature of a light profile has been demonstrated for elliptical galaxies ( capaccioli 1987 , 1989 ; davies et al .
1988 ; caon , capacciolli & donofrio 1993 ; young & currie 1994 ; graham et al .
1996 ) , and for the bulges of spiral galaxies ( andredakis , peletier & balcells 1995 ; seigar & james 1998 ; moriondo , giovanardi & hunt 1998 ; khosroshahi , wadadekar & kembhavi 2000 ; prieto et al . 2001 ; graham 2001 ; mllenhoff & heidt 2001 ) ..
Please generate the next two sentences of the article | these systems are not universally described with either an exponential profile or an @xmath2 law ( de vaucouleurs 1948 , 1959 ) , but rather a continuous range of light profile shapes exist which are well described by the srsic ( 1968 ) @xmath0 model . in ellipticals , the shape parameter @xmath1 from the srsic model is strongly correlated with the other global properties derived independently of the @xmath0 model , such as : total luminosity and effective radius ( caon et al.1993 ; young & currie 1994 , 1995 ; jerjen & bingelli 1997 ; trujillo , graham & caon 2001 ) , central velocity dispersion ( graham , trujillo & caon 2001 ) and also central supermassive black hole mass ( graham et al.2001 ) .
additionaly , the spiral hubble type has been shown to correlate with the bulge index @xmath1 such that early type spiral galaxy bulges have larger values of @xmath1 than late type spiral galaxy bulges ( andredakis et al . |
8,105 | Suppose that you have an abstract for a scientific paper: we study the energy flux carried by acoustic waves excited by convective motions at sub - photospheric levels .
the analysis of high - resolution spectropolarimetric data taken with imax / sunrise provides a total energy flux of @xmath064007700wm@xmath1 at a height of @xmath0250 km in the 5.210mhz range , i.e. at least twice the largest energy flux found in previous works .
our estimate lies within a factor of 2 of the energy flux needed to balance radiative losses from the chromosphere according to @xcite and revives interest in acoustic waves for transporting energy to the chromosphere .
the acoustic flux is mainly found in the intergranular lanes but also in small rapidly - evolving granules and at the bright borders , forming dark dots and lanes of splitting granules . .
And you have already written the first three sentences of the full article: the long - running debate on the heating of chromospheric layers by acoustic waves is fed by the fact that even the largest measured energy fluxes ( found by bello gonzlez et al.2009,2010 ) are nearly an order of magnitude smaller than the amount needed to balance the chromospheric energy losses of 14000wm@xmath1 @xcite .
bello gonzlez et al . found an acoustic energy flux of @xmath03000 wm@xmath1 at 250 km and of @xmath02000 wm@xmath1 at 500 km from velocity fluctuations measured from narrow - band ( fwhm=1.8pm ) data at @xmath004 spatial resolution on the fei lines at 557.6 nm and 543.4 nm , formed in mid - photospheric and low - chromospheric layers , respectively .
this is a factor of 46 larger than that given by @xcite and @xcite from intensity fluctuations in continuum bands at 160 nm ( of @xmath01@xmath2 spatial resolution ) and in caiih formed at heights of 430 km and 200 km , respectively ..
Please generate the next two sentences of the article | we refer the reader to @xcite for a detailed introduction to the acoustic - wave heating debate .
+ in this contribution , we present results on acoustic waves from data taken in the fei line at 525.02 nm with the highest spatial resolution considered so far . |
8,106 | Suppose that you have an abstract for a scientific paper: recent evidence on the metal content of the high - redshift ly@xmath0 forest seen in quasar spectra suggests that an early generation of galaxies enriched the intergalactic medium ( igm ) at @xmath1 .
we calculate the number of supernovae that need to have taken place to produce the observed metallicity .
the progenitor stars of the supernovae should have emitted @xmath2 ionizing photons for each baryon in the universe , i.e. , more than enough to ionize the igm .
we calculate that the rate of these supernovae is such that about one of them should be observable at any time per square arc minute .
their fluxes are , of course , extremely faint : at @xmath3 , the peak magnitude should be @xmath4 with a duration of @xmath5 1 year .
however , these supernovae should still be the brightest objects in the universe beyond some redshift , because the earliest galaxies should form before quasars and they should have very low mass , so their luminosities should be much lower than that of a supernova .
we also show that , under the assumption of a standard initial mass function , a significant fraction of the stars in the galactic halo should have formed in the early galaxies that reionized and enriched the igm , and which later must have merged with our galaxy .
these stars should have a more extended radial distribution than the observed halo stars . .
And you have already written the first three sentences of the full article: ever since the discovery of the first high - redshift quasar ( schmidt 1965 ) , quasars have maintained their title as the objects with the highest known redshift ; the present record holder is a quasar at @xmath6 ( schmidt , schneider , & gunn 1991 ) . nevertheless , the highest known redshifts of galaxies have followed closely behind , with bright radio galaxies having been found up to @xmath7 ( lacy et al . 1994 ; rawlings et al .
1996 ) ; more recently , galaxies with high star formation rates have been identified from interstellar absorption lines at @xmath8 to 3 ( steidel et al . 1996 ) and from the ly@xmath0 emission line at @xmath9 ( hu & mcmahon 1996 ) .
in fact , if quasars are related to supermassive black holes that formed in the centers of high - redshift galaxies , we should expect that many galaxies already existed before the first quasars appeared . in any ` bottom - up ' theory where the observed structure in the universe forms by hierarchical gravitational collapse , and the primordial density fluctuations extend to sufficiently small scales ,.
Please generate the next two sentences of the article | the first galaxies to form must have had much smaller masses than the present galaxies .
the first stars should have formed in systems with velocity dispersions of @xmath10 or lower , corresponding to the lowest temperatures ( @xmath11 k ) that allow cooling and dissipation of the gas by atomic processes ( systems with even lower virial temperatures can cool and dissipate through molecular hydrogen , but this cooling process should be suppressed by photodissociation of the molecules after emission of a number of uv photons that is much smaller than that needed to reionize the universe ; see haiman , rees , & loeb 1996 ) . |
8,107 | Suppose that you have an abstract for a scientific paper: we recapitulate the latest results on the class of the simplest @xmath0 grand unified models in which the gut - scale symmetry breaking is triggered by an adjoint higgs representation .
we argue that the minimal survival approximation traditionally used in the gut- and seesaw - scale estimates tends to be blind to very interesting parts of the parameter space in which some of the intermediate - scale states necessary for non - supersymmetric unification of the sm gauge couplings can be as light as to leave their imprints in the tev domain .
the stringent minimal - survival - based estimates of the @xmath1 scale are shown to be relaxed by as much as four orders of magnitude , thus admitting for a consistent implementation of the standard seesaw mechanism even without excessive fine - tuning implied by the previous studies .
the prospects of the minimal renormalizable @xmath0 gut as a potential candidate for a well - calculable theory of proton decay are discussed in brief .
address = ahep group , instituto de fsica corpuscular
c.s.i.c./universitat de valncia , edificio de institutos de paterna , apartado 22085 , e 46071 valncia , spain address = infn , sezione di trieste , sissa , via bonomea 265 , 34136 trieste , italy address = institut fr theoretische teilchenphysik , karlsruhe institute of technology ( kit ) , d-76128 karlsruhe , germany .
And you have already written the first three sentences of the full article: with the next generation of large - volume proton - decay searches and neutrino experiments currently in the r&d phase ( in particular , lbne @xcite , lena @xcite and hyper - k @xcite ) there are good prospects to push the current lower bounds on the proton lifetime to the unprecedented level of @xmath2 years . on the theory side ,
the new information may be , at least in principle , used for further testing of the grand unification paradigm ; however , this would require a very good grip on the proton lifetime predictions supplied by specific guts . unfortunately , the quality of the existing estimates is rather limited even in very simple scenarios , see figure [ estimates ] , and it is namely due to the low accuracy of the leading - order methods used in most of the relevant calculations . on the other hand , consistent next - to - leading - order ( nlo ) proton lifetime estimates
are parametrically more difficult : first , at the nlo level , the gut scale @xmath3 must be determined at two - loops ; this , however , requires a detailed understanding of the one - loop theory spectrum ..
Please generate the next two sentences of the article | second , the flavour structure of the relevant baryon - number - violating ( bnv ) currents must be constrained by the existing data to a maximum attainable degree .
third , one has to account for several classes of almost irreducible uncertainties related to the planck - scale physics ( such as , e.g. , gravity smearing of the gauge unification pattern @xcite ) which are often comparable to the nlo effects . a simple illustration of the typical size of uncertainties in proton lifetime estimates obtained in some of the most popular su(5 ) and so(10 ) guts . |
8,108 | Suppose that you have an abstract for a scientific paper: we report an experimental verification of conformal mapping with kitchen aluminum foil . this experiment can be reproduced in any laboratory by undergraduate students and it is therefore an ideal experiment to introduce the concept of conformal mapping .
the original problem was the distribution of the electric potential in a very long plate .
the correct theoretical prediction was recently derived by a. czarnecki @xcite . .
And you have already written the first three sentences of the full article: the initial problem is part of the collection of the moscow institute of physics and technology @xcite .
a voltage @xmath0 is applied to the corners a and b of a semi - infinite long metallic ruler as shown in fig .
[ fig : ruler ] ) . is applied between a and b. between c and d the voltage @xmath1 is being measured . ].
Please generate the next two sentences of the article | the question is : when one measures the voltage difference @xmath1 between c and d , how does the voltage difference behave further down the ruler ? assuming that the thickness of the ruler can be neglected , this can be reduced to a two - dimensional problem .
a. czarnecki derived the correct solution to this problem conformal mapping @xcite . in this tutorial , we present the experimental verification of these new calculations . |
8,109 | Suppose that you have an abstract for a scientific paper: we show that the inclusion of long distance effect , expected in strong interactions , through a nonextensive thermodynamical approach is able to explain the experimental distribution of the transverse momentum of the hadrons with respect to the jet axis ( @xmath0 ) @xmath1 reaction .
the observed deviation from the exponential behavior , predicted by the boltzmann - gibbs thermodynamical treatment , is automatically recovered by the nonextensive tsallis statistics used here .
we fitted the observed @xmath0 spectrum in the range of 14 gev to 161 gev and obtained , besides a good fit , the theoretical important fact that the temperature becomes independent of the primary energy .
xxxxxxxxxxxxxxxxxx= high energy ; hadroproduction ; fireball ; statistical models .
+ 24.10.pa , 13.65.+i , 13.60.hb , .
And you have already written the first three sentences of the full article: the global structure of multiple hadroproduction in annihilation , has been well understood with remarkable results concerning the total cross section and angular distribution calculations .
perturbative quantum electrodynamics and perturbative quantum chromodynamics provide a good description of the initial process involving short distances @xmath2 quark - antiquark ( @xmath3 ) and @xmath2 quark - antiquark - gluon ( @xmath4 ) interactions , main responsible for the global characteristics of this kind of process .
the quarks produced off - shell initialize a cascade of several quarks and gluons with complex interactions themselves ..
Please generate the next two sentences of the article | this stage is in general described in probabilistic terms , based on leading - log quantum chromodynamics approximation .
the outgoing colored partons are transformed into color singlet hadrons through the soft hadronization process , forming a jet of particles traveling approximately in the initial parton direction . however , hadronization require the quantum chromodynamics in the soft regime , where the coupling constant become large and there is no easy way to understand it from first principles . for |
8,110 | Suppose that you have an abstract for a scientific paper: we present new _
chandra _ x - ray observations and detailed astrometry of the field of the type ia supernova 2007on , for which the detection of a likely progenitor in archival _ chandra _ data was recently reported .
no source is detected in the new _ chandra _ images , taken six weeks after optical maximum .
we calculate a 9099% probability that any x - ray source near the position of the supernova ( sn ) is fainter than in the pre - outburst images , depending on the choice of aperture , which supports the identification of the archival x - ray source with the sn .
detailed astrometry of the x - ray and new optical images , however , gives an offset between the supernova and the measured x - ray source position of [email protected]@xmath1 .
extensive simulations show that the probability of finding an offset of this magnitude is @xmath21% , equal to the ( trial - corrected ) probability of a chance alignment with any x - ray source in the field .
this casts doubt on the identification of the x - ray source with the progenitor , although the scenario in which at least some of the observed x - rays are connected to the supernova may be the _
least unlikely _ based on all available data .
after a brief review of the auxiliary evidence , we conclude that only future x - ray observations can shed further light on the proposed connection between the x - ray source and the progenitor of sn 2007on , and thus whether an accreting white dwarf scenario is truly favoured for this sn ia .
[ firstpage ] supernovae binaries : close white dwarfs x - ray : binaries .
And you have already written the first three sentences of the full article: type ia supernovae are thought to be the result of thermonuclear explosion of carbon - oxygen white dwarfs as they reach or exceed the chandrasekhar mass limit ( see , e.g. , @xcite for reviews ) .
broadly speaking , there are two main classes of models : the accreting models , in which the white dwarf more or less steadily accretes matter from a ( hydrogen - rich ) companion star @xcite , and the merging models , in which two white dwarfs coalesce under the influence of angular momentum losses due to the emission of gravitational waves @xcite .
deciding which of the scenarios contribute to the observed sn ia rates is difficult from a purely theoretical point of view ..
Please generate the next two sentences of the article | one may , however , expect observable differences between the accreting and merging scenarios . in an effort to constrain the progenitor scenario for individual sne ia
, @xcite recently started a search for progenitor detections of newly reported , nearby sne ia in archival _ chandra x - ray observatory _ |
8,111 | Suppose that you have an abstract for a scientific paper: we consider the construction and classification of some new mathematical objects , called ergodic spatial stationary processes , on locally compact abelian groups , which provide a natural and very general setting for studying diffraction and the famous inverse problems associated with it . in particular we can construct complete families of solutions to the inverse problem from any given pure point measure that is chosen to be the diffraction . in this case these processes can be classified by the dual of the group of relators based on the set of bragg peaks , and this gives a solution to the homometry problem for pure point diffraction .
an ergodic spatial stationary process consists of a measure theoretical dynamical system and a mapping linking it with the ambient space in which diffracting density is supposed to exist . after introducing these processes
we study their general properties and link pure point diffraction to almost periodicity . given a pure point measure we show how to construct from it and a given set of phases a corresponding ergodic spatial stationary process .
in fact we do this in two separate ways , each of which sheds its own light on the nature of the problem .
the first construction can be seen as an elaboration of the halmos
von neumann theorem , lifted from the domain of dynamical systems to that of stationary processes .
the second is a gelfand construction obtained by defining a suitable banach algebra out of the putative eigenfunctions of the desired dynamics . .
And you have already written the first three sentences of the full article: this paper is concerned with mathematics of diffraction .
more specifically we are interested in the famous inverse problem for diffraction : given something that is putatively the diffraction of something , what are all the somethings that could have produced this diffraction .
diffraction has been a mainstay in crystallography for almost a hundred years . with the proliferation of extraordinary new materials with varying degrees of order and disorder.
Please generate the next two sentences of the article | , the importance of diffraction in revealing internal structure continues to be central .
the precision , complexity , and variety of modern diffraction images is striking , see for instance the recent review article @xcite . nonetheless , in spite of many advances , |
8,112 | Suppose that you have an abstract for a scientific paper: a mathematical model for tissue growth is considered .
this model describes the dynamics of the density of cells due to pressure forces and proliferation .
it is known that such cell population model converges at the incompressible limit towards a hele - shaw type free boundary problem .
the novelty of this work is to impose a non - overlapping constraint .
this constraint is important to be satisfied in many applications .
one way to guarantee this non - overlapping constraint is to choose a singular pressure law .
the aim of this paper is to prove that , although the pressure law has a singularity , the incompressible limit leads to the same hele - shaw free boundary problem .
nonlinear parabolic equation ; incompressible limit ; free boundary problem ; tissue growth modelling . 35k55 ; 76d27 ; 92c50 . .
And you have already written the first three sentences of the full article: mathematical models are now commonly used in the study of growth of cell tissue . for instance , a wide literature is now available on the study of the tumor growth through mathematical modeling and numerical simulations @xcite . in such models , we may distinguish two kinds of description : either they describe the dynamics of cell population density ( see e.g. @xcite ) , or they consider the geometric motion of the tissue through a free boundary problem of hele - shaw type ( see e.g. @xcite ) .
recently the link between both descriptions has been investigated from a mathematical point of view thanks to an incompressible limit @xcite . in this paper , we depart from the simplest cell population model as proposed in @xcite . in this model the dynamics of the cell density is driven by pressure forces and cell multiplication .
more precisely , let us denote by @xmath0 the cell density depending on time @xmath1 and position @xmath2 , and by @xmath3 the mechanical pressure ..
Please generate the next two sentences of the article | the mechanical pressure depends only on the cell density and is given by a state law @xmath4 .
cell proliferation is modelled by a pressure - limited growth function denoted @xmath5 . |
8,113 | Suppose that you have an abstract for a scientific paper: chaos , deterministic dynamical systems , lyapunov exponents , mean square displacement , euclidean extension we describe a new test for determining whether a given deterministic dynamical system is chaotic or nonchaotic .
in contrast to the usual method of computing the maximal lyapunov exponent , our method is applied directly to the time series data and does not require phase space reconstruction . moreover
, the dimension of the dynamical system and the form of the underlying equations is irrelevant .
the input is the time series data and the output is @xmath0 or @xmath1 depending on whether the dynamics is non - chaotic or chaotic .
the test is universally applicable to any deterministic dynamical system , in particular to ordinary and partial differential equations , and to maps .
our diagnostic is the real valued function @xmath2 where @xmath3 is an observable on the underlying dynamics @xmath4 and @xmath5 .
the constant @xmath6 is fixed arbitrarily .
we define the mean - square - displacement @xmath7 for @xmath8 and set @xmath9 . using recent developments in ergodic theory
, we argue that typically @xmath10 signifying nonchaotic dynamics or @xmath11 signifying chaotic dynamics .
[ firstpage ] .
And you have already written the first three sentences of the full article: the usual test of whether a deterministic dynamical system is chaotic or nonchaotic is the calculation of the largest lyapunov exponent @xmath12 .
a positive largest lyapunov exponent indicates chaos : if @xmath13 , then nearby trajectories separate exponentially and if @xmath14 , then nearby trajectories stay close to each other .
this approach has been widely used for dynamical systems whose equations are known ( abarbanel _ et al ..
Please generate the next two sentences of the article | _ 1993 ; eckmann _ et al .
_ 1986 ; parker & chua 1989 ) . |
8,114 | Suppose that you have an abstract for a scientific paper: the soft x - ray telescope ( sxt ) on board yohkoh revealed that the ejection of x - ray emitting plasmoid is sometimes observed in a solar flare .
it was found that the ejected plasmoid is strongly accelerated during a peak in the hard x - ray emission of the flare . in this paper
we present an examination of the goes x 2.3 class flare that occurred at 14:51 ut on 2000 november 24 . in the sxt images we found `` multiple '' plasmoid ejections with velocities in the range of 250 - 1500 km s@xmath0 , which showed blob - like or loop - like structures .
furthermore , we also found that each plasmoid ejection is associated with an impulsive burst of hard x - ray emission .
although some correlation between plasmoid ejection and hard x - ray emission has been discussed previously , our observation shows similar behavior for multiple plasmoid ejection such that each plasmoid ejection occurs during the strong energy release of the solar flare . as a result of temperature - emission measure analysis of such plasmoids
, it was revealed that the apparent velocities and kinetic energies of the plasmoid ejections show a correlation with the peak intensities in the hard x - ray emissions . .
And you have already written the first three sentences of the full article: the soft x - ray telescope ( sxt ; * ? ? ? * ) on board yohkoh @xcite revealed that a soft x - ray emitting plasma ejection , or plasmoid ejection , is sometimes observed in solar flares ( e.g. * ? ? ? * ) .
it was also found that the plasmoids show blob - like or loop - like shapes and that the strong acceleration of the plasmoid ejection occurs during the peak time of the hard x - ray emission @xcite .
their ejection velocities are typically several hundred km s@xmath0 and the ejected plasma is heated to more than 10 mk before the onset of the ejection @xcite ..
Please generate the next two sentences of the article | they often start to rise up gradually a few tens of minutes before the onset of a hard x - ray burst and are then strongly accelerated just before or at the impulsive phase of the flare .
a similar kinetic evolution is also seen in the case of coronal mass ejections ( cmes ; * ? ? ? |
8,115 | Suppose that you have an abstract for a scientific paper: force fluctuations in granular materials are investigated .
a continuum equation is derived starting from a discrete model proposed in the literature . the influence of boundary conditions is investigated . for periodic boundary conditions the average weight
is found to increase linearly with depth while it saturates to a constant value for absorbing boundary conditions , which models the existence of walls .
the scale dependencies of the saturation weight , the saturation depth and the average squared fluctuations are obtained .
the analytical results are compared with previous works and with numerical simulations in one dimension . 2 .
