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4,800 | Suppose that you have an abstract for a scientific paper: this presentation reviews chandra s major contribution to the understanding of nearby galaxies . after a brief summary on significant advances in characterizing various types of discrete x - ray sources , the presentation focuses on the global hot gas in and around galaxies , especially normal ones like our own .
the hot gas is a product of stellar and agn feedback the least understood part in theories of galaxy formation and evolution .
chandra observations have led to the first characterization of the spatial , thermal , chemical , and kinetic properties of the gas in our galaxy .
the gas is concentrated around the galactic bulge and disk on scales of a few kpc .
the column density of chemically - enriched hot gas on larger scales is at least an order magnitude smaller , indicating that it may not account for the bulk of the missing baryon matter predicted for the galactic halo according to the standard cosmology .
similar results have also been obtained for other nearby galaxies .
the x - ray emission from hot gas is well correlated with the star formation rate and stellar mass , indicating that the heating is primarily due to the stellar feedback . however
, the observed x - ray luminosity of the gas is typically less than a few percent of the feedback energy .
thus the bulk of the feedback ( including injected heavy elements ) is likely lost in galaxy - wide outflows .
the results are compared with simulations of the feedback to infer its dynamics and interplay with the circum - galactic medium , hence the evolution of galaxies . .
And you have already written the first three sentences of the full article: x - ray observations are playing an increasingly important role in the study of galaxies . with its arcsecond spatial resolution ,
in particular has made a significant impact on our understanding of discrete x - ray source populations , which mostly represent various stellar end - products [ e.g. , low- and high - mass x - ray binaries ( lmxbs and hmxbs ) and supernova remnants ( snrs ) ] as well as active galactic nuclei ( agns ) .
the resolution also allows for a clean excision of such sources from the data so low - surface brightness emission ( e.g. from diffuse hot gas ) can be mapped out . an under - appreciated aspect of is its spectroscopic capability in the study of diffuse hot gas when the low- and high - energy grating instruments are used . although the sensitivities of the instruments are quite limited , the existing observations of a dozen or so bright objects ( agns and lmxbs ) have yielded data of high enough quality for unprecedented x - ray absorption line spectroscopic measurements of the global hot gas in and around our galaxy ..
Please generate the next two sentences of the article | useful constraints have also been obtained on the overall content of hot gas around galaxies within certain impact distances of the sight lines toward the agns .
these measurements , compared with physical models and simulations of the hot gas , are shedding important insights on its relationship to the feedback from stars and agns . |
4,801 | Suppose that you have an abstract for a scientific paper: we study the tidal disruption of neutron stars in black hole - neutron star coalescing binaries .
we calculate the critical orbital separation at which the star is disrupted by the black hole tidal field for several equations of state describing the matter inside the neutron star , and for a large set of the binary parameters .
when the disruption occurs before the star reaches the innermost stable circular orbit , the gravitational wave signal emitted by the system is expected to exhibit a cutoff frequency @xmath0 , which is a distinctive feature of the waveform .
we evaluate @xmath0 and show that , if this frequency will be found in a detected gravitational wave , it will allow one to determine the neutron star radius with an error of a few percent , providing valuable information on the behaviour of matter in the stellar core . .
And you have already written the first three sentences of the full article: the coalescence of neutron star - neutron star ( ns - ns ) and black hole - neutron star ( bh - ns ) binaries is one of the most promising sources of gravitational waves to be detected by ground based gravitational wave detectors like virgo and ligo @xcite .
these detectors have now reached the planned sensitivity and they will evolve toward a second generation , the advanced ( virgo and ligo ) detectors , with a sensitivity enhanced by an order of magnitude .
furthermore , a design study for an even more sensitive third generation detector , et ( einstein telescope ) , is in progress @xcite . in a recent study , based on a population synthesis approach @xcite , the formation and.
Please generate the next two sentences of the article | the evolution of compact binary systems has been followed from the onset of star formation , both in the galactic field , where their massive binary progenitors evolve in isolation , and in dense clusters , where they can form at high rates due to dynamical interactions .
the authors estimate that advanced ligo should detect the merger of ns - ns binaries at a rate of @xmath1 events per year and the merger of bh - ns binaries at a rate of @xmath2 per year . |
4,802 | Suppose that you have an abstract for a scientific paper: we discuss the potential of measurements of @xmath0 to constrain new bosonic degrees of freedom at the lhc when @xmath1 for a pseudorapidity cut @xmath2 . by suppressing the nlo qcd production of @xmath3 pairs through simple kinematic constraints
we show how to more efficiently exploit cms s reach out to @xmath4 in @xmath5 for @xmath6 mesons in searches for new physics . using this technique
we investigate the potential for discovery of new massive spin one and spin zero @xmath7 octet bosons by analyzing their effect on the @xmath8 distribution . in some cases , the tree level contributions are small and the largest effect of new physics on the @xmath5 tail of the distribution is due to one - loop resonant @xmath9-channel production or interference effects with the lo standard model production mechanisms @xmath10 .
we explore this possibility in some detail when the standard model is extended with an @xmath11 scalar motivated by minimal flavor violation . .
And you have already written the first three sentences of the full article: the large hadron collider ( lhc ) will measure the @xmath12 jet production cross section in hadron collisions for various ranges of transverse momenta ( @xmath5 ) with unprecedented statistics and kinematics . with the improvements of @xmath12 tagging pioneered at the tevatron @xcite , the analysis of @xmath12 production with associated muon tags in the lhc environment @xcite is very promising .
studies by the cms collaboration have determined that the final states of @xmath12 production can be triggered on and measured out to @xmath4 in the @xmath5 of inclusive @xmath6 meson production by utilizing @xmath12 jet tagging in events containing at least one muon @xcite . the standard model ( sm )
qcd production mechanism for @xmath3 falls rapidly when @xmath13 , thus , studies with restricted @xmath1 ( for such values of @xmath5 and a pseudorapidity ( @xmath14 ) of @xmath2 the variables @xmath5 and @xmath14 are independent from one another ) offer the opportunity to explore the effect that beyond the sm ( bsm ) physics can have on the @xmath5 tail of the @xmath15 distribution . in utilizing this distribution to search for bsm physics one.
Please generate the next two sentences of the article | has to contend with the fact that nlo qcd production leads to a larger background than lo qcd at high @xmath5 due to a @xmath16-channel singularity in @xmath17 . in this paper
, we argue that the nlo qcd production background can be significantly reduced through simple kinematic cuts . |
4,803 | Suppose that you have an abstract for a scientific paper: we report on calculations of the reduced sedimentation velocity @xmath0 in homogenous suspensions of strongly and weakly charged colloidal spheres as a function of particle volume fraction @xmath1 . for dilute suspensions of strongly charged spheres at low salinity ,
@xmath0 is well represented by the parametric form @xmath2 with a fractional exponent @xmath3 and a parameter @xmath4 , which is essentially independent from the macroion charge @xmath5 .
this non - linear volume fraction dependence can be _ quantitatively _ understood in terms of a model of effective hard spheres with @xmath1-dependent diameter .
for weakly charged spheres in a deionized solvent , we show that the exponent @xmath6 can be equal to @xmath7 , if an expression for @xmath8 given by petsev and denkov [ _ j .
colloid interface sci . _ * 149 * , 329 ( 1992 ) ] is employed .
we further show that the range of validity of this expression is limited to very small values of @xmath1 and @xmath5 , which are probably not accessible in sedimentation experiments .
the presented results might also hold for other systems like spherical proteins or ionic micelles .
* key words : * sedimentation , hydrodynamic interactions , charge - stabilized colloids * short running title : * sedimentation of charged particles .
And you have already written the first three sentences of the full article: the sedimentation velocity @xmath9 of interacting colloidal particles depends both on the indirect hydrodynamic interactions ( hi ) mediated by the suspending solvent , and on the microstructure of the suspension . in equilibrium ,
the latter is determined by direct potential forces arising for example from the steric repulsion between the particles and from the electrostatic repulsion of overlapping double layers .
different pair potentials @xmath10 lead to rather different microstructures , and this in turn strongly effects the sedimentation ..
Please generate the next two sentences of the article | it is well established by theories and experiments that the sedimentation velocity of a dilute suspension of monodisperse hard spheres is given by @xmath11 where @xmath1 is the particle volume fraction , and @xmath12 is the sedimentation velocity at infinite dilution @xcite . on the other hand , the long - ranged electrostatic repulsion occurring in suspensions of charged particles can give rise to a reduction in @xmath9 , as compared to a hard sphere dispersion at the same volume fraction @xcite . this decrease in @xmath9
is mainly due to the cumulative backflow of displaced fluid , which becomes particularly effective because the probability of two or more charged particles coming close to each other is very small . |
4,804 | Suppose that you have an abstract for a scientific paper: an operational monitoring , as well as high resolution local - scale meteorological and air quality forecasting information system for western macedonia , hellas , has been developed and is operated by the laboratory of atmospheric pollution and environmental physics / tei western macedonia since 2002 , continuously improved . in this paper the novelty of information system is presented , in a dynamic , easily accessible and user - friendly manner .
it consists of a structured system that users have access to and they can manipulate thoroughly , as well as of a system for accessing and managing results of measurements in a direct and dynamic way .
it provides updates about the weather and pollution forecast for the next few days ( based on current day information ) in western macedonia .
these forecasts are displayed through dynamic - interactive web charts and the visual illustration of the atmospheric pollution of the region in a map using images and animation images . .
