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8,700 | Suppose that you have an abstract for a scientific paper: we have obtained high - resolution , high s / n near - uv - blue spectra of 22 very metal - poor stars ( [ fe / h ] @xmath0 ) with subaru / hds , and measured the abundances of elements from c to th . the metallicity range of the observed stars is @xmath1 [ fe / h ] @xmath2 .
as found by previous studies , the star - to - star scatter in the measured abundances of neutron - capture elements in these stars is very large , much greater than could be assigned to observational errors , and in comparison with the relatively small scatter in the @xmath3- and iron - peak elements . in spite of the large scatter in the ratios of the neutron - capture elements relative to iron , the abundance _
patterns _ of heavy neutron - capture elements ( @xmath4 ) are quite similar within our sample stars . the ba / eu ratios in the 11 very metal - poor stars in our sample in which both elements have been detected are nearly equal to that of the solar system r - process component .
moreover , the abundance patterns of the heavy neutron - capture elements ( 56 @xmath5 70 ) in seven objects with clear enhancements of the neutron - capture elements are similar to that of the solar system r - process component .
these results prove that heavy neutron - capture elements in these objects are primarily synthesized by the r - process .
in contrast , the abundance ratios of the light neutron - capture elements ( 38 @xmath6 _ z _ @xmath6 46 ) relative to the heavier ones ( 56 @xmath6 _ z _ @xmath6 70 ) exhibit a large dispersion .
our inspection of the correlation between sr and ba abundances in very metal - poor stars reveals that the dispersion of the sr abundances clearly decreases with increasing ba abundance .
this trend is naturally explained by hypothesizing the existence of two processes , one that produces sr without ba , and another that produces sr and ba in similar proportions .
this result should provide a strong constraint on the origin of the light neutron - capture elements at low metallicity .
we....
And you have already written the first three sentences of the full article: the very metal - poor stars , presently found in the halo of the galaxy , are believed to have formed at the earliest times , shortly after it became possible for the universe to make stars with sufficiently long main - sequence lifetimes ( i.e. , masses @xmath11 ) to survive for @xmath12 gyr .
the chemical compositions of these stars are thus expected to reflect a quite small number of nucleosynthesis processes , possibly as small as one , while the compositions of more metal - rich stars like the sun reflect the cumulative ( hence quite complex ) results of the various processes that have been in operation during the entire history of galactic chemical evolution .
recent abundance analyses for extremely metal - poor stars have provided quite valuable information on the individual nucleosynthesis processes involved ( e.g. , * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ; * ? ? ? |
8,701 | Suppose that you have an abstract for a scientific paper: results on diffraction from the fermilab tevatron collider obtained by the cdf ii collaboration using data from @xmath0 collisions at @xmath11.96 tev are reviewed and compared with theoretical expectations .
implications for predictions of exclusive higgs boson production rates at the large hadron collider are discussed .
address = the rockefeller university , 1230 york avenue , new york , ny 10065 , usa .
And you have already written the first three sentences of the full article: vs. @xmath2 topologies for sd@xmath3single diffraction , dd@xmath3double diffraction , dpe@xmath3double pomeron exchange , sdd@xmath3sd@xmath4dpe , and exclusive final state production . the hatched areas in the @xmath5-@xmath2 plots represent regions where particle production occurs.,scaledwidth=70.0% ] the phenomenal success of the standard model is tainted by our inability to analytically calculate `` soft '' processes , where the strong coupling constant is large and perturbative techniques fail . yet
, a fundamental understanding of soft processes may help reveal the underlying mechanism of confinement and explain the intricacies of hadron structure .
experimentally , diffractive processes may be used as tools for new discoveries , as they provide low background environments for certain production channels , among which most notable is the exclusive production of higgs bosons ( see sec ..
Please generate the next two sentences of the article | [ sec : dijets ] ) .
the cdf collaboration has reported several results on soft and hard diffraction processes from @xmath6 collisions at the fermilab tevatron using rapidity gaps and / or a leading antiproton as a signature for diffraction ( fig . [ |
8,702 | Suppose that you have an abstract for a scientific paper: in the framework of semihard ( k@xmath0 factorization ) qcd approach , we consider the differential cross sections of @xmath1 meson production at hera . the consideration is based on bfkl and ccfm gluon distributions .
we find that in the case of bfkl lo gluon distribution the theoretical results are sensitive to the pomeron intercept parameter @xmath2 .
we present a comparison of the theoretical results with available zeus experimental data . .
And you have already written the first three sentences of the full article: the experimental results on deep inelastic charm production obtained by the h1 @xcite and zeus @xcite collaborations at hera provide a strong impetus for further theoretical studies .
this process is truly semihard because of the presence of two larges scales : the virtuality of the exchanged photon ( @xmath3 ) and the charm mass ( @xmath4 ) , both being much larger than @xmath5 but much smaller than @xmath6 .
therefore , in the present note , we focus on the semihard approach @xcite ( sha ) , which we had applied earlier to the @xmath1 meson photoproduction @xcite in a similar manner ..
Please generate the next two sentences of the article | it is known that the resummation @xcite of the terms @xmath7^n,\;$ ] @xmath8^n\;$ ] and @xmath9^n$ ] in sha results in the so called unintegrated gluon distribution + @xmath10 , which determines the probability to find a gluon carrying the longitudinal momentum fraction @xmath11 and transverse momentum @xmath12 at the probing scale @xmath13 .
it obeys the bfkl equation @xcite and reduces to the conventional gluon density @xmath14 once the @xmath15 dependence is integrated out : @xmath16 the factorization scale @xmath13 ( such that @xmath17 @xmath18 ) indicates the scale of the nonperturbative input distribution . |
8,703 | Suppose that you have an abstract for a scientific paper: we study opportunistic interference management when there is bursty interference in parallel @xmath0-user linear deterministic interference channels .
a degraded message set communication problem is formulated to exploit the burstiness of interference in @xmath1 subcarriers allocated to each user .
we focus on symmetric rate requirements based on the number of interfered subcarriers rather than the exact set of interfered subcarriers .
inner bounds are obtained using erasure coding , signal - scale alignment and han - kobayashi coding strategy .
tight outer bounds for a variety of regimes are obtained using the el gamal - costa injective interference channel bounds and a sliding window subset entropy inequality @xcite .
the result demonstrates an application of techniques from multilevel diversity coding to interference channels .
we also conjecture outer bounds indicating the sub - optimality of erasure coding across subcarriers in certain regimes . .
And you have already written the first three sentences of the full article: in multicarrier systems like ofdm , subcarriers allocated to a user may face interference due to a variety of reasons .
these include the activity of other users and allocation decisions of neighbouring base stations in a cellular network .
predicting the presence or absence of interference in a particular subcarrier may not be feasible at a transmitter in such uncoordinated networks ..
Please generate the next two sentences of the article | nevertheless , it is practical to assume that a subcarrier allocated to a user does not face interference in every channel instantiation .
thus , there is a scope for harnessing such _ bursty _ |
8,704 | Suppose that you have an abstract for a scientific paper: we present a study by linear stability analysis and large - scale monte carlo simulations of a simple model of biological coevolution .
selection is provided through a reproduction probability that contains quenched , random interspecies interactions , while genetic variation is provided through a low mutation rate . both selection and mutation act on individual organisms .
consistent with some current theories of macroevolutionary dynamics , the model displays intermittent , statistically self - similar behavior with punctuated equilibria . the probability density for the lifetimes of ecological communities
is well approximated by a power law with exponent near @xmath0 , and the corresponding power spectral densities show @xmath1 noise ( flicker noise ) over several decades .
the long - lived communities ( quasi - steady states ) consist of a relatively small number of mutualistically interacting species , and they are surrounded by a `` protection zone '' of closely related genotypes that have a very low probability of invading the resident community . the extent of the protection zone affects the stability of the community in a way analogous to the height of the free - energy barrier surrounding a metastable state in a physical system .
measures of biological diversity are on average stationary with no discernible trends , even over our very long simulation runs of approximately @xmath2 generations . .
And you have already written the first three sentences of the full article: biological evolution offers a number of important , unsolved problems that are well suited for investigation by methods from statistical physics .
many of these can be studied using complex , interacting model systems far from equilibrium @xcite .
areas that have generated exceptional interest among physicists are those of coevolution and speciation ..
Please generate the next two sentences of the article | a large class of coevolution models have been inspired by one introduced by bak and sneppen @xcite , in which species with different levels of fitness " compete , and the least fit species and those that interact with it are regularly mutated " and replaced by new species with different , randomly chosen fitness .
models in this class exhibit avalanches of extinctions and appear to evolve towards a self - organized critical state @xcite . |
8,705 | Suppose that you have an abstract for a scientific paper: we calculate the magnetization torque due to the spin polarization of the itinerant electrons by deriving the kinetic spin bloch equations based on the @xmath0-@xmath1 model .
we find that the first - order gradient of the magnetization inhomogeneity gives rise to the current - induced torques , which are consistent to the previous works . at the second - order gradient
, we find an effective magnetic field perpendicular to the spin stiffness filed .
this field is proportional to the nonadiabatic parameter @xmath2 .
we show that this vertical spin stiffness term can significantly modify the domain - wall structure in ferromagnetic semiconductors and hence should be included in the landau - lifshitz - gilbert equation in studying the magnetization dynamics . .
And you have already written the first three sentences of the full article: ferromagnetic systems have attracted much interest for a long history because of the intriguing physics and applications.@xcite as the development of information technology , the research on magnetization dynamics in micromagnets has become an active field.@xcite great efforts have been devoted to this field by aiming to manipulate magnetization more efficiently.@xcite for theoretical simulation , the magnetization dynamics is usually described by the landau - lifshitz - gilbert ( llg ) equation,@xcite @xmath3 where @xmath4 represents the direction of the magnetization . @xmath5 in the first term on the right - hand side of eq.([eq1 ] ) is the effective magnetic field which drives the magnetization procession and determines the domain structure in the equilibrium states . up to date
, different sources of effective magnetic field have been identified , e.g. , the external magnetic field , the crystal anisotropy induced by the spin - orbit coupling , the exchange energy due to the spatial inhomogeneity , and also the demagnetization field from dipole - dipole interaction.@xcite the second term , the gilbert damping torque , describes the magnetization relaxation to the effective field axis on the time scale of @xmath6.@xcite the last one with first - order gradient of the magnetization is the spin torque induced by the transport of the spin polarized itinerant electrons , where @xmath7 is proportional to the spin current density.@xcite the @xmath2-term,@xcite first proposed by zhang and li,@xcite was demonstrated to be critically important to the current - driven domain wall motion , which overwhelms the threshold current due to pinning force and transverse anisotropy for domain wall motion@xcite and results in the steady domain wall velocity @xmath8 in the absence of the external magnetic field .
therefore , the determination of the effective magnetic field and the parameters in the llg equation , such as @xmath9 and @xmath2 , is an important issue for magnetization dynamics study.@xcite previously , we....
Please generate the next two sentences of the article | from the first - order gradient of the magnetization inhomogeneity , we obtain the current - induced torques which are consistent to the above llg equation . within the second - order gradient
, we find that the llg equation should be modified and written as @xmath10 the second - order gradient introduces two contributions to the effective magnetic field . the one given by @xmath11 |
8,706 | Suppose that you have an abstract for a scientific paper: we extend the investigation of the gravitational collapse of a spherically symmetric yang - mills field in einstein gravity and show that , within the black hole regime , a new kind of critical behavior arises which separates black holes formed via type i collapse from black holes formed through type ii collapse .
further , we provide evidence that these new attracting critical solutions are in fact the previously discovered colored black holes with a single unstable mode .
i#1 # 1 epsf .
And you have already written the first three sentences of the full article: it is by now relatively well known that gravitational collapse can produce rich structure even within highly simplified systems such as spherical symmetry . in particular , near the threshold of black hole formation , the strong field dynamics of general relativity exhibits critical phenomena . the pioneering work demonstrating this critical behavior in the collapse of a single massless
scalar field @xcite has been supplemented by investigations of gravitational waves @xcite , a perfect fluid @xcite and a variety of other matter models , all of which exhibit the same general characteristics .
indeed , to our knowledge no system which has been studied in this context has been shown _ not _ to exhibit this critical phenomena . at this point in the subject s development ,.
Please generate the next two sentences of the article | dynamical evolutions ( solutions of the full partial differential equations of motion ) , in tandem with analytic and perturbative calculations have given us a reasonable understanding of many of the phenomenological details of critical behavior in collapse .
( see @xcite for an excellent review of the subject . ) in light of this , one of the more interesting discoveries in some of the more recently studied models @xcite is the presence of two distinct types of behavior at the threshold of black hole formation . |
8,707 | Suppose that you have an abstract for a scientific paper: in this paper we address the problem of a particle moving in singular one dimensional potentials in the framework of quantum mechanics with minimal length . using the momentum space representation
we solve exactly the schrodinger equation for the dirac delta potential and coulomb potential .
the effect of the minimal length is revealed by a computation of effective generalized dirac delta potential and coulomb potential .
pacs numbers : 02.40.gh,03.65.ge .
And you have already written the first three sentences of the full article: in a serie of papers kempf et al .
@xcite introduced a deformed quantum mecahnics based on generalized uncertainty principle ( gup ) .
other similar issues leading to the same gup have been also initiated by some authors @xcite ..
Please generate the next two sentences of the article | one major consequence of the gup is the appearance of minimal uncertainties in position and/or momentum leading to an uv / ir mixing , which allows to probe short distance physics ( uv ) from long distance one ( ir ) .
a minimal uncertainty in position or minimal length has appeared in different context like string theory ven , groos , amati , loop quantum gravity @xcite and non - commutative field theories @xcite . |
8,708 | Suppose that you have an abstract for a scientific paper: over the last few years , the sloan digital sky survey ( sdss ) has discovered several hundred quasars with redshift between 4.0 and 6.4 . including the effects of magnification bias , one expects a priori that an appreciable fraction of these objects are gravitationally lensed .
we have used the advanced camera for surveys on the _ hubble space telescope _ to carry out a snapshot imaging survey of high - redshift sdss quasars to search for gravitationally split lenses .
this paper , the first in a series reporting the results of the survey , describes snapshot observations of four quasars at @xmath0 and 6.30 , respectively .
we find that none of these objects has a lensed companion within 5 magnitudes with a separation larger than @xmath1 arcseconds ; within 2.5 magnitudes , we can rule out companions within 0.1 arcseconds .
based on the non - detection of strong lensing in these four systems , we constrain the @xmath2 luminosity function to a slope of @xmath3 @xmath4 , assuming a break in the quasar luminosity function at @xmath5 .
we discuss the implications of this constraint on the ionizing background due to quasars in the early universe . given that these quasars are not highly magnified , estimates of the masses of their central engines by the eddington argument must be taken seriously , possibly challenging models of black hole formation . .
And you have already written the first three sentences of the full article: before 1995 , only 24 quasars with redshifts larger than four had been published ; most had been found in multicolor or grism surveys for high - redshift quasars ( e.g. , warren et al .
1987 ; schmidt , schneider , & gunn 1987 ) . in the past eight years
the number of known @xmath6 quasars has increased to more than 400 , largely due to the discoveries from the sloan digital sky survey ( sdss ; 2000 ) and the digitized palomar sky survey ( kennefick , djorgovski , & meylan 1996 ) ..
Please generate the next two sentences of the article | the sdss to date has published the discovery of over 200 quasars with redshifts greater than 3.6 ( fan et al .
2001b ; anderson et al . 2001 |
8,709 | Suppose that you have an abstract for a scientific paper: we study the prediction of solar flare size and time - to - flare using 38 features describing magnetic complexity of the photospheric magnetic field . this work uses support vector regression to formulate a mapping from the 38-dimensional feature space to a continuous - valued label vector representing flare size or time - to - flare . when we consider flaring regions only , we find an average error in estimating flare size of approximately half a _ geostationary operational environmental satellite _ ( _ goes _ ) class .
when we additionally consider non - flaring regions , we find an increased average error of approximately 3/4 a _ goes _ class .
we also consider thresholding the regressed flare size for the experiment containing both flaring and non - flaring regions and find a true positive rate of 0.69 and a true negative rate of 0.86 for flare prediction .
the results for both of these size regression experiments are consistent across a wide range of predictive time windows , indicating that the magnetic complexity features may be persistent in appearance long before flare activity .
this is supported by our larger error rates of some 40 hr in the time - to - flare regression problem .
the 38 magnetic complexity features considered here appear to have discriminative potential for flare size , but their persistence in time makes them less discriminative for the time - to - flare problem . .
And you have already written the first three sentences of the full article: solar flares are powerful events resulting from the sudden conversion of stored magnetic energy to particle acceleration and excess radiation in the corona , and releasing up to @xmath0 total erg of energy @xcite .
solar flares can have significant detrimental effects on earth , including disruption and damage to satellites , power grids , and telecommunications infrastructure @xcite .
since coronal magnetic field measurements are not currently available , much research has focused on the inference of coronal magnetic field structure from the photospheric magnetic field . in this , it is assumed that turbulent motions in the photosphere create complex photospheric magnetic configurations @xcite , and this will then be reflected in complex coronal magnetic configurations @xcite ..
Please generate the next two sentences of the article | complex coronal field configurations store the energy that is released as a solar flare .
several researchers have studied the use of poisson statistics to relate flare rate of different active region ( ar ) classes ( e.g. , mcintosh or mount wilson classes ) to probability of observing a c- , m- , or x - class flare @xcite . |
8,710 | Suppose that you have an abstract for a scientific paper: internal mechanism leading to the emergence of the widely occurring @xmath0 noise still remains an open issue . in this paper
we investigate the distinction between internal time of the system and the physical time as a source of @xmath0 noise . after demonstrating the appearance of @xmath0 noise in the earlier proposed point process model , we generalize it starting from a stochastic differential equation which describes a brownian - like motion in the internal ( operational ) time .
we consider this equation together with an additional equation relating the internal time to the external ( physical ) time .
we show that the relation between the internal time and the physical time that depends on the intensity of the signal can lead to @xmath0 noise in a wide interval of frequencies .
the present model can be useful for the explanation of the appearance of @xmath0 noise in different systems .
_ keywords _ : stochastic processes ( theory ) , stochastic processes , current fluctuations , driven diffusive systems ( theory ) .
And you have already written the first three sentences of the full article: the @xmath0 noise is a random process described by the power spectral density ( psd ) , @xmath1 , roughly proportional to the reciprocal frequency , @xmath0 , i.e. , @xmath2 , with @xmath3 close to @xmath4 .
it was observed first as an excess low - frequency noise in vacuum tubes @xcite , later in condensed matter @xcite and other systems @xcite . the general nature of @xmath0 noise ( named also `` flicker noise '' and `` @xmath0 fluctuations '' ) is up to now the subject of several discussions and investigations , see @xcite for review .
many models have been proposed to explain the origin of @xmath0 noise ..
Please generate the next two sentences of the article | a short discussion about the models and theories of @xmath0 noise is available in the introduction of paper @xcite .
widely used model of @xmath0 noise interprets the spectrum as a superposition of lorentzians with a wide range distribution of relaxation times @xcite . another possibility to model signals and processes featuring @xmath5 noise |
8,711 | Suppose that you have an abstract for a scientific paper: the logarithmic violations of the area law , i.e. an area law " with logarithmic correction of the form @xmath0 , for entanglement entropy are found in both 1d gapless fermionic systems with fermi points and for high dimensional free fermions .
the purpose of this work is to show that both violations are of the same origin , and in the presence of fermi liquid interactions such behavior persists for 2d fermion systems . in this paper
we first consider the entanglement entropy of a toy model , namely a set of decoupled 1d chains of free spinless fermions , to relate both violations in an intuitive way .
we then use multi - dimensional bosonization to re - derive the formula by gioev and klich [ phys .
rev .
lett .
96 , 100503 ( 2006 ) ] for free fermions through a low - energy effective hamiltonian , and explicitly show the logarithmic corrections to the area law in both cases share the same origin : the discontinuity at the fermi surface ( points ) . in the presence of fermi liquid ( forward scattering )
interactions , the bosonized theory remains quadratic in terms of the original local degrees of freedom , and after regularizing the theory with a mass term we are able to calculate the entanglement entropy perturbatively up to second order in powers of the coupling parameter for a special geometry via the replica trick . we show that these interactions do not change the leading scaling behavior for the entanglement entropy of a fermi liquid . at higher orders , we argue that this should remain true through a scaling analysis . .
And you have already written the first three sentences of the full article: the study of entanglement , which is one of the most fundamental aspects of quantum mechanics , has lead to and is still leading to much important progress and applications in different fields of modern physics such as quantum information@xcite , condensed matter physics@xcite , etc .. to name a few , it has lead to better undertanding of density matrix renormalization group ( dmrg)@xcite ; it has also been proposed to be a tool for the characterization of certain topological phases@xcite . among various ways of quantifying entanglement , in condensed matter or many - body physics efforts
have mainly focused on the bipartite block entanglement entropy ( von neumann entropy ) and its generalizations ( rnyi or tsallis entropy ) .
it has become increasingly useful in characterizing phases@xcite and phase transitions@xcite ..