And you have already written the first three sentences of the full article: a wide variety of technical processes involve the storage and transport of granular materials .
on the other hand , granular materials have very unusual properties which have intrigued researches in physics over recent years @xcite . of great importance
is the characterization of stress fluctuations in dry granular materials ..
Please generate the next two sentences of the article | optical measurements in two and three dimensional @xcite arrays of granular materials have showed that the stress in packed granular materials is not distributed uniformly inside the medium , but is concentrated along `` chains '' .
further experiments dealing with force fluctuations in the bottom of relative small containers have shown an exponential distribution of vertical forces ( weight ) @xmath0 @xcite . |
8,116 | Suppose that you have an abstract for a scientific paper: we propose using the self energy defined for the electron removal green s function . starting from the electron removal
green s function , we obtained expressions for the removal self energy @xmath0(*k*,@xmath1 ) that are applicable for non - quasiparticle photoemission spectral functions from a single band system .
our method does not assume momentum independence and produces the self energy in the full * k*-@xmath1 space .
the method is applied to the angle resolved photoemission from ca@xmath2cuo@xmath2cl@xmath2 and the result is found to be compatible with the self energy value from the peak width of sharp features .
the self energy is found to be only weakly * k*-dependent .
in addition , the im@xmath3 shows a maximum at around 1 ev where the high energy kink is located . .
And you have already written the first three sentences of the full article: photoemission lineshape contains information on the many - body interactions in the solid under study .
one notable example is the kink structure in the angle resolved photoemission(arpes ) spectral function from a metal at the bosonic mode energy due to electron - bosonic mode coupling@xcite . in this regard ,
the kink structures at near 70 mev found in the arpes spectral functions from cuprate high temperature superconductors ( htscs ) have been a hot topic during the last several years as it may provide a clue on what mediates the pairing in the htsc@xcite ..
Please generate the next two sentences of the article | it is still under debate whether the kink is caused by phonons or magnetic excitations .
in addition to the kink near 70mev , an anomalous high energy kink structure from insulating cuprate ca@xmath2cuo@xmath2cl@xmath2 ( ccoc ) was recently reported@xcite . |
8,117 | Suppose that you have an abstract for a scientific paper: according to a recent conjecture , isospectral objects have different nodal count sequences @xcite .
we study generalized laplacians on discrete graphs , and use them to construct the first non - trivial counter - examples to this conjecture .
+ in addition , these examples demonstrate a surprising connection between isospectral discrete and quantum graphs . .
And you have already written the first three sentences of the full article: nodal structures on continuous manifolds have been investigated ever since the days of chladni .
his work was experimental and involved the observation of nodal lines on vibrating plates .
his research was resumed on a more rigorous footing by the pioneering works of sturm @xcite , courant @xcite and pleijel @xcite ..
Please generate the next two sentences of the article | + in recent years a surge of research has begun on inverse nodal problems , i.e. learning about the geometry of a system by observing its nodal features @xcite .
this research follows what is already known for many years in the regime of inverse spectral problems : one can deduce geometrical information about a system by observing its spectrum . + a key question in the framework of inverse spectral theory |
8,118 | Suppose that you have an abstract for a scientific paper: the alice collaboration measures the production of low - mass dielectrons in pp , p pb and pb pb collisions at the lhc .
the main detectors used in the analyses are the inner tracking system , time projection chamber and time - of - flight detector , all located around mid - rapidity .
the production of virtual photons relative to the inclusive yield in pp collisions is determined by analyzing the dielectron excess with respect to the expected hadronic sources .
the direct photon cross section is then calculated and found to be in agreement with nlo pqcd calculations .
results from the invariant mass analysis in p
pb collisions show an overall agreement between data and hadronic cocktail . in pb
pb collisions , uncorrected background - subtracted yields have been extracted in two centrality classes . a feasibility study for lhc
run 3 after the alice upgrade indicates the possibility for a future measurement of the early effective temperature . .
And you have already written the first three sentences of the full article: the measurement of electron - positron pairs ( dielectrons ) in the low invariant mass region allows studying the vacuum and in - medium properties of light vector mesons .
additionally , low - mass dielectrons are produced by internal conversion of virtual direct photons .
they are excellent probes to study all collision stages , since they pass through the created medium almost unaffected . to quantify modifications of the dielectron production in heavy - ion collisions , measurements in pp collisions serve as a reference , while the analysis of p - a collisions allows disentangling cold from hot nuclear matter effects . in alice @xcite at the lhc.
Please generate the next two sentences of the article | , dielectron measurements are performed using the central barrel detectors around mid - rapidity .
electrons can be identified via their specific energy loss in the inner tracking system ( its ) and the time projection chamber ( tpc ) , combined with time - of - flight information from the tof detector @xcite . in this proceedings |
8,119 | Suppose that you have an abstract for a scientific paper: the status of our work on binary classical cepheid systems in the large magellanic cloud is presented .
we report on results from our follow up of two eclipsing binary cepheids ogle - lmc - cep-0227 and ogle - lmc - cep-1812 . here
we presented for the first time confirmation that a third cepheid ogle - lmc - cep-2532 is a true eclipsing binary cepheid with a period of 800 days .
two other very good candidates for eclipsing binaries detected during ogle - iv survey are also discussed . .
And you have already written the first three sentences of the full article: the eclipsing binary systems containing classical cepheids are very rare .
although we know tens of binary cepheids in our galaxy ( e.g. evans @xcite ) , none is an eclipsing system .
however extensive search for variability in microlensing surveys in magellanic clouds resulted in reporting of reliable eclipsing binary candidates : a double cepheid system macho 05:21:54.8 - 69:21:50 ( alcock @xcite ) , first overtone cepheid ogle lmc sc16 119952 ( udalski @xcite ) and two fundamental mode cepheids ogle - lmc - cep-0227 and ogle - lmc - cep-1812 ( soszyski @xcite ) ..
Please generate the next two sentences of the article | deriving fundamental physical parameters of classical cepheids is an important task regarding their great significance for extragalactic distance scale . as part of the araucaria project we made
follow up of candidate eclipsing binaries in the large magellanic cloud ( lmc ) . |
8,120 | Suppose that you have an abstract for a scientific paper: we report on the low and moderate @xmath0 nucleon spin structure measurements done at jefferson lab , examining specifically the inclusive program .
we discuss what the data teach us about quark confinement and the emergence of the effective hadronic degrees of freedom from the fundamental partonic ones .
we show how this experimental program has reached its goal by providing a precise mapping at low , intermediate and moderately high @xmath0 which has followed in many advances , e.g. , with chiral perturbation theory .
another example of a recent advance imputable to the jlab spin data is the improved understanding of @xmath1 at low energy , which allowed light
front holographic qcd , an approximation to non - perturbative qcd , to derive the hadron spectrum from @xmath2 . .
And you have already written the first three sentences of the full article: there are many reasons to study the spin of the nucleon .
an ingenuous reason is that it is interesting in itself : we are curious to know how the spin of the nucleon emerges from its constituents , i.e. , how the spins and orbital angular momenta of the quarks and gluons combine together into the spin 1/2 of the nucleon .
we have also more practical reasons : spin degrees of freedom provide additional tests to theories ..
Please generate the next two sentences of the article | hence , studying spin observables provides a more complete study of the fundamental force ruling the nucleon structure , the strong force , of which the accepted gauge theory is quantum chromodynamics ( qcd ) .
we can also learn about important emergent properties of qcd , such as the mechanism of confinement , how the effective hadronic degrees of freedom stem from the fundamental partonic ones , or how well non - perturbative methods , e.g. , chiral perturbation theory ( @xmath3pt ) , lattice gauge theory or the gravity - gauge ( ads / cft ) correspondence , describe the strong force in its low energy domain . |
8,121 | Suppose that you have an abstract for a scientific paper: azimuthal asymmetries measured in unpolarized semi - inclusive deep inelastic scattering bring important information on the inner structure of the nucleons , and can be used both to estimate the average quark transverse momentum @xmath0 and to access the so - far unmeasured boer - mulders functions .
compass results using part of the 2004 data collected with a @xmath1lid target and a 160 gev @xmath2 beam are presented separately for positive and negative hadrons . .
And you have already written the first three sentences of the full article: after years of study to understand how the nucleon spin originates from the constituent partons , an exhaustive answer is still missing .
moreover , while a lot of information has been gathered concerning the longitudinal structure of a fast moving nucleon ( with respect to its direction of motion ) , very little is known about the transverse structure . in recent years these aspects have raised a lot of interest and after important theoretical developments and experimental findings , transverse spin and transverse momentum @xmath0 of the quarks are by now considered as fundamental ingredients in the description of the hadron structure .
spin-@xmath0 correlations give rise to various observables in hard hadronic processes such as the azimuthal asymmetries seen both in unpolarized or transversely polarized semi - inclusive deep - inelastic scattering ( sidis ) , and led to the introduction of transverse momentum dependent ( tmd ) parton distribution functions ( pdf ) and fragmentation functions ( ff ) . among these functions of special interest.
Please generate the next two sentences of the article | are the sivers functions @xmath3
@xcite , which describe an azimuthal asymmetry in the parton distributions inside a transversely polarized nucleon , and by their chirally - odd partner @xmath4 , the boer - mulders functions @xcite , describing the transverse parton polarization inside an unpolarized hadron , and generating azimuthal asymmetries in unpolarized sidis . |
8,122 | Suppose that you have an abstract for a scientific paper: the problem of recognizing ( non-)markovianity of a quantum dynamics is revisited through analyzing quantum correlations .
we argue that instantaneously - vanishing quantum discord provides a necessary and sufficient condition for markovianity of a quantum map .
this is used to introduce a measure of non - markovianity .
this measure , however , requires demanding knowledge about the system and the environment . by using a quantum correlation monogamy property and an ancillary system ,
we propose a simplified measure with less requirements .
non - markovianity is thereby decided by quantum state tomography of the system and the ancilla . .
And you have already written the first three sentences of the full article: real quantum systems are inevitably open because of interaction with their ambient environment . as a result ,
information , in principle , can leak into the environment , and may be fed back later in a different form into the system @xcite .
this scenario makes accurate description of the related dynamics difficult @xcite , because one often has no much information / control about / over the environment unless , e.g. , the environment can be controllably engineered @xcite ..
Please generate the next two sentences of the article | nevertheless , under some specific ( ideal ) conditions , such as weak coupling with a memoryless environment and born - markov approximation , the underlying system evolution can be well described by a quantum _ markovian _ dynamical equation @xcite ( see also ref .
@xcite for an alternative derivation ) . |
8,123 | Suppose that you have an abstract for a scientific paper: we examine the problem of optimal design in the context of filtering multiple random walks . specifically , we define the steady state e - optimal design criterion and show that the underlying optimization problem leads to a second order cone program .
the developed methodology is applied to tracking network flow volumes using sampled data , where the design variable corresponds to controlling the sampling rate .
the optimal design is numerically compared to a myopic and a naive strategy .
finally , we relate our work to the general problem of steady state optimal design for state space models . . .
And you have already written the first three sentences of the full article: consider a wide area computer network such as the one in figure [ geant ] .
a _ flow _ is defined as all traffic with common origin and destination nodes .
monitoring flow volumes plays an important role in network management tasks , such as capacity planning by tracking demands and forecasting traffic , identifying failures together with their causes and impact , detecting malicious activity and configuring routing protocols [ @xcite , ] ..
Please generate the next two sentences of the article | these flow volumes have been observed to exhibit complicated structure , as seen in figure [ flowvols ] .
for example , the highly aggregated flows usually have diurnal patterns [ figure [ flowvols](a ) ] , while lighter flows can be extremely noisy [ figure [ flowvols](b ) ] . network traffic is carried on packets that can be observed ( and sampled ) at router interfaces , henceforth called _ |
8,124 | Suppose that you have an abstract for a scientific paper: in this note , we announce a complete classification of stability of periodic roll - wave solutions of the viscous shallow - water equations , from their onset at froude number @xmath0 up to the infinite - froude limit . for intermediate froude numbers ,
we obtain numerically a particularly simple power - law relation between @xmath1 and the boundaries of the region of stable periods , that appears potentially useful in hydraulic engineering applications . in the asymptotic regime @xmath2 ( onset ) , we provide an analytic expression of the stability boundaries whereas in the limit @xmath3 , we show that roll - waves are always unstable . .
And you have already written the first three sentences of the full article: in this note , we announce the classification in @xcite of spectral stability of roll - wave solutions of the `` viscous '' st . venant equations for inclined shallow - water flow , taking into account drag and viscosity . written in nondimensional eulerian form , the shallow water equations for a thin film down an incline are @xmath4 where @xmath1 is the froude number and @xmath5 is the inverse of the reynolds number .
here @xmath6 denotes the fluid height whereas @xmath7 is the fluid velocity averaged with respect to height .
the terms @xmath8 and @xmath9 on the right hand side of the second equation model , respectively , gravitational force and turbulent friction along the bottom ..
Please generate the next two sentences of the article | roll - waves are well - known hydrodynamic instabilities of ( [ swe1 ] ) , arising in the region @xmath10 for which constant solutions , corresponding to parallel flow , are unstable .
they are commonly found in man - made conduits such as aqueducts and spillways , and have been reproduced in laboratory flumes @xcite . |
8,125 | Suppose that you have an abstract for a scientific paper: using hst nicmos 2 observations we have measured 1.6 @xmath0 m near infrared nuclear luminosities of 100 3cr radio galaxies with z @xmath1 0.3 , by modeling and subtracting the extended emission from the host galaxy .
we performed a multi - wavelength statistical analysis ( including optical and radio data ) of the properties of the nuclei following classification of the objects into fr i and fr ii , and lig ( low - ionization galaxies ) , hig ( high - ionization galaxies ) and blo ( broad - lined objects ) using the radio morphology and optical spectra , respectively .
the correlations among near infrared , optical , and radio nuclear luminosity support the idea that the near infrared nuclear emission of fr is has a non - thermal origin . despite the difference in radio morphology ,
the multi - wavelength properties of fr ii lig nuclei are statistically indistinguishable from those of fr is , an indication of a common structure of the central engine .
all blos show an unresolved near infrared nucleus and a large near infrared excess with respect to fr ii ligs and fr is of equal radio core luminosity .
this requires the presence of an additional ( and dominant ) component other than the non - thermal light .
considering the shape of their spectral energy distribution , we ascribe the origin of their near infrared light to hot circumnuclear dust .
a near infrared excess is also found in higs , but their nuclei are substantially fainter than those of blo .
this result indicates that substantial obscuration along the line - of - sight to the nuclei is still present at 1.6 @xmath0 m .
nonetheless , higs nuclei can not simply be explained in terms of dust obscuration : a significant contribution from light reflected in a circumnuclear scattering region is needed to account for their multiwavelength properties .
based on observations made with the nasa / esa hubble space telescope , obtained at the space telescope science institute , which is operated by the association of....
And you have already written the first three sentences of the full article: infrared observations of radio galaxies are a useful tool to explore the physics of their nuclei in the framework of the unified models for active galactic nuclei ( agn ) as in this band the impact of dust absorption is strongly reduced with respect to the optical . in particular , the study of the infrared nuclear sources allows us to investigate the ` scheme ' unifying different classes of agn , by exploring the properties of their accretion disks and the presence of any absorbing material that can account for the complex agn taxonomy . in the `` zeroth - order approximation '' of the agn unification scheme for radio - loud sources ( e.g. @xcite ) , powerful radio galaxies with fr ii edge - brightened morphology @xcite
are believed to be misaligned quasars , while lower power , edge - darkened fr is are associated with bl lac objects .
however , it is clear that this zeroth order approximation picture based on statistical comparison of the properties of radio - loud agn is over - simplified ..
Please generate the next two sentences of the article | inconsistencies between the characteristics of the `` parent '' and `` beamed ''
populations are well reported in the literature : for example , several bl lacs show broad emission lines ( e.g. @xcite ) ; and there are inconsistent environments ( e.g. @xcite ) and inconsistent radio morphologies ( e.g. @xcite ) ( see also @xcite and @xcite for reviews on this subject ) . |
8,126 | Suppose that you have an abstract for a scientific paper: approximate bayesian computation ( abc ) , also known as likelihood - free methods , have become a favourite tool for the analysis of complex stochastic models , primarily in population genetics but also in financial analyses .
we advocated in @xcite the use of abc for bayesian model choice in the specific case of gibbs random fields ( grf ) , relying on a sufficiency property mainly enjoyed by grfs to show that the approach was legitimate . despite having
previously suggested the use of abc for model choice in a wider range of models in the diy abc software @xcite , we present theoretical evidence that the general use of abc for model choice is fraught with danger in the sense that no amount of computation , however large , can guarantee a proper approximation of the posterior probabilities of the models under comparison . * keywords * : likelihood - free methods , bayes factor , diyabc , bayesian model choice , sufficiency . .
And you have already written the first three sentences of the full article: inference on population genetic models such as coalescent trees is one representative example of cases when statistical analyses like bayesian inference can not operate because the likelihood function associated with the data is not completely known , i.e. can not be computed in a manageable time @xcite .
the fundamental reason for this impossibility is that the statistical model associated with coalescent data needs to integrate over trees of extreme complexity . in such settings , traditional approximation tools based on monte carlo simulation @xcite from the bayesian posterior distribution
are unavailable for all practical purposes . indeed , due to the complexity of the latent structures defining the likelihood ( such as the coalescent tree ) , simulation of those structures is too unstable to be trusted to bring a reliable approximation in a manageable time ..
Please generate the next two sentences of the article | such complex models call for a practical if cruder approximation method , the abc methodology being a serious contender , where abc stands for _ approximate bayesian computation_. @xcite and @xcite introduced abc methods as a rejection technique bypassing the computation of the likelihood function via a simulation from the corresponding distribution . for recent reviews on abc , see @xcite and @xcite .
the wide and successful array of applications based on implementations of abc in genomics and ecology is covered by @xcite , while the number of publications relying on this technique runs in the hundreds . |
8,127 | Suppose that you have an abstract for a scientific paper: we propose quantum versions of the bell - ziv - zakai lower bounds on the error in multiparameter estimation . as an application we consider measurement of a time - varying optical phase signal with stationary gaussian prior statistics and a power law spectrum @xmath0 , with @xmath1 . with no other assumptions ,
we show that the mean - square error has a lower bound scaling as @xmath2 , where @xmath3 is the time - averaged mean photon flux .
moreover , we show that this accuracy is achievable by sampling and interpolation , for any @xmath1 .
this bound is thus a rigorous generalization of the heisenberg limit , for measurement of a single unknown optical phase , to a stochastically varying optical phase . .
And you have already written the first three sentences of the full article: the probabilistic nature of quantum mechanics imposes fundamental limits to hypothesis testing and parameter estimation @xcite .
such limits are relevant to many metrological applications , such as optical interferometry , optomechanical sensing , gravitational - wave detection @xcite , optical imaging @xcite , magnetometry , gyroscopy , and atomic clocks @xcite .
the ultimate quantum limits to parameter estimation have been studied extensively in recent years , as they imply that a minimum amount of resource , such as the average photon number for optical phase estimation , is needed to achieve a desired precision , regardless of the measurement method . for the measurement of a single optical phase parameter ,.
Please generate the next two sentences of the article | the ultimate quantum limit to the mean - square error scales as @xmath4 , where @xmath5 is the average photon number of the field which undergoes that phase shift .
this scaling is often called the heisenberg limit . |
8,128 | Suppose that you have an abstract for a scientific paper: when we model black hole accretion sources such as active galactic nuclei and black hole x - ray binaries as advection - dominated accretion flows ( adafs ) , it is neccesary to use the global solution to the equations rather than the simpler self - similar solution , since the latter is inaccurate in the region near the black hole where most of the radiation is emitted .
however , technically , it is a difficult task to calculate the global solution because of the transonic nature of the flow , which makes it a two - point boundary value problem . in this paper
we propose a simplified approach for calculating the global adaf solution .
we replace the radial momentum equation by a simple algebraic relation between the angular velocity of the gas and the keplerian angular velocity , while keeping all other equations unchanged .
it is then easy to solve the differential energy equations to obtain an approximate global solution . by adjusting the free parameters
, we find that for almost any accretion rate and for @xmath0 we can get good simplified global solutions .
the predicted spectra from the approximate solutions are very close to the spectra obtained from the true global solutions . .
And you have already written the first three sentences of the full article: advection - dominated accretion flow ( adaf ) is an important type of solution for black hole accretion .
a prominent feature of an adaf compared to the standard thin disk is its low radiative efficient at low accretion rates ( narayan & yi 1994 , hereafter ny94 ; narayan & yi 1995 ; see narayan , mahadevan & quataert 1998 and kato , fukue & mineshige 1998 for reviews ) .
the adaf solution has received much attention in the past years because it successfully explains why some nearby galaxies are so dim even though their accretion rates are not very small ( see narayan 2005 , yuan 2007 , and ho 2008 for reviews ) ..