And you have already written the first three sentences of the full article: web applications constitute valuable up - to - date tools in a number of different cases .
one such case is their use in the management of environmental problems so as to protect civilians from any unfortunate consequences that these problems can cause . their evolution , therefore , has been especially important in many cases , one of them being in the development of systems of administration of the air quality @xcite.the right of accessing environmental information has been enacted in european level through appropriate legislation , which are incorporated in the relevant greek legislation see @xcite- @xcite .
nowadays , the combination of telecommunications and new technologies create a framework for developing such systems increasingly sophisticated @xcite- @xcite ..
Please generate the next two sentences of the article | that is just diffusion of environmental information and public access which was attempted effectively through the system codenamed eap ( laboratory of atmospheric pollution and environmental physics ) in western macedonia .
it is developed for the first time in 2002 @xcite , providing the possibility for direct information to the public about the air quality , as it was recorded in the four atmospheric measurement stations established in the capitals of countries kozani , florina , kastoria and grevena though an appropriate web - site , as well as sms , with the possibility for extension of stations and also the historical measurements privilege @xcite . for every station a previous and current index of pollution appears ( in a scale 1 - 10 ) with an appropriate colour scale @xcite . |
4,805 | Suppose that you have an abstract for a scientific paper: we report on the discovery of a high - velocity narrow absorption line outflow in the redshift 2.3 quasar j212329.46 - 005052.9 .
five distinct outflow systems are detected with velocity shifts from @xmath09710 to @xmath014,050 km s@xmath1 and @xmath2@xmath21548,1551 line widths of fwhm @xmath3 62 to 164 km s@xmath1 .
this outflow is remarkable for having high speeds and a degree of ionization similar to broad absorption line ( bal ) flows , but line widths roughly 100 times narrower than bals and no apparent x - ray absorption .
this is also , to our knowledge , the highest - velocity narrow absorption line system confirmed to be in a quasar outflow by all three indicators of line variability , smooth super - thermal line profiles and doublet ratios that require partial covering of the quasar continuum source .
all five systems have stronger absorption in @xmath2@xmath21032,1038 than with no lower ionization metal lines detected .
their line variabilities also appear coordinated , with each system showing larger changes in than and line strength variations accompanied by nearly commensurate changes in the absorber covering fractions .
the metallicity is approximately twice solar .
these data require five distinct outflow structures with similar kinematics , physical conditions and characteristic sizes of order 0.01 - 0.02 pc ( based on partial covering ) .
the coordinated line variations , occurring on time scales @xmath40.63 yr ( quasar frame ) , are best explained by global changes in the outflow ionization caused by changes in the quasar s ionizing flux
. an upper limit on the acceleration , @xmath53 km s@xmath1 yr@xmath1 , is consistent with blobs of gas that are gravitationally unbound and coasting freely @xmath65 pc from the central black hole .
additional constraints from the variability time indicate that the full range of plausible distances is @xmath7 pc .
however , if these small absorbing structures were created in the inner flow , they should be near the....
And you have already written the first three sentences of the full article: high - velocity outflows from quasars appear to be a natural part of the accretion process .
they are detected most conspicuously via broad absorption lines ( bals ) in quasar spectra , with velocity widths @xmath102000 km s@xmath1 ( by definition , * ? ? ?
* ) and flow speeds from a few thousand to roughly 10,000 - 30,000 km s@xmath1 ( see also * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
however , quasar outflows can also produce narrow absorption lines ( nals ) , with velocity widths less than a few hundred km s@xmath1 , as well as mini - bals , which are loosely defined as intermediate between nals and bals ( e.g. , * ? ? ? |
4,806 | Suppose that you have an abstract for a scientific paper: applications of a simple thermal model to ultra - relativistic heavy - ion collisions are presented .
we compute abundances of various hadrons , including particles with strange quarks , the @xmath0-spectra , and the hbt radii for the pion .
surprising agreement is found , showing that the thermal approach can be used successfully to understand and describe the rhic data . .
And you have already written the first three sentences of the full article: with the wide stream of new high - quality data flowing from rhic , as well as with the continued efforts at sps ( for recent results see , _
e.g. _ , @xcite ) , there is a growing need for a simple description of the basic underlying physics .
only then our understanding of the phenomena occurring in ultra - relativistic heavy - ion collisions can be pushed forward , and space made for potential new phenomena , hitherto unexplained within the basic picture . in this lecture.
Please generate the next two sentences of the article | we argue that most of the `` soft '' features of the data from rhic ( particle ratios , momentum spectra , hbt correlation radii ) can be explained very efficiently within an embarrassingly simple model , which merges the thermal model @xcite with expansion , and incorporates in a complete way the resonances @xcite .
our description uses hadronic degrees of freedom and starts at freeze - out , _ |
4,807 | Suppose that you have an abstract for a scientific paper: correlation studies exhibit a ridge - like feature in rapidity and azimuthal angle , with and without a jet trigger .
we ask whether the feature in untriggered correlations can be a consequence of transverse flow and viscous diffusion .
jet correlation measurements display a ridge of enhanced particle emission that is broad in pseudorapidity @xmath0 and narrow in azimuthal angle @xmath1 @xcite .
many have attributed this ` hard ridge ' to the passage of the jet through the high - density environment produced by the nuclear collision ; see e.g. @xcite .
interestingly , a similar ridge feature is exhibited in untriggered correlation studies where no jet tag is present @xcite .
as with the hard ridge , the width of the untagged ` soft ridge ' broadens in @xmath0 and narrows in @xmath1 for collisions of higher centrality ( smaller impact parameter ) .
we ask whether the @xmath2 dependence of the soft ridge in untagged correlations can be a consequence of radial flow and viscous diffusion .
the connection between radial flow and momentum correlations has been stressed elsewhere @xcite . in ref
. @xcite we attributed the rapidity broadening of untriggered momentum correlations to viscous diffusion , extracting an estimate of the viscosity - to - entropy ratio in the range from @xmath3 to @xmath4 . in this paper
we show that viscous diffusion together with flow can explain the centrality dependence of the soft ridge ; see fig . 1 ( right ) . the soft ridge has been observed both in momentum fluctuation studies @xcite and multiplicity correlation measurements @xcite . here , we focus on the momentum correlation results , which we argue depend strongly on the viscosity of the high density liquid produced in collisions .
our hope is to eventually reduce the rather large uncertainty in the viscosity estimate in @xcite by using the full landscape of @xmath5 correlations , rather than just the @xmath0 dependence . in this paper
, we first recall the role of shear viscosity in the....
And you have already written the first three sentences of the full article: 10 j. putschke , j. phys .
g * 34 * , s679 ( 2007 ) [ arxiv : nucl - ex/0701074 ] .
r. c. hwa and c. b. yang , arxiv:0801.2183 [ nucl - th ] ; c. y. wong , arxiv:0804.4017 [ hep - ph ] ..
Please generate the next two sentences of the article | m. daugherity [ star collaboration ] , pos c * frnc2006 * , 005 ( 2006 ) [ arxiv : nucl - ex/0611032 ] .
s. a. voloshin , phys . |
4,808 | Suppose that you have an abstract for a scientific paper: a large class of evolutionary processes can be modeled by a rule that involves self - replication of some physical quantity with a non local rescaling .
we show that a class of such models are exactly solvable in the discrete as well as continuum limit and can represent several physical situations as varied from the formation of galaxies in some cosmological models to growth of bacterial cultures .
this class of models , in general , has no steady state solution and evolve unstably as @xmath0 for generic initial conditions
. they can however exhibit ( unstable ) power law correlation function in the continuum limit , for an intermediate range of times and length scales . .
And you have already written the first three sentences of the full article: observations show that the two point correlation function of the galaxies is an approximate power law over a range of scales .
this result , known for decades now , defies a simple first - principle " explanation because of the complexity of the physical processes involved . in the conventional big - bang cosmology
the dominant contribution to the energy density of the universe is in the form of nonbaryonic dark matter and the visible galaxies ( made of baryons ) form due to complex processes of cooling and fragmentation within the dark matter halos ..
Please generate the next two sentences of the article | it is possible to model non linear gravitational clustering of _ dark matter halos _ by a scaling ansatz ( see eg .
@xcite ) and show that a power law correlation is expected ( in a spatial and temporal interval ) for scale invariant initial conditions . |
4,809 | Suppose that you have an abstract for a scientific paper: in this work we examine a nonlinear version of the jaynes - cummings model for two identical two - level atoms allowing for ising - like and dipole - dipole interplays between them .
the model is said to be nonlinear in the sense that it can incorporate both a general intensity - dependent interaction between the atomic system and the cavity field and/or the presence of a nonlinear medium inside the cavity . as an example
, we consider a particular type of atom - field coupling based upon the so - called buck - sukumar model and a lossless kerr - like cavity .
we describe the possible effects of such features on the evolution of some quantities of current interest , such as atomic excitation , purity , concurrence , the entropy of the field and the evolution of the latter in phase space . .