Please generate the next two sentences of the article | the area law@xcite is one of the most important results on entanglement entropy : it states that the entanglement entropy is proportional to the area of the surface separating two subsystems .
however , thus far there are two important classes of systems that violate the area law : in gapless one dimensional ( 1d ) systems , a logarithmic divergence@xcite is found where according to the area law the entanglement entropy should saturate as the size of the subsystem grows ; in higher dimensions , for free fermions the area law is found to be corrected by a similar logarithmic factor @xmath1@xcite , where @xmath2 is the linear dimension of the subsystem . in this work , |
8,712 | Suppose that you have an abstract for a scientific paper: an optical shutter based on charged particles is presented .
the output light intensity of the proposed device has an intrinsic dependence on the interparticle spacing between charged particles , which can be controlled by varying voltages applied to the control electrodes .
the interparticle spacing between charged particles can be varied continuously and this opens up the possibility of particle based displays with continuous grayscale . .
And you have already written the first three sentences of the full article: the flexibility and bistability are the two key points in the next generation display technologies .
the flexibility implies the display would be thin , lightweight , and ultimately , paper like , meaning it would be cheap enough to be disposable .
the bistability implies the technology would be ecologically friendly . in the bistable display.
Please generate the next two sentences of the article | , the image does not need to be refreshed until rewritten and , therefore , a low level of power consumption is expected for still images .
unfortunately , for motion pictures , the bistability has no advantages in power savings over nonbistable technologies such as liquid crystal displays ( lcds ) , plasma display panels ( pdps ) , and displays based on organic light emitting diodes commonly referred to as oleds . |
8,713 | Suppose that you have an abstract for a scientific paper: we consider a simple toy model of a regular bouncing universe .
the bounce is caused by an extra time - like dimension , which leads to a sign flip of the @xmath0 term in the effective four dimensional randall sundrum - like description .
we find a wide class of possible bounces : big bang avoiding ones for regular matter content , and big rip avoiding ones for phantom matter .
focusing on radiation as the matter content , we discuss the evolution of scalar , vector and tensor perturbations .
we compute a spectral index of @xmath1 for scalar perturbations and a deep blue index for tensor perturbations after invoking vacuum initial conditions , ruling out such a model as a realistic one .
we also find that the spectrum ( evaluated at hubble crossing ) is sensitive to the bounce .
we conclude that it is challenging , but not impossible , for cyclic / ekpyrotic models to succeed , if one can find a regularized version . .
And you have already written the first three sentences of the full article: recently , bouncing models of the universe were revived in the framework of string cosmology @xcite , since it is possible to generate a scale invariant spectrum of density fluctuations in the pre - bounce phase .
specific realizations are e.g. cyclic / ekpyrotic models of the universe @xcite or the pre - big bang scenario @xcite .
the main problem for such models to succeed lies in the fact that the bounce itself is often singular in the models studied so far @xcite ..
Please generate the next two sentences of the article | this makes matching conditions a necessity @xcite which are , unfortunately , rather ambiguous .
in addition , fluctuations often become non perturbative near a singularity @xcite . in the few toy models of regular bouncing cosmologies known in the literature |
8,714 | Suppose that you have an abstract for a scientific paper: chord diagrams on circles and their intersection graphs ( also known as _ circle graphs _ ) have been intensively studied , and have many applications to the study of knots and knot invariants , among others . however , chord diagrams on more general graphs have not been studied , and are potentially equally valuable in the study of spatial graphs .
we will define chord diagrams for planar embeddings of planar graphs and their intersection graphs , and prove some basic results . then , as an application , we will introduce gauss codes for immersions of graphs in the plane and give algorithms to determine whether a particular crossing sequence is realizable as the gauss code of an immersed graph . .
And you have already written the first three sentences of the full article: classically , a _ chord diagram _ is a collection of chords of a circle ; the intersection graph for these chords is called a _ circle
graph_. circle graphs have been intensively studied in graph theory , with classifications given by even and itai @xcite and bouchet @xcite , among others . in recent years ,
interest in chord diagrams has spread to topologists as part of the theory of finite type knot and link invariants @xcite , as well as the theory of virtual knots @xcite ..
Please generate the next two sentences of the article | a natural extension of knot theory is to look at spatial embeddings of more complex graphs , and it is natural to ask whether some analogue of chord diagrams could be equally useful in this context .
the goal of this paper is to define a reasonable notion of chord diagram for general graphs , and to construct some tools to study them . in particular |
8,715 | Suppose that you have an abstract for a scientific paper: exclusive semileptonic @xmath0 decays into excited charmed mesons are investigated at order @xmath1 in the heavy quark effective theory .
differential decay rates for each helicity state of the four lightest excited @xmath2 mesons ( @xmath3 , @xmath4 , @xmath5 , and @xmath6 ) are examined . at zero recoil ,
@xmath1 corrections to the matrix elements of the weak currents can be written in terms of the leading isgur - wise functions for the corresponding transition and meson mass splittings .
a model independent prediction is found for the slope parameter of the decay rate into helicity zero @xmath3 at zero recoil .
the differential decay rates are predicted , including @xmath1 corrections with some model dependence away from zero recoil and including order @xmath7 corrections . ratios of various exclusive branching ratios are computed .
matrix elements of the weak currents between @xmath0 mesons and other excited charmed mesons are discussed at zero recoil to order @xmath1 .
these amplitudes vanish at leading order , and can be written at order @xmath1 in terms of local matrix elements . applications to @xmath0 decay sum rules and factorization are presented . .
And you have already written the first three sentences of the full article: heavy quark symmetry @xcite implies that in the @xmath8 limit matrix elements of the weak currents between a @xmath0 meson and an excited charmed meson vanish at zero recoil ( where in the rest frame of the @xmath0 the final state charmed meson is also at rest ) . however , in some cases at order @xmath1 these matrix elements are not zero @xcite
. since most of the phase space for semileptonic @xmath0 decay to excited charmed mesons is near zero recoil , @xmath9 corrections can be very important .
this paper is concerned with rates for @xmath0 semileptonic decay to excited charmed mesons , including the effects of @xmath1 corrections ..
Please generate the next two sentences of the article | the use of heavy quark symmetry resulted in a dramatic improvement in our understanding of the spectroscopy and weak decays of hadrons containing a single heavy quark , @xmath10 . in the limit where the heavy quark mass goes to infinity , @xmath8 ,
such hadrons are classified not only by their total spin @xmath11 , but also by the spin of their light degrees of freedom ( i.e. , light quarks and gluons ) , @xmath12 @xcite . in this limit hadrons containing a single heavy quark |
8,716 | Suppose that you have an abstract for a scientific paper: a review of the present knowledge on polarized parton distributions is given .
the effects of perturbative evolution on these distributions are discussed qualitatively and a comparison of various recent parametrizations is made .
dtp/95/78 + september 1995 + 1.cm * present status of polarized * + + t. gehrmann and w.j .
stirling + + _ talk given at the workshop on the prospects of spin physics at hera , desy - zeuthen , august 28 - 31 , 1995 _ .
And you have already written the first three sentences of the full article: a series of precision measurements @xcite of the polarized structure function @xmath0 off proton and deuteron targets has considerably improved our knowledge on the spin structure of the nucleon over the last two years . in combination with several older measurements @xcite
, these experiments now cover an @xmath1-range of @xmath2 , although the @xmath3 range for fixed @xmath1 is still rather restricted . in the ` naive ' parton model @xmath4
can , like the unpolarized structure function @xmath5 , be expressed in terms of the probability distributions for finding quarks with spin parallel or antiparallel to the longitudinally polarized parent proton : @xmath6 \\ g_1(x , q^2 ) & = & \frac{1}{2 } \sum_q\ ; e_q^2\ ; [ \delta q(x ) + \delta\bar q(x ) ] \ ; , \label{naiveg1}\end{aligned}\ ] ] where @xmath7 furthermore , the naive parton model predicts exact scaling behaviour for the above distributions , i.e. independence of the @xmath3 scale of the measurement ..
Please generate the next two sentences of the article | these distributions are intrinsic , nonperturbative features of the nucleon , and can therefore at present only be determined from a fit to the structure function data .
some insight can however be gained from thermodynamical models @xcite or from the light - cone wavefunctions of partons in the nucleon @xcite . |
8,717 | Suppose that you have an abstract for a scientific paper: in a new hi imaging survey of virgo galaxies ( viva : vla imaging of virgo galaxies in atomic gas ) , we find 7 spiral galaxies with long hi tails .
the morphology varies but all the tails are extended well beyond the optical radii on one side .
these galaxies are found in intermediate - low density regions ( @xmath0 mpc in projection from m87 ) .
the tails are all pointing roughly away from m87 , suggesting that these tails may have been created by a global cluster mechanism .
while the tidal effects of the cluster potential are too small , a rough estimate suggests that simple ram - pressure stripping indeed could have formed the tails in all but two cases .
at least three systems show hi truncation to within the stellar disk , providing evidence for a gas - gas interaction .
although most of these galaxies do not appear disturbed optically , some have close neighbors , suggesting that tidal interactions may have moved gas outwards making it more susceptible to the icm ram - pressure or viscosity .
indeed , a simulation study of one of the tail galaxies , ngc 4654 , suggests that the galaxy is most likely affected by the combined effect of a gravitational interaction and ram - pressure stripping .
we conclude that these one - sided hi tail galaxies have recently arrived in the cluster , falling in on highly radial orbits .
it appears that galaxies begin to lose their gas already at intermediate distances from the cluster center through ram - pressure or turbulent viscous stripping and tidal interactions with neighbours , or a combination of both . .
And you have already written the first three sentences of the full article: the density - morphology relation @xcite , indicating an increasing elliptical and s0 population fraction with increasing density , has been known to exist over six orders of magnitude in galaxy density @xcite .
it is only recently that large surveys have shown just how smoothly the galaxy properties change with galaxy density .
for example @xcite find that gas deficiency gradually decreases out to two abell radii from the cluster center and @xcite and @xcite find that the star formation rate depends on local galaxy density ..
Please generate the next two sentences of the article | these results have led to the concept that galaxies may already be affected by their environment well before they fall into the dense cluster core ( _ pre - processing _ ) . while many processes have been suggested to affect galaxies in the cluster environment such as ram - pressure stripping @xcite , starvation @xcite , harassment @xcite and tidal distortions due to the cluster potential and galaxy - galaxy interactions @xcite , it is still an open question what would affect the galaxies in the lower density outskirts of the clusters .
recently @xcite studied one such case , ngc 4522 , which is at a large projected distance from the center of virgo , yet appears to be undergoing ram - pressure stripping due to bulk motions of the icm , as the m49 subcluster is merging with virgo proper . in our new vla hi survey of the virgo cluster , we find candidates that appear to be feeling the cluster influence for the first time in the outskirts of the cluster . a number of galaxies located at intermediate distances from m87 reveal long gas tails , all pointing roughly away from the cluster center . here |
8,718 | Suppose that you have an abstract for a scientific paper: high resolution observations of solar filaments suggest the presence of groups of prominence threads , i.e. the fine - structures of prominences , which oscillate coherently ( in phase ) .
in addition , mass flows along threads have been often observed . here
, we investigate the effect of mass flows on the collective fast and slow nonadiabatic magnetoacoustic wave modes supported by systems of prominence threads .
prominence fine - structures are modeled as parallel , homogeneous and infinite cylinders embedded in a coronal environment .
the magnetic field is uniform and parallel to the axis of threads .
configurations of identical and nonidentical threads are both explored .
we apply the @xmath0-matrix theory of acoustic scattering to obtain the oscillatory frequency and the eigenfunctions of linear magnetosonic disturbances .
we find that the existence of wave modes with a collective dynamics , i.e. those that produce significant perturbations in all threads , is only possible when the doppler - shifted individual frequencies of threads are very similar .
this can be only achieved for very particular values of the plasma physical conditions and flow velocities within threads . .
And you have already written the first three sentences of the full article: prominences / filaments are fascinating coronal magnetic structures , whose dynamics and properties are not well - understood yet .
the long life of the so - called quiescent prominences ( several weeks ) suggests that the cool and dense prominence material is maintained against gravity and thermally shielded from the much hotter and much rarer solar corona by means of some not well - known processes .
however , it is believed that the magnetic field must play a crucial role in both the support and isolation of prominences ..
Please generate the next two sentences of the article | high - resolution observations of solar filaments reveal that they are formed by a myriad of horizontal structures called threads ( e.g. , * ? ? ?
* ) , which have been observed in the spines and barbs of both active region and quiescent filaments @xcite . |
8,719 | Suppose that you have an abstract for a scientific paper: in the minimal @xmath0 gauge model with a global @xmath1 ( @xmath2 ) symmetry and a discrete @xmath3 symmetry , it is found that the interplay between neutrinos and charged leptons contained in triplets of @xmath4=(@xmath5 , @xmath6 , @xmath7 ) ( @xmath8=1,2,3 ) naturally leads to the large mixing angle ( lma ) msw solution .
the model includes two ( anti)sextet higgs scalars , @xmath9 with @xmath10=0 and @xmath11 with @xmath10=2 , which , respectively , couple to @xmath12 for the electron mass and masses of atmospheric neutrinos and to @xmath13 for the @xmath14- and @xmath15-masses and one - loop radiative neutrino masses relevant to solar neutrinos .
this mechanism is realized by utilizing an additional residual discrete symmetry supplied by explicitly broken @xmath10 , which guarantees the absence of tree - level neutrino mass terms of the @xmath13-type .
pure rotation effects due to the diagonalization of neutrino and charged - lepton mass matrices are estimated to yield @xmath16 but the radiative effects supersede the rotation effects to yield @xmath17 as the lma solution .
epsf # 1#2#3#4#1 * # 2 * ( # 4 ) # 3 # = `` 0023 $ = ' ' 0024 % = `` 0025 = ' ' 705c = `` 336e = ' ' 336f = `` 331a = ' ' 331b = `` 3328 = ' ' 3329 = " 0350 .
And you have already written the first three sentences of the full article: in the recent report on the detailed analysis of solar neutrino oscillations @xcite done by the super - kamiokande collaboration @xcite , it has been suggested that solutions with large mixing angles are favored while solutions with small mixing angles are disfavored at the 95@xmath18 confidence level .
neutrino oscillations controlled by such large mixing angle have also been observed and confirmed for atmospheric neutrinos @xcite .
both observed oscillations are characterized by the same property of neutrino mixings , namely , large neutrino mixings , which are theoretically consistent with bimaximal mixing scheme @xcite ..
Please generate the next two sentences of the article | the difference arises in their oscillation scales denoted by @xmath19 for atmospheric neutrinos and @xmath20 for solar neutrinos , which are specified by @xmath21 ev@xmath22 and @xmath23 ev@xmath22 , thereby , indicating a hierarchy of @xmath24 .
neutrino oscillations arise for massive neutrinos @xcite . |
8,720 | Suppose that you have an abstract for a scientific paper: the chemical composition of exoplanet host stars is an important factor in understanding the formation and characteristics of their orbiting planets .
the best example of this to date is the planet - metallicity correlation .
other proposed correlations are thus far less robust , in part due to uncertainty in the chemical history of stars pre- and post - planet formation . binary host stars of similar type present an opportunity to isolate the effects of planets on host star abundances . here
we present a differential elemental abundance analysis of the xo-2 stellar binary , in which both g9 stars host giant planets , one of which is transiting .
building on our previous work , we report 16 elemental abundances and compare the @xmath0(xo-2n xo - s ) values to elemental condensation temperatures .
the @xmath0(n - s ) values and slopes with condensation temperature resulting from four different pairs of stellar parameters are compared to explore the effects of changing the relative temperature and gravity of the stars .
we find that most of the abundance differences between the stars depend on the chosen stellar parameters , but that fe , si , and potentially ni are consistently enhanced in xo-2n regardless of the chosen stellar parameters .
this study emphasizes the power of binary host star abundance analysis for probing the effects of giant planet formation , but also illustrates the potentially large uncertainties in abundance differences and slopes induced by changes in stellar temperature and gravity . .
And you have already written the first three sentences of the full article: the first indication that stellar composition plays a role in , and may be affected by , the formation of planets was the enhanced metallicity ( parameterized as [ fe / h]=log(n@xmath1/n@xmath2 ) - log ( n@xmath1/n@xmath2)@xmath3 ) of solar - type exoplanet host stars ( gonzalez 1997 ) . while initially suggested as a sign of accretion of hydrogen - depleted material onto the star , the planet - metallicity correlation is now established as a mostly primordial effect ( e.g. , santos et al.2004 ; fischer & valenti 2005 ) .
recently , the correlation was shown to be dependent on planet mass ( e.g. , sousa et al .
2008 ; ghezzi et al ..
Please generate the next two sentences of the article | 2010 ) , being the weakest for terrestrial - sized planets ( e.g. , buchhave et al .
if host star metallicity is considered a proxy for heavy element concentration in the protoplanetary disk , this planet mass dependence seems to support the core accretion process of planet formation , as a larger concentration of heavy elements is needed to form giant planet cores ( @xmath410 m@xmath5 ; ida & lin 2004 ) rapidly enough to allow time for gaseous envelope accretion ( @xmath6100 m@xmath5 ; pollack et al . |
8,721 | Suppose that you have an abstract for a scientific paper: spectra , position , magnitudes and colors are presented for 485 faint ( @xmath0 ) emission line objects selected with the ultraviolet - excess ( uvx ) criterion on a area of 24.6 deg@xmath1 in the south galactic pole .
the objects were selected from the analysis of pixel - to - pixel stacking of cosmos scans of ukst u j and r plates . the candidates were observed with the meudon - eso fiber optics system ( mefos ) at the eso 3.6 m telescope .
429 type 1 agns have been identified ( 373 in the redshift range @xmath2 ) .
this sample has allowed the measure of a difference on the qso clustering evolution in comparison with that found for galaxies ( la franca et al .
1998 ) .
the region is part of the eso imaging survey ( eis ) and of the 2df qso redshift survey . .
And you have already written the first three sentences of the full article: in the last decade the study of the evolution of the qso luminosity function and of the clustering properties of qsos has been based on statistical analysis of even larger qso catalogues . for redshifts
lower than 2.2 the color techniques provide good selection methods .
now days the qso luminosity function evolution at @xmath3 is well established ( e.g. la franca & cristiani 1997 , goldschmidt & miller 1998 ) ..
Please generate the next two sentences of the article | this kind of studies are mainly based on the most statistically significant qso samples such us the durham / aat qso sample ( boyle et al . 1990 ) at faint magnitudes ( @xmath4 ) , and the bright qso survey ( schmidt & green 1983 ) , the large bright qso survey ( hewett et al .
1995 ) , the edinburgh uvx qso survey ( goldschmidt et al . 1992 , miller et al . in prep ) , the homogeneous bright qso survey ( hbqs , cristiani et al . |
8,722 | Suppose that you have an abstract for a scientific paper: the electron transport of different conical valleys is investigated in graphene with extended line - defects .
intriguingly , the electron with a definite incident angle can be completely modulated into one conical valley by a resonator which consists of several paralleling line - defects .
the related incident angle can be controlled easily by tuning the parameters of the resonator .
therefore , a controllable @xmath0 valley polarization , as well as the detection of the valley polarization , can be realized conveniently by tuning the number of line - defects and the distance between two nearest neighbouring line - defects .
this fascinating finding opens a way to realize the valley polarization by line - defects . with the advancement of experimental technologies , this resonator is promising to be realized and thus plays a key role in graphene valleytronics . .
And you have already written the first three sentences of the full article: since the successful fabricating of graphene in 2004 , @xcite its excellent transport properties , @xcite such as the exceptional electron and thermal transport properties at room temperature , have attracted a lot of research interest to apply it in making future electronic devices .
@xcite many ideas and attempts have been going on .
one of the most fundamental and revolutionary attempts is to control the valley degree of freedom to realize the signal s storage and transport.@xcite supposed an achievement of this idea in future , graphene will probably replace all semiconductors in conventional electronics and bring a new era in many fields . before the coming of the new era , there is a long way to improve the control over transport in graphene . inspired by the crucial role of the doping in semiconductor ,.
Please generate the next two sentences of the article | many researchers have studied the effects related to disorder in graphene,@xcite which consists of adsorbed atoms ( or molecules ) , charged impurities , vacancies , or other topological defects .
it is anticipated to modify the transport property of pristine graphene to fulfill the requirement . |
8,723 | Suppose that you have an abstract for a scientific paper: we theoretically propose how to observe topological effects in a generic classical system of coupled harmonic oscillators , such as classical pendula or lumped - element electric circuits , whose oscillation frequency is modulated fast in time . making use of floquet theory in the high frequency limit , we identify a regime in which the system is accurately described by a harper - hofstadter model where the synthetic magnetic field can be externally tuned via the phase of the frequency - modulation of the different oscillators .
we illustrate how the topologically - protected chiral edge states , as well as the hofstadter butterfly of bulk bands , can be observed in the driven - dissipative steady state under a monochromatic drive . in analogy with the integer quantum hall effect , we show how the topological chern numbers of the bands can be extracted from the mean transverse shift of the steady - state oscillation amplitude distribution .
finally we discuss the regime where the analogy with the harper - hofstadter model breaks down . .
And you have already written the first three sentences of the full article: since topological concepts were first introduced to understand the behaviour of electrons in the quantum hall effect @xcite , such ideas have become a powerful theme in condensed matter physics , applicable to a wide - range of different systems @xcite . in topological materials
, the eigenstates making up an electronic energy band can be characterised by nontrivial topological invariants , which are robust against any perturbations that do not close the energy band gaps .
these invariants can be directly related to the existence of remarkable topological edge states localised near the system boundary , which lead , for example , to the robust and precise quantisation of conductance in the quantum hall effect @xcite ..
