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Suppose that you have an abstract for a scientific paper: we present our study of the hadronization structure of both vector and axial - vector currents leading to decays of the tau into two kaons and a pion .
the cornerstones of our framework are the large-@xmath0 limit of qcd , the chiral structure exhibited at low energies and the proper asymptotic behaviour , ruled by qcd , that is demanded to the associated form factors .
the couplings of the theory are mostly constrained by this procedure and upon the analysis of babar data on @xmath1 we are able to predict the hadronic spectra . .
And you have already written the first three sentences of the full article: we focus on the nonperturbative dynamics of the strong interaction that can be learned thanks to the clean separation of the electroweak and qcd parts in the hadronic decays of the @xmath2 lepton .
advances in the study of the two meson processes have been presented in this workshop @xcite,@xcite .
+ the decay amplitude for the considered decays may be written as : @xmath3 where our lack of knowledge of the precise hadronization mechanism is encoded in the hadronic vector , @xmath4 : @xmath5 symmetries help us to decompose @xmath4 depending on the number of final - state pseudoscalar ( @xmath6 ) mesons , @xmath7 . for three mesons in the final state ,.
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this reads : @xmath8 and @xmath9 @xmath10 , @xmath11 , correspond to the axial - vector current ( @xmath12 ) while @xmath13 drives the vector current ( @xmath14 ) .
the form factors @xmath15 and @xmath16 have a transverse structure in the total hadron momenta , @xmath17 , and drive a @xmath18 transition .
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10,201 |
Suppose that you have an abstract for a scientific paper: we discuss the role of environmental mechanisms in the evolution of dwarf galaxy satellites using high - resolution n - body+sph simulations that include simultaneously tidal forces , ram pressure and heating from ionizing radiation fields .
tidally induced bar - buckling instabilities can transform a rotating disky dwarf into a pressure supported spheroidal .
efficient gas removal requires instead a combination of tidal mass loss and ram pressure stripping in a diffuse gaseous corona around the primary system .
the efficiency of ram pressure depends strongly on how extended the gas remains during the evolution .
bar driven inflows that tend to drive the gas to the bottom of the potential well can be opposed by the heating from external radiation fields .
we show that even fairly massive dwarfs ( @xmath0 30 km / s ) would be stripped of their gas over a few gyr if they enter the milky way halo at @xmath1 thanks to the effect of the cosmic uv background .
gas mass loss can be much faster , occurring in less than 1 gyr , if dwarf satellites have their first close approach with the primary at the epoch of bulge formation .
indeed at that time the primary galaxy should have a fuv luminosity comparable to that of major present - day starbursts , resulting in a local uv field even more intense than the cosmic background . .
And you have already written the first three sentences of the full article: dwarf spheroidals ( dsphs ) are the faintest galaxies known . they are gas poor and have pressure supported stellar components ( mateo 1998 ) . among them some stopped forming stars about 10 gyr ago and other have extended star formation histories ( hernandez et al .
they are typically clustered around the largest galaxy in a group . both mass loss from supernovae winds ( dekel & silk 1986 ) and environmental mechanisms like tidal and ram pressure stipping ( einasto et al . 1974 )
have been invoked to explain their properties ..
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suppression of gas accretion and/or photoevaporation during the reionization epoch likely played a role as well ( bullock et al . 2000 ) . in this paper
we describe the results of n - body / sph simulations of disky dwarf galaxies subject to the combined action of the main environmental mechanisms , tides , ram pressure , and both a cosmic and local ultraviolet radiation field .
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10,202 |
Suppose that you have an abstract for a scientific paper: a remarkable formal similarity between koide s lepton mass formula and a generalized descartes circle formula is reported . +
* keywords : * lepton mass , koide formula , descartes circle theorem , geometry . .
And you have already written the first three sentences of the full article: quarks and leptons are believed to be the fundamental particles of matter yet their nature is still far from being understood .
one of the exciting puzzles is a formula involving the masses of the three leptons , discovered by yoshio koide @xcite : @xmath0 see table 1 for the corresponding numerical values ( from @xcite ) .
[ tbl:1 ] .lepton masses ..
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[ cols= " < , < , < , < , < " , ] * 4 . coda . * whether this intriguing connection with geometry will contribute to an understanding of the masses of leptons remains an interesting question and requires further investigation .
the analogy described above may turn out to be merely superficial , but given the current state of understanding about the matter , any interesting structural parallels are worthy of our consideration in the effort of reconstructing deeper patterns .
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10,203 |
Suppose that you have an abstract for a scientific paper: the collision consistency between the bgk collision model equation and lattice - bgk ( lbgk ) model is proposed by researching the physical significance of the relaxation factor @xmath0 in lbgk model . for microscalar flow
in which the continuum hypothesis is not still satisfied , the collision consistency @xmath1 should be ensured when using the lbgk model for simulating microflows .
the results of simulating microchannel poiseuille flow with constant pressure gradient under collision consistency by using lbgk model are well consistent with the analytical solutions , and the accuracy of these results is three or four orders of magnitude higher than those that do nt satisfy the collision consistency . .
And you have already written the first three sentences of the full article: micro - electro - mechanical systems ( mems ) technology has been developed rapidly in recent years.@xcite~@xcite the characteristic length scale of mems is typically the order of microns , and the ratio of the mean free path to the characteristic dimension ( i.e. knudsen number @xmath2 ) can not be negligible .
the dynamics associated with microchannels can thereby exhibit rarefied phenomena and compressibility effects .
the former is the emergence of a slip velocity at the wall boundary in microchannel flows ..
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the latter is the significant nonlinear pressure drop of gas flowing in a long microchannel . because conducting experiments in micrometer - size is a big challenge , numerical simulations of mems become very important tools of investigation .
but the methods commonly used in simulation of mems , such as molecular dynamics ( md ) , direct simulation monte
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10,204 |
Suppose that you have an abstract for a scientific paper: we show that , if the long grbs are produced by the collapse of massive stars , grbs and their afterglows may provide a powerful probe of cosmology and the early universe . .
And you have already written the first three sentences of the full article: there is increasingly strong evidence that gamma - ray bursts ( grbs ) are associated with star - forming galaxies [ 1,2,3,4 ] and occur near or in the star - forming regions of these galaxies [ 2,3,4,5,6 ] .
these associations provide indirect evidence that at least the long grbs detected by bepposax are a result of the collapse of massive stars .
the discovery of what appear to be supernova components in the afterglows of grbs 970228 [ 7,8 ] and 980326 [ 9 ] provides tantalizing direct evidence that at least some grbs are related to the deaths of massive stars , as predicted by the widely - discussed collapsar model of grbs [ 10,11,12,13,14 ] . if grbs are indeed related to the collapse of massive stars , one expects the grb rate to be approximately proportional to the star - formation rate ( sfr ) ..
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+ + we have calculated the limiting redshifts detectable by batse and hete-2 , and by _ swift _ , for the sixteen grbs with well - established redshifts and published peak photon number fluxes . in doing so
, we have used the peak photon number fluxes given in table 1 of [ 15 ] , taken a detection threshold of 0.2 ph s@xmath0 for batse and hete-2 and 0.04 ph s@xmath0 for _ swift _ , and set @xmath1 km s@xmath0 mpc@xmath0 , @xmath2 , and @xmath3 ( other cosmologies give similar results ) .
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10,205 |
Suppose that you have an abstract for a scientific paper: an effective quantum parameter is obtained for the band ferromagnet in terms of orbital degeneracy and hund s coupling .
this quantum parameter determines , in analogy with @xmath0 for the generalized hubbard model and @xmath1 for quantum spin systems , the strength of quantum corrections to spin stiffness and spin - wave energies .
quantum corrections are obtained by incorporating correlation effects in the form of self - energy and vertex corrections within a spin - rotationally - symmetric approach in which the goldstone mode is explicitly preserved order by order .
it is shown that even a relatively small hund s coupling is rather efficient in strongly suppressing quantum corrections , especially for large @xmath2 , resulting in strongly enhanced stability of the ferromagnetic state .
this mechanism for the enhancement of ferromagnetism by hund s coupling implicitly involves a subtle interplay of lattice , dimensionality , band dispersion , spectral distribution , and band filling effects . .
And you have already written the first three sentences of the full article: experimental studies of magnetic and electronic excitations in various band ferromagnetic systems continue to be of strong current interest , as evidenced by intensive neutron scattering studies of spin - wave excitations throughout the brillouin zone in ferromagnetic manganites highlighting magnon damping and anomalous zone - boundary softening,@xcite angle resolved photoemission spectroscopy ( arpes ) studies of iron to investigate many - body interaction between quasiparticles at the fermi level,@xcite and spin polarized electron energy loss spectroscopy ( speels ) studies of surface spin waves in ultrathin fe films showing strong spin - wave softening due to reduction of exchange interaction.@xcite driven by recent advances in the resolution of experimental probes , these studies provide valuable insight into details of the microscopic mechanism and characteristics of band ferromagnetism .
realistic multi - band calculations of spin - wave dispersion using an itinerant - electron model , in bulk bcc fe e.g. , have so far been carried out only in the random phase approximation ( rpa ) owing to the complexity of the band structure.@xcite recently , a tight - binding model involving 9 orbitals ( 4s , 4p , and 3d ) per fe atom has been used to calculate spin - wave dispersion in the rpa,@xcite and electron self - energy corrections in the ferromagnetic phase of iron were studied in light of recent arpes experiments on fe .
on the other hand , band ferromagnetism being an intrinsically strong - coupling phenomenon , spin - wave excitations in a single - band ferromagnet are strongly renormalized by correlation effects , as studied recently by incorporating self - energy and vertex corrections within a systematic inverse - degeneracy @xmath3 expansion scheme in which the spin - rotation symmetry of the hamiltonian and hence the goldstone mode@xcite are explicitly preserved order by order beyond the rpa.@xcite for the single - band hubbard model , the correlation - induced minority - spin spectral - weight....
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this question is of fundamental importance in view of the multi - band nature of transition - metal ferromagnets , but has not been addressed so far in the literature . in the special case
when the hund s coupling ( inter - orbital interaction ) is identical to the intra - orbital interaction , as obtained in the generalized @xmath2-orbital hubbard model,@xcite the quantum corrections are simply suppressed by the inverse - degeneracy factor @xmath0 . however , for arbitrary hund s coupling , the role of orbital degeneracy on quantum corrections to spin - wave excitations has not been investigated so far . in this paper
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10,206 |
Suppose that you have an abstract for a scientific paper: we apply pauli villars regularization and discretized light - cone quantization to the nonperturbative solution of ( 3 + 1)-dimensional yukawa theory in a single - fermion truncation .
three heavy scalars , including two with negative norm , are used to regulate the theory .
the matrix eigenvalue problem is solved for the lowest - mass state with use of a new , indefinite - metric lanczos algorithm .
various observables are extracted from the wave functions , including average multiplicities and average momenta of constituents , structure functions , and a form factor slope .
# 1 _ # 1 .
And you have already written the first three sentences of the full article: light - cone hamiltonian diagonalization methods offer a number of attractive advantages for solving nonperturbative problems in quantum field theory , such as a physical minkowski space description , boost invariance of the bound - state wave functions , no requirement for fermion doubling , and a consistent fock - state expansion well matched to physical problems . in the discretized light - cone quantization ( dlcq )
method , the light - cone hamiltonian @xmath0 of a quantum field theory is diagonalized on a discrete fock basis defined by assuming periodic boundary conditions in the light - cone coordinates @xcite .
the eigenvalues of @xmath0 give the mass spectrum of the theory , and the respective eigenfunctions projected on the free fock basis provide the frame - independent light - cone wave functions needed for phenomenology @xcite including the amplitudes needed to compute exclusive @xmath1 decays @xcite , deeply virtual compton scattering @xcite , and other hard exclusive processes @xcite ..
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the dlcq method has been successfully used to solve a large number of one - space and one - time theories @xcite , including supersymmetric gauge theories @xcite .
it also has found application in analyzing confinement mechanisms @xcite , string theory @xcite , and @xmath2-theory @xcite . the application of dlcq to physical , ( 3 + 1)-dimensional space - time quantum field theories is computationally challenging because of the rapid growth of the number of degrees of freedom as the size of the fock representation grows .
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10,207 |
Suppose that you have an abstract for a scientific paper: spectroscopic properties of nuclei are accessible with projectile fragmentation reactions , but approximations made in the reaction theory can limit the accuracy of the determinations .
we examine here two models that have rather different approximations for the nucleon wave function , the target interaction , and the treatment of the finite duration of the reaction .
the nucleon - target interaction is treated differently in the eikonal and the transfer - to - continuum model , but the differences are more significant for light targets .
we propose a new parameterization with that in mind .
we also propose a new formula to calculate the amplitude that combines the better treatment of the wave function in the eikonal model with the better treatment of the target interaction in the transfer - to - continuum model . *
pacs * number(s):25.70.hi , 21.10gv,25.60ge,25.70mn,27.20+n * key - words * breakup , absolute cross sections , eikonal approximation , optical potential , s - matrix , t - matrix . .
And you have already written the first three sentences of the full article: heavy ion reactions at intermediate energy offer great promise to measure spectroscopic properties of nuclei far from stability , but one needs a tractable reaction theory to interpret the experiments . in this respective the availability of higher energy heavy ion beams is most welcome , because it becomes a reasonable theoretical approximation to neglect exchange of nucleons between the colliding nuclei .
one can therefore consider the interaction in each nucleus as that of an external ( complex ) potential field . within the framework of this basic approximation and with given potentials , we will here address the question of the accuracy of further simplified models of the reaction cross sections .
a number of theoretical models have been proposed and calculated @xcite-@xcite in which different approximations were made . in this work we focus on two of the models , the eikonal model @xcite-@xcite and the transfer - to - the - continuum ( tc ) model @xcite-@xcite ..
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there are several cross sections that are measured and calculated in the models .
the simplest measurement is the single - neutron removal cross section , in which only the projectile residue , namely the core with one less nucleon , is observed in the final state . besides the integrated removal cross section , denoted by @xmath0 ,
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10,208 |
Suppose that you have an abstract for a scientific paper: the recent advances in 3-d imaging technologies give rise to databases of human shapes , from which statistical shape models can be built .
these statistical models represent prior knowledge of the human shape and enable us to solve shape reconstruction problems from partial information .
generating human shape from traditional anthropometric measurements is such a problem , since these 1-d measurements encode 3-d shape information .
combined with a statistical shape model , these easy - to - obtain measurements can be leveraged to create 3d human shapes . however , existing methods limit the creation of the shapes to the space spanned by the database and thus require a large amount of training data . in this paper , we introduce a technique that extrapolates the statistically inferred shape to fit the measurement data using non - linear optimization .
this method ensures that the generated shape is both human - like and satisfies the measurement conditions .
we demonstrate the effectiveness of the method and compare it to existing approaches through extensive experiments , using both synthetic data and real human measurements . .
And you have already written the first three sentences of the full article: many applications require realistic 3d human shapes .
for instance , 3d human models are used to design products that fit a target population .
typically , these shapes need to have certain characteristics or to be samples from a population ..
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although it is possible to digitize humans using 3d imaging technologies , it is impractical to find and scan suitable human subjects for each individual application . on the other hand
, there is a long history of using anthropometric measurements to describe the human shape .
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10,209 |
Suppose that you have an abstract for a scientific paper: we develop a formulation for constructing and examining rapidly rotating newtonian neutron star models that contain two superfluids , taking account of the effect of the rotation velocity difference between two superfluids .
we assume neutron stars to be composed of the superfluid neutrons and the mixture of the superfluid protons and the normal fluid electrons . to describe newtonian dynamics of the two superfluids , the newtonian version of the so - called two - fluid formalism
is employed .
the effect of the rotation velocity difference on the structure of equilibrium state is treated as a small perturbation to rapidly rotating superfluid stars whose angular velocities of two superfluids are assumed to be exactly the same .
we derive basic equations for the perturbed structures of rapidly rotating superfluid stars due to the rotation velocity difference between two superfluids . assuming the superfluids to obey a simple analytical equation of state proposed by prix , comer , and andersson
, we obtain numerical solutions for the perturbations and find that the density distributions of the superfluids are strongly dependent on the parameter @xmath0 which appears in the analytical equation of state and characterizes the so - called symmetry energy .
it is also found that if prix et al.s analytical equation of state is assumed , the perturbations can be represented in terms of the universal functions that are independent of the parameters of the equation of state .
stars : neutron stars : rotation hydrodynamics .
And you have already written the first three sentences of the full article: to investigate properties of equilibrium configurations of rotating neutron stars , so far , most neutron star models have been obtained by assuming neutron star matter to be a one - constituent perfect fluid ( for a review , see , e.g. stergioulas 2003 ) .
this treatment of equilibrium states of neutron stars seems to be quite reasonable as a first approximation for examining global properties of neutron stars such as the gravitational mass , the radius , or the maximum rotation frequency .
however , it has long been suggested that neutrons in the inner crust and neutrons and protons in the core of neutron stars are in superfluid states when the interior temperatures cool down below @xmath1 ( e.g. , shapiro & teukolsky 1983 ) . since the interior temperature of neutron stars.
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is believed to cool down quickly via the neutrino emission ( e.g. , baym & pethick 1979 ) , it is likely that each of many observable neutron stars , except newly born ones , has a core containing superfluids .
although superfluidity in the interior might be one of the important ingredients that affect the structures of neutron stars , the superfluidity has been neglected in most studies on equilibrium configurations of rotating neutron stars .
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10,210 |
Suppose that you have an abstract for a scientific paper: we study the complete merger of two massive stars inside a common envelope and the subsequent evolution of the merger product , a rapidly rotating massive supergiant .
three qualitatively different types of mergers have been identified and investigated in detail , and the post - merger evolution has been followed to the immediate presupernova stage .
the `` quiet merger '' case does not lead to significant changes in composition , and the star remains a red supergiant . in the case of a `` moderate merger '' , the star may become a blue supergiant and end its evolution as a blue supergiant , depending on the core to total mass ratio ( as may be appropriate for the progenitor of sn 1987a ) . in the case of the most effective `` explosive merger '' , the merger product stays a red giant .
in last two cases , the he abundance in the envelope is increased drastically , but significant s - processing is mainly expected in the .
And you have already written the first three sentences of the full article: it is evident that the internal structure of the progenitor of a core - collapse supernova ( sn ) is one of the dominant factors that determines the characteristics of the supernova explosion , such as the light - curve and the abundances produced in the supernova ( see e.g. @xcite ) .
it has also been shown that the distribution of the angular velocity can produce a strong asymmetry in the nucleosynthesis during the sn explosion and in its ejecta @xcite .
this makes it necessary to follow the detailed evolution of the abundances and the rotation profile at all stages of the evolution of a massive star before it explodes as a core - collapse sn ..
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observationally , it is well established that @xmath0% of all massive stars are members of binary systems with orbital periods shorter than 1 year and that at least 25% of these will start to interact by roche - lobe overflow ( rlof ) during the advanced stages of the primary s evolution @xcite .
this implies that a significant fraction of all core - collapse supernova progenitors will have been affected by a previous binary interaction , where one of the most important interactions is the spiral - in of the two binary components inside a common envelope ( ce ) @xcite .
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10,211 |
Suppose that you have an abstract for a scientific paper: the pompeiu problem is considered as shape optimization problem . we show stability of the ball which is the minimum point of related domain functional . the proof is based on shape derivative method .
stability of the ball for general domain functionals invariant under the rigid motions is discussed . .
And you have already written the first three sentences of the full article: energy type functionals @xmath0 = \iint f\left ( \left| x - y\right| \right ) \xdif { \omega ( x)}\xdif { \omega ( y)}$ ] , where @xmath1 is a measure of compact support , appears in statistical mechanics of systems , topological classification problems of knots , isoperimetric problems , harmonic analysis , discrete energy problems and other areas of pure and applied mathematics ( see , for example , @xcite ) . motivated by problems of shape optimal design @xcite we consider the model domain functional @xmath2 = \int\limits_\omega \int\limits_\omega f\left ( \left| x - y\right| \right )
\xdif x\xdif y,\ ] ] defined on the set of bounded domains @xmath3 with smooth boundaries . here
@xmath4 is known function ..
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let @xmath5 equation @xmath6 will produce a flow @xmath7 which moves a bounded smooth domain @xmath8 to its new position @xmath9 ( see fig .
[ fig1 ] on p. ) . for all @xmath10 close enough to zero the domain
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10,212 |
Suppose that you have an abstract for a scientific paper: we report monte carlo wave function simulation results on cold collisions between magnesium atoms in a strong red - detuned laser field .
this is the normal situation e.g. in magneto - optical traps ( mot ) .
the doppler limit heating rate due to radiative collisions is calculated for @xmath0 mg atoms in a mot based on the @xmath1s@xmath2-@xmath1p@xmath3 atomic laser cooling transition .
we find that radiative heating does not seem to affect the doppler limit in this case .
we also describe a channelling mechanism due to the missing @xmath4 branch in the excitation scheme , which could lead to a suppression of inelastic collisions , and find that this mechanism is not present in our simulation results due to the multistate character of the excitation process . .
And you have already written the first three sentences of the full article: laser cooling and trapping methods are an important ingredient in the recent achievements in the low - temperature physics of gaseous atoms and molecules @xcite . in alkali atoms
one can reach very low temperatures with sisyphus and polarization gradient techniques , which surpass the doppler cooling method in efficiency , and appear in magneto - optical traps without additional efforts @xcite .
the drawback is that it becomes impossible to test the basic two - state doppler cooling theory with these systems ..