And you have already written the first three sentences of the full article: the standard jaynes - cummings model ( jcm ) is usually referred to as the simplest fully quantized light - matter interaction scheme involving just one atom and one mode of the radiation field . since its introduction in 1963 @xcite , the model has attracted a great deal of theoretical and experimental interest in the fields of laser physics and quantum optics @xcite , and this trend is due in part to its apparent simplicity and , more importantly , to its striking predictions about the dynamical properties of the subsystems involved with which the quantum optics community is now familiar , as for example the well - known phenomenon of _ collpases _ and _ revivals _ for the atomic excitation understood in terms of the grainy statistics of the radiation field @xcite .
+ the jcm has become the source of inspiration for a wide variety of generalizations dealing with more general and/or realistic circumstances .
the majority of them focused primarily upon multi - photon transitions and/or multimode fields @xcite ; engineering nonlinear atom - field couplings , like the buck - sukumar and kochetov models @xcite ( including some very recent improvements and extensions of the former with or without applying the rotating wave approximation @xcite ) , one - atom jc models involving two - photon interaction with intensity - dependence both in the atom - field coupling and the detuning @xcite , or adding nonlinear kerr - like media @xcite ; interacting or noninteracting two two - level atoms @xcite ; or even more complex systems involving a large group of @xmath0 two - level ( or multi - level ) atoms in the same cavity , such as the so - called tavis - cummings model ( tcm ) @xcite , to mention some examples . and still more recently , renewed attention has been paid to quantum decoherence and entanglement properties of light - matter interaction models la jaynes - cummings whose central system is composed of two or three two - level atoms ( also called within the jargon of the quantum information framework as two-....
Please generate the next two sentences of the article | + this work is in keeping with the aforementioned spirit of putting forward another extension of the jaynes - cummings model , that is , a nonlinear version of it for the description of a qubit system composed of two identical two - level atoms that interact with each other via dipole - dipole and ising - like interaction and with a one - mode cavity field being in a coherent superposition of number states .
the nonlinear character of the model is construed in a twofold sense : i ) the interaction between the atomic system and the field is considered to be nonlinear in a way such that it hinges on the number of photons of the latter , and ii ) the said atomic system can be allowed to be embedded in a kind of nonlinear medium inside the cavity . in considering a buck - sukumar nonlinear coupling @xcite between the atoms and the field and a kerr - like medium within the cavity as particular cases , a full algebraic solution of the problem is provided and the consequences of incorporating such nonlinearities are illustrated by exploring , in the resonant quantum dynamics , some quantities of current physical interest , such as population inversion , purity , and concurrence , as far as the atomic system is concerned , and the time behavior of the field itself is also investigated in terms of its entropy and its image on phase space . it is worth commenting that the set of results reported here , regarding the aforesaid nonlinear coupling scheme , may also be of some relevance in the light of novel experimental and theoretical research on optical simulation of the jaynes - cummings and rabi models in arrays of coupled photonic waveguides @xcite , as well as in current designs of architectures intended for quantum computation and communication based on cavity quantum electrodynamics ( cqed ) studies for solid - state superconducting electrical circuits @xcite . |
4,810 | Suppose that you have an abstract for a scientific paper: a @xmath0-orbit maniplex is one that has @xmath0 orbits of flags under the action of its automorphism group . in this paper
we extend the notion of symmetry type graphs of maps to that of maniplexes and polytopes and make use of them to study @xmath0-orbit maniplexes , as well as fully - transitive 3-maniplexes .
in particular , we show that there are no fully - transtive @xmath0-orbit 3-mainplexes with @xmath1 an odd number , we classify 3-orbit mainplexes and determine all face transitivities for 3- and 4-orbit maniplexes .
moreover , we give generators of the automorphism group of a polytope or a maniplex , given its symmetry type graph . finally , we extend these notions to oriented polytopes , in particular we classify oriented 2-orbit maniplexes and give generators for their orientation preserving automorphism group . .
And you have already written the first three sentences of the full article: while abstract polytopes are a combinatorial generalisation of classical polyhedra and polytopes , maniplexes generalise maps on surfaces and ( the flag graph of ) abstract polytopes .
the combinatorial structure of maniplexes , maps and polytopes is completely determined by a edge - coloured @xmath2-valent graph with chromatic index @xmath2 , often called the flag graph .
the symmetry type graph of a map is the quotient of its flag graph under the action of the automorphism group . in this paper.
Please generate the next two sentences of the article | we extend the notion of symmetry type graphs of maps to that of maniplexes ( and polytopes ) .
given a maniplex , its symmetry type graph encapsulates all the information of the local configuration of the flag orbits under the action of the automorphism group of the maniplex . |
4,811 | Suppose that you have an abstract for a scientific paper: in addition to constraining bilateral exposures of financial institutions , there are essentially two options for future financial regulation of systemic risk ( sr ) : first , financial regulation could attempt to reduce the financial fragility of global or domestic systemically important financial institutions ( g - sibs or d - sibs ) , as for instance proposed in basel iii .
second , future financial regulation could attempt strengthening the financial system as a whole .
this can be achieved by re - shaping the topology of financial networks .
we use an agent - based model ( abm ) of a financial system and the real economy to study and compare the consequences of these two options . by conducting three `` computer experiments '' with the abm we find that re - shaping financial networks
is more effective and efficient than reducing leverage . capital surcharges for g - sibs can reduce sr , but must be larger than those specified in basel iii in order to have a measurable impact .
this can cause a loss of efficiency .
basel iii capital surcharges for g - sibs can have pro - cyclical side effects . .
And you have already written the first three sentences of the full article: six years after the financial crisis of 2007 - 2008 , millions of households worldwide are still struggling to recover from the aftermath of those traumatic events .
the majority of losses are indirect , such as people losing homes or jobs , and for the majority , income levels have dropped substantially . for the economy as a whole , and for households and for public budgets , the miseries of the market meltdown of 2007 - 2008 are not yet over.as a consequence , a consensus for the need for new financial regulation is emerging @xcite .
future financial regulation should be designed to mitigate risks within the financial system as a whole , and should specifically address the issue of systemic risk ( sr ) ..
Please generate the next two sentences of the article | sr is the risk that the financial system as a whole , or a large fraction thereof , can no longer perform its function as a credit provider , and as a result collapses . in a narrow sense , it is the notion of contagion or impact from the failure of a financial institution or group of institutions on the financial system and the wider economy @xcite .
generally , it emerges through one of two mechanisms , either through interconnectedness or through the synchronization of behavior of agents ( fire sales , margin calls , herding ) . |
4,812 | Suppose that you have an abstract for a scientific paper: fu orionis ( fuor ) outbursts are major optical brightening episodes in low - mass protostars that evidently correspond to rapid mass - accretion events in the innermost region of a protostellar disc .
the outbursts are accompanied by strong outflows , with the inferred mass outflow rates reaching @xmath0 of the mass inflow rates .
shu et al . proposed that the outflows represent accreted disc material that is driven centrifugally from the spun - up surface layers of the protostar by the stellar magnetic field .
this model was critiqued by calvet et al . , who argued that it can not reproduce the photospheric absorption - line shifts observed in the prototype object fu ori .
calvet et al . proposed that the wind is launched , instead , from the surface of the disc on scales of a few stellar radii by a non - stellar magnetic field . in this paper we present results from numerical simulations of disc accretion on to a slowly rotating star with an aligned magnetic dipole moment that gives rise to a kilogauss - strength surface field .
we demonstrate that , for parameters appropriate to fu ori , such a system can develop a strong , collimated disc outflow of the type previously identified by romanova et al . in simulations of protostars with low and moderate accretion rates . at the high accretion rate that characterizes the fuor outburst phase , the radius @xmath1 at which the disc is truncated by the stellar magnetic field moves much closer to the stellar surface , but the basic properties of the outflow , which is launched from the vicinity of @xmath1 along opened - up stellar magnetic field lines , remain the same .
these properties are distinct from those of the x - celerator ( or the closely related x - wind ) mechanism proposed by shu et al . in particular
, the outflow is driven from the start by the magnetic pressure - gradient force , not centrifugally , and it is more strongly collimated .
we show that the simulated outflow can in principle account for the main observed....
And you have already written the first three sentences of the full article: fu orionis systems ( hereafter fuors ) , named after their prototype object , are low - mass ( sun - like ) protostars that undergo a rapid accretion episode in the innermost region of the circumstellar disc ( see @xcite for a review ) .
the gravitational energy released in such an event leads to an emission outburst ( with a rise time of @xmath2yr and a duration of @xmath3yr ) , during which the disc is more luminous than the central protostar by a factor of @xmath4 .
the inferred mass accretion rate during the outburst is @xmath5 , much higher than typical accretion rates during the quiescent phase ..
