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11,900 |
Suppose that you have an abstract for a scientific paper: we briefly review , at a level appropriate for graduate students and non - specialists , the field of quasar absorption lines ( qals ) .
emphasis is on the intervening absorbers .
we present the anatomy of a quasar spectrum due to various classes of intervening absorption systems , and a brief historical review of each absorber class ( lyman - alpha forest and lyman limit systems , and metal - line and damped lyman - alpha absorbers ) .
we also provide several heuristic examples on how the physical properties of both the intergalactic medium and the gaseous environments associated with earlier epoch galaxies can be inferred from qals .
the evolution of these environments from z=4 are discussed . .
And you have already written the first three sentences of the full article: every parcel of gas along the line of sight to a distant quasar will selectively absorb certain wavelengths of continuum light of the quasar due to the presence of the various chemical elements in the gas . through the analysis of these quasar absorption lines we can study the spatial distributions , motions , chemical enrichment , and ionization histories of gaseous structures from redshift five until the present .
this includes the gas in galaxies of all morphological types as well as the diffuse gas in the intergalactic medium .
-0.15 in figure 1 illustrates many of the common features of a quasar spectrum . the relatively flat quasar continuum and broad emission features are produced by the quasar itself ( near the black hole and its accretion disk ) . in some cases , gas near the quasar central engine also produces `` intrinsic '' absorption lines , most notably , and relatively high ionization metal transitions such as , , and ..
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these intrinsic absorption lines can be broad [ thousands or even tens of thousands of in which case the quasar is called a broad absorption line ( bal ) qso ] , or narrow ( tens to hundreds of ) .
however , the vast majority of absorption lines in a typical quasar spectrum are `` intervening '' , produced by gas unrelated to the quasar that is located along the line of sight between the quasar and the earth .
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11,901 |
Suppose that you have an abstract for a scientific paper: hd molecules can be an important cooling agent of the primordial gas behind the shock waves originated through mergings of the dark matter haloes at epochs when first luminous objects were to form .
we study the necessary conditions for the hd cooling to switch on in the low temperature range @xmath0 k. we show that these conditions are fulfiled in merging haloes with the total ( dark matter and baryon ) mass in excess of @xmath1^{-2}\msun$ ] .
haloes with masses @xmath2 may be the sites of low - mass star formation .
[ firstpage ] early universe
cosmology : theory shock waves . .
And you have already written the first three sentences of the full article: cooling of primordial gas is determined by molecular hydrogen , which forms in an expanding universe after recombination ( lepp & shull 1983 , puy et al 1993 , palla , galli & silk 1995 , galli & palla 1998 , stancil , lepp & dalgarno 1998 ) . inside the first virialized dark matter
haloes the fraction of h@xmath3 can reach @xmath4 , which is able to cool gas to 200 k. at lower temperatures energy losses in roto - vibrational h@xmath3 lines become insufficient to cool gas further . on the other hand , owing to a low rotational energy and a large dipole moment hd molecules might be an efficient coolant at @xmath0 k. however , the abundance of hd is fairly sensitive to thermal history of the gas , so that the question of whether hd dominates radiative cooling at low temperatures or its contribution is negligible depends on physical conditions along the evolutionary path .
this circumstance is reflected in conradictory conclusions about the role of hd in thermodynamics of primordial gas : for instance , lepp & shull ( 1983 ) , bromm , coppi & larson ( 2002 ) point out that hd cooling can not dominate in primordial gas when the first objects form , while bougleux & galli ( 1997 ) , puy & signore ( 1997 , 1998 ) , and more recently uehara & inutsuka ( 2000 ) , flower ( 2002 ) , nakamura & umemura ( 2002 ) , flower & pineau des forets ( 2003 ) and machida et al ( 2005 ) find that hd molecules form in significant amount and can play a dominant role in thermal evolution of pregalactic gas ..
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transformation of h@xmath3 molecules into their isotop analog hd is energetically favoured because of higher binding energy of hd molecules . in equilibrium ( solomon & woolf 1973 , varshalovich & khersonskii 1976 ) = 2n(d)n(h)e^465/t , where factor 2 stems from the difference between the chemical constants of hd and h@xmath3 molecules : @xmath5 ( landau & lifshitz 1969 ) .
it is seen , that at @xmath6 k radiative hd cooling can enhance chemical fractionation of deuterated molecules progressively : a small decrease in temperature results in an increase of @xmath7 , what in turn increases radiative cooling in hd lines ( shchekinov , 1986 ) . in realistic conditions
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11,902 |
Suppose that you have an abstract for a scientific paper: the assumption of linear response of protein molecules to thermal noise or structural perturbations , such as ligand binding or detachment , is broadly used in the studies of protein dynamics .
conformational motions in proteins are traditionally analyzed in terms of normal modes and experimental data on thermal fluctuations in such macromolecules is also usually interpreted in terms of the excitation of normal modes .
we have chosen two important protein motors myosin v and kinesin kif1a and performed numerical investigations of their conformational relaxation properties within the coarse - grained elastic network approximation .
we have found that the linearity assumption is deficient for ligand - induced conformational motions and can even be violated for characteristic thermal fluctuations . the deficiency is particularly pronounced in kif1a where the normal mode description fails completely in describing functional mechanochemical motions .
these results indicate that important assumptions of the theory of protein dynamics may need to be reconsidered . neither a single normal mode , nor a superposition of such modes yield an approximation of strongly nonlinear dynamics . .
And you have already written the first three sentences of the full article: biological cells use a variety of molecular machines representing enzymes , ion channels or pumps , and motors .
motor proteins are nanometer - size devices generating forces and actively moving or rotating under the supply of chemical energy through atp hydrolysis .
they are crucial for many cell functions and promising for nanotechnology of the future ..
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although such motors represent single molecules , their operation cycles can not be in detail followed in simulations even on the best modern supercomputers and some approximations need to be employed .
it is often assumed that conformational dynamics of motor proteins is well described within a linear response approximation and corresponds to excitation of normal modes .
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11,903 |
Suppose that you have an abstract for a scientific paper: we point out a possible generation mechanism of non - gaussian bubbles in the sky due to bubble nucleation in the early universe .
we consider a curvaton scenario for inflation and assume that the curvaton field @xmath0 , whose energy density is subdominant during inflation but which is responsible for the curvature perturbation of the universe , is coupled to another field @xmath1 which undergoes false vacuum decay through quantum tunneling . for this model ,
we compute the skewness of the curvaton fluctuations due to its interaction with @xmath1 during tunneling , that is , on the background of an instanton solution that describes false vacuum decay .
we find that the resulting skewness of the curvaton can become large in the spacetime region inside the bubble .
we then compute the corresponding skewness in the statistical distribution of the cosmic microwave background ( cmb ) temperature fluctuations .
we find a non - vanishing skewness in a bubble - shaped region in the sky .
it can be large enough to be detected in the near future , and if detected it will bring us invaluable information about the physics in the early universe . .
And you have already written the first three sentences of the full article: inflation , a stage of accelerated expansion in the very early universe , is now widely accepted as part of the standard evolutionary scenario of the universe . on the other hand , many models of inflation have been proposed but we are still far from being able to narrow down the possible models sufficiently . among those many models of inflation ,
much attention has been paid recently to the ones based on string theory @xcite , which is considered to be a promising candidate for the ultimate unified theory . in particular , it is of great interest if the string theory landscape @xcite , in which there are many local minima , or false vacua , and the universe jumps from one minimum to another by quantum tunneling , can be observationally tested @xcite .
quantum tunneling of a scalar field with gravity is usually treated with the coleman - de luccia ( cdl ) instanton method @xcite , where the evolution of a scalar field is described with an o(4)-symmetric instanton , which is a solution of the euclidean equations of motion . motivated by the string landscape , inflation models with multi - scalar fields and/or with tunneling.
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are now keenly studied .
extension of the cdl instanton method to a multi - scalar field system is already discussed in @xcite . in those studies , however , many inflation models have been proposed , and now it is important to distinguish those models by observation .
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11,904 |
Suppose that you have an abstract for a scientific paper: exclusive and kinematically complete measurements of the double pionic fusion to @xmath0he have been performed in the energy region of the so - called abc effect , which denotes a pronounced low - mass enhancement in the @xmath1-invariant mass spectrum .
the experiments were carried out with the wasa detector setup at cosy .
similar to the observations in the basic @xmath2 reaction and in the @xmath3he@xmath4 reaction , the data reveal a correlation between the abc effect and a resonance - like energy dependence in the total cross section .
differential cross sections are well described by the hypothesis of @xmath5 resonance formation during the reaction process in addition to the conventional @xmath6-channel @xmath7 mechanism .
the deduced @xmath5 resonance width can be understood from collision broadening due to fermi motion of the nucleons in initial and final nuclei . .
And you have already written the first three sentences of the full article: historically the so - called abc effect , which denotes an intriguing low - mass enhancement in the @xmath1 invariant mass spectrum , is known from inclusive measurements of two - pion production in nuclear fusion reactions to the few - body systems @xmath8 , @xmath0he and @xmath9he .
it has been named after the initials of abashian , booth and crowe , who were the first to observe this effect in 1960 by studying the inclusive @xmath10he x reaction @xcite .
its explanation has been a puzzle since then . in subsequent bubble - chamber @xcite and single - arm magnetic spectrometer measurements @xcite this enhancement.
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was observed also in double - pionic fusion reactions leading to @xmath8 , @xmath0he and @xmath9he , if an isoscalar pion pair was produced .
however , such an enhancement was not observed in fusion reactions leading to deuteron and triton , if an isovector pion pair was produced .
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11,905 |
Suppose that you have an abstract for a scientific paper: the measured spectral energy distribution and variability time scale are used to determine the radiation and magnetic - field energy densities in the relativistic plasma that forms the gamma - ray emitting jet in the blazar 3c 279 . assuming that protons are accelerated as efficiently as electrons to a maximum energy determined by the size and magnetic field of the emitting region , we calculate the emissivity of neutrinos produced by protons that interact with the external radiation field intercepted by the jet .
the external radiation field provides the most important target photons for photomeson production of high - energy neutrinos in flat spectrum radio quasars ( fsrqs ) . because of photomeson interactions with this field , km@xmath0
neutrino telescopes are predicted to detect @xmath1 - 1 neutrinos per year from blazars such as 3c 279 .
bl lac objects are weaker neutrino sources if , as widely thought , their @xmath2-ray emission is due to compton - scattered synchrotron ( ssc ) radiation . .
And you have already written the first three sentences of the full article: blazars are among the most powerful accelerators of relativistic particles in nature , as shown by egret observations of 100 mev - gev emission from over 60 fsrqs and bl lac objects .
consequently , blazars represent a potential source of high - energy neutrinos ( see gaisser et al .
1995 and halzen 2001 for reviews ) ..
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the bright , highly variable @xmath2 radiation from blazars argues for the existence of emission regions with high photon energy densities and intense nonthermal particle populations , which are needed for efficient photomeson production ( e.g. , mannheim and biermann 1992 ; mannheim et al.2001 ) .
previous papers have considered internal synchrotron photons as targets for high - energy proton interactions ( e.g. , mannheim 1993 ) .
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11,906 |
Suppose that you have an abstract for a scientific paper: the first - year wilkinson microwave anisotropy probe data suggest a high optical depth for thomson scattering of 0.17 @xmath0 0.04 , implying that the universe was reionized at an early epoch , @xmath1 .
such early reionization is likely to be caused by uv photons from first stars , but it appears that the observed high optical depth can be reconciled within the standard structure formation model only if star - formation in the early universe was extremely efficient . with normal star - formation efficiencies , cosmological models with non - gaussian density fluctuations may circumvent this conflict as high density peaks collapse at an earlier epoch than in models with gaussian fluctuations .
we study cosmic reionization in non - gaussian models and explore to what extent , within available constraints , non - gaussianities affect the reionization history . for mild non - gaussian fluctuations at redshifts of 30 to 50 ,
the increase in optical depth remains at a level of a few percent and appears unlikely to aid significantly in explaining the measured high optical depth . on the other hand , within available observational constraints , increasing the non - gaussian nature of density fluctuations can easily reproduce the optical depth and may remain viable in underlying models of non - gaussianity with a scale - dependence . .
And you have already written the first three sentences of the full article: the excess large scale polarization signal in the wilkinson microwave anisotropy probe ( wmap ) data has allowed the first measurement of the optical depth to re - scattering by electrons with a value of @xmath2 ( kogut et al . 2003 ) .
if interpreted as a sharp transition to a reionized universe from a neutral one , the redshift at which this transition happens is @xmath3 @xcite .
theoretical studies based on cold dark matter ( cdm ) models suggest that such a high reionization redshift beyond what was previously suggested with gunn - peterson troughs in @xmath4 quasars from the sloan survey ( e.g. , fan et al ..
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2002 ) generally requires significant star - formation early on , at @xmath5 ( cen 2003 ; haiman & holder 2003 ; sokasian et al .
2003 ; yoshida et al .
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11,907 |
Suppose that you have an abstract for a scientific paper: the family of binary compounds including taas , tap , nbas , and nbp was recently discovered as the first realization of weyl semimetals . in order to develop a comprehensive description of the charge carriers in these weyl semimetals
, we performed a detailed and systematic electronic band structure calculations which reveal the nature of fermi surfaces and their complex interconnectivity in taas , tap , nbas , and nbp .
our work report the first comparative and comprehensive study of fermi surface topology and band structure details of all known members of the weyl semimetal family and provide the necessary building blocks for advancing our understanding of their unique topologically protected low - energy weyl fermion physics . .
And you have already written the first three sentences of the full article: the discovery of dirac fermions as low - energy quasi - particle excitations in graphene and on the surfaces of topological insulators has drawn significant attention in both fundamental physics research and device applications @xcite .
since these dirac - like fermions propagate as massless relativistic particles they behave differently from the conventional charge carriers in metals , semiconductors , and insulators . recently
, a new form of massless fermions with lifted degeneracy at the nodal point , from four - fold to two - fold , has been proposed to exist in condensed matter systems through a time reserval or inversion symmetry breaking mechanism ..
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this symmetry breaking operation modifies the quasi - particle s dispersion relation from a dirac to a weyl equation.@xcite many theoretical proposals exist for realizing weyl semimetals that possess interesting physical properties , such as discontinuous fermi arcs and negative magnetoresistance due to the chiral anomaly.@xcite a weyl node with definite chirality is associated with the berry curvature and may be thought of as realizations of magnetic monopoles in momentum space.@xcite recent theoretical works have proposed the realization of the weyl semimetal state in the inversion symmetry breaking taas family.@xcite shortly after the prediction , the first weyl semimetal was experimentally discovered in taas @xcite .
the electronic weyl semimetal state in taas was experimentally observed through photoemission spectroscopy@xcite .
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11,908 |
Suppose that you have an abstract for a scientific paper: given a random word of size @xmath0 whose letters are drawn independently from an ordered alphabet of size @xmath1 , the fluctuations of the shape of the random rsk young tableaux are investigated , when @xmath0 and @xmath1 converge together to infinity . if @xmath1 does not grow too fast and if the draws are uniform , then the limiting shape is the same as the limiting spectrum of the gue . in the non - uniform case , a control of both highest probabilities will ensure the convergence of the first row of the tableau toward the tracy
widom distribution . .
And you have already written the first three sentences of the full article: let @xmath2 be an ordered alphabet of size @xmath1 and let a word be made of the random letters @xmath3 ( independently ) drawn from @xmath4 . recall that the robinson schensted
knuth ( rsk ) correspondence associates to a ( random ) word a pair of ( random ) young tableaux of the same shape , having at most @xmath1 rows ( see , e.g. , @xcite or @xcite ) .
it is then well known that the length , @xmath5 , of the top row of these tableaux coincides with the length of the longest ( weakly ) increasing subsequence of @xmath6 ..
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the behavior of @xmath5 when @xmath0 and/or @xmath1 go to @xmath7 and its connections to various areas of mathematics ( e.g. , random matrices , queueing theory , percolation theory ) have been investigated in numerous papers ( @xcite , @xmath8 ) .
for instance , appropriately renormalized and for uniform draws , @xmath5 converges in law , as @xmath0 goes to infinity and @xmath1 is fixed , to the largest eigenvalue of an @xmath9 matrix from the traceless gaussian unitary ensemble ( gue ) .
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11,909 |
Suppose that you have an abstract for a scientific paper: a relativistic non - local model for the inclusive photoproduction of @xmath0 mesons from complex nuclei is introduced .
the model is based on the dominance of the s@xmath1(1535 ) resonance .
we compare the results of our calculations with the available data on inclusive cross sections for the nuclei c , al and cu . assuming the resonance propagates freely in the nuclear medium , we find that the calculated angular distribution and energy dependence of the cross sections reproduce the data in a reasonable fashion .
the present non - local model allows the inclusion of density dependent mass and width in the calculations . including these in the calculations
reveals that the presently available data do not show clear preference for the inclusion of such modifications of the properties of the s@xmath1(1535 ) in the nuclear medium .
pacs number(s ) 25.20.lj , 24.10.jv , 14.20.gk , 13.60.le [ intro ] .
And you have already written the first three sentences of the full article: the question of possible modifications of hadron properties in the nuclear medium has attracted considerable interest in recent years .
this interest stems from the hope that studies of these effects can clarify the interplay of the competing degrees of freedom in the nucleus .
in particular it may be possible to learn about explicit quark degrees of freedom in the nucleus through such studies ..
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there have been several theoretical as well as experimental investigations of these effects , and evidence is gathering that indeed such modifications do take place .
several studies have been carried out for the modifications of meson properties in heavy ion and other collisions @xcite .
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11,910 |
Suppose that you have an abstract for a scientific paper: long - term monitoring of low mass x - ray binaries ( lmxbs ) by the all sky monitor on board the rossi x - ray timing explorer now covers @xmath013 yrs and shows that certain lmxb types display very long - term ( @xmath0 several to tens of years ) quasi - periodic modulations .
these timescales are much longer than any `` super - orbital '' periods reported hitherto and likely have a different origin .
we suggest here that they are due to long - term variations in the mass - transfer rate from the donor , which are a consequence of solar - like magnetic cycles that lead to @xmath1 changes ( as proposed by richman , applegate & patterson 1994 for similar long - term variations in cvs ) .
atoll sources display much larger amplitude modulations than z sources over these timescales , presumably because z sources are eddington limited and hence unable to respond as readily as atoll sources to fluctuations in the mass - transfer rate from the donor .
[ firstpage ] .
And you have already written the first three sentences of the full article: low mass x - ray binaries ( lmxbs ) contain a neutron star ( ns ) or black hole ( bh ) primary onto which material is transferred from a low - mass ( @xmath2 ) late - type , essentially normal main sequence ( ms ) star ( spectral type @xmath0a - m ) , with longer period systems containing a sub - giant .
there are @xmath0190 luminous ( @xmath3 ergs@xmath4 ) lmxbs known in our galaxy ( liu , van paradijs & van den heuvel 2007 ) .
cataclysmic variables ( cvs ) are very similar , but have white dwarf ( wd ) primaries at a @xmath5 factor reduction in luminosity and have orbital periods that range from hours to @xmath6 d. while the flux from lmxbs is predominantly in x - rays which originate from the inner accretion disc and the ns surface ( where applicable ) , the flux from cvs is predominantly in the optical and originates from the entire accretion disc , the hot spot(s ) on the wd surface and the disc - mass - transfer stream impact region ..
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( for details see e.g. frank , king & raine 1992 ) . long - term , non - orbital , quasi - periodic variations on timescales of @xmath0tens - hundreds of days in lmxbs were discovered early in x - ray astronomy ( see charles et al .
2008 for a recent review ) .
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11,911 |
Suppose that you have an abstract for a scientific paper: in this work we revisit the topic of two - dimensional bose - einstein condensates under the influence of time - dependent magnetic confinement and time - dependent scattering length .
a moment approach reduces the examination of moments of the wavefunction ( in particular , of its width ) to an ermakov - pinney ( ep ) ordinary differential equation ( ode ) .
we use the well - known structure of the solutions of this nonlinear ode to `` engineer '' trapping and interatomic interaction conditions that lead to condensates dispersing , breathing or even collapsing .
the advantage of the approach is that it is fully tractable analytically , in excellent agreement with our numerical observations . as an aside
, we also discuss how similar time - dependent ep equations may arise in the description of anisotropic scalar field cosmologies . .
And you have already written the first three sentences of the full article: the recent progress in experimental and theoretical studies of bose - einstein condensates ( becs ) of dilute atomic gases @xcite has been tremendous after their experimental realization @xcite .
this has also led to an explosion of interest in the theme of nonlinear matter - waves such as dark @xcite , bright @xcite and gap @xcite solitons .
two - dimensional ( 2d ) nonlinear excitations of becs , such as vortices @xcite and vortex lattices @xcite , were also realized experimentally , while a multitude of other coherent nonlinear structures were also theoretically predicted ; these include , e.g. , faraday waves @xcite , ring dark solitons and vortex necklaces @xcite , stable solitons and localized vortices in attractive becs trapped in periodic potentials @xcite , matter - wave gap vortices @xcite , 2d bright solitons in dipolar becs @xcite , and so on . from the theoretical standpoint ,.
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the dynamics of such higher - dimensional structures is , generally , difficult to be treated analytically , especially so in time - dependent settings .
this , in turn , raises important questions concerning their `` controllability '' , which would be of particular relevance regarding potential applications .
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11,912 |
Suppose that you have an abstract for a scientific paper: higgs - boson production at the photon collider at tesla is studied for masses from 180 to 350 gev , using realistic luminosity spectra and detector simulation .
parity of the sm higgs - boson can be verified from the measurement of the interference effects in the @xmath0 decay channel and of the angular correlations in the decays of @xmath0 and @xmath1 pairs .
sm - like two higgs doublet model ( 2hdm ii ) and model with the generic higgs couplings are considered . .
And you have already written the first three sentences of the full article: a photon collider has been proposed as a natural extension of the linear collider project tesla @xcite .
the physics potential of a photon collider is very rich and complementary to the physics program of the and hadron - hadron colliders .
it is an ideal place to study the mechanism of the electroweak symmetry breaking ( ewsb ) and the properties of the higgs - boson . in paper.
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@xcite we performed realistic simulation of sm higgs - boson production at the photon collider for @xmath0 and @xmath2 decay channels , for higgs - boson masses above 150 gev . due to an interference with a large standard model background ,
the process @xmath3 turns out to be sensitive not only to the higgs - boson partial width to , , but also to the phase of the @xmath4 coupling , .