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the appearance of sub - doppler cooling is based on the hyperfine structure of the alkali atoms .
the same hyperfine structure is reflected in the complicated molecular state structure of the quasimolecule formed by two colliding atoms . in dilute atomic gases binary collisions
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10,213 |
Suppose that you have an abstract for a scientific paper: we provide a novel insight in the quantum correlations structure present in strongly correlated systems beyond the standard framework of bipartite entanglement . to this aim
we first exploit rotationally invariant states as a test bed to detect genuine tripartite entanglement beyond the nearest - neighbor in spin-1/2 models .
then we construct in a closed analytical form a family of entanglement witnesses which provides a sufficient condition to determine if a state of a many - body system formed by an arbitrary number of spin-1/2 particles possesses genuine tripartite entanglement , independently of the details of the model .
we illustrate our method by analyzing in detail the anisotropic xxz spin chain close to its phase transitions , where we demonstrate the presence of long range multipartite entanglement near the crtical point and the breaking of the symmetries associated to the quantum phase transition . .
And you have already written the first three sentences of the full article: the characterization of entanglement in many - body strongly correlated systems has been a very active research area in the last decade ( see e.g. ref .
@xcite for a review ) .
entanglement is expected to be particularly relevant in quantum phase transitions ( qpt ) and , in order to gather valuable insight , ground states of paradigmatic spin chain models have been exhaustively analyzed ..
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first , it was shown in refs .
@xcite that for the ising chain in a transverse field , pairwise entanglement measured by the concurrence between nearest ( and next - to nearest ) neighbors signals the position of the critical point ( but does not display critical behavior ) while is strictly zero otherwise .
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10,214 |
Suppose that you have an abstract for a scientific paper: the possible solitary wave solutions for a general boussinesq ( gbq ) type fluid model are studied analytically . after proving the non - painlev integrability of the model , the first type of exact explicit travelling solitary wave with a special velocity selection is found by the truncated painlev expansion .
the general solitary waves with different travelling velocities can be studied by casting the problems to the newtonian quasi - particles moving in some proper one dimensional potential fields . for some special velocity selections ,
the solitary waves possess different shapes , say , the left moving solitary waves may possess different shapes and/or amplitudes with those of the right moving solitons .
for some other velocities , the solitary waves are completely prohibited .
there are three types of gbq systems ( gbqss ) according to the different selections of the model parameters .
for the first type of gbqs , both the faster moving and lower moving solitary waves allowed but the solitary waves withmiddle " velocities are prohibit . for the second type of gbqs
all the slower moving solitary waves are completely prohibit while for the third type of gbqs only the slower moving solitary waves are allowed .
.2 in = 0.65 cm [ section ] [ section ] [ section ] [ section ] .
And you have already written the first three sentences of the full article: the study of the korteweg de - vries ( kdv ) equation @xmath0 has been an interesting issue since the discovery of soliton .
its exact solution@xcite can be used to describe the overtaking collision of soliton on a uniform layer of water , but the solution is only physically meaningful for the unidirectional soliton .
all the left moving solitons with zero boundary conditions are prohibited . in ref.@xcite , three sets of model equations are derived for modelling nonlinear and dispersive long gravity waves travelling in two horizontal directions on shallow waters of uniform depth ..
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a good understanding of all solutions of these models are helpful for coastal and civil engineers to apply the nonlinear water wave model in a harbor and coastal design .
therefore , finding more types of solutions of these equations are fundamental interest in fluid dynamics .
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10,215 |
Suppose that you have an abstract for a scientific paper: in this paper we compute certain two - point integrals over a moduli space of stable maps into projective space .
computation of one - point analogues of these integrals constitutes a proof of mirror symmetry for genus - zero one - point gromov - witten invariants of projective hypersurfaces .
the integrals computed in this paper constitute a significant portion in the proof of mirror symmetry for genus-_one _ gw - invariants completed in a separate paper .
these integrals also provide explicit mirror formulas for genus - zero _ two_-point gw - invariants of projective hypersurfaces .
the approach described in this paper leads to a reconstruction algorithm for all genus - zero gw - invariants of projective hypersurfaces . .
And you have already written the first three sentences of the full article: the theory of gromov - witten invariants has been greatly influenced by its interactions with string theory .
in particular , the mirror symmetry principle has led to completely unexpected predictions concerning gw - invariants of calabi - yau manifolds .
the original prediction of @xcite for the genus - zero gw - invariants of a quintic threefold was verified about ten years ago in a variety of ways in @xcite , @xcite , @xcite , @xcite , and @xcite ..
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the 1993 prediction of @xcite for the genus - one gw - invariants of a quintic threefold is verified in @xcite , using the results of this paper . + the proof of the genus - zero mirror symmetry for a projective hypersurface @xmath0 essentially consists of computing certain equivariant integrals on moduli spaces @xmath1 of stable degree-@xmath2 maps from genus - zero curves with @xmath3 marked points into @xmath4 .
while the integrals appearing in chapters 29 and 30 of @xcite are over @xmath5 , the integrands involve only one marked point . for this reason , such integrals can be easily expressed in terms of integrals on @xmath6 and determine genus - zero one - point gw - invariants of @xmath0 ; see _ refz1ptdfn_e1 below . in this paper
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10,216 |
Suppose that you have an abstract for a scientific paper: the atlas and cms experiments have recently claimed discovery of a higgs boson - like particle at @xmath0 confidence and are beginning to test the standard model predictions for its production and decay . in a variety of supersymmetric models ,
a neutralino nlsp can decay dominantly to the higgs and the lsp . in natural susy models ,
a light third generation squark decaying through this chain can lead to large excess higgs production while evading existing bsm searches .
such models can be observed at the 8 tev lhc in channels exploiting the rare diphoton decays of the higgs produced in the cascade decay .
identifying a diphoton resonance in association with missing energy , a lepton , or @xmath1-tagged jets is a promising search strategy for discovery of these models , and would immediately signal new physics involving production of a higgs boson .
we also discuss the possibility that excess higgs production in these susy decays can be responsible for enhancements of up to 50% over the sm prediction for the observed rate in the existing inclusive diphoton searches , a scenario which would likely by the end of the 8 tev run be accompanied by excesses in the @xmath2 and susy multi - lepton/@xmath1 searches and a potential discovery in a @xmath3 search . .
And you have already written the first three sentences of the full article: the atlas and cms experiments at the large hadron collider ( lhc ) have recently reported discovery of a new particle consistent with the higgs boson of the standard model @xcite .
each experiment independently reports nearly @xmath4 combined local significance for a mass of @xmath5 , largely fueled by the searches for resonances in diphoton and @xmath6 final states . the discovery of the higgs marks the final chapter in the quest to discover the particle content of the standard model .
it also represents the start of a new era of higgs physics at the lhc . with additional data and further analyses.
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the experiments will be able to study the properties of this new particle , in particular its production modes and decay branching ratios .
the standard model makes very definite predictions for these properties ( up to calculational uncertainties ) given the mass of the higgs , so any significant deviation from the expected values would be an immediate sign of new physics .
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10,217 |
Suppose that you have an abstract for a scientific paper: aiming for simplicity of explicit equations and at the same time controllable accuracy of the theory we present results for all thermodynamic quantities and correlation functions for the weakly interacting bose gas at short - to - intermediate distances obtained within an improved version of beliaev s diagrammatic technique . with a small symmetry breaking term beliaev s diagrammatic technique becomes regular in the infrared limit .
up to higher - order terms ( for which we present order - of - magnitude estimates ) , the partition function and entropy of the system formally correspond to those of a non - interacting bosonic ( pseudo-)hamiltonian with a temperature dependent bogoliubov - type dispersion relation . away from the fluctuation region , this approach provides the most accurate in fact , the best possible within the bogoliubov - type pseudo - hamiltonian framework description of the system with controlled accuracy .
it produces accurate answers for the off - diagonal correlation functions up to distances where the behaviour of correlators is controlled by generic hydrodynamic relations , and thus can be accurately extrapolated to arbitrarily large scales . in the fluctuation region , the non - perturbative contributions are given by universal ( for all weakly interacting u(1 ) systems ) constants and scaling functions , which can be obtained separately by simulating classical u(1 ) models and then used to extend the description of the weakly interacting bose gas to the fluctuation region .
the theory works in all spatial dimensions and we explicitly check its validity against first - principle monte carlo simulations for various thermodynamic properties and the single - particle density matrix . .
And you have already written the first three sentences of the full article: for nearly half a century the theory of the weakly interacting bose gases ( wibg ) remained in the realm of purely theoretical investigations @xcite ( for a recent review , see @xcite ) providing insight into the nature of superfluid states of matter but not directly relating to existing experimental systems .
the situation changed with the realization of bose einstein condensation in cold atomic gases @xcite .
the typical values of the interaction parameter for alkali atoms are very small @xmath0 , where @xmath1 is the number density of the gas and @xmath2 is the @xmath3-wave scattering length ..
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since 1995 both the theory of wibg and experiments have progressed with a close relationship between the two @xcite . until recently , existing mean - field and variational treatments such as the bogoliubov zero - temperature approximation and the finite - temperature quasi - condensate theory @xcite were capable of describing the data within the relatively large experimental uncertainties .
however , the improvements in detection techniques , the studies of optical lattice systems in which the effective gas parameter can be made arbitrarily large , and the need for reliable thermometry , e.g. , through precise entropy matching , all indicate the need for a more accurate and controllable theory .
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Suppose that you have an abstract for a scientific paper: high resolution low - temperature absorption spectra of 0.2@xmath0 pr@xmath1 doped cscdbr@xmath2 were measured in the spectral region 20007000 @xmath3 .
positions and widths of the crystal field levels within the @xmath4 , @xmath5 , @xmath6 , and @xmath7 multiplets of the pr@xmath8 main center have been determined .
hyperfine structure of several spectral lines has been found .
crystal field calculations were carried out in the framework of the semiphenomenological exchange charge model ( ecm ) .
parameters of the ecm were determined by fitting to the measured total splittings of the @xmath5 and @xmath9 multiplets and to the observed in this work hyperfine splittings of the crystal field levels . one- and two - phonon relaxation rates
were calculated using the phonon green s functions of the perfect ( cscdbr@xmath2 ) and locally perturbed ( impurity dimer centers in cscdbr@xmath2:pr@xmath8 ) crystal lattice .
comparison with the measured linewidths confirmed an essential redistribution of the phonon density of states in cscdbr@xmath2 crystals doped with rare - earth ions . .
And you have already written the first three sentences of the full article: crystals of rare - earth ( re ) doped quasi - one - dimensional double bromides cscdbr@xmath2 are widely studied , mainly , because of their property to incorporate re@xmath8 ions in pairs , even at low re concentrations .
this makes them a promising material for up - conversion lasers .
the structure of cscdbr@xmath2 belongs to the @xmath10 space group and consists of linear chains of face - sharing [ cdbr@xmath11@xmath12 octahedra along the @xmath13-axis ..
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positional symmetry for cd@xmath14 is @xmath15 .
re@xmath8 ions substitute for cd@xmath14 forming centers with different mechanisms of charge compensation .
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Suppose that you have an abstract for a scientific paper: the @xmath0-cell embeddings of graphs on closed surfaces have been widely studied .
it is well known that ( @xmath0-cell ) embedding a given graph @xmath1 on a closed orientable surface is equivalent to cyclically ordering the edges incident to each vertex of @xmath1 . in this paper , we study the following problem : given a genus @xmath2 embedding @xmath3 of the graph @xmath1 and a vertex of @xmath1 , how many different ways of reembedding the vertex such that the resulting embedding @xmath4 is of genus @xmath5 ? we give formulas to compute this quantity and the local minimal genus achieved by reembedding . in the process
we obtain miscellaneous results .
in particular , if there exists a one - face embedding of @xmath1 , then the probability of a random embedding of @xmath1 to be one - face is at least @xmath6 , where @xmath7 denotes the vertex degree of @xmath8 .
furthermore we obtain an easy - to - check necessary condition for a given embedding of @xmath1 to be an embedding of minimum genus .
* keywords : * graph embedding ; genus ; plane permutation ; hypermap mathematics subject classifications 2010 : 05c30 ; 05c10 ; 97k30 .
And you have already written the first three sentences of the full article: graph embedding is one of the most important topics in topological graph theory . in particular ,
@xmath0-cell embeddings of graphs ( loops and multiple edges allowed ) have been widely studied . a @xmath0-cell embedding or map of a given graph @xmath1 on a closed surface of genus @xmath2 , @xmath9 , is an embedding on @xmath9 such that the complement of any face is homeomorphic to an open disk .
the closed surfaces could be either orientable or unorientable . in this paper.
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, we restrict ourselves to the orientable case .
let @xmath10 and @xmath11 denote the minimum and the maximum genus @xmath2 of the embeddings of @xmath1 , respectively .
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Suppose that you have an abstract for a scientific paper: rich clusters of galaxies are the most massive virialized systems known .
even though they contain only a small fraction of all galaxies , rich clusters provide a powerful tool for the study of galaxy formation , dark matter , large - scale structure , and cosmology .
superclusters , the largest known systems of galaxies , extend to @xmath0 mpc in size and highlight the large - scale structure of the universe .
this large - scale structure reflects initial conditions in the early universe and places strong contraints on models of galaxy formation and on cosmology .
some of the questions that can be addressed with clusters and superclusters of galaxies include : how did galaxies and larger structures form and evolve ? what is the amount , composition , and distribution of matter in clusters and larger structures ? how does the cluster mass density relate to the matter density in the universe ?
what constraints can the cluster and supercluster data place on cosmology ?
i will discuss in these lectures some of the properties of clusters and superclusters of galaxies that can be used to investigate these topics . .
And you have already written the first three sentences of the full article: clusters and superclusters of galaxies have been studied extensively both for their intrinsic properties and to investigate the dark matter in the universe , the baryon content of the universe , large - scale structure , evolution , and cosmology . for previous reviews
see zwicky ( 1958 ) , bahcall ( 1977 , 1988 , 1996 ) , oort ( 1983 ) , dressler ( 1984 ) , rood ( 1988 ) , and peebles ( 1993 ) . in these lectures
i discuss the following topics and their implications for structure formation and cosmology ..
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section 2 : : : optical properties of galaxy clusters section 3 : : : x - ray properties of galaxy clusters section 4 : : : the baryon fraction in clusters section 5 : : : cluster masses section 6 : : : where is the dark matter ?
section 7 : : : the mass function of clusters section 8 : : : quasar - cluster association section 9 : : : superclusters section 10 : : : the cluster correlation function section 11 : : : peculiar motions of clusters section 12 : : : some unsolved problems a hubble constant of @xmath1 is used throughout .
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Suppose that you have an abstract for a scientific paper: we report the results of the _ xmm - newton _ observation of the pulsar wind nebula ( pwn ) in the composite supernova remnant g0.9 + 0.1 located in the galactic center region .
thanks to the sensitivity of the epic cameras , we focus on the first spectral analysis of large and small - scale structures of this pwn using mos and pn data in combination .
our spatially resolved spectral analysis at large - scale offers a clear indication of a softening of the photon index with distance from the centroid of the nebula ( from @xmath0=1.12@xmath1 to @xmath2=2.42@xmath3 ) , as observed in other known x - ray plerions .
a spectral analysis of the small - scale structures in the central region of this pwn , delineates variations of the spectral index within the arc - like feature observed with _
chandra _ : the eastern part has a hard photon index ( @[email protected] ) , while the south - west part has a softer photon index ( @[email protected] ) . .
And you have already written the first three sentences of the full article: g0.9 + 0.1 is the only composite snr known in the direction of the gc ( d@xmath6 10kpc , @xmath7@xmath8 ) : a bright centrally condensed synchrotron nebula ( with relatively flat spectral index ) , powered by the loss of rotational energy from the neutron star , and a radio shell with a steeper radio spectrum ( @xcite ) .
@xcite were able to fit the _ bepposax _ x - ray spectrum of the pwn with a power - law and interpret the x - ray emission as non - thermal in origin .
the small angular extent of the x - ray emission ( radius @xmath6 1 ) , combined with an estimated age of the remnant of a few thousand years , is further evidence that the central radio core is powered by a young pulsar ( @xmath6 2,700yr ; @xcite ) ..
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recently , g0.9 + 0.1 was observed with _
chandra _ by @xcite .
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Suppose that you have an abstract for a scientific paper: we detail the enumeration of all two - intersection sets of the five - dimensional projective space over the field of order @xmath0 that are invariant under an element of order @xmath1 , which include the examples of hill ( 1973 ) and gulliver ( 1996 ) . up to projective equivalence
, there are 6635 such two - intersection sets . .
And you have already written the first three sentences of the full article: in the early 1970 s , philippe delsarte showed that there is a remarkable connection between three objects in mathematics : 1 .
strongly regular graphs ; 2 .
linear codes with two weights ; 3 ..
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sets of points in a projective space with two intersection sizes with respect to hyperplanes . to illustrate these connections ,
consider the five - dimensional projective space over the field of order @xmath0 .
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Suppose that you have an abstract for a scientific paper: we present two maximally superintegrable hamiltonian systems @xmath0 and @xmath1 that are defined , respectively , on an @xmath2-dimensional spherically symmetric generalization of the darboux surface of type iii and on an @xmath2-dimensional taub nut space .
afterwards , we show that the quantization of @xmath0 and @xmath1 leads , respectively , to exactly solvable deformations ( with parameters @xmath3 and @xmath4 ) of the two basic quantum mechanical systems : the harmonic oscillator and the coulomb problem . in both cases
the quantization is performed in such a way that the maximal superintegrability of the classical hamiltonian is fully preserved . in particular , we prove that this strong condition is fulfilled by applying the so - called conformal laplace
beltrami quantization prescription , where the conformal laplacian operator contains the usual laplace
beltrami operator on the underlying manifold plus a term proportional to its scalar curvature ( which in both cases has non - constant value ) . in this way
, the eigenvalue problems for the quantum counterparts of @xmath0 and @xmath1 can be rigorously solved , and it is found that their discrete spectrum is just a smooth deformation ( in terms of the parameters @xmath3 and @xmath4 ) of the oscillator and coulomb spectrum , respectively
. moreover , it turns out that the maximal degeneracy of both systems is preserved under deformation .
finally , new further multiparametric generalizations of both systems that preserve their superintegrability are envisaged .
ngel ballesteros@xmath5 , alberto enciso@xmath6 , francisco j. herranz@xmath7 + orlando ragnisco@xmath8 and danilo riglioni@xmath9 @xmath5 departamento de fsica , universidad de burgos , e-09001 burgos , spain @xmath6 instituto de ciencias matemticas , csic , nicols cabrera 13 - 15 , e-28049 madrid , spain @xmath10 dipartimento di matematica e fisica , universit di roma tre and istituto nazionale di fisica nucleare sezione di roma tre , via vasca navale 84 ,....
And you have already written the first three sentences of the full article: it is well known that if we consider a natural classical hamiltonian system on the @xmath2-dimensional ( @xmath2d ) euclidean space = t()+u ( ) , [ uno ] the harmonic oscillator potential @xmath12 and the coulomb potential @xmath13 define two _ maximally superintegrable _ ( ms ) systems ( in the liouville sense ) , since both systems are endowed with @xmath14 functionally independent and globally defined integrals of the motion . in the first case
such integrals are provided by the components of the demkov
fradkin tensor @xcite , and in the second one by the angular momenta together with the @xmath2 components of the runge .
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lenz vector ( see e.g. @xcite and references therein ) . at the classical dynamical level , the footprint of superintegrability consists in the fact that all bounded trajectories of these two systems are closed ones , a fact which is diretly related with bertrand s theorem @xcite .
moreover , when the quantization of these systems is performed it is found that such superintegrability implies that their spectrum exhibits maximal degeneracy due to a superabundance of quantum integrals of the motion . in this paper
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Suppose that you have an abstract for a scientific paper: the stability of a nambu - goto membrane at the equatorial plane of the reissner - nordstrm - de sitter spacetime is studied .
the covariant perturbation formalism is applied to study the behavior of the perturbation of the membrane .
the perturbation equation is solved numerically .
it is shown that a membrane intersecting a charged black hole , including extremely charged one , is unstable and that the positive cosmological constant strengthens the instability .
* instability of a membrane intersecting a black hole * susumu higaki@xmath0 , akihiro ishibashi@xmath1 and daisuke ida@xmath0 + @xmath0_department of physics , kyoto university , kyoto 606 - 8502 , japan _
+ @xmath1_yukawa institute for theoretical physics , kyoto university , kyoto 606 - 8502 , japan _ .
And you have already written the first three sentences of the full article: it is believed that in the early universe a series of vacuum phase transitions led to several types of topological defects @xcite .
topological defects are relics of the early universe and are expected to convey some information on physics of very high energy scales beyond our reach with ground - based accelerators . on the other hand , topological defects are candidates for the seed of the observed large scale structure of the universe such as sheet - like or filamentary structures or voids .
thus topological defects are attractive examples which connect the high energy physics and cosmology and we might be able to have some information on high energy physics through cosmological observations such as gravitational wave detection in future ..
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topological defects , if they existed , would interact with other strong gravitational sources such as black holes , and then they might have experienced large deformation and emitted some information on themselves as gravitational waves . if we succeed in detecting such gravitational waves and identifying them , we will be able to confirm the existence of topological defects and hence the occurrence of a vacuum phase transition .
the topological defects with finite extent such as the cosmic string or the domain wall are known to produce an unusual gravitational field @xcite and their dynamics are slightly complicated .