Please generate the next two sentences of the article | while the study of real materials is usually complicated , the essential physics of various topological phenomena can be captured through simple lattice models .
perhaps the most famous of these is the harper - hofstadter ( hh ) model of a charged electron hopping on a 2d tight - binding square lattice in a uniform magnetic field @xcite . |
8,724 | Suppose that you have an abstract for a scientific paper: we present high resolution ( @xmath0 ) imaging of the proto - planetary nebula afgl 2688 in the co ( j=21 ) line using the iram interferometer .
the observations reveal with unprecedented detail the structure and the kinematics of the gas ejected by the star over the past few hundred years and exemplify the mechanism by which point symmetries are imprinted on the structure of planetary nebulae at early stages of their formation .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: the physical mechanisms which govern the evolution of proto - planetary nebulae ( ppne ) are poorly documented because relatively few objects are known to be in this rapid transition between the agb and planetary nebula phase ( kwok 1993 ) .
the role played by high - velocity winds which interact with the slowly expanding agb envelope has been recognized as essential in the shaping of the planetary nebulae .
however , the details of the interaction and the precise evolution from the symmetric agb envelope to the asymmetries which characterize planetary nebulae are not well understood ..
Please generate the next two sentences of the article | afgl 2688 ( the ` egg nebula ' ) is one of the prime examples of a ppn which has evolved from the agb phase about a hundred years ago ( jura & kroto 1990 ) .
the nearly circular slowly expanding agb envelope ( with a diameter of about @xmath1 ) is shocked by a warm , optically thin , fast wind ( e.g. , young et al . |
8,725 | Suppose that you have an abstract for a scientific paper: we propose a number of variational regularisation methods for the estimation and decomposition of motion fields on the @xmath0-sphere .
while motion estimation is based on the optical flow equation , the presented decomposition models are motivated by recent trends in image analysis .
in particular we treat @xmath1 decomposition as well as hierarchical decomposition .
helmholtz decomposition of motion fields is obtained as a natural by - product of the chosen numerical method based on vector spherical harmonics .
all models are tested on time - lapse microscopy data depicting fluorescently labelled endodermal cells of a zebrafish embryo . .
And you have already written the first three sentences of the full article: motion estimation is a fundamental task for the analysis of spatiotemporal data , the prototypical example of which are sequences of images taken by a camera . the term _ optical flow _ has been coined to designate the apparent motion in such data . its accurate and efficient estimation has been a major topic in the fields of computer vision and image processing for more than 30 years . however , the applicability of optical flow algorithms is by no means limited to flat two - dimensional projections of real world scenes .
the advance of microscopy techniques has led to a particularly promising application of optical flow : cell motion analysis .
reliable optical flow algorithms supplied with microscopy images of sufficiently high spatial and temporal resolution can obviously help understanding cellular dynamics in transparent organisms , see for example @xcite ..
Please generate the next two sentences of the article | the particular dataset we are working with in this article depicts a living zebrafish embryo during early embryogenesis .
main feature of this dataset are the embryo s endodermal cells , which have been labelled with a fluorescent protein and are known to develop on the surface of the zebrafish s spherical yolk , see fig . |
8,726 | Suppose that you have an abstract for a scientific paper: we have studied the x - ray emission within the inner @xmath0150 pc radius of ngc 4151 by constructing high spatial resolution emission line images of blended ovii , oviii , and neix .
these maps show extended structures that are spatially correlated with the radio outflow and optical [ oiii ] emission .
we find strong evidence for jet gas cloud interaction , including morphological correspondences with regions of x - ray enhancement , peaks of near - infrared [ feii ] emission , and optical clouds . in these regions , moreover , we find evidence of elevated neix / ovii ratios ; the x - ray emission of these regions also exceeds that expected from nuclear photoionization .
spectral fitting reveals the presence of a collisionally ionized component .
the thermal energy of the hot gas suggests that @xmath1 of the estimated jet power is deposited into the host interstellar medium through interaction between the radio jet and the dense medium of the circum - nuclear region .
we find possible pressure equilibrium between the collisionally ionized hot gas and the photoionized line - emitting cool clouds .
we also obtain constraints on the extended iron and silicon fluorescent emission .
both lines are spatially unresolved .
the upper limit on the contribution of an extended emission region to the fe k@xmath2 emission is @xmath3 of the total , in disagreement with a previous claim that 65% of the fe k@xmath2 emission originates in the extended narrow line region . .
And you have already written the first three sentences of the full article: multi - wavelength high spatial resolution observations of ngc 4151 ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ; * ? ? ? |
8,727 | Suppose that you have an abstract for a scientific paper: a new satellite based test of special and general relativity is proposed . for the michelson
morley experiment we expect an improvement of at least three orders of magnitude , and for the kennedy thorndike experiment an improvement of more than one order of magnitude .
furthermore , an improvement by two orders of the test of the universality of the gravitational red shift by comparison of an atomic clock with an optical clock is projected .
the tests are based on ultrastable optical cavities , an atomic clock and a comb generator . .
And you have already written the first three sentences of the full article: special relativity ( sr ) and general relativity ( gr ) are at the basis of our understanding of space and time and thus are fundamental for the formulation of physical theories . without sr
we can not explain the phenomena in high energy physics and in particle astrophysics , without gr there is no understanding of the gravitational phenomena in our solar system , of the dynamics of galaxies and of our universe , and , finally , of the physics of black holes .
both theories are linked by the fact that the validity of st is necessary for gr . due to the overall importance of these theories , a persistent effort to improve the experimental tests of their foundations.
Please generate the next two sentences of the article | is mandatory .
modern tests of sr and gr using ultrastable oscillators have been performed on earth @xcite , and an experiment is planned on the international space station @xcite . |
8,728 | Suppose that you have an abstract for a scientific paper: in a diquark - diquark - antiquark picture of pentaquarks , we use two interpolating currents to calculate the mass of the recently measured @xmath0 state in the framework of qcd sum rules .
we show that , even though yielding similar values for @xmath1 ( and close to the experimental value ) , these currents differ from each other in what concerns the strength of the pole , convergence of the ope and sensitivity to the continuum threshold parameter . .
And you have already written the first three sentences of the full article: after the recent discovery of pentaquark states @xcite the central question to be addressed now concerns the structure of these new baryons .
they could be : a ) uncorrelated quarks inside a bag @xcite ; b ) a @xmath2 molecule bound by a van - der waals force @xcite ; c ) a `` @xmath2 '' bound state in which @xmath3 and @xmath4 are not separately in color singlet states @xcite ; d ) a diquark - triquark @xmath5 bound state @xcite and e ) a diquark - diquark - antiquark ( dda ) state .
this last one was advanced by jaffe and wilczek ( jw ) @xcite and is quite appealing because it can explain two unusual features of pentaquarks : their small mass and decay width ..
Please generate the next two sentences of the article | instantons generate strong attractive quark - quark interactions with the formation of low mass diquarks , which , in turn , lead to relatively low mass pentaquarks .
this was verified in @xcite , @xcite and @xcite . moreover , in @xcite , it was shown that the dda configuration may lead to strongly suppressed transition amplitudes ( to meson - baryon states ) for a reasonable choice of its spatial wave function , namely , two separated extended diquark balls overlapping only partially and the antiquark at the center of the system . |
8,729 | Suppose that you have an abstract for a scientific paper: the nuclei that constitute a crystalline lattice , oscillate relative to each other with a very low energy that is not sufficient to penetrate through the coulomb barriers separating them .
an additional energy , which is needed to tunnel through the barrier and fuse , can be supplied by external electromagnetic waves ( x - rays or the synchrotron radiation ) .
exposing to the x - rays the solid compound lid ( lithium - deuteride ) for the duration of 111 hours , we have detected 88 events of the nuclear fusion @xmath0 .
our theoretical estimate agrees with what we observed .
one of possible applications of the phenomenon we found , could be the measurements of the rates of various nuclear reactions ( not necessarily fusion ) at extremely low energies inaccessible in accelerator experiments . .
And you have already written the first three sentences of the full article: fusion of two atomic nuclei is possible if they approach each other to a short distance ( @xmath1 cm ) . to come that close , they need to go through a coulomb barrier of the height of few mev .
the penetration probability for such a barrier at room temperature ( energy of relative motion @xmath2mev ) is practically zero ( @xmath3 @xcite ) , but this probability rapidly grows when the kinetic energy of the nuclei increases .
for example , for the @xmath4 system at the energy of 30kev the penetration probability becomes @xmath5 @xcite ..
Please generate the next two sentences of the article | therefore , the obvious way to fuse the nuclei is to raise the temperature of their mixture . in this way
the so called thermo - nuclear reactions happen in the stellar bodies , in nuclear weapons , and in the tokamak@xcite . |
8,730 | Suppose that you have an abstract for a scientific paper: in this paper , we propose three novel and important methods for the registration of histological images for 3d reconstruction .
first , possible intensity variations and nonstandardness in images are corrected by an intensity standardization process which maps the image scale into a standard scale where the similar intensities correspond to similar tissues meaning .
second , 2d histological images are mapped into a feature space where continuous variables are used as high confidence image features for accurate registration .
third , we propose an automatic best reference slice selection algorithm that improves reconstruction quality based on both image entropy and mean square error of the registration process .
we demonstrate that the choice of reference slice has a significant impact on registration error , standardization , feature space and entropy information .
after 2d histological slices are registered through an affine transformation with respect to an automatically chosen reference , the 3d volume is reconstructed by co - registering 2d slices elastically . .
And you have already written the first three sentences of the full article: 2d imaging methods , such as optical microscopy , are still preferable to 3d imaging methods due to their high level of specificity and high resolution properties .
histological sections ( slices ) obtained through 2d imaging methods provide useful information for the diagnosis or the study of pathology .
3d volume reconstruction from these 2d slices is required in order to fully appreciate anatomical structures @xcite ..
Please generate the next two sentences of the article | typically , a 3d volume is reconstructed by registering ( aligning ) the 2d sections with respect to a chosen reference and stacking successive aligned sections @xcite .
as the acquisition processes of different 2d histological images are performed independently , slice misalignment and deformation is often unavoidable . figure [ img : badslices ] shows examples of histological slices with non - cohorent distortions , tears , hole and missing parts . |
8,731 | Suppose that you have an abstract for a scientific paper: * abstract : * in the framework of a relativistic covariant bethe - salpeter model for the quark - antiquark system we present a renewed determination of the cabbibo - kobayashi - maskawa matrix element @xmath0 . complementing an earlier analysis applied to the whole decay spectrum for @xmath1 we now also employ the `` zero - recoil method '' that uses the end point of the decay spectrum ( @xmath2 ) and is suited for heavy - to - heavy transitions .
the averaged experimental value extracted from the data at zero recoil , @xmath3 , then leads to @xmath4 .
this value is somewhat larger than the one that uses the whole decay spectrum for the model analysis .
we also contrast this result to a nonrelativistic model and to recent experiments on the @xmath5 semileptonic decay . 13.30.ce , 12.39.ki , 12.15.hh , 13.20.he .
And you have already written the first three sentences of the full article: within the standard model the extraction of the cabbibo - kobayashi - maskawa ( ckm ) matrix elements @xmath0 ( and @xmath6 ) is an outstanding topic of @xmath7-meson physics .
several ways have been utilized that are summarized , e.g. , by the particle data group @xcite .
presently , the value of @xmath0 extracted from inclusive decays is somewhat larger than from exclusive decays , e.g. , in @xmath8 ..
Please generate the next two sentences of the article | a fruitful method to extract @xmath0 from exclusive decays is to reparameterize the decay data in such a way that they may be fitted by a smooth ( e.g. , linear ) function @xmath9 of @xmath10 , where @xmath11 , and @xmath12 is the 4-momentum transfer . doing so it is possible to extrapolate to the point of zero recoil of the @xmath13-meson , i.e. , @xmath2 , that is not directly measurable .
this procedure is particularly favored in the context of heavy quark expansion ( hqet ) @xcite but also useful to compare to other approaches since in this context the notion of the whole decay spectrum is not needed to extract @xmath0 . in hqet the value of @xmath14 at zero recoil is normalized up to corrections of order @xmath15 ( where @xmath16 denotes the mass of the @xmath17- or @xmath18-quark ) . |
8,732 | Suppose that you have an abstract for a scientific paper: we propose the implementation of a light source , which can deterministically generate a rich variety of multi - mode quantum states .
the desired states are encoded in the collective population of different ground hyperfine states of an atomic ensemble and converted to multi - mode photonic states by excitation to optically excited levels followed by cooperative spontaneous emission . among our examples of applications ,
we demonstrate how two - photon entangled states can be prepared and implemented in a protocol for reference frame free quantum key distribution and how one - dimensional as well as higher - dimensional cluster states can be produced . .
And you have already written the first three sentences of the full article: quantum states of light are efficient carriers of quantum information with applications in quantum computing , quantum cryptography , and quantum networks .
their most serious drawback is the absence of suitable non - linear interactions which can produce and transform the desired states .
measurement back action presents one means to accommodate the required non - linearities and paves the way for universal quantum computing with the tools of linear optics , but certain resource states such as single - photon states @xcite or superpositions of coherent states @xcite are required , while even more involved states , such as cluster states @xcite , are needed to perform successfully with high probability ..
Please generate the next two sentences of the article | an efficient method to prepare general quantum states of light deterministically would constitute a significant step forward for optical quantum information processing .
there are a number of different strategies to produce non - classical states of light . |
8,733 | Suppose that you have an abstract for a scientific paper: we find that relative locality , a recently proposed planck - scale deformation of special relativity , suffers from the existence of causal loops .
a simple and general construction of such on - shell loop processes is studied .
we then show that even in one of the weakest deformations of the poincar group in relative locality , causality can be violated .
the search for quantum gravity has led to the idea that special relativity should be modified at high energies in such a way that ( modified ) lorentz transformations leave the planck scale invariant .
doubly special relativity ( dsr ) has been proposed as an embodiment of this idea @xcite .
however , it was shown in @xcite that this theory has observer dependent non - localities for distant interactions .
relative locality is a reincarnation of dsr that tries to clarify the issue by proposing a radically different way of thinking about physics .
the birth of relative locality came from the insight that we never directly observe the spacetime we postulate .
our usual picture of spacetime is constructed operationally from the measurements of energies , momenta and times of events@xcite .
the notions that everything shares a universal spacetime and that locality has absolute observer - independent meaning could be unwarranted assumptions . as a theory describing quantum gravity induced modifications to relativistic dynamics of particles , relative locality was proposed at the regime where @xmath0 , while their ratio @xmath1 is held fixed for every observer@xcite .
so effects due to the presence of the planck mass are expected .
some rl phenomology has been studied in @xcite relative locality takes momentum space @xmath2 as primary and formulates classical dynamics on the phase space @xmath3@xcite .
the geometry of momentum space is not preassumed to be that of a linear space but could have curvature , torsion and non - metricity in general , and should be tested by experiments .
there is no global projection that gives a....
And you have already written the first three sentences of the full article: momentum space is assumed to be a manifold @xmath2 with a metric @xmath5 and a connection @xmath6 .
the geodesic distance @xmath7 from the origin to a point @xmath8 is interpreted as the rest mass of a particle with momentum @xmath9 .
the non - linear addition rule of momenta @xmath10 , which should be found experimentally , determines the connection : @xmath11 introduce an inverse operation @xmath12 satisfying @xmath13 which turns incoming momenta into outgoing momenta ..
Please generate the next two sentences of the article | now we can write the conservation law associated with any interaction vertex as a non - linear equation @xmath14 .
for example , a three vertex can be written as @xmath15 . |
8,734 | Suppose that you have an abstract for a scientific paper: in this paper we examine the interaction of @xmath0 , @xmath1 , @xmath2 and @xmath3 states , together with their coupled channels , using a mapping from the light meson sector . the assumption that the heavy quarks act as spectators at the quark level automatically leads us to the results of the heavy quark spin symmetry for pion exchange and reproduces the results of the weinberg tomozawa term , coming from light vector exchanges in the extended local hidden gauge approach . with this dynamics
we look for states dynamically generated from the interaction and find two states with nearly zero width , which we associate to the @xmath4 and @xmath5 states .
the states couple mostly to @xmath2 , which are degenerate with the weinberg tomozawa interaction .
the difference of masses between these two states , with @xmath6 respectively , is due to pion exchange connecting these states to intermediate @xmath0 states .
in addition to these two @xmath7 states , we find three more states with @xmath8 , one of them nearly degenerate in two states of @xmath6 .
furthermore we also find eight more states in @xmath9 , two of them degenerate in @xmath10 , and other two degenerate in @xmath11 . .
And you have already written the first three sentences of the full article: hadron physics in the charm and beauty sectors is booming , with mounting activity in experiments babar , cleo , belle , bes , lhc@xmath12 , cdf @xcite and theory @xcite .
one of the issues that has attracted much attention is the finding of hadronic states which can not be interpreted in the conventional picture of @xmath13 for mesons and @xmath14 for baryons .
multiquark states , hybrids or hadronic molecules have been suggested in several works @xcite ..
Please generate the next two sentences of the article | the molecular picture stands on firm grounds once the use of chiral unitary theory in the light quark sector , or its extension through the local hidden gauge approach , has shown that many mesonic and baryonic resonances are dynamically generated from the interaction of more elementary hadron components @xcite .
concerning baryonic resonances with charm or hidden charm , work on molecules has been done in refs . |
8,735 | Suppose that you have an abstract for a scientific paper: based on the interaction between a three - level system and a microtoroidal resonator , we present a scheme for long - distance quantum communication in which entanglement generation with near 0.5 success probability and swaps can be implemented by accurate state detection via measuring about 100 photons . with this scheme the average time of successful entanglement distribution over 2500 km with high fidelity
can be decreased to only about 30 ms , by 7 orders of magnitude smaller compared with famous duan - lukin - cirac - zoller ( dlcz ) protocol [ l .- m .
duan _
et al .
_ nature ( london ) * 414 * , 413 ( 2001 ) ] . in quantum information
science @xcite , the entanglement distributed over quantum networks is a crucial requisite for metrology @xcite , quantum computation @xcite , and communication @xcite .
quantum communication promises completely secure transmission of keys with the ekert protocol @xcite and exact transfer of quantum states by quantum teleportation @xcite . because of losses and other noises in quantum channels , the communication fidelity dwindles exponentially with the channel length . in principle , this problem can be overcome by applying quantum repeaters @xcite , of which the basic principle consists of separating the full distance into shorter elementary links and entangling the links with quantum swaps @xcite .
one kind of quantum repeater protocols based on single or sub - photon coherent state transmission may have high initial fidelity of entanglement but have low successful entangling event @xcite .
a protocol of specific importance for long - distance quantum communication based on collective excitations in atomic ensembles has been proposed in a seminal paper of duan _ et al .
_ @xcite .
after that considerable efforts have been devoted along this line @xcite .
another kind of protocols using bright pulses may have high successful entangling rate but low initial entanglement fidelity@xcite .
does there exist a scheme through which we may have both....
And you have already written the first three sentences of the full article: this work was supported by the state key programs for basic research of china ( 2005cb623605 and 2006cb921803 ) , and by national foundation of natural science in china grant nos .
10474033 and 60676056 .
p. zoller _ et al ..
Please generate the next two sentences of the article | j. d * 36 * , 203 ( 2005 ) . v. giovannetti _
_ , science * 306 * , 1330 ( 2004 ) . |
8,736 | Suppose that you have an abstract for a scientific paper: unevenly spaced time series are common in astronomy because of the day - night cycle , weather conditions , dependence on the source position in the sky , allocated telescope time , corrupt measurements , for example , or be inherent to the scanning law of satellites like _ hipparcos _ and the forthcoming _ gaia_. weighting scheme , adapting to the sampling density and noise level , time series from the _ hipparcos _ periodic catalogue led to significant improvements in the overall accuracy and precision of the estimators with respect to the unweighted counterparts and those weighted by inverse - squared uncertainties .
automated classification procedures employing statistical parameters weighted by the suggested scheme confirmed the benefits of the improved input attributes .
the classification of eclipsing binaries , mira , rr lyrae , delta cephei and alpha@xmath0 canum venaticorum stars employing exclusively weighted descriptive statistics achieved an overall accuracy of 92 per cent , about 6 per cent higher than with unweighted estimators .
[ firstpage ] methods : data analysis methods : statistical stars : variables : general . .
And you have already written the first three sentences of the full article: a significant number of studies were devoted to the estimation of power spectra and modelling of irregularly sampled time series ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ) . the descriptive statistics such as the mean , variance , higher central moments and robust equivalents
: they can summarize essential features of signals in a few numbers employing straightforward computations , which makes them excellent precursors of more detailed analyses like modelling and classification . |
8,737 | Suppose that you have an abstract for a scientific paper: we present a derivation of the low energy lagrangian governing the dynamics of the spin degrees of freedom in a spinor bose condensate , for any phase in which the average magnetization vanishes .
this includes all phases found within mean - field treatments except for the ferromagnet , for which the low energy dynamics has been discussed previously .
the lagrangian takes the form of a sigma model for the rotation matrix describing the local orientation of the spin state of the gas .