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11,913 |
Suppose that you have an abstract for a scientific paper: we show that inconclusive photon subtraction ( ips ) on twin - beam produces non - gaussian states that violate bell s inequality in the phase - space .
the violation is larger than for the twin - beam itself irrespective of the ips quantum efficiency .
the explicit expression of ips map is given both for the density matrix and the wigner function representations . .
And you have already written the first three sentences of the full article: the twin - beam state ( twb ) of two modes of radiation can be expressed in the photon number basis as @xmath0 where @xmath1 , @xmath2 being the twb squeezing parameter .
twb is described by a gaussian wigner function @xmath3 with @xmath4 and @xmath5 .
since ( [ twb : wig ] ) is positive - definite , twb are not suitable to test nonlocality through homodyne detection ..
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indeed , the wigner function itself provides an explicit hidden variable model for homodyne measurements @xcite . on the other hand ,
it has been shown @xcite that twb exhibits a nonlocal character for parity measurements .
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11,914 |
Suppose that you have an abstract for a scientific paper: in order to settle the problem of the post constraint " in material media , we consider the propagation of a plane electromagnetic wave in a medium with a piecewise constant axion field .
although a constant axion field does not affect the wave propagation in a homogeneous medium , we show that the reflection and transmission of a wave at an interface between the two media is sensitive to the difference of the axion values .
this observation can be used to determine experimentally the axion piece in matter despite the fact that a constant axion value does not contribute to the maxwell equations .
= 10000 .
And you have already written the first three sentences of the full article: recently , we discussed local and linear media in classical electrodynamics @xcite . in particular , we investigated possible magnetoelectric effects , which are related to the crossterms between the magnetic ( electric ) field strength and the electric ( magnetic ) excitation . using the premetric formalism of electrodynamics ,
see @xcite , the most general local and linear constitutive relation can be written as @xmath0 here @xmath1 and @xmath2 are the electric and magnetic excitations , respectively , and @xmath3 and @xmath4 the electric and the magnetic field strengths .
the kronecker symbol is denoted by @xmath5 , the totally antisymmetric levi - civita symbol by @xmath6 and @xmath7 , respectively ..
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we have 36 constitutive functions or moduli : the permittivity matrix @xmath8 ( 6 independent components ) , the impermeability matrix @xmath9 ( 6 components ) , the tracefree principal magnetoelectric matrix @xmath10 ( 8 components ) , the 15 skewon pieces @xmath11 , and , eventually , 1 axion piece @xmath12 . such a local and linear medium with 36 moduli
called sometimes bi - anisotropic has been considered , amongst others , by lindell , sihvola , tretyakov , and collaborators @xcite . in conventional materials
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11,915 |
Suppose that you have an abstract for a scientific paper: the problem of elementarity of electric charge is investigated .
it is known that possible proton decay is caused by @xmath0 and @xmath1 bosons which are characteristic in guts .
the charge structure of guts is , however , not simple , and the five types of charge units appear .
we investigate the problem of elementarity in taking into account of the simplest model of the charge structure known as the rishon model , where the charge units are known as 1/3 ( @xmath2 ) and 0 ( @xmath3 ) . in order to approach to sub - structure together with the problem of simplicity of charge structure ,
possible rearrangements of rishons are investigated on the basis of color and hypercolor confinement condition .
further , possible existence of the simplest electroweak sub - structure is discussed .
our model predicts possible proton decay mode , in which @xmath0 and @xmath1 bosons are not concerned . .
And you have already written the first three sentences of the full article: in the progress of high - energy physics , so - called energy frontier have reached to a few tev region , where discoveries of new phenomena are expected .
in such situation , it is well known that the five unites of electric charge , q = 0 , 1/3 , 2/3 , 1 , 4/3 appear in guts@xcite , where the 4/3 charge is carried by @xmath0 gauge boson , which is considered to be the particle responsible for proton decay .
thus , so far as the charge units are concerned , it seems that guts are too complicated to be the final theory of elementary particles ..
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especially , in any gauge model such as guts , the @xmath4 symmetry concerning to the conservation of electric charge is absolutely maintained in the final stage of steps of symmetry breaking .
furthermore , it is known that the electric charge remains and is conserved even in a critical condition such as the gravitational collapse of matter , where almost all quantum numbers looses their meanings@xcite .
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11,916 |
Suppose that you have an abstract for a scientific paper: symmetry is an important problem in many combinatorial problems .
one way of dealing with symmetry is to add constraints that eliminate symmetric solutions .
we survey recent results in this area , focusing especially on two common and useful cases : symmetry breaking constraints for row and column symmetry , and symmetry breaking constraints for eliminating value symmetry . .
And you have already written the first three sentences of the full article: symmetry occurs in many constraint satisfaction and optimisation problems @xcite . for example , suppose we have a proper coloring of a graph , and we permute the colors then we will obtain another symmetric coloring .
symmetries are problematic as they increase the size of the search space .
we will waste time visiting symmetric solutions ..
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worse still , we will waste even more time visiting the ( many failing ) parts of the search tree which are symmetric to already visited states . a common and effective method to deal with symmetry is to add constraints which eliminate some , but not all symmetric solutions ( e.g. @xcite ) . in this paper , we survey recent results on symmetry breaking constraints .
we hope that this survey is of wider interest as many of the results are likely to translate to other domains like planning , model checking and heuristic search .
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11,917 |
Suppose that you have an abstract for a scientific paper: we present interferometric observations of co @xmath0 emission in the central regions of the edge - on galaxy ngc 4631 , known for its extended gaseous halo and its tidal interactions .
previous single - dish observations revealed that almost all of the co emission arises from a central ring or bar - like structure of length @xmath1 4 kpc .
we confirm this structure at higher resolution , and find that it is bent at the center , reflecting the overall bend in this galaxy apparent from optical images .
the kinematic evidence favors a rigidly rotating ring over a bar .
the gaseous halo emission in several tracers is concentrated above and below this molecular structure . to the north of an emission peak at the eastern end of
the structure is an extraplanar feature showing filamentary and shell - like properties which we interpret as an energetic molecular outflow .
the energies involved are difficult to estimate , but are probably of order 10@xmath2 ergs or more .
the co concentration in the disk below this structure coincides with a bright hii region complex , a peak of radio emission , and the brightest x - ray feature in the inner disk of the galaxy seen in a rosat hri map , all suggesting intense star formation .
a filament of radio continuum emission may also have a footprint in this region of the disk .
the origin of the outflow is unclear . .
And you have already written the first three sentences of the full article: ngc 4631 is one of the best examples of a nearby edge - on galaxy with a star formation driven outflow resulting in a bright and extended gaseous halo .
this is seen in many tracers : h@xmath3 ( rand , kulkarni , & hester 1992 ; hoopes , walterbos , & rand 1999 ) , radio continuum ( e.g. ekers & sancisi 1977 ; hummel & dettmar 1990 ; golla & hummel 1994 ) , and x - rays ( wang et al . 1995 ; vogler & pietsch 1996 ) .
this galaxy is undergoing interactions with two companions , ngc 4627 and ngc 4656 , and shows a complex pattern of tidal features seen in hi ( weliachew , sancisi , & gulin 1978 ; rand 1994 ) , and more recently to a lesser extent in cold dust ( neininger & dumke 1999 ) ..
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it also shows two large and highly energetic hi supershells ( rand & van der hulst 1993 ) , the origin of which is not clear ( rand & stone 1996 ; loeb & perna 1998 ) .
the disturbances to the disk resulting from the interactions may have caused the rather high level of star formation [ @xmath4 ergs s@xmath5 , uncorrected for internal extinction ( rand , kulkarni & hester 1992 ) ] .
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11,918 |
Suppose that you have an abstract for a scientific paper: we present an analysis of the effects of environment on the photometric properties of galaxies in the core of the shapley supercluster at @xmath0 , one of the most massive structures in the local universe .
the shapley optical survey ( sos ) comprises archive wfi optical imaging of a 2.0deg@xmath1 region containing the rich clusters a3556 , a3558 and a3562 which demonstrate a highly complex dynamical situation including ongoing cluster mergers .
the colour - magnitude relation has an intrinsic dispersion of 0.045mag and is mag redder in the highest - density regions , indicative of the red sequence galaxy population being 500myr older in the cluster cores than towards the virial radius .
the @xmath2 colours of galaxies are dependent on their environment , whereas their luminosities are independent of the local density , except for the very brightest galaxies .
the global colours of faint galaxies change from the cluster cores where of galaxies lie along the cluster red sequence to the virial radius , where the fraction has dropped to just this suggests that processes related to the supercluster environment are responsible for transforming faint galaxies , rather than galaxy merging , which should be infrequent in any of the regions studied here .
the largest concentrations of faint blue galaxies are found _ between _ the clusters , coincident with regions containing high fractions of galaxies with radio emission indicating starbursts .
their location suggests star - formation triggered by cluster mergers , in particular the merger of a3562 and the poor cluster sc1329 - 313 , although they may also represent recent arrivals in the supercluster core complex .
the effect of the a3562-sc1329 - 313 merger is also apparent as a displacement in the spatial distribution of the faint galaxy population from both the centres of x - ray emission and the brightest cluster galaxies for both systems .
the cores of each of the clusters / groups are marked by regions that have the lowest blue galaxy fractions....
And you have already written the first three sentences of the full article: the cluster galaxy population has evolved rapidly over the last 4gyr ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
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* ; * ? ? ?
* ; * ? ? ?
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11,919 |
Suppose that you have an abstract for a scientific paper: this project work report provides a full solution of simplified navier stokes equations for the incompressible couette problem .
the well known analytical solution to the problem of incompressible couette is compared with a numerical solution . in that paper
, i will provide a full solution with simple c code instead of matlab or fortran codes , which are known . for discrete problem formulation ,
implicit crank - nicolson method was used .
finally , the system of equation ( tridiagonal ) is solved with both thomas and simple gauss method .
results of both methods are compared . .
And you have already written the first three sentences of the full article: main problem is shown in figure ( [ schema1 ] ) .
there is viscous flow between two parallel plates .
upper plate is moving in x direction with constans velocity @xmath0 ..
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lower one is not moving @xmath1 .
we are looking for a solution to describe velocity vector field in the model ( between two plates ) .
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11,920 |
Suppose that you have an abstract for a scientific paper: quasiparticle properties in the superconducting state are masked by the superfluid and are not directly accessible to infrared spectroscopy .
we show how one can use a kramers kronig transformation to separate the quasiparticle from superfluid response and extract intrinsic quasiparticle properties in the superconducting state .
we also address the issue of a narrow quasiparticle peak observed in microwave measurements , and demonstrate how it can be combined with infrared measurements to obtain unified picture of electrodynamic properties of cuprate superconductors . .
And you have already written the first three sentences of the full article: infrared spectroscopy has in the past several decades become one of the premier experimental tools in condensed matter physics @xcite .
thanks to its versatility , it has been successfully applied to essentially all types of condensed matter systems , such as superconductors , topological insulators , graphene , etc . in particular , in high - t@xmath0 cuprate superconductors , infrared based techniques have been extensively used to probe a variety of unusual and yet unresolved issues concerning their unconventional pairing state @xcite . in recent years
a number of attempts has been made to elucidate the properties of quasiparticles and their relaxation in the cuprates @xcite ..
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these attempts are based on the so - called extended - drude model , which allows both the quasiparticle scattering rate and their effective mass to acquire frequency dependence .
these two quantities can be straightforwardly obtained from the complex optical conductivity @xmath1 as : @xmath2= \frac{\omega_{p}^{2 } } { 4 \pi } \frac{\sigma_1(\omega ) } { \sigma_1 ^ 2(\omega)+\sigma_2 ^ 2(\omega ) } % \label{eq : tau}\ ] ] @xmath3 \frac{1}{\omega } = \frac{\omega_{p}^{2}}{4 \pi } \frac{\sigma_2(\omega ) } { \sigma_1 ^ 2(\omega)+\sigma_2 ^ 2(\omega)}\frac{1}{\omega } \label{eq : mass}\ ] ] where the plasma frequency @xmath4 is usually obtained from the integration of @xmath5 up to the frequency of the onset of interband absorption : @xmath6 equations [ eq : tau ] and [ eq : mass ] are the basis of a so - called _ one - component _ approach @xcite for the interpretation of optical properties , which assumes the existence of a single type of charge carriers in the system .
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11,921 |
Suppose that you have an abstract for a scientific paper: planetary nebulae ( pne ) derive from the evolution of @xmath018 m@xmath1 mass stars , corresponding to a wide range of progenitor ages , thus are essential probes of the chemical evolution of galaxies , and indispensable to constrain the results from chemical models .
we use an extended and homogeneous data set of galactic pne to study the metallicity gradients and the galactic structure and evolution .
the most up - to - date abundances , distances ( calibrated with magellanic cloud pne ) , and other parameters have been employed , together with a novel homogeneous morphological classification , to characterize the different pn populations . we confirm that morphological classes have a strong correlation with pn peimbert s type , and also with their distribution on the galactic landscape .
we studied the @xmath2-element distribution within the galactic disk , and found that the best selected disk population ( i.e. , excluding bulge and halo component ) , together with the most reliable pn distance scale yields to a radial oxygen gradient of @xmath3log(o / h)/@xmath3r@[email protected] dex kpc@xmath6 for the whole disk sample , and of @xmath3log(o / h)/@xmath3r@xmath4= [email protected] , [email protected] , and [email protected] dex kpc@xmath6 respectively for type i , ii , and iii pne , i.e. , for high- , intermediate- , and low - mass progenitors .
neon gradients for the same pn types confirm the trend .
accurate statistical analysis show moderately high uncertainties in the slopes , but also confirm the trend of steeper gradient for pne with more massive progenitors , indicating a possible steepening with time of the galactic disk metallicity gradient for what the @xmath2-elements are concerned .
we found that the metallicity gradients are almost independent on the distance scale model used , as long as these scales are equally well calibrated with the magellanic clouds .
the pn metallicity gradients presented here are consistent with the local metallicity distribution ;....
And you have already written the first three sentences of the full article: it has been assumed over the years that the building of galactic disks is driven inside - out by the continuous accretion of in - falling gas ( larson 1976 ) .
evidences for the validity of the inside - out paradigm are still slim however , and are actively searched for . inspection of detailed cdm simulations have shown that this picture may not be universal , and may vary from one galaxy to the other , to the point that some simulations show examples where galaxies can build their disk outside - in , at least partly ( see e.g sommer - larsen et al .
2003 , roberston et al ..
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2004 ) . in this
respect , radial variations of properties of the galactic disk may provide important observational constraints , but this has been hampered by the lack of tracers for which distance can be measured with the relevant accuracy , explaining why the magnitude of abundance gradients in the disk is still actively debated .
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11,922 |
Suppose that you have an abstract for a scientific paper: stellar population synthesis ( sps ) provides the link between the stellar and dust content of galaxies and their observed spectral energy distributions . in the present work
we perform a comprehensive calibration of our own flexible sps ( fsps ) model against a suite of data .
these data include ultraviolet , optical , and near ir photometry , surface brightness fluctuations , and integrated spectra of star clusters in the magellanic clouds ( mcs ) , m87 , m31 , and the milky way ( mw ) , and photometry and spectral indices of both quiescent and post starburst galaxies at @xmath0 .
several public sps models are intercompared , including the models of bruzual & charlot ( bc03 ) , maraston ( m05 ) and fsps .
the relative strengths and weaknesses of these models are evaluated , with the following conclusions : 1 ) the fsps and bc03 models compare favorably with mc data at all ages , whereas m05 colors are too red and the age dependence is incorrect ; 2 ) all models yield similar optical and near ir colors for old metal
poor systems , and yet they all provide poor fits to the integrated @xmath1 and @xmath2 colors of both mw and m31 star clusters ; 3 ) fsps is able to fit all of the ultraviolet data because both the post agb and horizontal branch evolutionary phases are handled flexibly , while the bc03 and m05 models fail in the far uv , and
both far and near uv , respectively ; 4 ) all models predict @xmath3 colors too red , d@xmath4 strengths too strong and h@xmath5 strengths too weak compared to massive red sequence galaxies , under the assumption that such galaxies are composed solely of old metal rich stars ; 5 ) fsps and , to a lesser extent , bc03 can reproduce the optical and near
ir colors of post starburst galaxies , while m05 can not .
reasons for these discrepancies are explored .
the failure at predicting the @xmath3 colors , d@xmath4 , and h@xmath5 strengths can be explained by some combination of a minority population of metal poor stars , young stars , blue....
And you have already written the first three sentences of the full article: the spectral energy distribution ( sed ) of a galaxy contains a wealth of information regarding its star formation history , dust content , and chemical abundance pattern .
these properties provide essential clues to the physical processes governing the formation and evolution of galaxies from high redshift to the present .
it is therefore highly desirable to have a robust method for extracting the physical properties of galaxies from their seds ..
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the process of translating observed seds into physical properties is , unfortunately , very challenging because it requires 1 ) an accurate understanding of all phases of stellar evolution , 2 ) well calibrated stellar spectral libraries for converting stellar evolution calculations into measurable fluxes , 3 ) an initial mass function ( imf ) , specifying the weight given to each stellar mass , 4 ) detailed knowledge of the star dust geometry in conjunction with an appropriate extinction curve ; i.e. , knowledge of the physical conditions of the interstellar medium ( ism ) .
each of these requirements depend on chemical composition , further compounding the problem . combining these ingredients in order to predict the spectrum of a galaxy
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11,923 |
Suppose that you have an abstract for a scientific paper: observations from the rossi x - ray timing explorer have shown the existence of high frequency quasi - periodic oscillations ( hfqpos ) in the x - ray flux from accreting black hole binary systems . in at least two systems ,
these hfqpos come in pairs with a 2:3 frequency commensurability .
we propose a simple `` hot spot '' model to explain the position and amplitude of the hfqpo peaks .
using the exact geodesic equations for the kerr metric , we calculate the trajectories of massive test particles , which are treated as isotropic , monochromatic emitters in their rest frames .
photons are traced from the accretion disk to a distant observer to produce time- and frequency - dependent images of the orbiting hot spot and background disk .
the power spectrum of the x - ray light curve consists of multiple peaks at integral combinations of the black hole coordinate frequencies .
in particular , if the radial frequency is one - third of the azimuthal frequency ( as is the case near the inner - most stable circular orbit ) , beat frequencies appear in the power spectrum at two - thirds and four - thirds of the fundamental azimuthal orbital frequency , in agreement with observations .
we also model the effects of shearing the hot spot in the disk , producing an arc of emission that also follows a geodesic orbit , as well as the effects of non - planar orbits that experience lens - thirring precession around the black hole axis . by varying the arc length
, we are able to explain the different qpo features observed in `` type a '' and `` type b '' x - ray outbursts from xte j1550 - 564 . in the context of this model ,
the observed power spectra allow us to infer values for the black hole mass and angular momentum , and also constrain the parameters of the model , such as the hot spot size and luminosity . .
And you have already written the first three sentences of the full article: in the past decade , observations of x - ray emission from accreting neutron stars and black holes have introduced new possibilities for astrophysical tests of fundamental physics .
recent discoveries made by satellites such as asca , rxte , bepposax , chandra , and xmm - newton provide direct evidence for strong - field gravitational effects in compact binary systems and active galactic nuclei ( agn ) .
these results include doppler - broadened iron k@xmath0 fluorescent emission from microquasars @xcite and millisecond variability of the x - ray flux from black holes in low - mass x - ray binaries @xcite ..
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these measurements give the exciting prospect for determining a black hole s mass and spin , as well as tests of general relativity in the strong - field regime .
the strong gravitational fields near a black hole ( bh ) introduce significant deviations from newtonian physics , including the existence of an inner - most stable circular orbit ( isco ) , a feature absent in the classical kepler problem .
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11,924 |
Suppose that you have an abstract for a scientific paper: states supported by chaotic open quantum systems fall into two categories : a majority showing instantaneous ballistic decay , and a set of quantum resonances of classically vanishing support in phase space .
we present a theory describing these structures within a unified semiclassical framework .
emphasis is put on the quantum diffraction mechanism which introduces an element of probability and is crucial for the formation of resonances .
our main result are boundary conditions on the semiclassical propagation along system trajectories . depending on whether the trajectory propagation time is shorter or longer than the ehrenfest time ,
these conditions describe deterministic escape , or probabilistic quantum decay . .
And you have already written the first three sentences of the full article: quantum states populating open chaotic cavities decay to the outside environment and , thence , have the status of resonances . in spite of the ubiquity of the general setup
open quantum chaos is realized in many of the devices currently explored in mesoscopic physics , quantum optics , and cold atom physics salient features of these resonances are not fully understood . while the deep quantum regime ( the ehrenfest time , @xmath0 , marking the diffractive disintegration of minimal wave packages shorter than classical escape times , @xmath1 ) appears to be under reasonable control @xcite , it is the opposite , semiclassical limit which poses unsettled issues @xcite . broadly speaking , the states populating an open cavity can be grouped into two families : states evolving near classically and escaping deterministically after a classical flight time , and a fraction @xmath2 of quantum resonances , whose probabilistic decay is characterized by a finite imaginary offset @xmath3 to the real resonance energy @xmath4 . the most basic quantity characterizing the statistics of resonances of complex energy @xmath5 is the resonance density @xmath6 .
although the quantitative profile of that quantity is not fully understood , the density appears to be gapped against the real axis , @xmath7 ( the existence of rare midgap states notwithstanding @xcite . ).
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the integrated number of resonances at a given value of @xmath4 has been found to obey the so - called fractal weyl law , @xmath8 , where @xmath9 is a non - universal fractal exponent .
previous work on the phenomenon includes the formulation of lower bounds on the resonance gap @xcite , semiclassical approaches based on short periodic orbits _ trapped _ in the open system
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11,925 |
Suppose that you have an abstract for a scientific paper: the success of the first three years of operations of the lhc at center - of - mass energies of 7 and 8 tev radically changed the landscape of searches for new physics beyond the standard model and our very way of thinking about its possible origin and its hiding place . among the paradigms of new physics that have been probed quite extensively at the lhc , are various models that predict the existence of extra spatial dimensions . in this review ,
the current status of searches for extra dimensions with the cms detector is presented , along with prospects for future searches at the full energy of the lhc , expected to be reached in the next few years . published 4 may 2015 .