Please generate the next two sentences of the article | statistical arguments , first advanced by @xcite , indicate that such outbursts occur , on average , ten or more times during the protostellar lifetime .
there is evidence that the outbursts are more frequent during the early ( the so - called class 0 and class i ) evolutionary phases and peter out as the mass accretion rate declines and the protostar enters the visible ( class ii , or classical t tauri ) phase . |
4,813 | Suppose that you have an abstract for a scientific paper: the detection of x - ray narrow spectral features in the 5 - 7 kev band is becoming increasingly more common in agn observations , thanks to the capabilities of current x - ray satellites .
such lines , both in emission and in absorption , are mostly interpreted as arising from iron atoms . when observed with some displacement from their rest frame position
, these lines carry the potential to study the motion of circumnuclear gas in agn , providing a diagnostic of the effects of the gravitational field of the central black hole .
these narrow features have been often found with marginal statistical significance .
we are carrying on a systematic search for narrow features using spectra of bright type1 agns available in the _ xmm - newton _ archive .
the aim of this work is to characterise the occurrence of the narrow features phenomenon on a large sample of objects and to estimate the significance of the features through monte carlo simulations .
the project and preliminary results are presented .
address = european space astronomy centre , apartado 50727 e-28080 , madrid , spain .
And you have already written the first three sentences of the full article: the presence of fe k features in the spectra of agn and the interpretation on their origin are nowadays quite well established .
fe k@xmath0 transitions give rise to fluorescence emission lines .
the neutral fe k line at 6.4 kev is usually the most prominent in agn spectra . an unresolved component of this transition is almost ubiquitous in xmm - newton agn spectra ( bianchi et al ..
Please generate the next two sentences of the article | 2004 , page et al .
2004 , jimnez - bailn et al . |
4,814 | Suppose that you have an abstract for a scientific paper: we explore with exact diagonalization the propagation of a single hole in four magnetic phases of the @xmath0-@xmath1-like kitaev - heisenberg model on a honeycomb lattice : the nel antiferromagnetic , stripe , zigzag and kitaev spin - liquid phase .
we find coherent propagation of spin - polaron quasiparticles in the antiferromagnetic phase by a similar mechanism as in the @xmath0-@xmath1 model for high-@xmath2 cuprates . in the stripe and zigzag phases clear quasiparticles features appear in spectral functions of those propagators where holes are created and annihilated on one sublattice , while they remain largely _ hidden _ in those spectral functions that correspond to photoemission experiments . as the most surprising result , we find a totally incoherent spectral weight distribution for the spectral function of a hole moving in the kitaev spin - liquid phase in the strong coupling regime relevant for iridates . at intermediate coupling
the finite systems calculation reveals a well defined quasiparticle at the @xmath3 point , however , we find that the gapless spin excitations wipe out quasiparticles at finite momenta . also for this more subtle case we conclude that in the thermodynamic limit the lightly doped kitaev liquid phase does not support quasiparticle states in the neighborhood of @xmath3 , and therefore yields a _ non - fermi liquid _ , contrary to earlier suggestions based on slave - boson studies .
these observations are supported by the presented study of the dynamic spin - structure factor for the kitaev spin liquid regime . .
And you have already written the first three sentences of the full article: carrier propagation in mott or charge - transfer insulators is a challenging problem particularly motivated by strongly correlated superconducting cuprates @xcite .
while holes move incoherently in one - dimensional systems featuring charge and spin separation @xcite as well as in systems with antiferromagnetic ( af ) ising interactions @xcite , the hole motion becomes coherent and quasiparticles ( qps ) arise at low energy in the quantum af @xmath0-@xmath1 model @xcite .
these qps are indeed observed in angle - resolved photoemission ( arpes ) experiments in cuprates @xcite . in general , low - energy qps coexist with incoherent processes at high energy , as in the af phase on the square @xcite or honeycomb lattice @xcite ..
Please generate the next two sentences of the article | this is however not always the case as shown by arpes experiments for the spin - orbit mott insulator na@xmath4iro@xmath5 @xcite , without clear evidence for qps at low energy @xcite . in a recent study hole - doped li@xmath4ir@xmath6ru@xmath7o@xmath5 with honeycomb structure
was found insulating at all doping levels @xcite . |
4,815 | Suppose that you have an abstract for a scientific paper: we present the results of extensive observations by the gamma - ray agile satellite of the galactic region hosting the carina nebula and the remarkable colliding wind binary eta carinae ( ) during the period 2007 july 2009 january .
we detect a gamma - ray source ( ) consistent with the position of .
if is associated with the car system our data provide the long sought first detection above 100 mev of a colliding wind binary .
the average gamma - ray flux above 100 mev and integrated over the pre - periastron period 2007 july 2008 october is @xmath0 corresponding to an average gamma - ray luminosity of @xmath1 for a distance of 2.3 kpc .
we also report a 2-day gamma - ray flaring episode of on 2008 oct .
11 - 13 possibly related to a transient acceleration and radiation episode of the strongly variable shock in the system . .
And you have already written the first three sentences of the full article: @xmath2 car is a very massive ( @xmath3 solar masses ) star known for its strong mass outflow eruptions , and is one of the most interesting objects of our galaxy ( e.g. , davidson & humphrey 1997 ) .
radial velocity variations of spectroscopic lines accumulated over the years provide a strong evidence that is a binary system ( e.g. , damineli et al .
2008a , b ) where the primary star is a luminous blue variable ( lbv ) star orbiting in a very eccentric binary ( @xmath4 ) with a companion star believed to be an o star of @xmath5 solar masses ..
Please generate the next two sentences of the article | the orbital period is 5.53 years ( @xmath62023 days ) ( e.g. , damineli et al . , 2008a ) : the system has been monitored in the radio , mm , ir , optical and x - ray bands for at least three cycles .
both stars emit dense and high - velocity gaseous winds , and the binary system is ideal to study the interaction of colliding winds and to test theories of particle acceleration and radiation under extreme conditions . |
4,816 | Suppose that you have an abstract for a scientific paper: we consider the problem of incrementally solving a sequence of quantified boolean formulae ( qbf ) .
incremental solving aims at using information learned from one formula in the process of solving the next formulae in the sequence . based on a general overview of the problem and related challenges , we present an approach to incremental qbf solving which is application - independent and hence applicable to qbf encodings of arbitrary problems .
we implemented this approach in our incremental search - based qbf solver and report on implementation details .
experimental results illustrate the potential benefits of incremental solving in qbf - based workflows . .
And you have already written the first three sentences of the full article: the success of sat technology in practical applications is largely driven by _ incremental solving_. sat solvers based on conflict - driven clause learning ( cdcl ) @xcite gather information about a formula in terms of learned clauses .
when solving a sequence of closely related formulae , it is beneficial to keep clauses learned from one formula in the course of solving the next formulae in the sequence .
the logic of quantified boolean formulae ( qbf ) extends propositional logic by universal and existential quantification of variables ..
Please generate the next two sentences of the article | qbf potentially allows for more succinct encodings of pspace - complete problems than sat .
motivated by the success of incremental sat solving , we consider the problem of incrementally solving a sequence of syntactically related qbfs in prenex conjunctive normal form ( pcnf ) . building on search - based qbf solving with clause and cube learning ( qcdcl ) @xcite |
4,817 | Suppose that you have an abstract for a scientific paper: we study the transfer of electromagnetic energy across a subwavelength gap separating two co - axial metal nanorodes .
the absence of spacer in the gap separating the rods the system exhibits the strong coupling between longitudinal plasmons in the two rods .
the nature and magnitude of this coupling is studied by varying various geometrical parameters .
when the length of one rod is varied this mode spectrum exhibits the familiar anti - crossing behavior that depends on the coupling strength determined by the gap width . as a function of frequency
the transmission is dominated by a splitted longitudinal plasmon peak .
the two hybrid modes are the dipole - like `` bonding '' mode characterized by a peak intensity in the gap , and a quadrupole - like `` antibonding '' mode whose amplitude vanishes at the gap center . when off - resonant @xmath0level emitters are placed in the gap , almost no effect on the frequency dependent transmission
is observed .
in contrast , when the molecular system is resonant with the plasmonic lineshape , the transmission is strongly modified , showing characteristics of strong exciton - plasmon coupling , modifying mostly the transmission near the lower frequency `` bonding '' plasmon mode .
the presence of resonant molecules in the gap affects not only the molecule - field interaction but also the spatial distribution of the field intensity and the electromagnetic energy flux across the junction . .
And you have already written the first three sentences of the full article: studies aimed at understanding the consequences of the interaction of electromagnetic fields with metal , semiconductor and molecular nanostructures under the effort to construct , characterize , manipulate and control plasmonic devices @xcite . recurring themes in these studies are the plasmonic response of aggregates of nano - particles @xcite , and the possibility to transmit electromagnetic energy over constrictions substantially smaller than the radiation wavelength .
composite structures ( metal - dielectric , metal - semiconductor ) are often found useful because light can localize at their interfaces .
of particular importance are metal- molecule composites where strong plasmon - exciton coupling together with the non - linear optical response of the molecular system can generate new physical behavior on one hand and provide more control capabilities by tuning the molecular subsystem on the other . in this paper.