= 1 .
And you have already written the first three sentences of the full article: in recent years the field of ultracold atomic physics has attracted the attention of a great many condensed matter theorists , largely due to the prospect of finding novel realizations of many - body systems .
part of the appeal doubtless lies in the exquisite experimental control that may be exercised over the parameters of a system in which many of the complicating factors familiar from the solid state ( disorder , phonons , etc . )
are absent ..
Please generate the next two sentences of the article | intrinsic _ aspects of ultracold atomic gases not dependent on the specifics of the experimental setting are qualitatively novel , however , and without antecedent in the study of condensed matter . in this latter category
we may place the possibility of spontaneous ordering of the spin degrees of freedom in a bose gas . |
8,738 | Suppose that you have an abstract for a scientific paper: # 6 plus 1000pt minus 1000pt # 1 # 1= to # 1#2#1#2 # 1#2#3 ^ 2 # 1#2 # 3 # 1#1| # 1| # 1 # 1#1 # 1/ # 1| # 1| # 1#1^ = # 1#2#3 @xmath0 # 1#2#3#4 @xmath1 # 1#2 @xmath2 # 1#2#3#4#5 @xmath3 # 1 # 1@xmath4 = 1.5ex plus 1pt = 11 addtoresetequationsection normalsizesetsizexiipt plus3pt minus3pt@ plus3pt plus3.5pt minus0pt twosidetrue
@=12 0.0 in 0.0 in 6.0 in 8.5 in .7 cm -1 cm .75 in = 11 .
And you have already written the first three sentences of the full article: # 1 ps . @headings oddfootevenfoot oddhead evenheadoddhead # # 1 ps .
@headings = 12 # 1@xmath4
= 11 # 1 ps . @headings oddfootevenfoot oddhead evenheadoddhead # # 1 ps ..
Please generate the next two sentences of the article | @headings # 1#2#3_phys .
lett . _ * # 1*(19#2)#3 # 1#2#3_z . |
8,739 | Suppose that you have an abstract for a scientific paper: we have observed 60 edge - on galaxies in the nir in order to study the stellar distribution in galaxies with box / peanut - shaped bulges .
the much smaller amount of dust extinction at these wavelengths allows us to identify in almost all target galaxies with box / peanut - shaped bulges an additional thin , central component in cuts parallel to the major axis .
this structure can be identified with a bar .
+ the length of this structure scaled by the length of the bulge correlates with the morphologically classified shape of the bulge .
this newly established correlation is therefore mainly interpreted as the projection of the bar at different aspect angles .
galaxies with peanut bulges have a bar seen nearly edge - on and the ratio of bar length to thickness , @xmath0 , can be directly measured for the first time .
in addition , the correlation of the boxiness of bulges with the bar strength indicates that the bar characteristic could partly explain differences in the bulge shape .
furthermore , a new size relation between the box / peanut structure and the central bulge is found .
our observations are discussed in comparison to a n - body simulation for barred galaxies ( pfenniger & friedli @xcite ) .
we conclude that the inner region of barred disk galaxies are build up by three distinct components : the spheroidal bulge , a thin bar , and a b / p structure most likely representing the thick part of the bar . .
And you have already written the first three sentences of the full article: our statistical study of @xmath11350 edge - on galaxies derived from the rc3 ( _ third reference catalogue of bright galaxies _ , de vaucouleurs et al .
@xcite ) ( ltticke et al .
@xcite , hereafter paper i ) has revealed that 45% of all bulges ( s0-sd galaxies ) are box- and peanut - shaped ( b / p ) ..
Please generate the next two sentences of the article | this high frequency must be considered in a theory of bulge formation and especially in scenarios explaining the formation process of b / p bulges .
currently discussed theories of bulge formation are primordial or secular evolution scenarios . while monolithic collapse ( eggen et al . @xcite ( els ) ) , clumpy collapse ( kauffmann et al . |
8,740 | Suppose that you have an abstract for a scientific paper: in this work , we consider the problem of boundary stabilization for a quasilinear @xmath0 system of first - order hyperbolic pdes . we design a new full - state feedback control law , with actuation on only one end of the domain , which achieves @xmath1 exponential stability of the closed - loop system .
our proof uses a backstepping transformation to find new variables for which a strict lyapunov function can be constructed .
the kernels of the transformation are found to verify a goursat - type @xmath2 system of first - order hyperbolic pdes , whose well - posedness is shown using the method of characteristics and successive approximations .
once the kernels are computed , the stabilizing feedback law can be explicitly constructed from them .
nonlinear hyperbolic systems , boundary conditions , stability , lyapunov function , backstepping , method of characteristics , integral equation , goursat problem tbd .
And you have already written the first three sentences of the full article: in this paper we are concerned with the problem of boundary stabilization for a @xmath0 system of first - order hyperbolic _ quasilinear _ pdes , with actuation at only one of the boundaries .
the quasilinear case is of interest since many relevant physical systems are described by @xmath0 systems of first - order hyperbolic quasilinear pdes , such as open channels @xcite , transmission lines @xcite , gas flow pipelines @xcite or road traffic models @xcite .
this problem has been considered in the past for @xmath0 systems @xcite and even @xmath3 systems @xcite , using the explicit evolution of the riemann invariants along the characteristics ..
Please generate the next two sentences of the article | more recently , an approach using control lyapunov functions has been developed , for @xmath0 systems @xcite and @xmath3 systems @xcite .
these results use only static output feedback ( the output being the value of the state on the boundaries ) . |
8,741 | Suppose that you have an abstract for a scientific paper: we present a theoretical investigation into the two - center interference in aligned h@xmath0 .
the influence of the laser field on the recombination step is investigated by comparing laser - induced harmonic generation with harmonic generation from field - free collisions of gaussian wave packets with the core .
we find that for different gaussian wave packets colliding with the molecule , the interference minimum occurs at the same alignment angle .
the same result is obtained for the laser - induced spectrum when only a single electronic trajectory per harmonic contributes . when multiple electronic trajectories contribute , we find an effect on the minimum position because the interference between short and long trajectories is alignment - dependent . the two - center interference and the influence of the coulombic potential
are clearly seen not only in the harmonic intensity and phase but also in the polarization direction and ellipticity .
we observe significant ellipticity of the emitted radiation around the two - center interference minimum . .
And you have already written the first three sentences of the full article: when a gas of atoms or molecules is subjected to a strong laser field , high - harmonic generation ( hhg ) takes place @xcite .
this process converts many of the laser photons into a single high - frequency photon in the extreme ultraviolet ( xuv ) or soft x - ray regime .
the generation process can be understood in terms of the three - step model @xcite ..
Please generate the next two sentences of the article | first , the electron tunnels out under the influence of the laser field , and then it propagates freely in the laser field and can be driven back to the nucleus , where it can finally recombine .
hhg has been used to generate coherent xuv radiation @xcite . |
8,742 | Suppose that you have an abstract for a scientific paper: we present an iterative scheme , reminiscent of the multigrid method , to solve large boundary value problems with probabilistic domain decomposition ( pdd ) . in it ,
increasingly accurate approximations to the solution are used as control variates in order to reduce the monte carlo error of the following iterates resulting in an overall acceleration of pdd for a given error tolerance .
the key ingredient of the proposed algorithm is the ability to approximately predict the speedup with little computational overhead and in parallel .
besides , the theoretical framework allows to explore other aspects of pdd , such as stability .
one numerical example is worked out , yielding an improvement of between one and two orders of magnitude over the previous version of pdd .
* keywords : * pdd , domain decomposition , scalability , high - performance supercomputing , variance reduction , feynman - kac formula . .
And you have already written the first three sentences of the full article: * probabilistic vs. deterministic domain decomposition . * in the solution of large boundary value problems ( bvps ) arising in realistic applications ( such as airfoil simulation or weather forecast ) , the discretization of the bvp on a domain @xmath0 leads to algebraic systems of equations that can only be solved on a parallel computer with @xmath1 processors .
not only does parallelization require multiple processors but also parallel algorithms .
the classical schwarz alternating method @xcite is the best known of the state - of - the - art algorithms which we will refer to as deterministicand serves to illustrate the difficulty that they all face ..
Please generate the next two sentences of the article | the idea is to divide @xmath0 into a set of @xmath2 overlapping subdomains , @xmath3 , and have processor @xmath4 solve the restriction of the partial differential equation ( pde ) to the subdomain @xmath5 .
but because the solution is not known in the first place , an initial guess has to be made at start , in order to give processor @xmath4 a well - posed ( yet incorrect ) problem . |
8,743 | Suppose that you have an abstract for a scientific paper: an analysis of the photometric observations of the light curves of the five large amplitude , irregularly pulsating stars r umi , rs cyg , v cvn , ux dra and sx her is presented .
first , multi - periodicity is eliminated for these pulsations , they are not caused by the excitation of a small number of pulsation modes with constant amplitudes .
next , on the basis of energetics we also eliminate stochasticity as a cause , leaving low dimensional chaos as the only alternative .
we then use a global flow reconstruction technique in an attempt to extract quantitative information from the light curves , and to uncover common physical features in this class of irregular variable stars that straddle the rv tau to the mira variables .
evidence is presented that the pulsational behavior of r umi , rs cyg , v cvn and ux dra takes place in a 4-dimensional dynamical phase space , suggesting that two vibrational modes are involved in the pulsation .
a linear stability analysis of the fixed points of the maps further indicates the existence of a two - mode resonance , similar to the one we had uncovered earlier in r sct : the irregular pulsations are the result of a continual energy exchange between two strongly nonadiabatic modes , a lower frequency pulsation mode and an overtone that are in a close 2:1 resonance .
the evidence is particularly convincing for r umi , rs cyg and v cvn , but much weaker for ux dra .
in contrast , the pulsations of sx her appear to be more complex and may require a 6d space
. psfig # 1 2 2 .
And you have already written the first three sentences of the full article: the five stars considered here are pulsating variables and show the sorts of light curve irregularities that are generally associated with classification as semiregular variables .
the measurements section of the simbad database lists v cvn , r umi , and rs cyg as sra stars , ux dra as srb , and sx her as srd , although conflicting classifications exist .
rs cyg and ux dra are also classified as carbon stars . sx her is earlier in spectral type ( k2 ) than the others ( late m or c ) ..
Please generate the next two sentences of the article | v cvn has been reported to have two closely spaced periods ( loeser et al .
1986 , kiss et al . |
8,744 | Suppose that you have an abstract for a scientific paper: a robust numerical method called the preconditioned bi - conjugate gradient ( pre - bicg ) method is proposed for the solution of radiative transfer equation in spherical geometry . a variant of this method called stabilized preconditioned bi - conjugate gradient ( pre - bicg - stab ) is also presented .
these are iterative methods based on the construction of a set of bi - orthogonal vectors .
the application of pre - bicg method in some benchmark tests show that the method is quite versatile , and can handle hard problems that may arise in astrophysical radiative transfer theory . .
And you have already written the first three sentences of the full article: the solution of transfer equation in spherical geometry remains a classic problem even 75 years after the first attempts by @xcite , who used eddington approximation . in later decades
more accurate methods were given ( see * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * for historical reviews ) .
@xcite , @xcite developed a variable eddington factor method , and computed the solution on rays of constant impact parameter ( tangents to the discrete shells and parallel to line of sight ) in 1d spherical geometry . |
8,745 | Suppose that you have an abstract for a scientific paper: let @xmath0 be a natural number , and let @xmath1 be a set @xmath2:=\{1,2,\dots , n\}$ ] .
we study the problem to find the smallest possible size of a maximal family @xmath3 of subsets of @xmath4 $ ] such that @xmath3 contains only sets whose size is in @xmath1 , and @xmath5 for all @xmath6 , i.e. @xmath3 is an antichain .
we present a general construction of such antichains for sets @xmath1 containing 2 , but not 1 . if @xmath7 our construction asymptotically yields the smallest possible size of such a family , up to an @xmath8 error .
we conjecture our construction to be asymptotically optimal also for @xmath9 , and we prove a weaker bound for the case @xmath10 .
our asymptotic results are straightforward applications of the graph removal lemma to an equivalent reformulation of the problem in extremal graph theory which is interesting in its own right .
* keywords : * extremal set theory , sperner property , maximal antichains , flat antichains .
And you have already written the first three sentences of the full article: let @xmath11 be an integer and @xmath4:=\{1,2,\dots , n\}$ ] . by @xmath12}$ ] we denote the family of all subsets of @xmath4 $ ] and by @xmath13}k$ ] the family of all @xmath14-subsets of @xmath4 $ ] .
a family @xmath15}$ ] is an _ antichain _ if @xmath5 for all distinct @xmath16 .
an antichain @xmath17 is called _ flat _ if it is contained in two consecutive levels of @xmath12}$ ] , i.e. if @xmath18}{k}\cup\tbinom{[n]}{k+1}$ ] for some @xmath14 . more generally , for a subset @xmath19 $ ] , we call @xmath17 a _ @xmath1-antichain _ if it contains only @xmath14-sets with @xmath20 , i.e. @xmath21 where @xmath22}{k}$ ] . the _ dual _ @xmath23 of a family of sets @xmath24 is the collection @xmath25 of subsets of @xmath26 $ ] given by @xmath27\ : \ i \in a_j\}$ ] for @xmath28 $ ] ..
Please generate the next two sentences of the article | it is well known that a family of sets @xmath17 is an antichain if and only if its dual @xmath23 is a _ completely separating system _ ( css ) : a css is a collection @xmath29 of blocks of @xmath4 $ ] such that for each @xmath30 $ ] there are blocks @xmath31 with @xmath32 and @xmath33 .
the dual of a flat antichain on @xmath13}{k } \cup \binom{[n]}{k-1}$ ] is a _ fair css _ : |
8,746 | Suppose that you have an abstract for a scientific paper: we have analysed a sample of satellite and primary galaxies in the 2df galaxy redshift survey . in our study
we find a strong statistical evidence of the holmberg effect ( that is a tendency for satellites to avoid regions along the line defined by the primary plane ) within 500 kpc of projected distance to the primary .
this effect is present only when we restrict to objects with radial velocity relative to the primary @xmath0 km / s which correspond approximately to the mean of the distribution .
we explore the dependence of this anisotropy on spectral type ( @xmath1 ) , colours , and luminosities of both primaries and satellites , finding that objects with a low present - day star formation rate present the most significant effect .
cosmology : theory - galaxies : formation - galaxies : evolution . .
And you have already written the first three sentences of the full article: the origin and evolution of structures in the universe can be suitably understood within the hierarchical scenario . in such schemes ,
present - day systems are the result of the aggregation of several sub - structures , and in particular , satellite galaxies can contribute significantly as building blocks of galaxy formation .
however , present - day systems of satellites have evolved since their formation ; and therefore the observations of such systems can provide invaluable information on the formation and evolution of galaxies ..
Please generate the next two sentences of the article | there are several works that explore the characteristics of systems of satellites .
holmberg ( 1969 ) found that the distribution of galaxy satellites presents a lack of objects within @xmath2 of the primary disk plane ( @xmath3 ) . |
8,747 | Suppose that you have an abstract for a scientific paper: the local atomic structure of an amorphous nizr@xmath0 alloy was investigated using the anomalous wide - angle x - ray scattering ( awaxs ) , differential anomalous scattering ( das ) and reverse monte carlo ( rmc ) simulations techniques .
the awaxs measurements were performed at eight different incident photon energies , including some close to the ni and zr k edges . from the measurements
eight total structure factor @xmath1 were derived . using the awaxs data
four differential structure factors @xmath2 were derived , two about the ni and zr edges . the partial structure factors
@xmath3 , @xmath4 and @xmath5 were estimated by using two different methods .
first , the @xmath1 and @xmath2 factors were combined and used in a matrix inversion process .
second , three @xmath1 factors were used as input data in the rmc technique .
the coordination numbers and interatomic distances for the first neighbors extracted from the partial structure factors obtained by these two methods show a good agreement . by using the three - dimensional structure derived from the rmc simulations ,
the bond - angle distributions were calculated and they suggest the presence of distorted triangular - faced polyhedral units in the amorphous nizr@xmath0 structure . we have used the warren chemical short - range order parameter to evaluate the chemical short - range order for the amorphous nizr@xmath0 alloy and for the nizr@xmath0 compound .
the calculated values show that the chemical short - range order found in these two materials is similar to that found in a solid solution . .
And you have already written the first three sentences of the full article: amorphous materials have a great potential for application in technological devices , but their uses are limited due to several factors .
one of them is the difficulty to obtain information about their atomic structures .
since most chemical and physical properties of these materials are defined by the first neighbors , knowledge of their structures becomes necessary ..
Please generate the next two sentences of the article | due to the lack of translational symmetry , the determination of their atomic structures involves the combination of different diffraction and spectroscopic techniques as well as simulations and modeling .
the structure of an amorphous binary alloy is described by three pair correlation functions @xmath6 , which are the fourier transformation of the three partial structure factors @xmath7 . |
8,748 | Suppose that you have an abstract for a scientific paper: the detector material cadmium zinc telluride ( czt ) achieves excellent spatial resolution and good energy resolution over a broad energy range , several kev up to some mev .
presently , there are two main methods to grow czt crystals , the modified high - pressure bridgman ( mhb ) and the high - pressure bridgman ( hpb ) process .
the study presented in this paper is based on mhb czt substrates from the company orbotech medical solutions ltd .
@xcite .
former studies have shown that high - work - function materials on the cathode side reduce the leakage current and therefore improve the energy resolution at lower energies .
none of the studies have emphasized on the anode contact material .
therefore , we present in this paper the result of a detailed study in which for the first time the cathode material was kept constant and the anode material was varied .
we used four different anode materials : indium , titanium , chromium and gold , metals with work - functions between 4.1 ev and 5.1 ev .
the detector size was [email protected]@xmath00.5 @xmath1 with 8@xmath08 pixels and a pitch of 2.46 mm .
the best performance was achieved with the low work - function materials indium and titanium with energy resolutions of 2.0 kev ( at 59 kev ) and 1.9 kev ( at 122 kev ) for titanium and 2.1 kev ( at 59 kev ) and 2.9 kev ( at 122 kev ) for indium .
taking into account the large pixel pitch of 2.46 mm , these resolutions are very competitive in comparison to those achieved with detectors made of material produced with the more expensive conventional hpb method .
we present a detailed comparison of our detector response with 3-d simulations .
the latter comparisons allow us to determine the mobility - lifetime - products ( @xmath2-products ) for electrons and holes .
finally , we evaluated the temperature dependency of the detector performance and @xmath2-products .
for many applications temperature dependence is important , therefore , we extended the scope of our study to....
And you have already written the first three sentences of the full article: cadmium zinc telluride ( czt ) has emerged as the material of choice for the detection of hard x - rays and soft gamma - rays with excellent position and energy resolution and without the need for cryogenic cooling . the high density of czt ( @xmath4 5.76 g/@xmath1 ) and high average atomic number ( @xmath5 50 ) result in high stopping power and in a large cross section for photoelectric interactions .
the main application of czt detectors is the detection of photons in the 10 kev to @xmath61 mev energy range .
czt has a major impact in various fields including medical imaging , homeland security applications , and space - borne x - ray and gamma - ray astronomy . to give a few examples of the latter , the swift mission launched in 2004 carries a wide field of view x - ray telescope for the discovery of gamma - ray bursts ( grbs ) in the energy range from 15 kev to 150 kev @xcite ..
Please generate the next two sentences of the article | this burst alert telescope makes use of the coded mask technique to localize grbs with an accuracy of 1 - 2 arcmin .
it is built out of an array of 32,768 co - planar 2@xmath04@xmath04 mm@xmath7 czt detectors covering a total area of 0.5 m@xmath8 |
8,749 | Suppose that you have an abstract for a scientific paper: the _ zero forcing number _ @xmath0 of a graph @xmath1 is the minimum cardinality of a set @xmath2 of black vertices ( whereas vertices in @xmath3 are colored white ) such that @xmath4 is turned black after finitely many applications of the ( classical ) color change rule " : a white vertex is converted to a black vertex if it is the only white neighbor of a black vertex .
zero forcing number was introduced and used to bound the minimum rank of graphs by the
aim minimum rank special graphs work group " .
we introduce here a probabilistic color change rule ( pccr ) which is a natural generalization of the classical color change rule .
we introduce a theory of probabilistic zero forcing arising out of the pccr ; the theory yields a quantity @xmath5 , which can be viewed as the probability that a graph @xmath1 with an initial black set @xmath6 will be converted entirely to the color black .
we also interpret the evolution of the sample spaces of this theory as a markov process .
we end with a few basic examples illustrating this theory .
zero forcing , probabilistic zero forcing , probabilistic color change rule , markov process , absorbing chains 05d40 , 60j10 , 05c50 , 05c05 + .
And you have already written the first three sentences of the full article: let @xmath7 be a finite , simple , connected , and undirected graph of order @xmath8 . for a vertex @xmath9 ,
the _ open neighborhood of @xmath10 _ is the set @xmath11 , the _ closed neighborhood of @xmath10 _ is the set @xmath12=n_g(v ) \cup \{v\}$ ] , and the _ degree _ of a vertex @xmath10 is @xmath13 ; we drop @xmath1 if it is clear in context .
+ let each vertex of a graph @xmath1 be given either the color black or the color white ..