And you have already written the first three sentences of the full article: since the large hadron collider ( lhc ) started its first successful high - energy operations in 2010 , hopes that new physics beyond the standard model ( sm ) would appear any moment were running high . with the large accumulated amount of proton - proton data at center - of - mass energies @xmath0 and 8 tev , more and more sophisticated searches for new physics came along . among the theoretical paradigms tested to a great extent are the recent models with extra spatial dimensions , either flat or curved , that appeared about a decade ago and quickly gained a lot of attention from both theoretical and experimental communities .
these models offer a different solution to the infamous hierarchy problem " that plagues the sm , and promise an exciting possibility of studying quantum gravity at the lhc , including the most mysterious of its manifestations : the black holes . in this review ,
the current status of searches for extra spatial dimensions and quantum gravity with the compact muon solenoid ( cms ) detector at the lhc is presented ..
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while so far all these searches came empty - handed , several new experimental methods and techniques have been developed , which also apply to other searches for new physics . among these techniques
are an empirical method to predict qcd background in high - multiplicity events from low - multiplicity samples , as well as dedicated methods of reconstructing objects with high lorentz boost , which may be the key signature for discovery of high - mass resonances predicted in a variety of beyond the sm ( bsm ) models , including the extra dimensional paradigm .
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11,926 |
Suppose that you have an abstract for a scientific paper: we present a mapping of dynamical graphs and , in particular , the graphs used in the quantum graphity models for emergent geometry , to an ising hamiltonian on the line graph of a complete graph with a fixed number of vertices .
we use this method to study the properties of quantum graphity models at low temperature in the limit in which the valence coupling constant of the model is much greater than the coupling constants of the loop terms . using mean field theory
we find that an order parameter for the model is the average valence of the graph .
we calculate the equilibrium distribution for the valence as an implicit function of the temperature . in the approximation
in which the temperature is low , we find the first two taylor coefficients of the valence in the temperature expansion .
a discussion of the susceptibility function and a generalization of the model are given in the end . .
And you have already written the first three sentences of the full article: it is commonly agreed that at high spacetime curvatures , when the quantum effects of the gravitational field become significant , general relativity needs to be replaced by a quantum theory of gravity . in spite of progress in several directions , finding this new theory has proven a challenging problem for several decades .
current research in the field is paying substantial attention to the numerous indications that gravity may only be emergent , meaning that it is a collective , or thermodynamical , description of microscopic physics in which we do not encounter geometric or gravitational degree of freedom .
an analogy to illustrate this point of view is fluid dynamics and the transition from from thermodynamics to the kinetic theory ..
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what we currently know is the low energy theory , the analogue of fluid dynamics .
we are looking for the microscopic theory , the analogue of the quantum molecular dynamics . just as there are no waves in the molecular theory , we may not find geometric degree of freedom in the fundamental theory . not surprisingly
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11,927 |
Suppose that you have an abstract for a scientific paper: the detection and characterization of the first transiting super - earth , b , has required an unprecedented effort in terms of telescope time and analysis .
although the star does display a radial velocity signal at the period of the planet , this has been difficult to disentangle from the intrinsic stellar variability , and pinning down the velocity amplitude has been very challenging . as a result ,
the precise value of the mass of the planet and even the extent to which it can be considered to be confirmed have been debated in the recent literature , with six mass measurements published so far based on the same spectroscopic observations , ranging from about 2 to 8 earth masses . here
we report on an independent validation of the planet discovery , using one of the fundamental properties of a transit signal : its achromaticity .
we observed four transits of b at 4.5 and 8.0 with the infrared array camera ( irac ) onboard the space telescope , in order to determine whether the depth of the transit signal in the near - infrared is consistent with that observed in the bandpass , as expected for a planet .
we detected the transit and found an average depth of @xmath0 mmag at 4.5 , which is in good agreement with the depth of @xmath1 mmag ( ignoring limb darkening ) found by . the observations at 8.0 did not yield a significant detection .
the 4.5 observations place important constraints on the kinds of astrophysical false positives that could mimic the signal . combining this with additional constraints reported earlier
, we performed an exhaustive exploration of possible blends scenarios for b using the technique .
we are able to rule out the vast majority of false positives , and the remaining ones are found to be much less likely than a true transiting planet .
we thus validate b as a bona - fide planet with a very high degree of confidence , independently of any radial - velocity information .
our observations have additionally allowed us to significantly improve the....
And you have already written the first three sentences of the full article: among the known exoplanets , a few special cases stand out as the objects that inaugurated the study of the physics of earth - like exoplanets .
b @xcite is the first super - earth for which the mass and radius have been estimated , and provided the first real constraints on models of the formation , structure , and evolution of small and potentially rocky exoplanets .
kepler-10b has recently been announced as the first rocky planet found by the mission ( batalha et al ..
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2010 ) , with a mass of @xmath2 and a radius of @xmath3 .
we now also have examples of interesting planets that are intermediate in mass and radius between the earth and neptune , such as gj1214b , with @xmath4 ( charbonneau et al .
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11,928 |
Suppose that you have an abstract for a scientific paper: we consider first - order phase transitions of the universe in the radiation - dominated era .
we argue that in general the velocity of interfaces is non - relativistic due to the interaction with the plasma and the release of latent heat .
we study the general evolution of such slow phase transitions , which comprise essentially a short reheating stage and a longer phase equilibrium stage .
we perform a completely analytical description of both stages .
some rough approximations are needed for the first stage , due to the non - trivial relations between the quantities that determine the variation of temperature with time .
the second stage , instead , is considerably simplified by the fact that it develops at a constant temperature , close to the critical one .
indeed , in this case the equations can be solved exactly , including back - reaction on the expansion of the universe .
this treatment also applies to phase transitions mediated by impurities .
we also investigate the relations between the different parameters that govern the characteristics of the phase transition and its cosmological consequences , and discuss the dependence of these parameters with the particle content of the theory . .
And you have already written the first three sentences of the full article: it is well known that the universe could have undergone several phase transitions in the early stages of its history , most of them associated with the spontaneous symmetry breaking of some symmetry .
some examples are the quark - hadron phase transition at the qcd scale , the phase transitions associated to the electroweak @xmath0 symmetry breaking or to grand unified theories , and the peccei - quinn phase transition , related to the axion field and the strong cp problem .
cosmological phase transitions generically produce cosmic relics , such as topological defects , magnetic fields , or baryon number asymmetries , with potentially important cosmological consequences . the mechanisms for generating these relics build on the dynamics of the phase transition ..
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in a first - order phase transition the dynamics is essentially determined by the nucleation and expansion of bubbles . at zero temperature , when a true vacuum bubble nucleates , it rapidly begins to expand with almost the velocity of light @xcite . on the contrary , at high temperature ,
the bubble expands in a hot plasma , which is perturbed by the motion of the bubble walls .
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11,929 |
Suppose that you have an abstract for a scientific paper: we consider an inference on the eigenvalues of the covariance matrix of a multivariate normal distribution .
the family of multivariate normal distributions with a fixed mean is seen as a riemannian manifold with fisher information metric .
two submanifolds naturally arises ; one is the submanifold given by fixed eigenvectors of the covariance matrix , the other is the one given by fixed eigenvalues .
we analyze the geometrical structures of these manifolds such as metric , embedding curvature under @xmath0-connection or @xmath1-connection .
based on these results , we study 1 ) the bias of the sample eigenvalues , 2)the information loss caused by neglecting the sample eigenvectors , 3)new estimators that are naturally derived from the geometrical view .
msc(2010 ) _ subject classification _ : primary 62h05 ; secondary 62f12 + _ key words and phrases : _ curved exponential family , information loss , fisher information metric , embedding curvature , affine connection , positive definite matrix . .
And you have already written the first three sentences of the full article: consider a normal distribution with zero mean and an unknown covariance matrix , @xmath2 let denote the eigenvalues of @xmath3 by @xmath4 and eigenvectors matrix by @xmath5 , hence we have the spectral decomposition @xmath6 where @xmath7 means the diagonal matrix with the @xmath8th diagonal element @xmath9 .
it is needless to say that inference on @xmath3 is an important task in many practical situations in such a diversity of fields as engineering , biology , chemistry , finance , psychology etc .
especially we often encounter the cases where the property of interest depends on @xmath3 only through its eigenvalues @xmath10 ..
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we treat an inference problem on the eigenvalues in this paper .
geometrically viewed , the family of normal distributions @xmath11 is taken as a manifold ( say @xmath12 ) with a single coordinate system @xmath3 .
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11,930 |
Suppose that you have an abstract for a scientific paper: we extend the blume - emery - griffiths ( beg ) model to a two - component beg model in order to study 2d systems with two order parameters , such as magnetic superconductors or two - component bose - einstein condensates .
the model is investigated using monte carlo simulations , and the temperature - concentration phase diagram is determined in the presence and absence of an external magnetic field .
this model exhibits a rich phase diagram , including a second - order transition to a phase where superconductivity and magnetism coexist .
results are compared with experiments on cerium - based heavy - fermion superconductors . to study cold atom mixtures
, we also simulate the beg and two - component beg models with a trapping potential . in the beg model with a trap
, there is no longer a first order transition to a true phase - separated regime , but a crossover to a kind of phase - separated region .
the relation with imbalanced fermi - mixtures is discussed .
we present the phase diagram of the two - component beg model with a trap , which can describe boson - boson mixtures of cold atoms .
although there are no experimental results yet for the latter , we hope that our predictions could help to stimulate future experiments in this direction . .
And you have already written the first three sentences of the full article: mixtures of @xmath0he and @xmath1he atoms exhibit a rich phase diagram , where besides a normal phase , there is a phase where @xmath1he is superfluid , and a phase separated region of superfluid @xmath1he and normal @xmath0he.@xcite in 1971 , blume , emery and griffiths@xcite proposed a model to describe such mixtures .
they simplified the continuous phase of the superfluid order parameter such that it could acquire only two values .
although they made this very rough approximation and modelled the uniform system in a lattice , their results are very interesting ..
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qualitatively , they reproduced the right phases and the right orders of the phase transitions . furthermore ,
if disorder is introduced by placing the mixture into aerogel , after some modifications,@xcite the model can still yield the experimentally observed phase diagram.@xcite here , we generalize this model to a two - component case in order to describe systems with two order parameters and study the problem numerically , using monte carlo simulations .
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11,931 |
Suppose that you have an abstract for a scientific paper: feynman integrals may be represented by the mathematica packages ` ambre ` and ` mb ` as multiple mellin - barnes integrals . with the mathematica package ` mbsums ` we transform these mellin - barnes integrals into multiple sums . .
And you have already written the first three sentences of the full article: in recent years , there was remarkable progress in the development of ( semi-)automatized software for the numerical calculation of arbitrary , complicated feynman integrals .
basically , two approaches are advocated .
one relies on sector decomposition . for an introduction given at this conference and for further references.
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see @xcite .
we will report on the other approach , based on mellin - barnes representations @xcite .
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11,932 |
Suppose that you have an abstract for a scientific paper: it is by now well understood that quantum dissipative processes can be harnessed and turned into a resource for quantum - information processing tasks . in this paper
we demonstrate yet another way in which this is true by providing a dissipation - assisted protocol for the simulation of general markovian dynamics .
more precisely , we show how a suitable coherent coupling of a quantum system to a set of markovian dissipating qubits allows one to enact an effective liouvillian generator of any lindbladian form .
this effective dynamical generator arises from high - order virtual - dissipative processes and governs the system dynamics exactly in the limit of infinitely fast dissipation .
applications to the simulation of collective decoherence are discussed as an illustration .
quantum decoherence and dissipation have been regarded until recently purely detrimental to the aim of quantum information processing ( qip ) @xcite .
interactions with the environment in fact inevitably lead to entanglement between the quantum computing system and uncontrollable degrees of freedom .
this unwanted entanglement in turn results in a system subdynamics that is in general incoherent and irreversible : unitarity is quickly lost and with it the quantum information processing advantages e.g. , computational speed - ups , one was seeking for
. this state of affairs triggered a spectacular theoretical effort that led to the discovery of a host of techniques to tame decoherence @xcite as quantum error correction @xcite , decoherence - free subspaces @xcite , noiseless subsystems @xcite and holonomic quantum computation @xcite .
it is therefore a conceptually remarkable shift the recent realization that by reservoir - engineering dissipation can be harnessed and turned into a useful practical resource for qip ( see @xcite for an early pioneering insight ) .
for example one can dissipatively achieve quantum state preparation @xcite , quantum simulation @xcite , holonomic quantum computation @xcite and....
And you have already written the first three sentences of the full article: here we provide a proof of eq .
( [ 2nd - projection - th ] ) and an asymptotic ( large @xmath34 ) estimate of the constant @xmath148 let @xmath149 be the spectral projection of @xmath150 associated with the zero eigenvalue of @xmath13 . since , because of the lindblad structure , there is no nilpotent term associated with the zero eigenvalue , the perturbation theory reads , as shown in in t. kato , _ perturbation theory for linear operators _ , for small @xmath151 i.e. , large @xmath152 @xmath153 from the first equation it now follows ( for sufficiently large @xmath34 ) @xmath154 where @xmath155 is a suitable constant ( notice that @xmath156 ) . on the other hand , using @xmath157 and the definition @xmath158 for the dimensionful effective generator from the last equation in ( [ kato - pert ] ) it follows @xmath159 whence ( for small @xmath160 ) @xmath161 since @xmath162 one can write @xmath163 using @xmath164 with @xmath165 and @xmath166 and the bounds above it also follows that , for @xmath167 , @xmath168 where @xmath169 is a constant of that , for dimensional reasons , is @xmath170 i.e. , @xmath171 from ( [ triangle1 ] ) using @xmath172 and standard operator norm inequalities one finds @xmath173 notice that @xmath174 is the quantity showing up in the lhs of ( [ 2nd - projection - th ] ) namely is the quantity whose upper bound over @xmath175 $ ] we desire to show is @xmath105 now using the bounds ( [ ineq0 ] ) , ( [ ineq1]),([ineq2 ] ) and @xmath176 one finds @xmath177 where @xmath178 by moving to the dimensionless hamiltonian such that @xmath179 the inequality ( [ ineq3 ] ) becomes @xmath180 notice that the requirement of @xmath160 being sufficiently small used repeatedly in the above translate now in the adiabatic criterion " of @xmath34 being sufficiently large . finally by taking the supremum for @xmath181 $ ] one obtains @xmath182 setting @xmath183 completes the proof of ( [ 2nd - projection - th ] ) .
we directly compute the second order effective generator @xmath46 by acting on some state....
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one has @xmath186 where we have introduced notation @xmath187 , which only acts non - trivially on system @xmath63 for this set - up , i.e. @xmath188 ( following from @xmath189 , see @xcite ) .
acting with @xmath190 on this we can see that : @xmath191 where @xmath192 , and @xmath193 . in passing we notice that one can rewrite the system @xmath4 part of these equations in a more familiar form , using that without loss of generality @xmath194 and @xmath195 .
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11,933 |
Suppose that you have an abstract for a scientific paper: this article presents an overview of results pertaining to electronic structure , transport properties , and interaction effects in ballistic quantum wires with rashba spin splitting .
limits of weak and strong spin orbit coupling are distinguished , and spin properties of the electronic states elucidated . the case of strong rashba spin splitting
where the spin precession length is comparable to the wire width turns out to be particularly interesting .
hybridization of spin split quantum
wire subbands leads to an unusual spin structure where the direction of motion for electrons can fix their spin state .
this peculiar property has important ramifications for linear transport in the quantum wire , giving rise to spin accumulation without magnetic fields or ferromagnetic contacts .
a description for interacting rashba split quantum wires is developed , which is based on a generalization of the tomonaga luttinger model .
quasi1d spin
split subbands , spin
dependent transport , two band luttinger model 85.75.-d , 73.23.ad , 73.63.nm , 71.70.ej .
And you have already written the first three sentences of the full article: spin dependent transport in nanostructures has attracted a lot of interest @xcite recently . a familiar example are magnetoresistance effects in hybrid systems @xcite consisting of magnetic and nonmagnetics parts , which have important applications @xcite in present data storage technology . in such magnetoelectronics devices ,
spin dependent conductances arise due to the interplay between ferromagnetic exchange
field splitting and the pauli principle . a finite spin polarization of electric current _ in the normal parts of a hybrid system.
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_ is a prerequisite @xcite for magnetoresistance to occur .
strong efforts are currently directed towards doing magnetoelectronics using the recently discovered diluted magnetic semiconductor materials @xcite .
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11,934 |
Suppose that you have an abstract for a scientific paper: a contemporary and fundamental problem faced by many evolutionary biologists is how to puzzle together a collection @xmath0 of partial trees ( leaf - labelled trees whose leaves are bijectively labelled by species or , more generally , taxa , each supported by e.g.a gene ) into an overall parental structure that displays all trees in @xmath0 .
this already difficult problem is complicated by the fact that the trees in @xmath0 regularly support conflicting phylogenetic relationships and are not on the same but only overlapping taxa sets .
a desirable requirement on the sought after parental structure therefore is that it can accommodate the observed conflicts .
phylogenetic networks are a popular tool capable of doing precisely this .
however , not much is known about how to construct such networks from partial trees , a notable exception being the @xmath1-closure super - network approach and the recently introduced @xmath2-imputation approach . here
, we propose the usage of closure rules to obtain such a network .
in particular , we introduce the novel @xmath3-closure rule and show that this rule on its own or in combination with one of meacham s closure rules ( which we call the @xmath4-rule ) has some very desirable theoretical properties .
in addition , we use the @xmath4- and @xmath3-rule to explore the dependency of rivera et al.s `` ring of life '' on the fact that the underpinning phylogenetic trees are all on the same data set .
our analysis culminates in the presentation of a collection of induced subtrees from which this ring can be reconstructed .
k.t.huber + school of computing sciences , + university of east anglia , + norwich , nr5 7tj , + united kingdom .
+ email : [email protected] + fax : + 44 ( 0 ) 1603 593345 + we would prefer to submit the final manuscript in latex . .
And you have already written the first three sentences of the full article: phylogenetic trees have proved an important tool for representing evolutionary relationships . for a set @xmath5 of species ( or , more generally , taxa ) these
are formally defined as leaf - labelled trees whose leaves are bijectively labelled by the elements of @xmath5 .
advances in dna sequencing have resulted in ever more data on which such trees may be based ..
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computational limitations however combined with the need to understand species evolution have left biologists with the following fundamental problem which we will refer to as _ amalgamation problem _ : given a collection @xmath0 of phylogenetic trees , how can these trees be amalgamated into an overall parental structure that preserves the phylogenetic relationships supported by the trees in @xmath0 ?
the hope is that such a structure might help shed light on the evolution of the underlying genomes ( and thus the species ) . in the ideal case
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11,935 |
Suppose that you have an abstract for a scientific paper: carbon fiber support structures have become common elements of detector designs for high energy physics experiments .
carbon fiber has many mechanical advantages but it is also characterized by high conductivity , particularly at high frequency , with associated design issues .
this paper discusses the elements required for sound electrical performance of silicon detectors employing carbon fiber support elements .
tests on carbon fiber structures are presented indicating that carbon fiber must be regarded as a conductor for the frequency region of 10 to 100 mhz .
the general principles of grounding configurations involving carbon fiber structures will be discussed . to illustrate the design requirements , measurements performed with a silicon detector on a carbon fiber support structure at small radius
are presented .
a grounding scheme employing copper - kapton mesh circuits is described and shown to provide adequate and robust detector performance .
carbon fiber , silicon vertex detector , support structure , grounding , tevatron , fermilab , dzero 29.40.gx , 29.40.wk , 29.90.+r , 72.80.tm , 81.05.uw .
And you have already written the first three sentences of the full article: nowadays carbon fiber is a ubiquitous structural material used in a wide range of applications due to its high modulus and low mass .
it offers great flexibility in terms of tuning thermal and mechanical properties through the orientation and number of lay - ups of the fibers .
carbon fiber support structures have also become common elements of detector designs for high energy physics experiments and are especially prevalent in the design of silicon vertex detectors ..
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early examples of the use of carbon fiber in external support structures are the delphi silicon detector @xcite , and the space frames for the babar @xcite and cdf isl silicon detectors @xcite . in current designs ,
carbon fiber is integrated in the design of silicon detector modules , like the readout modules for the silicon tracker for the cms experiment @xcite .
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11,936 |
Suppose that you have an abstract for a scientific paper: the distance and redshift of a type ia supernova can be determined simultaneously through its multi - band light curves .
this fact may be used for imaging surveys that discover and obtain photometry for large numbers of supernovae ; so many that it would be difficult to obtain a spectroscopic redshift for each . using available supernova - analysis tools we find that there are several conditions in which a viable distance redshift can be determined .
uncertainties in the effective distance at @xmath0 are dominated by redshift uncertainties coupled with the steepness of the hubble law . by @xmath1
the hubble law flattens out and distance - modulus uncertainties dominate .
observations that give @xmath2 at peak brightness and a four - day observer cadence in each of @xmath3-bands are necessary to match the intrinsic supernova magnitude dispersion out to @xmath4 .
lower @xmath5 can be tolerated with the addition of redshift priors ( e.g. from a host - galaxy photometric redshift ) , observations in an additional redder band , or by focusing on supernova redshifts that have particular leverage for this measurement .
more stringent @xmath5 requirements are anticipated as improved systematics control over intrinsic color , metallicity , and dust is attempted to be drawn from light curves .
cosmology : distance scale , supernovae : general .
And you have already written the first three sentences of the full article: proposed wide - field imaging surveys will be able to discover and build light curves of thousands to hundreds of thousands of high - redshift type ia supernovae ( sne ia ) .
sne ia are established as excellent distance indicators having been used for both for the measurement of the hubble constant @xcite and for the discovery of the accelerated expansion of the universe @xcite .
there is thus interest in exploring how supernovae in new surveys can be used to improve the measurement of the expansion history of the universe and provide further insight into the physical cause of its acceleration ..
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although planned facilities and surveys provide straightforward harvesting of light curves for large numbers of supernovae , the corresponding spectroscopic observations used for redshift determination , supernova typing , and diagnostics are expensive .
it is unclear whether there will be available spectroscopic resources commensurate to the production of the imaging .
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11,937 |
Suppose that you have an abstract for a scientific paper: we present the results of microlens ray - tracing simulations showing the effect of absorbing material between a source quasar and a lensing galaxy in a gravitational lens system .
we find that , in addition to brightness fluctuations due to microlensing , the strength of the absorption line relative to the continuum varies with time , with the properties of the variations depending on the structure of the absorbing material .
we conclude that such variations will be measurable via uv spectroscopy of image a of the gravitationally lensed quasar q2237 + 0305 if the lyman alpha clouds between the quasar and the lensing galaxy possess structure on scales smaller than @xmath0 pc .
the time scale for the variations is on the order of order years to decades , although very short term variability can occur . while the lyman alpha lines may not be accessible at all wavelengths , this approach is applicable to any absorption system , including metal lines .