Please generate the next two sentences of the article | we study a class of systems of the latter kind , focusing on the light transmission properties of a model system comprising metal rods and molecular aggregates of sub - wavelength dimensions .
transmission properties of nano - size structure are usually discussed in two connotations . |
4,818 | Suppose that you have an abstract for a scientific paper: we describe combinatorial approaches to the question of whether families of real matrices admit pairs of nonreal eigenvalues passing through the imaginary axis .
when the matrices arise as jacobian matrices in the study of dynamical systems , these conditions provide necessary conditions for hopf bifurcations to occur in parameterised families of such systems .
the techniques depend on the spectral properties of additive compound matrices : in particular , we associate with a product of matrices a signed , labelled digraph termed a @xmath0}$ ] graph , which encodes information about the second additive compound of this product .
a condition on the cycle structure of this digraph is shown to rule out the possibility of nonreal eigenvalues with positive real part .
the techniques developed are applied to systems of interacting elements termed `` interaction networks '' , of which networks of chemical reactions are a special case .
hopf bifurcation ; compound matrices ; interaction networks + * msc .
* 15a18 ; 15a75 ; 05c90 ; 34c23 ; 37c27 .
And you have already written the first three sentences of the full article: the material in this paper can be motivated both by abstract questions in linear algebra about the spectra of sets of matrices , and by the study of asymptotic behaviour in dynamical systems .
the connection is quite natural : given a sufficiently smooth dynamical system , the structure or spectra of the jacobian matrices associated with the system may determine certain behaviours , for example the possibility of various local bifurcations , and more generally the possibility of multiple steady states , oscillations or chaos . given a set @xmath1 and a map @xmath2 , define @xmath3 we may ask , for example : 1 .
`` is @xmath4 ? '' 2 ..
Please generate the next two sentences of the article | `` does @xmath5 intersect the imaginary axis ? '' 3 .
`` does the nonreal part of @xmath6 intersect both left and right open half - planes of @xmath7 ? '' and so forth . |
4,819 | Suppose that you have an abstract for a scientific paper: this paper provides the first study of a new dynamical instability in superfluids .
this instability is similar to the two - stream instability known to operate in plasmas .
it is analogous to the kelvin - helmholtz instability , but has the distinguishing feature that the two fluids are interpenetrating .
the instability sets in once the relative flow between the two components of the system reaches a critical level .
our analysis is based on the two - fluid equations that have been used to model the dynamics of the outer core of a neutron star , where superfluid neutrons are expected to coexist with superconducting protons and relativistic electrons .
these equations are analogous to the standard landau model for superfluid helium .
we study this instability for two different model problems .
first we analyze a local dispersion relation for waves in a system where one fluid is at rest while the other flows at a constant rate .
this provides a proof of principle of the existence of the two - stream instability for superfluids .
our second model problem concerns two rotating fluids confined within an infinitesimally thin spherical shell .
the aim of this model is to assess whether the two - stream instability may be relevant ( perhaps as a trigger mechanism ) for pulsar glitches .
our results for this problem show that the entrainment effect could provide a sufficiently strong coupling for the instability to set in at a relative flow small enough to be astrophysically plausible . .
And you have already written the first three sentences of the full article: in this paper we describe a new dynamical instability in superfluids .
this `` two - stream '' instability is analogous to the kelvin - helmholtz instability @xcite .
its key distinguishing feature is that the two fluids are interpenetrating rather than in contact across an interface as in the standard scenario ..
Please generate the next two sentences of the article | the two - stream instability is well known in plasma physics [ where it is sometimes referred to as the `` farley - buneman '' instability @xcite ] , and it has also been discussed in various astrophysical contexts like merging galaxies @xcite and pulsar magnetopheres @xcite , but as far as we are aware it has not been previously considered for superfluids . in fact , the `` standard '' kelvin - helmholtz instability was only recently discussed in the context of superfluids @xcite . the similarity of the equations used in plasma physics [ a nice pedagogical description of the plasma two - stream instability can be found in @xcite ] to the ones for two - fluid superfluid models inspired us to ask whether an analogous instability could be relevant for superfluids .
that this ought to be the case seemed inevitable . to prove the veracity of this expectation , we have adapted the arguments from the plasma problem to the superfluid case , and discuss various aspects of the two - stream instability in this paper . of particular interest to us |
4,820 | Suppose that you have an abstract for a scientific paper: many algorithms have been proposed for fitting network models with communities , but most of them do not scale well to large networks , and often fail on sparse networks . here
we propose a new fast pseudo - likelihood method for fitting the stochastic block model for networks , as well as a variant that allows for an arbitrary degree distribution by conditioning on degrees .
we show that the algorithms perform well under a range of settings , including on very sparse networks , and illustrate on the example of a network of political blogs .
we also propose spectral clustering with perturbations , a method of independent interest , which works well on sparse networks where regular spectral clustering fails , and use it to provide an initial value for pseudo - likelihood .
we prove that pseudo - likelihood provides consistent estimates of the communities under a mild condition on the starting value , for the case of a block model with two communities . , , + .
And you have already written the first three sentences of the full article: analysis of network data is important in a range of disciplines and applications , appearing in such diverse areas as sociology , epidemiology , computer science , and national security , to name a few .
network data here refers to observed edges between nodes , possibly accompanied by additional information on the nodes and/or the edges , for example , edge weights .
one of the fundamental questions in analysis of such data is detecting and modeling community structure within the network ..
Please generate the next two sentences of the article | a lot of algorithmic approaches to community detection have been proposed , particularly in the physics literature ; see @xcite for reviews .
these include various greedy methods such as hierarchical clustering ( see @xcite for a review ) and algorithms based on optimizing a global criterion over all possible partitions , such as normalized cuts @xcite and modularity . |
4,821 | Suppose that you have an abstract for a scientific paper: the study of silicon ( si ) isotopes in ocean island basalts ( oib ) has the potential to discern between different models for the origins of geochemical heterogeneities in the mantle . relatively large ( @xmath0several per mil per atomic mass unit )
si isotope fractionation occurs in low - temperature environments during biochemical and geochemical precipitation of dissolved si , where the precipitate is preferentially enriched in the lighter isotopes relative to the dissolved si .
in contrast , only a limited range ( @xmath0tenths of a per mil ) of si isotope fractionation has been observed from high - temperature igneous processes .
therefore , si isotopes may be useful as tracers for the presence of crustal material within oib mantle source regions that experienced relatively low - temperature surface processes in a manner similar to other stable isotope systems , such as oxygen .
characterizing the isotopic composition of the mantle is also of central importance to the use of the si isotope system as a basis for comparisons with other planetary bodies ( e.g. , moon , mars , asteroids ) . here
we present the first comprehensive suite of high - precision si isotope data obtained by mc - icp - ms for a diverse suite of oib .
samples originate from ocean islands in the pacific , atlantic , and indian ocean basins and include representative end - members for the em-1 , em-2 , and himu mantle components . on average ,
@xmath1 ^ 30^si values for oib ( @xmath20.32 @xmath3 0.09 , 2 sd ) are in general agreement with previous estimates for the @xmath1 ^ 30^si value of bulk silicate earth ( @xmath20.29 @xmath3 0.07 , 2 sd ; * ? ? ?
* ) .
nonetheless , some small systematic variations are present ; specifically , most himu - type ( mangaia ; cape verde ; la palma , canary islands ) and iceland oib are enriched in the lighter isotopes of si ( @xmath1 ^ 30^si values lower than morb ) , consistent with recycled altered oceanic crust and lithospheric mantle in their mantle sources . .
And you have already written the first three sentences of the full article: knowledge of earth s internal structure and composition has primarily been obtained through complimentary approaches of geophysical and geochemical investigation .
however , debate still persists about the mechanisms responsible for generating the chemical and physical characteristics of earth s mantle observed today , as well as their evolution through time .
the large - scale composition of the mantle may be inferred in part from mantle - derived melts erupted at or near the earth s surface , including mid - ocean ridge basalts ( morb ) and ocean island basalts ( oib ) ..
Please generate the next two sentences of the article | therefore , analyses of oceanic basalts remain a key component in understanding the geochemical complexities of the mantle .
trace element ratios , radiogenic isotope variations ( e.g. , sr , nd , hf , os , pb ) , and noble gas systematics have traditionally been studied in mantle - derived samples to better understand the chemical composition and physical processes occurring within the mantle throughout earth history ( e.g. , * ? ? ? |
4,822 | Suppose that you have an abstract for a scientific paper: we present a proper motion mini - survey of 35 fields in the vicinity of baade window , @xmath0 , sampling roughly a @xmath1 deg region of the galactic bar .
our second epoch observations collected with the acs / hrc instrument on board the hubble space telescope were combined with the archival wfpc2/pc images .
the resulting time baselines are in the range of 48 years
. precise proper motions of 15,863 stars were determined in the reference frame defined by the mean motion of stars with magnitudes between @xmath2 along the line of sight .
we clearly detect small gradients in proper motion dispersions @xmath3 , and in the amount of anisotropy ( @xmath4 ) .
both the longitude dispersion @xmath5 and its ratio to the vertical motion @xmath6 increase toward the galactic plane .
the decline of the anisotropy ratio @xmath7 toward the minor axis of the bulge is mostly due to increasing @xmath6 .
we also find , for the first time , a significant negative covariance term in the transverse velocity field @xmath8 .
our results extend by a factor of @xmath915 the number of the galactic bar fields with good proper motion dispersions .
galactic dynamics - stars : proper motion , dispersion + gravitational lensing - galaxy : bar , bulge , disc .