Please generate the next two sentences of the article | denote by @xmath14 the initial set of black vertices of @xmath1 .
the color change rule " changes the color of a vertex @xmath10 from white to black if @xmath10 is the only white neighbor of a black vertex @xmath15 ; in this case , we say that _ @xmath15 forces @xmath10 _ and write @xmath16 . the initial black set @xmath14 is said to be zero forcing " if , after finitely many applications of the color change rule , all vertices of @xmath1 are forced to black . the zero forcing number of @xmath1 " , @xmath0 , is defined as the minimum of the cardinalities of all zero forcing sets of @xmath1 . |
8,750 | Suppose that you have an abstract for a scientific paper: we study an asymmetric form of two - mode entangled coherent state ( ecs ) , where the two local amplitudes have different values , for testing the bell - clauser - horne - shimony - holt ( bell - chsh ) inequality .
we find that the asymmetric ecss have obvious advantages over the symmetric form of ecss in testing the bell - chsh inequality .
we further study an asymmetric strategy in distributing an ecs over a lossy environment and find that such a scheme can significantly increase violation of the inequality . .
And you have already written the first three sentences of the full article: entangled coherent states ( ecss ) in free - traveling fields @xcite have been found to be useful for various applications such as bell inequality tests @xcite , tests for non - local realism @xcite , quantum teleportation @xcite , quantum computation @xcite , precision measurements @xcite , quantum repeater @xcite and quantum key distribution @xcite .
the ecss can be realized in various systems that can be described as harmonic oscillators and numerous schemes for their implementing have been suggested @xcite .
an ecs in a free - traveling field was experimentally generated using the photon subtraction technique on two approximate superpositions of coherent states ( scss ) @xcite ..
Please generate the next two sentences of the article | a proof - of - principle demonstration of quantum teleportation using an ecs as a quantum channel was performed @xcite .
so far , most of the studies on ecss have considered symmetric types of two - mode states where the local amplitudes have the same value . |
8,751 | Suppose that you have an abstract for a scientific paper: in the cold dark matter ( hereafter cdm ) scenario even isolated density peaks contain a high fraction of small scale clumps having velocities larger than the average escape velocity from the structure .
these clumps populate protoclusters , especially in the peripheral regions , @xmath0 ( where @xmath1 is the filtering scale ) . during the cluster collapse and the subsequent secondary infall , collapsing or infalling clumps ( having @xmath2 )
interact with the quoted _ unbound _ clumps ( or _ high speed clumps _ , as we also call them ) having @xmath3 .
we study the interaction between these two kind of clumps by means of the impulse approximation@xmath4 and we find that the collapse of _ bound _ clumps is accelerated with respect to the homogeneous case ( gunn & gott s model , ref .
2 ) .
the acceleration of the collapse increases with decreasing height of the peak , @xmath5 .
we finally compare the acceleration produced by this effect to the slowing down effect produced by the gravitational interaction of the quadrupole moment of the system with the tidal field of the matter of the neighboring proto - clusters studied in del popolo & gambera@xmath6 . we find that the magnitude of the slowing down effect is larger than the acceleration produced by the effect studied in this paper , only in the outskirts of the cluster .
we want to stress that the one which we study in this paper is also present in an isolated protocluster , being produced by the interaction of the collapsing clumps with the _ unbound _ substructure internal to the collapsing clumps itself while that studied in ref .
3 is produced by substructure external to the density peak . .
And you have already written the first three sentences of the full article: according to the most promising cosmological scenarios , structure formation is traced back to the evolution of primordial density fluctuations .
these fluctuations , originated from quantum fluctuations@xmath7@xmath8@xmath9@xmath10@xmath11@xmath8@xmath12 in an inflationary phase of the early universe , grew up through gravitational instability to a maximum radius @xmath13 . at the time @xmath14 corresponding to maximum expansion , perturbations broke away from the general expansion and at @xmath15 them began to collapse .
hence the collapse of perturbations onto local density maxima of the primordial density field has a key role in structure formation and several studies deal with this problem ..
Please generate the next two sentences of the article | the problem of collapse has been investigated from two points of view , namely : \i ) that of the statistical distribution of the objects formed@xmath12@xmath8@xmath16 \ii ) that of the structure of these objects and its dependence on the statistical properties of the primordial density field@xmath17@xmath8@xmath18@xmath10@xmath19@xmath8@xmath20 @xmath21@xmath8@xmath22@xmath10@xmath23@xmath8@xmath24 @xmath25@xmath8@xmath26@xmath10@xmath27@xmath8@xmath28 @xmath29@xmath8@xmath30@xmath10@xmath31@xmath8@xmath32 @xmath33 . in the spherical accretion model introduced by hoyle and narlikar@xmath34 and applied to clusters of galaxies by gunn & gott@xmath35 , the matter around the core of the perturbation is a homogeneous fluid with zero pressure . if the density inside the perturbation is greater than the critical density , it is bound and shall expand to a maximum radius @xmath36 : @xmath37 where @xmath38 is the initial radius and @xmath39 is the overdensity inside the radius @xmath40 .
such matter shall collapse in a time @xmath41 where @xmath42 is the hubble parameter at the initial time @xmath43 . |
8,752 | Suppose that you have an abstract for a scientific paper: we study corruption as a generalized epidemic process on the graph of social relationships .
the main difference to classical epidemic processes is the strong nonlinear dependence of the transmission probability on the local density of corruption and the mean field influence of the overall corruption in the society .
network clustering and the degree - degree correlation play an essential role in corruption dynamics .
we discuss phase transitions , the influence of the graph structure and the implications for epidemic control .
structural and dynamical arguments are given why strongly hierarchically organized societies like systems with dictatorial tendency are more vulnerable to corruption than democracies .
a similar type of modelling can be applied to other social contagion spreading processes like opinion formation , doping usage , social disorders or innovation dynamics . .
And you have already written the first three sentences of the full article: corruption seems to be an unavoidable part of human social interaction , prevalent in every society at any time since the very beginning of human history till today . in sharp contrast to the high prevalence of corruption in many countries and the rather large literature on political , social and economical aspects of corruption
there is only a small number of attempts to model the dynamics of corruption in a mathematically quantified way .
the modelling approach in these few attempts essentially follows two paths ..
Please generate the next two sentences of the article | the first is in the sense of microeconomics and incorporates game theoretic aspects ( for a recent model in this direction see the book by steinrcken @xcite and the references therein ) or rules for maximizing a certain economically based profit functional ( @xcite@xcite )
. then a set of differential equations for the evolution of the mean corruption is derived and a stability analysis done on that basis . in these models |
8,753 | Suppose that you have an abstract for a scientific paper: we study theoretically the interplay effect of zeeman field and modulated spin - orbit coupling on topological properties of a one - dimensional dimerized lattice , known as su - schrieffer - heeger model .
we find that in the weak ( strong ) modulated spin - orbit coupling regime , trivial regions or nontrivial ones with two pairs of zero - energy states can be turned into nontrivial regions by applying a uniform ( staggered ) perpendicular zeeman field through a topological phase transition .
furthermore , the resulting nontrivial phase hosting a pair of zero - energy boundary states can survive within a certain range of the perpendicular zeeman field magnitude . due to the effective time - reversal , particle - hole , chiral , and inversion symmetries , in the presence of either uniform or staggered perpendicular zeeman field , the topological class of the system is bdi which can be characterized by @xmath0 index .
we also examine the robustness of the nontrivial phase by breaking the underlying symmetries giving rise that inversion symmetry plays an important role . .
And you have already written the first three sentences of the full article: topological phases of matters have attracted a lot of attention in recent years due to discovery of graphene @xcite and topological insulators @xcite .
also , the search for conventional and unconventional topological superconductors , hosting topological phases @xcite , has become one of the growing topics in condensed - matter physics @xcite . as long as underlying symmetries in the topological systems
are preserved , the symmetry protected gapless edge or surface states within gapped bulk states are robust against many forms of perturbations , making relevant requirement for quantum electronic devices and , especially , topological quantum computations @xcite ..
Please generate the next two sentences of the article | one - dimensional ( 1d ) heterostructures @xcite consisting of ingredients such as superconductors , topological insulators , spin - orbit coupled semiconductors and ferromagnets can support topologically nontrivial phases hosting , for instance , non - abelian majorana bound states at zero energy levels @xcite and fractionally charged fermion bound states @xcite . furthermore
, 1d majorana chain has been proposed to include majorana fermions @xcite at its boundaries . |
8,754 | Suppose that you have an abstract for a scientific paper: models of leptonic flavour with discrete symmetries can provide an attractive explanation of the pattern of elements found in the leptonic mixing matrix .
the next generation of neutrino oscillation experiments will allow the mixing parameters to be tested to a new level of precision , crucially measuring the cp violating phase @xmath0 for the first time . in this contribution , we present results of a systematic survey of the predictions of a class of models based on residual discrete symmetries and the prospects for excluding such models at medium- and long - term oscillation experiments .
we place particular emphasis on the complementary role that a future circa @xmath1 km reactor experiment , _
e.g. _ juno , can play in constraining these models . .
And you have already written the first three sentences of the full article: the next generation of neutrino oscillation experiments has the potential to not only determine the remaining unknowns in the pmns matrix but also to measure its parameters with unprecedented precision .
this will mark the beginning of a period of high - precision neutrino physics , where the standard paradigms describing the neutrino sector will be put to proof and theoretical ideas about the origins of neutrino mass and leptonic flavour can be confronted with data .
one of the more popular beyond the standard model ideas applied to the neutrino sector is the introduction of a discrete flavour symmetry ..
Please generate the next two sentences of the article | models based on this principle have been shown to be able to derive the observed structure of the pmns matrix from a small set of assumptions .
these models generally propose a discrete symmetry ( _ e.g. _ @xmath2 or @xmath3 ) which is broken spontaneously , leaving residual symmetries amongst the leptonic mass terms . |
8,755 | Suppose that you have an abstract for a scientific paper: we examine the amplitude of the rotation velocity that can be attributed to the dark matter halos of disk galaxies , focusing on well measured intermediate radii .
the data for 60 galaxies spanning a large range of mass and hubble types , taken together , are consistent with a dark halo velocity @xmath0 with @xmath1 and @xmath2 over the range @xmath3 kpc .
the range in @xmath4 stems from different choices of the stellar mass estimator , from minimum to maximum disk . for all plausible choices of stellar mass , the implied densities of the dark halos are lower than expected from structure formation simulations in @xmath5cdm , which anticipate @xmath6 .
this problem is not specific to a particular type of galaxy or to the innermost region of the halo ( cusp or core ) ; the velocity attributable to dark matter is too low at all radii . .
And you have already written the first three sentences of the full article: the rotation curves of spiral galaxies provide one of the strongest lines of evidence establishing the need for dark matter in the universe ( e.g. , rubin , thonnard & ford 1980 ; bosma 1981 ) . an elaborate paradigm for dark matter
has subsequently developed : @xmath5cdm .
more recent work emphasizes larger scale constraints ( e.g. , tegmark et al ..
Please generate the next two sentences of the article | 2004 ; spergel et al .
an important question is whether this cosmic paradigm provides a satisfactory description of spiral galaxies . |
8,756 | Suppose that you have an abstract for a scientific paper: the intention of this paper is to estimate a bayesian distribution - free chain ladder ( dfcl ) model using approximate bayesian computation ( abc ) methodology .
we demonstrate how to estimate quantities of interest in claims reserving and compare the estimates to those obtained from classical and credibility approaches . in this context , a novel numerical procedure utilising markov chain monte carlo ( mcmc ) , abc and a bayesian bootstrap procedure was developed in a truly distribution - free setting .
the abc methodology arises because we work in a distribution - free setting in which we make no parametric assumptions , meaning we can not evaluate the likelihood point - wise or in this case simulate directly from the likelihood model .
the use of a bootstrap procedure allows us to generate samples from the intractable likelihood without the requirement of distributional assumptions , this is crucial to the abc framework .
the developed methodology is used to obtain the empirical distribution of the dfcl model parameters and the predictive distribution of the outstanding loss liabilities conditional on the observed claims
. we then estimate predictive bayesian capital estimates , the value at risk ( var ) and the mean square error of prediction ( msep ) .
the latter is compared with the classical bootstrap and credibility methods .
claims reserving , distribution - free chain ladder , mean square error of prediction , bayesian chain ladder , approximate bayesian computation , markov chain monte carlo , annealing , bootstrap .
And you have already written the first three sentences of the full article: the distribution - free chain ladder model ( dfcl ) of mack @xcite is a popular model for stochastic claims reserving . in this paper
we use a time series formulation of the dfcl model which allows for bootstrapping the claims reserves .
an important aspect of this model is that it can provide a justification for the classical deterministic chain ladder ( cl ) algorithm which originally was not founded on an underlying stochastic model ..
Please generate the next two sentences of the article | moreover , it allows for the study of prediction uncertainties .
note that there are different stochastic models that lead to the cl reserves ( see for example wthrich - merz @xcite , section 3.2 ) . in the present paper |
8,757 | Suppose that you have an abstract for a scientific paper: trigraph list homomorphism problems ( also known as list matrix partition problems ) have generated recent interest , partly because there are concrete problems that are not known to be polynomial time solvable or @xmath0-complete .
thus while _ digraph _ list homomorphism problems enjoy _ dichotomy _ ( each problem is @xmath0-complete or polynomial time solvable ) , such dichotomy is not necessarily expected for trigraph list homomorphism problems .
however , in this paper , we identify a large class of trigraphs for which list homomorphism problems do exhibit a dichotomy .
they consist of trigraphs with a tree - like structure , and , in particular , include all trigraphs whose underlying graphs are trees .
in fact , we show that for these tree - like trigraphs , the trigraph list homomorphism problem is polynomially equivalent to a related _ digraph _ list homomorphism problem .
we also describe a few examples illustrating that our conditions defining tree - like trigraphs are not unnatural , as relaxing them may lead to harder problems .
trigraph , list homomorphism , matrix partition , trigraph homomorphism , surjective list homomorphism , dichotomy , trigraph tree .
And you have already written the first three sentences of the full article: a _ trigraph _ @xmath1 consists of a set @xmath2 of vertices , and two disjoint sets of directed edges on @xmath3 the set of _ weak edges _
@xmath4 , and the set of _ strong edges _ @xmath5 . if both edge sets @xmath6 , viewed as relations on @xmath3 , are symmetric , we have a _ symmetric _ , or _
undirected _ trigraph ..
Please generate the next two sentences of the article | a weak , respectively strong , edge @xmath7 is called a _ weak _ , respectively _ strong , loop _ at @xmath8 .
the _ adjacency matrix _ of a trigraph @xmath1 , with respect to an enumeration @xmath9 of its vertices , is the @xmath10 matrix @xmath11 over @xmath12 , in which @xmath13 if @xmath14 is not an edge , @xmath15 if @xmath14 is a weak edge , and @xmath16 if @xmath14 is a strong edge . |
8,758 | Suppose that you have an abstract for a scientific paper: theoretical approaches to the photoionization of few - electron atoms are discussed .
these include nonequilibrium greens functions and wave function based approaches . in particular , the multiconfiguration time - dependent hartree - fock method is discussed and applied to a model one - dimensional atom with four electrons .
we compute ground state energies and the time - dependent photoionization by the field a strong laser pulse with two different frequencies in the ultraviolet . .
And you have already written the first three sentences of the full article: in recent years ultrashort , high - harmonic generated vacuum and extreme ultraviolet ( vuv / xuv ) laser pulses have become available .
they open the way towards time - resolved observation of electronic dynamics in plasmas , atoms and condensed matter , for an overview see e.g. @xcite . electronic motion in atoms and relaxation processes can now be studied experimentally on sub - femtosecond time scales , e.g. @xcite , for a recent overview see @xcite .
this creates the need for complementary theoretical investigations ..
Please generate the next two sentences of the article | interaction of laser radiation with matter has been actively studied in recent years using a quantum kinetic theory which was derived using nonequilibrium greens functions ( negf ) methods , e.g. @xcite .
in contrast , application of negf to single atoms has only recently been attempted @xcite . while the ground state properties were very well reproduced , time - dependent calculations describing the ionization dynamics of atoms during and after a laser pulse turned out to be computationally very expensive @xcite . in this paper |
8,759 | Suppose that you have an abstract for a scientific paper: we study finite order invariants of null - homotopic immersions of a closed orientable surface into an aspherical orientable 3-manifold .
we give the foundational constructions , and classify all order one invariants . [ section ] [ thm]lemma [ thm]proposition [ thm]corollary [ thm]definition [ thm]remark .
And you have already written the first three sentences of the full article: finite order invariants of immersions of a closed orientable surface into @xmath0 have been introduced in o , where all order 1 invariants have been classified .
explicit formulae for the majority of order 1 invariants have been given in a , f . all higher order invariants have been classified in h , and the analogue of all the above for non - orientable surfaces has appeared in n. a first step in the study of finite order invariants of immersions of surfaces into general 3-manifolds appears in q where one specific order 1 invariant has been studied . in the present work we study finite order invariants of null - homotopic immersions of a closed orientable surface @xmath1 into an aspherical orientable 3-manifold @xmath2 .
the immersions being null - homotopic will enable us to lift the immersions to the universal covering @xmath3 of @xmath2 , and @xmath2 being aspherical will guarantee a simple form for @xmath4 for discrete subset @xmath5 ..
Please generate the next two sentences of the article | we develop the foundations for the study of finite order invariants in our setting , as has been done in o for the case @xmath6 ( and analogous to chord diagrams and the 1-term and 4-term relations in knot theory ) .
we then classify all order 1 invariants . |
8,760 | Suppose that you have an abstract for a scientific paper: it has been observed that the famous feigenbaum - coullet - tresser period doubling universality has a counterpart for area - preserving maps of @xmath0 .
a renormalization approach has been used in a computer - assisted proof of existence of an area - preserving map with orbits of all binary periods in @xcite and @xcite . as it is the case with all non - trivial universality problems in non - dissipative systems in dimensions more than one , no analytic proof of this period doubling universality exists to date .
we argue that the period doubling renormalization fixed point for area - preserving maps is almost one dimensional , in the sense that it is close to the following hnon - like map : @xmath1 where @xmath2 solves @xmath3 we then give a `` proof '' of existence of solutions of small analytic perturbations of this one dimensional problem , and describe some of the properties of this solution .
the `` proof '' consists of an analytic argument for factorized inverse branches of @xmath2 together with verification of several inequalities and inclusions of subsets of @xmath4 numerically . finally , we suggest an analytic approach to the full period doubling problem for area - preserving maps based on its proximity to the one dimensional . in this respect ,
the paper is an exploration of a possible analytic machinery for a non - trivial renormalization problem in a conservative two - dimensional system . .
And you have already written the first three sentences of the full article: following the pioneering discovery of the feigenbaum - coullet - tresser period doubling universality in unimodal maps @xcite , @xcite , @xcite universality has been demonstrated to be a rather generic phenomenon in dynamics .
such renormalization approach to universality has been very successful in one - dimensional dynamics , and has led to explanation of universality in unimodal maps @xcite , @xcite,@xcite , critical circle maps @xcite , @xcite , @xcite and holomorphic maps with a siegel disks @xcite , @xcite , @xcite . universality has been abundantly observed in higher dimensions , in particular , in two and more dimensional dissipative systems ( cf .
@xcite , @xcite ) , in area - preserving maps , both as the period - doubling universality @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , and as the universality associated with the break - up of invariant surfaces @xcite ,.
Please generate the next two sentences of the article | @xcite , @xcite , @xcite , and in hamiltonian flows @xcite,@xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite .
it has been established that the universal behavior in dissipative and conservative higher dimensional systems is fundamentally different . |
8,761 | Suppose that you have an abstract for a scientific paper: non perturbative results from lattice qcd will be discussed , namely : vacuum condensates and qcd sum rules ; @xmath0 and topology ; confinement of color . .
And you have already written the first three sentences of the full article: qcd is usually quantized perturbatively .
the lagrangean @xmath1 is split into the sum of two terms @xmath2 where @xmath3 describes free quarks and gluons , and @xmath4 their interaction .
then @xmath3 is quantized : the hilbert space is the fock space of free quarks and gluons and the interaction describes scattering between them ..
Please generate the next two sentences of the article | any observable @xmath5 is computed as a power series expansion in the renormalized coupling constant @xmath6 @xmath7 where @xmath8 are finite amplitudes .
the expansion eq(2 ) is not convergent , not even as an asymptotic series@xcite . |
8,762 | Suppose that you have an abstract for a scientific paper: we have measured the dynamics of individual magnetic fluxoids entering and leaving photolithographically patterned thin film rings of the underdoped high - temperature superconductor bi@xmath0sr@xmath0cacu@xmath0o@xmath1 , using a variable sample temperature scanning squid microscope .
these results can be qualitatively described using a model in which the fluxoid number changes by thermally activated nucleation of a pearl vortex in , and transport of the pearl vortex across , the ring wall . .
And you have already written the first three sentences of the full article: although fluxoid quantization in superconductors was first demonstrated experimentally over 40 years ago,@xcite there has recently been a resurgence of interest in fluxoid dynamics in a ring geometry . for example
, it has been proposed that the interacting dipole moments in an array of superconducting rings can provide a model experimental system for studying magnetism in ising antiferromagnets .