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Suppose that you have an abstract for a scientific paper: we have identified a large - scale structure at @xmath0 in the cosmos field , coherently described by the distribution of galaxy photometric redshifts , an acs weak - lensing convergence map and the distribution of extended x - ray sources in a mosaic of xmm observations .
the main peak seen in these maps corresponds to a rich cluster with @xmath1 kev and @xmath2 erg s@xmath3 ( @xmath4 $ ] kev band ) .
we estimate an x - ray mass within @xmath5 corresponding to @xmath6 m@xmath7 and a total lensing mass ( extrapolated by fitting a nfw profile ) @xmath8 .
we use an automated morphological classification of all galaxies brighter than @xmath9 over the structure area to measure the fraction of early - type objects as a function of local projected density @xmath10 , based on photometric redshifts derived from ground - based deep multi - band photometry .
we recover a robust morphology - density relation at this redshift , indicating , for comparable local densities , a smaller fraction of early - type galaxies than today .
interestingly , this difference is less strong at the highest densities and becomes more severe in intermediate environments .
we also find , however , local `` inversions '' of the observed global relation , possibly driven by the large - scale environment .
in particular , we find direct correspondence of a large concentration of disk galaxies to ( the colder side of ) a possible shock region detected in the x - ray temperature map and surface brightness distribution of the dominant cluster .
we interpret this as potential evidence of shock - induced star formation in existing galaxy disks , during the ongoing merger between two sub - clusters .
our analysis reveals the value of combining various measures of the projected mass density to locate distant structures and their potential for understanding the physical processes at work in the transformation of galaxy morphologies . .
And you have already written the first three sentences of the full article: the gravitational instability paradigm assumes that large - scale structure in the universe evolves in a hierarchical fashion , forming larger and larger systems via the assembly of smaller sub - units .
it is natural to think that the development of this structure should have a significant effect on the properties of galaxies that we observe today and that a strong correlation between these and the surrounding environment should be in general observed .
one of the most evident correlations of galaxy properties with the environment in the present - day universe is the morphology - density ( md ) relation : early - type galaxies , i.e. @xmath11 and @xmath12 ( _ spheroidal _ ) gas - poor objects are preferentially found in dense environments , such as groups and clusters ( oemler 1974 , dressler 1980 , giovanelli , haynes & chincarini 1986 ) ..
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measurements now exist also at redshifts up to unity , that show a similar relationship to be already in place at earlier times ( dressler et al .
1997 , andreon 1998 , smith et al .
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Suppose that you have an abstract for a scientific paper: we examine the hypothesis that some supernova remnants ( snrs ) may be responsible for some unidentified @xmath0-ray sources detected by egret instrument aboard the compton gamma ray observatory .
if this is the case , @xmath0-rays are produced via pion production and decay from direct inelastic collisions of accelerated by snr shock wave ultrarelativistic protons with target protons of the interstellar medium .
we develop a 3-d hydrodynamical model of snr ic 443 as a possible cosmic @xmath0-ray source 2eg j0618 + 2234 .
the derived parameters of ic 443 : the explosion energy @xmath1 erg , the initial hydrogen number density @xmath2 @xmath3 , the mean radius @xmath4 pc and the age @xmath5 yr result in too low @xmath0-ray flux , mainly because of the low explosion energy .
therefore , we investigate in detail the hydrodynamics of ic 443 interaction with a nearby massive molecular cloud and show that the reverse shock wave considerably increases the cosmic ray density in the interaction region .
meantime , the rayleigh - taylor instability of contact discontinuity between the snr and the cloud provides an effective mixing of the containing cosmic ray plasma and the cloud material .
we show that the resulting @xmath0-ray flux is consistent with the observational data .
supernova remnants , individual : ic 443 , x - rays , cosmic rays , @xmath0-rays 98.38.mz , 98.70.qy , 98.70.rz , 98.70.sa .
And you have already written the first three sentences of the full article: supernova remnants ( snrs ) are believed to be the most promising accelerators of ultrarelativistic particles ( electrons , protons and nuclei ) in our galaxy @xcite .
they are responsible for the majority of cosmic rays ( crs ) with energies up to @xmath6 ( lorentz factor of proton @xmath7 ) .
classical observations of synchrotron radiation from snrs , mainly in the radio band , give experimental confirmation of the presence of relativistic electrons in these cosmic objects @xcite ..
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recently , the presence of ultrarelativistic electrons in snrs has been confirmed by optical , x - ray and soft @xmath0-ray observations @xcite .
there are expected two main cr accelerators in snr .
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Suppose that you have an abstract for a scientific paper: the kamioka liquid - scintillator anti - neutrino detector ( kamland ) has detected for the first time the disappearance of electron antineutrinos from a terrestrial source at the 99.95% c.l.@xcite interpreted in terms of neutrino oscillations @xmath0 , the best fit to the kamland data gives a mixing angle @xmath1 and a mass - squared difference @xmath2 ev@xmath3 , in excellent agreement with the large mixing angle ( lma ) solution to the `` solar neutrino problem''.@xcite assuming cpt invariance , this result excludes other solutions to the solar neutrino problem at @xmath4 99.95% c.l . epsf .
And you have already written the first three sentences of the full article: nuclear reactors emit a calculable flux of electron antineutrinos ( @xmath5s ) in all directions . for standard particle propagation ,
one expects a detector located a distance @xmath6 from the reactor to measure a flux that decreases as @xmath7 .
but if @xmath5s are massive , they may `` oscillate '' into undetectable flavors on the way to the detector , leading to an apparent `` disappearance '' of the @xmath5s ..
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neutrinos are produced and detected in weak interactions , which couple to the weak eigenstates @xmath8 , where @xmath9 . for massive neutrinos
, the weak eigenstates may be expressed as a linear combination of three mass eigenstates @xmath10 , @xmath11 , with mass @xmath12 : @xmath13 @xmath14 is a @xmath15 unitary `` mixing '' matrix and is analogous to the ckm matrix in the quark sector . as a neutrino propagates through vacuum with momentum @xmath16 , the phase of each mass eigenstate will change at different rates according to @xmath17 where @xmath18 . at times
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Suppose that you have an abstract for a scientific paper: strong and weak decays of pentaquarks are studied in the framework of the light - front approach . .
And you have already written the first three sentences of the full article: the discovery of an exotic @xmath0 pentaquark by leps at spring-8,@xcite subsequently confirmed by many other groups , marked a new era for testing our understanding of the hadron spectroscopy and promoted a re - examination of the qcd implications for exotic hadrons .
the mass of the @xmath0 is of order 1535 mev and its width is less than 10 mev from direct observations and can be as narrow as 1 mev or even lower.@xcite many null results for the pentaquark search mostly from high energy experiments have also been reported .
therefore , if the @xmath0 pentaquark is real , it must be established beyond any doubt . if the @xmath0 pentaquark exists , its minimum quark content is @xmath1 . to understand those experimental measurements with positive results.
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, we are facing three puzzles : ( i ) the doubly charged partner of @xmath0 , namely , @xmath2 with the quark content @xmath3 , should be easily detected via the decay @xmath4 .
the puzzle is why is it not seen so far while stringent limits have been set ?
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Suppose that you have an abstract for a scientific paper: we use a simple model to study the long time fluctuations induced by random pinning on the motion of driven non interacting vortices . we find that vortex motion seen from the co moving frame is diffusive and anisotropic , with velocity dependent diffusion constants .
longitudinal and transverse diffusion constants cross at a characteristic velocity where diffusion is isotropic .
the diffusion front is elongated in the direction of the drive at low velocities and elongated in the transverse direction at large velocities .
we find that the mobility in the driven direction is always larger than the transverse mobility , and becomes isotropic only in the large velocity limit .
random pinning , diffusion , mobility 74.25.qt .
And you have already written the first three sentences of the full article: understanding the non equilibrium statistical properties of driven particles in disordered media is a challenging question relevant to many experimental situations .
a prominent example are the moving phases of driven vortex lattices in superconductors @xcite .
a key feature of these systems is that the disorder induces anisotropic response and fluctuations which are strongly controlled by the velocity @xcite . in spite of its relevance to understand situations of incoherent or plastic vortex flow.
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the simple case of an isolated vortex driven in a @xmath0-dimensional random potential with @xmath1 has been tackled analitically only by perturbation theory @xcite , valid at high velocities , or by mean field theory @xcite , valid for @xmath2 . in this paper
we propose a simple model whose long time behaviour can be computed analitically at @xmath3 for any finite velocity .
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Suppose that you have an abstract for a scientific paper: the dependence on the single - particle states of the pairing matrix elements of the gogny force and of the bare low - momentum nucleon - nucleon potential @xmath0 - designed so as to reproduce the low - energy observables avoiding the use of a repulsive core - is studied in the semiclassical approximation for the case of a typical finite , superfluid nucleus ( @xmath1sn ) .
it is found that the matrix elements of @xmath0 follow closely those of @xmath2 on a wide range of energy values around the fermi energy @xmath3 , those associated with @xmath0 being less attractive .
this result explains the fact that around @xmath3 the pairing gap @xmath4 associated with the gogny interaction ( and with a density of single - particle levels corresponding to an effective @xmath5-mass @xmath6 ) is a factor of about 2 larger than @xmath7 , being in agreement with @xmath8= 1.4 mev .
the exchange of low - lying collective surface vibrations among pairs of nucleons moving in time - reversal states gives rise to an induced pairing interaction @xmath9 peaked at @xmath3 .
the interaction @xmath10 arising from the renormalization of the bare nucleon - nucleon potential and of the single - particle motion ( @xmath11mass and quasiparticle strength @xmath12 ) due to the particle - vibration coupling leads to a value of the pairing gap at the fermi energy @xmath13 which accounts for the experimental value .
an important question which remains to be studied quantitatively is to which extent @xmath4 , which depends on average parameters , and @xmath13 , which explicitly depends on the parameters describing the ( low - energy ) nuclear structure , display or not a similar isotopic dependence , and whether this dependence is born out by the data . * pairing matrix elements and pairing gaps with bare , effective and induced interactions * f. barranco@xmath14 , p.f .
bortignon@xmath15 , r.a .
broglia@xmath16 , g. col@xmath15 , + p. schuck@xmath17 , e. vigezzi@xmath18 and x. vias@xmath19 + @xmath14 departamento de....
And you have already written the first three sentences of the full article: an economic description of pairing correlations in finite nuclei is provided by hartree - fock - bogoliubov ( hfb ) theory @xcite making use of phenomenological interactions like e.g. the finite range gogny force @xcite or density dependent zero - range forces combined with appropriate energy cut - offs ( cf .
, e.g. , @xcite ) .
such a description leads to values of the pairing gap which are in overall agreement with the experimental findings ..
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note that in these calculations , the density of levels at the fermi energy @xmath22 is controlled by the so called @xmath23mass ( i.e. @xmath24 ) which , as a rule , is smaller than the bare nucleon mass ( e.g. @xmath25 in the case of the gogny force )
. on the other hand , a number of studies have shown that the superfluid properties of nuclear systems , ranging from infinite nuclear and neutron matter to finite atomic nuclei , are strongly influenced by polarization phenomena @xcite . in these calculations
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Suppose that you have an abstract for a scientific paper: we have developed photometric techniques that can be applied to images with highly - variable backgrounds , as well as to slightly - extended objects ( object size comparable to or smaller than psf size ) .
we have shown that ordinary stellar psf - fitting photometry can be applied to slightly - extended objects , provided that one applies a systematic correction to the photometry that is a function primarily of the observed sharpness . applying these techniques to the cepheid target ngc 3627 , we find that we are successfully able to photometer the stars and clusters , as well as discriminating the cluster population with a negligible number of false detections . .
And you have already written the first three sentences of the full article: for decades it has been well established that the population of star clusters in the milky way is strongly bimodal , with a population of old , massive , and compact globular clusters in the galactic spheroid and a physically distinct population of less populous open clusters in the disk .
however a growing body of observations suggests that this distinction is less pronounced in other types of galaxies , and that the nature of the young and intermediate - age cluster populations differs dramatically in different galactic environments .
early studies of the star cluster populations in the magellanic clouds revealed the presence of young and intermediate age `` populous blue clusters '' or `` blue globular clusters '' that are absent in the milky way @xcite , and similar populations have been found in m33 and other nearby late - type galaxies @xcite ..
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populations of very massive `` super star clusters '' have been found in starburst galaxies and strongly interacting galaxies @xcite , leading to the speculation that many of these objects are progenitors of globular clusters @xcite .
other observations obtained over the past 15 years show that the specific frequencies and mass spectra of young stellar associations vary systematically along the hubble sequence .
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Suppose that you have an abstract for a scientific paper: we consider the two flavor version of the linear sigma model as well as of the nambu jona - lasinio model , at finite temperature and quark chemical potential , beyond the mean field approximation .
using parameter values for the pion and quark current masses which weakly break chiral symmetry we show that both models can present more than one critical end point .
in particular , we explicitly show that the appearance of a new critical point associated with a first order line at high temperature and low densities could help to conciliate some lattice results with model predictions . using different techniques , we perform an extensive thermodynamical analysis to understand the physical nature of the different critical points . for both models ,
our results suggest that the new first order line which starts at vanishing chemical potential has a more chiral character than the usual line which displays a character more reminiscent of a liquid - gas phase transition . .
And you have already written the first three sentences of the full article: numerical analyses of quantum chromodynamics ( qcd ) on a discrete space - time lattice ( lattice qcd ) , indicate that the transition from confined to deconfined matter at finite temperature @xmath0 and vanishing quark chemical potential @xmath1 is a crossover @xcite .
on the other hand , model studies @xcite predict a first - order transition to occur for @xmath1 of the order of @xmath2 of the baryon mass and @xmath3 . in between these two regimes , a second - order critical point is expected in the @xmath4 plane at some intermediate values of @xmath0 and @xmath1 .
the existence and the exact location of the critical point is still a matter of dispute @xcite and has been under intense theoretical study using effective field theory models of qcd @xcite ( see also the recent analysis performed in ref ..
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unfortunately , a direct application of lattice qcd at finite @xmath1 is , at present , still quite problematic . only relatively recently , new theoretical developments and technical improvements allowed to circumvent in various ways the fermion determinant problem and start performing monte - carlo calculations ( see ref .
@xcite for a review ) .
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Suppose that you have an abstract for a scientific paper: motivated by leinster - cobbold measures of biodiversity , the notion of the spread of a finite metric space is introduced .
this is related to leinster s magnitude of a metric space .
spread is generalized to infinite metric spaces equipped with a measure and is calculated for spheres and straight lines . for riemannian manifolds the spread
is related to the volume and total scalar curvature . a notion of scale - dependent dimension
is introduced and seen , numerically , to be close to the hausdorff dimension for approximations to certain fractals . .
And you have already written the first three sentences of the full article: given a finite metric space @xmath0 with metric @xmath1 we define the spread @xmath2 by @xmath3 this is one of a family of metric space ` sizes ' as we will see in section [ section : leinstercobbold ] where we will also see the motivation for this definition .
this generalizes easily from finite metric spaces to arbitrary metric spaces with a measure , as will be seen in section [ section : measurespaces ] .
one of the things that we will be interested in is how this measure of size alters as the metric is scaled , so we need to define some notation . for @xmath4.
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let @xmath5 denote the metric space @xmath0 with the metric @xmath1 scaled up by a factor of @xmath6 , so that the distance in @xmath5 between @xmath7 and @xmath8 is @xmath9 .
we can consider the spread profile of the space @xmath0 which is just the graph of @xmath10 for @xmath4 .
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Suppose that you have an abstract for a scientific paper: we observed the _ j _ = @xmath0 and @xmath1 rotational transitions of the normal species and five @xmath2c isotopologues of hc@xmath3n to study its formation mechanisms toward the cyanopolyyne peak in taurus molecular cloud-1 , with the 45-m radio telescope of nobeyama radio observatory .
we detected the five @xmath2c isotopologues with high signal - to - noise ratios between 12 and 20 , as well as the normal species .
the abundance ratios of the five @xmath2c isotopologues of hc@xmath3n are found to be @xmath4 ( @xmath5 ) ( 1@xmath6 ) for @xmath7h@xmath2cccccn@xmath8 : [ $ ] hc@xmath2ccccn@xmath8 : [ $ ] hcc@xmath2cccn@xmath8 : [ $ ] hccc@xmath2ccn@xmath8 : [ $ ] hcccc@xmath2cn@xmath8 $ ] .
we do not find any significant differences among the five @xmath2c isotopologues .
the averaged [ hc@xmath3n]/[@xmath2c isotopologues ] abundance ratio is determined to be @xmath9 ( 1@xmath6 ) , which is slightly higher than the local interstellar elemental @xmath10c/@xmath2c ratio of @xmath11 .
possible formation pathways are discussed on the basis of these results . .
And you have already written the first three sentences of the full article: more than 180 molecules have been detected in the interstellar medium and circumstellar shells of evolved stars , and approximately 40% of them are classified into carbon - chain molecules .
it is therefore of fundamental importance for astrochemistry to study their formation processes .
however , these molecules are so reactive due to unsaturated chemical bonds and/or unpaired electrons that laboratory measurements of their reaction rates are not routine experiments . although formation mechanisms of the carbon - chain molecules have mainly been studied by chemical model calculations ( e.g. * ? ? ?.
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* ; * ? ? ?
* ) , it is still difficult to reproduce molecular abundances derived by observations , and to determine formation mechanisms of carbon - chain molecules , because of uncertain rate coefficients and of poor knowledge of elementary reactions involving carbon - chain molecules .
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Suppose that you have an abstract for a scientific paper: we review the contribution of extra galactic inspiralling double neutron stars , to the lisa astrophysical gravitational wave foreground . using recent fits of the star formation rate ,
we show that sources beyond @xmath0 contribute to a truly continuous background , which may dominate the lisa instrumental noise in the range @xmath1 - @xmath2 hz and overwhelm the galactic wd - wd confusion noise at frequencies larger than @xmath3 . .
And you have already written the first three sentences of the full article: compact neutron star binaries are among the most promising sources of gravitational waves . at low frequencies ,
the continuous inspiral signal may be detectable by the space antenna lisa , while ground based interferometers such as virgo @xcite , ligo @xcite , geo @xcite or tama @xcite , are expected to detect the last few minutes prior coalescence , at frequencies up to 1.4 - 1.6 khz . in a first paper @xcite ( hereafter paper i ) ,
we have investigated the high frequency signal and its detection with the first generations of ground based detectors . using new estimates of the mean merging rate in the local universe , that account for the galactic star formation history derived directly from observations and.
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include the contribution of elliptical galaxies , we predict a detection every 148 and 125 years in the volume probed by initial virgo and ligo , and up to 6 detections per year in their advanced configuration . in a second paper @xcite ( hereafter paper ii ) , we used numerical simulations to estimate the gravitational wave emission produced by the superposition of unresolved extra - galactic sources .
as in paper i , we were interested in the few sixteen minutes before the last stable orbit is reached , when more than 96% of the gravitational wave energy is released and when the frequency evolves in the range 10 - 1500 hz , covered by ground based interferometers .
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Suppose that you have an abstract for a scientific paper: we present six new and two previously published high - resolution spectra of the quasar hs 1603 + 3820 ( @xmath0 ) taken over an interval of 4.2 years ( 1.2 years in the quasar rest frame ) .
the observations were made with the high - dispersion spectrograph on the subaru telescope and medium - resolution spectrograph on the hobby - eberly telescope .
the purpose was to study the narrow absorption lines ( nals ) .
we use time variability as well as coverage fraction analysis to separate intrinsic absorption lines , which are physically related to the quasar , from intervening absorption lines . by fitting models to the line profiles , we derive the parameters of the respective absorbers as a function of time .
only the mini - bal system at @xmath1 ( @xmath2 ) shows both partial coverage and time variability , although two nal systems possibly show evidence of partial coverage .
we find that all the troughs of the mini - bal system vary in concert and its total equivalent width variations resemble those of the coverage fraction .
however , no other correlations are seen between the variations of different model parameters .
thus , the observed variations can not be reproduced by a simple change of ionization state nor by motion of a homogeneous parcel of gas across the cylinder of sight .
we propose that the observed variations are a result of rapid continuum fluctuations , coupled with coverage fraction fluctuations caused by a clumpy screen of variable optical depth located between the continuum source and the mini - bal gas .
an alternative explanation is that the observed partial coverage signature is the result of scattering of continuum photons around the absorber , thus the equivalent width of the mini - bal can vary as the intensity of the scattered continuum changes . .
And you have already written the first three sentences of the full article: quasars have been used as background sources to study the gaseous phases of a variety of objects that are located along our sight - lines to them .
these objects include not only _ intervening _ absorbers such as intervening galaxies , the intergalactic medium ( igm ) , clouds in the halo of the milky way , and the host galaxies of the quasars themselves , but also _ intrinsic _ absorbers that are physically associated with the quasar central engines .
one of the most promising candidates for the intrinsic absorbers are outflowing winds from the quasars that could be accelerated by radiation pressure from the accretion disk ( murray et al ..
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1995 ; arav et al . 1995 ; proga et al .
2000 ) or by magnetocentrifugal forces ( e.g. , everett 2005 ) .
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Suppose that you have an abstract for a scientific paper: x - ray timing observations of neutron stars and black holes are among the few available probes of ultrastrong magnetic fields , strong gravity , high densities , and the propagation of thermonuclear burning . here
we review the evidence for these effects revealed with data from the rossi explorer in the last five years .
we also discuss the exciting prospects for making the first quantitative tests of strong - gravity general relativistic predictions with a large - area x - ray timing mission .
# 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: x - ray timing has historically led to fundamental understanding of many phenomena , such as accretion - powered pulsars , low - mass x - ray binaries , and strongly magnetized neutron stars .
x - ray timing has unique power because timing signals are often clean diagnostics of systems , and hence lead directly to physical understanding . here
we discuss recent results of x - ray timing ..