And you have already written the first three sentences of the full article: the milky way appears to be a typical spiral galaxy with a disk and bulge .
while our unique inside view of the galaxy helps to understand the galactic structure in general , it also makes it more difficult to identify structures such as bars . the case for existence of a bar at the galactic centre first proposed by @xcite is easier to make knowing that bars are common in external galaxies .
there is now conclusive evidence that the galactic bulge is of a barred type ..
Please generate the next two sentences of the article | the longitude asymmetry of the cobe photometric maps ( @xcite ) , high optical depths to gravitational microlensing ( @xcite ) , asymmetric star counts ( @xcite ) , non - circular gas kinematics ( @xcite ) , and triaxiality of the stellar velocity field ( @xcite ) have all been interpreted as signatures of the galactic bar .
unfortunately , the size and precise orientation of the bar are still being debated . |
4,823 | Suppose that you have an abstract for a scientific paper: we extend the fixed center approximation ( fca ) to the faddeev equations for the @xmath0 system with @xmath1 , including the charge exchange mechanisms in the @xmath2 rescattering which have been ignored in former works within the fca .
we obtain similar results to those found before , but the binding is reduced by 6 mev . at the same time we also evaluate the explicit contribution the @xmath3 intermediate state in the three body system and find that it produces and additional small decrease in the binding of about 3 mev .
the system appears bound by about 35 mev and the width omitting two body absorption , is about 50 mev . .
And you have already written the first three sentences of the full article: in this work we present a derivation of the fixed center approximation to the faddeev equations for the @xmath0 system for the case when the @xmath4 system has total spin @xmath1 .
the case for @xmath5 was done in @xcite for @xmath6 at threshold and extended to values below threshold to find a quasibound state in @xcite . an earlier version for @xmath7
was done in @xcite but ignored charge exchange processes in the multiple scattering of the kaons ..
Please generate the next two sentences of the article | the improved results of @xcite for @xmath8 provided a binding of about 12 mev smaller than ignoring the charge exchange processes and was worth being taken into consideration .
the resulting binding was 9 mev with a width of 30 mev . yet , a formula like the one of @xcite for the case of @xmath1 was never derived and one is left with some worry about what could be the effects of charge exchange processes in this latter case . |
4,824 | Suppose that you have an abstract for a scientific paper: we point out a generic inconsistency of the coupling of ordinary gravity as described by general relativity with matter invariant only under unimodular diffeomorphisms ( tdiffs ) , and some previously studied exceptions are pointed out .
the most general lagrangian invariant under tdiff up to dimension five operators is determined , and consistency with existing observations is studied in some cases .
ift - uam / csic-07 - 32 + arxiv : yymm.nnnnvv + * a comment on the matter - graviton coupling * + 0.4 cm _ instituto de fsica terica uam / csic , c - xvi , and departamento de fsica terica , c - xi , + universidad autnoma de madrid e-28049-madrid , spain _ 0.2 cm .
And you have already written the first three sentences of the full article: it is nevertheless clear that given a consistent theory ( such as general relativity itself ) its linear part in any analytic expansion should be consistent as well ( up to linear order )
. the object of our concern in the present paper will be the linear deviations from flat minkowski space , i.e. g_=_+h _ where @xmath3 is the minkowski metric , and @xmath4 .
this equation is taken to be an exact one ; it can be looked at as the definition of @xmath1 ..
Please generate the next two sentences of the article | now , it is a fact of life that @xmath5 has got dimensions of length , and that @xmath6 enjoys dimensions of mass .
the value of newton s constant indicates that at the scale of terrestial experiments , @xmath7 . |
4,825 | Suppose that you have an abstract for a scientific paper: it is known , that an @xmath0-machine is either exactly or asymptotically synchronizing . in the exact case
, the observer can infer the current machine state after observing @xmath1 generated symbols with probability @xmath2 where @xmath3 is a so - called synchronization rate constant . in the asymptotic case
, the probability of the correct prediction the current machine state after observing @xmath1 generated symbols tends to @xmath4 exponentially fast as @xmath5 for @xmath6 and the infimum of such @xmath7 is a so - called prediction rate constant .
hence the synchronization and prediction rate constants serve as natural measures of synchronization for @xmath0-machines . in the present work
we show how to approximate these constants in polynomial time in terms of the number of machine states . .
And you have already written the first three sentences of the full article: a _ deterministic finite automata _ ( dfa ) @xmath8 is a triple @xmath9 where @xmath10 is the state set , @xmath11 is the input alphabet and @xmath12 is the _ transition function_. if @xmath13 is completely defined on @xmath14 then @xmath8 is called _ complete _ , otherwise @xmath8 is called _
partial_. the function @xmath13 extends uniquely to a function @xmath15 , where @xmath16 stands for the free monoid over @xmath11 ; the latter function is still denoted by @xmath13 .
when we have specified a dfa @xmath17 , we can simplify the notation by writing @xmath18 instead of @xmath19 for a subset @xmath20 and a word @xmath21 . in what follows.
Please generate the next two sentences of the article | , we assume @xmath22 because the singleton alphabet case is trivial for considered problems .
given a subset of words @xmath23 and a state @xmath24 denote by @xmath25 the subset of words from @xmath26 labeling some path from @xmath24 in @xmath8 . a dfa @xmath27 is called _ synchronizing _ if there exists a word @xmath28 such that @xmath29 . |
4,826 | Suppose that you have an abstract for a scientific paper: the radiation fields external to the jets and originating from within a few parsecs from the black hole , are discussed in this paper .
they are the direct radiation from an accretion disk in symbiosis with jets , the radiation field from the broad line region ( blr ) surrounding the accretion disk , and the infrared radiation from a dusty torus .
the jet / disk symbiosis modifies the energetics in the central parsec of agn such that for a given accretion rate , a powerful jet would occur at the expense of the disk luminosity , and consequently the disk would less efficiently ionize the brl clouds or heat the dust in the torus , thereby affecting potentially important target photon fields for interactions of gamma - rays , accelerated electrons and protons along the jet .
motivated by unification schemes of active galactic nuclei , we briefly review the evidence for the existence of broad line regions and small - scale dust tori in bl lacs and fanaroff - riley class i ( fr - i ) radio galaxies .
we propose that an existing jet - accretion disk symbiosis can be extrapolated to provide a large scale - symbiosis between other important dusty constituents of the blazar / fr - i family . in the present paper , we discuss in the context of this symbiosis interactions of gev and tev gamma - rays produced in the jet with the various radiation fields external to the jet in quasars and blazars , taking account the anisotropy of the radiation . , submitted + * radiation fields of disk , blr and torus in quasars and blazars : + implications for gamma - ray absorption * + alina - c .
donea and r.j .
protheroe + department of physics and mathematical physics + the university of adelaide , adelaide , sa 5005 , australia * pacs codes : * 98.54.aj quasars 98.54.cm active and peculiar galaxies 98.70.rz gamma - ray sources * keywords : * accretion disk , broad line region , torus , gamma - ray , agn , photon - photon pair production .
And you have already written the first three sentences of the full article: following the introduction of unification schemes for active galactic nuclei ( agn ) , it is now widely accepted that the central nucleus of an active galaxy has a kerr black hole , a relativistic accretion disk , jets , a dusty torus and clouds emitting broad emission lines .
jets and accretion disks are strongly related through a symbiosis , and we postulate that there may also be a large scale symbiosis involving dust components . since @xmath0-rays are attenuated by photon - photon pair production collisions with lower energy photons from the disk , blr , or torus , such a symbiosis could have an effect on the production and absorption of @xmath0-rays in agn as the blr and torus are powered by the disk , and so may depend on the way in which the jets are fed by the accretion disk .
a @xmath0-ray flare could occur , for example , when a significant amount of energy has been accumulated in the inner part of the accretion disk and is subsequently expelled into the jets . as a consequence.
Please generate the next two sentences of the article | , relativistic shocks may form in the jets and could account for the observed rapid and high amplitude @xmath0-ray variability .
the intense emission observed during a flare could be also due to an increase in the accretion rate , in the bulk lorentz factor of the emitting material in the jet , or in the efficiency of particle acceleration . |
4,827 | Suppose that you have an abstract for a scientific paper: transport through molecular magnets is studied in the regime of strong coupling to the leads .
we consider a resonant - tunneling model where the electron spin in a quantum dot or molecule is coupled to an additional local , anisotropic spin via exchange interaction .
the two opposite regimes dominated by resonant tunneling and by kondo transport , respectively , are considered . in the resonant - tunneling regime , the stationary state of the impurity spin
is calculated for arbitrarily strong molecule - lead coupling using a master - equation approach , which treats the exchange interaction perturbatively .
we find that the characteristic fine structure in the differential conductance persists even if the hybridization energy exceeds thermal energies .
transport in the kondo regime is studied within a diagrammatic approach .
we show that magnetic anisotropy gives rise to the appearance of two kondo peaks at nonzero bias voltages . .