[ firstpage ] gravitational lensing - quasars : individual : q2237 + 0305 - quasars : absorption lines - intergalactic medium .
And you have already written the first three sentences of the full article: the lyman alpha ( ly@xmath1 ) forest is an absorption phenomenon which is observed in the spectra of many high redshift quasars .
it arises due to absorption by galactic and intergalactic neutral hydrogen between a quasar and an observer [ see for a recent review ] .
as the universe expands , photons from the quasar are redshifted , and therefore absorption by clouds at different cosmological distances cause absorption at different wavelengths in the spectrum ..
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the resulting spectrum contains many absorption lines blueward of the ly@xmath1 emission line of the quasar , and the structure of the absorbing material along the line of sight is imprinted on the spectrum ( e.g. * ? ? ?
numerical simulations of cosmological structure formation predict the large scale structure of the gas which can then be compared with observations of quasar spectra @xcite .
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11,938 |
Suppose that you have an abstract for a scientific paper: using a complete , magnitude - limited sample of active galaxies from the sloan digital sky survey ( sdss ) we show that the fraction of broad - line ( type 1 ) active galactic nuclei increases with luminosity of the isotropically - emitted [ o iii ] narrow emission line .
our results are quantitatively in agreement with , and far less uncertain than , similar trends found from studies of x - ray and radio - selected active galaxies . while the correlation between broad - line fraction and luminosity is qualitatively consistent with the receding torus model , its slope is shallower and we therefore propose a modification to this model where the height of the torus increases slowly with agn luminosity .
we demonstrate that the faint - end slope of the agn luminosity function steepens significantly when a correction for ` missing ' type 2 objects is made and that this can substantially affect the overall agn luminosity density extrapolated from samples of more luminous objects .
galaxies : active galaxies : seyfert .
And you have already written the first three sentences of the full article: active galactic nuclei ( agns ) were once thought to be a rare phenomenon whose major cosmological impact was in their ability to be seen out to great distances .
however , the discovery of supermassive black holes in the centres of nearby galaxies has led to the view that all galaxies went through an active phase .
furthermore , calculations have shown that the energy produced during this phase is sufficient to drive material out of the host galaxy ( silk & rees 1998 ; fabian 1999 ) ..
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feedback such as this can explain the tightness of the correlation between the masses of the black hole and host galaxy bulge ( e.g. , mclure & dunlop 2002 ) , and it has been suggested that such a process may perform a key role in shaping the galaxy luminosity function ( benson et al .
2003 ) .
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11,939 |
Suppose that you have an abstract for a scientific paper: understanding of charge transport mechanisms in nanoscale structures is essential for the development of molecular electronic devices .
charge transport through 1d molecular systems connected between two contacts is influenced by several parameters such as the electronic structure of the molecule and the presence of disorder and defects . in this work ,
we have modeled 1d molecular wires connected between electrodes and systematically investigated the influence of both soliton formation and the presence of defects on properties such as the conductance and the density of states .
our numerical calculations have shown that the transport properties are highly sensitive to the position of both solitons and defects .
interestingly , the introduction of a single defect in the molecular wire which divides it into two fragments both consisting of an odd number of sites creates a new conduction channel in the center of the band gap resulting in higher zero - bias conductance than for defect free systems .
this phenomenon suggests alternative routes toward engineering molecular wires with enhanced conductance . .
And you have already written the first three sentences of the full article: the investigation of quantum transport through molecular systems has become an important research field in the last few decades.@xcite progress in measuring and fabrication techniques@xcite has led to the continuous miniaturization of electronic devices , which have reached the point where quantum effects are important .
for example , semiconductor devices have been reduced in size to the nanoscale@xcite and even to the atomic scale.@xcite in addition to the report of metal atomic wires,@xcite stable and rigid carbon atomic chains have been reported recently.@xcite a key idea behind the advances in the understanding of charge transport through molecular systems is based on the view proposed by landauer , _ conductance is transmission_.@xcite potential applications of molecular devices range from novel computer architectures@xcite to chemical sensors@xcite and medical diagnostics @xcite . among the various molecular devices , 1d conductors such as molecular wires,@xcite
have been considered to be one of the most fundamental components for nanotechnology . due to the reduction of size and dimensions of materials ,.
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1d systems show sensitive response to external field or intrisic characteristics , which can be exploited for the development of molecular devices such as biological sensors@xcite with high sensitivity .
polymers are one of the most promising materials for acting as 1d conductors . their applicability@xcite ranges from displays@xcite to thin film transistors,@xcite photovoltaics,@xcite and solar cells.@xcite the compatibility of polymer materials with light - weight , mechanically flexible plastic substrates and new fabrication methods make them possible candidates for future electronic devices .
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11,940 |
Suppose that you have an abstract for a scientific paper: we present results from a detailed analysis of our 2016 _ xmm - newton _ observation of the narrow - line seyfert 1 galaxy pg 1404 + 226 which showed a large - amplitude , rapid x - ray variability by a factor of @xmath0 in @xmath1 ks .
we use this variability event to investigate the origin of the soft x - ray excess emission and the connection between the disk , hot corona and the soft excess emitting region through uv / x - ray cross - correlation , time - resolved spectroscopy and root mean square ( rms ) spectral modelling . the weakly variable uv emission ( @xmath2=3.9@xmath3 )
appears to lead the strongly variable x - ray emission ( @xmath4=89.0@xmath5 ) by @xmath6 ks .
such a uv lead is consistent with the crossing time ( @xmath7 ks ) of the seed photons from the disk to a compact ( @xmath8 ) hot corona and the time required for their thermal comptonization ( @xmath9 ks ) giving rise to the x - ray power - law emission .
the strong soft x - ray excess below 1 kev seen in the mean x - ray spectrum as well as in the time - resolved spectra is well described by both the intrinsic disk comptonization and the blurred reflection models .
the soft excess emission is found to vary together with the power - law component as @xmath10 .
the x - ray fractional rms spectrum shows an increase in variability with energy which can be described only in the framework of blurred reflection model in which both the intrinsic continuum and the reflected emission are highly variable in normalization only and are perfectly coupled with each other .
our results suggest that accretion disk provides the seed photons for thermal comptonization giving rise to the x - ray power - law component which in turn illuminates the innermost accretion disk and gives rise to the soft x - ray excess emission .
[ firstpage ] .
And you have already written the first three sentences of the full article: the narrow - line seyfert 1 ( nls1 ) galaxies , a subclass of active galactic nuclei ( agn ) have been the centre of interest because of their extreme variability in the x - ray band @xcite .
the defining properties of this class of agn are : balmer lines with full width at half - maximum fwhm(h@xmath11 ) @xmath12 km s@xmath13 @xcite , strong permitted optical / uv fe ii emission lines @xcite and weaker [ oiii ] emission @xmath14\lambda5007}{h_{\beta}}\leq3 $ ] @xcite .
the x - ray spectra of seyfert galaxies show a power - law like primary continuum which is thought to arise due to thermal comptonization of the optical / uv seed photons in a corona of hot electrons surrounding the central supermassive black hole ( e.g.@xcite ) ..
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the optical / uv photons are thought to arise from an accretion disk but direct observational evidence is lacking .
similarly , the interplay between the accretion disk and the hot corona is not well understood .
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11,941 |
Suppose that you have an abstract for a scientific paper: a basic distinction , long overlooked , between the conventional , `` idealistic '' formulation of qcd , and a more `` realistic '' formulation is brought into focus by a rigorous , non - perturbative , gauge - invariant evaluation of the schwinger solution for the qcd generating functional in terms of exact fradkin representations for the green s functional @xmath0 and the vacuum functional @xmath1 $ ] . the quanta of all ( abelian ) quantized fields may be expected to obey standard quantum - mechanical measurement properties , perfect position dependence at the cost of unknown momenta , and vice - versa , but this is impossible for quarks since they always appear asymptotically in bound states , and their transverse position or momenta can never , in principle , be exactly measured .
violation of this principle produces an absurdity in the exact evaluation of each and every qcd amplitude .
we here suggest a phenomenological change in the basic qcd lagrangian , such that a limitation of transverse precision is automatically contained in a proposed ` realistic ' theory , with the function essential to quark binding into hadrons appearing in the new lagrangian .
all absurdities in estimates of all `` realistic '' qcd amplitudes are then removed , and one obtains the possibility of hadron formation by appropriate quark binding potentials , and nucleon scattering and binding by effective , yukawa - type potentials ; the first of these potentials is constructed , in detail , in a following article . .
And you have already written the first three sentences of the full article: this is the third paper of a series @xcite describing a new , gauge - invariant , non - perturbative formulation of qcd , which provides analytic estimates of any amplitude which sums over all relevant feynman graphs , including all possible gluon exchanges between appropriate quarks ( q ) and antiquarks ( @xmath2 ) .
all cubic and quartic gluon interactions are included .
results are expressed in terms of fradkin s most useful functional representations @xcite of the green s function @xmath3 | y \rangle$ ] , @xmath4 = [ m + \gamma \cdot ( \partial - ig a \cdot \lambda)]^{-1}\ ] ] and the closed - loop , or vacuum functional @xmath1 $ ] , @xmath5 = { { \mathrm{tr}\ , } } { \ln{[1 - i g ( \gamma \cdot a \cdot \lambda ) \ , \mathbf{s}_{c } ] } } , \quad \mathbf{s}_{c } = \mathbf{g}_{c}[0],\ ] ] where @xmath6 represents a given vector potential . since the fradkin representations for these quantities are of potential theory origin , they have relatively simple approximations in different physical situations @xcite , especially at high energies where they effectively generate eikonal models . it should be understood that we are here dealing with the simplest form of `` textbook qcd '' : one type of quark coupled to multicolored gluons . flavors and electroweak interactions.
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are to be added later on .
this new formulation provides an exact statement of what may be expected from conventional , or `` ideal '' qcd , where the quanta of the quark field operators are expected to have the same quantum - mechanical measurement properties as , _
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11,942 |
Suppose that you have an abstract for a scientific paper: the cascade mass reconstruction approach was applied to simulated production of the lightest stop quark at the lhc in the cascade decay @xmath0 with top quarks decaying into hadrons .
the stop quark mass was reconstructed assuming that the masses of gluino , slepton and of the two lightest neutralinos were reconstructed in advance .
a data sample set for the su3 model point containing 400k susy events was generated which corresponded to an integrated luminosity of about 20 @xmath1 at 14 tev .
these events were passed through the acerdet detector simulator , which parametrized the response of a generic lhc detector .
the mass of the @xmath2 was reconstructed with a precision of about @xmath3 . .
And you have already written the first three sentences of the full article: if supersymmetry exists at an energy scale of 1 tev , the study of third generation sleptons and squarks at the lhc is of a special interest .
their masses can be very different from that of sparticles of the first and second generation , because of the effects of large yukawa and soft couplings as can be seen from the renormalization group equations .
furthermore they can show large mixing in pairs @xmath4 and @xmath5 . a detailed discussion of possible susy effects at the lhc is given in @xcite ..
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in this paper we consider the mass reconstruction of the lightest stop quark ( @xmath2 ) in the cascade decay @xmath6 with the top quarks decaying into hadrons . the gluino decay chain ( [ eq - chain ] ) is represented in fig . [ fig - chain ] , in which all final state particles are explicitly shown .
here , the considered leptons are electrons and muons ( @xmath7 e , ) .
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11,943 |
Suppose that you have an abstract for a scientific paper: professional societies and collaboratives have called for the incorporation of more quantitative skills , such as mathematical modeling , securely into the foundation and throughout undergraduate biology programs .
however , the integration of modeling both within and between mathematics and biology curricula remains limited .
one barrier to integration comes from differing perceptions about the nature of modeling , thereby limiting communication between disciplines . in this paper
, we extend the `` rule of five , '' initially used in calculus reform efforts , to build a modeling framework that explicitly separates and defines models as representations and modeling as a process .
we discuss benefits to student learning and cross - disciplinary communication . .
And you have already written the first three sentences of the full article: from computer games and medicine to weather predictions and new technologies , nearly every aspect of our lives is influenced by mathematical modeling .
a primary barrier to forward progress in teaching mathematical modeling across our partner disciplines is misconceptions and biases around what constitutes modeling .
we ( the co - authors ) are part of an interdisciplinary working group at the national institute for mathematical and biological synthesis ( nimbios ) that has brought together mathematicians , biologists , and education researchers to address teaching quantitative biology , especially modeling ..
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each of us has experienced reaching out to collaborate with a member of another discipline , only to have the conversation shut down before it has really started because of the naive assumptions we make about the other s discipline .
we posit that if mathematicians and biologists alike can improve their understanding of the similarities and differences in their approaches to and language around modeling , then each discipline will play a more effective role in advancing the other @xcite , and we will be able to teach this valuable skill more effectively . in this paper
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11,944 |
Suppose that you have an abstract for a scientific paper: recent studies demonstrated that there may appear different novel states in correlated systems close to localized itinerant crossover .
especially favourable conditions for that are met in low - dimensional and in frustrated systems . in this paper i discuss on concrete examples some of such novel states .
in particular , for some spinels and triangular systems there appears a `` partial mott transition '' , in which first some finite clusters ( dimers , trimes , tetramers , heptamers ) go over to the itinerant regime , and the real bulk mott transition occurs only later .
also some other specific possibilities in this crossover regime are shortly discussed , such as spin - peierls peierls transition in tiocl , spontaneous charge disproportionation in some cases , etc . .
And you have already written the first three sentences of the full article: the subdivision of electronic states into delocalized , itinerant , and localized , strongly correlated states is one of the most fundamental ones in the description of solids .
crudely , delocalized states exist when the intersite electron hopping is larger than the typical electron
electron interaction energy , and localized states exist in the opposite limit . in quantum chemistry.
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these two limits correspond e.g. to the description of electrons in terms of molecular orbitals ( mulliken description , known in chemistry as molecular orbital linear combination of atomic orbitals ( mo lcao ) method ) , and strongly correlated electrons are described by the heitler london approximation . for concentrated solids
these two regimes give either standard band systems ( metals or semiconductors ) , or mott insulators .
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11,945 |
Suppose that you have an abstract for a scientific paper: conductive organic polymers can be formulated with polymers that incorporate fine dispersed metallic particles . in this work ,
we present a general model for ferrogels which are chemically cross - linked polymer networks swollen with a ferrofluid .
our aim is to study the effect of the shape and/or material ( conductivity ) anisotropy on the effective electrical conductivity of the ferrogel in the presence of an external magnetic field .
our theory can reproduce the known results , and provides a link between the particle property and orientation distribution and the effective electrical conductivity . to this end
, we find that material ( conductivity ) anisotropies are more important to yield a high effective electrical conductivity than shape anisotropies , while magnetic fields can offer a correction . .
And you have already written the first three sentences of the full article: conductive polymers @xcite have received much attention due to its extensive industrial applications ( for a review , see ref .
@xcite ) , such as in nonlinear optical waveguides , vapor - phase detectors , twisted nematic liquid crystal displays , and so on . in fact
, the conductive organic polymers @xcite can be formulated with polymers that incorporate conductive additives such as carbon black @xcite or fine dispersed metallic particles @xcite ..
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this is because the presence of certain additives in the polymer can enhance the effective electrical conductivity . in particular , recently organic polymer composites filled with conductive metallic particles received much attention in scientific research @xcite .
for such polymer composites , their electrical characteristic are close to that of metals , whereas the mechanical property and processing method are typical for plastics @xcite .
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11,946 |
Suppose that you have an abstract for a scientific paper: we work out a semiclassical theory of shot noise in ballistic @xmath0 semiconductor structures aiming at studying two fundamental physical correlations coming from pauli exclusion principle and long range coulomb interaction .
the theory provides a unifying scheme which , in addition to the current - voltage characteristics , describes the suppression of shot noise due to pauli and coulomb correlations in the whole range of system parameters and applied bias .
the whole scenario is summarized by a phase diagram in the plane of two dimensionless variables related to the sample length and contact chemical potential . here
different regions of physical interest can be identified where only coulomb or only pauli correlations are active , or where both are present with different relevance .
the predictions of the theory are proven to be fully corroborated by monte carlo simulations . .
And you have already written the first three sentences of the full article: ballistic conductors are characterized by an active region where carriers , once injected by contacts , move without suffering any scattering from contact to contact , i.e. the carrier mean free path is much longer than the sample characteristic dimensions . in metals ,
ballistic transport is usually studied in point contacts.@xcite such contacts allow the analysis of elastic and inelastic scattering processes by means of the so called point contact spectroscopy.@xcite since the fermi wavelength in metals is very small ( @xmath1 ) , the nature of carrier transport is semiclassical and quantum effects related to the wave nature of the electrons can be disregarded . in semiconductors , ballistic transport has been investigated in bulk materials,@xcite point contacts@xcite and two dimensional electron gases;@xcite some studies have allowed the development of ballistic emission spectroscopy@xcite for the analysis of semiconductor heterointerfaces .
moreover , a variety of ballistic electron devices with promising performances have been realized@xcite or proposed.@xcite since the fermi wave length in semiconductors can be as large as 40 @xmath2 , the nature of the carrier transport can be either semiclassical or quantum depending on the characteristic sample dimensions , @xmath3 , with respect to the fermi wave length , @xmath4 . for @xmath5 transport.
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is semiclassical , while for @xmath6 transport is quantum . from a fundamental point of view
, the study of non - equilibrium electronic noise ( shot noise)@xcite of ballistic conductors in the semiclassical transport regime offers a unique scenario where the simultaneous effect of two fundamental physical interactions , namely the long range coulomb interaction and the pauli exclusion principle , can be investigated . on the one hand ,
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11,947 |
Suppose that you have an abstract for a scientific paper: so far , numerical studies of double - diffusive layering in turbulent convective flows have neglected the effects of rotation .
we undertake a first step into that direction by investigating how coriolis forces affect a double - diffusive layer inside a rotating spherical shell . for this purpose
we have run simulations in a parameter regime where these layers are expected to form and successively increased the rate of rotation with the result that fast rotation is found to have a similar stabilising effect on the overall convective flux as an increase of the stability ratio @xmath0 has in a non - rotating setup .
we have also studied to what extent the regimes of rotational constraints suggested by @xcite for rotation in the case of rayleigh - bnard convection are influenced by double - diffusive convection : their classification could also be applicable to the case of double - diffusive convection in a spherical shell if it is extended to be also a function of the stability ratio @xmath0 . furthermore , we examined the ratio of saline and thermal nusselt numbers and compared our results with models of @xcite , @xcite and @xcite .
we find our data to be fitted best by spruit s model .
our result that fast rotation further decreases the convective transport , which is already lowered by double - diffusive convection , could play a major role for e.g. the modeling of the interior of some rapidly rotating giant planets , as gaseous giant planets have recently been proposed to be influenced by double - diffusive convection . .
And you have already written the first three sentences of the full article: the physical process known as double - diffusive convection was first described in the 1950 s by @xcite who observed the effect in an experiment . shortly afterwards
, it was also found in astrophysics when the first detailed stellar models were computed and @xcite found irregularities in their calculations concerning whether or not a zone with a gradient in molecular weight was stable according to the ledoux criterion or the schwarzschild criterion . but
even more than fifty years after its discovery , the field is still actively researched which is due to two reasons : on the one hand it lacked immediate practical incentives that have accelerated the development of other branches of fluid mechanics . on the other hand ,.
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numerical simulations were not possible for a long time because of the considerable computational expenses they demand .
for a summary of the historical development of the area see the paper by @xcite , for a recent physical review about semiconvection see @xcite .
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11,948 |
Suppose that you have an abstract for a scientific paper: we investigate the x - ray spectra of the type-2 seyfert galaxies ngc 7172 and eso 103-g35 , using _ bepposax _ observations , separated by approximately one year .
we find that the x - ray spectra of both ngc 7172 and eso 103-g35 can be well fitted using a power - law model with an fe k@xmath0 emission line at 6.4 kev .
we did not find any statistically significant evidence for the existence of a reflection component in the x - ray spectra of these two galaxies .
the continuum flux has decreased by a factor of approximately two during this period , in both objects .
however , the spectral index as well as the absorption column have remained constant .
we find weak evidence for the decrease of the normalization of the fe k@xmath0 emission line in a similar manner to the continuum in ngc7172 .
we also report evidence for a broad fe k@xmath0 confirming previous observations .
in contrast , in the case of eso 103-g35 the line flux does not change while its width remains unresolved .
2@xmath1 = = = 1=1=0pt = 2=2=0pt = 2=2=0pt galaxies : active - quasars : general - x - rays : general .
And you have already written the first three sentences of the full article: in recent years x - ray missions such as and have demonstrated that seyfert-2 galaxies have a very complex x - ray spectrum ( see mushotzky , pounds & done 1993 for a recent review ) . in particular
their spectrum contains at least the following features : a ) a power - law continuum with slope @xmath2 absorbed by a very large column ( @xmath3 ) ( eg turner & pounds 1988 ) ; this obscuring screen is probably associated with a molecular torus .
b ) an fek line at 6.4 kev ie originating from neutral fe c ) a spectral curvature ( hump ) above 10 kev ; this is generally believed to originate from reflection of the power - law component on cold material ( eg lightman & white 1988 , george & fabian 1991 ) ..
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in contrast to the recent progress in understanding the spectral features of seyfert-2 galaxies , our knowledge of their x - ray variability properties remains scanty . usually , this has been based on comparison of the x - ray flux between observations from different missions spanning time intervals of several years .
recently , turner et al . (
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11,949 |
Suppose that you have an abstract for a scientific paper: vector modes are spatial modes that have spatially inhomogeneous states of polarization , such as , radial and azimuthal polarization .
they can produce smaller spot sizes and stronger longitudinal polarization components upon focusing . as a result
, they are used for many applications , including optical trapping and nanoscale imaging . in this work ,
vector modes are used to increase the information capacity of free space optical communication via the method of optical communication referred to as mode division multiplexing . a mode ( de)multiplexer for vector modes based on a liquid crystal technology referred to as a @xmath0-plate
is introduced . as a proof of principle , using the mode (
de)multiplexer four vector modes each carrying a 20 gbit / s quadrature phase shift keying signal on a single wavelength channel ( @xmath11550 nm ) , comprising an aggregate 80 gbit / s , were transmitted @xmath21 m over the lab table with @xmath3 - 16.4 db ( @xmath4 ) mode crosstalk .
bit error rates for all vector modes were measured at the forward error correction threshold with power penalties @xmath3 3.41db . .