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in particular , we focus on aspects of fundamental physics that can be addressed with timing observations .
physics in ultrastrong magnetic fields , high densities , and strong gravity can all be tested with such observations , which reveal truly small - scale structure , from the @xmath0 cm sizes of neutron stars and black holes to the @xmath1 cm radii of nucleons . in
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Suppose that you have an abstract for a scientific paper: we propose a new approach to study the relation between the module categories of a tilted algebra @xmath0 and the corresponding cluster - tilted algebra @xmath1 .
this new approach consists of using the induction functor @xmath2 as well as the coinduction functor @xmath3 .
we show that @xmath4 is a partial tilting and a @xmath5-rigid @xmath0-module and that the induced module @xmath6 is a partial tilting and a @xmath5-rigid @xmath7-module . furthermore ,
if @xmath8 for a tilting module @xmath9 over a hereditary algebra @xmath10 , we compare the induction and coinduction functors to the buan - marsh - reiten functor @xmath11 from the cluster - category of @xmath10 to the module category of @xmath7 .
we also study the question which @xmath7-modules are actually induced or coinduced from a module over a tilted algebra . .
And you have already written the first three sentences of the full article: cluster - tilted algebras are finite dimensional associative algebras which were introduced in @xcite and , independently , in @xcite for the type @xmath12 .
one motivation for introducing these algebras came from fomin and zelevinsky s cluster algebras @xcite . to every cluster in an acyclic cluster algebra one can associate a cluster - tilted algebra , and the indecomposable rigid modules over the cluster - tilted algebra correspond bijectively to the cluster variables outside the chosen cluster .
generalizations of cluster - tilted algebras , the jacobian algebras of quivers with potentials , were introduced in @xcite , extending this correspondence to the non - acyclic types ..
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many people have studied cluster - tilted algebras in this context , see for example @xcite .
the second motivation came from classical tilting theory .
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Suppose that you have an abstract for a scientific paper: prospective power supply systems based on renewable energy sources require measures to balance power generation and load at all times .
the utilisation of storage devices and backup power plants is widely suggested for this purpose , whereas the best combination is still to be found . in this work
, we present a modelling approach to systematically study scenarios of future power supply systems with a high share of electricity originating from wind and solar resources . by considering backup as a subordinate source of electricity with energy - only costs ,
the approach is independent of the actual full - load hours of the backup power plants . applying the approach to multi - year meteorological data for germany
, cost - optimised combinations of storage devices and backup power are identified .
we find that even in scenarios with significant excess generation capacities there is a need for storage devices or backup power plants with discharging power on the same order as the average load to balance the system at all times .
furthermore , these capacities seem to be required in some years of the multi - year period only .
our results imply that the societal need of having electricity available at all times can likely be satisfied by installing over - capacities only , whereas a balance has to be found between installing additional backup or storage or generation capacities .
energy storage , power system , optimisation .
And you have already written the first three sentences of the full article: many countries throughout the developed world are currently in the long - term process of changing their electricity supply system from one based on fossil and nuclear fuels to one based on renewable energy sources ( res ) .
multiple studies have shown that an electricity supply system based entirely on res is possible not only in large - interconnected systems like europe ( e.g. @xcite ) and the united states ( e.g. @xcite ) , but also in isolated national systems ( e.g. @xcite ) . in many studies dealing with a prospective european power supply systems based on res , a large share of the electricity
will be provided by variable renewable energy sources ( vres ) , which are in particular solar and wind resources @xcite ..
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a power supply system based mainly on vres requires measures to cope with the natural variability of the power production from these resources in order to ensure our current high security of supply .
an option widely considered is the utilisation of storage devices . here
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Suppose that you have an abstract for a scientific paper: we present epoch 1996 , high - quality radial velocity data for hde 226868 , the optical counterpart of cygnus x-1 . combining our results with all published historical data , we have derived a new ephemeris for the system of hjd2450235.29 @xmath0 , which allows accurate orbital phase calculations to be made for any x - ray observations over the last 30 years .
we find no evidence for any period change as has been suggested by ninkov , walker & yang ( 1987 ) .
we discuss the shortcomings of previous work in establishing the period and orbital elements .
# 1*#1 * x - rays : stars binaries : close stars : individual : cyg x-1 accretion , accretion discs .
And you have already written the first three sentences of the full article: cygnus x-1 , identified with the bright ( v@xmath18 ) star hde226868 ( bolton 1972 ; webster & murdin 1972 ) , has long been regarded as the best black hole candidate among the high - mass x - ray binaries . as such , it has been an object of extensive observation over the past two and a half decades . perhaps surprisingly , there remain some important uncertainties and discrepancies in the derived properties of the system . in particular , ninkov , walker , & yang ( 1987 , hereafter nwy ) report evidence of possible period variation , discussed below , and additional periodicities on timescales ranging from 39 days to 4.5 years have been suggested by kemp , herman , & barbour ( 1978 ) , wilson and fox ( 1981 ) , priedhorsky , terrell , & holt ( 1983 ) , and walker and quintanilla ( 1978 ) .
+ hde226868 is a single - lined spectroscopic binary .
the optical spectrum has been classified o9.7iab by walborn ( 1973 ) , with variable emission at heii @xmath24686 and , less prominently , at the balmer lines ..
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the radial velocity period of 5.6 days has been established for over two decades , and the definitive orbital elements and ephemeris were published by gies and bolton ( 1982 , hereafter gb ) .
they give a period of 5.59974 @xmath3 0.00008 days , a precision which translates to an uncertainty of only @xmath30.02 cycle in phase at the present time .
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Suppose that you have an abstract for a scientific paper: this paper studies the non - spherical perturbations of the continuously self - similar critical solution of the gravitational collapse of a massless scalar field ( the roberts solution ) .
the exact analysis of the perturbation equations reveals that there are no growing non - spherical perturbation modes . .
And you have already written the first three sentences of the full article: choptuik s discovery of critical phenomena in the gravitational collapse of a scalar field @xcite sparked a surge of interest in gravitational collapse just at the threshold of black hole formation .
the discovery of critical behavior in several other matter models quickly followed .
despite the fact that the evolution equations are very complex and highly non - linear , the dynamics of the near - critical field evolution is relatively simple and , in some important aspects , universal ..
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the critical solution , which depends on the matter model only , serves as an intermediate attractor in the phase space of solutions , and often has an additional peculiar symmetry called self - similarity .
the mass of the black hole produced in supercritical evolution scales as a power law @xmath0 with parameter @xmath1 describing initial data , and mass - scaling exponent @xmath2 is dependent only on the matter model , but not on the initial data family . an interesting consequence of mass scaling which has direct bearing on the cosmic censorship conjecture is the fact that arbitrarily small black holes can be produced in near - critical collapse , with the critical solution exhibiting a curvature singularity and no event horizon .
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Suppose that you have an abstract for a scientific paper: properties of the @xmath0 superfluid phase are studied for symmetric nuclear matter at finite temperature .
it is described within a covariant hadronic field model , of the @xmath1 type , with addition of density dependent correlations simulating effects due to finite extension of nucleons .
the model is solved in a selfconsistent hartree - bogoliubov approach , assuming instantaneous interactions in the superfluid phase .
a comparison with the results obtained from several hadronic field models is made .
main characteristics of our description of the superfluid gap are in qualitative agreement with some studies using microscopic potentials , although further refinements could improve its performance . .
And you have already written the first three sentences of the full article: superfluid states in the nuclear environment have been extensively studied as they have a significative role in several physical processes , such as the structure of nuclei out the stability valley and the cooling dynamics of proto - neutron stars . + a variety of models and approximations
have been used for this purpose @xcite , mainly non - relativistic potentials or effective forces , such as the density - dependent skyrme or gogny ones .
it is not unusual a mixed treatment that combines both schemes in order to simplify involved calculations @xcite ..
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+ approximately two decades ago a covariant model of the field theory of hadrons , generally known as quantum hadro - dynamics ( qhd ) @xcite , was used for the first time to study nuclear matter superfluidity @xcite .
there are several reasons to use this theoretical framework to deal with nuclear superfluidity , in first place there are practical reasons , some self - consistent calculations are more simply stated and easily solved .
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Suppose that you have an abstract for a scientific paper: we report the first high angular resolution imaging ( 3.4@xmath0 3.0 ) of deuterated formaldehyde ( hdco ) toward orion
kl , carried out with the submillimeter array ( sma ) .
we find that the spatial distribution of the formaldehyde emission systematically differs from that of methanol : while methanol is found towards the inner part of the region , hdco is found in colder gas that wraps around the methanol emission on four sides .
the hdco / h@xmath1co ratios are determined to be 0.0030.009 within the region , up to an order of magnitude higher than the d / h measured for methanol .
these findings strengthen the previously suggested hypothesis that there are differences in the chemical pathways leading to hdco ( via deuterated gas phase chemistry ) and deuterated methanol ( through conversion of formaldehyde into methanol on the surface of icy grain mantles ) . .
And you have already written the first three sentences of the full article: the orion kl nebula , that lies at a distance of 414@xmath27 pc @xcite is a focal source for studies of the physics and chemistry of high mass star forming regions .
its rich molecular diversity and complex physical structure have been revealed by a number of spectral line surveys and interferometric studies of the region ( e.g. * ? ? ?
* ; * ? ? ?.
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* ; * ? ? ?
* ; * ? ? ?
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Suppose that you have an abstract for a scientific paper: we calculate the sivers function in semi - inclusive deep inelastic scattering ( sidis ) and in the drell - yan process ( dy ) by employing the quasi - classical glauber mueller/ mclerran venugopalan approximation . modeling the hadron as a large `` nucleus '' with non - zero orbital angular momentum ( oam )
, we find that its sivers function receives two dominant contributions : one contribution is due to the oam , while another one is due to the local sivers function density in the nucleus .
while the latter mechanism , being due to the `` lensing '' interactions , dominates at large transverse momentum of the produced hadron in sidis or of the di - lepton pair in dy , the former ( oam ) mechanism is leading in saturation power counting and dominates when the above transverse momenta become of the order of the saturation scale .
we show that the oam channel allows for a particularly simple and intuitive interpretation of the celebrated sign flip between the sivers functions in sidis and dy .
+ pacs numbers : 12.38.bx , 13.88.+e , 12.38.cy , 24.85.+p .
And you have already written the first three sentences of the full article: single transverse spin asymmetries ( stsas ) generated in semi - inclusive deep inelastic scattering ( sidis ) and in hadronic collisions are one of the hot topics of research in quantum chromodynamics ( qcd ) , promising unparalleled insight in the physics of chiral symmetry breaking and quark confinement . in the factorization framework involving transverse momentum - dependent distribution functions ( tmds ) @xcite the origin of stsas
is chiefly ascribed to either the quark tmds ( sivers effect @xcite ) , to multiple partonic rescattering @xcite , or to the quark fragmentation functions ( collins effect @xcite ) . while both the quark tmd and the fragmentation function are non - perturbative , and , according to the conventional wisdom , can not be calculated form first principles , it is desirable to understand the detailed physical mechanism leading to generation of stsas in qcd . to that end
a significant progress has been achieved by brodsky , hwang and schmidt ( bhs ) in @xcite ( see also @xcite ) , where , in a quark di - quark proton model calculation , it has been shown that the stsa in sidis can be generated through an interference of the final - state parton rescattering diagram with the born - level amplitude ..
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in essence , it was shown in @xcite that multiple partonic rescatterings are key to generating the asymmetry .
the multiple rescatterings are often referred to as the `` lensing '' interaction , since , in sidis , the associated color - lorentz force tries to attract the knocked - out quarks back into the hadron @xcite , thus `` focusing '' them .
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Suppose that you have an abstract for a scientific paper: disordered hyperuniform many - particle systems have attracted considerable recent attention , since they behave like crystals in the manner in which they suppress large - scale density fluctuations , and yet also resemble statistically isotropic liquids and glasses with no bragg peaks .
one important class of such systems is the classical ground states of `` stealthy potentials . ''
the degree of order of such ground states depends on a tuning parameter @xmath0 .
previous studies have shown that these ground - state point configurations can be counterintuitively disordered , infinitely degenerate , and endowed with novel physical properties ( e.g. , negative thermal expansion behavior ) . in this paper , we focus on the disordered regime ( @xmath1 ) in which there is no long - range order , and control the degree of short - range order .
we map these stealthy disordered hyperuniform point configurations to two - phase media by circumscribing each point with a possibly overlapping sphere of a common radius @xmath2 : the `` particle '' and `` void '' phases are taken to be the space interior and exterior to the spheres , respectively .
the hyperuniformity of such two - phase media depend on the sphere sizes : while it was previously analytically proven that the resulting two - phase media maintain hyperuniformity if spheres do not overlap , here we show numerically that they lose hyperuniformity whenever the spheres overlap .
we study certain transport properties of these systems , including the effective diffusion coefficient of point particles diffusing in the void phase as well as static and time - dependent characteristics associated with diffusion - controlled reactions . besides these effective transport properties
, we also investigate several related structural properties , including pore - size functions , quantizer error , an order metric , and percolation thresholds .
we show that these transport , geometrical and topological properties of our two - phase media derived from....
And you have already written the first three sentences of the full article: a hyperuniform many - particle system is one in which the structure factor approaches zero in the infinite - wavelength limit.@xcite in such systems , density fluctuations ( measured by the variance of number of particles inside a spherical window ) are anomalously suppressed at very large lengths scales , a `` hidden '' order that imposes strong global structural constraints.@xcite all structurally perfect crystals and quasicrystals are hyperuniform,@xcite but typical disordered many - particle systems , including gases , liquids , and glasses , are not .
disordered hyperuniform many - particle systems are exotic states of amorphous matter that have attracted considerable recent attention.@xcite materials that are simultaneously disordered and hyperuniform can be regarded to be exotic states of matter that lie between a crystal and a liquid ; they behave more like crystals in the manner in which they suppress large - scale density fluctuations , and yet they also resemble typical statistically isotropic liquids and glasses with no bragg peaks.@xcite an important class of disordered hyperuniform many - particle systems is comprised of the classical ground states of `` stealthy potentials,''@xcite which are bounded , long - range , pairwise additive potentials designed in fourier space .
these classical ground states are of particular fundamental interest because they can be degenerate and noncrystalline ..
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a nonnegative parameter inversely proportional to the number density , @xmath0 , controls the degree of order of such ground states . for @xmath4 ,
the ground states are overwhelmingly highly degenerate and disordered .
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Suppose that you have an abstract for a scientific paper: two - level quantum systems , qubits , are not the only basis for quantum computation .
advantages exist in using qudits , @xmath0-level quantum systems , as the basic carrier of quantum information .
we show that color codes a class of topological quantum codes with remarkable transversality properties can be generalized to the qudit paradigm . in recent developments
it was found that in three spatial dimensions a qubit color code can support a transversal non - clifford gate , and that in higher spatial dimensions additional non - clifford gates can be found , saturating bravyi and knig s bound [ phys .
rev .
lett . * 110 * , 170503 ( 2013 ) ] .
furthermore , by using gauge fixing techniques , an effective set of clifford gates can be achieved , removing the need for state distillation .
we show that the qudit color code can support the qudit analogues of these gates , and show that in higher spatial dimensions a color code can support a phase gate from higher levels of the clifford hierarchy which can be proven to saturate bravyi and knig s bound in all but a finite number of special cases .
the methodology used is a generalisation of bravyi and haah s method of triorthogonal matrices [ phys .
rev .
a * 86 * 052329 ( 2012 ) ] , which may be of independent interest . for completeness
, we show explicitly that the qudit color codes generalize to gauge color codes , and share the many of the favorable properties of their qubit counterparts . .
And you have already written the first three sentences of the full article: quantum technologies are often developed in the qubit paradigm , where the basic carrier of quantum information is a two - level quantum system .
qubits are a natural choice because binary is the language of classical technologies .
however , even here , despite the prevalence of binary , its supremacy is questionable ..
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indeed , donald knuth has advocated the use of balanced ternary , a 3-state classical logic @xcite . in the quantum domain ,
qudits offer a state space with a richer structure than their two - level counterparts , and the merits of this for quantum information have been explored in many contexts @xcite .
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Suppose that you have an abstract for a scientific paper: we study projective - anticipating , projective , and projective - lag synchronization of time - delayed chaotic systems on random networks .
we relax some limitations of previous work , where projective - anticipating and projective - lag synchronization can be achieved only on two coupled chaotic systems . in this paper
, we can realize projective - anticipating and projective - lag synchronization on complex dynamical networks composed by a large number of interconnected components . at the same time , although previous work studied projective synchronization on complex dynamical networks , the dynamics of the nodes are coupled partially linear chaotic systems . in this paper , the dynamics of the nodes of the complex networks are time - delayed chaotic systems without the limitation of the partial - linearity . based on the lyapunov stability theory ,
we suggest a generic method to achieve the projective - anticipating , projective , and projective - lag synchronization of time - delayed chaotic systems on random dynamical networks and find both the existence and sufficient stability conditions . the validity of the proposed method is demonstrated and verified by examining specific examples using ikeda and mackey - glass systems on erds - rnyi networks .
+ + _ pacs _ : 05.45.xt , 05.45.jn , 89.75.hc + + _ keywords _ : projective - anticipating synchronization ; projective synchronization ; projective - lag synchronization ; time - delayed chaotic systems ; complex networks * * in 1999 , mainieri and rehacek observed projective synchronization in coupled partially linear chaotic systems where the drive and response vectors synchronize up to a constant ratio @xmath0 ( scaling factor ) .
complete synchronization and anti - phase synchronization are proved to be the special cases of projective synchronization in cases of @xmath1 and @xmath2 , respectively .
this proportional feature can be used to extend binary digital to m - nary digital for achieving fast communication . with the....
And you have already written the first three sentences of the full article: chaos synchronization has attracted considerably increasing attention and become an active area of research for both theoretical interests and practical applications , since seminal work of pecora and carroll @xcite . over the last decade , following the complete synchronization @xcite , several new types of synchronization have been found in interacting chaotic systems , such as generalized synchronization @xcite , phase synchronization @xcite , anti - phase synchronization @xcite , projective synchronization @xcite , lag synchronization @xcite and anticipating synchronization @xcite .
complete synchronization is characterized by the convergence of the two chaotic trajectories , @xmath3 .
it appears only when interacting systems are identical ..
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generalized synchronization means the amplitude of the slave s state variable correlated with that of master s by a generic function , @xmath4 .
phase synchronization is defined as the entrainment of phases of chaotic oscillators , @xmath5 ( @xmath6 and @xmath7 are integers ) , whereas their amplitude remains chaotic and uncorrelated .
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Suppose that you have an abstract for a scientific paper: in@xmath0mn@xmath1as diluted magnetic semiconductor ( dms ) thin films have been grown using metalorganic vapor phase epitaxy ( movpe ) .
tricarbonyl(methylcyclopentadienyl)manganese was used as the mn source . nominally single - phase , epitaxial films were achieved with mn content as high as @xmath2 using growth temperatures @xmath3 @xmath4c . for lower growth temperatures and higher mn concentrations , nanometer scale mnas precipitates were detected within the in@xmath0mn@xmath5as matrix .
magnetic properties of the films were investigated using a superconducting quantum interference device ( squid ) magnetometer .
room - temperature ferromagnetic order was observed in a sample with @xmath6 .
magnetization measurements indicated a curie temperature of 333 k and a room - temperature saturation magnetization of 49 emu/@xmath7 .
the remnant magnetization and the coercive field were small , with values of 10 emu/@xmath7 and 400 oe , respectively .
a mechanism for this high - temperature ferromagnetism is discussed in light of the recent theory based on the formation of small clusters of a few magnetic atoms . .
And you have already written the first three sentences of the full article: an approach to spin - sensitive devices for electronic applications , that may exhibit improved spin injection , is the use of iii - v diluted magnetic semiconductors ( dmss).@xcite these alloys , which incorporate a small percentage of magnetic atoms into the semiconductor host , have been shown to exhibit ferromagnetic behavior up to 110 k.@xcite however , for these materials to find widespread applications , the ferromagnetism should be stable at room temperature .
consequently , much of the current experimental work is directed towards increasing their ferromagnetic transition temperature , @xmath8 . since theory predicts that the transition temperature increases with the magnetic - ion concentration ,
efforts have centered on increasing such concentration.@xcite the solubility of magnetic ions , however , is often quite low ..
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iii - v dms have been grown using low - temperature molecular beam epitaxy ( lt - mbe ) at temperatures lower than 300 @xmath4c to prevent phase separation .
nevertheless , recently we have demonstrated the growth of single - phase , ferromagnetic in@xmath0mn@xmath1as , with @xmath9 , using metalorganic vapor phase epitaxy ( movpe ) at temperatures as high as 520 @xmath4c.@xcite in this report , we present the results of our investigation of the magnetic properties of these films .
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Suppose that you have an abstract for a scientific paper: new spectroscopic observations show that the double degenerate system nltt 16249 is in a close orbit ( @xmath0 ) with a period of 1.17 d. the total mass of the system is estimated between 1.47 and 2.04@xmath1 but it is not expected to merge within a hubble time - scale ( @xmath2 yr ) .
vennes & kawka ( 2012 , apj , 745 , l12 ) originally identified the system because of the peculiar composite hydrogen ( da class ) and molecular ( c@xmath3dq class and cn ) spectra and the new observations establish this system as the first da plus dq close double degenerate . also , the dq component was the first of its class to show nitrogen dredged - up from the core in its atmosphere
. the star may be viewed as the first known dq descendant of the born - again pg1159 stars .
alternatively , the presence of nitrogen may be the result of past interactions and truncated evolution in a close binary system . .
And you have already written the first three sentences of the full article: the high - proper motion star nltt 16249 is a double degenerate system showing hydrogen lines and molecular carbon and cyanogen bands in its optical spectrum @xcite .
although large radial velocity variations were noted by @xcite , the orbital parameters , period and separation , are yet to be determined .
the detection of photospheric nitrogen in the carbon - rich ( dq ) component of this system was a first occurrence for this class of objects and , according to the dredge - up scenario commonly applied to dq white dwarfs @xcite , it implied the presence of nitrogen in the white dwarf core ..
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the other component is a hydrogen - rich ( da ) white dwarf with a mass above average but with a luminosity similar to that of the dq white dwarf .
the two characteristics of the system , a nitrogen - enriched dq component and a likely close orbit , may or may not be related .