And you have already written the first three sentences of the full article: over the past few years the idea of integrating the concepts of spintronics and molecular electronics has developed into a new research field dubbed _
molecular spintronics_.@xcite progress has not only been stimulated by technological interests but has also been accompanied by the realization that magnetic single - molecule transistors exhibit various fundamental quantum phenomena.@xcite among many promising ideas discussed in the literature , particular attention has been paid to current - induced spin reading and writing , spin relaxation , entanglement , quantum computation , and kondo correlations . an experimental realization of spintronics devices may be achieved by using single - molecule magnets in combination with metallic ( nonmagnetic or ferromagnetic ) leads . for molecular - memory applications ,
long spin - relaxation times are advantageous , which may be realized in molecules with large magnetic anisotropy , such as molecules based on @xmath0 , @xmath1 , and @xmath2.@xcite controlling and detecting the molecular spin by means of electronic tunneling into source and drain electrodes poses a major challenge ..
Please generate the next two sentences of the article | while some approaches rely on break junctions , others are based on a scanning tunneling microscope . in both cases ,
the coupling between the molecule and the leads can vary by several orders of magnitude , thus giving rise to strikingly different transport regimes . in the regime of weak molecule - lead coupling , many experimental features such as coulomb blockade |
4,828 | Suppose that you have an abstract for a scientific paper: a celebrated theorem of kirby identifies the set of closed oriented connected 3-manifolds with the set of framed links in @xmath0 modulo two moves . we give a similar description for the set of knots ( and more generally , boundary links ) in homology 3-spheres . as an application
, we define a noncommutative version of the alexander polynomial of a boundary link .
our surgery view of boundary links is a key ingredient in a construction of a rational version of the kontsevich integral , which is described in subsequent work .
stavros .
1991 _ mathematics classification . _ primary 57n10 .
secondary 57m25 . ] .
And you have already written the first three sentences of the full article: surgery ( or cut - and - paste topology ) is a method of modifying a manifold to another one .
surgery was successfully used in the sixties to geometrically realize algebraic invariants of manifolds and leads , for example , to a classification of high dimensional manifolds of a fixed homotopy type .
surgery has also been fruitfully applied to the case of embedding questions , most notably to codimension 2 embeddings , i.e. , knot theory . for an excellent survey ,.
Please generate the next two sentences of the article | see @xcite .
this was pioneered by levine , who used surgery to geometrically realize known knot ( and link ) invariants , such as the alexander polynomial , the alexander module , and well - known concordance invariants of knots , @xcite . |
4,829 | Suppose that you have an abstract for a scientific paper: this article is an expanded version of the talks given by the authors at the arbeitsgemeinschaft `` totally disconnected groups '' , held at oberwolfach in october 2014 .
we recall the basic theory of automorphisms of trees and tits simplicity theorem , and present two constructions of tree groups via local actions with their basic properties : the universal group associated to a finite permutation group by m. burger and s. mozes , and the @xmath0-closures of a given group by c. banks , m. elder and g. willis . .
And you have already written the first three sentences of the full article: in the study of totally disconnected locally compact ( t.d.l.c . ) hausdorff groups , groups of automorphisms of locally finite trees appear naturally and form a significant class of examples .
they are also the most basic case of groups acting on buildings or cat(0 ) cube complexes .
moreover , they play an important role in the structure theory of compactly generated t.d.l.c ..
Please generate the next two sentences of the article | groups through schreier graph constructions ( see @xcite and m. burger s chapter ) . in section 2 ,
we present general results and notions about automorphisms of infinite , locally finite trees . |
4,830 | Suppose that you have an abstract for a scientific paper: polarization profiles are presented for 20 millisecond pulsars that are being observed as part of the parkes pulsar timing array project .
the observations used the parkes multibeam receiver with a central frequency of 1369 mhz and the parkes digital filterbank pulsar signal - processing system pdfb2 .
because of the large total observing time , the summed polarization profiles have very high signal / noise ratios and show many previously undetected profile features .
thirteen of the 20 pulsars show emission over more than half of the pulse period .
polarization variations across the profiles are complex and the observed position angle variations are generally not in accord with the rotating - vector model for pulsar polarization .
never - the - less , the polarization properties are broadly similar to those of normal ( non - millisecond ) pulsars , suggesting that the basic radio emission mechanism is the same in both classes of pulsar .
the results support the idea that radio emission from millisecond pulsars originates high in the pulsar magnetosphere , probably close to the emission regions for high - energy x - ray and gamma - ray emission .
rotation measures were obtained for all 20 pulsars , eight of which had no previously published measurements .
[ firstpage ] pulsars : general polarization radio continuum : stars .
And you have already written the first three sentences of the full article: soon after the discovery of pulsars , it was shown that the radio emission from pulsars is highly polarized @xcite . the mean pulse profile and polarization properties of a pulsar
are important for understanding the pulse emission mechanism , the beaming of pulsar radiation and the geometry of the system .
mean pulse profiles often have a double or triple form , leading to a description of the emission in terms of `` core '' and `` conal '' beams @xcite ..
Please generate the next two sentences of the article | @xcite suggested that the core and conal components had different emission mechanisms whereas @xcite argued that there was a gradual change in emission characteristics from the core region to the outer edge of the emission beam rather than distinct emission processes . to explain more complex pulse profiles , multiple emission cones were proposed and discussed by several authors @xcite .
an alternative model suggests that the emission beam of a pulsar is filled with randomly distributed emission patches @xcite . |
4,831 | Suppose that you have an abstract for a scientific paper: in a recent publication [ galanakis i et al 2006 b * 74 * 140408(r ) ] we have shown that in the case of cras and related transition - metal chalcogenides and pnictides , crystallizing in the zinc - blende structure , the excess of the transition - metal atoms leads to half - metallic ferrimagnetism .
the latter property is crucial for spintronic applications with respect to ferromagnets due to the lower stray fields created by these materials .
we extend this study to cover the case where the transition - metal atoms sitting at antisites are not identical to the ones in the perfect sites . in cr - based compounds
, the creation of mn antisites keeps the half - metallic ferrimagnetic character produced also by the cr antisites . in the case of vas , cr and mn antisites keep the half - metallic character of vas ( contrary to v antisites ) due to the larger exchange - splitting exhibited by these atoms . .
And you have already written the first three sentences of the full article: the rapid emergence of the field of spintronics ( also known as magnetoelectronics @xcite ) brought to the center of scientific research the so - called half - metallic ferromagnets ( like heusler alloys @xcite or some oxides @xcite ) .
these compounds present metallic behavior for one spin - band while they are semiconducting or insulators for the other spin - band , resulting to perfect spin - polarization , at least for the bulk , at the fermi level . for realistic application ferromagnets create large stray fields and thus lead to considerable undesirable energy losses .
thus , to this respect the case of half - metallic ferrimagnets is more interesting ..
Please generate the next two sentences of the article | there are several ways to create a half - metallic ferrimagnet , either by doping a semiconductor like fevsb @xcite or due to the simultaneous presence of mn and another transition - metal atom in the case of alloys with small total moment due to the small number of valence electrons ( e.g. femnsb @xcite or mn@xmath0val @xcite ) .
recently akai and ogura have proposed another route to fully - compensated half - metallic ferrimagnetism based on the doping of diluted magnetic semiconductors @xcite . except heusler and oxides , also transition - metal chalcogenides like cras and pnictides like crse |
4,832 | Suppose that you have an abstract for a scientific paper: we study the production of @xmath0 in @xmath1 annihilation through two virtual photons .
the cross section is estimated to be 23 fb at @xmath2 gev , which is smaller by a factor of six than the calculated cross section for the same process but through one virtual photon . as a result , while the annihilation into two photons may be important for certain exclusive production processes , the big gap between the inclusive production cross section @xmath3 0.9pb observed by belle and the current nonrelativistic qcd prediction of @xmath40.15pb still remains very puzzling .
we find , however , as the center - of - mass energy increases ( @xmath5 gev ) the production through two virtual photons @xmath6 will prevail over that through one virtual photon , because in the former process the photon fragmentation into @xmath7 and into the charmed quark pair becomes more important at higher energies .
+ pacs number(s ) : 12.40.nn , 13.85.ni , 14.40.gx production of @xmath8 through two photons in @xmath1 annihilation + kui - yong liu and zhi - guo he + department of physics , peking university , beijing 100871 , people s republic of china + kuang - ta chao + china center of advanced science and technology ( world laboratory ) , beijing 100080 , people s republic of china and department of physics , peking university , beijing 100871 , people s republic of china charmonium production is one of the important processes to test quantum chromodynamics ( qcd ) both perturbatively and non - perturbatively .
because of the simpler parton structure involved , which will reduce the theoretical uncertainty , charmonium production in @xmath1 annihilation is expected to be more decisive in clarifying the production mechanisms of heavy quarkonia .
the two b factories with babar and belle are collecting huge data samples of continuum @xmath1 annihilation events , which will allow us to have a fine data analysis for charmonium production .
recently , charmonium production in @xmath1 annihilation has become more....
And you have already written the first three sentences of the full article: this work was supported in part by the national natural science foundation of china , and the education ministry of china .
k@xmath71hn , j. kaplan and e.g.o .
safiani , nucl . phys . *.