@xcite this possibility has become particularly attractive with the development of @xmath2-rings : superconducting rings with an intrinsic quantum mechanical phase change of @xmath2 upon circling the ring , in the absence of supercurrents or externally applied fields ..
Please generate the next two sentences of the article | such @xmath2 phase changes can be produced either by the momentum dependence of an unconventional superconducting order parameter , @xcite or by magnetic interactions in the tunneling region of a josephson weak link in the ring.@xcite @xmath2-rings are an ideal model system for the ising antiferromagnet , since they have a degenerate , time - reversed ground state in the absence of an externally applied magnetic field .
recent progress @xcite has made it possible to reliably make very large closely packed arrays of @xmath2-rings , which show strong antiferromagnetic correlations in their spin " orientations upon cooling in zero magnetic field.@xcite superconducting ring experiments have also been proposed@xcite and performed @xcite to test for the presence of visons " , vortex - like topological excitations which may result from electron fractionalization in the high - t@xmath3 cuprate superconductors . |
8,763 | Suppose that you have an abstract for a scientific paper: it is shown for two electron atoms that ground - state wavefunctions of the form @xmath0 where @xmath1 and @xmath2 are the coordinates of two electrons and @xmath3 , can be made highly accurate by optimizing @xmath4 , @xmath5 and @xmath6 .
this is done by solving a variationally derived equation for @xmath6 for a given @xmath4 and @xmath5 and finding @xmath4 and @xmath5 so that the expectation value of the hamiltonian is minimum . for the set @xmath7 the values for various quantities obtained from the above wavefunction
are compared with those given by @xmath8-parameter wavefunction of koga @xciteand are found to be matching quite accurately(within ppm ) with them . .
And you have already written the first three sentences of the full article: the simplest of many - electron systems are those with two electrons like ions of the helium isoelectronicc series or a harmonium atom . since the schr@xmath9dinger equation for these systems can not be solved analytically , accurate solutions are obtained by using the variational principle for the energy .
thus an approximate parametrized form of the wavefunction is chosen incorporating the effect of electron - electron interactionon in the wavefunction and the expectation value of the hamiltonian ( atomic units are used ) @xmath10 is minimized with respect to the parameters in the wavefunction .
this leads to an optimized approximate wavefunction and the corresponding energy ..
Please generate the next two sentences of the article | the various forms used for the wavefunctions are those by hylleraas@xcite , chandrasekhar@xcite and kinoshita@xcite . as an example of how these forms incorporate the effect of electron - electron interaction
, we consider the chandrasekhar wavefunction for two - electron atom given as @xmath11 where @xmath4 and @xmath5 are the parameters to be optimized and @xmath12 is the normalization constant . |
8,764 | Suppose that you have an abstract for a scientific paper: we review the nature of some well - known phenomena such as volatility smiles , convexity adjustments and parallel derivative markets .
we propose that the market is incomplete and postulate the existence of an intrinsic risk in every contingent claim as a basis for understanding these phenomena . in a continuous time framework
, we bring together the notion of intrinsic risk and the theory of change of measures to derive a probability measure , namely risk - subjective measure , for evaluating contingent claims .
this paper is a modest attempt to prove that measure of intrinsic risk is a crucial ingredient for explaining these phenomena , and in consequence proposes a new approach to pricing and hedging financial derivatives . by adapting theoretical knowledge to practical applications ,
we show that our approach is consistent and robust , compared with the standard risk - neutral approach . implied volatility , convexity adjustment , primary and parallel markets , incomplete markets , intrinsic risk , risk - neutral measure , risk - subjective measure , fair valuation , delta - hedging . .
And you have already written the first three sentences of the full article: this section has two purposes .
firstly , we review some well - known phenomena in order to motivate subsequent developments . after that
, we provide a background of the phenomena with some notation , terminology and notions ..
Please generate the next two sentences of the article | _ * volatility smiles . * _ in a nutshell , vanilla options with different maturities and strikes have different volatilities implied by the well - known formula of @xcite . implied volatility is quoted as the market expectation about the average future volatility of the underlying asset over the remaining life of the option . thus compared to historical volatility it is the forward looking approach . for many years
, practitioners and academics have tried to analyse the volatility smile phenomenon and understand its implications for derivatives pricing and risk management . in @xcite , their link between the real - world and risk - neutral processes of the underlying would be complete by non - traded sources of risk . |
8,765 | Suppose that you have an abstract for a scientific paper: we use 62,185 quasars from the sloan digital sky survey dr5 sample to explore the relationship between black hole mass and luminosity .
black hole masses were estimated based on the widths of their h@xmath0 , mgii , and civ lines and adjacent continuum luminosities using standard virial mass estimate scaling laws .
we find that , over the range @xmath1 , the most luminous low - mass quasars are at their eddington luminosity , but the most luminous high - mass quasars in each redshift bin fall short of their eddington luminosities , with the shortfall of order ten or more at @xmath2 .
we examine several potential sources of measurement uncertainty or bias and show that none of them can account for this effect .
we also show the statistical uncertainty in virial mass estimation to have an upper bound of @xmath3 dex , smaller than the 0.4 dex previously reported .
we also examine the highest - mass quasars in every redshift bin in an effort to learn more about quasars that are about to cease their luminous accretion .
we conclude that the quasar mass - luminosity locus contains a number of new puzzles that must be explained theoretically .
[ firstpage ] black hole physics galaxies : evolution galaxies : nuclei quasars : general accretion , accretion discs .
And you have already written the first three sentences of the full article: supermassive black holes ( smbh ) , with masses between @xmath4 and @xmath5 , are found at the center of nearly every galaxy where there have been sensitive searches .
while we suspect that the seeds for these smbh might all have a common origin , their formation mechanism is not well understood .
many galaxies at redshifts @xmath6 contain quasars , i.e. , smbh in the midst of luminous accretion ..
Please generate the next two sentences of the article | the soltan argument @xcite suggests black hole masses are largely accounted for via growth due to luminous accretion .
there are far fewer quasars at low redshift @xcite , implying that at some point , smbh cease their luminous accretion . |
8,766 | Suppose that you have an abstract for a scientific paper: the disk embedding lemma is a technique underlying the topological classification results in @xmath0-manifold topology for good fundamental groups .
the purpose of this paper is to develop new tools for disk embedding that work up to @xmath1-cobordism , without restrictions on the fundamental group . as an application
we show that a surgery problem gives rise to a collection of capped gropes that fit in the framework of control theory .
[ thm]lemma [ thm]proposition [ thm]corollary [ thm]conjecture [ section ] the disk embedding lemma is a technique underlying the topological classification results in @xmath0-manifold topology .
it is conjectured to fail , in general , when the fundamental group of the @xmath0-manifold is free .
a weaker lemma , disk embedding up to @xmath1-cobordism , would imply @xmath0-dimensional surgery but not the @xmath2-dimensional @xmath1-cobordism conjecture .
recall its statement : * conjecture*. _ suppose @xmath3 is an immersion of a @xmath4-sphere into a @xmath0-manifold @xmath5 , and there is a framed immersed @xmath4-sphere @xmath6 with trivial algebraic self - intersection , and algebraic intersection @xmath7 with @xmath3 .
then there is an @xmath1-cobordism of the immersion @xmath3 to a topological embedding .
_ the advantage of this formulation is the extra flexibility in changing the ambient @xmath0-manifold , which could make it applicable in contexts where the disk embedding lemma in unavailable .
we refer the reader to @xcite for a discussion of the consequences of this conjecture .
it has been established @xcite under an additional assumption that the transverse pair of spheres is @xmath8-null in @xmath5 ( in other words , the inclusion @xmath9 induces the trivial map on fundamental groups . ) the purpose of this paper is to develop new techniques for disk embedding that work up to @xmath1-cobordism , for any fundamental group . after reviewing the foundational material
the construction of @xmath1-cobordisms and splitting of....
And you have already written the first three sentences of the full article: the purpose of this section is to review the construction of @xmath1-cobordisms in @xcite , chapter 6 .
we include it here for convenience of the reader , and also to fix the terminology , since this will be used throughout the paper .
recall that this construction is used in @xcite to prove that a @xmath8-null immersion of a union of transverse pairs , with algebraically trivial intersections , is @xmath1-cobordant to an embedding ..
Please generate the next two sentences of the article | the starting point for the construction is a transverse pair of framed spheres @xmath12 in a @xmath0-manifold @xmath5 .
typically in the applications the transverse pairs have algebraically trivial intersections . |
8,767 | Suppose that you have an abstract for a scientific paper: we present the observed relation between @xmath0 , the cosmic microwave background ( cmb ) temperature decrement due to the sunyaev - zeldovich ( sz ) effect , and @xmath1 , the x - ray luminosity of galaxy clusters .
we discuss this relation in terms of the cluster properties , and show that the slope of the observed @xmath2 relation is in agreement with both the @xmath3 relation based on numerical simulations and x - ray emission observations , and the @xmath4 relation based on observation .
the slope of the @xmath2 relation is also consistent with the @xmath5 relation , where @xmath6 is the cluster total mass based on gravitational lensing observations .
this agreement may be taken to imply a constant gas mass fraction within galaxy clusters , however , there are large uncertainties , dominated by observational errors , associated with these relations . using the @xmath2 relation and the cluster x - ray luminosity function , we evaluate the local cluster contribution to arcminute scale cosmic microwave background anisotropies .
the compton distortion @xmath7-parameter produced by galaxy clusters through sz effect is roughly two orders of magnitude lower than the current upper limit based on _ firas _ observations .
cosmology : observations cosmology : theory galaxies : clusters : general cosmic microwave background .
And you have already written the first three sentences of the full article: the x - ray emission from galaxy clusters has enabled the study of what is assumed to be the largest virialized systems in the universe .
the x - ray electron temperature , @xmath8 , measures the depth of the galaxy cluster potential , while the x - ray luminosity , @xmath1 , emitted as thermal bremsstrahlung by the intracluster plasma , measures primarily the baryonic number density within this potential .
when combined with the fact that the electron temperature is a robust estimator of the galaxy cluster total mass , @xmath6 , the x - ray emission observations can be used in cosmological studies to derive constraints on the power spectrum of the initial density perturbations and on cosmological parameters ( e.g. , eke _ et al ..
Please generate the next two sentences of the article | _ 1998 ; oukbir & blanchard 1997 ; bahcall , fan & cen 1997 ) . however , most of the important conclusions from such studies are dependent on the accuracy of used scaling relations between the cluster properties , such as the cluster x - ray luminosity , total mass , gas mass , and the electron temperature .
independent of the large scale distribution , baryonic component of the individual clusters has been used to constrain the mass density of the universe , @xmath9 ( e.g. , briel et al . |
8,768 | Suppose that you have an abstract for a scientific paper: i review the current status of understanding the mechanism of the nonmesonic weak decays ( nmwd ) of hypernuclei
. long standing problem on the @xmath0 ratio has been solved by considering short - range weak interactions properly .
this leaves a few remaining problems , such as the asymmetry of the emitted proton with respect to the @xmath1 polarization and validity of the @xmath2 in the nonmesonic weak decay . .
And you have already written the first three sentences of the full article: the year 2003 marks the 50th anniversary of the discovery of hypernucleus . in these 50 years
, the physics of hypernucleus and strange hadrons has played a key role in understanding both the strong and weak interactions of quarks ( and gluons ) .
starting from the eight - fold way , or the flavor su(3 ) symmetry , various symmetries of hadron spectroscopy and interactions , such as current algebra , were born from the strangeness physics . in 1990.
Please generate the next two sentences of the article | s , we have seen a marvelous development both in experimental and theoretical hypernuclear physics . it has accomplished fairly good description of the strong , electromagnetic and weak interactions of hyperons in nuclear medium .
especially a series of new experimental data on the weak decays have lead us to a nearly full understanding of the mechanisms of the weak decays of the hyperon in nuclei . |
8,769 | Suppose that you have an abstract for a scientific paper: in the beginning of the 1950 s , wigner introduced a fundamental deformation from the canonical quantum mechanical harmonic oscillator , which is nowadays sometimes called a wigner quantum oscillator or a parabose oscillator .
also , in quantum mechanics the so - called wigner distribution is considered to be the closest quantum analogue of the classical probability distribution over the phase space . in this article , we consider which definition for such distribution function could be used in the case of non - canonical quantum mechanics .
we then explicitly compute two different expressions for this distribution function for the case of the parabose oscillator .
both expressions turn out to be multiple sums involving ( generalized ) laguerre polynomials .
plots then show that the wigner distribution function for the ground state of the parabose oscillator is similar in behaviour to the wigner distribution function of the first excited state of the canonical quantum oscillator .
* the wigner distribution function for the one - dimensional parabose oscillator * + e. jafarov@xmath0 , s. lievens@xmath1 and j. van der jeugt@xmath2 + @xmath3 department of applied mathematics and computer science , + ghent university , krijgslaan 281-s9 , b-9000 gent , belgium + [email protected] [email protected] , [email protected] + @xmath4 institute of physics , azerbaijan national academy of sciences , + javid avenue 33 , az1143 , baku , azerbaijan + [email protected] + @xmath5 institute of mathematics , statistics and actuarial science + university of kent , cornwallis building , kent ct2 7nf , united kingdom + [email protected] _ keywords : _ wigner distribution function , non - canonical quantum mechanics , phase space , parabose oscillator + _ running head : _ wigner d.f . for the parabose oscillator .
And you have already written the first three sentences of the full article: the harmonic oscillator is one of the most appealing models due to its well known solutions in classical mechanics and in quantum mechanics , and due to a wide variety of applications in various branches of physics @xcite . in classical mechanics
its solution is unique , and so it is in the canonical non - relativistic treatment in quantum mechanics @xcite . in this quantum approach ,
the position and momentum operators ( @xmath6 and @xmath7 , respectively ) satisfy the canonical commutation relation @xmath8 = - i\hbar $ ] , and the model is described by its hamiltonian @xmath9 and the heisenberg equations ..
Please generate the next two sentences of the article | this algebraic description can be translated to a description by means of wave functions . in the position representation , for example
, the operator @xmath7 corresponds to multiplying functions by the variable @xmath10 and the heisenberg operator equations correspond to schrdinger s equation , the solutions of which are expressed through hermite polynomials . |
8,770 | Suppose that you have an abstract for a scientific paper: we analyze intermediate degree _ p_- and _ f_-mode eigenfrequencies measured by gong and mdi / soho for a complete solar cycle to study their correlation with solar activity .
we demonstrate that the frequencies do vary linearly with the activity , however the degree of correlation differs from phase to phase of the cycle . during the rising and the declining phases ,
the mode frequencies are strongly correlated with the activity proxies whereas during the low- and high - activity periods , the frequencies have significantly lower correlation with all the activity proxies considered here . .
And you have already written the first three sentences of the full article: the linear variation of mode frequencies with the changing solar magnetic activity is well established @xcite .
however , detailed studies based on high quality uniform data indicate the complexity of the relationship between mode frequencies and solar activity .
for example , @xcite have shown that there is a latitudinal variation in frequencies and splitting coefficients ..
Please generate the next two sentences of the article | in addition , @xcite found a year - wise distribution in linear - regression slopes ( i e. the change in frequency per unit change in activity ) and the degree of correlation .
thus , with the availability of continuous data for a complete solar cycle , it is important to study correlations of oscillation frequencies with different measures of the solar activity in order to understand the source of the variability . |
8,771 | Suppose that you have an abstract for a scientific paper: metropolis simulations of all - atom models of peptides ( i.e. small proteins ) are considered .
inspired by the funnel picture of bryngelson and wolyness , a transformation of the updating probabilities of the dihedral angles is defined , which uses probability densities from a higher temperature to improve the algorithmic performance at a lower temperature . the method is suitable for canonical as well as for generalized ensemble simulations .
a simple approximation to the full transformation is tested at room temperature for met - enkephalin in vacuum .
integrated autocorrelation times are found to be reduced by factors close to two and a similar improvement due to generalized ensemble methods enters multiplicatively .
address=@xmath0department of physics , florida state university , tallahassee , fl 32306 , usa + @xmath1school of computational science and information technology + florida state university , fl 32306 , usa .
And you have already written the first three sentences of the full article: reliable simulations of biomolecules are one of nowadays grand challenges of computational science . in particular the problem of protein folding thermodynamics starting purely from an aminino - acid sequence has received major attention . until recently the prevailing view has been that it is elusive to search for the native states with present day simulational techniques due to limitations of time scale and force field accuracy .
now a barrier appears to be broken , as it was reported @xcite that large scale distributed computing allows to achieve folding of the 23-residue design mini - protein bba5 , which is relatively insensitive to inaccuracies of the force field .
the relaxation dynamics of the computer simulation is found to be in good agreement with the experimentally observed folding times and equilibrium constants ..
Please generate the next two sentences of the article | molecular dynamics ( md ) technics , for a review see @xcite , tend to be the method of first choice for simulations of biomolecules .
one of the attractive features of md is that it allows to follow the physical time evolution of the system under investigation . |
8,772 | Suppose that you have an abstract for a scientific paper: a family of spherical shells with varying thickness is derived by using a simple newtonian potential - density pair .
then , a particular isotropic form of a metric in spherical coordinates is used to construct a general relativistic version of the newtonian family of shells .
the matter of these relativistic shells presents equal azimuthal and polar pressures , while the radial pressure is a constant times the tangential pressure .
we also make a first study of stability of both the newtonian and relativistic families of shells .
_ keywords _ : gravitation . .
And you have already written the first three sentences of the full article: distributions of matter in form of shells have been a useful tool in astrophysics and general relativity , often providing simplified but analytically tractable models in cosmology , gravitational collapse and supernovae . in general relativity ,
the pioneering work on constructing solutions of the einstein field equations representing shells was done by israel @xcite . in his formalism , the shells are constructed by joining two manifolds across a three - dimensional time - like surface , and the matter representing the shell is interpreted as a discontinuity of the extrinsic curvature on the surface .
this formalism has been used to study several models of relativistic shells . @xcite.
Please generate the next two sentences of the article | give a brief review of some of these models and also discuss shells which admit closed equations of state , including non - linear polytropic models .
an exact solution of a static shell surrounding a black hole was obtained by @xcite , and the stability of such a configuration against radial perturbations was studied by @xcite , while non - radial perturbations were analysed by @xcite . |
8,773 | Suppose that you have an abstract for a scientific paper: starting from a model of 4f - electron generated quadrupolar densities on a compressible fcc lattice , the elastic anomalies at the @xmath0 phase transition are studied by means of analytical theory .
the model is taken as representative for the @xmath1 phase transition in ce .
the coupling of the ( linear ) lattice displacements to the square of the quadrupolar orientational density fluctuations renormalizes the elastic constants .
the condensation of the quadrupolar densities into the orientationally ordered @xmath2 structure is studied as function of temperature and pressure .
precursor effects of the transition lead to an anomalous softening of the elastic constant @xmath3 while @xmath4 exhibits no such softening .
the theoretical results are in excellent qualitative agreement with pressure experiments on the elastic constants ( equivalently on sound velocities ) at the @xmath1 transition in ce .
lattice dynamical analogies in theory and striking similarities in experimental results with the @xmath0 transition in c@xmath5 fullerite are discussed . .
And you have already written the first three sentences of the full article: cerium , the first of the lanthanide series ( rare earths ) with an inner 4f - electron exhibits a broad range of unusual electronic , magnetic and structural properties in the solid state @xcite .
most intriguing is the transformation under pressure @xcite between two face - centered - cubic ( fcc ) phases called @xmath6-ce and @xmath7-ce . while @xmath6-ce is stable at room temperature ( @xmath8 ) and ambient pressure ( @xmath9 ) , it transforms to @xmath7-ce at @xmath10 gpa .
this apparent isostructural phase transition @xmath11 is accompanied by a @xmath1215% volume reduction and a change in magnetism . while in the @xmath6-phase the magnetic susceptibility @xmath13 follows a curie weiss law which is attributed to the magnetic moment of the 4f - electron , it is a quasi @xmath8-independent in the @xmath7-phase and reminiscent of pauli paramagnetism @xcite ..
Please generate the next two sentences of the article | the isostructural nature of the @xmath11 transition is at variance with the landau theory of phase transitions @xcite which would require a change of space group symmetry . since the establishing of the fcc structure for both phases @xcite various microscopic theories have been proposed . nowadays
two theoretical models are well represented in the literature . |
8,774 | Suppose that you have an abstract for a scientific paper: we show that for a heavy vector - like quark model with a down type isosinglet , branching ratio for @xmath0 decay is enhanced by more than @xmath1 as compared to that in the standard model when qcd corrections to next - to - leading order are incorporated . in a left - right symmetric model ( lrsm ) along with a heavy vector - like fermion , enhancement of this order can be achieved at the bare ( qcd uncorrected ) level itself .
we propose that a measurement of the photon polarization could be used to signal the presence of such new physics inspite of the large long distance effects .
we find that there is a large region within the allowed parameter space of the lrsm , as well as in the model with vector - like quark with additional left - right symmetry , where the photon polarization can be dominantly right - handed . .
And you have already written the first three sentences of the full article: the direct search for physics beyond the standard model(sm ) has been unsuccessful thus far .
there have been anomalies in some of the observables in the flavour sector , with deviations from the sm predictions at the level of few sigma @xcite .
in fact , the presence of new physics(np ) at possibly high scales may very well be deduced only from precision measurements of some of the rare meson decays ..