Please generate the next two sentences of the article | the best evidence comes from the supermassive black hole in our galactic center , sgr a * ( narayan , mahadevan & yi 1995 ; manmoto , kusunoze & mineshige 1997 ; yuan , quataert & narayan 2003 ) . from _
observations and bondi theory , we can estimate the mass accretion rate of sgr a*. if the accretion flow were not an adaf but a standard thin disk , the luminosity would be five orders of magnitude larger than observed ( yuan , quataert & narayan 2003 ) . another attractive feature of an adaf is that it can partly solve the problem of the origin of x - ray emission from accretion flows . |
8,129 | Suppose that you have an abstract for a scientific paper: the effect of non periodic boundary conditions on decaying two - dimensional magnetohydrodynamic turbulence is investigated .
we consider a circular domain with no - slip boundary conditions for the velocity and where the normal component of the magnetic field vanishes at the wall .
different flow regimes are obtained by starting from random initial velocity and magnetic fields with varying integral quantities .
these regimes , equivalent to the ones observed by ting , matthaeus and montgomery [ phys .
fluids * 29 * , 3261 , ( 1986 ) ] in periodic domains , are found to subsist in confined domains .
we examine the effect of solid boundaries on the energy decay and alignment properties .
the final states are characterized by functional relationships between velocity and magnetic field . .
And you have already written the first three sentences of the full article: the influence of initial conditions on decaying magnetohydrodynamic ( mhd ) turbulence received considerable interest in the 1980 s , because of its relevance to explain solar - wind data @xcite .
indeed , in magnetohydrodynamics the behavior of decaying turbulent flow depends strongly on the initial conditions , and different initial values and ratios of integral quantities can lead to a wide variety of distinct behaviors .
the first systematic study of the different possible types of decay was performed by ting , matthaeus and montgomery @xcite , who identified four classes of possible decay behavior , corresponding roughly to a magnetically dominated , a hydrodynamically dominated , a magnetically - hydrodynamically equipartitioned and an erratic transition regime ..
Please generate the next two sentences of the article | their study considered the two - dimensional case , which is not only relevant in applications in which an externally imposed field renders the flows quasi two - dimensional , but also from a general physical understanding of mhd turbulence , which behaves quite similar in two and three dimensions , due to the equivalent role of the ideal invariants @xcite . whereas the influence of the initial conditions on decaying mhd turbulence has been studied and understood to some extend , studies on the effect of boundary conditions have been limited to low resolutions @xcite , imposed by the numerical methods used to account for boundaries .
even though these investigations highlighted interesting physics , higher resolution simulations are needed to obtain a better understanding of wall - bounded mhd , which plays a dominant role in geophysical flows in the core of planets such as the earth and industrial processes involving liquid metals . for the hydrodynamic case it was found that |
8,130 | Suppose that you have an abstract for a scientific paper: we study quasi - normal spectrum of the massive scalar field in the @xmath0-dimensional black hole background . we found the qualitatively different dependence of the fundamental modes on the field mass for @xmath1 .
the behaviour of higher modes is qualitatively the same for all @xmath0 .
thus for some particular values of @xmath2 , where @xmath3 is the field mass and @xmath4 is the black hole mass , the spectrum has two dominating oscillations with a very long lifetime .
we show that the asymptotically high overtones do not depend on the field mass .
in addition , we present the generalisation of the nollert improvement of the continued fraction technique for the numerical calculation of quasi - normal frequencies of @xmath0-dimensional black holes . .
And you have already written the first three sentences of the full article: one of the attractive solutions of the hierarchy problem is the consideration of our 4-dimensional universe as a sub - manifold that is embedded in a higher dimensional space - time .
the models of type add ( arkani - hamed , dimopoulos and dvali ) @xcite allow compactification radius of extra dimensions to be of macroscopic size @xcite .
black holes whose horizon radius is much smaller than this characteristic length can be well described by solution for higher - dimensional static black hole @xcite ..
Please generate the next two sentences of the article | such black holes could be produced at the next - generation particle colliders , probably at energies of very low order @xmath5 @xcite .
thus study of their properties is strongly motivated . |
8,131 | Suppose that you have an abstract for a scientific paper: we propose an empirical model to determine the form of energy loss of charm quarks due to multiple scatterings in quark gluon plasma by demanding a good description of production of d mesons and non - photonic electrons in relativistic collision of heavy nuclei at rhic and lhc energies .
best results are obtained when we approximate the momentum loss per collision @xmath0 , where @xmath1 is a constant depending on the centrality and the centre of mass energy .
comparing our results with those obtained earlier for drag coefficients estimated using langevin equation for heavy quarks we find that up to half of the energy loss of charm quarks at top rhic energy could be due to collisions while that at lhc energy at 2760 gev / a the collisional energy loss could be about one third of the total .
estimates are obtained for azimuthal anisotropy in momentum spectra of heavy mesons , due to this energy loss .
we further suggest that energy loss of charm quarks may lead to an enhanced production of d - mesons and single electrons at low @xmath2 in aa collisions .
key - words : charm quark , d - mesons , non - photonic electrons , qgp , nuclear modification , azimuthal anisotropy , relativistic heavy ion collisions pacs indices : 14.65.dw , 14.40.lb , 13.30.ce , 12.38.mh , 25.75.dw .
And you have already written the first three sentences of the full article: the vast amount of data collected at the relativistic heavy ion collider at brookhaven national laboratory along with those recently collected from the collision of lead nuclei at large hadron collider at cern have led to the momentous discovery of quark gluon plasma ( qgp ) .
a large part of the effort in the coming years will be devoted to the determination of the precise values of the transport properties of the qgp . in this context , the energy loss suffered by quarks of different flavours and gluons as they traverse the qgp , undergoing collisions and radiating gluons , is a subject matter of considerable topical interest .
it is most simply demonstrated by a suppressed production of hadrons having large transverse momenta in nucleus - nucleus collisions when compared to appropriately scaled productions in @xmath3 collisions at the same centre of mass energy per nucleon ..
Please generate the next two sentences of the article | it is often suggested that heavy quarks may lose a smaller amount of energy per unit length during their passage through qgp compared to light quarks , due to the dead cone effect @xcite .
the experimental results , however , show similar suppression for light and heavy mesons @xcite . a recent calculation by abir et al @xcite incorporating |
8,132 | Suppose that you have an abstract for a scientific paper: we investigate maxwell s attempt to justify the mathematical assumptions behind his 1860 proposition iv according to which the velocity components of colliding particles follow the normal distribution .
contrary to the commonly held view we find that his molecular collision model plays a crucial role in reaching this conclusion , and that his model assumptions also permit inference to equalization of mean kinetic energies ( temperatures ) , which is what he intended to prove in his discredited and widely ignored proposition vi .
if we take a charitable reading of his own proof of proposition vi then it was maxwell , and not boltzmann , who gave the first proof of a tendency towards equilibrium , a sort of h - theorem .
we also call attention to a potential conflation of notions of probabilistic and value independence in relevant prior works of his contemporaries and of his own , and argue that this conflation might have impacted his adoption of the suspect independence assumption of proposition iv . maxwell , kinetic theory , statistical mechanics , normal distribution , independence , h - theorem , second law of thermodynamics , condition a .
And you have already written the first three sentences of the full article: james clerk maxwell s early work on the kinetic theory of gases was a major step - stone in the introduction of probabilistic methods into physics .
proposition iv of maxwell s @xcite _ illustrations of the dynamical theory of gases _ , his first derivation of the velocity distribution law , is frequently cited as `` one of the most important passages in physics '' @xcite and as such had been thoroughly investigated in the works of s. g. brush @xcite , m. c. dias @xcite , c. w. f. everitt @xcite , e. garber @xcite , c. c. gillispie @xcite , p. m. heimann @xcite , t. m. porter @xcite , c. truesdell @xcite , j. uffink @xcite and other historians of science .
proposition iv shows that , given certain assumptions , the three velocity components of molecules of a box of gas follow the normal distribution and the speed ( the magnitude of velocity ) follows what nowadays is called the maxwell - boltzmann distribution ..
Please generate the next two sentences of the article | this paper provides a new conceptual and historical analysis of maxwell s derivation .
we make four contributions to the literature . |
8,133 | Suppose that you have an abstract for a scientific paper: clusters are the dense inner regions of a wide - spread hierarchy of young stellar structures .
they often reveal a continuation of this hierarchy inside of them , to smaller scales , when they are young , but orbital mixing eventually erases these subparts and a only smooth cluster or smooth unbound group remains .
the stellar hierarchy follows a similar structure in the interstellar gas , which is presumably scale - free because of supersonic motions in the presence of turbulence and self - gravity .
the efficiency of star formation increases automatically with density in a hierarchical ism , causing most dense stellar groups to be initially bound for local conditions . in lower pressure environments ,
the infant mortality rates should be higher . also following from hierarchical structure
is the cluster mass distribution function and perhaps also the cluster size distribution function , although the predicted mass - size relation is not observed .
cluster destruction is from a variety of causes .
the destruction time should depend on cluster mass , but the various groups who have studied this dependence have gotten significantly different results so far . .
And you have already written the first three sentences of the full article: we know what a cluster is when we see one , but there is a lot more to clustering than meets the eye . embedded clusters often contain sub - clusters , for example , and clusters generally cluster together themselves into double clusters or star complexes . taken together , there is a hierarchy of young stellar structures , with the objects commonly called clusters representing only the inner and denser parts of the hierarchy .
presumably the main difference between the clusters and the rest of the hierarchy is that the clusters have had sufficient time and gravitational self - attraction to get mixed by stellar orbital motions .
the rest of the hierarchy could partially mix later , by cluster coalescence , for example , or it could disburse through tidal forces . the subclustering of clusters is evident when the clusters are still young in terms of their dynamical time ..
Please generate the next two sentences of the article | examples are ngc 2264 , which has four subclusters with slightly different ages ( @xmath0 my ; dahm & simon 2005 ) , rho oph ( smith et al . 2005 ) , and serpens ( testi et al . 2000 ) .
not all clusters will be born with clear sub - clustering . |
8,134 | Suppose that you have an abstract for a scientific paper: we present a comprehensive study of stellar stratification in young star clusters in the large magellanic cloud ( lmc ) .
we apply our recently developed _ effective radius method _ for the assessment of stellar stratification on imaging data obtained with the advanced camera for surveys of three young lmc clusters to characterize the phenomenon and develop a comparative scheme for its assessment in such clusters .
the clusters of our sample , ngc 1983 , ngc 2002 and ngc 2010 , are selected on the basis of their youthfulness , and their variety in appearance , structure , stellar content , and surrounding stellar ambient .
our photometry is complete for magnitudes down to @xmath0 mag , allowing the calculation of the structural parameters of the clusters , the estimation of their ages and the determination of their stellar content .
our study shows that each cluster in our sample demonstrates stellar stratification in a quite different manner and at different degree from the others .
specifically , ngc 1983 shows to be _ partially _ segregated with the effective radius increasing with fainter magnitudes only for the faintest stars of the cluster .
our method on ngc 2002 provides evidence of _ strong _ stellar stratification for both bright and faint stars ; the cluster demonstrates the phenomenon with the highest degree in the sample .
finally , ngc 2010 is _ not segregated _ , as its bright stellar content is not centrally concentrated , the relation of effective radius to magnitude for stars of intermediate brightness is rather flat , and we find no evidence of stratification for its faintest stars . for the parameterization of the phenomenon of stellar stratification and its quantitative comparison among these clusters ,
we propose the slope derived from the change in the effective radius over the corresponding magnitude range as indicative parameter of the _ degree of stratification _ in the clusters . a positive value of this slope indicates mass segregation in the cluster , while....
And you have already written the first three sentences of the full article: _ stellar stratification _ is a characteristic phenomenon of star clusters , which has been well documented for more than 50 years .
it is directly linked to the dynamical evolution of star clusters @xcite , and specifically to the central concentration of the massive stars as the cluster relaxes dynamically , a phenomenon known as _ mass segregation _ ( for detailed reviews see * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | this behavior in massive galactic globular clusters ( ggcs ) is well understood and the observed mass segregation is explained as a result of their dynamical relaxation in a timescale , @xmath1 , much longer than their ages , @xmath2 , as derived from stellar evolutionary models . this _ dynamical _ mass segregation , thus , forces more massive stars to sink inwards to the center of a cluster through weak two - body interactions .
however , segregation of massive stars is observed also in young star clusters , such as the @xmath3 30 myr - old cluster ngc 330 in the small magellanic cloud @xcite , or even the @xmath3 1 myr - old galactic starburst ngc 3603 @xcite . |
8,135 | Suppose that you have an abstract for a scientific paper: jet cross sections in deep - inelastic scattering over a wide region of phase space have been measured at hera .
these cross section measurements provide a thorough test of the implementation of quantum chromodynamics in next - to - leading order ( nlo ) calculations .
they also provide the opportunity to test the consistency of the gluon distribution in the proton as extracted from ( mainly ) inclusive dis measurements .
comparison of the cross sections with nlo enables accurate extractions of the strong coupling constant , @xmath0 , to be made , several of which are reported here . .
And you have already written the first three sentences of the full article: deep - inelastic @xmath1 scattering ( dis ) at hera , in which a photon of virtuality , @xmath2 , is exchanged , can lead to the production of jets in the final state .
cross - section measurements of these types of processes provide stringent tests of the perturbative quantum chromodynamics ( pqcd ) formalism in next - to - leading order ( nlo ) calculations , the structure of the proton and allow measurements of the strong coupling constant , @xmath0 .
these features can be seen in the formula for the cross section , @xmath3 , which is factorised into a convolution of the hard partonic cross section , @xmath4 , and the proton s parton density , @xmath5 : @xmath6 the hard partonic cross section is a power series expansion in @xmath0 and is calculable in pqcd ..
Please generate the next two sentences of the article | the proton s parton density is derived from fits to published data , such as inclusive dis measurements @xcite and high transverse energy jet production in @xmath7 production @xcite . in the region of momentum fraction , @xmath8 , and @xmath2 in which dis jet measurements are currently performed ,
the quark density in the photon is well constrained from particularly inclusive dis measurements . at high @xmath2 where the quark initiated process , qcd compton ( see figure [ fig : feyn](a ) ) , is dominant |
8,136 | Suppose that you have an abstract for a scientific paper: the intrinsic volumes of gaussian polytopes are considered . a lower variance bound for these quantities
is proved , showing that , under suitable normalization , the variances converge to strictly positive limits .
the implications of this missing piece of the jigsaw in the theory of gaussian polytopes are discussed . + * keywords*. gaussian polytopes , random polytopes , stochastic geometry , variance lower bound + * msc*. primary 60d05 ; secondary 52a22 . .
And you have already written the first three sentences of the full article: fix a space dimension @xmath0 and denote by @xmath1 the standard gaussian measure on @xmath2 with density @xmath3 equal to @xmath4 given @xmath5 let @xmath6 be independent random points that are distributed on @xmath7 according to the probability measure @xmath1 . the random convex hull @xmath8\ ] ] of these points is a _
gaussian polytope_. random polytopes of this type are central objects considered in stochastic geometry and are also of importance in convex geometric analysis or coding theory .
for example , gluskin @xcite has used gaussian polytopes in his analysis of the diameter of the minkowski compactum and gaussian polytopes also arise as lower - dimensional shadows of randomly rotated high - dimensional regular simplices as shown by baryshnikov and vitale @xcite ..
Please generate the next two sentences of the article | we refer to the survey article of reitzner @xcite for further background information and references .
we denote for @xmath9 by @xmath10 the @xmath11th intrinsic volume of @xmath12 , that is , @xmath13 here , @xmath14 is the grassmannian of @xmath11-dimensional linear subspaces of @xmath7 supplied with the unique haar probability measure @xmath15 and @xmath16 stands for the @xmath11-dimensional lebesgue measure of the orthogonal projection @xmath17 of @xmath12 onto @xmath18 . |
8,137 | Suppose that you have an abstract for a scientific paper: we present a new framework for solving optimization problems with a diseconomy of scale . in such problems ,
our goal is to minimize the cost of resources used to perform a certain task .
the cost of resources grows superlinearly , as @xmath0 , @xmath1 , with the amount @xmath2 of resources used .
we define a novel linear programming relaxation for such problems , and then show that the integrality gap of the relaxation is @xmath3 , where @xmath3 is the @xmath4-th moment of the poisson random variable with parameter 1 . using our framework , we obtain approximation algorithms for the minimum energy efficient routing , minimum degree balanced spanning tree , load balancing on unrelated parallel machines , and unrelated parallel machine scheduling with nonlinear functions of completion times problems .
our analysis relies on the decoupling inequality for nonnegative random variables .
the inequality states that @xmath5 where @xmath6 are independent nonnegative random variables , @xmath7 are possibly dependent nonnegative random variable , and each @xmath7 has the same distribution as @xmath6 .
the inequality was proved by de la pea in 1990 .
de la pea , ibragimov , and sharakhmetov showed that @xmath8 for @xmath9 and @xmath10 for @xmath11 .
we show that the optimal constant is @xmath12 for any @xmath13 .
we then prove a more general inequality : for every convex function @xmath14 , @xmath15 } \leq { { \mathbb{e}}\left[\varphi\big(p\sum_{i=1}^n y_i\big)\right]},\ ] ] and , for every _ concave _ function @xmath16 , @xmath17 } \geq { { \mathbb{e}}\left[\psi\big(p\sum_{i=1}^n y_i\big)\right]},\ ] ] where @xmath18 is a poisson random variable with parameter 1 independent of the random variables @xmath7 . .
And you have already written the first three sentences of the full article: in this paper , we study combinatorial optimization problems with a diseconomy of scale .
we consider problems in which we need to minimize the cost of resources used to accomplish a certain task .
often , the cost grows linearly with the amount of resources used . in some applications , the cost is sublinear e.g. , if we can get a discount when we buy resources in bulk ..
Please generate the next two sentences of the article | such phenomenon is known as economy of scale " . however , in many applications the cost is superlinear . in such cases , we say that the cost function exhibits a `` diseconomy of scale '' .
a good example of a diseconomy of scale is the cost of energy used for computing . |
8,138 | Suppose that you have an abstract for a scientific paper: cayley s ( ruled cubic ) surface carries a three - parameter family of twisted cubics .
we describe the contact of higher order and the dual contact of higher order for these curves and show that there are three exceptional cases . _
2000 mathematics subject classification : _
53a20 , 53a25 , 53a40 . _
keywords : _ cayley surface , twisted cubic , contact of higher order , dual contact of higher order , twofold isotropic space .
_ dedicated to gunter wei on the occasion of his 60th birthday , in friendship _ .
And you have already written the first three sentences of the full article: * .. * the geometry on cayley s surface and the geometry in the ambient space of cayley s surface has been investigated by many authors from various points of view .
see , among others , @xcite , @xcite , @xcite , @xcite , and @xcite . in these papers
the reader will also find a lot of further references . as a by - product of a recent publication @xcite , it turned out that the cayley surface ( in the real projective @xmath0-space ) carries a one - parameter family of twisted cubics which have mutually contact of order four ..
Please generate the next two sentences of the article | these curves belong to a well - known three - parameter family of twisted cubics @xmath1 on cayley s surface ; cf .
formula ( [ eq : abc_proj ] ) below . |
8,139 | Suppose that you have an abstract for a scientific paper: * abstract * in this paper , we reconstruct cosmological models in the framework of @xmath0 gravity , where @xmath1 is the ricci scalar and @xmath2 is the trace of the stress - energy tensor .
we show that the dust fluid reproduces @xmath3cdm , phantom - non - phantom era and the phantom cosmology .
further , we reconstruct different cosmological models including , chaplygin gas , scalar field with some specific forms of @xmath0 .
our numerical simulation for hubble parameter shows good agreement with the bao observational data for low redshifts @xmath4 . .
And you have already written the first three sentences of the full article: from the cosmological observational data @xcite , it is now well established that the present observable universe is undergoing an accelerating expansion . while the source driving this cosmic acceleration
is known as ` dark energy ' its origin has not been well understood yet due to absence of a consistent theory of quantum gravity .
this acceleration is driven by the negative pressure of the dark energy ..