And you have already written the first three sentences of the full article: mode division multiplexing ( mdm ) is the method of optical communication where spatial modes are used as information channels carrying independent data streams . in general
, mdm can potentially increase the information capacity of optical communication in an amount proportional to the number of modes used .
mdm has been used in optical fiber communication ; for comprehensive reviews see @xcite ..
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potentially , mdm can also be used in free space optical communication ( fso ) @xcite .
polarization division multiplexing and wavelength division multiplexing have been used to increase the information capacity of fso @xcite . by definition
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11,950 |
Suppose that you have an abstract for a scientific paper: we derive a general capacitive interaction model for an antidot - based interferometer in the integer quantum hall regime , and study aharonov - bohm resonances in a single antidot with multiple bound modes , as a function of the external magnetic field or the gate voltage applied to the antidot .
the pattern of aharonov - bohm resonances is significantly different from the case of noninteracting electrons .
the origin of the difference includes charging effects of excess charges , charge relaxation between the bound modes , the capacitive interaction between the bound modes and the extended edge channels nearby the antidot , and the competition between the single - particle level spacing and the charging energy of the antidot .
we analyze the patterns for the case that the number of the bound modes is 2 , 3 , or 4 .
the results agree with recent experimental data . .
And you have already written the first three sentences of the full article: an antidot is a potential hill in a two - dimensional electron system .
when a strong perpendicular magnetic field @xmath0 is applied , the system shows the quantum hall effects , and there appear bound modes of quantum hall edge states around the antidot .
as the modes enclose magnetic flux , they are governed by the aharonov - bohm ( ab ) effect ..
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@xcite when the bound modes couple with extended edge channels via tunneling , the antidot shows ab resonance peaks in electron conductance , as a function of @xmath0 or the gate voltage @xmath1 applied to the antidot .
an antidot is a useful tool for detecting and studying localized quantum hall edge states .
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11,951 |
Suppose that you have an abstract for a scientific paper: with the semiclassical landau - vlasov transport model we studied the stopping observable @xmath0 , the energy - based isotropy ratio , for the @xmath1xe+@xmath2sn reaction at beam energies spanning 12@xmath3 to 100@xmath3 mev .
we investigated the impacts of the nonlocality of the nuclear mean field , of the in - medium modified nucleon - nucleon ( @xmath4 ) cross section and of the reaction centrality .
a fixed set of model parameters yields @xmath0 values that favorably compare with the experimental ones , but only for energies below the fermi energy @xmath5 . above @xmath5 agreement is readily possible , but by a smooth evolution with energy of the parameter that controls the in - medium modification of @xmath4 cross section . by comparing the simulation correction factor @xmath6 applied to the free @xmath4 cross section with the one deduced from experimental data [ phys .
rev .
c*90 * , 064602 ( 2014 ) ] , we infer that the zero - range mean field almost entirely reproduces it .
also , in accordance with what has been deduced from experimental data , around @xmath5 a strong reduction of the free @xmath4 cross section is found . in order to test the impact of sampling central collisions by multiplicity an event generator ( hipse )
was used .
we obtain that high multiplicity events are spread over a broad impact parameter range , but it turns out that this has a small effect on the observable @xmath0 and , thus , on @xmath6 as well . .
And you have already written the first three sentences of the full article: the ratio between transverse and longitudinal components of kinematical observables is a measure of the conversion of the initial entrance channel motion into intrinsic degrees of freedom in heavy - ion collisions ( hics ) .
such an observable gives an insight on the rate of a system s equilibration , of the dissipation of the available energy , as well as of hic stopping power @xcite .
thanks to such an observable , the fopi collaboration has evidenced partial nuclear transparency in hic in the beam - energy range @xmath70.1@xmath31@xmath3 gev @xcite ..
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more recently , by examining the ratio of transverse to longitudinal energy @xmath0 and linear momentum @xmath8 for the most violent hics , the indra collaboration has revealed a substantial reduction of the nuclear stopping power at @xmath710@xmath3100@xmath3 mev@xcite .
this stopping observable reaches a minimum around the fermi energy @xmath5 and stagnates or very weakly increases with the further increase of @xmath9 at least up to 100@xmath3 mev , the upper limit of the energy range available in this study .
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11,952 |
Suppose that you have an abstract for a scientific paper: the sloan digital sky survey ( sdss ) has scanned the entire region containing the draco dwarf spheroidal galaxy to @xmath0 magnitude in @xmath1 .
we present a catalog of stars found in a 453 square arcminute , elliptical region centered on the draco dwarf spheroidal galaxy .
objects in the catalog are matched with five previously published catalogs .
the catalog contains sdss photometry for 5634 individual objects , and also the photometry from matches to any of the other catalogs .
a comparison of the photometry between catalogs allows us to identify 142 candidate variable objects .
one hundred and twelve of the suspected variables have colors consistent with rr lyrae variables . .
And you have already written the first three sentences of the full article: the draco dwarf spheroidal companion to the milky way , at a distance of about 82 kpc @xcite , was discovered fifty years ago from examination of palomar observatory sky survey schmidt plates @xcite .
the horizontal branch for this dwarf galaxy is located at @xmath2 and it covers more than 1/3 of a square degree on the sky .
draco is one of the nearest of the galaxy s known dwarf spheroidal companions and is among the faintest known galaxies , with a luminosity of @xmath3 @xcite ..
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dwarf spheroidal galaxies typically contain many variable stars , predominately the rr lyrae variables typical of older , metal - poor stellar populations @xcite .
draco is no exception .
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11,953 |
Suppose that you have an abstract for a scientific paper: we study the structure of a social network of strong ties ( trust network ) investigating its property of connectedness versus fragmentation . to this purpose
we analyse an extensive set of census data , about marrying or having children with immigrants , collected by italian national statistical institute for all italian municipalities from 2001 to 2011 . not using neither obtaining personal local information but only average ones
, our method fully complies with privacy and confidentiality .
our findings show that large cities display the behaviour of highly fragmented trust networks where individuals face possible phenomena of alienation .
smaller cities and villages instead behave like fully connected social systems with a rich tie structure , where isolation is rare or completely absent .
while confirming classical sociological theories on alienation in large urban areas our approach provides a quantitative method to test them and a predictive tool for policy makers . human choices ,
as clearly elucidated in the work of max weber @xcite , can be distinguished according to the fact that they are _ social actions _ or not .
sometimes , mostly when the matter of the choice is simple and the conclusions can be reached with elementary reasoning , we draw a decision by ourselves , without relying on other opinions and only counting on our pre - existing cultural background . some other times ( the case of social action ) , when the choice is of complex nature or when the information we have is not enough to draw a rational conclusion we proceed , _ whenever possible _ , by relating to others either by imitation or seeking for interaction and consensus .
those two types of individual choice mechanisms lead to two different emerging collective social behaviour each displaying peculiar features .
the case of independent choices usually come with smooth , locally linear , behaviour while the other may present different characteristics , including tipping points , according to the nature and....
And you have already written the first three sentences of the full article: we consider here a database on mixed marriages and newborns to mixed couples , annually recorded by istat ( italian institute of statistics ) for all italian municipalities in the time period from 2001 to 2011 . in that time span
documented foreign born population has grown in italy from just over 1 million to almost 4 millions people , corresponding to an increase from @xmath1 to over @xmath2 of the total resident population .
these figures do not include illegal immigrants whose numbers are difficult to determine . although there are immigrants from almost all nations , the communities with higher presence are from romania ( @xmath3,@xmath4 in @xmath5 , i.e @xmath6 of the total population of immigrants ) , followed by albania ( @xmath7,@xmath4 in @xmath5 , i.e @xmath8 ) , morocco ( @xmath9,@xmath4 in @xmath5 , i.e @xmath10 ) , and china ( @xmath11,@xmath4 in @xmath5 , i.e @xmath12 ) ..
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the geographical distribution of immigrants is largely not homogeneous : @xmath13 lives in the northern and central part of the country ( the most economically developed areas ) , while @xmath14 lives in the south .
the dataset contains over @xmath15,@xmath16,@xmath4 data , yearly describing - for each of the @xmath17,@xmath16 municipalities - the total population , the number of immigrants , the number of marriages and newborns originating from different types of couples ( either mixed or not ) . for each municipality
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11,954 |
Suppose that you have an abstract for a scientific paper: in this paper we discuss a special class of beltrami coefficients whose associated quasiconformal mapping is bilipschitz .
a particular example are those of the form @xmath0 , where @xmath1 is a bounded domain with boundary of class @xmath2 and @xmath3 a function in @xmath4 satisfying @xmath5 .
an important point is that there is no restriction whatsoever on the @xmath4 norm of @xmath3 besides the requirement on beltrami coefficients that the supremum norm be less than @xmath6 .
the crucial fact in the proof is the extra cancellation enjoyed by even homogeneous caldern - zygmund kernels , namely that they have zero integral on half the unit ball .
this property is expressed in a particularly suggestive way and is shown to have far reaching consequences .
an application to a lipschitz regularity result for solutions of second order elliptic equations in divergence form in the plane is presented . .
And you have already written the first three sentences of the full article: consider the beltrami equation @xmath7 where @xmath8 is a lebesgue measurable function on the complex plane @xmath9 satisfying @xmath10 . according to a remarkable old theorem of morrey @xcite
there exists an essentially unique function @xmath11 in the sobolev space @xmath12 ( functions with first order derivatives locally in @xmath13 ) which satisfies almost everywhere and is a _ homeomorphism of the plane_. these functions are called quasiconformal .
it turns out that @xmath11 may change drastically the hausdorff dimension of sets ..
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indeed , sets of arbitrarily small positive hausdorff dimension may be mapped into sets of hausdorff dimension as close to @xmath14 as desired ( and the other way around by the inverse mapping ) .
there has been during the last decades much hard and penetrating work in understanding how @xmath11 distorts sets ( see , for instance @xcite and the references given there or @xcite for a recent result ) .
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11,955 |
Suppose that you have an abstract for a scientific paper: finding satisfying assignments for the variables involved in a set of constraints can be cast as a ( bounded ) _ model generation _ problem : search for ( bounded ) models of a theory in some logic .
the state - of - the - art approach for bounded model generation for rich knowledge representation languages like and and a csp modeling language such as zinc , is _ ground - and - solve _ : reduce the theory to a ground or propositional one and apply a search algorithm to the resulting theory .
an important bottleneck is the blow - up of the size of the theory caused by the grounding phase .
_ lazily grounding _ the theory during search is a way to overcome this bottleneck .
we present a theoretical framework and an implementation in the context of the knowledge representation language . instead of grounding all parts of a theory , _ justifications _
are derived for some parts of it . given a partial assignment for the grounded part of the theory and valid justifications for the formulas of the non - grounded part , the justifications provide a recipe to construct a complete assignment that satisfies the non - grounded part .
when a justification for a particular formula becomes invalid during search , a new one is derived ; if that fails , the formula is split in a part to be grounded and a part that can be justified .
experimental results illustrate the power and generality of this approach . .
And you have already written the first three sentences of the full article: the world is filled with combinatorial problems .
these include important combinatorial optimization tasks such as planning , scheduling and rostering , combinatorics problems such as extremal graph theory , and countless puzzles and games .
solving combinatorial problems is hard , and all the methods we know to tackle them involve some kind of search ..
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various _ declarative paradigms _ have been developed to solve such problems . in such approaches , objects and attributes that are searched for
are represented by symbols , and constraints to be satisfied by those objects are represented as expressions over these symbols in a declarative language .
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11,956 |
Suppose that you have an abstract for a scientific paper: the electronic response of a two - dimensional ( 2d ) electron system represents a key quantity in discussing one - electron properties of electrons in semiconductor heterojunctions , on the surface of liquid helium and in copper - oxide planes of high - temperature superconductors .
we here report an evaluation of the wave - vector and frequency dependent dynamical quadratic density - response function of a 2d electron gas ( 2deg ) , within a self - consistent field approximation .
we use this result to find the @xmath0 correction to the stopping power of a 2deg for charged particles moving at a fixed distance from the plane of the 2d sheet , @xmath1 being the projectile charge .
we reproduce , in the high - density limit , previous full nonlinear calculations of the stopping power of a 2deg for slow antiprotons , and we go further to calculate the @xmath0 correction to the stopping power of a 2deg for a wide range of projectile velocities .
our results indicate that linear response calculations are , for all projectile velocities , less reliable in two dimensions than in three dimensions . .
And you have already written the first three sentences of the full article: since the pioneering work of bohm and pines@xcite , the conduction electrons in a metal have been described as a three - dimensional ( 3d ) gas of electrons in a neutralizing uniform positive charge . the dynamical linear density - response function of a 3d electron gas ( 3deg ) was evaluated by lindhard@xcite in the so - called random - phase approximation ( rpa ) , in which each electron is assumed to move in the external field plus the induced field of all electrons .
the wave - vector and frequency dependent dynamical quadratic density - response function of a 3deg has also been evaluated@xcite , by going beyond linear response theory .
the knowledge of this quantity has been proved to be of great importance in discussing the properties of electrons in a variety of 3d systems@xcite , and , in particular , in explaining the experimentally observed difference between the electronic energy losses of protons and antiprotons moving through a solid@xcite ..
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the suggested existence of two - dimensional electron layers in metal - insulator - semiconductor structures and on the surface of liquid helium led several years ago to a great activity in the study of a two - dimensional electron gas@xcite , where the electrons are confined to a plane and neutralized by an inert uniform rigid positive plane background .
the 2d electron system has also been considered in discussing the physics of new - class materials such as copper - oxide planes of high - temperature superconductors@xcite .
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11,957 |
Suppose that you have an abstract for a scientific paper: the first - generation stars in the @xmath0cdm universe are considered to have formed in dark halos with total masses in the range @xmath1 at @xmath2 . these stars expected to be very massive and
in some cases they end their lives as the first supernovae ( sne ) .
we explore the problem of whether star formation in low mass dark halos ( @xmath3 ) was triggered or suppressed by the sn feedback from neighboring star - forming halos .
we take into consideration mainly two effects by the sn shock : one is the evacuation of gas components from the halos and the other is the promotion of h@xmath4 formation because of the enhanced ionization degree by shock heating . combining above effects
, we find that the star formation activities in the neighboring dark matter halos ( @xmath5 ) are basically suppressed in case they are located close to the sn center , because of the gas evacuation effect .
the critical distance within which the gas is blown away falls within the range @xmath6kpc depending on the sn energy and the halo mass .
in addition , we find there is very little window in the parameter space where star formation activities in dark halos are induced or promoted by neighboring sn . .
And you have already written the first three sentences of the full article: star formation in the early universe has played a critical role in subsequent evolution of the universe .
first - generation stars may have substantially contributed to the cosmic reionization and metal pollution of the universe by their radiative / kinetic feedback effects .
these events are important for the formation and evolution of protogalaxies ..
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the studies of the initial collapse of primordial pre - galactic objects in the @xmath0cdm universe have been done in both analytical @xcite and numerical method @xcite .
these objects are formed with masses of the order of @xmath7 at redshifts @xmath8 .
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11,958 |
Suppose that you have an abstract for a scientific paper: we report on extensive photometry of dk lac obtained during the interval 1990 - 2009 , which includes a 2 mag low state during 2001 - 2003 .
much of the photometry consists of exposures obtained with a typical spacing of several days , but also includes 26 sequences of continuous photometry each lasting 2 to 7 hours .
we find no evidence for periodicities in our data .
we do find that the random variations in the low state are @xmath02@xmath1 those in the high state , when expressed in magnitudes .
the lack of orbital - time - scale variations is attributed to the nearly face - on presentation of the disk .
there is a 0.2 mag decline in the high state brightness of the system over 19 years , which is consistent with the behavior of other old novae in the decades following outburst .
high - state spectra are also presented and discussed .
we find that the equivalent width of h@xmath2 falls by @xmath02@xmath1 from 1991 to 2008 .
the photometric properties are discussed in the context of the hibernation scenario for the behavior of novae between outbursts , in which we conclude that low states in old novae are probably unrelated to their possible entrance into hibernation . .
And you have already written the first three sentences of the full article: dk lac was a moderately fast ( t@xmath3 = 32 d ) nova in 1950 , reaching v = 6 mag .
the nova light curve developed small eruptions midway down the decline ( e.g. ribbe 1951 ) , and the nebulae was spatially resolved ( barely ) by cohen ( 1985 ) and by slavin , obrien & dunlop ( 1995 ) ; otherwise dk lac has rather undistinguished nova properties ( duerbeck 1981 ) , and is not well - studied in its post - nova stage .
as far as we are aware there has not been an orbital period study ( spectroscopic or photometric ) for dk lac ..
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nova - like ( nl ) cataclysmic variables ( cvs ) sometimes fade by 1 - 4 magnitudes , remaining low from months to years ; these are known as vy scl stars .
the vy scl phenomenon is thought to be due to a cessation or diminution of the mass transfer from the secondary star to the white dwarf , temporarily robbing the system of its accretion luminosity . in 2001
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11,959 |
Suppose that you have an abstract for a scientific paper: doped zno is a promising material for spintronics applications . for such applications , it is important to understand the spin dynamics and particularly the spin relaxation times of this ii - vi semiconductor .
the spin relaxation time @xmath0 has been measured by optical orientation experiments , and it shows a surprising non - monotonic behavior with temperature . we explain this behavior by invoking spin exchange between localized and extended states .
interestingly , the effects of spin - orbit coupling are by no means negligible , in spite of the relatively small valence band splitting .
this is due to the wurtzite crystal structure of zno
. detailed analysis allows us to characterize the impurity binding energies and densities , showing that optical orientation experiments can be used as a characterization tool for semiconductor samples . .
And you have already written the first three sentences of the full article: zinc oxide has been the subject of considerable experimental and theoretical investigation for many years.@xcite its bandgap is in the near ultraviolet , making it useful as a transparent conductor and as sunscreen .
its piezoelectricity opens up transduction applications .
the activity has intensified more recently because of the possibility that zno might be useful for spintronics or spin - based quantum computation ..
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it has been predicted to be a room - temperature ferromagnet when doped with mn.@xcite furthermore , its spin - orbit coupling is generally thought to be very weak compared with gaas .
the usual measure of the strength of spin - orbit coupling in semiconductors is the energy splitting at the top of the valence band .
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11,960 |
Suppose that you have an abstract for a scientific paper: temperature - dependent inter - plane resistivity , @xmath0 , was measured systematically as a function of transition metal substitution in the iron - arsenide superconductors ba(fe@xmath1t@xmath2)@xmath3as@xmath3 , @xmath4= ni , pd , rh .
the data are compared with the behavior found in ba(fe@xmath1co@xmath2)@xmath3as@xmath3 , revealing resistive signatures of pseudogap . in all compounds we find resistivity crossover at a characteristic pseudogap temperature @xmath5 from non - metallic to metallic temperature dependence on cooling .
suppression of @xmath5 proceeds very similar in cases of ni and pd doping and much faster than in similar cases of co and rh doping . in cases of co and rh doping
an additional minimum in the temperature - dependent @xmath6 emerges for high dopings , when superconductivity is completely suppressed .
these features are consistent with the existence of a charge gap covering part of the fermi surface .
the part of the fermi surface affected by this gap is notably larger for ni and pd doped compositions than in co and rh doped compounds . .
And you have already written the first three sentences of the full article: pseudogap or partial gap in the electronic structure , affecting some regions of the fermi surface while leaving other unaffected , is one of the key signatures of the underdoped cuprates @xcite .
it is revealed through anomalous behaviors of the temperature - dependent resistivity , magnetization , nmr knight shift and relaxation rate , as well as in spectroscopic data @xcite .
pseudogap shows the same @xmath7-space distribution as the superconducting gap @xcite and is universally observed in hole- and electron- doped cuprates in the underdoped regime ..
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features consistent with pseudogap are also clearly found in hole doped feas - based materials ( see @xcite for a review ) . because the parent compounds of iron pnictides are metals ,
the pseudogap here is believed to arise from nesting instability @xcite . in ba(fe@xmath1t@xmath2)@xmath3as@xmath3 ( bat122 in the following)substitution of the transition metals into fe position
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11,961 |
Suppose that you have an abstract for a scientific paper: a new geiger mode avalanche photodiode , the micro pixel photon counter ( mppc ) , was recently released by hamamatsu .
it has a high photo - detection efficiency in the 420 nm spectral region .
this product can represent an elegant candidate for the design of a high granularity scintillator based hadron calorimeter for the international linear collider .
in fact , the direct readout of the blue scintillation photons with a mppc is a feasible techological solution .
the readout of a plastic scintillator by a mppc , both mediated by the traditional wavelength shifting fiber , and directly coupled , has been systematically studied .
desy 07 - 196 , , .
And you have already written the first three sentences of the full article: the prototype of the highly granular hadronic calorimeter for the international linear collider ( calice hcal @xcite ) consists of finely segmented arrays of scintillators .
each tile is read out by a geiger mode avalanche photodiode@xcite ( the sipm ) produced by mephi ( moscow engineering and physics institute ) , whose specific design matches the required performances needed for its application in the calorimeter @xcite . the small size ( 1 mm@xmath0 ) , high gain ( @xmath1 ) and relatively low bias voltage ( 30 - 70 v ) of the sipm made it the natural candidate for the high granularity calorimeter ; the photodetector could be directly installed in the tile . however , the sipm is a green sensitive photodetector ; the coupling with the blue emitting scintillator is obtained via a green wavelength shifting fibre , installed in a groove on the scintillator itself
. a simplification of this elementary structure would be highly desirable , in order to extend the concept to a large scale detector ..
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the new generation of geiger mode avalanche photodiodes , produced by hamamatsu , shows a better optical sensitivity in the 420 nm spectral region , making it possible to investigate the direct readout of the scintillation tile . in this
study the response to a minimum ionizing particle ( mip ) of a plastic organic scintillator read out by the most recent mppc@xcite , with both 400 and 1600 pixels , was analyzed .
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11,962 |
Suppose that you have an abstract for a scientific paper: the homomorphism problem for relational structures is an abstract way of formulating constraint satisfaction problems ( csp ) and various problems in database theory .
the decision version of the homomorphism problem received a lot of attention in literature ; in particular , the way the graph - theoretical structure of the variables and constraints influences the complexity of the problem is intensively studied .
here we study the problem of enumerating all the solutions with polynomial delay from a similar point of view .
it turns out that the enumeration problem behaves very differently from the decision version .
we give evidence that it is unlikely that a characterization result similar to the decision version can be obtained .
nevertheless , we show nontrivial cases where enumeration can be done with polynomial delay .