Please generate the next two sentences of the article | the absence of flavour changing neutral currents ( fcncs ) at the tree level allows the possibility of virtual new physics particles to be present in the loop level diagrams that contribute to these processes .
detailed study of rare charm decays was performed in ref . |
8,775 | Suppose that you have an abstract for a scientific paper: we study the kondo effect of a quantum dot placed in a complex mesoscopic structure . assuming that electronic interactions are taking place solely on the dot , and focusing on the infinite hubbard interaction limit , we use a decoupling scheme to obtain an explicit analytic approximate expression for the dot green function , which fulfills certain fermi - liquid relations at zero temperature .
the details of the complex structure enter into this expression only via the self - energy for the non - interacting case .
the effectiveness of the expression is demonstrated for the single impurity anderson model and for the t - shaped network . 2 .
And you have already written the first three sentences of the full article: the single - impurity anderson model ( siam ) has been a paradigm of a strongly correlated electron system .
@xcite this seemingly simple model gives rise to dynamical screening of the local spin by the electrons in the fermi sea , leading to a crossover from a weak coupling system at high temperatures ( @xmath0 ) to a strongly coupled one at low @xmath0 , with the relevant temperature scale given by the kondo temperature , @xmath1 .
the recent observation of the kondo effect in quantum dots ( qd s ) , whose parameters can be tuned continuously , and which allow probing of various properties , @xcite has yielded strong theoretical efforts in this direction ..
Please generate the next two sentences of the article | @xcite recent experiments on a qd embedded on one branch of the aharonov - bohm interferometer @xcite created additional interest in kondo effects in _
complex networks_. while the high-@xmath0 behavior of the siam can be adequately described by perturbation theory or poor - man scaling , @xcite and the low-@xmath0 behavior is described by fermi liquid theory , @xcite there is no _ simple _ theory that describes the model s dynamical properties correctly in the whole temperature range , including _ both _ the high- and the low-@xmath0 limits . |
8,776 | Suppose that you have an abstract for a scientific paper: a number of calculations have appeared for the bose - einstein condensation temperature ( @xmath0 ) of a weakly repulsive dilute bose gas . after a short survey of previous work ,
i point out several issues related to these approaches , and outline future calculations . .
And you have already written the first three sentences of the full article: during the recent upsurge of activity in the field of bose - einstein condensation ( bec ) , some older questions concerning the weakly interacting bose gas have been revived .
one such un - resolved question is the effect of a weak repulsion on the critical temperature @xmath0 .
calculations on this question has produced widely dissimilar results : increases and decreases of @xmath0 proportional to @xmath1 , @xmath2 , @xmath3 , etc ..
Please generate the next two sentences of the article | have been reported by various authors .
( here @xmath1 is the scattering length . ) |
8,777 | Suppose that you have an abstract for a scientific paper: the very short and bright flare of 3c 279 detected with _ fermi_-lat in 2013 december is tested by a model with stochastic electron acceleration by turbulences .
our time - dependent simulation shows that the very hard spectrum and asymmetric light curve are successfully reproduced by changing only the magnetic field from the value in the steady period .
the maximum energy of electrons drastically grows with the decrease of the magnetic field , which yields a hard photon spectrum as observed .
rapid cooling due to the inverse - compton scattering with the external photons reproduces the decaying feature of the light curve .
the inferred energy density of the magnetic field is much less than the electron and photon energy densities .
the low magnetic field and short variability timescale are unfavorable for the jet acceleration model from the gradual poynting flux dissipation . .
And you have already written the first three sentences of the full article: multi - wavelength light curves of blazar flares show complex and diversified features . while in some cases there is a time lag between gamma - ray and x - ray / optical flares ( e.g. * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ) , in other cases an orphan flare in a certain wavelength was detected ( e.g. * ? ? ? |
8,778 | Suppose that you have an abstract for a scientific paper: we study a chaotic ratchet system under the influence of a thermal environment . by direct integration of the lindblad equation
we are able to analyze its behavior for a wide range of couplings with the environment , and for different finite temperatures .
we observe that the enhancement of the classical and quantum currents due to temperature depend strongly on the specific properties of the system .
this makes difficult to extract universal behaviors .
we have also found that there is an analogy between the effects of the classical thermal noise and those of the finite @xmath0 size .
these results open many possibilities for their testing and implementation in kicked becs and cold atoms experiments . .
And you have already written the first three sentences of the full article: the first theoretical constructions related with directed transport have been formulated in an early work by feynman @xcite .
this opened a field whose relevance and activity has been increasing since then .
the motivation is twofold , in the first place several fundamental questions have originated from these ideas and have been only partially answered @xcite . as a consequence ,.
Please generate the next two sentences of the article | the subject grew into a major new field of statistical physics . on the other hand ,
the wealth of possible applications has determined the emergence of a very broad area of research in physics . |
8,779 | Suppose that you have an abstract for a scientific paper: we study the decays of top squarks ( @xmath0 ) and bottom squarks ( @xmath1 ) in the minimal supersymmetric standard model ( mssm ) with complex parameters @xmath2 and @xmath3 .
we show that including the corresponding phases strongly affects the branching ratios of @xmath0 and @xmath1 decays in a large domain of the mssm parameter space .
this could have an important impact on the search for @xmath4 and @xmath5 and the determination of the underlying mssm parameters at future colliders .
tgu-34 + uwthph-2004 - 26 + hep - ph/0409347 + a. bartl@xmath6 , s. hesselbach@xmath6 , @xmath7 , t. kernreiter@xmath6 and w. porod@xmath8 [ cols= " < " , ] .
And you have already written the first three sentences of the full article: many phenomenological studies on susy particle searches have been performed in the minimal supersymmetric standard model ( mssm ) with real susy parameters . in general , however , some of the susy parameters may be complex , in particular the higgsino mass parameter @xmath9 , the gaugino mass parameters @xmath10 and the trilinear scalar coupling parameters @xmath11 of the sfermions @xmath12 .
the su(2 ) gaugino mass parameter @xmath13 can be chosen real after an appropriate redefinition of the fields .
not only the cp - violating observables ( such as fermion edms ) but also the cp - conserving observables ( such as cross sections and decay branching ratios ) depend on the phases of the complex parameters , because in general the mass - eigenvalues and the couplings of the susy particles involved are functions of the underlying complex parameters ..
Please generate the next two sentences of the article | for example , the decay branching ratios of the staus @xmath14 and @xmath15-sneutrino @xmath16 can be quite sensitive to the complex phases of the stau and gaugino - higgsino sectors @xcite .
therefore , in a complete phenomenological analysis of production and decays of the susy particles one has to take into account that @xmath11 , @xmath9 and @xmath17 can be complex . in this article based on @xcite |
8,780 | Suppose that you have an abstract for a scientific paper: combining thermodynamic measurements with theoretical density functional and thermodynamic calculations we demonstrate that the honeycomb lattice iridates @xmath0iro@xmath1 ( @xmath2na , li ) are magnetically ordered mott insulators where the magnetism of the effective spin - orbital s=1/2 moments can be captured by a heisenberg - kitaev ( hk ) model with heisenberg interactions beyond nearest - neighbor exchange .
experimentally , we observe an increase of the curie - weiss temperature from @xmath3 k for na@xmath4iro@xmath1 to @xmath5 k for li@xmath4iro@xmath1 , while the antiferromagnetic ordering temperature remains roughly the same @xmath6 k for both materials .
using finite - temperature functional renormalization group calculations we show that this evolution of @xmath7 , @xmath8 , the frustration parameter @xmath9 , and the zig - zag magnetic ordering structure suggested for both materials by density functional theory can be captured within this extended hk model . combining our experimental and theoretical results
, we estimate that na@xmath4iro@xmath1 is deep in the magnetically ordered regime of the hk model ( @xmath10 ) , while li@xmath4iro@xmath1 appears to be close to a spin - liquid regime ( @xmath11 ) .
[ [ introduction . ] ] introduction. + + + + + + + + + + + + + + the fundamental importance of the kitaev model , which describes the highly anisotropic exchange of su(2 ) spin-1/2 moments on the honeycomb lattice , has quickly been appreciated for its rare combination of microscopic simplicity and an exact analytical solution @xcite .
it has also become an archetypal example of a microscopic model that
depending on the spatial anisotropy of its couplings harbors three of the currently most sought - after collective states in condensed matter physics @xcite : a gapless spin liquid with emergent majorana fermion excitations , a gapped @xmath12 spin liquid , and a topologically ordered phase with non - abelian quasiparticle statistics ( in the presence of a magnetic field....
And you have already written the first three sentences of the full article: [ [ synthesis . ] ] synthesis. + + + + + + + + + + + polycrystalline samples of @xmath0iro@xmath1 ( @xmath2 na , li ) and li@xmath4sno@xmath1 were synthesized by solid state synthesis .
high purity starting materials @xmath0co@xmath1 ( @xmath2 na , li ) ( 99.995% alfa aesar ) and ir metal powder ( @xmath98 alfa aesar ) or sno@xmath4 ( 99.995% alfa aesar ) were mixed in the ratio 1.05 : 1 and placed in an alumina crucible with a lid and given heat treatments between 750 @xmath99c and 950 @xmath99c in steps of 50 @xmath99c with intermediate grindings and pelletizing after each step .
the li@xmath4sno@xmath1 sample was given a further heat treatment at 1000 @xmath99c . in an attempt to grow single crystals.
Please generate the next two sentences of the article | the li@xmath4iro@xmath1 sample was dissolved in excess licl flux at 850 @xmath99c for 6 hrs and then cooled to 590 @xmath99c at 3 @xmath99c / hr . after washing majority of the licl flux with de - ionized water we obtained a fine black powder which turned out to be highly ordered li@xmath4iro@xmath1 polycrystalline samples .
this powder was pelletized and sin tered at 900 @xmath99c for 48 hrs to get a hard pellet for resistivity and heat capacity measurements . |
8,781 | Suppose that you have an abstract for a scientific paper: we investigate the nonlinear interaction between a relativistically strong laser beam and a plasma in the quantum regime .
the collective behavior of the electrons is modeled by a klein - gordon equation , which is nonlinearly coupled with the electromagnetic wave through the maxwell and poisson equations .
this allows us to study the nonlinear interaction between arbitrarily large amplitude electromagnetic waves and a quantum plasma .
we have used our system of nonlinear equations to study theoretically the parametric instabilities involving stimulated raman scattering and modulational instabilities .
a model for quasi - steady state propagating electromagnetic wavepackets is also derived , and which shows the possibility of localized solitary structures in the quantum plasma .
numerical simulations demonstrate the collapse and acceleration of the electrons in the nonlinear stage of the modulational instability , as well as the possibility of wake - field acceleration of the electrons to relativistic speeds by short laser pulses at nanometer length scales .
the study has importance for the nonlinear interaction between a super - intense x - ray laser light and a solid - density plasma , where quantum effects are important . .
And you have already written the first three sentences of the full article: with the advent of the x - ray free - electron lasers @xcite there are new possibilities to explore matter on atomic and single molecule levels . on these length scales , of the order of a few ngstrm , quantum effects play an important role in the dynamics of the electrons .
quantum effects have been measured experimentally both in the degenerate electron gas in metals and in warm dense matters @xcite .
it has also been found that quantum mechanical effects must be taken into account in intense laser - solid density plasma interaction experiments @xcite ..
Please generate the next two sentences of the article | the interaction of large amplitude electromagnetic waves with the plasma can lead to various parametric instabilities @xcite . at laser intensities around @xmath0 and above
, the nonlinearity associated with relativistic electron mass increase in short laser pulses plays a significant role . |
8,782 | Suppose that you have an abstract for a scientific paper: consider the construction of an object composed of @xmath0 parts by distributing @xmath1 units to those parts .
for example , say we are assigning @xmath1 balls to @xmath0 boxes .
each assignment results in a certain count vector , specifying the number of balls allocated to each box .
if only assignments satisfying a set of constraints that are linear in these counts are allowable , and @xmath0 is fixed while @xmath1 increases , most assignments that satisfy the constraints result in frequency vectors ( normalized counts ) whose entropy approaches that of the maximum entropy vector satisfying the constraints . this phenomenon of `` entropy concentration '' is known in various forms , and is one of the justifications of the maximum entropy method , one of the most powerful tools for solving problems with incomplete information .
the appeal of entropy concentration comes from the simplicity of the argument : it is based purely on counting and does not need probabilities .
existing proofs of the concentration phenomenon are based on limits or asymptotics . here
we present non - asymptotic , explicit lower bounds on @xmath1 for a number of variants of the concentration result to hold to any prescribed accuracies , taking into account the fact that allocations of discrete units can satisfy constraints only approximately .
the results are illustrated with examples on die tossing , vehicle or network traffic , and the probability distribution of the length of a @xmath2 queue . .
And you have already written the first three sentences of the full article: consider a process which is repeated @xmath1 times and each repetition has @xmath0 possible outcomes . for concreteness we may think of assigning @xmath1 balls to @xmath0 labelled boxes , where each box can hold any number of balls .
the first ball can go into any box , the second ball can go into any box , ... , and the @xmath1th ball can go into any box .
each assignment or allocation is thus a sequence of @xmath1 box labels and results in some number @xmath3 of balls in box 1 , @xmath4 in box 2 , etc . , where the @xmath5 are @xmath6 and sum to @xmath1.
Please generate the next two sentences of the article | . there are @xmath7 possible assignments in all , and many of them can lead to the same count vector @xmath8 .
we refer to these assignments as the _ realizations _ of the count vector . |
8,783 | Suppose that you have an abstract for a scientific paper: we present a homogeneous catalogue for blue straggler , red giant branch , horizontal branch and main - sequence turn - off stars in a sample of 35 clusters taken from the acs survey for globular clusters . as a result of the superior photometry and relatively large field of view offered by the acs data ,
this new catalogue is a significant improvement upon the one presented in @xcite . using our catalogue ,
we study and compare the radial distributions of the different stellar populations .
we have confirmed our previous result @xcite that there is a clear , but sub - linear , correlation between the number of blue stragglers found in the cluster core and the total stellar mass contained within it . by considering a larger spatial extent than just the core
, our results suggest that mass segregation is not the dominant effect contributing to the observed sub - linearity .
we also investigate the radial distributions of the different stellar populations in our sample of clusters .
our results are consistent with a linear relationship between the number of stars in these populations and the total mass enclosed within the same radius .
therefore , we conclude that the cluster dynamics does not significantly affect the relative distributions of these populations in our sample .
[ firstpage ] stars : blue stragglers globular clusters : general stellar dynamics stars : statistics catalogues . .
And you have already written the first three sentences of the full article: colour - magnitude diagrams ( cmds ) are one of the most important tools available to astronomers for studying stellar evolution , stellar populations and star clusters . and yet , there remain several features found in cmds whose origins are still a mystery .
examples include horizontal branch ( hb ) morphology , the presence of extended horizontal branch ( ehb ) stars , and blue stragglers ( bss ) ( e.g. * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ; * ? ? ? |
8,784 | Suppose that you have an abstract for a scientific paper: we study a class of @xmath0 supergravity inflationary models in which the evolution of the inflaton dynamics is controlled by a single power in the inflaton field at the point where the observed density fluctuations are produced , in the context of the braneworld scenario , in light of wmap results .
in particular , we find that the bounds on the spectral index and its running constrain the parameter space both for models where the inflationary potential is dominated by a quadratic term and by a cubic term in the inflaton field .
we also find that @xmath1 is required for the quadratic model whereas @xmath2 for the cubic model .
moreover , we have determined an upper bound on the five - dimensional planck scale , @xmath3 m , for the quadratic model . on the other hand , a running spectral index with @xmath4 on large scales and @xmath5 on small scales
is not possible in either case
. 0.5 cm 0.5 cm .
And you have already written the first three sentences of the full article: the first year wmap data has confirmed the `` concordance '' values of the cosmological parameters with unprecedented accuracy and given important information on the primordial spectrum of density perturbations @xcite .
their results favor gaussian , purely adiabatic fluctuations and a spectral index that runs from @xmath4 on large scales to @xmath5 on small scales .
moreover , wmap has confirmed earlier cobe dmr observations that there is a lower amount of power on the largest scales when compared to that predicted by the standard @xmath6cdm models . although these results are not yet firmly established ( for an analysis of wmap results which finds no evidence of running see ref ..
Please generate the next two sentences of the article | @xcite ) , it seems worthwhile to reexamine inflationary models in light of wmap results , as they may give us further insight into the very early universe .
supergravity inflationary models are particularly important as supersymmetry ( or its local version , supergravity ) is the only known way to avoid the hierachy problem , i.e. the fact that the high energy scale of inflation communicates to other sectors of the theory driving the electroweak scale much above its observed value via radiative corrections . |
8,785 | Suppose that you have an abstract for a scientific paper: chtelet surfaces provide a rich source of geometrically rational surfaces which do not always satisfy the hasse principle .
we investigate the frequency that such counter - examples arise over the rationals . .
And you have already written the first three sentences of the full article: a family of geometrically integral algebraic varieties defined over @xmath0 is said to satisfy the hasse principle if any variety in the family has a point in @xmath0 as soon as it has points in every completion of @xmath0 .
quadrics are among the first examples of families satisfying this property . in dimension
@xmath1 , chtelet surfaces constitute a family of varieties for which the hasse principle is known to fail in general ..
Please generate the next two sentences of the article | the chtelet surfaces that we consider are proper smooth models of affine surfaces @xmath2 where @xmath3 $ ] is a separable polynomial of degree @xmath4 or @xmath5 . for these surfaces it follows from work of colliot - thlne , sansuc and swinnerton - dyer @xcite that all failures of the hasse principle are accounted for by the brauer manin obstruction , a cohomological obstruction based on the brauer group of the surface .
in particular it is known that the hasse principle holds whenever @xmath6 is irreducible over @xmath0 , which is the generic situation , or when @xmath6 has a linear factor over @xmath0 . in the remaining case , |
8,786 | Suppose that you have an abstract for a scientific paper: the temperature induced phase transition is investigated in the one - component scalar field @xmath0 model on a lattice by using monte carlo simulations . using the gpgpu technology a huge amount of data
is collected that gives a possibility to determine the linde - weinberg low bound on the coupling constant @xmath1 and investigate the type of the phase transition for a wide interval of coupling values .
it is found that for the values of @xmath2 close to this bound a weak - first - order phase transition happens .
it converts into a second order phase transition with the increase of @xmath2 .
a comparison with analytic calculations in continuum field theory and lattice simulations obtained by other authors is given .
_ keywords : _ scalar model ; phase transitions ; gpu .
And you have already written the first three sentences of the full article: the temperature induced phase transition in the @xmath3 scalar field model with a spontaneous symmetry breaking ( ssb ) has a long history of investigations .
it was studied either by analytic methods of the quantum field theory or in lattice simulations ( see refs.@xcite and references therein ) .
it was recently observed by analytic calculations within the perturbation theory ( pt ) in the daisy , super daisy and some type beyond resummations @xcite that a phase transition of the first order could occur in the @xmath4-model ..
Please generate the next two sentences of the article | however , the lack of the expansion parameter happens near the phase transition temperature @xmath5 for various kind resummations .
so , it is impossible to draw a reliable conclusion about the transition type even for small values of the coupling constant @xmath2 . in ref.@xcite |
8,787 | Suppose that you have an abstract for a scientific paper: we study the stability / instability of the subsonic travelling waves of the nonlinear schrdinger equation in dimension one .
our aim is to propose several methods for showing instability ( use of the grillakis - shatah - strauss theory , proof of existence of an unstable eigenvalue via an evans function ) or stability .
for the later , we show how to construct in a systematic way a liapounov functional for which the travelling wave is a local minimizer .
these approaches allow to give a complete stability / instability analysis in the energy space including the critical case of the kink solution .
we also treat the case of a cusp in the energy - momentum diagram .
+ * key - words : * travelling wave , nonlinear schrdinger equation , gross - pitaevskii equation , stability , evans function , liapounov functional . + *
msc ( 2010 ) : * 35b35 , 35c07 , 35j20 , 35q40 , 35q55 . .
And you have already written the first three sentences of the full article: this paper is a continuation of our previous work @xcite , where we consider the one dimensional nonlinear schrdinger equation i + _
x^2 + f(||^2 ) = 0 .
this equation appears as a relevant model in condensed matter physics : bose - einstein condensation and superfluidity ( see @xcite , @xcite , @xcite , @xcite ) ; nonlinear optics ( see , for instance , the survey @xcite ) ..