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10,250 |
Suppose that you have an abstract for a scientific paper: if dark matter ( dm ) has non - zero direct or transition , electric or magnetic dipole moment then it can scatter nucleons electromagnetically in direct detection experiments . using the results from experiments like xenon , cdms , dama and cogent we put bounds on the electric and magnetic dipole moments of dm .
if dm consists of dirac fermions with direct dipole moments , then dm of mass less than 10 gev is consistent with the dama signal and with null results of other experiments .
if on the other hand dm consists of majorana fermions then they can have only non - zero transition moments between different mass eigenstates .
we find that majorana fermions with mass @xmath0 gev and mass splitting of the order of ( 50 - 200 ) kev can explain the dama signal and the null observations from other experiments and in addition give the observed relic density of dm by dipole - mediated annihilation .
this parameter space for the mass and for dipole moments is allowed by limits from l3 but may have observable signals at lhc .
2.5 cm + 0.5 cm @xmath1_grup de fsica terica and institut de fsica daltes energies + universitat autnoma de barcelona , 08193 bellaterra , spain _ + @xmath2_physical research laboratory ,
ahmedabad 380009 , india _ + .
And you have already written the first three sentences of the full article: experimental observations mainly of dynamics of spiral galaxies and galaxy clusters indicate the existence of dark matter ( dm ) .
cosmological observations confirm the existence of dm and in addition show that the bulk of it must be non - baryonic @xcite . in this paper
we consider weakly interacting massive particles ( wimps ) as candidates for dm , but we adopt a model independent and phenomenological approach ..
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the mass and cross section of the dm ( which is expected to have a local density of about 0.3 gev/@xmath3 and velocity w.r.t the earth of about 200 km / sec @xcite ) is probed by direct detection experiments like xenon @xcite , cdms @xcite , dama @xcite and cogent @xcite .
these experiments detect dm scattering off nuclei by measuring the recoil energy of the nuclei .
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10,251 |
Suppose that you have an abstract for a scientific paper: beam power is a fundamental parameter that describes , in part , the state of a supermassive black hole system .
determining the beam powers of powerful classical double radio sources requires substantial observing time , so it would be useful to determine the relationship between beam power and radio power so that radio power could be used as a proxy for beam power .
a sample of 31 powerful classical double radio sources with previously determined beam and radio powers are studied ; the sources have redshifts between about 0.056 and 1.8 .
it is found that the relationship between beam power , @xmath0 , and radio power , @xmath1 , is well described by @xmath2 , where both @xmath0 and @xmath1 are in units of @xmath3 .
this indicates that beam power is converted to radio power with an efficiency of about 0.7% .
the ratio of beam power to radio power is studied as a function of redshift ; there is no significant evidence for redshift evolution of this ratio over the redshift range studied .
the relationship is consistent with empirical results obtained by cavagnolo et al .
( 2010 ) for radio sources in gas rich environments , which are primarily fri sources , and with the theoretical predictions of willott et al .
( 1999 ) .
[ firstpage ] black hole physics galaxies : active .
And you have already written the first three sentences of the full article: a powerful classical double radio source , also known as an frii source ( fanaroff & riley 1974 ) , is powered by large scale outflows from a supermassive black hole system that resides at the center of a galaxy ( e.g. blandford & rees 1974 ; scheuer 1974 ) .
the energy per unit time , or beam power , carried from the vicinity of the supermassive black hole to the large scale radio source is a fundamental physical parameter that , in part , describes the physical state of the black hole system .
the beam power can be used to study many aspects of the source , the source population , interactions of the source with its environment , and the role of feedback between the black hole system , its environment , and the host galaxy ( e.g. silk & rees 1998 ; willott et al ..
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1999 ; eilek & owen 2002 ; birzan et al .
2004 ; croston et al . 2005 ; dunn et al . 2005 ; dunn & fabian 2006 ; rafferty et al .
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10,252 |
Suppose that you have an abstract for a scientific paper: in paul , raichur and mukherjee ( 2005 ) we had reported a spectral mode change in the x - ray binary pulsar cen x-3 using the then available asm light curves of cen x-3 .
being mindful of the fact that instrument calibration or other issues like gain changes , software issues etc . might give rise to some of the artifacts , we had used the asm light curves of three other x - ray binary pulsars namely her x-1 , smc x-1 and vela x-1 for comparison for the same observation times . in light of the recent
finding of mller et al .
( 2011 ) ; which reports the non - detection of such features in the current asm light curves available on the heasarc website and with other instruments like maxi , swift and integral , we would like to point out the inconsistency between the asm ligthcurves available in 2005 and now .
this information will be very useful for other users of asm light curves . .
And you have already written the first three sentences of the full article: using multi - band light curve of the rxte - asm , we had reported a significant change in the x - ray spectrum of cen x-3 in the period december 2000 to april 2004 .
this was interpreted as a change in the accretion mode in this period ( paul , raichur & mukherjee , 2005 ) .
recently , mller et al . ( 2011 ) reported non detection of this feature in the rxte - asm light curve of the same time span and also in some additional data from rxte - asm , maxi , integral and swift ..
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we fully agree with the findings of mller et al .
( 2011 ) here we report that the earlier finding was not due to any error in analysis of the light curves used in paul , raichur & mukherjee ( 2005 ) but due to a discrepancy in the asm light curve for the same period that was made available in 2005 and what is available now .
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10,253 |
Suppose that you have an abstract for a scientific paper: we obtain new closed - form pricing formulas for contingent claims when the asset follows a dupire - type local volatility model . to obtain the formulas we use the dyson - taylor commutator method that we have recently developed in @xcite for short - time asymptotic expansions of heat kernels , and obtain a family of general closed - form approximate solutions for both the pricing kernel and derivative price .
a bootstrap scheme allows us to extend our method to large time .
we also perform analytic as well as a numerical error analysis , and compare our results to other known methods . .
And you have already written the first three sentences of the full article: financial derivatives ( also known as contingent claims ) are now a ubiquitous tool in risk management with approximately 600 trillion dollars worth of such contracts currently in the market .
the pricing of such derivatives is therefore an active area of research in both mathematics and finance ( see for example @xcite and the references therein ) . in this paper
, we will apply the perturbative ( asymptotic ) method introduced in @xcite for numerically solving parabolic equations and then use this method to price european options ..
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one of the earliest models used in pricing derivatives is the black - scholes - merton model @xcite , for which the movement in the price @xmath0 of the underlying asset on which the claim is based is modeled by geometric brownian motion . for the black - scholes - merton as well as for other models given by stochastic differential equations
, the pricing of european options can be reduced to the calculation of certain solutions of parabolic equations , obtained through ito s lemma ( and the change of variables @xmath1 ) in the backward kolmogorov equation .
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10,254 |
Suppose that you have an abstract for a scientific paper: we have experimentally investigated field induced aggregation of nonmagnetic particles confined in a magnetic fluid layer when rotating magnetic fields were applied . after application of a magnetic field rotating in the plane of the fluid layer , the single particles start to form two - dimensional ( 2d ) clusters , like doublets , triangels , and more complex structures .
these clusters aggregated again and again to form bigger clusters . during this nonequilibrium process
, a broad range of cluster sizes was formed , and the scaling exponents , @xmath0 and @xmath1 , of the number of clusters @xmath2and average cluster size @xmath3 were calculated .
the process could be characterized as diffusion limited cluster - cluster aggregation .
we have found that all sizes of clusters that occured during an experiment , fall on a single curve as the dynamic scaling theory predicts .
hovewer , the characteristic scaling exponents @xmath4 and crossover exponents @xmath5 were not universal .
a particle tracking method was used to find the dependence of the diffusion coefficients @xmath6 on cluster size @xmath7 .
the cluster motions show features of _ _ brownian _ _ motion .
the average diffusion coefficients @xmath8 depend on the cluster sizes @xmath7 as a power law @xmath9 where values of @xmath10 as different as @xmath11 and @xmath12 were found in two of the experiments . .
And you have already written the first three sentences of the full article: colloidal aggregation phenomena are intersting subjects of study for both theoretical and technological reasons . in systems with short range interactions the main aggregation features
are well understood @xcite .
diffusion limited cluster - cluster aggregation ( cca ) model @xcite and dynamic scaling theory @xcite explain well the scaling properties during aggregation ..
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it was found that these models , initialy developed for systems with short range interactions , can be used in systems where dipole - dipole interaction is dominant , for example aggregation of magnetic microspheres @xcite , aggregation of nanoparticles in magnetic fluid @xcite and aggregation of magnetic holes @xcite .
these experimental results show scaling of the significant parameters and features typical of cca . on the other hand
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Suppose that you have an abstract for a scientific paper: we investigate the discretized version of the compact randall - sundrum model . by studying the mass eigenstates of the lattice theory ,
we demonstrate that for warped space , unlike for flat space , the strong coupling scale does not depend on the ir scale and lattice size .
however , strong coupling does prevent us from taking the continuum limit of the lattice theory .
nonetheless , the lattice theory works in the manifestly holographic regime and successfully reproduces the most significant features of the warped theory .
it is even in some respects better than the kk theory , which must be carefully regulated to obtain the correct physical results .
because it is easier to construct lattice theories than to find exact solutions to gr , we expect lattice gravity to be a useful tool for exploring field theory in curved space .
ucb - pth-05/18 + lbnl-57913 + * discretizing gravity in warped spacetime * lisa randall@xmath0 , matthew d. schwartz@xmath1 , and shiyamala thambyahpillai@xmath0 + .
And you have already written the first three sentences of the full article: warped geometries , such as the background used in randall - sundrum model @xcite , have provided many insights into general relativity and holography
. however , it is very difficult to find exact solutions to einstein s equations , so only a handful of warped geometries are known . it would be useful to have a tool for constructing theories that reproduce the features of the warped geometries without having to find and stabilize an appropriate gravitational source .
discrete gravitational dimensions could be such a tool @xcite ..
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if we work in the effective field theory framework with a cutoff , we may be able to learn a lot about general realtivity without needing exact solutions , as long as the discrete theory can be trusted .
of course , this will not tell us about the energy - momentum tensor to generate such a background , but we can use the discrete model as a tool for investigating stability of the system , the existence of ghosts , and the strong coupling scale , for example . in this paper , we study the the discretization of a single extra dimension in which we impose the exponential warp factor of the randall - sundrum model . although previous work discussed discrete nongravitational extra dimensions for rs @xcite , so far gravity has not been included in the discretized model .
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10,256 |
Suppose that you have an abstract for a scientific paper: we present an interpretation of zero field diffuse neutron scattering and of high field magnetisation data at very low temperature in the frustrated pyrochlore system tb@xmath0ti@xmath0o@xmath1 .
this material has antiferromagnetic exchange interactions and it is expected to have ising character at low temperature .
contrary to expectations , it shows no magnetic ordering down to 0.05k , being thus labelled a `` spin liquid '' .
however , the ground state in tb@xmath0ti@xmath0o@xmath1 is not a mere fluctuating moment paramagnet but , as demonstrated by very recent experiments , a state where the electronic degrees of freedom are hybridised with the phononic variables in an unconventional way .
we show here that , by approximating this complex and still unraveled electron - phonon interaction by a dynamic jahn - teller coupling , one can account rather well for the diffuse neutron scattering and the low temperature isothermal magnetisation .
we discuss the shortcomings of this picture which arise mainly from the fact that the singlet electronic mean field ground state of the model fails to reproduce the observed strong intensity of the elastic and quasi - elastic neutron scattering . .
And you have already written the first three sentences of the full article: the pyrochlore titanates , with formula r@xmath0ti@xmath0o@xmath1 where r is a rare earth , have been the subject of experimental and theoretical studies for more than a decade @xcite .
the pyrochlore lattice where the r@xmath2 ( and the ti@xmath3 ) ions are located is formed by corner - sharing tetrahedra and leads indeed to a frustration of the exchange / dipolar interaction in some specific situations .
the best known consequence thereof is the existence of `` spin - ice '' materials , like ho@xmath0ti@xmath0o@xmath1 and dy@xmath0ti@xmath0o@xmath4 @xcite , where the rare earth moments have a strong ising character along the tetrahedron ternary axis ..
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the spin - ices remain in the paramagnetic phase down to the lowest attainable temperature , but the spin correlations are very strong and of the special `` two in - two out '' type , i.e. where two rare earth moments point `` outwards '' a given tetrahedron and two inwards . the excitations in spin - ices have been shown to be magnetic monopole quasi - particles @xcite . another pyrochlore material which remains paramagnetic down to at least 0.05k is tb@xmath0ti@xmath0o@xmath1 @xcite . the tb@xmath2 ion is a non - kramers ion with @xmath5=6 and a land factor @xmath6=3/2 . it is submitted to a trigonal symmetry crystal electric field ( cef ) which lifts the 13-fold degeneracy of the @xmath5=6 multiplet .
the peculiarity of the crystal field splitting in tb@xmath0ti@xmath0o@xmath1 has been early recognised @xcite , as consisting of two ground magnetic doublets separated by an energy of the order of 15k . for a non - kramers ion , each such doublet \{@xmath7 }
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10,257 |
Suppose that you have an abstract for a scientific paper: we combine linear and non - linear optical spectroscopy at 4 k with ab initio calculations to study the electronic bandstructure of mose@xmath0 monolayers . in 1-photon photoluminescence excitation ( ple ) and
reflectivity we measure a separation between the a- and b - exciton emission of 220 mev . in 2-photon ple
we detect for the a- and b - exciton the 2p state 180 mev above the respective 1s state . in second harmonic generation ( shg )
spectroscopy we record an enhancement by more than 2 orders of magnitude of the shg signal at resonances of the charged exciton and the 1s and 2p neutral a- and b - exciton .
our post - density functional theory calculations show in the conduction band along the @xmath1 direction a local minimum that is energetically and in k - space close to the global minimum at the k - point .
this has a potentially strong impact on the polarization and energy of the excitonic states that govern the interband transitions and marks an important difference to mos@xmath0 and wse@xmath0 monolayers . .
And you have already written the first three sentences of the full article: ( a ) conduction ( cb ) and valence states ( vb ) in a single particle picture . ( b )
the intensity of the neutral 1s a - exciton pl ( shown as gray solid line ) is recorded as a function of laser energy . in 1-photon ple ( red circles ) the 1s b - exciton state ( x@xmath2 ) is identified , in 2-photon ple ( open black squares ) the peaks
are assigned to the 2p a - exciton ( x@xmath3 ) and 2p b - exciton ( x@xmath4 ) ..
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( c ) maxima of the first derivative of the reflectivity allow to assign the 1s a - exciton and b - exciton state energies .
, scaledwidth=47.0% ] monolayers ( mls ) of the transition metal dichalcogenides ( tmdcs ) mos@xmath0 , mose@xmath0 , ws@xmath0 and wse@xmath0 ( abbreviated mx@xmath0 ) are semiconductors with a direct bandgap in the visible region @xcite .
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10,258 |
Suppose that you have an abstract for a scientific paper: fuse spectroscopy has proved that extremely hot hydrogen - deficient post - agb stars ( pg1159 stars ) display matter on their surface that usually remains hidden in the region between the h- and he - burning shells of the former agb star .
hence , the spectral analysis of pg1159 stars allows to study directly the chemistry of this intershell region which is the outcome of complicated burning and mixing processes during agb evolution .
detailed abundance determinations provide constraints for these processes which are still poorly understood . with fuse
we have discovered high neon and fluorine overabundances . there is also a significant iron deficiency , which may be caused by s - process neutron capture transforming iron into heavier elements . .
And you have already written the first three sentences of the full article: pg1159 stars are hot hydrogen - deficient ( pre- ) white dwarfs ( @xmath0 between 75000 and 200000k , @xmath1=5.58 ; werner 2001 ) .
they are probably the outcome of a late he - shell flash , a phenomenon that drives the currently observed fast evolutionary rates of three well - known objects ( fg sge , sakurai s object , v605 aql ) .
flash - induced envelope mixing produces a h - deficient stellar surface ( herwig etal ..
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the photospheric composition then essentially reflects that of the region between the h- and he - burning shells in the precursor agb star .
the he - shell flash transforms the star back to an agb star ( `` born - again agb star '' ) and the subsequent , second post - agb evolution explains the existence of wolf - rayet central stars of planetary nebulae and their successors , the pg1159 stars .
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10,259 |
Suppose that you have an abstract for a scientific paper: let @xmath0 be a topologically finite , orientable 3manifold with ideal triangulation . we show that if there is a solution to the hyperbolic gluing equations , then all edges in the triangulation are essential .
this result is extended to a generalisation of the hyperbolic gluing equations , which enables the construction of hyperbolic cone - manifold structures on @xmath0 with singular locus contained in the 1skeleton of the triangulation . .
And you have already written the first three sentences of the full article: neumann and zagier @xcite study the variation of the volume function on a cusped hyperbolic 3manifold of finite volume using a decomposition of the manifold into hyperbolic ideal tetrahedra .
this is based on a construction by thurston @xcite , which associates to the underlying topological ideal triangulation a
_ parameter space _ of shapes of ideal hyperbolic tetrahedra satisfying certain polynomial equations ..
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such a parameter space can be associated to any ideal triangulation of a non - compact 3-manifold with torus cusps , and several authors have studied this affine algebraic set in this generality ( see , for instance , yoshida @xcite , francaviglia @xcite , tillmann @xcite , segerman @xcite ) . a key step in many applications is the construction of a so - called pseudo - developing map for a given point on the parameter space in order to produce a representation of the fundamental group of the manifold into the group of orientation preserving isometries of hyperbolic 3space .
the map is called a pseudo - developing map rather than a developing map because it is not necessarily locally injective .
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Suppose that you have an abstract for a scientific paper: it is well known that non - ideal magnetohydrodynamic effects are important in the dynamics of molecular clouds : both ambipolar diffusion and possibly the hall effect have been identified as significant .
we present the results of a suite of simulations with a resolution of @xmath0 of turbulent decay in molecular clouds incorporating a simplified form of both ambipolar diffusion and the hall effect simultaneously .
the initial velocity field in the turbulence is varied from being super - alfvnic and hypersonic , through to trans - alfvnic but still supersonic .
we find that ambipolar diffusion increases the rate of decay of the turbulence increasing the decay from @xmath1 to @xmath2 .
the hall effect has virtually no impact in this regard .
the power spectra of density , velocity and the magnetic field are all affected by the non - ideal terms , being steepened significantly when compared with ideal mhd turbulence with exponents .
the density power spectra components change from @xmath3 to @xmath4 for the ideal and non - ideal simulations respectively , and power spectra of the other variables all show similar modifications when non - ideal effects are considered .
again , the dominant source of these changes is ambipolar diffusion rather than the hall effect .
there is also a decoupling between the velocity field and the magnetic field at short length scales .
the hall effect leads to enhanced magnetic reconnection , and hence less power , at short length scales .
the dependence of the velocity dispersion on the characteristic length scale is studied and found not to be power - law in nature . .
And you have already written the first three sentences of the full article: the role of turbulence in molecular cloud evolution has been a subject of much study in the literature ( see , for example , the excellent reviews of @xcite ) . observations of the properties of gas and dust motions in molecular clouds @xcite suggest that , indeed , turbulence is present .
it is clear that turbulent motion could influence the star formation rate and efficiency as well as the initial mass function @xcite . given all this there are several interesting questions which arise : 1 .
what is the source of molecular cloud turbulence ?.
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how fast does it decay ?
3 . how does it affect star formation ? 4 .
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10,261 |
Suppose that you have an abstract for a scientific paper: i re - examine the brightness temperature problem in pks 0405 - 385 which is
an extreme intra - day variable radio quasar with an inferred brightness temperature of @xmath0 k at 5 ghz , well above the compton catastrophe limit of @xmath1 k reached when the synchrotron photon energy density exceeds the energy density of the magnetic field .
if one takes into account the uncertainty in the distance to the ionized clouds responsible for interstellar scintillation causing rapid intra - day variability in pks 0405 - 385 it is possible that the brightness temperature could be as low as @xmath2 k at 5 ghz , or even lower .
the radio spectrum can be fitted by optically thin emission from mono - energetic electrons , or an electron spectrum with a low - energy cut - off such that the critical frequency of the lowest energy electrons is above the radio frequencies of interest .
if one observes optically thin emission along a long narrow emission region , the average energy density in the emission region can be many orders of magnitude lower than calculated from the observed intensity if one assumed a spherical emission region .
i discuss the physical conditions in the emission region and find that the compton catastrophe can then be avoided using a reasonable doppler factor .
i also show that mev to 100 gev gamma - ray emission at observable flux levels should be expected from extreme intra - day variable sources such as pks 0405 - 385 .
galaxies : active galaxies : jets gamma - rays : theory radiation mechanisms : non - thermal quasars : pks 0405 - 385 . .
And you have already written the first three sentences of the full article: rapid variability in intra - day variable ( idv ) sources is a long - standing problem as it implies apparent brightness temperatures in the radio regime which may exceed 10@xmath3 k , or requires relativistic beaming with extremely high doppler factors , coherent radiation mechanisms , or special geometric effects ( wagner & witzel 1995 ) . such high brightness temperatures would be well above the `` compton catastrophe '' limit @xmath4 k imposed by inverse - compton scattering ( kellermann & paulini - toth 1969 , slysh 1992 , kardashev 2000 ) when the photon energy density in the emission region exceeds the energy density in the magnetic field .
see krichbaum et al.(2002 ) and kedziora - chudczer et al .
( 2001 ) for recent reviews of idv sources ..
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the radio - loud quasar pks 0405 - 385 is an extreme example of an intra - day variable source with variations on timescales of @xmath5 d ( kedziora - chudczer et al .