= = = = = = = = andrei a. bulatov vctor dalmau martin grohe dniel marx .
And you have already written the first three sentences of the full article: constraint satisfaction problems ( csp ) form a rich class of algorithmic problems with applications in many areas of computer science .
we only mention database systems , where csps appear in the guise of the conjunctive query containment problem and the closely related problem of evaluating conjunctive queries .
it has been observed by feder and vardi @xcite that as abstract problems , csps are homomorphism problems for relational structures ..
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algorithms for and the complexity of constraint satisfaction problems have been intensely studied ( e.g. @xcite ) , not only for the standard decision problems but also optimization versions ( e.g. @xcite ) and counting versions ( e.g. @xcite ) of csps . in this paper
we study the _ csp enumeration problem _ , that is , problem of computing all solutions for a given csp instance . more specifically , we are interested in the question which structural restrictions on csp instances guarantee tractable enumeration problems
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11,963 |
Suppose that you have an abstract for a scientific paper: we define jones s planar algebra as a map of multicategories and constuct a planar algebra starting from a @xmath0-cell in a pivotal strict @xmath1-category .
we prove finiteness results for the affine representations of finite depth planar algebras .
we also show that the radius of convergence of the dimension of an affine representation of the planar algebra associated to a finite depth subfactor is at least as big as the inverse - square of the modulus . .
And you have already written the first three sentences of the full article: in @xcite , vaughan jones introduced the notion of index for type @xmath2 subfactors . to any finite index subfactor @xmath3 one can associate a tower of @xmath4 factors @xmath5 .
the standard invariant of the subfactor is then given by the grid of finite dimensional algebras of relative commutants ( see @xcite , @xcite , @xcite , @xcite ) @xmath6 sorin popa in @xcite studied the question of which families @xmath7 of finite - dimensional @xmath8-algebras could arise as the tower of relative commutants of an extremal finite - index subfactor , that is , when does there exist such a subfactor @xmath9 such that @xmath10 .
he obtained a beautiful algebraic axiomatization of such families , which he called @xmath11__-lattices__. ocneanu gave a combinatorial description of the standard invariant as so called _ paragroups _ ( see @xcite ) ..
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subsequently , jones gave a geometric reformulation of the standard invariant , which he called _
planar algebras _
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11,964 |
Suppose that you have an abstract for a scientific paper: we present a first - principles computational scheme for investigating the ballistic transport properties of one - dimensional nanostructures with non - collinear magnetic order .
the electronic structure is obtained within density functional theory as implemented in the full - potential linearized augmented plane - wave ( flapw ) method and mapped to a tight - binding like transport hamiltonian via non - collinear wannier functions .
the conductance is then computed based on the landauer formula using the green s function method . as a first application we study the conductance between two ferromagnetic co monowires terminated by single mn apex atoms as a function of mn - mn separation .
we vary the mn - mn separation from the contact ( about @xmath0 to @xmath1 ) to the far tunneling regime ( @xmath1 to @xmath2 ) .
the magnetization direction of the co electrodes is chosen either in parallel or antiparallel alignment and we allow for different spin configurations of the two mn spins . in the tunneling and into the contact regime
the conductance is dominated by @xmath3-@xmath4-states . in the close contact regime ( below @xmath5 ) there is an additional contribution for a parallel magnetization alignment from the @xmath6- and @xmath7-states which give rise to an increase of the magnetoresistance as it is absent for antiparallel magnetization .
if we allow the mn spins to relax a non - collinear spin state is formed close to contact due to the competition of ferromagnetic coupling between mn and co and antiferromagnetic coupling between the mn spins .
we demonstrate that the transition from a collinear to such a non - collinear spin structure as the two mn atoms approach leaves a characteristic fingerprint in the distance - dependent conductance and magnetoresistance of the junction .
we explain the effect of the non - collinear spin state on the conductance based on the spin - dependent hybridization between the @xmath8-states of the mn spins and their coupling to the co electrodes . .
And you have already written the first three sentences of the full article: break junction experiments have allowed to perform transport studies on nanoscale metallic contacts in which the mean free path of the electrons is much larger than the junction length .
the observation of quantized conductance in such systems is a hallmark of ballistic transport and opened new vistas to study the scaling of electronic devices down to the atomic length scale.@xcite a drawback of such experiments is the limited control of the microscopic arrangement in the junction which hinders a straight forward interpretation of the data and makes a comparison with theoretical calculations difficult.@xcite in this respect , a great advantage is given by the use of scanning tunneling microscopy ( stm ) experiments , in which a tip can approach and contact single atoms or molecules on a surface.@xcite in such experiments , it has been possible to measure the conductance as a function of tip - sample distance from the tunneling to the contact regime . due to the promise of spintronic devices for future applications with low power consumption and high speed ,
a recent focus of such contact measurements has been magnetic systems , e.g. spin - valve behavior has been observed in single magnetic molecules or atoms on surfaces @xcite and the occurrence of the kondo effect has been found in ferromagnetic atomic contacts.@xcite it has been emphasized that the low coordination of the contact atoms in nanoscale junctions leads to an enhanced tendency towards magnetism , e.g. magnetic moments are formed in systems of otherwise non - magnetic materials.@xcite naturally , transport phenomena in such magnetic low - dimensional systems have raised a lot of attention and triggered many theoretical studies , which mainly focused on systems with collinear magnetic order , considering also the effect of magnetoresistance.@xcite it was also recently realized that , if the magnetization direction of the two electrodes is opposite , a domain wall can form in the contact between them and the non - collinear order in the....
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non - collinear spin alignment in such an atomic contact can also occur if the adatom spin is canted due to exchange coupling on a substrate with a spin spiral structure as in refs . and .
the effect of such a non - collinearity in the spin direction of the tip apex and the adatom on the conductance is the focus of the present work .
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11,965 |
Suppose that you have an abstract for a scientific paper: new data intensive applications , which are continuously emerging in daily routines of mobile devices , significantly increase the demand for data , and pose a challenge for current wireless networks due to scarce resources .
although bandwidth is traditionally considered as the primary scarce resource in wireless networks , the developments in communication theory shifts the focus from bandwidth to other scarce resources including processing power and energy .
especially , in device - to - device networks , where data rates are increasing rapidly , processing power and energy are becoming the primary bottlenecks of the network .
thus , it is crucial to develop new networking mechanisms by taking into account the processing power and energy as bottlenecks . in this paper
, we develop an energy - aware cooperative computation framework for mobile devices . in this setup , a group of cooperative mobile devices , within proximity of each other , ( i ) use their cellular or wi - fi ( 802.11 ) links as their primary networking interfaces , and ( ii ) exploit their device - to - device connections ( _ e.g. , _ wi - fi direct ) to overcome processing power and energy bottlenecks .
we evaluate our energy - aware cooperative computation framework on a testbed consisting of smartphones and tablets , and we show that it brings significant performance benefits . .
And you have already written the first three sentences of the full article: the dramatic increase in mobile applications and the number of devices demanding for wireless connectivity poses a challenge in today s wireless networks @xcite , and calls for new networking mechanisms .
one of the promising solutions to address the increasing data and connectivity demand is device - to - device ( d2d ) networking . as illustrated in fig .
[ fig : intro_example_new](a ) , the default operation in current wireless networks is to connect each device to the internet via its cellular or wi - fi interface . the d2d connectivity idea , which is illustrated in fig ..
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[ fig : intro_example_new](b ) , breaks this assumption : it advocates that two or more devices in close proximity can be directly connected , _
i.e. , _ without traversing through auxiliary devices such as a base station or access point .
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11,966 |
Suppose that you have an abstract for a scientific paper: we fit 54,296 sparsely - sampled asteroid lightcurves in the palomar transient factory ( ptf ) survey to a combined rotation plus phase - function model .
each lightcurve consists of 20 or more observations acquired in a single opposition . using 805 asteroids in our sample that have reference periods in the literature
, we find the reliability of our fitted periods is a complicated function of the period , amplitude , apparent magnitude and other lightcurve attributes . using the 805-asteroid ground - truth sample , we train an automated classifier to estimate ( along with manual inspection ) the validity of the remaining @xmath053,000 fitted periods . by this method
we find 9,033 of our lightcurves ( of @xmath08,300 unique asteroids ) have ` reliable ' periods .
subsequent consideration of asteroids with multiple lightcurve fits indicate a 4% contamination in these ` reliable ' periods . for 3,902 lightcurves with sufficient phase - angle coverage and either a reliably - fit period or low amplitude ,
we examine the distribution of several phase - function parameters , none of which are bimodal though all correlate with the bond albedo and with visible - band colors . comparing the theoretical maximal spin rate of a fluid body with our amplitude versus spin - rate distribution suggests that , if held together only by self - gravity , most asteroids are in general less dense than @xmath02 g/@xmath1 , while c types have a lower limit of between 1 and 2 g/@xmath1 .
these results are in agreement with previous density estimates . for 520 km
diameters , s types rotate faster and have lower amplitudes than c types
. if both populations share the same angular momentum , this may indicate the two types differing ability to deform under rotational stress .
lastly , we compare our absolute magnitudes ( and apparent - magnitude residuals ) to those of the minor planet center s nominal ( @xmath2 , rotation - neglecting ) model ; our phase - function plus fourier - series fitting reduces asteroid....
And you have already written the first three sentences of the full article: in this work we model an asteroid s apparent visual magnitude @xmath3 ( log flux ) as @xmath4,\ ] ] where @xmath5 is the absolute magnitude ( a constant ) , @xmath6 is a periodic variability term due to rotation ( _ e.g. _ , if the object is spinning and has some asymmetry in shape or albedo ) , @xmath7 and @xmath8 are the heliocentric and geocentric distances ( in au ) , and @xmath9 is the _ phase function _ , which varies with the solar phase angle @xmath10 ( the sun - asteroid - earth angle ) . when @xmath11 ( _ i.e. _ , at opposition ) , @xmath12 by definition , while in general @xmath13 for @xmath14 ( with @xmath15 decreasing as @xmath10 increases ) .
a key feature of our approach is the simultaneous fitting of both the phase function @xmath15 and the rotation term @xmath6 .
the detailed forms of @xmath15 and @xmath6 , as well as the algorithm underlying our fitting procedure , are motivated by a variety of prior work in this area , as described in the following sections ..
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building upon the work of @xcite , @xcite discuss the inversion of asteroid lightcurve data taken over several oppositions to obtain a 3d shape solution .
the form of @xmath6 ( cf .
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11,967 |
Suppose that you have an abstract for a scientific paper: recently , we developed a mean - field - type framework which treats the correlation induced by the tensor force . to exploit the tensor correlation we introduce single - particle states with the parity and charge mixing . to make a total wave function have a definite charge number and a good parity , the charge number and parity projections are performed .
taking a variation of the projected wave function with respect to single - particle states a hartree - fock - like equation , the charge- and parity - projected hartree - fock equation , is obtained . in the charge- and parity - projected hartree - fock method ,
we solve the equation selfconsistently .
in this paper we extend the charge- and parity - projected hartree - fock method to include a three - body force , which is important to reproduce the saturation property of nuclei in mean - field frameworks .
we apply the charge- and parity - projected hartree - fock method to sub - closed - shell oxygen isotopes ( @xmath0o , @xmath1o , @xmath2o , @xmath3o , and @xmath4o ) to study the effect of the tenor correlation and its dependence on neutron numbers .
we obtain reasonable binding energies and matter radii for these nuclei .
it is found that relatively large energy gains come from the tensor force in these isotopes and there is the blocking effect by occupied neutron orbits on the tensor correlation . .
And you have already written the first three sentences of the full article: the tensor force plays important roles in nuclear structure .
the study of nuclear matter using the brueckner theory showed that the tensor force is closely related to the binding mechanism and the saturation property of nuclear matter @xcite .
the almost exact calculations with very large model spaces exhibit a large attractive energy comes from the tensor force @xcite ..
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the tensor force is inferred to be responsible for about a half of the single - particle spin - orbit splitting in light nuclei @xcite . recently due to the development of experimental techniques , we can access to various kinds of unstable nuclei experimentally .
those experiments have been revealing that the shell structures of unstable nuclei may change from those of stable nuclei @xcite .
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11,968 |
Suppose that you have an abstract for a scientific paper: the recently developed massively parallel satisfiability ( sat ) solver hordesat was designed in a modular way to allow the integration of any sequential cdcl - based sat solver in its core .
we integrated the qcdcl - based quantified boolean formula ( qbf ) solver depqbf in hordesat to obtain a massively parallel qbf solver hordeqbf . in this paper
we describe the details of this integration and report on results of the experimental evaluation of hordeqbf s performance .
hordeqbf achieves superlinear average and median speedup on the hard application instances of the 2014 qbf gallery . .
And you have already written the first three sentences of the full article: hordesat @xcite is a modular massively parallel sat solver which allows the integration of any sequential cdcl - based sat solver in its core .
this enables the transfer of advancements in cdcl sat solving to a parallel setting .
experiments showed that hordesat can achieve superlinear average speedup on hard benchmarks ..
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the logic of quantified boolean formulas ( qbfs ) extends sat by explicit quantification of propositional variables .
problems in complexity classes beyond np , particularly pspace - complete problems in domains like , e.g. , formal verification , reactive synthesis , or planning , can naturally be encoded as qbfs .
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11,969 |
Suppose that you have an abstract for a scientific paper: it is sometimes stated that @xmath0 in hybrid inflation ; sometimes that it predicts @xmath1 . a number of authors have consider aspects of planck scale corrections and argued that they affect these predictions .
here we consider these systematically , describing the situations which can yield @xmath2 , and the extent to which this result requires additional tuning .
scipp 13/15 + 1.2 cm * small field inflation and the spectral index * 1.4 cm milton bose , michael dine , angelo monteux and laurel stephenson haskins + 0.4 cm _
santa cruz institute for particle physics and + department of physics , santa cruz ca 95064 _ + 1.5 cm 1.0 cm .
And you have already written the first three sentences of the full article: in @xcite , it was argued that , with some very mild assumptions about genericity , we can characterize small field inflation quite simply .
first , it was argued that the effective theory should exhibit an approximate ( global ) supersymmetry in order that there be fields light on the scale of the hubble constant during inflation , @xmath3 .
then , assuming @xmath4 : 1 ..
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the inflaton is a pseudomodulus , labeling a set of approximate ground states with spontaneously broken supersymmetry .
2 . the effective theory should obey a discrete @xmath5 symmetry in order that the cosmological constant ( c.c . )
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11,970 |
Suppose that you have an abstract for a scientific paper: classical chaotic systems with symbolic dynamics but strong pruning present a particular challenge for the application of semiclassical quantization methods . in the present study
we show that the technique of periodic orbit quantization by harmonic inversion of trace formulae , which does not rely on the existence of a complete symbolic dynamics or other specific properties , lends itself ideally to calculating semiclassical eigenvalues from periodic orbit data even in strongly pruned systems . as the number of periodic orbits proliferates exponentially in chaotic systems , we apply the harmonic inversion technique to cross - correlated periodic orbit sums , which allows us to reduce the required number of orbits .
the power of the method is demonstrated for the closed three - disk billiard as a prime example of a classically chaotic bound system with strong pruning . .
And you have already written the first three sentences of the full article: the relation between quantum spectra , on the one hand , and the dynamics of the corresponding classical systems , on the other , is a problem of fundamental importance in physics , which has attracted attention ever since the early days of quantum mechanics .
a key to understanding this relation in chaotic systems was gutzwiller s discovery ( cf .
@xcite ) that the semiclassical density of states in these systems can be written as a sum over all ( isolated ) periodic orbits of the classical system ..
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however , practical applications of gutzwiller s trace formula , like other periodic orbit sums , are greatly impeded by the fact that the sums usually diverge in the domain where the physical eigenvalues are located , mainly as a consequence of the rapid proliferation of periodic orbits with growing period .
various techniques were developed over the years to overcome the convergence problem of the periodic orbit sums @xcite , but most of them depend on special properties of the systems , such as ergodicity or the existence of complete symbolic dynamics . as an alternative
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11,971 |
Suppose that you have an abstract for a scientific paper: understanding neutrino interactions is an important task in searches for neutrino oscillations ; e.g. the @xmath0 oscillation hypothesis will be tested through @xmath1 production of @xmath2 in long - baseline experiments as well as underground neutrino telescopes .
an anomaly in the deep inelastic interaction of neutrinos has recently been observed by the nutev collaboration resulting in a measured weak mixing angle @xmath3 that differs by @xmath4 from the standard model expectation . in this contribution to the proceedings of nuint02 , we summarize results on the nlo neutrino structure functions and cross sections in which charm quark mass and target mass effects in the collinear approximation are included . .
And you have already written the first three sentences of the full article: the interpretation of the atmospheric muon neutrino deficit in the superkamiokande is that muon neutrinos oscillate to tau neutrinos with nearly maximal mixing @xcite .
experiments such as icanoe , opera and monolith will be able to test the oscillation hypothesis by searching for tau neutrino conversion to taus @xcite after the accelerator beam of muon neutrinos has passed over the long - baseline between cern and the gran sasso laboratory .
the minos experiment run at lower energies @xcite will look for the characteristic muon neutrino deficit . ultimately , one would like to know the neutrino - nucleon charged current cross section to the level of a few percent for precision measurements of oscillation mixing angles ..
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mass corrections , from both the out - going charged lepton and from the target nucleon , are important at this level . here , we report on lepton and target mass corrections in the collinear limit to neutrino - nucleon charged current interactions in deep inelastic scattering .
next - to - leading order qcd corrections and charm production are included .
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11,972 |
Suppose that you have an abstract for a scientific paper: we present a rigorous mathematical framework for analyzing dynamics of a broad class of boolean network models .
we use this framework to provide the first formal proof of many of the standard critical transition results in boolean network analysis , and offer analogous characterizations for novel classes of random boolean networks .
we precisely connect the short - run dynamic behavior of a boolean network to the average influence of the transfer functions .
we show that some of the assumptions traditionally made in the more common mean - field analysis of boolean networks do not hold in general .
for example , we offer some evidence that imbalance , or expected internal inhomogeneity , of transfer functions is a crucial feature that tends to drive quiescent behavior far more strongly than previously observed .
[ [ introduction . ] ] introduction .
+ + + + + + + + + + + + + complex systems can usually be represented as a network of interdependent functional units .
boolean networks were proposed by kauffman as models of genetic regulatory networks @xcite and have received considerable attention across several scientific disciplines .
they model a variety of complex phenomena , particularly in theoretical biology and physics @xcite .
a boolean network @xmath0 with @xmath1 nodes can be described by a directed graph @xmath2 and a set of _ transfer functions_. we use @xmath3 and @xmath4 to denote the sets of nodes and edges respectively , and denote the indegree of node @xmath5 by @xmath6 .
each node @xmath5 is assigned a @xmath6-ary boolean function @xmath7 , termed _
transfer function_. if the state of node @xmath5 at time @xmath8 is @xmath9 , its state at time @xmath10 is described by @xmath11 the state of @xmath0 at time @xmath8 is just the vector @xmath12 .
boolean networks are studied by positing a distribution of graph topologies and boolean functions from which independent random draws are made .
we denote the distribution of transfer functions by @xmath13 .
an....
And you have already written the first three sentences of the full article: we will be using probabilities very heavily , so it will help to set some notations .
capital letters @xmath139 will used to denote random variables .
events are denoted by calligraphic letters @xmath140 ..
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the probability of an event @xmath141 is denoted by @xmath142 .
the expectation of a random variable @xmath143 is denoted by @xmath144 $ ] .
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11,973 |
Suppose that you have an abstract for a scientific paper: we present high transverse momentum , @xmath0 , pion ( @xmath1 ) , proton ( @xmath2 ) , kaon ( @xmath3 ) , and rho ( @xmath4 ) spectra measured with the star experiment from p+p and au+au collisions with @xmath5 gev .
we find the @xmath6 ratio to be enhanced in au+au @xmath5 gev collisions relative to p+p @xmath5 gev collisions at @xmath7 gev / c .
the enhancement persists until @xmath8 gev / c for central au+au 200 gev collisions .
we also show the nuclear modification factor , @xmath9 , measured at the same center of mass energy , and find @xmath10 and @xmath11 to be higher than @xmath12 at @xmath13 gev / c .
implications for medium induced modifications of jet chemistry is discussed . .
And you have already written the first three sentences of the full article: collisions of relativistic heavy - ions aim to create a unique state of matter , where quarks and gluons can move over large volumes in comparison to the typical size of a hadron .
this state is known as the quark gluon plasma , qgp @xcite .
measurements of jet quenching have provided strong evidence such a state is created in heavy - ion collisions at the relativistic heavy ion collider , rhic @xcite ..
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these measurements show a suppression of hadron production at high-@xmath0 relative to p+p collisions , scaled by the number binary collisions , and the disappearance of correlated back to back hadron pairs in certain kinematic regions . how the chemistry within the jet is altered in heavy - ion collisions
may provide further information on the nature of jet quenching .
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11,974 |
Suppose that you have an abstract for a scientific paper: the behavior of the transition pion form factor for processes @xmath0 and @xmath1 at large values of space - like photon momenta is estimated within the nonlocal covariant quark - pion model .
it is shown that , in general , the coefficient of the leading asymptotic term depends dynamically on the ratio of the constituent quark mass and the average virtuality of quarks in the vacuum and kinematically on the ratio of photon virtualities .
the kinematic dependence of the transition form factor allows us to obtain the relation between the pion light - cone distribution amplitude and the quark - pion vertex function .
the dynamic dependence indicates that the transition form factor @xmath2 at high momentum transfers is very sensitive to the nonlocality size of nonperturbative fluctuations in the qcd vacuum .
keywords : nonperturbative calculations , pion form factors , nonlocal theories , and models .
And you have already written the first three sentences of the full article: the interest in the form factor @xmath3 for transition processes @xmath4 and @xmath5 , where @xmath6 and @xmath7 are photon momenta , has again increased recently . experimentally , the data on the form factor @xmath8 for small virtuality of one of the photons , @xmath9 , with the virtuality of the other photon being scanned up to @xmath10 gev@xmath11 , are known from cello @xcite and cleo @xcite collaborations .
theoretically , at zero virtualities , the form factor @xmath12 is related to the axial anomaly . at
asymptotically large photon virtualities , the behavior is predicted by perturbative qcd ( pqcd ) @xcite-@xcite ( see @xcite for recent discussions ) and depends crucially on the internal pion dynamics that is parametrized by the nonperturbative pion distribution amplitude ( da ) , @xmath13 , with @xmath14 being the fraction of the pion momentum , @xmath15 , carried by a quark ..