Please generate the next two sentences of the article | several nonlinearities may be encountered in physical situations : @xmath0 gives rise to the focusing / defocusing cubic ( nls ) ; @xmath1 to the so called gross - pitaevskii equation ; @xmath2 ( see @xcite for bose - einstein condensates ) ; more generally a pure power ; the `` cubic - quintic '' ( nls ) ( see @xcite ) , where @xmath3 and @xmath4 , @xmath5 and @xmath6 are positive constants such that @xmath7 has two positive roots ; and in nonlinear optics , we may take ( see @xcite ) : [ nonlin ] f ( ) = - ^- ^2 , f ( ) = - ( - ) , f ( ) = - ( 1 + tanh ( ) ) , where @xmath8 , @xmath9 , @xmath10 , @xmath11 , @xmath12 are given constants ( the second one , for instance , takes into account saturation effects ) , etc . as a consequence , as in our work @xcite , we shall consider a rather general nonlinearity @xmath13 , with @xmath13 of class @xmath14 . in the context of bose - einstein condensation or nonlinear optics ,
the natural condition at infinity appears to be @xmath15 where @xmath16 is such that @xmath17 . |
8,788 | Suppose that you have an abstract for a scientific paper: crane and frenkel proposed a state sum invariant for triangulated 4-manifolds .
they defined and used new algebraic structures called hopf categories for their construction .
crane and yetter studied hopf categories and gave some examples using group cocycles that are associated to the drinfeld double of a finite group . in this paper
we define a state sum invariant of triangulated @xmath0-manifolds using crane - yetter cocycles as boltzmann weights .
our invariant generalizes the 3-dimensional invariants defined by dijkgraaf and witten and the invariants that are defined via hopf algebras .
we present diagrammatic methods for the study of such invariants that illustrate connections between hopf categories and moves to triangulations .
[ section ] [ sect ] .
And you have already written the first three sentences of the full article: witten s formulation @xcite of an intrinsic definition of the jones polynomial @xcite based on physical models lead to the more rigorous mathematical definitions via representations of quantum groups that were given by reshetikhin , turaev , and viro @xcite , @xcite .
these quantum invariants are speculated to generalize to higher dimensions .
such putative invariants have their origins in a theory of quantum gravity @xcite and higher categories @xcite . in relation to the current work.
Please generate the next two sentences of the article | , the following progress has been made .
quantum spin networks were generalized by crane - yetter @xcite to give @xmath0-manifold invariants that were based on ooguri s proposal @xcite . |
8,789 | Suppose that you have an abstract for a scientific paper: using various relativistic mean - field models , including the nonlinear ones with meson field self - interactions , those with density - dependent meson - nucleon couplings , and the point - coupling models without meson fields , we have studied the isospin - dependent bulk and single - particle properties of asymmetric nuclear matter . in particular , we have determined the density dependence of nuclear symmetry energy from these different relativistic mean - field models and compare the results with the constraints recently extracted from analyses of experimental data on isospin diffusion and isotopic scaling in intermediate - energy heavy ion collisions as well as from measured isotopic dependence of the giant monopole resonances in even - a sn isotopes . among the @xmath0 parameter sets in the relativistic mean - filed model that are commonly used for nuclear structure studies , only a few
are found to give symmetry energies that are consistent with the empirical constraints .
we have also studied the nuclear symmetry potential and the isospin - splitting of the nucleon effective mass in isospin asymmetric nuclear matter .
we find that both the momentum dependence of the nuclear symmetry potential at fixed baryon density and the isospin - splitting of the nucleon effective mass in neutron - rich nuclear matter depend not only on the nuclear interactions but also on the definition of the nucleon optical potential . .
And you have already written the first three sentences of the full article: besides the many existing radioactive beam facilities and their upgrades , many more are being constructed or under planning , including the cooling storage ring ( csr ) facility at hirfl in china @xcite , the radioactive ion beam ( rib ) factory at riken in japan @xcite , the fair / gsi in germany @xcite , spiral2/ganil in france @xcite , and the facility for rare isotope beams ( frib ) in the usa @xcite .
these new facilities offer the possibility to study the properties of nuclear matter or nuclei under the extreme condition of large isospin asymmetry . as a result ,
the study of the isospin degree of freedom in nuclear physics has recently attracted much attention ..
Please generate the next two sentences of the article | the ultimate goal of such study is to extract information on the isospin dependence of in - medium nuclear effective interactions as well as the equation of state ( eos ) of isospin asymmetric nuclear matter , particularly its isospin - dependent term or the density dependence of the nuclear symmetry energy .
this knowledge , especially the latter , is important for understanding not only the structure of radioactive nuclei , the reaction dynamics induced by rare isotopes , and the liquid - gas phase transition in asymmetric nuclear matter , but also many critical issues in astrophysics @xcite . |
8,790 | Suppose that you have an abstract for a scientific paper: we consider a reaction - diffusion equation in narrow random channels .
we approximate the generalized solution to this equation by the corresponding one on a random graph .
by making use of large deviation analysis we study the asymptotic wave front propagation .
_ keywords _ : reaction - diffusion equation , wave front propagation , diffusion processes on graphs , random environment .
_ 2010 mathematics subject classification numbers _ : 35k57 , 35a18 , 60j60 , 60k37 . .
And you have already written the first three sentences of the full article: in studying the motion of molecular motors we introduced in @xcite a solvable model : we think of the molecular motors as diffusion particles traveling in a narrow random channel . based on the model suggested in @xcite , we consider in this paper wave front propagation for a reaction - diffusion in narrow random channels .
problems of this type naturally appear in the theory of nerve impulse propagation and in combustion theory .
our analysis relies on techniques in large deviations similar to that of ( * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ; * ? ? ? |
8,791 | Suppose that you have an abstract for a scientific paper: observable effects due to trembling motion ( zitterbewegung , zb ) of charge carriers in bilayer graphene , monolayer graphene and carbon nanotubes are calculated .
it is shown that , when the charge carriers are prepared in the form of gaussian wave packets , the zb has a transient character with the decay time of femtoseconds in graphene and picoseconds in nanotubes .
analytical results for bilayer graphene allow us to investigate phenomena which accompany the trembling motion .
in particular , it is shown that the transient character of zb in graphene is due to the fact that wave subpackets related to positive and negative electron energies move in opposite directions , so their overlap diminishes with time .
this behavior is analogous to that of the wave packets representing relativistic electrons in a vacuum . .
And you have already written the first three sentences of the full article: the trembling motion ( zitterbewegung , zb ) , first devised by schroedinger for free relativistic electrons in a vacuum @xcite , has become in the last two years subject of great theoretical interest as it has turned out that this phenomenon should occur in many situations in semiconductors @xcite .
whenever one deals with two or more energy branches , an interference of the corresponding upper and lower energy states results in the trembling motion even in the absence of external fields . due to a formal similarity between two interacting bands in a solid and the dirac equation for relativistic electron in a vacuum one can use methods developed in the relativistic quantum mechanics for non - relativistic electrons in solids @xcite .
most of the zb studies for semiconductors took as a starting point plane electron waves ( see , however , refs ..
Please generate the next two sentences of the article | @xcite ) . on the other hand
, lock @xcite in his important paper observed : such a wave is not localized and it seems to be of a limited practicality to speak of rapid fluctuations in the average position of a wave of infinite extent. using the dirac equation lock showed that , when an electron is represented by a wave packet , the zb oscillations do not remain undamped but become transient . |
8,792 | Suppose that you have an abstract for a scientific paper: we present linear spectropolarimetric data for eight herbig be and four herbig ae stars at h@xmath0 , h@xmath1 and h@xmath2 .
changes in the linear polarisation are detected across all balmer lines for a large fraction of the observed objects , confirming that the small - scale regions surrounding these objects are flattened ( i.e. disk - like ) .
furthermore , all objects with detections show similar characteristics at the three spectral lines , despite differences in transition probability and optical depth going from h@xmath0 to h@xmath2 . a large fraction of early herbig
be stars ( b0-b3 ) observed show line depolarisation effects .
however the early herbig ae stars ( a0-a2 ) , observed for comparison , show intrinsic line polarisation signatures .
our data suggest that the popular magnetic accretion scenario for t tauri objects may be extended to herbig ae stars , but that it may not be extended to early herbig be stars , for which the available data are consistent with disc accretion .
[ firstpage ] techniques : spectropolarimetry - circumstellar matter - stars : emission - line , herbig , be - stars : formation - stars : pre - main - sequence .
And you have already written the first three sentences of the full article: while magnetic t - tauri type models for low - mass star formation have been reasonably well accepted , there is currently no such picture for the early evolutionary phases of higher mass stars .
many questions , such as whether higher mass stars form via disc accretion , and issues relating to the importance of magnetic fields during high - mass star formation , remain open .
herbig ae / be stars are of considerable interest in attempts to resolve these questions , as they are young stars of intermediate mass ( 2 - 15m@xmath3 ) at the interface between low and high - mass star formation ..
Please generate the next two sentences of the article | in addition , herbig ae / be stars are the most massive stars with a visible pre - main sequence phase .
t tauri stars have relatively strong magnetic fields @xcite and these fields have important physical effects on the accretion flow . |
8,793 | Suppose that you have an abstract for a scientific paper: a _ long unichord _ in a graph is an edge that is the unique chord of some cycle of length at least 5 .
a graph is _ long - unichord - free _ if it does not contain any long - unichord .
we prove a structure theorem for long - unichord - free graph .
we give an @xmath0-time algorithm to recognize them .
we show that any long - unichord - free graph @xmath1 can be colored with at most @xmath2 colors , where @xmath3 is the maximum number of pairwise adjacent vertices in @xmath1 .
* key words : * amalgam , @xmath4-bounded , chords .
* ams classification : * 05c75 , 05c15 , 05c85 . .
And you have already written the first three sentences of the full article: in this article , all graphs are finite and simple .
we denote by @xmath5 the _ chromatic number _ of a graph @xmath1 , that is the minimum number of colors needed to give a color to each vertex in such a way that any two adjacent vertices receive different colors .
we denote by @xmath6 the maximum size of a set of pairwise adjacent vertices ( that we call a _ clique _ ) ..
Please generate the next two sentences of the article | it is clear that for every graph , @xmath7 , while the converse inequality is false in general ( the smallest example is the chordless cycle on five vertices ) .
let @xmath8 be any function from @xmath9 to @xmath9 . |
8,794 | Suppose that you have an abstract for a scientific paper: the current status of neutrino cosmology is reviewed , from the question of neutrino decoupling and the presence of sterile neutrinos to the effects of neutrinos on the cosmic microwave background and large scale structure .
particular emphasis is put on cosmological neutrino mass measurements . .
And you have already written the first three sentences of the full article: next to photons neutrinos are the most abundant particles in the universe .
this means they have a profound impact on many different aspects of cosmology , from the question of leptogenesis in the very early universe , over big bang nucleosynthesis , to late time structure formation . in the present review
i focus mainly on late - time aspects of neutrino cosmology , and particularly on issues relevant to cosmological bounds on the neutrino mass ..
Please generate the next two sentences of the article | the absolute value of neutrino masses are very difficult to measure experimentally . on the other hand , mass differences between neutrino mass eigenstates , @xmath0 ,
can be measured in neutrino oscillation experiments . |
8,795 | Suppose that you have an abstract for a scientific paper: in this paper we present a new approach to control variates for improving computational efficiency of ensemble monte carlo .
we present the approach using simulation of paths of a time - dependent nonlinear stochastic equation .
the core idea is to extract information at one or more nominal model parameters and use this information to gain estimation efficiency at neighboring parameters .
this idea is the basis of a general strategy , called database monte carlo ( dbmc ) , for improving efficiency of monte carlo . in this paper
we describe how this strategy can be implemented using the variance reduction technique of control variates ( cv ) .
we show that , once an initial setup cost for extracting information is incurred , this approach can lead to significant gains in computational efficiency .
the initial setup cost is justified in projects that require a large number of estimations or in those that are to be performed under real - time constraints .
monte carlo , variance reduction , control variates s05.10.ln , 02.70.uu , 02.70.tt .
And you have already written the first three sentences of the full article: the purpose of this paper is to present a novel approach for efficient estimation via the monte carlo ( mc ) method .
the approach is very broadly applicable but here , to present the main ideas , we narrow the focus to ensemble monte carlo where estimation is based on stochastically independent trajectories of a system . to illustrate , we use simulation of time - dependent nonlinear processes
for which monte carlo is a particularly general and powerful numerical method compared to available alternatives ..
Please generate the next two sentences of the article | time - dependent nonlinear processes are very general models used , among others , in statistical mechanics @xcite , data assimilation in climate , weather and ocean modeling @xcite , financial modeling @xcite , and quantitative biology @xcite . hence developing efficient mc methods
may significantly impact a wide range of applications . |
8,796 | Suppose that you have an abstract for a scientific paper: we investigate the intrinsic abundance ratio of @xmath0co to c@xmath1o and the x - factor in l1551 using the nobeyama radio observatory ( nro ) 45 m telescope .
l1551 is chosen because it is relatively isolated in the taurus molecular cloud shielded from fuv photons , providing an ideal environment for studying the target properties .
our observations cover @xmath240@xmath340with resolution @xmath230 , which are the maps with highest spatial dynamical range to date .
we derive the @xmath4 value on the sub - parsec scales in the range of @xmath2327 with a mean value of [email protected] . comparing to the visual extinction map derived from the @xmath6 observations
, we found that the abundance ratio reaches its maximum at low @xmath7 ( i.e. , @xmath8 14mag ) , and decreases to the typical solar system value of 5.5 inside l1551 mc . the high @xmath4 value at the boundary of the cloud is most likely due to the selective fuv photodissociation of c@xmath1o .
this is in contrast with orion - a where its internal ob stars keep the abundance ratio at a high level greater than @xmath210 . in addition
, we explore the variation of the x - factor , because it is an uncertain but widely used quantity in extragalactic studies .
we found that x - factor @xmath9 @xmath10 which is consistent with previous simulations . excluding the high density region ,
the average x - factor is similar to the milky way average value . .
And you have already written the first three sentences of the full article: the ultraviolet ( uv ) radiation plays a crucial role in many processes of the interstellar medium ( ism ) , such as photoelectric heating , grain charging , photoionization , and photo - dissociation of molecules @xcite , in which the far - ultraviolet ( fuv : 6ev @xmath11 13.6ev ) radiation from massive stars or interstellar radiation field ( isrf ) influences the structure , chemistry , thermal balance , and evolution of neutral interstellar medium @xcite .
therefore , studying these influence helps to understand the process of star formation .
the fuv emission selectively dissociates co rare isotopologues more effectively than co owing to different levels of self - shielding effects @xcite . for the fuv emission with energy high enough to photodissociate @xmath12co , it rapidly becomes optically thick when it penetrates into molecular clouds ..
Please generate the next two sentences of the article | in contrast , the self - shielding effect of c@xmath1o is relatively less significant because of the shift of its absorption lines and its low abundance .
therefore , the fuv emission with energy above the c@xmath1o dissociation level is expected to penetrate relatively deeper in a molecular cloud , and the abundance ratio of @xmath0co and c@xmath1o , @xmath4 , will increase when the self - shielding effect of c@xmath1o does not yet dominate . when the self - shielding effect of both @xmath0co and c@xmath1o become important , the abundance ratio should decrease toward the intrinsic abundance value which derived from abundances of the elements , @xmath12c , @xmath0c , @xmath13o , and @xmath1c . the intrinsic value may vary as the distance to the galactic center @xcite . |
8,797 | Suppose that you have an abstract for a scientific paper: in a recent series of three papers , belokurov , evans , & le du ( 2002 , 2004 ) , and evans & belokurov ( 2004 ) , reanalysed the macho collaboration data and gave alternative sets of microlensing events and an alternative optical depth to microlensing toward the large magellanic cloud ( lmc ) . even though they examined less than 0.2% of the data they claimed that by using a neural net program they had reliably selected a better ( and smaller ) set of microlensing candidates . estimating the optical depth from this smaller set , they claim that the macho collaboration overestimated the optical depth by a significant factor and that the macho microlensing experiment is consistent with lensing by known stars in the milky way and lmc .
as we show below , the analysis by these authors contains several errors which render their conclusions meaningless .
their efficiency analysis is clearly in error , and since they did not search through the entire macho dataset , they do not know how many microlensing events their neural net would find in the data or what optical depth their method would give .
examination of their selected events suggests that their method misses low s / n events and thus would have lower efficiency than the macho selection criteria .
in addition , their method is likely to give many more false positives ( non - lensing events identified as lensing ) .
both effects would increase their estimated optical depth .
finally , we note that the eros discovery that lmc event-23 is a variable star reduces the macho collaboration estimates of optical depth and macho halo fraction by around 8% , and does open the question of additional contamination .
[ firstpage ] gravitational lensing
galaxy : halo dark matter
magellanic clouds .
And you have already written the first three sentences of the full article: a number of experiments have returned microlensing results on the nature of the dark matter in the milky way .
the eros collaboration ( aubourg , 1993 ; lasserre 2000 ) monitored 17.5 million stars in the lmc for 2 years and 5.3 million stars for 6 years finding 3 microlensing candidates . using these events and an efficiency analysis they found an upper limit of 40% ( 95% c.l . ) on the halo mass fraction in machos in the mass range of @xmath0 to @xmath1 .
the macho collaboration ( alcock , 1993 ; 1997 ; 2000 ) monitored 11.9 million stars in the lmc over 5.7 years , finding between 13 and 17 microlensing candidates ..
Please generate the next two sentences of the article | they did a careful efficiency analysis , including the effect of blending in their crowded fields and found a best fit macho halo fraction of 20% ( @xmath2 at 95% cl ) , which corresponds to an optical depth of @xmath3 .
it is important to realize that the macho estimate of dark matter halo fraction depended crucially on the use of standard models of the milky way thin disc , thick disc , spheroid , halo , and the lmc disc and halo . |
8,798 | Suppose that you have an abstract for a scientific paper: we demonstrate a simple scheme for high - resolution imaging of nanoplasmonic structures that basically removes most of the resolution limiting allowed light usually transmitted to the far field .
this is achieved by implementing a fourier lens in a near - field scanning optical microscope ( nsom ) operating in the leakage - radiation microscopy ( lrm ) mode .
the method consists of reconstructing optical images solely from the plasmonic ` forbidden ' light collected in the fourier space .
it is demonstrated by using a point - like nanodiamond - based tip that illuminates a thin gold film patterned with a sub - wavelength annular slit .
the reconstructed image of the slit shows a spatial resolution enhanced by a factor @xmath0 compared to nsom images acquired directly in the real space .
99 b. hecht , d. w. pohl , h. heinzelmann , and l. novotny , tunnel near - field optical microscopy : tnom-2 , " ultramicroscopy * 61 * , 99 - 104 ( 1995 ) .
b. hecht , h. bielefeldt , l. novotny , y. inouye , and d. w. pohl , local excitation , scattering , and interference of surface plasmons , " phys .
rev .
lett . * 77 * , 1889 - 1892 ( 1996 ) . c. chicane , t. david , r. quidant , j .- c .
weeber , y. lacroute , e. bourillot , a. dereux , g. colas des francs , and c. girard , imaging the local density of states of optical corrals , " phys .
rev .
lett . * 88 * , 097402 ( 2002 ) .
a. bouhelier , th .
huser , h. tamaru , h .- j .
gntherodt , and d. w. pohl,``plasmon optics of structured silver films , '' phys .
rev .
b * 63 * , 155404 ( 2001 ) .
a. drezet , a. hohenau , a. l. stepanov , h. ditlbacher , b. steinberger , n. galler , f. r. aussenegg , a. leitner , and j. r. krenn , how to erase surface plasmon fringes , " appl .
. lett . * 89 * , 091117 ( 2006 ) .
d. e. chang , a. s. srensen , p. r. hemmer , and m. d. lukin , quantum optics with surface plasmons , " phys .
rev .
lett . * 97 * , 053002 ( 2006 ) .
a. v. akimov , a. mukherjee , c. l. yu , d. e. chang , a. s.....
And you have already written the first three sentences of the full article: a sub - wavelength object diffracts light into evanescent and propagating waves .
it is the evanescent part - the so - called forbidden light - that carries information on the sub - wavelength details of the object .
this evanescent contribution plays a key role in experiments targeted at imaging surface - plasmon polaritons ( spps ) , which are electron - photon hybrid states naturally confined at the boundary between a metal and an insulator . as such ,.
Please generate the next two sentences of the article | spps are strongly modified by local changes of their environment at the nanoscale and it is therefore critical to find efficient methods to probe the interaction of spps with nanostructures .
this constitutes the central motivation of the present work . in this context |
8,799 | Suppose that you have an abstract for a scientific paper: we examine spectral properties of doped holes dressed with surrounding spin cloud in the @xmath0-@xmath1 model .
these composite - hole excitations well characterize prominent band structures in the angle - resolved photoemission spectrum .
in one - dimensional ( 1d ) case at half - filling , we identify the composite operators that separately pick up the spinon and holon branches , respectively .
after hole doping , we find that the composite hole excitations with string - like spins tend to be localized at @xmath2 in the momentum space .
this means that such composite excitations should be actual electronic excitations , since the spinon and holon branches merge together at this momentum . in 2d case
, we find that the composite excitations with more non - local spin fluctuation have stronger intensity near the fermi level .
the composite band structure along diagonal @xmath3-@xmath4 direction in 2d has some similarity to that in 1d , and such non - local spin fluctuation plays an important role on the formation of the pseudogap in high-@xmath5 cuprates . .
And you have already written the first three sentences of the full article: the @xmath0-@xmath1 model is one of prototypical examples for understanding strongly correlated electron systems .
the interplay between spin and charge degrees of freedom is a key ingredient of this model . in
spatially one - dimensional ( 1d ) case , this model ( or equivalently the large-@xmath6 hubbard model ) has been fully understood by the exact and numerical approaches @xcite ..
Please generate the next two sentences of the article | therein , the electronic band dispersion splits into the spinon and holon branches , and this is called the spin - charge separation .
they are collective excitations , not the quasiparticles . in 2d case |
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