1997 ) . making the assumption that the emission region subtends solid angle @xmath6 , where @xmath7 is the doppler factor and @xmath8 is the diameter distance to the source
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10,262 |
Suppose that you have an abstract for a scientific paper: we suggested a monte carlo approach to simulate a kinetic equilibrium ensemble , and proved the equivalence to the linear equations method on equilibrium . with the convenience of the numerical method
, we introduced variable splitting rates representing the details of the dynamics as model parameters which were not considered in previous works .
the dependence on model parameters was studied , and it was found that the sea quark flavor asymmetry weakly depends on model parameters .
it reflects the statistics principle contributes the dominant part of the asymmetry and the effect caused by details of the dynamics is small .
we also applied the monte carlo approach of the statistical model to predict the theoretical sea quark asymmetries in kaons , octet baryons @xmath0 , @xmath1 , and @xmath2 baryons , even in exotic pentaquark states . .
And you have already written the first three sentences of the full article: although the proton is the simplest system in which the three colors of qcd neutralize into a colorless bound state , we still do not know how to describe the proton in terms of its fundamental quark and gluon degrees of freedom from basic principles .
the structure of the proton is rather complicated due to the nonperturbative and relativistic nature of the quark and gluon in the protons .
the complication also comes from the presence of sea quarks in the proton ..
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the sea flavor symmetry naively assumed in the gottfried sum rule @xcite , which is a symmetry between the light flavor @xmath3 and @xmath4 sea quarks inside the proton , was disproved by experiments of both deep inelastic scattering and drell - yan processes @xcite .
many theoretical attempts have been made to describe the origin of the nucleon sea and its antiquark asymmetry @xcite .
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10,263 |
Suppose that you have an abstract for a scientific paper: extensive simulations are made on the bimodal ising spin glass ( isg ) in dimension four .
the transition temperature is established using a combination of standard finite size scaling and of thermodynamic derivative peak data .
measurements in the thermodynamic limit regime are analysed so as to estimate critical exponents and confluent correction terms .
comparisons with results on other @xmath0d isgs show that the susceptibility and correlation length critical exponents @xmath1 and @xmath2 depend on the form of the interaction distribution . from this observation
it can be deduced that critical exponents are not universal in isgs . .
And you have already written the first three sentences of the full article: the universality of critical exponents is an important and remarkably elegant property of standard second order transitions , which has been explored in great detail through the renormalization group theory ( rgt ) .
the universality hypothesis states that for all systems within a universality class the critical exponents are rigorously identical and do not depend on the microscopic parameters of the model
. however , universality is not strictly universal ; there are known eccentricmodels which are exceptions and violate the universality rule in the sense that their critical exponents vary continuously as functions of a control variable ..
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the most famous example is the eight vertex model solved exactly by baxter @xcite ; there are other scattered cases , all in dimension two as far as we are aware . for ising spin glasses ( isgs ) ,
the form of the interaction distribution is a microscopic control parameter .
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10,264 |
Suppose that you have an abstract for a scientific paper: thermoelectric coefficients of an ultra - thin topological insulator are presented here .
the hybridization between top and bottom surface states of a topological insulator plays a significant role . in absence of magnetic field ,
thermopower increases and thermal conductivity decreases with increase of the hybridization energy . in presence of magnetic field perpendicular to the ultra - thin topological insulator , thermoelectric coefficients exhibit quantum oscillations with inverse magnetic field , whose frequency is strongly modified by the zeeman energy and phase factor is governed by the product of the lande @xmath0-factor and the hybridization energy .
in addition to the numerical results , the low - temperature approximate analytical results of the thermoelectric coefficients are also provided .
it is also observed that for a given magnetic field these transport coefficients oscillate with hybridization energy , whose frequency depends on the lande @xmath0-factor . .
And you have already written the first three sentences of the full article: recently a new class of material , called topological insulator , has been paid much attention by condensed matter physicists @xcite .
topological insulator ( ti ) shows the conduction of electrons on the surface of 3d materials otherwise behaves as an insulator .
it is due to the time - reversal symmetry possessed by materials like bi@xmath1se@xmath2 , sb@xmath3te@xmath4 and bi@xmath3te@xmath4@xcite ..
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the conducting surface states of these material show a single dirac cone , in which spin is always locked perpendicular to it s momentum .
the angle resolved photoemission spectroscopy @xcite or scanning tunneling microscopy @xcite has been used to realize the single dirac cone in tis . in two - dimensional electron systems , under the presence of a perpendicular magnetic field , electron conducts along the boundary due to the circular orbits bouncing off the edges , leading to skipping orbits .
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Suppose that you have an abstract for a scientific paper: we report the discovery of a very bright ( m@xmath0 ) lyman break galaxy at @xmath1 that appears to be a massive system in a late stage of merging .
deep imaging reveals multiple peaks in the brightness profile with angular separations of @xmath2@xmath3 ( @xmath225 @xmath4 kpc comoving ) .
in addition , high signal - to - noise ratio rest - frame uv spectroscopy shows evidence for @xmath5 components based on stellar photospheric and ism absorption lines with a velocity dispersion of @xmath6 km s@xmath7 for the three strongest components .
both the dynamics and high luminosity , as well as our analysis of a @xmath8cdm numerical simulation , suggest a very massive system with halo mass @xmath9 .
the simulation finds that all halos at @xmath10 of this mass contain sub - halos in agreement with the properties of these observed components and that such systems typically evolve into @xmath11 halos in groups and clusters by @xmath12 .
this discovery provides a rare opportunity to study the properties and individual components of @xmath13 systems that are likely to be the progenitors to brightest cluster galaxies . .
And you have already written the first three sentences of the full article: massive galaxies and galaxy clusters at high redshift provide strong constraints on cosmological models and galaxy formation scenarios . the lyman break galaxies ( lbgs ) are a widespread population of high redshift galaxies selected by their rest - frame fuv colors @xcite .
lbgs at @xmath14 tend to reside in massive halos @xmath15 @xcite and are therefore believed to evolve into present - day massive elliptical galaxies .
although @xmath16 color - selected @xmath17 lbgs have spectroscopic confirmations ( e.g. * ? ? ?.
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* ; * ? ? ?
* ; * ? ? ?
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Suppose that you have an abstract for a scientific paper: total and differential cross sections for @xmath0 and @xmath1 photoproduction off the proton have been determined with the cbelsa / taps detector for photon energies between 0.85 and 2.55 gev .
the @xmath0 mesons are detected in their two neutral decay modes , @xmath2 and @xmath3 , and for the first time , cover the full angular range in @xmath4 of the @xmath0 meson .
these new @xmath0 photoproduction data are consistent with the earlier cb - elsa results .
the @xmath1 mesons are observed in their neutral decay to @xmath5 and also extend the coverage in angular range . .
And you have already written the first three sentences of the full article: understanding the structure of the proton and its excited states is one of the key questions in hadronic physics . known as the missing - baryon problem ,
quark models based on three constituent quark degrees of freedom predict many more states than have been observed experimentally .
baryon resonances are broad and widely overlap , especially at higher energies , imposing challenges on the interpretation of experimental data in terms of resonance contributions . without precise data from many decay channels , it will be difficult or even impossible to accurately determine the properties of well established resonances , or to confirm or rule out the existence of weakly established resonances or new , so - far not observed states . of particular importance.
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are well - chosen decay channels which can help isolate contributions from individual excited states and clarify their importance .
photoproduction of @xmath0 and @xmath1 mesons offers the distinct advantage of serving as an _ isospin filter _ for the spectrum of nucleon resonances and thus , simplifies data interpretations and theoretical efforts to predict the excited states contributing to these reactions .
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Suppose that you have an abstract for a scientific paper: we report the discovery with xmm - newton of correlated spectral and timing behavior in the ultraluminous x - ray source ( ulx ) ngc 5408 x-1 .
an @xmath0 ksec pointing with xmm / newton obtained in january , 2008 reveals a strong 10 mhz qpo in the @xmath1 kev flux , as well as flat - topped , band limited noise breaking to a power law .
the energy spectrum is again dominated by two components , a @xmath2 kev thermal disk and a power - law with an index of @xmath3 .
these new measurements , combined with results from our previous january 2006 pointing in which we first detected qpos , show for the first time in a ulx a pattern of spectral and temporal correlations strongly analogous to that seen in galactic black hole sources , but at much higher x - ray luminosity and longer characteristic time - scales .
we find that the qpo frequency is proportional to the inferred disk flux , while the qpo and broad - band noise amplitude ( root mean squared , rms ) are inversely proportional to the disk flux .
assuming that qpo frequency scales inversely with black hole mass at a given power - law spectral index we derive mass estimates using the observed qpo frequency - spectral index relations from five stellar - mass black hole systems with dynamical mass constraints .
the results from all sources are consistent with a mass range for ngc 5408 x-1 from 1000 - 9000 @xmath4 .
we argue that these are conservative limits , and a more likely range is from 2000 - 5000 @xmath4 . moreover , the recent relation from gierlinski et al .
that relates black hole mass to the strength of variability at high frequencies ( above the break in the power spectrum ) is also indicative of such a high mass for ngc 5408 x-1 .
importantly , none of the above estimates appears consistent with a black hole mass less than @xmath5 @xmath4 for ngc 5408 x-1 .
we argue that these new findings strongly support the conclusion that ngc 5408 x-1 harbors an intermediate mass black hole . .
And you have already written the first three sentences of the full article: the nature of the bright x - ray sources found in nearby galaxies , the ultraluminous x - ray sources ( ulxs ) , remains a major astrophysical puzzle .
the fundamental conundrum is that some of these objects have x - ray luminosities uncomfortably high to be stellar - mass black holes ( bh ) without violating standard eddington limit arguments .
three different solutions have been proposed for the luminosity problem ..
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1 ) the objects are intermediate - mass bhs ( colbert & mushotzky 1999 ) .
2 ) they are stellar - mass bhs with , in some cases , substantial beaming of their x - ray radiation ( king et al .
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Suppose that you have an abstract for a scientific paper: we investigate the electronic and magnetic properties of ( ga , mn)n nanocrystals using the density functional theory . we study both wurtzite and zinc - blende structures doped with one or two substitutional mn impurities . for a single mn dopant placed close to surface ,
the behavior of the empty mn - induced state , hereafter referred to as `` mn hole '' , is different from bulk ( ga , mn)n . the energy level corresponding to this off - center mn hole lies within the quantum dot gap near the conduction edge . for two mn dopants , the most stable magnetic configuration is antiferromagnetic , and this result was unexpected since ( ga , mn)n bulk shows ferromagnetism in the ground state .
the surprising antiferromagnetic alignment of two mn spins is ascribed also to the holes linked to the mn impurities that approach the surface . unlike ( ga , mn)n bulk
, these mn holes in confined ( ga , mn)n nanostructures do not contribute to the ferromagnetic alignment of the two mn spins . .
And you have already written the first three sentences of the full article: wide band - gap nitride semiconductors are currently used in full - color displays , white light sources , and ultraviolet laser diodes for high - density storage systems.@xcite such semiconductors combine group - v nitrogen with elements of group iii such as boron , aluminium , gallium , and indium .
recently , the well - known nitride compound gan has been extensively investigated in the form of quantum dots , both with wurtzite@xcite and zinc - blende@xcite crystal structures .
the typical phenomena appearing in quantum dots are the discretization of the electronic spectra and the blue shift of the fundamental gaps.@xcite moreover , the gan nanocrystals can be doped with diluted magnetic impurities such as manganese ..
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in fact , ref .
12 shows ( ga , mn)n quantum dots prepared under solvothermal conditions in the wurtzite phase . these particles seem to show a ferromagnetic signal in the ground state,@xcite like bulk ( ga , mn)n as calculated for diluted mn spins.@xcite we must note that many experiments on bulk ( ga , mn)n suggest that mn spins are not diluted but forming clusters which give the observed ferromagnetism.@xcite a comparative _ ab - initio _ study between ( ga , mn)n nanocrystals in wurtzite and zinc - blende phases is nevertheless missing . in this work
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Suppose that you have an abstract for a scientific paper: while single - layer graphene shows extraordinary phenomena which are stable against electronic interactions , the non - interacting state of bilayer graphene is unstable to infinitesimal interactions leading to one of many possible exotic states .
indeed a gapped state is found in experiments but none of the states proposed so far can provide full accounts of its properties . here
we show that a _ magnetoelectric _ ( me ) state is consistent with the experimental observations .
this state breaks time - reversal symmetry through a pair of spontaneously generated current loops in each layer , and has odd - parity with respect to the two layers .
we also suggest further experiments to check whether the me state is indeed the gapped state found in experiments . .
And you have already written the first three sentences of the full article: the non - interacting electronic state in bilayer graphene with ab ( bernal ) stacking , whose lattice structure is illustrated in fig . 1 , has a pair of degenerate valence and conduction bands at two momentum points @xmath0 in the brillouin zone .
the energy varies quadratically with the momentum about these points , in contrast with the linear dispersion in the single - layer graphene .
@xcite with hopping energy @xmath1 between the stacking carbon atoms in different layers , the other two pairs of conduction and valence bands have energy at @xmath2 at the degeneracy points ..
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such a state with chemical potential at the charge neutrality point is unstable to infinitesimal electron - electron interactions . in weak - coupling approximation ,
in which the interaction energies are small compared to @xmath1 , one may look for instabilities restricting the hamiltonian to the set of lowest energy conduction and valence bands .
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Suppose that you have an abstract for a scientific paper: we investigate the large order aspects of the @xmath0-expansion under the estimation procession of the critical quantities . as illustrative examples ,
we revisit the one - dimensional ising model for the analytic study and the two - dimensional square ising model in the high - temperature phase for the numerical experiment to large orders . in both models ,
the proposed fundamental base on which the estimation protocol should be constructed is investigated in details and confirmed to be valid . in the square lattice model
, we present a new protocol for the estimation of critical exponents and temperature . .
And you have already written the first three sentences of the full article: over an year ago , we studied an ising model on a cubic lattice @xcite by use of the @xmath0 expansion @xcite .
the study is based upon the high temperature expansion and the resulting series rewritten in the inverse of a mass squared @xmath1 is transformed by the @xmath0-expansion which played a crucial role in the estimation of critical quantities . however the foundamentals of the estimation protocol , which will be explicitly stated in the next section , have not been thoroughly investigated so far .
this paper deals with the issue in enough depth via the study of ising models at one- and two - dimensions where the models are solved and high temperature expansion is available to very large orders ..
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another purpose of this paper is to improve the estimation protocol of critical quantities employed in ref .
we will give a renewed procedure and confirm it works better in the low dimensional models , where the estimation of @xmath2 , @xmath3 and @xmath4 will be presented on the square lattice . the new protocol
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10,271 |
Suppose that you have an abstract for a scientific paper: kernel - based methods in numerical analysis have the advantage of yielding optimal recovery processes in the native hilbert space @xmath0 in which they are reproducing . continuous kernels on compact domains have an expansion into eigenfunctions that are both @xmath1-orthonormal and orthogonal in @xmath0 ( mercer expansion ) .
this paper examines the corresponding eigenspaces and proves that they have optimality properties among all other subspaces of @xmath0 .
these results have strong connections to @xmath2-widths in approximation theory , and they establish that errors of optimal approximations are closely related to the decay of the eigenvalues .
though the eigenspaces and eigenvalues are not readily available , they can be well approximated using the standard @xmath2-dimensional subspaces spanned by translates of the kernel with respect to @xmath2 nodes or centers .
we give error bounds for the numerical approximation of the eigensystem via such subspaces .
a series of examples shows that our numerical technique via a greedy point selection strategy allows to calculate the eigensystems with good accuracy . * _ keywords : _ * mercer kernels , radial basis functions , eigenfunctions , eigenvalues , @xmath2-widths , optimal subspaces , greedy methods + * _ 2000 msc : _ * 41axx , 41a46 , 41a58 , 42cxx , 42c15 , 42a82 , 45p05 , 46e22 , 47a70 , 65d05 , 65f15 , 65r10 , 65t99 .
And you have already written the first three sentences of the full article: we start with a few background facts about kernel - based methods .
details can be retrieved from the monographs @xcite and the surveys @xcite .
let @xmath3 be a nonempty set , and let @xmath4 be a positive definite and symmetric kernel on @xmath5 ..
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associated with @xmath6 there is a unique _ native space _
@xmath7 , that is a separable hilbert space of functions @xmath8 where k is the reproducing kernel .
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Suppose that you have an abstract for a scientific paper: in this study , one - dimensional systems of masses connected by springs , i.e. , spring - chain systems , are investigated numerically .
the average kinetic energy of chain - end particles of these systems is larger than that of other particles , which is similar to the behavior observed for systems made of masses connected by rigid links .
the energetic motion of the end particles is , however , transient , and the system relaxes to thermal equilibrium after a while , where the average kinetic energy of each particle is the same , that is , equipartition of energy is achieved .
this is in contrast to the case of systems made of masses connected by rigid links , where the energetic motion of the end particles is observed in equilibrium .
the timescale of relaxation estimated by simulation increases rapidly with increasing spring constant .
the timescale is also estimated using the boltzmann - jeans theory and is found to be in quite good agreement with that obtained by the simulation . .
And you have already written the first three sentences of the full article: constrained systems are those having constraints on their degrees of freedom .
when a constraint is imposed on spatial coordinates , the constraint is called a `` holonomic constraint''@xcite .
constrained systems are useful and simple , because of which they are widely used as model systems ..
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an example of such a model system is a freely jointed chain @xcite , which is a model composed of one - dimensional chain ( 1d ) of @xmath0 masses such that the distances between adjacent masses are constant .
the freely jointed chain is known as a simplified model of polymers . in computational software packages such as charmm
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Suppose that you have an abstract for a scientific paper: in the framework of the euronu design study , a new design for the cern to frjus neutrino beam based on the spl is under development by the wp2 group .
the main challenge of this project lies with the design of a multi - mw neutrino beam facility .
the horn and the decay tunnel parameters have been optimized to maximize any potential discovery .
the target design , thermo - mechanical analysis , and power supply design of the horn system as well as any safety issues are being studied to meet the mw power requirements for the proton - beam . _
( contribution to nufact 11 , xiiith international workshop on neutrino factories , super beams and beta beams , 1 - 6 august 2011 , cern and university of geneva ( submitted to iop conference series ) ) _ .
And you have already written the first three sentences of the full article: the summary of the recent target and horn studies for the cern to frjus neutrino beam is presented in this paper .
the main design and the physics reach of the super beam project are described in @xcite .
the optimization procedure for the horn shape and layout - geometry to achieve optimum physics , the study of a target able to withstand a multi - mw proton - beam power , multi - physics simulation to investigate heat transfer , cooling and mechanical stress for the horn and safety aspects are discussed here ..
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a 4-mw proton - beam from cern s spl is foreseen to be separated by a series of kicker magnets into four beam lines .
then each beam will be focused by a series of quadruples and correctors to a four horn / target assembly ( figure [ fig : 4horn ] ) . in this way , each horn / target assembly is able to accommodate better the multi - mw power and thus increasing its lifetime @xcite .
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Suppose that you have an abstract for a scientific paper: the impressive progress of the kinetic schemes in the solution of gas dynamics problems and the development of effective parallel algorithms for modern high performance parallel computing systems led to the development of advanced methods for the solution of the magnetohydrodynamics problem in the important area of plasma physics .
the novel feature of the method is the formulation of the complex boltzmann - like distribution function of kinetic method with the implementation of electromagnetic interaction terms .
the numerical method is based on the explicit schemes . due to logical simplicity and its efficiency ,
the algorithm is easily adapted to modern high performance parallel computer systems including hybrid computing systems with graphic processors .
magnetohydrodynamics ( mhd ) , kinetic scheme , high performance computing .
And you have already written the first three sentences of the full article: the tremendous progress in the development of high performance computing systems , especially expecting drastically new exascale computing systems , including the challenges in architecture , scale , power and reliability , gives new opportunities for the mathematical modeling of important physical phenomena in the present and future .
nevertheless the complexity of the challenges in science and engineering continues to outpace our ability to adequately address them through impressively growing computational power .
a feature of the present is that the development of technologies and computer systems architecture are well ahead of software development ..
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the software problems are primarily associated with the complexity of the algorithms adaptation for the differential equations of mathematical physics to high performance computing systems architecture .
in particular they refer to one of the important requirements as the accuracy in combination with the correctness of the initial mathematical models .
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Suppose that you have an abstract for a scientific paper: transverse one dimensional foliations play an important role in the study of codimension one foliations . in @xcite ,
the authors introduced the notion of flow box decomposition of a 3-manifold @xmath0 .
this is a combinatorial decomposition of @xmath0 that reflects both the structure of a given codimension one foliation and that of a given transverse flow , and that is amenable to inductive strategies . in this paper , flow box decompositions
are used to extend some classical foliation results to foliations that are not @xmath1 .
enhancements of well - known results of calegari on smoothing leaves , dippolito on denjoy blowup of leaves , and tischler on approximations by fibrations are obtained .
the methods developed are not intrinsically 3-dimensional techniques , and should generalize to prove corresponding results for codimension one foliations in @xmath2-dimensional manifolds . .
And you have already written the first three sentences of the full article: smoothness plays an important role in the theory of codimension one foliations of 3-manifolds .
reeb constructed the first @xmath3 foliation on @xmath4 as the union of two foliated solid tori , or reeb components @xcite .
this work of reeb , together with work of alexander @xcite and wallace @xcite , led to the proofs by lickorish @xcite and novikov and zieschang @xcite that any closed 3-manifold has a @xmath3 codimension one foliation . on the other hand.
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, haefliger @xcite showed that no foliation of @xmath4 can be analytic .
this was greatly improved by novikov @xcite to show that any @xmath1 foliation of @xmath4 must have reeb components , and these never exist in analytic foliations .
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Suppose that you have an abstract for a scientific paper: it is shown how to sew string vertices with ghosts at tree level in order to produce new tree vertices using the group theoretic approach to string theory .
it is then verified the brst invariance of the sewn vertex and shown that it has the correct ghost number .
pacs number : 11.25 0.5 cm .