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moreover , the knowledge of the off - shell structure of the form factor enables one to significantly reduce the uncertainty in the evaluation of the hadronic light - by - light scattering contribution to the muon @xmath16
@xcite , which is relevant for the current experiment e821 at bnl @xcite . in the following ,
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11,975 |
Suppose that you have an abstract for a scientific paper: m85 optical transient 2006 - 1 ( m85ot2006 - 1 ) is the most luminous member of the small family of v838 mon - like objects , whose nature is still a mystery .
this event took place in the virgo cluster of galaxies and peaked at an absolute magnitude of @xmath0 . here
we present hubble space telescope images of m85ot2006 - 1 and its environment , taken before and after the eruption , along with a spectrum of the host galaxy at the transient location .
we find that the progenitor of m85ot2006 - 1 was not associated with any star forming region .
the @xmath1 and @xmath2-band absolute magnitudes of the progenitor were fainter than about @xmath3 and @xmath4 mag , respectively .
therefore , we can set a lower limit of @xmath5myr on the age of the youngest stars at the location of the progenitor that corresponds to a mass of @xmath6 m@xmath7 .
previously published line indices suggest that m85 has a mean stellar age of @xmath8 gyr .
if this mean age is representative of the progenitor of m85ot2006 - 1 , then we can further constrain its mass to be less than @xmath9 m@xmath7 .
we compare the energetics and mass limit derived for the m85ot2006 - 1 progenitor with those expected from a simple model of violent stellar mergers .
combined with further modeling , these new clues may ultimately reveal the true nature of these puzzling events . .
And you have already written the first three sentences of the full article: m85 optical transient 2006 - 1 ( m85ot2006 - 1 ; [email protected] ) was discovered on 2006 jan 6 by the lick observatory supernova search team ( filippenko et al .
2001bait / kait.html ] ) as a faint , @xmath11 mag transient in the galaxy m85 ( ngc4382 ) , which is at a distance of @xmath12 mpc ( mei et al . 2007 ) .
subsequent spectroscopy , as well as visible light and infra - red ( ir ) photometry , presented in kulkarni et al ..
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( 2007 ) , showed that m85ot2006 - 1 has a recession velocity of @xmath13 km s@xmath14 , and is therefore associated with m85 .
moreover , we showed that the temporal and spectral properties of this object are unlike those of supernovae , novae , or luminous blue variables .
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11,976 |
Suppose that you have an abstract for a scientific paper: with ( nonbarotropic ) equations of state valid even when the neutron , proton and electron content of neutron star cores is not in beta equilibrium , we study inertial and composition gravity modes of relativistic rotating neutron stars .
we solve the relativistic euler equations in the time domain with a three dimensional numerical code based on spectral methods , in the slow rotation , relativistic cowling and anelastic approximations .
principally , after a short description of the gravity modes due to smooth composition gradients , we focus our analysis on the question of how the inertial modes are affected by nonbarotropicity of the nuclear matter . in our study , the deviation with respect to barotropicity results from the frozen composition of nonsuperfluid matter composed of neutrons , protons and electrons , when beta equilibrium is broken by millisecond oscillations .
we show that already for moderately fast rotating stars the increasing coupling between polar and axial modes makes those two cases less different than for very slowly rotating stars .
in addition , as we directly solve the euler equations , without coupling only a few number of spherical harmonics , we always find , for the models that we use , a discrete spectrum for the @xmath0 inertial mode .
finally , we conclude that , for nonbarotropic stars , the frequency of this mode , which is our main focus , decreases in a non - negligible way , whereas the time dependence of the energy transfer between polar and axial modes is substantially different due to the existence of low - frequencies gravity modes .
* u * ps . * * ( ( ) ) .
And you have already written the first three sentences of the full article: since the result of andersson @xcite and friedman & morsink @xcite , numerous works have dealt with inertial modes of rotating relativistic stars ( see reviews by friedman & lockitch @xcite , andersson @xcite and kokkotas & ruoff @xcite ) . in perfect fluids ,
these modes have indeed been proven to satisfy the chandrasekhar - friedman - schutz ( cfs ; @xcite and @xcite ) criterion for instability whatever the angular velocity of the star is .
hence , due to their coupling to the gravitational field , these oscillations make neutron stars ( nss ) very promising sources of gravitational waves ( gw ) . yet , as nss are complex relativistic objects , far from perfect fluids , the astrophysical relevance of the instability of inertial modes in rotating nss is still an open issue ..
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the final answer to this question will depend on the many physical phenomena that take place within nss : their initial state at birth @xcite , existence of differential rotation @xcite , of a crust ( @xcite , @xcite , @xcite , @xcite ) , of a huge magnetic field @xcite , of superfluid states of nucleons ( @xcite , @xcite , @xcite ) , of exotic particles , _ etc_. understanding better that potential instability is important for two main reasons .
first , if it were proven to be relevant , it could have a great impact on our idea about the evolution of nss and might explain the relatively slow angular velocity of observed pulsars .
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11,977 |
Suppose that you have an abstract for a scientific paper: the longest common prefix array is a very advantageous data structure that , combined with the suffix array and the burrows - wheeler transform , allows to efficiently compute some combinatorial properties of a string useful in several applications , especially in biological contexts .
nowadays , the input data for many problems are big collections of strings , for instance the data coming from `` next - generation '' dna sequencing ( ngs ) technologies . in this paper
we present the first lightweight algorithm ( called ` extlcp ` ) for the simultaneous computation of the longest common prefix array and the burrows - wheeler transform of a very large collection of strings having any length .
the computation is realized by performing disk data accesses only via sequential scans , and the total disk space usage never needs more than twice the output size , excluding the disk space required for the input . moreover , ` extlcp ` allows to compute also the suffix array of the strings of the collection , without any other further data structure is needed .
finally , we test our algorithm on real data and compare our results with another tool capable to work in external memory on large collections of strings .
( # 1)`bwt`(#1 ) ( # 1)`c - ebwt`(#1 ) ( # 1)`bwt`(#1 ) # 1_#1 ( ) # 1_#1 ( ) # 1_#1 ( ) # 1_#1(w ) # 1_#1(w ) # 1(#1 ) .
And you have already written the first three sentences of the full article: the _ suffix array _ ( ) , the _ longest common prefix array _ ( ) and the _ burrows - wheeler transform _
( ) are data structures with many important applications in stringology @xcite .
the array of a string contains the lengths of the longest common prefixes of the suffixes pointed to by adjacent elements of the suffix array of the string @xcite ..
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the most immediate utility of the is to speed up suffix array algorithms and to simulate the more powerful , but more resource consuming , suffix tree .
indeed , the array , combined with or , simplifies the algorithms for some applications such as the rapid search for maximal exact matches , shortest unique substrings and shortest absent words @xcite .
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11,978 |
Suppose that you have an abstract for a scientific paper: this paper proposes a unifying variational approach for proving some fundamental information theoretic inequalities .
fundamental information theory results such as maximization of differential entropy , minimization of fisher information ( cramr - rao inequality ) , worst additive noise lemma , and extremal entropy inequality ( eei ) are interpreted as functional problems and proved within the framework of calculus of variations .
several applications and possible extensions of the proposed results are briefly mentioned .
maximizing entropy , minimizing fisher information , worst additive noise , extremal entropy inequality , calculus of variations .
And you have already written the first three sentences of the full article: the information theory realm , it is well - known that given the second - order moment ( or variance ) , a gaussian density function maximizes the differential entropy .
similarly , given the second - order moment , the gaussian density function minimizes the fisher information , a result which is referred to as the cramr - rao inequality in the signal processing literature .
surprisingly , the proofs proposed in the literature for these fundamental results are relatively quite diverse , and no unifying feature exists . since differential entropy or fisher information is a functional with respect to a probability density function , the most natural way to establish these results is by approaching them from the perspective of functional analysis ..
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this paper presents a unifying variational framework to address these results as well as numerous other fundamental information theoretic results .
a challenging information theoretic inequality , referred to as the extremal entropy inequality ( eei ) @xcite , can be dealt with successfully in the proposed framework of functionals .
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11,979 |
Suppose that you have an abstract for a scientific paper: a new method to solve dirac equation in 3d lattice is proposed , in which the variational collapse problem is avoided by inverse hamiltonian method and the fermion doubling problem is avoided by performing spatial derivatives in momentum space with the help of discrete fourier transform , i.e. , spectral method .
this method is demonstrated in solving the dirac equation for a given spherical potential in 3d lattice . in comparison with the results obtained by the shooting method , the differences in single particle energy are smaller than @xmath0 mev , and the densities are almost identical , which demonstrate the high accuracy of the present method . the results obtained by applying this method without any modification to solve the dirac equations for an axial deformed , non - axial deformed , octupole deformed potential are provided and discussed . .
And you have already written the first three sentences of the full article: the developments of new radioactive ion beam facilities and new detection techniques have largely extended our knowledge on nuclear physics from stable nuclei to unstable nuclei far from the @xmath1-stability line so - called exotic nuclei .
novel and striking features have been found in the nuclear structure of exotic nuclei , such as halo phenomenon @xcite and the disappearance of traditional magic numbers and occurrence of new ones @xcite . in order to describe the exotic nuclei with large space distribution , theoretical approaches
should be developed in coordinate space or coordinate - equivalent space ..
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density functional theory ( dft ) and its covariant version ( cdft ) have been proved to be effective theories for the description of exotic nuclei @xcite . in comparison with its nonrelativistic counterpart ,
the cdft has many attractive advantages , such as the natural inclusion of nucleon spin freedom , new saturation property of nuclear matter @xcite , large spin - orbit splittings in single particle energies , reproducing the isotopic shifts of pb isotopes @xcite , natural inclusion of time - odd mean field , explaining pseudospin of nucleon and spin symmetries of antinucleon in nuclei @xcite . in the cdft description for exotic nuclei , the dirac equation of the nucleons
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11,980 |
Suppose that you have an abstract for a scientific paper: this is the second paper of our investigation of the 0.5 - 2 kev soft x - ray luminosity function ( sxlf ) of active galactic nuclei ( agn ) using results from _ rosat _ surveys of various depth .
the large dynamic range of the combined sample , from shallow large - area _
rosat _ all - sky survey ( rass)-based samples to the satellite s deepest pointed observation on the lockman hole , enabled us to trace the behavior of the sxlf . while the first paper ( miyaji , hasinger , schmidt @xcite , hereafter paper i ) emphasized the global behavior of the sxlf , cosmological evolution and contribution to the soft x - ray background , this paper presents actual numerical values for practical use of our results . to present the binned sxlf ,
we have used an improved estimator , which is free from biases associated with the conventional @xmath0 estimator . .
And you have already written the first three sentences of the full article: the agn / qso luminosity function and its evolution with cosmic time are key observational quantities for understanding the origin of and accretion history onto supermassive black holes , which are now believed to occupy the centers of most galaxies .
since x - ray emission is one of the prominent characters of the agn activity , x - ray surveys are efficient means of sampling agns for luminosity function and evolution studies . an x - ray selected sample of agns is particularly useful because optical surveys often use point - like morphology as a criterion for selecting agns ( qsos ) among numerous other objects , and thus are likely to miss moderate - luminosity intermediate - high redshift agns embedded in their host galaxies .
also , radio surveys sample only a minor population of agns ..
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the _ rntgen satellite _ ( _ rosat _ ) provided us with soft x - ray surveys with various depths , ranging from the _ rosat _ all - sky survey ( rass , voges et al.@xcite ) to the _ rosat _ deep survey ( rds ) on the lockman hole ( hasinger et al .
various optical identification programs of the survey fields have been conducted and the combination of these now enabled us to construct the soft x - ray luminosity function ( sxlf ) as a function of redshift . in paper i. , we presented a number of global representations of the 0.5 - 2 kev sxlf and investigated the contribution to the soft x - ray background .
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11,981 |
Suppose that you have an abstract for a scientific paper: a simple and computationally efficient parameterization of the deleptonization , the entropy changes , and the neutrino stress is presented for numerical simulations of stellar core collapse . the parameterization of the neutrino physics is based on a bounce profile of the electron fraction as it results from state - of - the - art collapse simulations with multi - group boltzmann neutrino transport in spherical symmetry .
two additional parameters include an average neutrino escape energy and a neutrino trapping density .
the parameterized simulations reproduce the consequences of the delicate neutrino thermalization / diffusion process during the collapse phase and provide a by far more realistic alternative to the adiabatic approximation , which has often been used in the investigation of the emission of gravitational waves , of multidimensional general relativistic effects , of the evolution of magnetic fields , or even of the nucleosynthesis in simulations of core collapse and bounce . for supernova codes that are specifically designed for the postbounce phase , the parameterization builds a convenient bridge between the point where the applicability of a stellar evolution code ends and the point where the postbounce evolution begins . .
And you have already written the first three sentences of the full article: since the mid sixties , the gravitational collapse of stars has been studied based on computer simulations @xcite . investigated topics in the collapse phase included general relativistic dynamics @xcite , magnetic fields @xcite , deleptonization and neutrino trapping @xcite , progenitor rotation @xcite , dissociation energy @xcite , neutrino transport and thermalization @xcite , nuclear electron capture @xcite , and the emission of gravitational waves @xcite , to name only a few of the many possible references .
later , the field has somewhat separated into two rather disjunct lines of research . on the one hand ,
the increasing computing power was focused on the details of the neutrino physics and neutrino transport in spherical symmetry . on the other hand ,.
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the computational resources were invested in multidimensional dynamics for the investigation of rotating progenitors @xcite , general relativity @xcite , and magnetic fields @xcite .
only few recent multidimensional collapse simulations made the effort to include neutrino physics .
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11,982 |
Suppose that you have an abstract for a scientific paper: we reformulate the strong - interaction limit of electronic density functional theory in terms of a classical problem with a degenerate minimum .
this allows us to clarify many aspects of this limit , and to write a general solution , which is explicitly calculated for spherical densities .
we then compare our results with previous approximate solutions and discuss the implications for density functional theory . .
And you have already written the first three sentences of the full article: density functional theory @xcite ( dft ) is by now the most popular method for electronic structure calculations in condensed matter physics and quantum chemistry , because of its unique combination of low computational cost and reasonable accuracy for many molecules and solids . in applying dft to a given electron system , the only quantity that must be approximated in practice
is the functional @xmath0 $ ] for the exchange - correlation energy .
an exact expression for this functional is the coupling - constant integral , e=_0 ^ 1 dw _ [ ] . [ cci ] the integrand.
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is defined as w_[]= _ [ ] ||_[]-u [ ] .
[ walpha ] here , @xmath1=\frac12\int
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11,983 |
Suppose that you have an abstract for a scientific paper: highly condensed gaseous objects with masses larger than are called _ super - massive stars_. they are thought to be possible precursors of super - massive black holes in the centres of galaxies . in the quasistationary contraction phase , the hydrostatic equilibrium is determined by radiation pressure and gravitation .
the global structure is that of an @xmath0 polytrope at the stability limit .
small relativistic corrections for example can initiate a free fall collapse due to the post newtonian instability . since the outcome of the final collapse a super - massive black hole or hypernova depends sensitively on the structure and the size of the object ,
when the instability sets in , it is important to investigate in more detail the contraction phase of the sms .
if the gaseous object is embedded in a dense stellar system , the central star cluster , the interaction and coupling of both components due to dynamical friction changes the energy balance and evolution of the sms dramatically . dynamical friction between stars and gas , which can be estimated semi - analytically ( see just @xcite ) , has three different effects on the two - component system : 1 ) the gas is heated by decelerating the stars .
this may stall the contraction process for a while until the stars in the loss cone , these which cross the sms , lost their kinetic energy ( for the total heating rate see amaro - seoane & spurzem @xcite ) .
2 ) this cooling of the loss cone stars lead to a mass segregation in the stellar component resulting in a much more condensed central stellar core .
3 ) the inhomogeneities due to the gravitational wakes in the gas changes the effective absorption coefficient of the gas . this affects the condition for hydrostatic equilibrium and may give essential deviations from the @xmath0 polytrope .
we discuss in which evolutionary stages and parameter range these interaction processes are relevant and how they can influence the stability and evolution of the sms . .
And you have already written the first three sentences of the full article: in the standard picture of galactic structure , most galaxies harbour a central super - massive black hole ( smbh ) , which is quiet in normal galaxies and responsible for quasar and seyfert activities in active galaxies .
but the building process of smbhs is still not fully understood .
is the way of creating a smbh with more than @xmath1 a direct collapse of a gas cloud , is it the growth of a small seed black hole in a dense star cluster , or is it the remnant of a hypernova of a super massive star like object ( sms ) ? in the building process of a smbh two basic paths can be distinguished ( rees @xcite ) . at the stellar dynamical path.
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the gas cloud initially forms a massive central star cluster or bulge .
stellar and dynamical evolution including star - star collisions than form a seed black hole with initial mass up to @xmath2 .
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11,984 |
Suppose that you have an abstract for a scientific paper: for homogeneous higher gradient elasticity models we discuss frame - indifference and isotropy requirements . to this end , we introduce the notions of local versus global so(3)-invariance and identify frame - indifference ( traditionally ) with global left so(3)-invariance and isotropy with global right so(3)-invariance
. for specific restricted representations , the energy may also be local left so(3)-invariant as well as local right so(3)-invariant .
then we turn to linear models and consider a consequence of frame - indifference together with isotropy in nonlinear elasticity and apply this joint invariance condition to some specific linear models .
the interesting point is the appearance of finite rotations in transformations of a geometrically linear model .
it is shown that when starting with a linear model defined already in the infinitesimal symmetric strain @xmath0}$ ] , the new invariance condition is equivalent to isotropy of the linear formulation . therefore , it may be used also in higher gradient elasticity models for a simple check of isotropy and for extensions to anisotropy . in this respect
we consider in more detail variational formulations of the linear indeterminate couple stress model , a new variant of it with symmetric force stresses and general linear gradient elasticity .
+ + * key words : * invariance conditions , frame - indifference , covariance , isotropy , orthogonal group , strain gradient elasticity , couple stress , polar continua , symmetric stress , hyperstresses , modified couple stress model , rotational invariance , form - invariance , rayleigh product + ams math 74a10 ( stress ) , 74a35 ( polar materials ) , 74b05 ( classical linear elasticity ) , 74a30 ( nonsimple materials ) , 74a20 ( theory of constitutive functions ) , 74b20 ( nonlinear elasticity ) .
And you have already written the first three sentences of the full article: this paper is motivated by our endeavour to better understand isotropy conditions in higher gradient elasticity theories .
therefore , we make use of the old idea expressed by truesdell ( * ? ? ?
* lecture 6 ) albeit including higher gradient continua ..
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rotations can not be detected by any experiment .
the response of the material with respect to the reference configuration @xmath1 is the same as that with respect to any other obtained from it by rotation . '' ] to this end we reconsider frame - indifference and isotropy first in nonlinear elasticity and then in classical linear elasticity theories .
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11,985 |
Suppose that you have an abstract for a scientific paper: we study the action of the elements of the mapping class group of a surface of finite type on the teichmller space of that surface equipped with thurston s asymmetric metric .
we classify such actions as elliptic , parabolic , hyperbolic and pseudo - hyperbolic , depending on whether the translation distance of such an element is zero or positive and whether the value of this translation distance is attained or not , and we relate these four types to thurston s classification of mapping classes .
the study is parallel to the one made by bers in the setting of teichmller space equipped with teichmller s metric , and to the one made by daskalopoulos and wentworth in the setting of teichmller space equipped with the weil - petersson metric .
ams mathematics subject classification : 32g15 ; 30f60 ; 57m50 ; 57n05 .
keywords : teichmller space ; thurston s asymmetric metric ; mapping class group . .
And you have already written the first three sentences of the full article: let @xmath0 be a connected oriented surface of finite type , of genus @xmath1 with @xmath2 punctures .
we assume that the euler characteristic of @xmath3 is negative .
we shall consider hyperbolic structures on @xmath3 and any such structure will be complete and of finite area ..
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we say that two complex structures ( respectively hyperbolic structures ) @xmath4 and @xmath5 on @xmath3 are equivalent if there is a conformal map ( respectively an isometry ) from @xmath4 to @xmath5 which is homotopic to the identity map of @xmath3 .
the teichmller space @xmath6 of @xmath3 is the space of complex structures ( or , equivalently , the space of hyperbolic structures ) on @xmath3 up to equivalence .
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11,986 |
Suppose that you have an abstract for a scientific paper: we present here simultaneous integral / rxte observations of sco x-1 , and in particular a study of the hard x - ray emission of the source and its correlation with the position in the z - track of the x - ray color - color diagram . we find that the hard x - ray ( above about 30 kev ) emission of sco x-1 is dominated by a power - law component with a photon index of @xmath0 .
the flux in the power - law component slightly decreases when the source moves in the color - color diagram in the sense of increasing inferred mass accretion rate from the horizontal branch to the normal branch / flaring branch vertex .
it becomes not significantly detectable in the flaring branch , where its flux has decreased by about an order of magnitude .
these results present close analogies to the behavior of gx 17 + 2 , one of so - called sco - like z sources .
finally , the hard power law in the spectrum of sco x-1 does not show any evidence of a high energy cutoff up to @xmath1 kev , strongly suggesting a non - thermal origin of this component . .
And you have already written the first three sentences of the full article: hard x - ray emission in the brightest low - mass x - ray binaries ( hereafter lmxbs ) , the so - called z - sources , was occasionally detected in the past ( see e.g. peterson & jacobson 1966 ) .
these results received relatively little attention , mostly because the lack of a broad - band spectral coverage did not permit to establish whether an extra component was indeed required to fit the hard spectrum of these sources .
renewed interest in the hard x - ray emission properties of bright lmxbs was motivated by recent broad - band studies mainly performed with rxte ( 2 200 kev ) and bepposax ( 0.1 200 kev ) ..
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these have shown that most z - sources display variable , hard power - law shaped components , dominating their spectra above @xmath2 kev ( see di salvo & stella 2000 for a review ) .
the hard component detected in bright ( otherwise soft ) lmxbs can be fitted by a power law , with photon index in the range 1.93.3 , contributing from 1% to 10% of the observed ( @xmath3 kev ) source luminosity .