Please generate the next two sentences of the article | the ` cosmological constant ' is the most simple and natural candidate for explaining cosmic acceleration but it faces serious problems of fine - tuning and large mismatch between theory and observations @xcite . hence there has been significant development in the construction of dark energy models by modifying the geometrical part of the einstein - hilbert action .
this phenomenological approach is called as the modified gravity which can successfully explain the rotation curves of galaxies , the motion of galaxy clusters , the bullet cluster , and cosmological observations without the use of dark matter or einstein s cosmological constant @xcite . |
8,140 | Suppose that you have an abstract for a scientific paper: the arrival directions of multi - tev cosmic rays show significant anisotropies at small angular scales . it has been argued that this small - scale structure can naturally arise from cosmic ray scattering in _ local _ turbulent magnetic fields that distort a global dipole anisotropy set by diffusion .
we study this effect in terms of the power spectrum of cosmic ray arrival directions and show that the strength of small - scale anisotropies is related to properties of relative diffusion .
we provide a formalism for how these power spectra can be inferred from simulations and motivate a simple analytic extension of the ensemble - averaged diffusion equation that can account for the effect . .
And you have already written the first three sentences of the full article: the propagation of cosmic rays ( crs ) through turbulent magnetic fields is effectively described as a diffusion process .
this approach provides an excellent description of the observed spectra and chemical abundances of galactic crs up the cr knee at a few pev .
the arrival direction of crs is mostly isotropized in this process and the location of the sources is hidden ..
Please generate the next two sentences of the article | the first order correction to the isotropic distribution is a small dipole anisotropy that scales with the local cr gradient according to fick s law .
the phase and strength of this dipole is expected to be a combined effect of the relative motion of the solar system with respect to the frame where crs are isotropic @xcite , the density gradient of crs , the strength of diffusion , and the strength and orientation of regular magnetic fields @xcite . |
8,141 | Suppose that you have an abstract for a scientific paper: the electron - phonon coupling in self - assembled ingaas quantum dots is relatively weak at low light intensities , which means that the zero - phonon line in emission is strong compared to the phonon sideband .
however , the coupling to acoustic phonons can be dynamically enhanced in the presence of an intense optical pulse tuned within the phonon sideband .
recent experiments have shown that this dynamic vibronic coupling can enable population inversion to be achieved when pumping with a blue - shifted laser and for rapid de - excitation of an inverted state with red detuning . in this paper
we confirm the incoherent nature of the phonon - assisted pumping process and explore the temperature dependence of the mechanism .
we also show that a combination of blue- and red - shifted pulses can create and destroy an exciton within a timescale @xmath0ps determined by the pulse duration and ultimately limited by the phonon thermalisation time . .
And you have already written the first three sentences of the full article: vibronic sidebands are observed in the optical spectra of many solid - state materials @xcite , with ti : sapphire @xcite and nitrogen - vacancy ( nv ) centres in diamond @xcite being good examples .
the key point about a vibronic transition is that it involves the simultaneous absorption or emission of a photon and a phonon ( or phonons ) as the electron jumps between two electronic states .
the sideband spectra are continuous bands , although sub - structure can frequently be identified due to the involvement of specific phonon modes , especially at low temperatures ..
Please generate the next two sentences of the article | for example , in the case of nv centres in diamond , clear structure can be identified that corresponds to the coupling of the electronic state to the a@xmath1 mode ( @xmath2 mev ) , giving rise to resolved side - peaks in both absorption and emission at integer multiples of the phonon energy @xcite .
the coupling to the vibrational modes is so strong that only a few percent of the emission occurs in the zero - phonon line , with most of the photons emitted from the sidebands @xcite . |
8,142 | Suppose that you have an abstract for a scientific paper: a clifford algebra @xmath0 jointly with a clifford cogebra @xmath1 is said to be a clifford biconvolution @xmath2 we show that a clifford biconvolution for @xmath3 does possess an antipode iff @xmath4 an antipodal clifford biconvolution is said to be a clifford hopf gebra . + * 2000 mathematics subject classification : * 15a66 clifford algebra , 16w30 coalgebra , bialgebra , hopf algebra + * 2000 pacs : * 02.10.tq associative rings and algebras + * keywords : * cliffordization , clifford algebra , clifford cogebra , antipode , hopf gebra , clifford bigebra , gramann algebra .
And you have already written the first three sentences of the full article: after bourbaki [ 1989 11 ] we use _ cogebra , bigebra _ and hopf _ gebra _ instead of coalgebra , bialgebra and hopf algebra .
let @xmath5 be an @xmath6-space and @xmath7 be an @xmath6-dual @xmath6-space .
if @xmath5 is an @xmath6-cogebra and @xmath8 is an @xmath6-algebra then the @xmath6-space @xmath9 inherits the structure of an @xmath6-algebra with a convolution product : this is a convolution @xmath6-algebra , an @xmath6-convolution for short ..
Please generate the next two sentences of the article | a dual @xmath6-space @xmath10 inherits a structure of an @xmath6-cogebra with coconvolution coproduct : this is a coconvolutional @xmath6-cogebra , an @xmath6-coconvolution for short .
in particular if an @xmath6-space @xmath11 carries an @xmath6-biconvolution algebra & cogebra structure , then do also the @xmath6-spaces @xmath12 as well as all iterated @xmath6-spaces @xmath13 inherit also @xmath6-biconvolution algebra & cogebra structures . |
8,143 | Suppose that you have an abstract for a scientific paper: the orientational order in vertically agitated granular rod monolayers is investigated experimentally and compared quantitatively with equilibrium monte carlo simulations and density functional theory . at sufficiently high number density ,
short rods form a tetratic state and long rods form a uniaxial nematic state
. the length - to - width ratio at which the order changes from tetratic to uniaxial is around @xmath0 in both experiments and simulations .
this agreement illustrates the universal aspects of the ordering of rod - shaped particles across equilibrium and nonequilibrium systems .
moreover , the assembly of granular rods into ordered states is found to be independent of the agitation frequency and strength , suggesting that the detailed nature of energy injection into such a nonequilibrium system does not play a crucial role . .
And you have already written the first three sentences of the full article: the ordering of anisotropic particles is a universal phenomenon appearing widely in nature , ranging from thermally driven molecules or colloids @xcite to active particles such as bacteria colonies @xcite , actin filaments @xcite , animal groups @xcite , and living liquid crystals @xcite . in equilibrium lyotropic systems , such as hard rods interacting only through excluded volume interactions ,
the transition of sufficiently anisotropic particles into various ordered states is entropy driven .
the loss in rotational degrees of freedom in the ordered state is compensated by the gain in the translational ones @xcite ..
Please generate the next two sentences of the article | taking a two - dimensional system of hard rectangles as an example , a tetratic state with four - fold rotational symmetry was discovered in monte carlo ( mc ) simulations @xcite , and studied theoretically with density functional theory ( dft ) @xcite .
the number density and the length - to - width ratio ( aspect ratio ) of the particles were found to be the key parameters determining the ordered states of hard rectangles with only excluded volume interactions @xcite . given the ubiquity of ordering transitions in nature , it is important to ask how well the existing knowledge about such transitions in equilibrium ( thermal ) systems can be extended to nonequilibrium ( athermal ) systems . due to the dissipative interactions between particles , |
8,144 | Suppose that you have an abstract for a scientific paper: the veritas imaging atmospheric cherenkov telescope array has been observing the northern tev sky with four telescopes since summer 2007 .
over 50 gamma - ray sources have been studied , including active and starburst galaxies , pulsars and their nebulae , supernova remnants and galactic binary systems .
we review here some of the most recent veritas results , and discuss the status and prospects for collaborative work with other gamma - ray instruments , and with multimessenger observatories . .
And you have already written the first three sentences of the full article: veritas ( figure [ veritas ] ) is an imaging atmospheric cherenkov telescope array , now entering its tenth year of operations .
the array consists of four identical telescopes , located at the fred lawrence whipple observatory ( flwo ) in arizona , each with a @xmath0 diameter tessellated reflector .
cherenkov light from gamma - ray and cosmic - ray initiated particle cascades is focused by the telescope reflectors onto 499-pixel photomultiplier tube ( pmt ) cameras , which cover a @xmath1 field of view ..
Please generate the next two sentences of the article | the array has undergone two major upgrades over the past decade .
the first , in 2009 , involved the relocation of the original prototype telescope to a more favorable location , resulting in an approximate diamond - shaped layout with sides of @xmath2 . |
8,145 | Suppose that you have an abstract for a scientific paper: under the assumption that ls 5039 is a system composed by a pulsar rotating around an o6.5v star in a @xmath0 day orbit , we present the results of a theoretical modeling of the high energy phenomenology observed by the high energy stereoscopy array ( h.e.s.s . ) .
this model ( including detailed account of the system geometry , klein - nishina inverse compton , @xmath1-@xmath1 absorption , and cascading ) is able to describe well the rich observed phenomenology found in the system at all timescales , both flux and spectrum - wise . .
And you have already written the first three sentences of the full article: a few binaries have been identified as variable very - high - energy ( vhe ) @xmath1-ray sources ( aharonian et al .
2005a , b ; 2006 , albert et .
al . 2006 , 2007 ) . for ls 5039 ,.
Please generate the next two sentences of the article | a periodicity in the @xmath1-ray flux , consistent with the orbital timescale as determined by casares et al .
( 2005 ) , was found with amazing precision ( aharonian et al . |
8,146 | Suppose that you have an abstract for a scientific paper: we consider a hyperbolic system of conservation laws @xmath0 where each characteristic field is either linearly degenerate or genuinely nonlinear . under the assumption of coinciding shock and rarefaction curves and the existence of a set of riemann coordinates @xmath1 , we prove that there exists a semigroup of solutions @xmath2 , defined on initial data @xmath3 .
the semigroup @xmath4 is continuous w.r.t .
time and the initial data @xmath5 in the @xmath6 topology .
moreover @xmath4 is unique and its trajectories are obtained as limits of wave front tracking approximations .
s.i.s.s.a . ref . 65/2000/m .
And you have already written the first three sentences of the full article: consider the cauchy problem for a strictly hyperbolic system of conservation laws @xmath7 where @xmath8 and @xmath9 is sufficiently smooth , @xmath10 open . if the initial data @xmath5 is of small total variation , the global existence was proved first in @xcite .
moreover a series of paper @xcite establishes the uniqueness and well posedness of the cauchy problem .
however , when @xmath5 has large total variation or even more generally @xmath5 belongs to @xmath11 , the solution @xmath12 may not exist globally in @xmath11 @xcite : only for special system it is possible to consider initial data with large total variation ..
Please generate the next two sentences of the article | we recall some of the results available in this direction . * for scalar conservation laws , the entropic solution to generates a contractive semigroup w.r.t the @xmath13 distance , on a domain of @xmath11 data @xcite .
* for general temple class system , in @xcite it is proved the existence and stability of the entropic solution for initial data with arbitrarily large but bounded total variation . * |
8,147 | Suppose that you have an abstract for a scientific paper: the performance expected from a galaxy survey to be carried out with gaia , the gaia galaxy survey , is outlined . from a statistical model of galaxy number density , size and surface brightness distribution , and from detailed numerical simulations based on real images
, it is conservatively estimated that gaia would be able to detect and observe about 3 million galaxies brighter than @xmath0 and to provide multi - colour and multi - epoch broad - band photometry of these with an end - of - mission angular resolution of @xmath1 0.35 and a photometric accuracy of @xmath2 0.2 at @xmath3 . the substantial scientific case for performing such a survey and the additional efforts required in terms of mission preparation ,
operations and telemetry are also discussed . .
And you have already written the first three sentences of the full article: since the very beginning of the feasibility studies , the gaia mission design was driven by the need of determining the position and the brightness of huge numbers of stars with the uttermost accuracy . during the concept and technologt study completed in july 2000 ( see @xcite and @xcite ) , however , it clearly emerged that such a star - driven mission could also provide , several socalled by - products which would substantially enrich its already impressive scientific yield .
in particular , it was realized that the scientific case for gaia imaging of high - surface brightness sky regions such as the central regions of nearby galaxies was dramatic .
the issues connected with this opportunity have been addressed in a certain detail in a number of studies ( see @xcite , @xcite , @xcite and @xcite ) , and such observations were included in the mission baseline design as described in @xcite under the name of gaia galaxy survey . in this paper.
Please generate the next two sentences of the article | the current ideas on the implementation of such a survey and on the expected performance are presented . in section 2 the overall strategy for galaxy detection and observation with gaia
is outlined . in sections 3 and 4 the detection and observation , |
8,148 | Suppose that you have an abstract for a scientific paper: the problem of three - dimensional ( 3-d ) wind profile prediction is addressed based a trinion wind model , which inherently reckons the coupling of the three perpendicular components of a wind field . the augmented trinion statistics are developed and employed to enhance the prediction performance due to its full exploitation of the second - order statistics .
the proposed trinion domain processing can be regarded as a more compact version of the existing quaternion - valued approach , with a lower computational complexity .
simulations based on recorded wind data are provided to demonstrate the effectiveness of the proposed methods .
wind profile prediction , trinion - valued representation , least mean squares , adaptive filtering , widely linear processing .
And you have already written the first three sentences of the full article: hypercomlex numbers are high - dimensional extensions of real numbers @xcite , and they have been introduced to solve multivariate signal processing problems , such as colour image processing @xcite , vector - sensor array signal processing @xcite , human gesture spotting @xcite , wind profile prediction @xcite , and wireless communications @xcite . in the last application ,
anemometer readings are modeled with hypercomplex numbers and the wind profile is predicted by adaptive filtering algorithms . in particular , pure quaternions have been widely used to model three - dimensional ( 3d ) wind speed .
when external atmospheric parameters are available , a full quaternion - valued model can be considered @xcite ..
Please generate the next two sentences of the article | the quaternion - valued model leads to improved performance over real - valued models , since it accounts for the coupling of the wind measurements and can be extended to exploiting the augmented quaternion statistics @xcite . however
, pure quaternions do not form a mathematical ring @xcite , since the product of two pure quaternions is not a pure quaternion in general . as a result |
8,149 | Suppose that you have an abstract for a scientific paper: quantum properties are soon subject to decoherence once the quantum system interacts with the classical environment . in this paper
we experimentally test how propagation losses , in a gaussian channel , affect the bi
partite gaussian entangled state generated by a sub threshold type ii opticla parametric oscillator ( opo ) .
experimental results are discussed in terms of different quantum markers , as teleportation fidelity , quantum discord and mutual information , and continuous variable ( cv ) entanglement criteria .
to analyse state properties we have retrieved the composite system covariance matrix by a single homodyne detector .
we experimentally found that , even in presence of a strong decoherence , the generated state never disentangles and keeps breaking the quantum limit for the discord .
this result proves that the class of cv entangled states discussed in this paper would allow , in principle , to realize quantum teleportation over an infinitely long gaussian channel . .
And you have already written the first three sentences of the full article: quantumness is very fragile and its surviving over long distances and times is subtly interconnected to the amount of noise coupling into the quantum system through its unavoidable interaction with the classical environment . among the different quantum signatures , entanglement
, a concept firstly introduced by schrdinger @xcite in response to the famous einstein , podolsky and rosen paper in 1935 @xcite , probably represents the most fascinating one .
the conceptual consequences of entanglement are somehow subtle and deeply affect many aspects of modern physics as the interaction between reality and observer @xcite , the actual limit for defining metrology standards @xcite , the limit to communication security @xcite ..
Please generate the next two sentences of the article | the optical realization of such an intriguing quantum feature has gained , in the last decades , a central role for realising complex quantum communication protocols @xcite . among the different approaches the use of bright beams , _
i.e. _ optical modes carrying many photons , appears as the most robust carrier of entangled information @xcite no matter if the latter will be coded into single photon like states ( discrete quantum coding ) or over the quadratures of the carrier beams ( continuous valued quantum coding ) @xcite . by interacting with the external world , a pure quantum state decoheres into a mixture @xcite and its quantumness , if not completely death @xcite , need to be restored or re enhanced by suitable protocols shor95 . as a matter of fact , |
8,150 | Suppose that you have an abstract for a scientific paper: there is currently no explanation of why the corona has the temperature and density it has .
we present a model which explains how the dynamics of magnetic reconnection regulates the conditions in the corona .
a bifurcation in magnetic reconnection at a critical state enforces an upper bound on the coronal temperature for a given density .
we present observational evidence from 107 flares in 37 sun - like stars that stellar coronae are near this critical state
. the model may be important to self - organized criticality models of the solar corona . .
And you have already written the first three sentences of the full article: dynamics in the solar corona takes on a wide range of forms . on one hand ,
the corona is the setting for the most violent eruptions in the solar system : solar flares and coronal mass ejections @xcite . on the other , coronal
heating makes the corona almost a thousand times hotter than the photosphere , even in the quiet sun @xcite ..
Please generate the next two sentences of the article | @xcite unified these two phenomena by proposing that micro- and nano - flares , less energetic cousins of eruptive flares , heat the corona .
this model gained credence from studies showing that solar flares exhibit power law statistics @xcite over a wide range of scales for many quantities . |
8,151 | Suppose that you have an abstract for a scientific paper: based on keldysh s nonequilibrium green function method , the spin - dependent transport properties in a ferromagnet - quantum dot ( qd)-ferromagnet coupled system are investigated .
it is shown the spin current shows quite different characteristics from its electrical counterpart , and by changing the relative orientation of both magnetizations , it can change its magnitude even sign .
the current - induced spin transfer torque ( cistt ) is uncovered to be greatly enhanced when the bias voltage meets with the discrete levels of the qd at resonant positions .
the relationship between the cistt , the electrical current and the spin current is also addressed . .
And you have already written the first three sentences of the full article: investigations on the spin - dependent transport in a magnetic tunnel junction ( mtj ) have attracted much interest in the last decade , as the mtjs have essential applications in spintronic devicesprinz , wolf , zutic , maekawa , su .
one of phenomena in mtjs is the so - called tunnel magnetoresistance ( tmr ) effect , which states that the tunneling current through the junction depends sensitively on the relative orientation of the magnetizations of both ferromagnetic electrodes , that is caused by the spin - dependent scattering of conduction electrons .
the difference between the currents through spin up and down channels in mtjs is usually referred to as the spin current@xcite . on the other hand , a reverse effect to tmr.
Please generate the next two sentences of the article | was predicted independently by slonczewski@xcite and berger@xcite , i.e. , the spin - polarized electrons passing from the left ferromagnetic layer into the right layer in which the magnetization deviates the left by an angle may exert a torque to the right ferromagnet and can change the orientation of its magnetization .
this effect was coined as the spin transfer effect ( for review , see e.g. ref.@xcite ) , which can lead to the current - induced magnetization reversal , and might offer a promise for the current - controlled spintronic devices . |
8,152 | Suppose that you have an abstract for a scientific paper: we study the lyapunov spectrum of the kontsevich zorich cocycle on @xmath0-invariant subbundles of the hodge bundle over the support of @xmath0-invariant probability measures on the moduli space of abelian differentials .
in particular , we prove formulas for partial sums of lyapunov exponents in terms of the second fundamental form ( the kodaira spencer map ) of the hodge bundle with respect to gauss
manin connection and investigate the relations between the central subbundle and the kernel of the second fundamental form .
we illustrate our conclusions in two special cases . .
And you have already written the first three sentences of the full article: consider a billiard on the plane with @xmath1-periodic rectangular obstacles as in figure [ fig : windtree ] . in @xcite , it is shown that for almost all parameters @xmath2 of the obstacle ( i.e. , lenghts @xmath3 of the sides of the rectangular obstacles ) , for almost all initial directions @xmath4 , and for any starting point @xmath5 the billiard trajectory @xmath6 escapes to infinity with a rate @xmath7 ( unless it hits the corner ) : @xmath8 note that changing the height and the width of the obstacle ( see figure [ fig : different : billiards ] ) we get quite different billiards , but this does not change the diffusion rate .
the number `` @xmath9 '' here is the lyapunov exponent of a certain renormalizing dynamical system associated to the initial one .
more precisely , it is the lyapunov exponent of certain subbundle of the hodge bundle under the kontsevich zorich cocycle ..
Please generate the next two sentences of the article | the lyapunov exponents of the hodge bundle also govern the deviation spectrum for the asymptotic cycle of an orientable measured foliation , as well as the rate of convergence of ergodic averages for interval exchange transformations and for certain area preserving flows on surfaces see @xcite , @xcite , @xcite .
the range of phenomena where the lyapunov exponents of the hodge bundle are extremely helpful keeps growing : nowadays , it includes , in particular , the evaluation of volumes of the moduli spaces of quadratic differentials on @xmath10 , see @xcite , and the classification of commensurability classes of all presently known non - arithmetic ball quotients @xcite . in this paper |
8,153 | Suppose that you have an abstract for a scientific paper: remote observation of spectroscopic emissions is a potential tool for the identification and quantification of various species in comets .
co cameron band ( to trace co@xmath0 ) and atomic oxygen emissions ( to trace h@xmath0o and/or co@xmath0 , co ) have been used to probe neutral composition in the cometary coma . using a coupled - chemistry emission model , various excitation processes controlling co cameron band and different atomic oxygen and atomic carbon emissions
have been modelled in comet 67p / churyumov - gerasimenko at 1.29 au ( perihelion ) and at 3 au heliocentric distances , which is being explored by esa s rosetta mission .
the intensities of co cameron band , atomic oxygen and atomic carbon emission lines as a function of projected distance are calculated for different co and co@xmath0 volume mixing ratios relative to water .
contributions of different excitation processes controlling these emissions are quantified .
we assess how co@xmath0 and/or co volume mixing ratios with respect to h@xmath0o can be derived based on the observed intensities of co cameron band , atomic oxygen , and atomic carbon emission lines .
the results presented in this work serve as base line calculations to understand the behaviour of low out - gassing cometary coma and compare them with the higher gas production rate cases ( e.g. comet halley ) .
quantitative analysis of different excitation processes governing the spectroscopic emissions is essential to study the chemistry of inner coma and to derive neutral gas composition . .