And you have already written the first three sentences of the full article: in the early days of string theory , one way to obtain amplitudes for the scattering of an arbitrary number of strings was by using the factorization property , what means that the scattering amplitude of @xmath0 strings may be interpreted as the scattering amplitudes of a smaller number of strings sewn together .
this made it possible to build the @xmath0 string scattering amplitude by knowing the expression for three string scattering amplitudes .
even though they were very ingenious and successful , those calculations did nt take into account the ghost structure of the vertices , and that is what is done here . in @xcite.
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, it was shown how to sew tree vertices without ghosts using the group theoretic approach to string theory @xcite in order to obtain a new , composite vertex .
following the same procedure , we shall calculate the scattering amplitude of @xmath0 strings taking account the ghost structure .
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Suppose that you have an abstract for a scientific paper: for the first time , we report a large - scale wave that was observed simultaneously in the photosphere , chromosphere , transition region and low corona layers of the solar atmosphere . using the high temporal and high spatial resolution observations taken by the solar magnetic activity research telescope at hida observatory and the atmospheric imaging assembly ( aia ) onboard _ solar dynamic observatory _ , we find that the wave evolved synchronously at different heights of the solar atmosphere , and it propagated at a speed of 605 km s@xmath0 and showed a significant deceleration ( -424 m s@xmath1 ) in the extreme - ultraviolet ( euv ) observations . during the initial stage ,
the wave speed in the euv observations was 1000 km s@xmath0 , similar to those measured from the aia 1700 ( 967 km s@xmath0 ) and 1600 ( 893 km s@xmath0 ) observations .
the wave was reflected by a remote region with open fields , and a slower wave - like feature at a speed of 220 km s@xmath0 was also identified following the primary fast wave .
in addition , a type - ii radio burst was observed to be associated with the wave .
we conclude that this wave should be a fast magnetosonic shock wave , which was firstly driven by the associated coronal mass ejection and then propagated freely in the corona . as the shock wave propagated , its legs swept the solar surface and thereby resulted in the wave signatures observed in the lower layers of the solar atmosphere .
the slower wave - like structure following the primary wave was probably caused by the reconfiguration of the low coronal magnetic fields , as predicted in the field - line stretching model . .
And you have already written the first three sentences of the full article: large - scale wave - like perturbations in the solar atmosphere have been observed for many years .
for example , the h@xmath2 moreton wave @xcite , the 10830 wave @xcite , the extreme - ultraviolet ( euv ) wave @xcite and the soft x - ray ( sxr ) wave @xcite . the h@xmath2 moreton wave , which manifests as a propagating dark / white front in the h@xmath2 off - band dopplergrams , has been recognized as a chromospheric surface wave observed immediately following an impulsive flare @xcite .
observations have indicated that the 10830 and sxr waves are consistent with the chromospheric moreton wave and thereby they were interpreted as fast - mode waves and were thought to be the counterparts of the moreton wave at different heights @xcite . for the euv waves ,.
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significant controversy remains over their physical natures and origins .
so far , there are several competing interpretations for the euv waves , including the fast - mode wave model @xcite , the slow - mode wave model @xcite , and the non - wave models which are related to a current shell or successive restructuring of field lines caused by coronal mass ejections ( cmes ) @xcite . in addition
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Suppose that you have an abstract for a scientific paper: this is the first paper of a series aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features .
simultaneous h@xmath0 , na i d@xmath1 , d@xmath2 , and he i d@xmath3 spectroscopic observations are reported here for 18 systems . the chromospheric contribution in these lines
have been determined using the spectral subtraction technique .
very broad wings have been found in the subtracted h@xmath0 profile of some of the more active stars .
these profiles are well matched using a two - components gaussian fit ( narrow and broad ) and the broad component could be interpreted as arising from microflaring .
prominence - like extended material have been detected in a near - eclipse h@xmath0 observation of the system ar lac .
the excess emission found in the na i d@xmath1 and d@xmath2 lines by application of the spectral subtraction technique and the behaviour of the h@xmath0 line in the corresponding simultaneous observations indicate that the filling - in of the core of these lines is a chromospheric activity indicator . for giant stars of the sample the he i
d@xmath3 line has been detected in absorption in the subtracted spectra .
an optical flare has been detected in ux ari and ii peg through the presence of the he i d@xmath3 in emission in coincidence with the enhancement of the h@xmath0 emission . .
And you have already written the first three sentences of the full article: the chromospherically active binaries are detached binary systems with cool components characterized by strong chromospheric , transition region , and coronal activity .
the rs cvn systems have at least one cool evolved component whereas both components of the by dra binaries are main sequence stars ( fekel et al .
1986 ) . in this series of papers we try to study the chromosphere of this kind of extremely active stars using the information provided by several optical spectroscopic features that could be used as chromospheric activity indicators ..
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the simultaneous observations of different lines , that are formed at different height in the chromosphere ( from the region of temperature minimum to the higher chromosphere ) , are of special interest for stellar activity studies since they provide very useful information about this stellar region .
ideally , simultaneous observations should be performed at all wavelengths in order to develop a coherent 3-d atmosphere model . in practice ,
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Suppose that you have an abstract for a scientific paper: in this paper , we give an algorithm to compute the hat version of heegaard floer homology of a closed oriented three - manifold .
this method also allows us to compute the filtration coming from a null - homologous link in a three - manifold . .
And you have already written the first three sentences of the full article: heegaard floer homology is a collection of invariants for closed oriented three - manifolds , introduced by peter ozsvth and zoltn szab @xcite .
there are four versions , denoted by @xmath0 and @xmath1 , which are graded abelian groups . the hat version @xmath2 is defined as the homology of a chain complex @xmath3 coming from a heegaard diagram of the three - manifold @xmath4 .
the differentials count the number of points in certain moduli spaces of holomorphic disks , which are hard to compute in general ..
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there is also a relative version of the theory corresponding to pairs @xmath5 , where @xmath6 is a knot in @xmath4 .
if @xmath6 is null - homologous , then a seifert surface @xmath7 of @xmath6 induces a filtration of the chain complex @xmath3 , and the chain homotopy type of the filtered chain complex is a knot invariant .
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Suppose that you have an abstract for a scientific paper: in this paper we propose a kronecker - based modeling of large networks with unknown interconnection links .
the class of kronecker networks is defined for which we formulate a vector autoregressive model .
its coefficient - matrices are decomposed into a sum of kronecker products . when the network is labeled such that the number of terms in the sum is small compared to the size of the matrix , exploiting this kronecker structure leads to high data compression .
two algorithms were designed for an efficient estimation of the coefficient - matrices , namely a non - iterative and overparametrized algorithm as well as an alternating least squares minimization .
we prove that the latter always converges to the true parameters for non - zero initial conditions .
this framework moreover allows for a convenient integration of more structure ( e.g sparse , banded , toeplitz ) on smaller - size matrices .
numerical examples on atmospheric turbulence data has shown comparable performances with the unstructured least - squares estimation while the number of parameters is growing _ only linearly _ w.r.t . the number of nodes instead of quadratically in the full unstructured matrix case .
network modeling , large - scale systems , kronecker product , low - rank approximation , multi - convex minimization . .
And you have already written the first three sentences of the full article: modeling large - scale networks has been stirring much developments in various fields such as machine learning and system identification .
the assembly of numerous systems interacting with one another arises in fields such as biology , e.g with the brain neurons in @xcite , optics with the atmospheric turbulence , and many others . due to the large size of input - output data batches , identifying locally
the behavior of the network is a major challenge that has been mainly addressed by using prior knowledge on how the subsystems , or nodes , are connected to one another ..
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one common assumption is sparsity and relies on the fact that each node is connected to a limited number of other nodes with respect to the network s size .
other well - studied structures include interconnected one - dimensional strings of subsystems in @xcite , or clusters of different subsystems with known connection patterns , named as alpha - heterogeneous in @xcite .
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Suppose that you have an abstract for a scientific paper: this paper studies a wireless powered communication network ( wpcn ) consisting of a hybrid access point ( h - ap ) and multiple user equipments ( ues ) , all of which operate in full - duplex ( fd ) .
we first propose a transceiver structure that enables fd operation of ues to receive energy in the downlink ( dl ) and transmit information in the uplink ( ul ) simultaneously .
we then provide an energy usage model in the proposed ue transceiver accounting for energy leakage from transmit chain to receive chain .
it is shown that throughput of fd wpcn with the proposed fd ues can be maximized by optimally allocating ul transmission time to ues by solving a convex optimization problem .
simulation results reveal that the use of the proposed fd ues efficiently improves the throughput of wpcn with practical self - interference cancellation capability at the h - ap .
[ section ] [ section ] [ section ] [ section ] [ section ] [ section ] [ section ] .
And you have already written the first three sentences of the full article: as a new way to power mobile devices , there has been a growing interest in harvesting energy from the far - field radio - frequency ( rf ) signal transmissions . in particular , design of wireless - powered communication network ( wpcn ) has been studied as a significant application of rf energy harvesting , where remote user equipments ( ues ) utilize the energy harvested from wireless rf transfer of power for wireless communications .
one typical wpcn model has been proposed in @xcite , in which wireless energy transfer ( wet ) in the downlink ( dl ) and wireless information transmissions ( wit ) in the uplink ( ul ) are both coordinated by a hybrid access - point ( h - ap ) . in wpcns where the h - ap and ues all operate in half duplex ( hd ) , termed as hd - wpcns , a fundamental trade - off exists in allocations of resources to dl for wet and ul for wit @xcite , because allocating more resources to dl for wet increases transmit power of ues in the ul thanks to the increase in the amount of harvested energy , but also decreases resources allocated to ul for wit .
meanwhile , full duplex ( fd ) based wireless systems have a great deal of attention , in which the wireless nodes transmit and receive rf signals at the same time and in the same frequency band ..
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fd operation is expected to potentially double the spectral efficiency in wireless communications by cancelling the leakage of transmitted signal received by itself , i.e. , self - interference ( si ) . in particular , feasibility of the fd communication
has been verified by proof - of - concept ( poc ) , by showing that the power of residual si after self - interference cancellation ( sic ) is reduced close enough to the power of background noise @xcite , @xcite .
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Suppose that you have an abstract for a scientific paper: performing a fit to all publicly available data , we analyze the extent to which the latest results from the lhc and tevatron constrain the couplings of the higgs boson - like state at @xmath0 . to this end
we assume that only standard model ( sm ) particles appear in the higgs decays , but tree - level higgs couplings to the up - quarks , down - quarks and vector bosons , relative to the sm are free parameters .
we also assume that the leptonic couplings relative to the sm are the same as for the down - quark , and a custodial symmetry for the @xmath1 couplings . in the simplest approach ,
the effective higgs couplings to gluons and photons are computed in terms of the previous parameters .
this approach is also applied to two - higgs - doublet models of type i and type ii .
however , we also explore the possibility that the net higgs to @xmath2 and @xmath3 couplings have extra loop contributions coming from beyond - the - standard model physics .
we find that the sm @xmath4-value @xmath5 is more than @xmath6 away from fits in which : a ) there is some non - sm contribution to the @xmath3 coupling of the higgs ; or b ) the sign of the top quark coupling to the higgs is opposite that of the w coupling . in both these cases @xmath4-values @xmath7 can be achieved . since option b ) is difficult to realize in realistic models , it would seem that new physics contributions to the effective couplings of the higgs are preferred .
lapth-061/12 + lpsc12350 + lpt orsay 12 - 119 + nsf - kitp-12 - 236 g. blanger@xmath8 , b. dumont@xmath9 , u. ellwanger@xmath10 , j. f. gunion@xmath11 , s. kraml@xmath9 .
And you have already written the first three sentences of the full article: the recent discovery @xcite of a new particle with properties consistent with a standard model ( sm ) higgs boson is clearly the most significant news from the large hadron collider ( lhc ) .
this discovery was supported by evidence for a higgs boson found by the cdf and d0 collaborations at the tevatron @xcite and completes our picture of the sm .
however , the sm leaves many fundamental questions open perhaps the most pressing issue being that the sm does not explain the value of the electroweak scale , the higgs mass , itself . clearly , a prime goal after the discovery is to thoroughly test the sm nature for this higgs - like signal ..
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the sm makes precise predictions for the production cross sections of the higgs boson @xmath12 ( via gluon - gluon fusion ( ggf ) , vector boson fusion ( vbf ) , associated production with an electroweak gauge boson @xmath1 ( vh ) and associated production with a @xmath13 pair ( ) ) , and its decay branching fractions into various final states ( @xmath14 , @xmath15 , @xmath16 , @xmath17 , and @xmath18 ) as a function of its unpredicted mass @xmath19 .
the observation of the higgs boson at the lhc is based primarily on the @xmath20 @xcite , @xmath15 @xcite and @xmath16 @xcite decay modes .
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Suppose that you have an abstract for a scientific paper: several ten @xmath0 m gan have been deposited on a silicon substrate using a two - step hydride vapor phase epitaxy ( hvpe ) process .
the substrates have been covered by aln layers and gan nanostructures grown by plasma - assisted molecular - beam epitaxy . during the first low - temperature ( low-@xmath1 )
hvpe step , stacking faults ( sf ) form , which show distinct luminescence lines and stripe - like features in cathodoluminescence images of the cross - section of the layers .
these cathodoluminescence features allow for an insight into the growth process . during a second high - temperature ( high-@xmath1 ) step ,
the sfs disappear , and the luminescence of this part of the gan layer is dominated by the donor - bound exciton . for templates consisting of both a thin aln buffer and gan nanostructures , a silicon incorporation into the gan grown by hvpe is not observed .
moreover , the growth mode of the ( high-@xmath1 ) hvpe step depends on the specific structure of the aln / gan template , where in a first case , the epitaxy is dominated by the formation of slowly growing facets , while in a second case , the epitaxy proceeds directly along the @xmath2-axis . for templates without gan nanostructures , cathodoluminescence spectra excited close to the si / gan interface
show a broadening toward higher energies indicating a silicon incorporation on a high dopant level . .
And you have already written the first three sentences of the full article: in order to improve , e. g. , the performance of nitride - based laser diodes , the density of threading dislocations penetrating into the corresponding layer systems need to be further reduced .
this is a difficult task , when growing such device structures on foreign substrates , e. g. , on sapphire , silicon carbide , or silicon due to a strain - related generation of extended defects .
therefore , the interest in the fabrication of bulk gan substrates as well as of free - standing gan layers ( fs - gan ) for a subsequent homo - epitaxial deposition of device structures is growing ..
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hydride vapor phase epitaxy ( hvpe ) has already proven to be well suited for the fabrication of fs - gan with threading dislocation densities below 10@xmath3 @xmath4 .
@xcite commonly , sapphire wafers are used as substrates for the hvpe process to grow fs - gan .
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Suppose that you have an abstract for a scientific paper: we present a high - resolution 5-ghz radio continuum map of the starburst galaxy ngc 2146 made with merlin and the vla ( a - array ) , in a search of radio supernovae and supernova remnants expected to be already produced by the most massive stars in the starburst . at 5 ghz ,
about 20 point sources were detected earlier by glendenning @xmath0 kronberg ( 1986 ) in the central 800 pc of ngc 2146 .
our observations with higher sensitivity and resolution made with merlin and the vla confirms the detection of 18 sources , and resolves 7 of them .
additional 1.6-ghz merlin observations disclose 9 sources coincident in position with those detected at 5 ghz , which allows us to derive their spectral indices @xmath1 , ( @xmath2 ) .
only 3 sources have indices ( @xmath3 @xmath4 0 ) consistent with synchrotron emission from supernova remnants or radio supernovae , while the others have very steep inverted spectra ( @xmath3 @xmath5 0 ) .
+ we suggest that the sources with positive spectral index are optically thick ultra
compact and/or ultra dense hii regions with high electron densities and high emission measures ( em @xmath5 @xmath6 @xmath7 pc ) .
minimum energy requirements indicate that these regions may contain up to 1000 equivalent stars of type o6 , comparable to the number of stars found in super starclusters .
when compared with m82 , the galaxy ngc 2146 lacks however a large number of supernova remnants .
we suggest that ngc 2146 is experiencing a burst of star formation stronger than that in m82 , but being in a younger phase . in this phase , only few stars have already exploded , whereas the others cause strong thermal emission from compact , optically thick ionized gas regions , around the young super starclusters .
+ we may , however , not exclude an alternative scenario in which strong free - free absorption at 1.6 ghz in foreground ionized gas with very high emission measures ( em @xmath5 @xmath8 @xmath7 pc ) hides a certain number of supernova remnants , thus rendering for some....
And you have already written the first three sentences of the full article: ngc 2146 is a starburst galaxy located at a distance of 14.5 mpc ( 1@xmath9 70 pc ) .
its infrared luminosity measured with iras at 60 @xmath10 and 100 @xmath10 is @xmath11 @xmath12 .
this value and the large 25 @xmath10 to 60 @xmath10 flux ratio place the object in the lower part of the ir luminosity / spectral index plane populated by superluminous galaxies without active nuclei ( hutchings et al ..
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ngc 2146 has a central molecular ring ( jackson & ho @xcite , young et al .
@xcite ) , and an outflow of hot gas along the minor axis driven by supernova explosions and stellar winds in the starburst region ( armus et al .
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Suppose that you have an abstract for a scientific paper: we report the results of a submillimeter array ( sma ) interferometric observation of 21-@xmath0 m source iras 07134 + 1005 in the co @xmath12 line . in order to determine the morpho - kinematic properties of the molecular envelope of the object
, we constructed a model using the _ shape _ software to model the observed co map .
we find that the molecular gas component of the envelopes can be interpreted as a geometrically thick expanding torus with an expanding velocity of 8 km s@xmath2 .
the inner and outer radii of the torus determined by fitting _ shape _
models are 1.2@xmath3 and 3.0@xmath3 , respectively .
the inner radius is consistent with the previous values determined by radiative transfer modeling of the spectral energy distribution and mid - infrared imaging of the dust component .
the radii and expansion velocity of the torus suggest that the central star has left the asymptotic giant branch about 11401710 years ago , and that the duration of the equatorial enhanced mass loss is about 25603130 years . from the absence of an observed jet
, we suggest that the formation of a bipolar outflow may lack behind in time from the creation of the equatorial torus . .
And you have already written the first three sentences of the full article: the unidentified 21 @xmath0 m feature was first discovered in carbon - rich proto - planetary nebulae ( ppn , * ? ? ?
* ) and 16 21-@xmath0 m sources have been found to date @xcite .
although 20 years have past and a variety of chemical materials have been suggested as a possible carrier , no firm identification has been made ..
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previously proposed candidates include hydrogenated amorphous carbon @xcite , hydrogenated fullerences @xcite , nanodiamonds @xcite , tic nanoclusters @xcite and o - substituted five - member carbon rings @xcite , sic @xcite , etc . since the observation of the 21-@xmath0 m feature
is confined to the ppn phase of stellar evolution , one may ask whether the formation or excitation of the feature is related to the dynamical evolution of post - agb evolution . for example , one may conclude that the physical conditions ( temperature and density ) governing the chemical reactions may be related to the morphology and kinematics of the envelope .
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Suppose that you have an abstract for a scientific paper: in this paper , we will analyse a theory of modified gravity , in which the field content of general relativity will be increased to include a vector field .
we will use the horndeski formalism to non - minimally couple this vector field to the metric . as we will be using the horndeski formalism
, this theory will not contain ostrogradsky ghost degree of freedom .
we will analyse compact stars using this vector - tensor - horndeski theory . .
And you have already written the first three sentences of the full article: even though general relativity is a very well - tested theory , there is a strong motivation to modify general relativity at large scale . this is because to explain the accelerating cosmic expansion in general relativity , a cosmological constant has to be included @xcite .
even though the existence of such a cosmological constant is predicted from quantum field theories , quantum field theories predict a cosmological constant which is @xmath0 times larger than the observed value of the cosmological constant .
this has motivated the study of modified theories of gravity , and the scalar - tensor theories are such a modification of general relativity which could explain accelerating cosmic expansion @xcite ..
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however , these theories in general contain higher derivative terms in the action , and such higher derivative terms gives rise to ostrogradsky ghost degree of freedom .
these in turn cause instabilities in the theory called the ostrogradsky instabilities .
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Suppose that you have an abstract for a scientific paper: we present an extended grid of mean three - dimensional ( 3d ) spectra for low - mass , pure - hydrogen atmosphere da white dwarfs ( wds ) .
we use co5bold radiation - hydrodynamics 3d simulations covering @xmath0 = 600011,500 k and @xmath1 = 56.5 ( @xmath2 in cm s@xmath3 ) to derive analytical functions to convert spectroscopically determined 1d temperatures and surface gravities to 3d atmospheric parameters . along with the previously published 3d models ,
the 1d to 3d corrections are now available for essentially all known convective da wds ( i.e. , @xmath1 = 59 ) . for low - mass wds , the correction in temperature is relatively small ( a few per cent at the most ) , but the surface gravities measured from the 3d models are lower by as much as 0.35 dex .
we revisit the spectroscopic analysis of the extremely low - mass ( elm ) wds , and demonstrate that the 3d models largely resolve the discrepancies seen in the radius and mass measurements for relatively cool elm wds in eclipsing double wd and wd + milli - second pulsar binary systems .
we also use the 3d corrections to revise the boundaries of the zz ceti instability strip , including the recently found elm pulsators . .
And you have already written the first three sentences of the full article: recent three dimensional ( 3d ) radiation hydrodynamical simulations of the sun and main - sequence stars have led to significant improvements in our knowledge of stellar atmospheres and spectroscopic abundance measurements ( e.g. * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
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* ; * ? ? ?
the major differences between the 1d and 3d model atmospheres result from the insufficient description of convection by the mixing length theory ( * ? ? ?