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11,987 |
Suppose that you have an abstract for a scientific paper: three - dimensional @xmath0 lattice gauge theories at zero temperature are studied for various values of @xmath1 . using a modified phenomenological renormalization group
, we explore the critical behavior of the generalized @xmath0 model for @xmath2 .
numerical computations are used to simulate vector models for @xmath3 for lattices with linear extension up to @xmath4 .
we locate the critical points of phase transitions and establish their scaling with @xmath1 .
the values of the critical indices indicate that the models with @xmath5 belong to the universality class of the three - dimensional @xmath6 model .
however , the exponent @xmath7 derived from the heat capacity is consistent with the ising universality class .
we discuss a possible resolution of this puzzle .
we also demonstrate the existence of a rotationally symmetric region within the ordered phase for all @xmath8 at least in the finite volume .
* critical behavior of @xmath9 @xmath0 lattice gauge theories at zero temperature * 0.3 cm o. borisenko@xmath10 , v. chelnokov@xmath11 , g. cortese@xmath12 , m. gravina@xmath13 , a. papa@xmath14 , i. surzhikov@xmath15 0.6 cm @xmath16 _ bogolyubov institute for theoretical physics , _ _ national academy of sciences of ukraine , _ _ 03680 kiev , ukraine _
0.2 cm @xmath17 _ instituto de fsica terica uam / csic , _
_ cantoblanco , e-28049 madrid , spain _ _ and departamento de fsica terica , _ _ universidad de zaragoza , e-50009 zaragoza , spain _ 0.2 cm @xmath18 _ dipartimento di fisica , universit della calabria , _ _ and istituto nazionale di fisica nucleare , gruppo collegato di cosenza _
_ i-87036 arcavacata di rende , cosenza , italy _ 0.6 cm ' '' '' : @[email protected] , @[email protected] , @[email protected] , @[email protected] , @[email protected] , @[email protected] .
And you have already written the first three sentences of the full article: models possessing global and/or local discrete @xmath0 symmetry play an important role in many branches of physics ranging from the solid state physics to the description of the universality features of the deconfining transition in @xmath25 gauge theories . in this paper
we are interested in the @xmath0 lattice gauge theory ( lgt ) at zero temperature . assigning the gauge fields @xmath26 to the links of a simple hypercubic lattice ,
the most general action of the isotropic @xmath0 lgt can be written as @xmath27 where @xmath28 , @xmath29 , denotes the unit vector in the @xmath30-th direction ..
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similarly , the most general action of the @xmath0 spin model is given by @xmath31 in both cases we used the convention @xmath32 the standard potts model corresponds to the choice when all @xmath33 are equal .
then , the sum over @xmath34 reduces to a delta - function on the @xmath0 group .
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11,988 |
Suppose that you have an abstract for a scientific paper: we construct rank 2 thick nondiscrete affine buildings associated with an arbitrary finite dihedral group . .
And you have already written the first three sentences of the full article: in his foundational work on buildings , j.tits @xcite proved that all thick irreducible spherical and affine buildings of rank @xmath0 ( including nondiscrete ones ) are associated with algebraic groups and , hence , have weyl groups coming from root systems .
he then showed @xcite how to use the _ free construction _ to prove existence of thick spherical buildings of rank 2 modeled on arbitrary finite coxeter groups ( see definition [ modeled ] ) .
such buildings are necessarily infinite except for dihedral groups of the order @xmath1 ..
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m.ronan @xcite constructed a variety of irreducible rank 2 discrete affine buildings not coming from algebraic groups .
the corresponding finite coxeter groups are necessarily of crystallographic type , i.e. , they are the dihedral groups @xmath2 .
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11,989 |
Suppose that you have an abstract for a scientific paper: the steadily improving sensitivity of pulsar timing arrays ( ptas ) suggests that gravitational waves ( gws ) from supermassive black hole binary ( smbhb ) systems in the nearby universe will be detectable sometime during the next decade .
currently , ptas assume an equal probability of detection from every sky position , but as evidence grows for a non - isotropic distribution of sources , is there a most likely sky position for a detectable single source of gws ? in this paper , a collection of galactic catalogs is used to calculate various metrics related to the detectability of a single gw source resolvable above a gw background , assuming that every galaxy has the same probability of containing a smbhb .
our analyses of these data reveal small probabilities that one of these sources is currently in the pta band , but as sensitivity is improved regions of consistent probability density are found in predictable locations , specifically around local galaxy clusters . .
And you have already written the first three sentences of the full article: pulsar timing arrays ( ptas ) are collections of millisecond pulsars @xcite whose joint timings will show correlations that are a specific signature of gravitational waves ( gws ) passing between the earth and the pulsars @xcite . currently , there are three ptas working collaboratively to detect gws in this way @xcite
. these arrays will soon have the sensitivity to detect single extragalactic sources of gws , @xcite which are resolvable above a gw background @xcite . to increase the efficiency of pta observations and
potentially decrease the time until a detection is made , various groups have considered the optimization of pta observations @xcite , but all have assumed an equal probability of detection across the sky . while all directions are equally likely to contain a gw source , there should exist more probable locations for the brightest gw source . and.
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while the probability is quite small for there to exist a source that stands out above the background , the analysis in this paper identifies the potential locations of that source using what is currently known about the distribution of galaxies in the local universe , and allows others to enhance discussions on the optimization of a pta @xcite .
supermassive black hole binary ( smbhb ) systems with periods of months to years are thought to be the most important source of gravitational waves @xcite .
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11,990 |
Suppose that you have an abstract for a scientific paper: using non - equilibrium green s functions , we studied numerically the transport properties of a josephson junction , superconductor - topological insulator - superconductor hybrid system .
our numerical calculation shows first that proximity - induced superconductivity is indeed observed in the edge states of a topological insulator adjoining two superconducting leads and second that the special characteristics of topological insulators endow the edge states with an enhanced proximity effect with a superconductor but do not forbid the bulk states to do the same . in a size - dependent analysis of the local current
, it was found that a few residual bulk states can lead to measurable resistance , whereas because these bulk states spread over the whole sample , their contribution to the interference pattern is insignificant when the sample size is in the micrometer range .
based on these numerical results , it is concluded that the apparent disappearance of residual bulk states in the superconducting interference process as described in ref .
[ ] is just due to the effects of size : the contribution of the topological edge states outweighs that of the residual bulk states . .
And you have already written the first three sentences of the full article: since the original theoretical proposals@xcite of the existence of topological insulators ( tis ) and their eventual realization in hgte / cdte and inas / gasb quantum wells ( qws),@xcite extensive studies of their properties have been performed .
because of the topological non - triviality of topological insulators , it was expected that the dissipationless current carried by topologically protected edge states could be utilized to construct electronic devices with low power consumption .
experimentally , however , the edge states that were expected to be robust were found to become unstable when the sample of hgte / cdte quantum wells became somewhat larger and reached sizes of a few microns ..
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this experimental finding stirred up a lot of interest .
how disorder , magnetic impurity , electron - electron interaction , electron - phonon interaction , etc , and the various combinations of these effects , could affect transport in edge states as well as the topological properties of tis themselves have been intensively studied.@xcite the notion that topological superconductors ( tss ) , similar to tis , possess topologically protected gapless edge or surface states traversing through the superconductor gap , was also put forward .
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11,991 |
Suppose that you have an abstract for a scientific paper: a distinct sub - class of anomalous velocity emission features has emerged from recent high quality surveys of the local group environment , namely the compact high velocity clouds ( chvcs ) .
a program of high - resolution imaging with the westerbork array and the arecibo telescope has begun to provide many insights into the nature of these objects .
elongated core components with a velocity gradient consistent with rotation ( v@xmath0 15 ) are seen in many objects .
comparison of volume and column densities has allowed the first distance estimates to be made ( 600@xmath1300 kpc ) .
the objects appear to be strongly dark - matter dominated with dark - to - gas mass ratios of 3050 implied if the typical distance is 700 kpc .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: the nature of anomalous velocity discovered during @xmath221 cm surveys of the galaxy has been the subject of much debate in the past three decades .
there appear to be at least four reasonably distinct classes of this gas , namely : ( 1 ) localized outflows and subsequent inflows associated with massive star formation which are commonly referred to as a `` galactic fountain '' ( shapiro & field , 1976 ; bregman , 1980 ) .
( 2 ) the stream of tidal debris from the interaction of the galaxy with the magellanic clouds is another major source of anomalous velocity ..
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recent imaging ( putman & gibson , 1999 ) has begun to reveal the true extent of this debris system , and allow it to be distinguished from other components .
( 3 ) the extended hvc complexes ( named a , c , h , m , ) which span ten s of degrees on the sky and have recently been determined to have both nearby distances of about 10 kpc ( van woerden et al .
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11,992 |
Suppose that you have an abstract for a scientific paper: we celebrate two birthdays connected with the radiation zero phenomenon .
first , a striking dip in the theoretical angular distributions of radiative weak - boson production was discovered twenty years ago .
the key experimental interest is that this will not occur in any deviation from the standard model .
second , the classical training of stanley brodsky began sixty years ago , which was instrumental in understanding why theoretical spin - independent radiation zeros appear in almost all born amplitudes for the radiation of photons and gluons and other massless gauge bosons ( but rarely in physical kinematic regions ) . and there are approximate zeros for massive bosons and `` type ii '' zeros that can also be studied .
we discuss how the difficulties in observing the original mikaelian - samuel - sahdev zero finally may be surmounted next year . .
And you have already written the first three sentences of the full article: the first radiation zeros were discovered as a consequence of a general investigation @xcite of the production of electroweak pairs in hadronic collisions @xmath0 and neutrino reactions @xmath1 addressed to very - high - energy cosmic - ray physics .
the investigation probed the sensitivity of these reactions to the trilinear gauge boson couplings and , at the present time , useful limits on their deviations from gauge theory predictions have been obtained in @xmath2 and hadron collider experiments @xcite .
pronounced dips were found @xcite in the angular distributions for the production of @xmath3 and @xmath4 in the two - body parton and lepton reactions ..
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subsequent work @xcite by mikaelian , samuel , and sahdev proved that the @xmath3 dips were in fact exact zeros at particular angles , which would be ruined by non - gauge couplings .
the wisconsin brain trust @xcite followed with a general demonstration of the implied amplitude factorization .
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11,993 |
Suppose that you have an abstract for a scientific paper: hydrophobic thickness mismatch between integral membrane proteins and the surrounding lipid bilayer can produce lipid bilayer thickness deformations .
experiment and theory have shown that protein - induced lipid bilayer thickness deformations can yield energetically favorable bilayer - mediated interactions between integral membrane proteins , and large - scale organization of integral membrane proteins into protein clusters in cell membranes . within the continuum elasticity theory of membranes , the energy cost of protein - induced bilayer
thickness deformations can be captured by considering compression and expansion of the bilayer hydrophobic core , membrane tension , and bilayer bending , resulting in biharmonic equilibrium equations describing the shape of lipid bilayers for a given set of bilayer - protein boundary conditions . here
we develop a combined analytic and numerical methodology for the solution of the equilibrium elastic equations associated with protein - induced lipid bilayer deformations .
our methodology allows accurate prediction of thickness - mediated protein interactions for arbitrary protein symmetries at arbitrary protein separations and relative orientations .
we provide exact analytic solutions for cylindrical integral membrane proteins with constant and varying hydrophobic thickness , and develop perturbative analytic solutions for non - cylindrical protein shapes .
we complement these analytic solutions , and assess their accuracy , by developing both finite element and finite difference numerical solution schemes .
we provide error estimates of our numerical solution schemes and systematically assess their convergence properties . taken together
, the work presented here puts into place an analytic and numerical framework which allows calculation of bilayer - mediated elastic interactions between integral membrane proteins for the complicated protein shapes suggested by structural biology and at the small protein separations most relevant for the crowded....
And you have already written the first three sentences of the full article: in many cell types , cell membranes are composed @xcite of a diverse array of lipids , organized as a lipid bilayer , and membrane proteins , which play a central role in most cellular processes .
membrane proteins are rigid compared to the surrounding lipid bilayer @xcite .
thus , the lipid bilayer typically deforms to accommodate membrane proteins and , in particular , the bilayer hydrophobic thickness is compressed or expanded compared to the preferred bilayer thickness in the absence of membrane proteins @xcite ..
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distinct conformations of a membrane protein generally yield distinct energy costs of protein - induced lipid bilayer deformations . as a result ,
the lipid bilayer can serve as a `` splint '' stabilizing certain protein conformations @xcite and thereby regulate protein function @xcite . in agreement with this general picture ,
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11,994 |
Suppose that you have an abstract for a scientific paper: data subject to heavy - tailed errors are commonly encountered in various scientific fields , especially in the modern era with explosion of massive data . to address this problem ,
procedures based on quantile regression and least absolute deviation ( lad ) regression have been developed in recent years .
these methods essentially estimate the conditional median ( or quantile ) function
. they can be very different from the conditional mean functions when distributions are asymmetric and heteroscedastic .
how can we efficiently estimate the mean regression functions in ultra - high dimensional setting with existence of only the second moment ? to solve this problem , we propose a penalized huber loss with diverging parameter to reduce biases created by the traditional huber loss .
such a penalized robust approximate quadratic ( ra - quadratic ) loss will be called ra - lasso . in the ultra - high dimensional
setting , where the dimensionality can grow exponentially with the sample size , our results reveal that the ra - lasso estimator produces a consistent estimator at the same rate as the optimal rate under the light - tail situation .
we further study the computational convergence of ra - lasso and show that the composite gradient descent algorithm indeed produces a solution that admits the same optimal rate after sufficient iterations . as a byproduct
, we also establish the concentration inequality for estimating population mean when there exists only the second moment .
we compare ra - lasso with other regularized robust estimators based on quantile regression and lad regression .
extensive simulation studies demonstrate the satisfactory finite - sample performance of ra - lasso . _
key words _ : high dimension , huber loss , m - estimator , optimal rate , robust regularization . .
And you have already written the first three sentences of the full article: our era has witnessed the massive explosion of data and a dramatic improvement of technology in collecting and processing large data sets .
we often encounter huge data sets that the number of features greatly surpasses the number of observations .
it makes many traditional statistical analysis tools infeasible and poses great challenge on developing new tools ..
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regularization methods have been widely used for the analysis of high - dimensional data .
these methods penalize the least squares or the likelihood function with the @xmath0-penalty on the unknown parameters ( lasso , @xcite ) , or a folded concave penalty function such as the scad @xcite and the mcp@xcite .
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11,995 |
Suppose that you have an abstract for a scientific paper: two families of symplectic methods specially designed for second - order time - dependent linear systems are presented .
both are obtained from the magnus expansion of the corresponding first - order equation , but otherwise they differ in significant aspects .
the first family is addressed to problems with low to moderate dimension , whereas the second is more appropriate when the dimension is large , in particular when the system corresponds to a linear wave equation previously discretised in space .
several numerical experiments illustrate the main features of the new schemes .
second - order linear differential equations ; non - autonomous ; symplectic integrators ; magnus expansion ; matrix hill s equation 65l07 ; 65l05 ; 65z05 .
And you have already written the first three sentences of the full article: the problem we address in this paper is the numerical integration of the second order time - dependent linear equation @xmath0 where @xmath1 , @xmath2 and primes denote time - derivatives .
it has many practical applications , for example , in periodically variable systems such as quadrupole mass filter and quadrupole devices , @xcite , microelectromechanical systems @xcite , in bose
einstein condensates , spatially linear electric fields , dynamic buckling of structures , electrons in crystal lattices , waves in periodic media , etc ..
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( see @xcite and references therein ) . in these cases
the matrix @xmath3 is usually time periodic with period @xmath4 ( ( [ hill ] ) is then an example of a matrix hill equation ) and of moderately large size @xmath5 .
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11,996 |
Suppose that you have an abstract for a scientific paper: we propose to measure the @xmath0 phase @xmath1 , the magnitude of the neutrino mixing matrix element @xmath2 and the sign of the atmopheric scale mass squared difference @xmath3 with a superbeam by the joint analysis of two different long baseline neutrino oscillation experiments .
one is a long baseline experiment ( lbl ) at 300 km and the other is a very long baseline ( vlbl ) experiment at 2100 km .
we take the neutrino source to be the approved high intensity proton synchrotron , hipa .
the neutrino beam for the lbl is the 2-degree off - axis superbeam and for the vlbl , a narrow band superbeam .
taking into account all possible errors , we evaluate the event rates required and the sensitivities that can be attained for the determination of @xmath1 and the sign of @xmath4 .
we arrive at a representative scenario for a reasonably precise probe of this part of the neutrino physics .
= # 1,nucl . phys .
b * # 1 * , # 1,phys .
lett .
b * # 1 * , # 1,phys .
rev .
d * # 1 * , # 1,phys .
rev .
lett . *
# 1 * , # 1,z .
phys .
c * # 1 * , * measuring @xmath0 violation and mass ordering in + joint long baseline experiments with superbeams * + k. whisnant@xmath5 , jin min yang@xmath6 , bing - lin young@xmath5 + _ @xmath5 department of physics and astronomy , iowa state university , ames , iowa 50011 , usa + @xmath6 institute of theoretical physics , academia sinica , beijing 100080 , china _ .
And you have already written the first three sentences of the full article: the super - kamiokande experiments @xcite in the past several years , joined by sno @xcite more recently , have given strong indications of neutrino oscillation that are corroborated and constrained by a variety of other experiments .
these experiments started a new era in the study of neutrino physics and offered the best indication to date of physics beyond the standard model . to further probe neutrino physics , there are a number of ongoing and planned neutrino oscillation experiments .
these experiments promise to give a full description of the phenomenology of neutrino mixing ..
Please generate the next two sentences of the article
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the most attractive experiments among the new generation of neutrino oscillation experiments are the long baseline ( lbl ) experiments .
they are performed in the controlled environment of traditional experimental high energy physics and expected to allow precision measurements of the oscillation parameters , including the leptonic @xmath0 phase .
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11,997 |
Suppose that you have an abstract for a scientific paper: we study the free energy and its relevant quantity for the directed polymer in random environment . the polymer is allowed to make unbounded jumps and the environment is given by the bernoulli variables .
we first establish the concentration of the ground state energy of polymer at zero temperature .
secondly , we also prove the same property of the free energy at finite temperature . in the proof ,
we use the fact that the maximum jump of any polymer nearly minimizing energy is not too large with high probability .
this is an interesting property itself from the first passage percolation viewpoint . .
And you have already written the first three sentences of the full article: we discuss models of directed polymer which have unbounded jumps introduced in @xcite .
see @xcite for the background and related works .
the previous paper shows the following three results : ( i ) the continuity of the free energy with respect to inverse temperature and the appearance probability of obstacles ; ( ii ) the asymptotic of the free energy as the appearance probability of obstacles goes to 1 ; ( iii ) the continuity of the time constant of first passage percolation ( fpp ) related to the model . in this paper , we show concentration bounds for the ground state energy , which is nothing but the passage time , and the free energy . as applications ,.
Please generate the next two sentences of the article
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we derive the so - called `` rate of convergence '' results and , based on them , we are able to remove the restriction left in @xcite on a parameter in ( i ) and also give an alternative proof of ( iii ) .
in fact , a concentration bound for the lower tail for fpp is shown in @xcite , proposition 3.1 .
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11,998 |
Suppose that you have an abstract for a scientific paper: tunneling conductance through two quantum dots , which are connected in series to left and right leads , is calculated by using the numerical renormalization group method . as the hopping between the dots increases from very small value , the following states continuously appear ; ( i ) kondo singlet state of each dot with its adjacent - site lead , ( ii ) singlet state between the local spins on the dots , and ( iii ) double occupancy in the bonding orbital of the two dots .
the conductance shows peaks at the transition regions between these states .
especially , the peak at the boundary between ( i ) and ( ii ) has the unitarity limit value of @xmath0 because of coherent connection through the lead - dot - dot - lead . for the strongly correlated cases , the characteristic energy scale of the coherent peak shows anomalous decrease relating to the quantum critical transition known for the two - impurity kondo effect .
the two dots systems give the new realization of the two - impurity kondo problem .
@align#1#2.6ex 2 .
And you have already written the first three sentences of the full article: dilute magnetic impurities in metal bring the single - impurity kondo effect @xcite .
the anti - ferromagnetic coupling between spins on impurities @xmath1 , such as the rkky interaction , would compete with the kondo effect . to study such competition effect ,
the two impurities in metal have been studied extensively @xcite . if the kondo binding energy is much larger than @xmath1 ( @xmath2 ) , each local spin on the magnetic impurity forms the kondo singlet state with the conduction electrons . on the other hand for @xmath3 ,.
Please generate the next two sentences of the article
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the two local spins form the local spin singlet state . from the numerical renormalization group ( nrg )
calculation , jones
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11,999 |
Suppose that you have an abstract for a scientific paper: in this paper , we present an inexact noda iteration with inner - outer iterations for finding the smallest eigenvalue and the associated eigenvector of an irreducible monotone matrix .
the proposed inexact noda iteration contains two main relaxation steps for computing the smallest eigenvalue and the associated eigenvector , respectively .
these relaxation steps depend on the relaxation factors , and we analyze how the relaxation factors in the relaxation steps affect the convergence of the outer iterations . by considering two different relaxation factors for solving the inner linear systems involved , we prove that the convergence is globally linear or superlinear , depending on the relaxation factor , and that the relaxation factor also influences the convergence rate .
the proposed inexact noda iterations are structure preserving and maintain the positivity of approximate eigenvectors .
numerical examples are provided to illustrate that the proposed inexact noda iterations are practical , and they always preserve the positivity of approximate eigenvectors . .
And you have already written the first three sentences of the full article: monotone matrices arise in many areas of mathematics , such as stability analysis @xcite , and bounds for eigenvalues and singular values axels90,axels03 . in many applications ,
one is interested in finding the smallest eigenvalue @xmath0 and the associated eigenvector @xmath1 of an irreducible nonsingular monotone matrix @xmath2 .
the smallest eigenvalue @xmath3 of a monotone matrix @xmath4 is defined as @xmath5 , where @xmath6 denotes the set of eigenvalues of @xmath4 . in @xcite , a real matrix @xmath4.
Please generate the next two sentences of the article
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is called monotone if and only if @xmath7 is a non - negative matrix .
the irreducible nonsingular @xmath8-matrices are one of the most important classes of matrices for applications such as discretized pdes , markov chains @xcite and electric circuits shi96 , and they have been studied extensively in the literature bpl94 .
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