And you have already written the first three sentences of the full article: exploration of comets with space missions is critical to probe the coma and to access the detailed features of a cometary nucleus .
however , remote spectroscopic observations can provide ample information about the global composition of comets . the coma composition associated with main species
can be constrained from the analysis of airglow emissions using ground- and space - based telescopes ..
Please generate the next two sentences of the article | this nevertheless requires the quantitative assessment of physical processes that govern these emissions in the coma . among many observed cometary ultraviolet and visible airglow spectra
, metastable emission lines have gained special interest . |
8,154 | Suppose that you have an abstract for a scientific paper: the linear stability of mhd taylor - couette flow of infinite vertical extension is considered for liquid sodium with its small magnetic prandtl number pm of order of @xmath0 .
the calculations are performed for a container with @xmath1 with an axial uniform magnetic field excluding counter rotating cylinders .
the sign of the constant @xmath2 in the basic rotation law @xmath3 strongly influences the presented results .
it is negative for resting outer cylinder .
the main point here is that the subcritical excitation which occurs for large pm disappears for small pm ( cf .
fig .
[ minima ] ) .
this is the reason that the existence of the magnetorotational instability remained unknown over decades . for rotating outer cylinder
the limiting case @xmath4 ( i.e. @xmath5 ) plays an exceptional role .
the hydrodynamic instability starts to disappear while the hydromagnetic instability exists with minimal reynolds numbers at certain hartmann numbers of the magnetic field .
these reynolds numbers exactly scale with pm@xmath6 resulting in moderate values of order @xmath7 for pm=10@xmath8 .
however , already for the smallest positive value of @xmath2 the reynolds numbers start to scale as 1/pm leading to much higher values of order @xmath9 for pm=10@xmath8 .
hence , for outer cylinders rotating faster than the limit @xmath4 it is exclusively the _ magnetic _ reynolds number rm which directs the excitation of the instability .
they are resulting as lower for insulating walls ( ` vacuum ' ) than for conducting walls .
generally , the magnetic reynolds numbers for liquid sodium have to exceed values of order 10 leading to frequencies of about 20 hz for the rotation of the inner cylinder if containers with ( say ) 10 cm radius are considered .
the required magnetic fields are about 1000 gauss . also nonaxisymmetric modes have been considered . with vacuum boundary conditions
their excitation is always more difficult than the excitation of axisymmetric modes ; we never observed a....
And you have already written the first three sentences of the full article: the longstanding problem of the generation of turbulence in various hydrodynamically stable situations has found a solution in recent years with the mhd shear flow instability , also called magnetorotational instability ( mri ) , in which the presence of a magnetic field has a destabilizing effect on a differentially rotating flow with the angular velocity decreasing outwards .
the mri has been formulated decades ago @xcite for ideal taylor - couette flow , but its importance as the source of turbulence in accretion discs with differential ( keplerian ) rotation was first recognized by balbus and hawley , @xcite .
however , the mri has never been observed in the laboratory @xcite ..
Please generate the next two sentences of the article | after goodman and ji @xcite was the absence of mri due to the small magnetic prandtl number approximation used in @xcite .
the magnetic prandtl number pm is really very small under laboratory conditions ( @xmath10 and smaller , see table [ tab0 ] ) . |
8,155 | Suppose that you have an abstract for a scientific paper: it has recently been argued that if spacetime @xmath0 possesses non - trivial structure at small scales , an appropriate semi - classical description of it should be based on non - local bi - tensors instead of local tensors such as the metric @xmath1 .
two most relevant bi - tensors in this context are synge s world function @xmath2 and the van vleck determinant ( vvd ) @xmath3 , as they encode the metric properties of spacetime and ( de)focussing behaviour of geodesics .
they also characterize the leading short distance behavior of two point functions of the dalembartian @xmath4 .
+ + we begin by discussing the intrinsic and extrinsic geometry of _ equi - geodesic _ surfaces @xmath5 in a geodesically convex neighbourhood of an event @xmath6 , and highlight some elementary identities relating the vvd with geometry of @xmath7 . as an _ aside _
, we also comment on the contribution of @xmath7 to the surface term in the einstein - hilbert ( eh ) action and show that it can be written as a _ volume _ integral of @xmath8 . + + we then proceed to study the small scale structure of spacetime in presence of a lorentz invariant short distance cut - off @xmath9 using @xmath2 and @xmath3 , based on some recently developed ideas . we derive a @xmath10nd rank bi - tensor @xmath11 $ ] which naturally yields geodesic intervals bounded from below and reduces to @xmath12 for @xmath13 .
we present a general and mathematically rigorous analysis of short distance structure of spacetime based on ( a ) geometry of equi - geodesic surfaces @xmath7 of @xmath12 , ( b ) structure of the non local dalembartian @xmath14 associated with @xmath15 , and ( c ) properties of vvd .
in particular , we prove the following : ( i ) the ricci _ bi - scalar _ @xmath16 of @xmath15 is completely determined by @xmath7 , the tidal tensor and first two derivatives of @xmath3 , and has a non - trivial _ classical _ limit ( see text for details ) : @xmath17 ( ii ) the ghy term in eh action evaluated on equi - geodesic surfaces straddling....
And you have already written the first three sentences of the full article: quantum effects are expected to drastically affect the structure of space and time at the smallest of scales . however , our current theories of gravity and quantum mechanics are ( fortunately ) very stingy with the options they leave us as far as the small scale of structure of spacetime is concerned .
for example , attempts to model such a structure by violating or deforming lorentz invariance ( li ) are either very strongly constrained by experiments , or run into deeper conceptual issues when one goes beyond the simple one - particle models .
it is much more plausible that instead of li , it is the assumption of locality that might have to be given up at small scales @xcite ..
Please generate the next two sentences of the article | however , abandoning locality then also necessitates that we give up the classical description of spacetime in terms of local tensorial objects , in particular the metric tensor @xmath1 .
finding the right geometric variables that can describe spacetime geometry down to smallest scales is of utmost significant not only for quantum gravity , but also for the proper physical interpretation of the field equations of gravity at the classical level . |
8,156 | Suppose that you have an abstract for a scientific paper: we report the detection of radio emission and orbital motion from the nearby star - brown dwarf binary wise [email protected] .
radio observations across the 4.56.5ghz band with the very large array identify at the position of the system quiescent emission with a flux density of 15@xmath13 @xmath2jy , and a highly - polarized radio source that underwent a 23 min burst with peak flux density 300@xmath190 @xmath2jy .
the latter emission is likely a low - level magnetic flare similar to optical flares previously observed for this source .
no outbursts were detected in separate narrow - band h@xmath3 monitoring observations .
we report new high - resolution imaging and spectroscopic observations that confirm the presence of a co - moving t5.5 secondary and provide the first indications of three - dimensional orbital motion .
we used these data to revise our estimates for the orbital period ( 4.1@xmath4 yr ) and tightly constrain the orbital inclination to be nearly edge - on ( 93@xmath56@xmath6 ) , although robust measures of the component and system masses will require further monitoring .
the inferred orbital motion does not change the high likelihood that this radio - emitting very low - mass binary made a close pass to the sun in the past 100 kyr . .
And you have already written the first three sentences of the full article: wise [email protected] ( hereafter wise j0720@xmath00846 ) is an m9.5 dwarf originally identified by as a possible new member of the local 8 pc sample .
it was previously missed in searches for nearby low - mass dwarfs due to its low galactic latitude ( @xmath7 ) and small proper motion ( [email protected] mas yr@xmath8 ) .
subsequent follow - up observations by @xcite ; ( * ? ? ?.
Please generate the next two sentences of the article | * hereafter b15 ) ; and confirmed the late - type nature and proximity of the source ( [email protected] pc ) , and have identified it as having an unusually high recessional velocity ( + 83.8 km s@xmath8 ) , indicative of old disk / thick disk kinematics . @xcite
have deduced that wise j0720@xmath00846 had one of the closest stellar approaches to the sun inferred to date , passing within 0.25@xmath9 pc over a period of 60,00085,000 years ago , possibly penetrating the outer oort cloud . |
8,157 | Suppose that you have an abstract for a scientific paper: we study the stability of a compressible magnetic plane couette flow and show that compressibility profoundly alters the stability properties if the magnetic field has a component perpendicular to the direction of flow .
the necessary condition of a newly found instability can be satisfied in a wide variety of flows in laboratory and astrophysical conditions .
the instability can operate even in a very strong magnetic field which entirely suppresses other mhd instabilities .
the growth time of this instability can be rather short and reach @xmath0 shear timescales .
# 1@xmath1#1 .
And you have already written the first three sentences of the full article: instabilities of the magnetized shear flows play an important role in enhancing transport processes in various astrophysical bodies and laboratory experiments .
shear flows are rather common in astrophysics , and the study of their stability properties is important for the understanding of many phenomena in stars , jets , accretion flows , galaxies , etc .
likely , the best studied shear flow is differential rotation ..
Please generate the next two sentences of the article | it is well known since the classical papers by velikhov @xcite and chandrasekhar @xcite that a differentially rotating flow with a negative angular velocity gradient and a weak magnetic field can be subject to the magnetorotational instability .
this instability has been analyzed in detail in several astrophysical contexts ( @xcite ) because it can be responsible for transport of the angular momentum in various objects . in accretion disks , |
8,158 | Suppose that you have an abstract for a scientific paper: given a graph @xmath0 with a distinguished vertex @xmath1 , the critical group of @xmath2 is the cokernel of their reduced laplacian matrix @xmath3 . in this article
we generalize the concept of the critical group to the cokernel of any matrix with entries in a commutative ring with identity . in this article
we find diagonal matrices that are equivalent to some matrices that generalize the reduced laplacian matrix of the path , the cycle , and the complete graph over an arbitrary commutative ring with identity .
we are mainly interested in those cases when the base ring is the ring of integers and some subrings of matrices . using these equivalent diagonal matrices
we calculate the critical group of the @xmath4-cones of the @xmath5-duplications of the path , the cycle , and the complete graph . also , as byproduct , we calculate the critical group of another matrices , as the @xmath4-cones of the @xmath5-duplication of the bipartite complete graph with @xmath4 vertices in each partition , the bipartite complete graph with @xmath6 vertices minus a matching . .
And you have already written the first three sentences of the full article: let @xmath7 be a finite connected graph without loops , but with multiple edges allowed .
the _ adjacency matrix _ of @xmath0 , denoted by @xmath8 , is given by @xmath9 , where @xmath10 is the number of the edges between @xmath11 and @xmath12 in @xmath13 .
the _ laplacian matrix _ of @xmath0 is the matrix @xmath14 where @xmath15 and @xmath16 is the degree of the vertex @xmath11 in @xmath0 . if @xmath1 is a vertex of @xmath0 , the _ reduced laplacian matrix _ ,.
Please generate the next two sentences of the article | denoted by @xmath17 , is the matrix obtained from @xmath18 by removing the row and column @xmath1 .
critical group _ of @xmath0 , denoted by @xmath19 , is the cokernel of @xmath17 , @xmath20 where @xmath21 . |
8,159 | Suppose that you have an abstract for a scientific paper: if ray bursts have a cosmological origin , the sources are expected to trace the large scale structure of luminous matter in the universe .
i use a new likelihood method that compares the counts in cells distribution of ray bursts in the batse 3b catalog with that expected from the known large
scale structure of the universe , in order to place a constraint on the distance scale to cosmological bursts .
i find , at the 95% confidence level , that the comoving distance to the `` edge '' of the burst distribution is greater than @xmath0 mpc ( @xmath1 ) , and that the nearest burst is farther than @xmath2 mpc .
the median distance to the nearest burst is @xmath3 mpc , implying that the total energy released in rays during a burst event is of order @xmath4 erg .
none of the bursts that have been observed by batse are in nearby galaxies , nor is a signature from the coma cluster or the `` great wall '' likely to be seen in the data at present . .
And you have already written the first three sentences of the full article: the origin of ray bursts is still unknown and is currently the subject of a `` great debate '' in the astronomical community .
do the bursts have a galactic origin @xcite or are they cosmological @xcite ? and what is their distance scale ? in this paper ,
i do not attempt to answer the first question , but rather , i show that _ if _ one assumes that ray bursts are cosmological in origin , one can begin to answer the second question and place a constraint on the distance scale to the bursts ..
Please generate the next two sentences of the article | this is because cosmological bursts are expected to trace the large scale structure of luminous matter in the universe @xcite .
the constraint comes from comparing the _ expected _ clustering pattern of bursts on the sky which will depend on their distance scale because of projection effects with that _ actually observed_. the observed angular distribution is in fact quite isotropic @xcite ; hence , only a lower limit to the distance scale can be placed because a sufficiently large distance will always lead to a sufficiently isotropic distribution on the sky . here |
8,160 | Suppose that you have an abstract for a scientific paper: dynamical linked cluster expansions are linked cluster expansions with hopping parameter terms endowed with their own dynamics .
this amounts to a generalization from 2-point to point - link - point interactions .
we develop an associated graph theory with a generalized notion of connectivity and describe an algorithmic generation of the new .
we indicate physical applications to spin glasses , partially annealed neural networks and su(n ) gauge higgs systems .
in particular the new expansion technique provides the possibility of avoiding the replica - trick in spin glasses .
we consider variational estimates for the su(2 ) higgs model of the electroweak phase transition .
the results for the transition line , obtained by dynamical linked cluster expansions , agree quite well with corresponding high precision monte carlo results . .
And you have already written the first three sentences of the full article: linked cluster expansions ( lces ) have a long tradition in statistical physics . originally applied to classical fluids , later to magnetic systems ( @xcite,@xcite,@xcite and references therein ) , they were generalized to applications in particle physics in the eighties @xcite . there
they have been used to study the continuum limit of a lattice @xmath0 field theory in 4 dimensions at zero temperature . in @xcite
they were further generalized to field theories at finite temperature , simultaneously the highest order in the expansion parameter was increased to 18 . usually the analytic expansions are obtained as graphical expansions . because of the progress in computer facilities and the development of efficient algorithms for generating the graphs , it is nowadays possible to handle of the order of billions of graphs ..
Please generate the next two sentences of the article | the whole range from high temperatures down to the critical region becomes available , and thermodynamic quantities like critical indices and critical temperatures are determined with high precision ( the precision is comparable or even better than in corresponding high quality monte carlo results ) @xcite-@xcite .
an extension of lces to a finite volume in combination with a high order in the expansion parameter turned out to be a particularly powerful tool for investigating the phase structure of systems with first and second order transitions by means of a finite size scaling analysis @xcite . |
8,161 | Suppose that you have an abstract for a scientific paper: for a non - cyclic finite group @xmath0 , let @xmath1 denote the smallest number of conjugacy classes of proper subgroups of @xmath0 needed to cover @xmath0 .
bubboloni , praeger and spiga , motivated by questions in number theory , have recently established that @xmath2 and @xmath3 are bounded above and below by linear functions of @xmath4 . in this paper we show that if @xmath0 is in the range @xmath5 for @xmath6 , then @xmath7 . we give various alternative bounds , and derive explicit formulas for @xmath1 in some cases .
normal covering , linear group 20d50 , ( secondary ) 20g40 . .
And you have already written the first three sentences of the full article: let @xmath0 be a non - cyclic finite group .
we write @xmath1 for the smallest number of conjugacy classes of proper subgroups of @xmath0 needed to cover it . in other words
, @xmath1 is the least @xmath8 for which there exist subgroups @xmath9 such that @xmath10 we say that the set of conjugacy classes @xmath11 is a _.
Please generate the next two sentences of the article | normal covering _ for @xmath0 .
bubboloni and praeger @xcite have recently investigated @xmath1 in the case that @xmath0 is a finite symmetric or alternating group . |
8,162 | Suppose that you have an abstract for a scientific paper: in a recent paper [ beige , knight , and vitiello , quant - ph/0404160 ] , we showed that a large number @xmath0 of particles can be cooled very efficiently using a bichromatic interaction .
the particles should be excited by red - detuned laser fields while coupling to the quantized field mode inside a resonant and leaky optical cavity .
when the coupling constants are for all particles the same , a collective behavior can be generated and the cooling rate can be as large as @xmath1 times the single - particle coupling constants . here
we study the algebraic structure of the dynamics and the origin of the collective cooling process in more detail . .
And you have already written the first three sentences of the full article: collective features in the microscopic dynamics often lead to the emergence of surprising and unexpected effects in the evolution of a physical system at the macroscopic level @xcite .
the collective cooling of many two - level particles to very low temperatures is discussed here as an example of such a macroscopic manifestation of microscopic collective behavior @xcite .
it is shown that the collective behavior of a large number of particles can produce much higher cooling rates than they could be achieved by means of individual cooling based on the spontaneous decay of the individual particles @xcite ..
Please generate the next two sentences of the article | as in laser sideband cooling techniques for single two - level atoms @xcite , we consider an experimental setup , where red - detuned laser fields increase the excitation of the particles , thereby continuously reducing the number of phonons .
afterwards , the phonon energy can be removed constantly from the system . |
8,163 | Suppose that you have an abstract for a scientific paper: in this paper we firstly obtain two kinds of effective spectral density functions by setting the cut - off frequencies of baths be infinite and finite .
secondly , we investigate the reduced dynamics of open qubits in four kinds of systems constructed with the basic spin - boson model .
it is shown that the qubit has different dynamics governed by the two kinds of spectral density functions .
in addition , we obtained that a qubit coupled to an intermediate harmonic oscillator has longer decoherence and relaxation times as they are coupled to a common bath than to their respective baths . in solving the dynamics of qubits we use a numerically exact algorithm , iterative tensor multiplication algorithm based on the quasiadiabatic propagator path integral scheme . .
And you have already written the first three sentences of the full article: as a quantum system of interest interacts with its environment which is also considered being made up of a large number of the quantum particles , solving the dynamics of the total system is in fact an impossible task by now .
however , in many cases we are only interested in the dynamics of the quantum system of interest , thus we can investigate the reduced system by using the phenomenological environment as proposed by caldeira and leggett @xcite .
usually , in this method the environment is modelled by a bath of harmonic oscillators ( or other quantum particles ) and the influence of the bath on the quantum system is fully enclosed in the so - called spectral density function @xmath0 according to the characteristic of the environment one can choose the @xmath1 ohmic , sub - ohmic , super - ohmic forms and so on ..
Please generate the next two sentences of the article | thus , the reduced dynamics of the quantum systems can be investigated in detail .
many such problems have been treated extensively and some significative results have been obtained in the field in past years @xcite . |
8,164 | Suppose that you have an abstract for a scientific paper: classical optical interference experiments correspond to a measurement of the first - order correlation function of the electromagnetic field .
the converse of this statement : experiments that measure the first order correlation functions do not distinguish between the quantum and classical theories of light , does not always hold .
a counterexample is given .
# 1@xmath0#1 .
And you have already written the first three sentences of the full article: dirac s somewhat unfortunate statement about interference between two ( or more ) photons never occurring has led to fruitful discussions clarifying the understanding of interference from a quantum mechanical point of view .
these days textbook presentations elucidate that single photon light fields behave just like classical states of light @xcite when used in a young s double - slit interference experiment @xcite . to exhibit non - classical features , measurements which detect two- or more photon _ coincidences _
, phase sensitive measurements such as homodyning and quantum tomography @xcite , and waiting - time distribution ( anti - bunching ) measurements can be performed @xcite ..