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Suppose that you have an abstract for a scientific paper: the long range potential of helium - helium interaction , which requires accurate _ ab initio _ calculation , due to the small value of the potential depth , approximately 11 k ( @xmath0 ev = 0.091 kj / mol ) at 2.96 , will be obtained in this study by an alternative technique .
this work presents a robust and consistent procedure that provides the long range potential directly from experimental data .
however , it is difficult to obtain experimental data containing information regarding such a small potential depth .
thereby , sensitivity analysis will be used to circumvent this difficulty , from which viscosity data at lower temperatures ( @xmath1 k ) were chosen as appropriate data to be used to retrieve the potential function between 3 and 4 . the linear relationship between the potential energy function and the viscosity coefficient
will be established under quantum assumptions and the bose - einstein statistic .
the use of quantum theory is essential , since the temperatures are below 5 k. the potential obtained in this study describes the viscosity with an average error of 1.68 % that is less than the experimental error ( 5 % ) , with the results being similar to those obtained for recent _ ab initio _ potentials .
* keywords : * variable phase method . viscosity coefficient . low temperature . sensitivity analysis . .
And you have already written the first three sentences of the full article: potential energy functions play a central role in chemistry , and from these functions , the properties of a system can , in principle , be determined . often , the potential energy function is obtained from _ ab initio _ methods , but it can also be determined from experimental data using inverse techniques .
inverse problems theory to handle experimental data has been applied to refine potential energy functions from the second virial coefficient,@xcite differential cross - sections@xcite and phase shifts.@xcite the helium diatomic system at low temperatures has received considerable attention in recent years due to quantum and relativistic effects in their thermodynamics and transport properties.@xcite the theoretical interpretation of the results has been performed with the _ ab initio _
potential function.@xcite the helium dimer has a very small potential well depth , measuring approximately 11 k,@xcite consequently , highly accurate calculations are required to obtain the potential energy function.@xcite the present paper presents an alternative way to refine the helium potential energy function from viscosity coefficient data at low temperatures ..
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few studies have been conducted along this line and often at high temperatures,@xcite limit in which classical theory is valid , and in parametric form , usually for a lennard - jones potential energy curve.@xcite to gain insight into this problem , an investigation into the sensitivity@xcite of the viscosity coefficient to the potential energy function is conducted , and an adequate temperature range for experimental data was observed .
the present study shows a higher sensitivity for long range potential in the temperature range below 5 k. since it is necessary to use viscosity coefficient data at low temperatures in an inverse procedure , a quantum strategy to refine the potential energy curve is necessary and will be presented in this study .
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Suppose that you have an abstract for a scientific paper: we report on the observation of photogalvanic effects induced by terahertz radiation in type - ii gasb / inas quantum wells with inverted band order .
photocurrents are excited at oblique incidence of radiation and consists of several contributions varying differently with the change of the radiation polarization state ; the one driven by the helicity and the other one driven by the linearly polarization of radiation are of comparable magnitudes .
experimental and theoretical analyses reveal that the photocurrent is dominated by the circular and linear photogalvanic effects in a system with a dominant structure inversion asymmetry .
a microscopic theory developed in the framework of the boltzmann equation of motion considers both photogalvanic effects and describes well all the experimental findings . .
And you have already written the first three sentences of the full article: in recent years , type - ii gasb / inas two dimensional ( 2d ) structures have attracted growing attention in both theoretical and applied research .
a distinguish feature of the gasb / inas quantum well ( qw ) structures and superlattices is that electrons and holes are mostly localized in the inas and gasb layers , respectively , and that the energy gap between the electron and hole subbands can be efficiently tuned by adjusting the widths of the layers , for reviews see e.g @xcite .
narrow gap type - ii gasb / inas superlattices , being characterized by a small effective mass , high mobility , excellent electron confinement , and the possibility of modulation doping , became an important system for mid - infrared radiation detection @xcite and were proposed as a novel candidate for terahertz ( thz ) radiation detectors @xcite ..
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furthermore , it has been shown most recently that type - ii gasb / inas qws can be tuned through the topological quantum phase transition by the variation of the layer thicknesses and/or the application of front- and back - gate voltage @xcite .
this property should enable the fabrication of high - quality materials with an interchanged band order , a crucial issue for nontrivial 2d topological insulators ( tis ) @xcite .
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Suppose that you have an abstract for a scientific paper: density functional theory and density functional tight - binding are applied to model electron transport in copper nanowires of approximately 1 nm and 3 nm diameters with varying crystal orientation and surface termination .
the copper nanowires studied are found to be metallic irrespective of diameter , crystal orientation and/or surface termination .
electron transmission is highly dependent on crystal orientation and surface termination .
nanowires oriented along the [ 110 ] crystallographic axis consistently exhibit the highest electron transmission while surface oxidized nanowires show significantly reduced electron transmission compared to unterminated nanowires .
transmission per unit area is calculated in each case , for a given crystal orientation we find that this value decreases with diameter for unterminated nanowires but is largely unaffected by diameter in surface oxidized nanowires for the size regime considered .
transmission pathway plots show that transmission is larger at the surface of unterminated nanowires than inside the nanowire and that transmission at the nanowire surface is significantly reduced by surface oxidation
. finally , we present a simple model which explains the transport per unit area dependence on diameter based on transmission pathways results . .
And you have already written the first three sentences of the full article: due to continued nanoelectronics scaling , metal interconnects as well as transistors in integrated circuits are becoming ever smaller and are approaching atomic scale dimensions @xcite . as a consequence , understanding the effects of size - dependent phenomena on material properties is becoming ever more critical to enable efficient device performance .
present day transistor technologies use copper as an interconnect material , however it is unknown if at the small cross - sections required for future technologies copper will be able to fulfill this function effectively due to increased resistances ; measured line resistivity increases dramatically for cu nanowires ( nws ) compared to bulk materials .
@xcite it is required that the electrical conductivity of small cross section copper nanostructures be understood to maintain acceptable power consumption in future nanoelectronics generations ..
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in particular the contribution of the individual scattering sources , such as surfaces,@xcite grain boundaries,@xcite electron - phonon interaction @xcite and impurities , to overall resistivity needs to be assessed to aid development of interconnects which minimize line resistance .
a succinct overview of these issues can be found in the review of josell , brongersma and tkei.@xcite in general the dominant scattering mechanism in metal nanostructures is dependent on processing conditions and the geometry of the resulting nanostructures .
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Suppose that you have an abstract for a scientific paper: we report the detection of variable linear polarization from sgr a * at a wavelength of @xmath0 mm , the longest wavelength yet at which a detection has been made .
the mean polarization is @xmath1% at a position angle of @xmath2 with rms scatters of 0.4% and 9@xmath3 over the five epochs .
we also detect polarization variability on a timescale of days .
combined with previous detections over the range 150400ghz ( 7502000@xmath4 m ) , the average polarization position angles are all found to be consistent with a rotation measure of @xmath5radm@xmath6 .
this implies that the faraday rotation occurs external to the polarized source at all wavelengths .
this implies an accretion rate @xmath7yr@xmath8 for the accretion density profiles expected of adaf , jet and cdaf models and assuming that the region at which electrons in the accretion flow become relativistic is within @xmath9 .
the inferred accretion rate is inconsistent with adaf / bondi accretion .
the stability of the mean polarization position angle between disparate polarization observations over the frequency range limits fluctuations in the accretion rate to less than @xmath10% .
the flat frequency dependence of the inter - day polarization position angle variations also makes them difficult to attribute to rotation measure fluctuations , and suggests that both the magnitude and position angle variations are intrinsic to the emission . .
And you have already written the first three sentences of the full article: linear polarization can be an important diagnostic of relativistic jets and accretion flows associated with black hole systems . in the case of the massive black hole in the galactic center , sgr a * , the properties of its mm - wavelength linear polarization probes the accretion environment on scales inaccessible with other techniques ( bower et al.1999a , b ; aitken et al.2001 ; bower et al.2001 ; bower et al.2003 ; marrone et al.2006 ) . the apparent absence of linear polarization at wavelengths exceeding 2.7 mm and sharp rise in polarization fraction at shorter wavelengths sets an upper limit to the rotation measure ( rm ) .
this limits the mass accretion rate to @xmath11 at distances of @xmath12 schwarzschild radii from the black hole , which eliminates certain classes of accretion flow ( quataert & gruzinov 2000 ; agol 2000 ) , but is consistent with cdaf and jet models ( e.g. falcke , mannheim and biermann 1993 ) .
the rm measures the accretion rate by serving as a proxy for the electron column density once coupled with assumptions about the magnetic field ..
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equipartition between kinetic , magnetic and gravitational energy is often assumed to relate the electron density and magnetic field ( e.g. bower et al .
1999a ; melia & falcke 2001 ; marrone et al .
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Suppose that you have an abstract for a scientific paper: in this paper , we study gravitational - wave ( gw ) emission from a hypothetical supermassive black - hole ( smbh ) binary at the center of m87 .
the existence of a smbh other than that usually identified with the central agn is a possible explanation for the observed displacement ( @xmath0 ) between the agn and the galactic centroid , and it is reasonable to assume considering the evolution of smbhs through galaxy mergers . because the period of the binary and the resulting gws is much longer than the observational time span
, we calculate the variation of the gw amplitude , rather than the amplitude itself .
we investigate the dependence on the orbital elements and the second bh mass taking the observational constraints into account .
the frequency of the gws is too low to be detected with the conventional pulsar timing array and we propose a new method to detect such low - frequency gws with the distribution function of pulsar spin - down rates .
although the gws from a smbh binary which explains the observed displacement is extremely hard to be detected even with the new method , gws are still a useful way to probe the m87 center . .
And you have already written the first three sentences of the full article: a giant elliptical galaxy m87 ( ngc 4486 ) , located at 18.4 mpc , hosts one of the nearest and best - studied agn .
a relativistic one - sided jet is ejected from the galactic center , where a supermassive black hole ( smbh ) with a mass of @xmath1 @xcite resides , and extends to hundreds of kilo parsecs .
it was reported in @xcite that the luminous center of m87 and the agn are displaced significantly ..
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the displacement was confirmed in @xcite and this fact suggests that the smbh is not located at the center of mass of the galaxy , although there is a large uncertainty in the projected distance ( @xmath2 ) .
several scenarios have been suggested to interpret this displacement : ( 1 ) accelaration by an asymmetric jet , ( 2 ) recoil due to gravitational - wave emission caused by a merger of two smbhs , ( 3 ) binary motion with respect to another smbh and ( 4 ) gravitational perturbations from multiple massive objects at the galactic center . as a possible method to distinguish between these scenarios , observation of the proper motion of the smbh ( agn ) was suggested .
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Suppose that you have an abstract for a scientific paper: we report on the first experimental setup based on a 2d-/3d - mot scheme to create both bose - einstein condensates and degenerate fermi gases of several ytterbium isotopes .
our setup does not require a zeeman slower and offers the flexibility to simultaneously produce ultracold samples of other atomic species .
furthermore , the extraordinary optical access favors future experiments in optical lattices .
a 2d - mot on the strong @xmath0 transition captures ytterbium directly from a dispenser of atoms and loads a 3d - mot on the narrow @xmath1 intercombination transition .
subsequently , atoms are transferred to a crossed optical dipole trap and cooled evaporatively to quantum degeneracy . .
And you have already written the first three sentences of the full article: owing to their unique properties , alkaline - earth - like atoms have become the subject of intense experimental and theoretical research in recent years .
ultracold gases of these two - electron atoms have been proposed for the realization and study of a variety of novel quantum systems including heavy fermion materials and the kondo insulator@xcite , su(n)-symmetric hamiltonians@xcite , quantum information processing@xcite and artificial gauge fields@xcite .
quantum degenerate gases have been reported by only a few groups for isotopes of ytterbium@xcite ( yb ) , strontium@xcite , and calcium@xcite ..
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however , all of these experiments rely on zeeman slowers as the initial cooling stage . from the early days of laser cooling@xcite
it is well known that zeeman@xcite or chirp@xcite slowing of a thermal beam enhances the loading rate of a magneto - optical trap ( mot ) by many orders of magnitude as compared to loading from a background vapor directly .
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Suppose that you have an abstract for a scientific paper: we present progress towards a new measurement of the electron electric dipole moment using a cold supersonic beam of ybf molecules .
data are currently being taken with a sensitivity of @xmath0 .
we therefore expect to make an improvement over the tl experiment of commins group , which currently gives the most precise result .
we discuss the systematic and statistical errors and comment on the future prospect of making a measurement at the level of @xmath1 .
address = centre for cold matter , imperial college london , london , sw7 2bw , uk + e - mail : [email protected] .
And you have already written the first three sentences of the full article: the most precise electric dipole moment ( edm ) measurement @xcite on the electron gives @xmath2 , a result consistent with zero .
a non - zero result at this level would necessarily mean the violation of time reversal symmetry ( t ) symmetry and the existence of new particle physics , beyond the standard model @xcite .
although the standard model does exhibit t violation through the ckm mechanism , the electron edm produced by this mechanism is roughly ten orders of magnitude below the present experimental sensitivity and is for all practical purposes zero ..
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by contrast , many modern extensions of particle theory lead quite naturally to a value in the current range of @xmath3 or a little below @xcite . since our experiment using cold ybf molecules aims to be more sensitive than this ,
it is a search for new physics . assuming the validity of cpt
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Suppose that you have an abstract for a scientific paper: new results on the production of @xmath0 and @xmath1 hyperons in pb+pb interactions at 40 @xmath2gev and @xmath3 at 30 @xmath2gev are presented .
transverse mass spectra as well as rapidity spectra of these hyperons are shown and compared to previously measured data at different beam energies .
the energy dependence of hyperon production ( 4@xmath4 yields ) is discussed .
additionally , the centrality dependence of @xmath5 production at 40 @xmath2gev is presented . .
And you have already written the first three sentences of the full article: measurements of strange particles provide information on the properties of strongly interacting matter at early stages of heavy ion collisions . on the assumption that a deconfinement phase transition occurs in heavy ion collisions
, we have to look for qualitative changes ( onset phenomena ) when varying external parameters like system size and energy density .
therefore , we study @xmath3 , @xmath0 and @xmath1 production as a function of beam energy and @xmath5 production dependent on the collision centrality ..
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this contribution reports on the first results of the @xmath3 production at 30 @xmath2gev and @xmath0 and @xmath1 production at 40 @xmath2gev .
the na49 experiment @xcite is a large acceptance hadron spectrometer which consists of four tpcs .
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Suppose that you have an abstract for a scientific paper: classical acoustoelasticity couples small - amplitude elastic wave propagation to an infinitesimal pre - deformation , in order to reveal and evaluate non - destructively third - order elasticity constants . here
, we see that acoustoelasticity can be also be used to determine fourth - order constants , simply by coupling a small - amplitude wave with a small - but - finite pre - deformation .
we present results for compressible weakly nonlinear elasticity , we make a link with the historical results of bridgman on the physics of high pressures , and we show how to determine @xmath0 " , the so - called fourth - order elasticity constant of soft ( incompressible , isotropic ) solids by using infinitesimal waves . _
keywords : _ acousto - elasticity , high pressures , large pre - tension , elastic constants .
And you have already written the first three sentences of the full article: acoustoelasticity is now a well established experimental technique used for the non - destructive measurement of third - order elasticity ( toe ) constants of solids , and its principles can be found in standard handbooks of physical acoustics , such as @xcite . the underlying theory , however , is quite intricate , and over the years several authors have produced different and irreconcilable expressions for the shift experienced by the wave speed when elastic wave propagation is coupled to a pre - strain .
a common mistake found in the literature consists of the implicit assumption that since a small pre - strain and a small - amplitude wave are described by linearized equations , they can be superposed linearly . with that point of view , the coupling between the two phenomena is of higher order and can be neglected in the first approximation .
the flaw in that reasoning is simply that these phenomena are _ successive _ , not linearly superposed ..
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experiencing an infinitesimal pre - strain from a stress - free configuration is a linear process ; propagating an infinitesimal wave in a stress - free configuration is another linear process .
but in acoustoelasticity , the wave travels in a pre - stressed , not a stress - free solid , and the laws of linear elastodynamics must be adapted to reflect this fact .
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Suppose that you have an abstract for a scientific paper: we have strong evidence on all cosmic scales , from galaxies to the largest structures ever observed , that there is more matter in the universe than we can see .
galaxies and clusters would fly apart unless they would be held together by material which we call dark , because it does not shine in photons .
although the amount of dark matter and its distribution are fairly well established , we are clueless regarding its composition .
leading candidates are weakly interacting massive particles ( wimps ) , which are cold thermal relics of the big bang , ie moving non - relativistically at the time of structure formation .
these particles can be detected via their interaction with nuclei in deep - underground , low - background detectors .
experiments dedicated to observe wimp interactions for the first time reach sensitivities allowing to probe the parameter space predicted by supersymmetric theories of particle physics .
current results of high sensitivity direct detection experiments are discussed and the most promising projects of the future are presented . if a stable new particle exists at the weak scale , it seems likely to expect a discovery within this decade . .
And you have already written the first three sentences of the full article: more than seventy years after zwicky s first accounts of dark matter in galaxy clusters @xcite , and thirty five years after rubin s measurements of rotational velocities of spirals @xcite , the case for non - baryonic dark matter remains convincing .
recent precision observations of the cosmic microwave background @xcite and of large scale structures @xcite confirm the picture in which more than 90% of the matter in the universe is revealed only by its gravitational interaction .
the nature of this matter is not known . a class of generic candidates are weakly interacting massive particles ( wimps ) which could have been thermally produced in the very early universe ..
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it is well known that if the mass and cross section of these particles is determined by the weak scale , the freeze - out relic density is around the observed value , @xmath0 0.1 .
the prototype wimp candidate is the neutralino , or the lightest supersymmetric particle , which is stable in supersymmetric models where r - parity is conserved .
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Suppose that you have an abstract for a scientific paper: in this paper we present an analytical study on the synchronization dynamics observed in unidirectionally - coupled quasiperiodically - forced systems that exhibit _ strange non - chaotic attractors ( sna ) _ in their dynamics .
the sna dynamics observed in the uncoupled system is studied analytically through phase portraits and poincare maps .
a difference system is obtained by coupling the state equations of similar piecewise linear regions of the drive and response systems .
the mechanism of synchronization of the coupled system is realized through the bifurcation of the eigenvalues in one of the piecewise linear regions of the difference system .
the analytical solutions obtained for the normalized state equations in each piecewise linear region of the difference system has been used to explain the synchronization dynamics though phase portraits and timeseries analysis .
the stability of the synchronized state is confirmed through the _ master stability function_. an explicit analytical solution explaining the synchronization of snas is reported in the literature for the first time . .
And you have already written the first three sentences of the full article: strange non - chaotic attractors ( snas ) are geometrical structures existing between periodic and chaotic attractors .
snas have been insensitive to initial conditions as evidenced by the negative values of their lyapunov exponents . however , they have the complicated geometrical structure of fractals .
snas are generic in quasiperiodically forced systems . after pioneering work of grebogi @xcite , a large number of quasiperiodic systems were reported for the existence of sna behavior ..
Please generate the next two sentences of the article
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different routes , such as the heagy - hammel or torus doubling , fractalization , intermittency , blow out bifurcation routes , to sna have been identified @xcite .
a good number of nonlinear systems and electronic circuits exhibiting snas in their dynamics have been studied numerically and experimentally @xcite while a few systems have been studied analytically @xcite .
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Suppose that you have an abstract for a scientific paper: a parameter - free statistical model is used to study multiplicity signatures for coherent production of charged - pairs of parabosons of order @xmath0 in comparison with those arising in the case of ordinary bosons , @xmath1 .
two non - negative real parameters arise because @xmath2 " and @xmath3 " are fundamentally distinct pair operators of charge ` @xmath4 ' , a - quanta and charge ` @xmath5 ' , b - quanta parabosons . in 3d plots of @xmath6@xmath7 the probability of @xmath8 paraboson charged - pairs + @xmath9 positive parabosons " versus @xmath10 and @xmath11 , the @xmath1 curve is found to lie on the relatively narrow 2d @xmath0 surface
. = -5 mm * coherent production of pairs of parabosons of order 2 * + nicholas frascino and charles a. nelson + _ department of physics , state university of new york at binghamton + binghamton , n.y .
13902 _ .
And you have already written the first three sentences of the full article: this paper is a theoretical study of multiplicity signatures in coherent production of charged - pairs of parabosons [ 1 - 3 ] of order @xmath0 in comparison with those arising in the case of ordinary bosons , @xmath1 .
the investigation is partially motivated by phenomenological coherence analyses , circa 1970 , of inelastic @xmath12 pair production from fixed targets with laboratory kinetic - energies up to 27 gev by c.p . wang [ 4 ] , and by horn and silver[5 ] .
the present analysis is possible because the conserved - charge boson coherent states of [ 5 , 6 ] are analogous to ones recently constructed for order @xmath0 parabosons [ 7 ] ..
Please generate the next two sentences of the article
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one physical consequence of order @xmath0 " is that two or less such bosons can occupy a totally anti - symmetric state . appendix 1 contains a brief review of @xmath0 paraboson statistics .
both the @xmath0 and @xmath1 models considered in this paper are notably `` statistical '' and crudely `` unrealistic '' in being free of kinematic and dynamical parameters associated with physically important production quantities such as the distributions of available energy / momentum , the kinematic size and other characteristics of the production region , resonances , masses and other conserved quantum numbers ( e.g. isotopic spin in the @xmath1 case [ 8 ] ) , because only the @xmath13-charge conservation constraint has been imposed . consequently , unlike what some readers would expect the situation to be from consideration of other particle - production models , in the figures the relative sizes of different aspects of the peaks , and of other structures , of the surfaces / curves can not be adjusted without additional assumptions and complications .
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