Please generate the next two sentences of the article | single photon detection , however , i.e. intensity or first - order coherence measurements @xcite , are often held to be classical in character @xcite .
this conclusion stems from the analysis of young s interference patterns for single photon and glauber - coherent states of light @xcite , single photons emitted from two atoms @xcite and thermal fields @xcite . in these examples quantum and classical predictions for the form and visibility of interference patterns are identical @xcite . |
8,165 | Suppose that you have an abstract for a scientific paper: we study four particularly bright polarized compact objects ( tau a , virgo a , 3c273 and fornax a ) in the 7-year wmap sky maps , with the goal of understanding potential systematics involved in estimation of foreground spectral indices .
we estimate the spectral index , the polarization angle , the polarization fraction and apparent size and shape of these objects when smoothed to a nominal resolution of @xmath0 fwhm .
second , we compute the spectral index as a function of polarization orientation , @xmath1 . because these objects are approximately point sources with constant polarization angle , this function should be constant in the absence of systematics .
however , for the k- and ka - band wmap data we find strong index variations for all four sources .
for tau a , we find a spectral index of @xmath2 for @xmath3 , and @xmath4 for @xmath5 . on the other hand ,
the spectral index between ka- and q - band is found to be stable . a simple elliptical gaussian toy model with parameters matching those observed in tau a reproduces the observed signal , and shows that the spectral index is in particular sensitive to the detector polarization angle . based on these findings ,
we first conclude that estimation of spectral indices with the wmap k - band polarization data at @xmath0 scales is not robust .
second , we note that these issues may be of concern for ground - based and sub - orbital experiments that use the wmap polarization measurements of tau a for calibration of gain and polarization angles . .
And you have already written the first three sentences of the full article: one of the central goals in contemporary observational cosmology is to detect the postulated background of primordial gravity waves predicted by inflation .
the most direct observational signature of these gravity waves is a particular pattern in the polarization of the cosmic microwave background ( cmb ) known as b - modes .
the amplitude of these gravity waves is typically parametrized in terms of the tensor - to - scalar ratio , @xmath6 ( see , e.g. * ? ? ? * and references therein for a thorough review on inflation ) . during the last few years.
Please generate the next two sentences of the article | many experiments have been planned , built and fielded to measure @xmath6 , and the first relevant b - mode constraints have been already published by bicep ( @xmath7 , chiang et al .
2010 ) and quiet ( @xmath8 ; quiet 2011 , 2012 ) . |
8,166 | Suppose that you have an abstract for a scientific paper: the large mixing ( mass ) ( lma ) -msw model of solar neutrinos ( @xmath0 ) is now widely held to be near definitive , based on global consistency with data . no physical effect , however , compels its _ _ uniqueness__. the present search for an explicitly testable competitive model was stimulated by a surprising finding the high energy part of the standard solar model ( ssm ) @xmath1b @xmath2 spectrum can be scaled very precisely to observed flux levels _ without measurable shape distortion _ via sensitive combinations of long wavelength flavor conversion in vacuum and a @xmath3b @xmath2 flux @xmath4(b : ssm ) .
pursuantly , a new `` astroparticle '' model with the relatively specific parameters @xmath5ev@xmath6 ev@xmath7 ) ; sin@xmath8 0.580.56 ; @xmath9(b ) = 0.830.81@xmath10b : ssm ) coupled with modest changes in the ssm , offers a viable solution consistent with data . because kamland has set @xmath11m@xmath12ev@xmath13 , sin@xmath14 for _ _ anti__@xmath15-e scattering signals in the window 35 mev , even though the spectrum is flat above 5 mev .
this window is accessible to experiment for the first time in kamland .
new experiments are proposed to observe the more dramatic charged - current spectral effects .
r. s. raghavan bell laboratories , lucent technologies , murray hill nj 07974 usa infn
laboratori nazionali del gran sasso , italy .
And you have already written the first three sentences of the full article: experimental data on solar neutrinos ( @xmath16@xmath17)@xmath18 has accumulated rapidly in the last few years by the operation of several large detector facilities such as super - kamiokande ( sk ) , the sudbury neutrino observatory ( sno ) and kamland . the data from these detectors were precise and informative .
the neutral current signals ( nc ) from @xmath3b neutrinos in sno @xcite showed that @xmath16@xmath17 flavor was not conserved because the flavor - blind nc rate explicitly exceeded the charged current ( cc ) @xmath16@xmath17 signal rate .
the absolute nc rate was close to the @xmath3b @xmath16@xmath17 flux of the standard solar model ( ssm)@xcite . the ( @xmath16-electron ) scattering ( es ) signal in sk @xcite indicated the _ _ type _ _ of flavor conversion with a highly precise energy - independent es spectrum in the measured window 5 - 15 mev ..
Please generate the next two sentences of the article | this result severely restricted the possible @xmath16@xmath17 models .
global analyses of solar @xmath16@xmath17 data pinpointed matter conversion ( msw effect ) in the large mixing ( mass ) ( lma - msw ) regime as the most favored model of solar neutrinos@xcite . finally , kamland observed oscillations of _ _ terrestrial _ _ _ _ anti__neutrinos@xcite . |
8,167 | Suppose that you have an abstract for a scientific paper: we discuss a new monte carlo algorithm for the simulation of complex fluids .
this algorithm employs geometric operations to identify clusters of particles that can be moved in a rejection - free way .
it is demonstrated that this _ geometric cluster algorithm _ ( gca ) constitutes the continuum generalization of the swendsen
wang and wolff cluster algorithms for spin systems .
because of its nonlocal nature , it is particularly well suited for the simulation of fluid systems containing particles of widely varying sizes .
the efficiency improvement with respect to conventional simulation algorithms is a rapidly growing function of the size asymmetry between the constituents of the system .
we study the cluster - size distribution for a lennard - jones fluid as a function of density and temperature and provide a comparison between the generalized gca and the hard - core gca for a size - asymmetric mixture with yukawa - type couplings . .
And you have already written the first three sentences of the full article: the presence of multiple time and length scales constitutes one of the major problems in computer simulations of matter . in simulations that faithfully capture the dynamic evolution of a system , the fastest particles in the system
dictate the required time resolution .
if different types of particles with widely varying diffusion rates are present , then the slower particles may be unable to explore the entire configuration space during the course of the simulation , leading to ergodicity problems . in the computational study of complex fluids , such as colloidal suspensions ,.
Please generate the next two sentences of the article | this problem frequently occurs , since such systems typically contain particles of different sizes .
a concrete example is the ` nanoparticle haloing ' phenomenon discovered by lewis and coworkers @xcite . |
8,168 | Suppose that you have an abstract for a scientific paper: there are several mathematical models yielding @xmath0 noise . for example
, @xmath0 spectrum can be obtained from stochastic sequence of pulses having power - law distribution of pulse durations or from nonlinear stochastic differential equations .
we show that a couple of seemingly different models exhibiting @xmath0 spectrum are due to the similar scaling properties of the signals .
in addition , we demonstrate a connection between signals with the power - law behavior of the power spectral density generated by the nonlinear stochastic differential equations and modeled by a sequence of random different pulses .
an approximation of solutions of the nonlinear stochastic differential equations by the sequence of pulses correctly reproduces the power - law parts of the probability density function and of the power spectral density .
this connection provides further insights into the origin of @xmath0 noise .
_ keywords _ : stochastic processes ( theory ) , current fluctuations , stationary states .
And you have already written the first three sentences of the full article: signals having the power spectral density ( psd ) at low frequencies @xmath1 of the form @xmath2 with @xmath3 close to @xmath4 are commonly referred to as `` @xmath0 noise '' , `` @xmath0 fluctuations '' , or `` flicker noise .
'' power - law distributions of spectra of signals with @xmath5 , as well as scaling behavior are ubiquitous in physics and in many other fields @xcite . despite the numerous models and theories proposed since its discovery more than 80 years ago @xcite , the subject of @xmath0 noise remains still open for new discoveries .
most models and theories of @xmath0 noise are not universal because of the assumptions specific to the problem under consideration . a short categorization of the theories and models of @xmath0 noise is presented in the introduction of the paper @xcite ..
Please generate the next two sentences of the article | see also recent experimental investigations and physical models of @xmath0 noise in condensed matter @xcite and a review by balandin @xcite .
often @xmath0 noise is modeled as the superposition of lorentzian spectra with a wide range distribution of relaxation times @xcite . |
8,169 | Suppose that you have an abstract for a scientific paper: we derive constraints on the cosmic rays responsible for the be and part of the b observed in stars formed in the early galaxy : the cosmic rays can not be accelerated from the ism ; their energy spectrum must be relatively hard ( the bulk of the nuclear reactions should occur at @xmath030 mev / nucl ) ; and only 10@xmath1 erg / snii in high metallicity , accelerated particle kinetic energy could suffice to produce the be and b. the reverse snii shock could accelerate the particles . .
And you have already written the first three sentences of the full article: observations of stars of various metallicities [ @xmath2 @xmath3 ( fe / h)/(fe / h)@xmath4 have shown that the abundance ratios be / fe and b / fe do not vary appreciably over a broad range of @xmath2 ( e.g. duncan et al . 1996 ) . for @xmath2 less than about 0.1 , most of the fe is thought ( truran & timmes 1994 ) to be produced in type ii supernovae ( snii ) .
limiting our considerations to this range of metallicities , the constancy of b / fe and be / fe strongly suggest that b and be are also produced by processes related to sniis .
the accepted paradigm for the origin of most of the be is production in spallation reactions of accelerated particles ..
Please generate the next two sentences of the article | b , in addition to such reactions , is also produced in neutrino interactions in sniis ( woosley & weaver 1995 ) .
the observed be abundance as a function of metallicity can be approximated by @xmath5 ( duncan et al . |
8,170 | Suppose that you have an abstract for a scientific paper: in this paper , the dynamics of heuristic algorithms for constructing small vertex covers ( or independent sets ) of finite - connectivity random graphs is analysed . in every algorithmic step ,
a vertex is chosen with respect to its vertex degree .
this vertex , and some environment of it , is covered and removed from the graph .
this graph reduction process can be described as a markovian dynamics in the space of random graphs of arbitrary degree distribution .
we discuss some solvable cases , including algorithms already analysed using different techniques , and develop approximation schemes for more complicated cases .
the approximations are corroborated by numerical simulations . .
And you have already written the first three sentences of the full article: many questions of practical or scientific interest are based on combinatorial optimization problems whose numerical solution requires time resources growing exponentially with the system size , or more precisely , with the number of binary variables needed to encode the problem .
these include examples like planning and scheduling problems in various real - world applications , optimization of chip design , cryptografic systems in computer science , or glassy systems and random structures in physics .
all these problems are characterized by a non - trivial cost function , or energy , which has to be minimized over a large set of discrete degrees of freedom ..
Please generate the next two sentences of the article | the hardest of these optimization problems are collected in a class called _ np - hard _ @xcite .
hardness refers in this context to the exponential growth of the computational resolution time which is observed for all known numerical algorithms . despite an extremely large number of known np - hard problems , and numerous approaches to solve them , |
8,171 | Suppose that you have an abstract for a scientific paper: planetary nebula are useful kinematic tracers of the stars in all galaxy types .
i review recent observationally - driven developments in the study of galaxy mass profiles .
these have yielded surprising results on spiral galaxy disk masses and elliptical galaxy halo masses .
a key remaining question is the coupling between pne and the underlying stellar populations . .
And you have already written the first three sentences of the full article: planetary nebulae ( pne ) are of great importance in galaxy studies as _ unique _ observable proxies for stars in regions of low surface brightness .
they can be used to infer the spatial , kinematic , and chemical properties of the underlying stellar population , at distances of up to 100 mpc ( cf .
@xmath01 mpc for resolved stellar spectroscopy ) . here.
Please generate the next two sentences of the article | i review the use of pn kinematics to probe mass distributions in galaxies , with particular attention to disk masses of spiral galaxies ( [ sec : disk ] ) , and halo masses of elliptical galaxies ( [ sec : ell ] ) .
pn kinematics are also useful for studying angular momentum , orbit properties , and substructure in galaxies topics beyond the scope of this review . in all such dynamical studies , |
8,172 | Suppose that you have an abstract for a scientific paper: the geometry of d - branes can be probed by open string scattering .
if the background carries a non - vanishing b - field , the world - volume becomes non - commutative .
here we explore the quantization of world - volume geometries in a curved background with non - zero neveu - schwarz 3-form field strength @xmath0 . using exact and generally applicable methods from boundary conformal field theory
, we study the example of open strings in the su(2 ) wess - zumino - witten model , and establish a relation with fuzzy spheres or certain ( non - associative ) deformations thereof .
these findings could be of direct relevance for d - branes in the presence of neveu - schwarz 5-branes ; more importantly , they provide insight into a completely new class of world - volume geometries . + + .
And you have already written the first three sentences of the full article: it was observed by douglas and hull @xcite that d - branes on @xmath1 with a constant neveu - schwarz ( ns ) two - form potential @xmath2 give rise to an effective world - volume theory on a non - commutative torus .
even though this initial observation was re - considered and generalized by many authors @xcite , all the subsequent work is restricted to flat backgrounds . a perturbative analysis along the lines of @xcite
, on the other hand , shows that the quantization of world - volume geometries should be a much more general phenomenon which persists in the case of curved backgrounds . in this work we shall present the first non - perturbative ( in @xmath3 ) investigation of world - volume geometries in a curved string background with non - vanishing ns 3-form field @xmath0 . by the string s equation of motion . ].
Please generate the next two sentences of the article | an exact treatment of d - branes in curved backgrounds is possible within the framework of boundary conformal field theory .
here we illustrate the basic techniques and some general features of the resulting world - volume geometries in a particular example , namely the su(2 ) wzw theory , and study d - branes in the wzw model associated with the gluing condition @xmath4 . |
8,173 | Suppose that you have an abstract for a scientific paper: soft porous crystals are flexible metal organic frameworks that respond to physical stimuli such as temperature , pressure and gas adsorption by large changes in their structure and unit cell volume . while they have attracted a lot of interest , molecular simulation methods that directly couple adsorption and large structural deformations in an efficient manner are still lacking .
we propose here a new monte carlo simulation method based on non - boltzmann sampling in \{guest loading , volume } space using the wang landau algorithm , and show that it can be used to fully characterize the adsorption properties and the material s response to adsorption at thermodynamic equilibrium .
we showcase this new method on a simple model of the mil-53 family of breathing materials , demonstrating its potential and contrasting it with the pitfalls of direct , boltzmann simulations .
we furthermore propose an explanation for the hysteretic nature of adsorption in terms of free energy barriers between the two metastable host phases . .
And you have already written the first three sentences of the full article: a new field of research has emerged in the past decade in the context of solid - state chemistry and physical chemistry .
it is the science of metal organic frameworks ( mof s ) .
metal organic frameworks , also called _ porous coordination polymers _.
Please generate the next two sentences of the article | ( pcp s ) , are hybrid crystalline porous materials consisting of metallic species connected to one another with organic linkers .
they display an extremely large range of crystal structures and host - guest properties , which makes them an important class of materials with potentially major impact in adsorption / separation technologies of strategic gas linked with energy supply and environmental problems . |
8,174 | Suppose that you have an abstract for a scientific paper: the bounds on the neutrino mixing angles and cp dirac phase for an @xmath0 model with lopsided mass matrices , arising from the presence of @xmath1 and @xmath2 higgs representations , are studied by variation of the one real and three unknown complex input parameters for the right - handed majorana neutrino mass matrix .
the scatter plots obtained favor nearly maximal atmospheric neutrino mixing , while the reactor neutrino mixing lies in the range @xmath3 with values greater than @xmath4 most densely populated . a rather compelling scenario within the model follows , if we restrict the three unknown complex parameters to their imaginary axes and set two of them equal .
we then find the scatter plots are reduced to narrow bands , as the mixing angles and cp phase become highly correlated and predictive .
the bounds on the mixing angles and phase then become @xmath5 , @xmath6 , @xmath7 , and @xmath8 . moreover , successful leptogenesis and subsequent baryogenesis are also obtained , with @xmath9 increasing from @xmath10 as @xmath11 increases from 0.45 to 0.55 .
fermilab - pub-05 - 021-t + hep - ph/0502161 + may 2005 + .
And you have already written the first three sentences of the full article: since the discovery of atmospheric neutrino oscillations @xcite , more recently that of solar neutrino oscillations @xcite , and still more recently confirmation of these two types of neutrino oscillations with accelerator- and reactor - produced neutrinos @xcite , many models have been proposed in the literature to explain the mass and mixing parameters associated with these oscillations @xcite .
( we have cited just the most recent references for those experiments and several review articles for the models proposed . )
some models restrict their scope to the lepton sector , while others such as grand unified models are more ambitious and attempt to explain the masses and mixings in both the lepton and quark sectors ..
Please generate the next two sentences of the article | the textures for the mass matrices obtained in the models may be simply postulated at the outset , derived from the observed mixing matrix with a diagonal charged lepton mass matrix , obtained from a certain unification group in conjunction with a well - defined family symmetry , or rely solely on the clebsch - gordon coefficients of that group . until now
, all viable models for the lepton sector have only had to explain the apparent near maximal @xmath12 mixing angle for the atmospheric neutrinos and the less than maximal @xmath13 large mixing angle ( lma ) solution for the solar neutrinos , while satisfying the two observed mass squared differences , @xmath14 and @xmath15 , and the upper bound for the still unobserved @xmath16 mixing angle . on the other hand , the neutrino mass hierarchy ( normal or inverted ) , the majorana vs dirac nature of the neutrinos , the appropriate values for @xmath16 and the cp - violating phases ( one dirac and two majorana ) remain undetermined experimentally . with the next more precise round of neutrino oscillation experiments which will restrict some of the unknowns , many of the more quantitative models proposed |
8,175 | Suppose that you have an abstract for a scientific paper: we report significant associated clustering in the field of a @xmath0 quasar from the clowes - campusano lqg in the form of both a factor @xmath1 overdensity of @xmath2 galaxies , and red sequences of 1518 galaxies at @xmath3 indicative of a population of massive ellipticals at the quasar redshift .
the quasar is located between two groups of these galaxies , with further clustering extending over .
a band of @xmath4 galaxies bisects the two groups of red sequence galaxies , and we suggest that the merging of these two groups has triggered both this band of star - formation and the quasar . # 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: quasars have been used as efficient probes of high - redshift clustering because they are known to favour rich environments .
quasars may also trace large - scale structures at early epochs ( @xmath5 ) in the form of large quasar groups ( lqgs ) , which have comparable sizes to the largest structures at the present epoch .
the largest of these is the clowes - campusano lqg of 18 quasars at @xmath6 , with a maximal extent of 200@xmath7mpc ( clowes & campusano 1991 ) . to examine the galaxy environment of quasars in this lqg ,.
Please generate the next two sentences of the article | we have conducted an ultra - deep optical ( to @xmath8 ) study of a @xmath9 field containing 3 quasars from this lqg , with additional @xmath10 imaging obtained for subfields around 2 of them .
any associated passively - evolving galaxies can be identified from their extremely - red optical - ir colours ( @xmath11 ) . |
8,176 | Suppose that you have an abstract for a scientific paper: in the near future there will be launched space missions ( e.g. corot , kepler ) , designed to detect earth - like extrasolar planets .
the orbital elements of these ( still hypothetic ) planets will contain some uncertainties , that can only be eliminated by careful dynamical investigations of the hosting planetary systems .
the proportion of extrasolar planetary systems with one known giant planet is high ( @xmath0 ) , therefore as a first step we have investigated the possible existence of terrestrial planets in these systems . in this paper a development of a stability catalogue of the habitable zones of exoplanetary systems is reported .
this catalogue is formed by a series of stability maps , which can help to establish , where earth - like planets could exist in extrasolar planetary systems having one giant planet . after a description of the dynamical model and the numerical methods , details of the stability maps
are discussed .
an application of the stability catalogue to 15 known exoplanetary systems is also shown , and a characterization of the stability properties of their habitable zones is given .
[ firstpage ] astrobiology celestial mechanics methods : numerical ( stars : ) planetary systems . .
And you have already written the first three sentences of the full article: since the discovery of the first extrasolar planet around a solar - type star , 51 pegasi by @xcite , by now ( october 2006 ) 209 exoplanets have been found .
these planets form 179 exoplanetary systems , among which there are 21 multiple systems .
the main detection technique of exoplanets is based on the doppler shift of the hosting star s spectral lines ..
Please generate the next two sentences of the article | this method is adequate to discover giant planets , but it is not yet capable to detect earth - sized planets .
however , the detection and investigation of earth - like exoplanets can be of great importance for the further improvements of formation theories of our solar system , where both rocky earth - like , and gaseous jupiter - like planets have been formed . |
8,177 | Suppose that you have an abstract for a scientific paper: a new algebraic cubature formula of degree @xmath0 for the product chebyshev measure in the @xmath1-cube with @xmath2 nodes is established . the new formula
is then applied to polynomial hyperinterpolation of degree @xmath3 in three variables , in which coefficients of the product chebyshev orthonormal basis are computed by a fast algorithm based on the 3-dimensional fft .
moreover , integration of the hyperinterpolant provides a new clenshaw - curtis type cubature formula in the 3-cube . .
And you have already written the first three sentences of the full article: a cubature formula with high accuracy is an important tool for numerical computation and has various applications .
one of the applications is to construct polynomial hyperinterpolation , introduced by sloan @xcite , which is an approximation process constructed by applying the cubature formula on the fourier coefficients of the orthogonal projection operator . a cubature formula of degree @xmath4 with @xmath5 nodes with respect to a measure @xmath6 supported on a set @xmath7 takes the form @xmath8 where @xmath9 , called weights , are ( positive ) numbers , @xmath10 is a set of points , called nodes , @xmath11 with @xmath12 , and @xmath13 denoted the subspace of @xmath1-variate polynomials of total degree @xmath14 restricted to @xmath7 . for a cubature formula of degree @xmath4 to exist ,
it is necessary that @xmath15 there are improved lower bounds of the same order in terms of @xmath3 ..
Please generate the next two sentences of the article | a challenging problem is to construct cubature formulae with fewer nodes , that is , with the number of nodes @xmath5 close to the lower bound .
in this paper we consider the case that the measure is given by the product chebyshev weight function @xmath16 on the cube @xmath17^d$ ] . for @xmath18 , the gaussian quadrature formula of degree |
8,178 | Suppose that you have an abstract for a scientific paper: neutrino interactions recorded in a 5.1 fiducial kiloton - year exposure of the soudan-2 iron tracking calorimeter are analyzed for effects of neutrino oscillations .
using contained single track and single shower events , we update our measurement of the atmospheric @xmath0/@xmath1 ratio - of - ratios and find @xmath2 . assuming this anomalously low r - value is the result of @xmath0 flavor disappearance via @xmath0 to @xmath3 oscillation , we select samples of charged current events which offer good resolution , event - by - event , for @xmath4 reconstruction .
oscillation - weighted monte carlo events are fitted to these data events using a @xmath5 function summed over bins of log@xmath6 .
the region allowed in the ( @xmath7 , @xmath8 ) plane at 90% cl is obtained using the feldman - cousins procedure : @xmath9 and @xmath10 .
a small but relatively energetic sample of partially contained @xmath0 events has also been isolated .
their distribution in log@xmath11 relative to null oscillation monte carlo is compatible with @xmath0 to @xmath3 oscillation scenarios within the parameters region allowed by our contained events . .
And you have already written the first three sentences of the full article: the soudan-2 experiment is currently taking data using its fine - grained iron tracking calorimeter of total mass 963 tons . this detector images non - relativistic as well as relativistic charged particles produced in atmospheric neutrino reactions .
it is operating underground at a depth of 2100 meters - water - equivalent on level 27 of the soudan mine state park in northern minnesota ( northwest of sudbury ) .
the calorimeter s modular design enabled data - taking to commence in april 1989 when the detector was one quarter of its full size ; assembly of the detector was completed during 1993 ..
Please generate the next two sentences of the article | data - taking has continued with 85% live time , even though dynamite blasting has been underway nearby for the minos cavern excavation since summer 1999 .
the data exposure as of this conference is 5.40 fiducial kiloton - years ( kty ) . |
8,179 | Suppose that you have an abstract for a scientific paper: purpose : : beam range control is the essence of radiotherapy with heavy charged particles . in conventional broad - beam delivery , fine range adjustment is achieved by insertion of range shifting and compensating materials . in dosimetry , solid phantoms are often used for convenience .
these materials should ideally be equivalent to water . in this study , we evaluated dosimetric water equivalence of four common plastics , hdpe , pmma , pet , and pom . methods : : using the bethe formula for energy loss , the gottschalk formula for multiple scattering , and the sihver formula for nuclear interactions , we calculated the effective densities of the plastics for these interactions .
we experimentally measured variation of the bragg peak of carbon - ion beams by insertion of hdpe , pmma , and pom , which were compared with analytical model calculations .
results : : the theoretical calculation resulted in slightly reduced multiple scattering and severely increased nuclear interactions for hdpe , compared to water and the other plastics . the increase in attenuation of carbon ions for 20-cm range shift
was experimentally measured to be 8.9% for hdpe , 2.5% for pmma , and 0.0% for pom while pet was theoretically estimated to be in between pmma and pom .
the agreement between the measurements and the calculations was about 1% or better .
conclusions : : for carbon - ion beams , pom was dosimetrically indistinguishable from water and the best of the plastics examined in this study . the poorest was hdpe , which would reduce the bragg peak by 0.45% per cm range shift , although with marginal superiority for reduced multiple scattering
. between the two clear plastics , pet would be superior to pmma in dosimetric water equivalence . .
And you have already written the first three sentences of the full article: the essence of radiotherapy with heavy charged particles is its intrinsic capability of three - dimensional dose formation with a bragg peak at the beam range , which can be precisely controlled by adapting the beam energy incident on a patient . in conventional broad - beam delivery,@xcite
a range shifter degrades excessive beam energy and a range compensator fills target - depth deficit varying in the field to best conform the spread - out bragg peak to a planning target volume.@xcite a range shifter is typically a composite of plates of precisely controlled thickness and a range compensator is a physical filter custom - made for an individual field .
their material should be uniform , stable , machinable , inexpensive , and ideally equivalent to water , which is the reference material for dosimetry ..
Please generate the next two sentences of the article | these requirements are also valid for solid phantom materials , which are used when water - phantom dosimetry is not possible or convenient . to estimate the effective thickness of a material by the resultant range shift in water , an effective density
is assigned for the material . however , this approximation may cause dosimetric errors due to alteration of the radiation because the effective density differs for multiple scattering and nuclear interactions.@xcite dosimetric water equivalence , which is evaluated by uniformity of effective densities for relevant interactions , is essential to energy degrading of charged - particle beams for range shifting , range compensation , and dosimetry . |
8,180 | Suppose that you have an abstract for a scientific paper: we systematically analyze all the available x - ray spectra of disc accreting neutron stars ( atolls and millisecond pulsars ) from the _ rxte _ database .
we show that while these all have similar spectral evolution as a function of mass accretion rate , there are also subtle differences .
there are two different types of hard / soft transition , those where the spectrum softens at all energies , leading to a diagonal track on a colour - colour diagram , and those where only the higher energy spectrum softens , giving a vertical track .
the luminosity at which the transition occurs is _ correlated _ with this spectral behaviour , with the vertical transition at @xmath0 while the diagonal one is at @xmath1 .
superimposed on this is the well known hysteresis effect , but we show that classic , large scale hysteresis occurs only in the outbursting sources , indicating that its origin is in the dramatic rate of change of mass accretion rate during the disc instability . we show that the long term mass accretion rate correlates with the transition behaviour , and speculate that this is due to the magnetic field being able to emerge from the neutron star surface for low average mass accretion rates .
while this is not strong enough to collimate the flow except in the millisecond pulsars , its presence may affect the inner accretion flow by changing the properties of the jet .
= -0.5 cm [ firstpage ] accretion , accretion discs x - rays : binaries , atoll sources .
And you have already written the first three sentences of the full article: neutron stars represent the most dense form of matter known before black hole formation .
the equation of state of such material is not well understood but typical expected size scales of @xmath2 km for a @xmath3 object give @xmath4 similar to that of the last stable orbit around a schwarzschild black hole .
the gravitational potential seen by the accreting material is then very similar in neutron stars and black holes , but with the obvious difference that the material may then fall seamlessly and invisibly from the edge of the disc through the event horizon in the black holes ( but see e.g. krolik , hawley & hirose 2005 for an alternative view ) , but must impact onto the solid surface for the neutron stars ..
Please generate the next two sentences of the article | this boundary layer emission should give a clear distinction between the two types of systems , yet in practice it can be quite hard to discriminate between the disc accreting , low magnetic field neutron stars and galactic black holes ( gbh ) . both show hard spectra at low mass accretion rates ( e.g. barret & vedrenne 1994 ; barret et al .
2000 ) while at higher mass accretion rates the black holes can show low temperature , optically thick comptonized emission from a corona which can look similar to an optically thick boundary layer in the neutron stars systems ( the black hole ` very high state ' , done & gierliski 2003 , hereafter dg03 ) . |
8,181 | Suppose that you have an abstract for a scientific paper: herein we report on the thermal expansions and temperature - dependent crystal structures of select ternary carbide max phases in the ti
al c phase diagram in the 1001000@xmath0c temperature range .
a bulk sample containing @xmath1 wt.% ti@xmath2al@xmath3c@xmath4 ( `` 523 '' ) , @xmath5 wt.% ti@xmath3alc ( `` 211 '' ) , @xmath6 wt.% ti@xmath4alc@xmath3 ( `` 312 '' ) , and @xmath7 wt.% ( ti@xmath8al@xmath8)al is studied by rietveld analysis of high - temperature neutron diffraction data .
we also report on the same for a single - phase sample of ti@xmath4alc@xmath3 for comparison .
the thermal expansions of all the max phases studied are higher in the @xmath9 direction than in the @xmath10 direction .
the bulk expansion coefficients
9.3(@xmath11 ) @xmath12 k@xmath13 for ti@xmath2al@xmath3c@xmath4 , 9.2(@xmath11 ) @xmath12 k@xmath13 for ti@xmath3alc , and 9.0(@xmath11 ) @xmath12 k@xmath13 for ti@xmath4alc@xmath3 are comparable within one standard deviation of each other . in ti@xmath2al@xmath3c@xmath4 , the dimensions of the ti
c octahedra for the 211-like and 312-like regions are comparable to the ti
c octahedra in ti@xmath3alc and ti@xmath4alc@xmath3 , respectively .
the isotropic mean - squared atomic displacement parameters are highest for the al atoms in all three phases , and the values predicted from first - principles phonon calculations agree well with those measured . .
And you have already written the first three sentences of the full article: titanium carbide is one the hardest transition metal binary carbides known , which renders it resistant to wear and makes it a favorable material for applications such as drill bits and cutting tools . with a melting point of over 3000@xmath0c , it is thermally quite stable .
however , transition metal binary carbides are brittle , difficult to machine , and highly susceptible to thermal shock .
the ternary carbides known as @xmath14 ( max ) phases @xcite ( where @xmath15 = 1,2 , or 3 and @xmath16 is a transition metal , @xmath17 is a group a element mostly from groups 13 and 14 , and @xmath18 is either c or n ) often overcome some of these shortcomings , while still being heat tolerant . as a class , the max phases have unusual yet attractive and often unique combinations of properties that bring together some of the best attributes of ceramics and metals @xcite . like metals , they are excellent electric and thermal conductors , with exceptional thermal shock resistance and damage tolerance @xcite . in some cases , they are creep @xcite , oxidation @xcite , and fatigue @xcite resistant ..
Please generate the next two sentences of the article | furthermore , they are elastically quite stiff , yet readily machinable @xcite . in this work
we are interested in the max phases in the ti |
8,182 | Suppose that you have an abstract for a scientific paper: the bose - hubbard model exhibits a rich phase diagram consisting both of insulating regimes where diagonal long range ( solid ) order dominates as well as conducting regimes where off diagonal long range order ( superfluidity ) is present . in this paper
we describe the results of quantum monte carlo calculations of the phase diagram , both for the hard and soft core cases , with a particular focus on the possibility of simultaneous superfluid and solid order .
we also discuss the appearance of phase separation in the model .
the simulations are compared with analytic calculations of the phase diagram and spin wave dispersion . .
And you have already written the first three sentences of the full article: a lot of attention has been focussed on the interacting electron problem in the last several decades , whereas the interacting boson problem has been considered more often in the framework of specific applications only .
however , there are a number of important situations where the elementary excitations are either intrinsically bosonic in character or else can usefully be viewed in terms of bosonic models .
@xmath0 is an example of the former situation,@xcite while quantum spin systems,@xcite granular superconductors,@xcite and flux lines in type .
Please generate the next two sentences of the article | ii superconductors@xcite are examples of the latter .
therefore it is important to understand in detail the features of model boson systems , in much the same way that one studies the hubbard , anderson , and t - j hamiltonians for correlated fermions . in this paper |
8,183 | Suppose that you have an abstract for a scientific paper: this paper addresses the problem of large - scale image retrieval .
we propose a two - layer fusion method which takes advantage of global and local cues and ranks database images from coarse to fine ( c2f ) .
departing from the previous methods fusing multiple image descriptors simultaneously , c2f is featured by a layered procedure composed by filtering and refining . in particular , c2f consists of three components .
1 ) distractor filtering . with holistic representations ,
noise images are filtered out from the database , so the number of candidate images to be used for comparison with the query can be greatly reduced .
2 ) adaptive weighting . for a certain query
, the similarity of candidate images can be estimated by holistic similarity scores in complementary to the local ones .
3 ) candidate refining .
accurate retrieval is conducted via local features , combining the pre - computed adaptive weights .
experiments are presented on two benchmarks , _
i.e. , _ holidays and ukbench datasets .
we show that our method outperforms recent fusion methods in terms of storage consumption and computation complexity , and that the accuracy is competitive to the state - of - the - arts .
shell : bare demo of ieeetran.cls for ieee journals image retrieval , coarse - to - fine , holistic representation , local feature . .
And you have already written the first three sentences of the full article: paper considers the task of accurate image retrieval on a large scale . given a query image , we aim at finding the similar images from the database . a number of retrieval models have been proposed in this scenario , among which local feature based model , _
i.e. _ , bag - of - words ( bow ) @xcite , has obtained widespread applications .
nevertheless , traditional bow is lack of spatial layout and may encounter quantization errors . besides , local feature.
Please generate the next two sentences of the article | based models usually lead to huge storage consumption , which is limited in real - world applications featured by the rapid expansion of the image volume . on the contrary ,
holistic representations such as hsv represent an image via global vectors and obtain good scalability , while the retrieval accuracy is less desirable . generally speaking , |
8,184 | Suppose that you have an abstract for a scientific paper: let @xmath0 be a simple graph of order @xmath1 .
the total dominating set is a subset @xmath2 of @xmath3 that every vertex of @xmath3 is adjacent to some vertices of @xmath2 .
the total domination number of @xmath4 is equal to minimum cardinality of total dominating set in @xmath4 and denoted by @xmath5 .
the total domination polynomial of @xmath4 is the polynomial @xmath6 , where @xmath7 is the number of total dominating sets of @xmath4 of size @xmath8 .
let @xmath4 be a connected graph constructed from pairwise disjoint connected graphs @xmath9 by selecting a vertex of @xmath10 , a vertex of @xmath11 , and identify these two vertices .
then continue in this manner inductively .
we say that @xmath4 is obtained by point - attaching from @xmath12 and that @xmath13 s are the primary subgraphs of @xmath4 . in this paper
, we consider some particular cases of these graphs that most of them are of importance in chemistry and study their total domination polynomials .
department of mathematics , yazd university , 89195 - 741 , yazd , iran + [email protected] + * keywords : * total domination number , total domination polynomial , total dominating set . * ams subj . class .
: * 05a18 ; 11b 73 , 05c12 . .
And you have already written the first three sentences of the full article: let @xmath0 be a simple graph of order @xmath1 . for any vertex @xmath14 , the open neighborhood of @xmath15 is the set @xmath16 and the closed neighborhood is the set @xmath17=n ( v ) \cup \{v\}$ ] . for a set @xmath18 ,
the open neighborhood of @xmath19 is the set @xmath20 and the closed neighborhood of @xmath19 is the set @xmath21=n ( s ) \cup s$ ] .
a set @xmath22 is a total dominating set if every vertex of @xmath3 is adjacent to some vertices of @xmath2 , or equivalently , @xmath23 ..
Please generate the next two sentences of the article | the total dominating number @xmath5 is the minimum cardinality of a total dominating set in @xmath4 .
a total dominating set with cardinality @xmath5 is called a @xmath24-set . |
8,185 | Suppose that you have an abstract for a scientific paper: we investigate the transport of brownian particles in a two - dimensional potential under the action of a uniform external force .
the potential is periodic in one direction and confines the particle to a narrow channel of varying cross - section in the other direction .
we apply the standard long - wave asymptotic analysis in the narrow dimension and show that the leading order term is equivalent to that obtained previously from a direct extension of the fick - jacobs approximation .
we also show that the confining potential has similar effects on the transport of brownian particles to those induced by a solid channel .
finally , we compare the analytical results with brownian dynamics simulations in the case of a sinusoidal variation of the width of the parabolic potential in the cross - section .
we obtain excellent agreement for the marginal probability distribution , the average velocity of the brownian particles and the asymptotic dispersion coefficient , over a wide range of pclet numbers . .
And you have already written the first three sentences of the full article: recent progress in microfluidic devices has led to the development of novel separation strategies that take advantage of the unprecedented control on the geometry and chemistry of the stationary phase at scales that are comparable to the size of the transported species @xcite .
a fundamental problem that is at the core of several of the proposed separation devices is the transport of brownian particles through entropy barriers .
a representative example is the motion of a suspended particle in a channel with periodically varying cross section ..
Please generate the next two sentences of the article | the purely - diffusive transport in the absence of an external force has been studied extensively @xcite , and a well - known approach is to reduce the dimensionality of the problem via the fick - jacobs approximation . in this approximation
the motion in the cross section is reduced to an entropic contribution to the longitudinal transport @xcite . |
8,186 | Suppose that you have an abstract for a scientific paper: large fluctuations of conductivity with time are observed in a low - mobility two - dimensional electron system in silicon at low electron densities @xmath0 and temperatures . a dramatic increase of the noise power ( @xmath1 ) as @xmath0
is reduced below a certain density @xmath2 , and a sharp jump of @xmath3 at @xmath4 , are attributed to the freezing of the electron glass at @xmath5 .
the data strongly suggest that glassy dynamics persists in the metallic phase .
glassy dynamics , metal - insulator transition 71.30.+h , 73.50.td , 73.40.qv .
And you have already written the first three sentences of the full article: the metal - insulator transition ( mit ) in two dimensions ( 2d ) has been a subject of intensive research in recent years [ 1 ] but the physics behind this phenomenon is still not understood .
it has been established , however , that it occurs in the regime where both coulomb ( electron - electron ) interactions and disorder are strong .
the competition between these two effects has been suggested [ 2 ] to lead to glassy dynamics ( electron or coulomb glass ) ..
Please generate the next two sentences of the article | therefore , it has been proposed that the 2d mit can be described alternatively as the melting of the wigner glass [ 3 ] , or the melting of the coulomb glass [ 4 ] .
the existence of a large number of metastable states in a glass results in fluctuations of conductivity @xmath6 with time ( conductivity noise ) so that mesoscopic samples should be more suitable for studies of glassy properties . |
8,187 | Suppose that you have an abstract for a scientific paper: data from spacecrafts tracking exhibit many anomalies that suggest the dependence of the speed of electromagnetic radiation with the motion of its source .
this dependence is different from that predicted from emission theories that long ago have been demonstrated to be wrong . by relating the velocity of light and the corresponding doppler effect with the velocity of the source at the time of detection , instead of the time of emission , it is possible to explain quantitatively and qualitatively the spacecraft anomalies . also , a formulation of electromagnetism compatible with this conception is possible ( and also compatible with the known electromagnetic phenomena ) . under this theory
the influence of the velocity of the source in the speed of light is somewhat subtle in many practical situations and probably went unnoticed in other phenomena . .
And you have already written the first three sentences of the full article: in these lines i intend to show that there exists consistent evidence pointing to the need of revision and further study of what seem at present a settled issue , namely the independence of the speed of electromagnetic radiation on the motion of its source . the main point in
the evidence is the range disagreement during the earth flyby of the spacecraft near in 1998 .
its range was measured near the point of closest approach using two radar stations of the space surveillance network ( ssn ) , and compared with the trajectory obtained from the deep space network ( dsn)@xcite . as for the range , the two measurements should match within a meter - level accuracy ( the resolution is 5 m for millstone and 25 m for altair ) , but actual data showed a difference that varies linearly with time ( with different slopes for the two radar stations ) up to a maximum difference of about 1 km , i.e. more than 100 times larger than the accuracy of the equipment used ( see figure 10 of @xcite ) ..
Please generate the next two sentences of the article | further , when near crossed the orbits of gps satellites ( orbital radius 26,600 km ) the measured range difference was 650 m , that is , a time difference of 2 @xmath0s .
is it reasonable that any standard gps receiver performs better than dsn or ssn ? |
8,188 | Suppose that you have an abstract for a scientific paper: we examine the global structure of scalar field critical collapse spacetimes using a characteristic double - null code .
it can integrate past the horizon without any coordinate problems , due to the careful choice of constraint equations used in the evolution .
the limiting sequence of sub- and supercritical spacetimes presents an apparent paradox in the expected penrose diagrams , which we address in this paper .
we argue that the limiting spacetime converges pointwise to a unique limit for all @xmath0 , but not uniformly .
the @xmath1 line is different in the two limits .
we interpret that the two different penrose diagrams differ by a discontinuous gauge transformation .
we conclude that the limiting spacetime possesses a singular event , with a future removable naked singularity . .
And you have already written the first three sentences of the full article: the critical collapse of scalar fields gives rise to a new class of thought experiments in general relativity @xcite .
it has been suggested that a weak singularity may be visible to a distant observer during the collapse of a scalar field @xcite . with the presence of such potentially problematic phenomena
, one can ask to what degree cosmic censorship is violated ..
Please generate the next two sentences of the article | the spirit of the cosmic censorship conjecture is that the evolution of spacetimes as seen by distant observers in asymptotically flat regions is determined uniquely by the einstein equations .
if visible infinite curvature arises in the evolution from regular initial data , one might have cause for concern about the classical completeness of einstein s theory of gravity . |
8,189 | Suppose that you have an abstract for a scientific paper: we present our model to interpret the sed of galaxies . the model for the uv to sub - mm
sed is already well established @xcite .
we remind here its main features and show some applications .
recently we have extended the model to the radio range @xcite , and we have started to include the x - ray emission from the stellar component . .
And you have already written the first three sentences of the full article: we have developed a model ( grasil , _ http://grana.pd.astro.it_ ) for the sed of galaxies including dust effects @xcite .
we consider a geometry more complex and realistic than previous treatments , and take into account 3 distinct environments where stellar radiation interacts with dust ( figure [ cartoon2f_mc ] ) : ( 1 ) * molecular clouds ( mcs ) + young stars * ( clumped component ) , ( 2 ) * diffuse ism ( cirrus ) + older stars * ( diffuse component ) , ( 3 ) agb envelopes ( included in the ssp library , bressan et al . , 1998 ) . therefore both stars and dust have a _ realistic 2-phase distribution_. the association between young stars and mcs is modelled to mimic the birth of stars in mcs and their gradual escape as they grow old : the fraction of each ssp energy radiated inside mcs is decreased with its age ( figure [ cartoon2f_mc ] ) .
it is the first time that such an _ age - dependent or selective extinction _ is modelled ( see granato et al ..
Please generate the next two sentences of the article | , 2000 for interesting applications ) .
the dust model consists of normal grains in thermal equilibrium , small grains fluctuating in temperature and pah molecules . |
8,190 | Suppose that you have an abstract for a scientific paper: this article is an overview of recent experimental and theoretical work on transport in phase - coherent hybrid nanostructures , with particular emphasis on dc electrical conduction .
a summary of multiple scattering theory and the quasi - classical methods is presented and comparisons between the two are made .
several paradigms of phase - coherent transport are discussed , including zero - bias anomalies , reentrant and long range proximity effects , andreev interferometers and superconductivity - induced conductance suppression . .
And you have already written the first three sentences of the full article: during the past few years , phase - coherent quasi - particle transport in hybrid superconducting structures has emerged as a new field of study , bringing together the hitherto separate areas of superconductivity and mesoscopic physics [ altshuler , lee and webb 1991 , buot 1993 ] .
the seeds of this new field of research were sown for a variety of different reasons .
the search for novel devices led several groups to embark on experimental programmes aimed at exploring the properties of hybrid semiconducting - superconducting structures . during the 1980s.
Please generate the next two sentences of the article | there had been great progress in understanding transport properties of normal sub - micron conductors and therefore towards the end of that decade , it seemed natural to ask how these were affected by the presence of superconductivity .
partly as a consequence of formidable technological problems to be overcome in growing hybrid nanostructures , the first experimental results did not emerge until the summer of 1991 , when two groups [ petrashov and antonov 1991 , kastalskii et al 1991 ] independently submitted papers on phase - coherent transport in sub - micron superconducting structures . |
8,191 | Suppose that you have an abstract for a scientific paper: helium atom scattering ( has ) studies of the h - covered mo(110 ) and w(110 ) surfaces reveal a twofold anomaly in the respective dispersion curves . in order to explain this unusual behavior we performed density - functional theory calculations of the atomic and electronic structure , the vibrational properties , and the electronic susceptibility of those surfaces .
our work provides evidence for hydrogen adsorption induced fermi - surface nesting .
the respective nesting vectors are in excellent agreement with the has data and recent angle resolved photoemission experiments of the h - covered alloy system mo@xmath0re@xmath1(110 ) . also , we investigated the electron - phonon coupling and discovered that the rayleigh phonon frequency is lowered for those critical wave vectors compared to the clean surfaces .
moreover , the smaller indentation in the has spectra can be clearly identified as a kohn anomaly . based on our results for the susceptibility and the recently improved understanding of the he scattering mechanism
we argue that the larger anomalous dip is due to electron - hole excitations by the he scattering .
= 10000 .
And you have already written the first three sentences of the full article: much interest and many questions have been raised by the recent discovery of deep and extremely sharp indentations in the surface phonon spectra of h / mo(110 ) and h / w(110 ) at full hydrogen coverage @xcite ( see fig.[fanom ] ) .
those anomalies are seen at an incommensurate wavevector , @xmath2 , along the @xmath3 $ ] direction ( @xmath4 ) and additionally at the commensurate wavevector @xmath5 at the boundary of the surface brillouin zone ( sbz ) . out of the ordinary rayleigh mode
two simultaneous anomalies develop at those points . one ,.
Please generate the next two sentences of the article | @xmath6 , is extremely deep , and is only seen by helium atom scattering ( has ) .
the other , @xmath7 , is instead soft , and is observed by both has and high resolution electron energy loss spectroscopy ( hreels ) @xcite . |
8,192 | Suppose that you have an abstract for a scientific paper: we consider scattering and capture of circular cosmic strings by a schwarzschild black hole .
although being a priori a very simple axially symmetric two - body problem , it shows all the features of chaotic scattering . in particular , it contains a fractal set of unstable periodic solutions ; a so - called strange repellor .
we study the different types of trajectories and obtain the fractal dimension of the basin - boundary separating the space of initial conditions according to the different asymptotic outcomes .
we also consider the fractal dimension as a function of energy , and discuss the transition from order to chaos .
chaos in general relativity and cosmology is by now a well - established subject .
some studies , pioneered by the work of hawking @xcite and page @xcite , have been concerned with the behavior of solutions to the einstein equations themselves ; the most famous example now being the mixmaster universe ( see for instance @xcite , and references given therein ) . in other studies , the subject of interest has been the behavior of test - particle trajectories in black hole spacetimes ( see for instance @xcite ) . in the latter case ,
since point - particle motion is completely integrable in the generic kerr - newman background @xcite , it was necessary to consider quite complicated multi black hole spacetimes ( typically of the majumdar - papapetrou type @xcite ) to obtain chaotic point - particle dynamics . taking into account that these systems represent ( at least ) three - body problems , and comparing with newtonian dynamics , it was certainly no surprise that chaotic dynamics appeared .
( it should be mentioned , however , that in the two black hole case , chaos is really a relativistic effect @xcite . )
the main interest in these systems therefore was also to use and further develop coordinate - invariant descriptions and measures of chaotic behavior @xcite , suitable for general relativity where space and time are not absolute .
in the present paper , we....
And you have already written the first three sentences of the full article: we would like to thank v. p. frolov and d. n. page for stimulating discussions .
this research was supported by the natural sciences and engineering research council of canada and by the killam trust .
li hawking s w 1984 in _ relativity , groups and topology ii _ les houches session xl ( north holland , amsterdam ) page d n 1984 _ class ..
Please generate the next two sentences of the article | quantum grav . _ * 1 * 417 cornish n j and levin j j 1997 _ phys .
d _ * 55 * 7489 dettmann c p , frankel n e and cornish n j 1994 _ phys . |
8,193 | Suppose that you have an abstract for a scientific paper: we have carried out a multi - fractal analysis of the distribution of galaxies in the three northern slices of the las campanas redshift survey .
our method takes into account the selection effects and the complicated geometry of the survey . in this analysis
we have studied the scaling properties of the distribution of galaxies on length scales from @xmath0 to @xmath1 .
our main results are : ( 1 ) the distribution of galaxies exhibits a multi - fractal scaling behaviour over the scales @xmath2 to @xmath3 , and , ( 2 ) the distribution is homogeneous on the scales @xmath4 to @xmath1 .
we conclude that the universe is homogeneous at large scales and the transition to homogeneity occurs somewhere in the range @xmath3 to @xmath5 . .
And you have already written the first three sentences of the full article: many surveys have been carried out to chart the positions of galaxies in large regions of the universe around us , and many more surveys which go deeper into the universe are currently underway or are planned for the future .
these surveys give us detailed information about the distribution of matter in the universe , and identifying the salient features that characterize this distribution has been a very important problem in cosmology .
the statistical properties , the geometry and the topology are some of the features that have been used to characterize the distribution of galaxies , and a large variety of tools have been developed and used for this purpose ..
Please generate the next two sentences of the article | the correlation functions which characterize the statistical properties of the distributions have been widely applied to quantify galaxy clustering . of the various correlation functions ( 2-point , 3- point ,
etc ... ) the galaxy - galaxy two point correlation function @xmath6 is very well determined on small scales ( peebles 1993 and references therein ) and it has been found to have the form @xmath7 this power - law form of the two point correlation function suggests that the universe exhibits a scale invariant behaviour on small scales @xmath8 . the two point correlation function becomes steeper at larger scales @xmath9 . |
8,194 | Suppose that you have an abstract for a scientific paper: the u - cas is a spinning magnetized top that is levitated in a static magnetic field .
the field is produced by a permanent magnet base , positioned below the hovering top . in this paper
we derive upper and lower bounds for @xmath0the maximum hovering height of this top .
we show that the bounds are of the form @xmath1 where @xmath2 is a dimensionless number ranging from about @xmath3 to @xmath4 , depending on the constraints on the shape of the base and on stability considerations , and @xmath5 is a characteristic length , given by @xmath6 here , @xmath7 is the permeability of the vacuum , @xmath8 is the magnetic moment of the top , @xmath9 is the maximum magnetization of the base , @xmath10 is the mass of the top , and @xmath11 is the free - fall acceleration . for modern permanent magnets
we find that @xmath12[meter ] , thus limiting @xmath13 to about few meters . 0.25 in _ index terms _ * * u - cas , levitron , magnetic trap , magnetic levitation , hovering magnetic top . .
And you have already written the first three sentences of the full article: the u - cas is an ingenious device that hovers in mid - air while spinning .
it is marketed as a kit in japan under the trade name u - cas @xcite , and in the u.s.a . and
europe under the trade name levitron@xmath14 @xcite ..
Please generate the next two sentences of the article | the whole kit consists of three main parts : a magnetized top which weighs about @xmath15 gr , a thin ( lifting ) plastic plate and a magnetized square base plate ( base ) . to operate the top
one should set it spinning on the plastic plate that covers the base . |
8,195 | Suppose that you have an abstract for a scientific paper: we study a model for unimolecular reaction in a supported catalyst including reactant diffusion and desorption , using analytical methods and scaling concepts . for rapid reactions , enhancing surface diffusion or increasing particle size favors the flux of reactants to the catalyst particles , which increases the turnover frequency ( tof ) .
the reactant flux towards the support becomes dominant when the ratio of diffusion lengths in the catalyst and in the support exceeds a critical value .
a peak in the tof is obtained for temperature - dependent rates if desorption energy in the support ( @xmath0 ) exceeds those of diffusion ( @xmath1 ) and reaction ( @xmath2 ) .
significant dependence on particle size is observed when the gaps between those energies are small , with small particles giving higher tof .
slow reactions ( @xmath3 ) give tof monotonically increasing with temperature , with higher reactant losses in small particles .
the scaling concepts can be extended to interpret experimental data and results of more complex models . .
And you have already written the first three sentences of the full article: modeling heterogeneous catalytic processes is an essential tool for catalyst design and for the improvement of operating conditions @xcite .
hierarchical approaches have to be adopted due to the need of information on a wide range of length and time scales , from the electronic structure to the reactor design @xcite .
an important step of this approach is the microkinetic modeling , where microscopic processes such as reaction , diffusion , aggregation , and desorption are described by stochastic rules , providing information on the efficiency of the catalytic process in length scales ranging from a few nanometers to several micrometers ..
Please generate the next two sentences of the article | an important problem to be addressed with these methods is the effect of diffusion of reactants through the interface between the catalyst particle and the support .
several recent experimental papers illustrate these phenomena in catalyzed reactions @xcite as well as in related problems , such as gas adsorption @xcite , where the same materials may be used . |
8,196 | Suppose that you have an abstract for a scientific paper: the measurement of light characteristics at the single- and few photon level plays a key role in many quantum optics applications .
often photodetection is preceded with the transmission of quantum light over long distances in optical fibers with their low loss window near .
nonetheless , the detection of the photonic states at telecommunication wavelengths via avalanche photodetectors has long been facing severe restrictions .
only recently , demonstrations of the first free - running detector techniques in the telecommunication band have lifted the demand of synchronizing the signal with the detector .
moreover , moderate cooling is required to gain single - photon sensitivity with these detectors . here
we implement a liquid - nitrogen cooled negative - feedback avalanche diode ( nfad ) at telecommunication wavelengths and investigate the properties of this highly flexible , free - running single - photon sensitive detector .
our realization of cooling provides a large range of stable operating temperatures and has advantages over the relatively bulky commercial refrigerators that have been used before .
we determine the region of nfad working parameters most suitable for single - photon sensitive detection enabling a direct plug - in of our detector to a true photon counting task . .
And you have already written the first three sentences of the full article: the observation of a light quantum is a demanding task since the detector should be able to resolve this tiny amount of energy via the heat absorption or the photo - electric effect and in a noiseless fashion convert it to a measurable electric signal .
in addition to this , quantum features are extremely fragile and easily lost by any experimental imperfections prior to and at the detection .
nonetheless , in the past years , several photo - detector technologies have demonstrated the sensitivity to measure at the single - photon level @xcite . moreover , many quantum optics applications require photon counters with at least partial photon - number resolution @xcite . in such experiments ,.
Please generate the next two sentences of the article | superconducting detectors @xcite as well as visible light photon counters @xcite can be exploited with high efficiencies however , at the cost of having to cool to temperatures of a few kelvin . at room temperature
only a few options are available , for example photo - multiplier tubes @xcite that suffer from large losses or hybrid detectors @xcite that require specific reconstruction techniques . for photon counting tasks the most widely used detectors are avalanche photo diodes or shortly _ click detectors _ that are in geiger mode sensitive to single photons but unable to resolve various photon numbers @xcite . |
8,197 | Suppose that you have an abstract for a scientific paper: we extend the homogeneous modified chaplygin cosmologies to large - scale perturbations by formulating a zeldovich - like approximation .
we show that the model interpolates between an epoch with a soft equation of state and a de sitter phase , and that in the intermediate regime its matter content is simply the sum of dust and a cosmological constant .
we then study how the large - scale inhomogeneities evolve and compare the results with cold dark matter ( cdm ) , @xmath0cdm and generalized chaplygin scenarios .
interestingly , we find that like the latter , our models resemble @xmath0cdm . .
And you have already written the first three sentences of the full article: according to increasing astrophysical indicia , the evolution of the universe seems to be largely governed by dark energy with negative pressure together with pressureless cold dark matter ( see @xcite for the latest review ) in a two to one proportion . however , little is know about the origin of either component , which in the standard cosmological model would play very different roles : dark matter would be responsible for matter clustering , whereas dark energy @xcite would account for accelerated expansion . several candidates for dark energy haven proposed and confronted with observations : a purely cosmological constant , quintessence with a single field ( see @xcite for earliest papers ) or two coupled fields @xcite , k - essence scalar fields , and phantom energy @xcite .
interestingly , a bolder alternative presented recently suggests that an effective dark energy - like equation of state could be due to averaged quantum effects @xcite .
the lack of information regarding the provenance of dark matter and dark energy allows for speculation with the economical and aesthetic idea that a single component acted in fact as both dark matter and dark energy ..
Please generate the next two sentences of the article | the unification of those two components has risen a considerable theoretical interest , because on the one hand model building becomes considerable simpler , and on the other hand such unification implies the existence of an era during which the energy densities of dark matter and dark energy are strikingly similar .
one possible way to achieve that unification is through a particular k - essence fluid , the generalized chaplygin gas @xcite , with the exotic equation of state @xmath1 where constants @xmath2 and @xmath3 satisfy respectively @xmath4 and @xmath5 . using the energy conservation equation and the einstein equation @xmath6 one obtains the evolution @xmath7 where as usual @xmath8 is the scale factor , @xmath9 and @xmath10 is an integration constant . |
8,198 | Suppose that you have an abstract for a scientific paper: it is significant to apply load - balancing strategy to improve the performance and reliability of resource in data centers .
one of the challenging scheduling problems in cloud data centers is to take the allocation and migration of reconfigurable virtual machines ( vms ) as well as the integrated features of hosting physical machines ( pms ) into consideration . in the reservation model ,
the workload of data centers has fixed process interval characteristics . in general ,
load - balance scheduling is np - hard problem as proved in many open literatures .
traditionally , for offline load balance without migration , one of the best approaches is lpt ( longest process time first ) , which is well known to have approximation ratio 4/3 . with virtualization , reactive ( post ) migration of vms after
allocation is one popular way for load balance and traffic consolidation .
however , reactive migration has difficulty to reach predefined load balance objectives , and may cause interruption and instability of service and other associated costs . in view of this , we propose a new paradigm , called prepartition , it proactively sets process - time bound for each request on each pm and prepares in advance to migrate vms to achieve the predefined balance goal .
prepartition can reduce process time by preparing vm migration in advance and therefore reduce instability and achieve better load balance as desired .
trace - driven and synthetic simulation results show that prepartition for offline scheduling has 10@xmath0 - 20@xmath0 better performance than the well known load balancing algorithms with regard to average utilization , imbalance degree , makespan as well as capacity@xmath1makespan .
we also apply the prepartition to online ( prepartitionon ) load balance and compare it with existing online scheduling algorithms , in which prepartitionon can improve 8%-20% performance with regard to average cpu utilization , imbalance degree , makespan as well as capacity@xmath1makespan .
both....
And you have already written the first three sentences of the full article: in traditional data centers , applications are tied to specific physical servers that are often over - provisioned to deal with upper - bound workload .
such configuration makes data centers expensive to maintain with wasted energy and floor space , low resource utilization and significant management overhead . with virtualization technology ,
today s cloud data centers become more flexible , secure and provide better support for on - demand allocating . the definition and model defined by this paper.
Please generate the next two sentences of the article | are aimed to be general enough to be used by a variety of cloud providers and focus on the infrastructure as a service ( iaas ) .
cloud datacenters can be a distributed network in structure , containing many compute nodes ( such as servers ) , storage nodes , and network devices . |
8,199 | Suppose that you have an abstract for a scientific paper: we study the dust present in 56 galactic planetary nebulae ( pne ) through their iron depletion factors , their c / o abundance ratios ( in 51 objects ) , and the dust features that appear in their infrared spectra ( for 33 objects ) .
our sample objects have deep optical spectra of good quality , and most of them also have ultraviolet observations .
we use these observations to derive the iron abundances and the c / o abundance ratios in a homogeneous way for all the objects .
we compile detections of infrared dust features from the literature and we analyze the available _ spitzer_/irs spectra .
most of the pne have c / o ratios below one and show crystalline silicates in their infrared spectra .
the pne with silicates have c / o @xmath0 , with the exception of cn 1 - 5 .
most of the pne with dust features related to c - rich environments ( sic or the 30 @xmath1 m feature usually associated to mgs ) have c / o @xmath2 .
pahs are detected over the full range of c / o values , including 6 objects that also show silicates .
iron abundances are low in all the objects , implying that more than 90% of their iron atoms are deposited into dust grains .
the range of iron depletions in the sample covers about two orders of magnitude , and we find that the highest depletion factors are found in c - rich objects with sic or the 30 @xmath1 m feature in their infrared spectra , whereas some of the o - rich objects with silicates show the lowest depletion factors . .
And you have already written the first three sentences of the full article: planetary nebulae ( pne ) are suitable sites to study the evolution of dust grains since their progenitors , asymptotic giant branch ( agb ) stars , are among the most efficient sources of circumstellar dust in the galaxy @xcite .
these stars lose large amounts of material and create circumstellar envelopes with both low temperatures ( below 1500 k in the regions of dust formation ) and high densities ( @xmath3 10@xmath4 @xmath5 ) , where dust grains are efficiently formed . in @xcite , we studied iron depletions into dust grains in a sample of 33 galactic disk pne .
iron is an important contributor to the mass of dust grains @xcite , and its gaseous abundance can be used as a proxy for the amount of depletion of other elements ..
Please generate the next two sentences of the article | we found low iron gaseous abundances in all the objects , suggesting that more than 90% of their iron atoms are located in grains .
we also found that the range of iron depletions covers about two orders of magnitude , which may be a consequence of differences in the formation and evolution of the grains in the different nebulae . |
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