Please generate the next two sentences of the article | b157 * , 125 ( 1979 ) ; b. guberina , j.h .
k@xmath72hn , r.d . |
4,833 | Suppose that you have an abstract for a scientific paper: we study , using general scaling arguments and mean - field type calculations , the behavior of the critical casimir force and its interplay with the van der waals force acting between two parallel slabs separated at a distance @xmath0 from each other , confining some fluctuating fluid medium , say a non - polar one - component fluid or a binary liquid mixture .
the surfaces of the slabs are coated by thin layers exerting strong preference to the liquid phase of the fluid , or one of the components of the mixture , modeled by strong adsorbing local surface potentials ensuring the so - called @xmath1 boundary conditions .
the slabs , on the other hand , influence the fluid by long - range competing dispersion potentials , which represent irrelevant interactions in renormalization group sense . under such conditions
one usually expects _ attractive _ casimir force governed by universal scaling function , pertinent to the extraordinary surface universality class of ising type systems , to which the dispersion potentials provide only corrections to scaling .
we demonstrate , however , that below a given threshold thickness of the system @xmath2 for a suitable set of slabs - fluid and fluid - fluid coupling parameters the competition between the effects due to the coatings and the slabs can result in _ sign change _ of the casimir force acting between the surfaces confining the fluid when one changes the temperature @xmath3 , the chemical potential of the fluid @xmath4 , or @xmath0 .
the last implies that by choosing specific materials for the slabs , coatings and the fluid for @xmath5 one can realize _ repulsive _ casimir force with _ non - universal _ behavior which , upon increasing @xmath0 , gradually turns into an _ attractive _ one described by an _
universal _ scaling function , depending only on the relevant scaling fields related to the temperature and the excess chemical potential , for @xmath6 .
we presented arguments and relevant data for specific substances in support of the....
And you have already written the first three sentences of the full article: when a fluctuating field is confined by material bodies , effective forces arise on them . this is due to the fact that the bodies impose boundary conditions on the medium , depending on their geometry , mutual position and material properties , which leads to a modification of the allowed fluctuations in the medium .
the last leads to a dependence of the ground state , or the thermodynamic potential of the system ( say the free energy ) on the geometry of the system and on the distances between its ( macroscopic ) components . in order to change these distances
one has to apply a force that depends on the induced change of the allowed fluctuations ..
Please generate the next two sentences of the article | if the fluctuations are long - ranged the corresponding forces are also long - ranged .
the existence of such long - ranged fluctuation mediated forces is called the casimir effect and the corresponding forces |
4,834 | Suppose that you have an abstract for a scientific paper: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ many np - hard winner determination problems admit polynomial - time algorithms....
And you have already written the first three sentences of the full article: in a departure from classical voting theory , a growing literature from computational social choice has recently studied _ multi - winner _ voting rules : given diverse preferences of a collection of agents , instead of identifying a single best alternative , we are aiming for a ( fixed - size ) _ set _ of alternatives that jointly are able to represent the preferences of the agents best .
such procedures are useful in a wide variety of circumstances : obvious examples include the election of a parliament , or of a committee representing the interests of members of an organisation .
other applications can be found in group recommendation systems , or for making decisions about which products or services to offer : which courses should be offered at a university ? which movies should be presented on an airline entertainment system ? several attractive rules for such tasks have been designed by researchers in political science ( e.g. , @xcite @xcite , @xcite @xcite ) and more recently by computer scientists @xcite ..
Please generate the next two sentences of the article | many of these rules are defined in terms of some objective function : a winning committee is a set of @xmath0 candidates that maximises this objective .
unsurprisingly , then , the winner determination problems of such rules are typically np - hard @xcite . to tackle the complexity of these problems , approximation algorithms @xcite and fixed - parameter tractability approaches @xcite have been developed for these problems , and integer programming formulations |
4,835 | Suppose that you have an abstract for a scientific paper: the colored jones polynomial of links has two natural normalizations : one in which the @xmath0-colored unknot evaluates to @xmath1,$ ] the quantum dimension of the @xmath2-dimensional irreducible representation of quantum @xmath3 and the other in which it evaluates to @xmath4 for each normalization we construct a bigraded cohomology theory of links with the colored jones polynomial as the euler characteristic .
_ _ # 1#2#3#4 \
{ ll # 1 & # 2 + # 3 & # 4 .
# 1#2 ( c # 1 + # 2 ) # 1 .
And you have already written the first three sentences of the full article: * the jones polynomial . *
the jones polynomial @xmath5 of an oriented link @xmath6 in @xmath7 is determined by the skein relation @xmath8 for any three links @xmath9 that differ as shown in figure [ skein ] , and its value on the unknot , which we choose to be @xmath10 [ htb ] the jones polynomial does not depend on the framing of link components , but depends slightly on their orientations . reversing the orientation of a component @xmath11 multiplies the polynomial by @xmath12 where @xmath13 is the linking number of @xmath14 with its complement in @xmath15 * the colored jones polynomial .
* we briefly recall the basics about the colored jones polynomial of links ( for more details consult @xcite , @xcite , ( * ? ? ?.
Please generate the next two sentences of the article | * sections 3,4 ) , and references therein ) . given an oriented framed link @xmath6 whose
components are colored ( marked ) by non - negative integers ( or , equivalently , by irreducible representations of @xmath16 with integer @xmath0 corresponding to the @xmath2-dimensional representation @xmath17 ) , the colored jones polynomial @xmath18 takes values in @xmath19.$ ] the label @xmath20 stands for the coloring , that is , for a function from the set of components of @xmath6 to non - negative integers . |
4,836 | Suppose that you have an abstract for a scientific paper: we present the analysis of high angular resolution observations of the triple asteroid ( 87 ) sylvia collected with three 810 m class telescopes ( keck , vlt , gemini north ) and the hubble space telescope .
the moons mutual orbits were derived individually using a purely keplerian model .
we computed the position of romulus , the outer moon of the system , at the epoch of a recent stellar occultation which was successfully observed at less than 15 km from our predicted position , within the uncertainty of our model .
the occultation data revealed that the moon , with a surface - area equivalent diameter @xmath0 km , is strongly elongated ( axes ratio of @xmath1 ) , significantly more than single asteroids of similar size in the main - belt .
we concluded that its shape is probably affected by the tides from the primary .
a new shape model of the primary was calculated combining adaptive - optics observations with this occultation and 40 archived light - curves recorded since 1978 .
the difference between the @xmath2 derived from the 3-d shape model assuming an homogeneous distribution of mass for the volume equivalent diameter @xmath3= @xmath4 km primary and the null @xmath5 implied by the keplerian orbits suggests a non - homogeneous mass distribution in the asteroid s interior .
asteroids , satellites of asteroids , adaptive optics , photometry , orbit determination , occultations .
And you have already written the first three sentences of the full article: the minor planet ( 87 ) sylvia is a main belt asteroid discovered in 1866 by @xcite . in the 1990s ,
frequency analysis of photometric observations hinted that this asteroid could be binary @xcite .
its first satellite ( s/2001 ( 87 ) 1 , known as _ romulus _ ) was discovered in february 2001 by @xcite using the keck ii telescope atop hawaii s mauna kea ..
Please generate the next two sentences of the article | three years later , @xcite announced the discovery of a second companion ( s/2004 ( 87 ) 1 , known as _ remus _ ) , using the european southern observatory s very large telescope ( vlt ) .
sylvia became the first known triple asteroidal system . |
4,837 | Suppose that you have an abstract for a scientific paper: we present results of our study of pds 11 binary system , which belongs to a rare class of isolated , high galactic latitude t tauri stars .
our spectroscopic analysis reveals that pds 11 is a m2@xmath0m2 binary system with both components showing similar h@xmath1 emission strength .
both the components appear to be accreting , and are classical t tauri stars .
the lithium doublet lii @xmath26708 , a signature of youth , is present in the spectrum of pds 11a , but not in pds 11b . from the application of lithium depletion boundary age - dating method and a comparison with the lii @xmath26708 equivalent width distribution of moving groups , we estimated an age of 10@xmath015 myr for pds 11a .
comparison with pre - main sequence evolutionary models indicates that pds 11a is a 0.4 m@xmath3 t tauri star at a distance of 114@xmath0131 pc .
pds 11 system does not appear to be associated with any known star forming regions or moving groups .
pds 11 is a new addition , after twa 30 and lds 5606 , to the interesting class of old , dusty , wide binary classical t tauri systems in which both components are actively accreting . .
And you have already written the first three sentences of the full article: t tauri stars are low - mass ( k & m spectral types ) young stars which are in their pre - main sequence phase of evolution ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | they are often associated with cloud complexes such as taurus , orion and ophiuchus @xcite . however
, t tauri stars are also found in isolated regions above the galactic plane and far from any dark clouds @xcite . |
4,838 | Suppose that you have an abstract for a scientific paper: we study the scalar , conformally invariant wave equation on a four - dimensional minkowski background in spherical symmetry , using a fully pseudospectral numerical scheme .
thereby , our main interest is in a suitable treatment of spatial infinity , which is represented as a cylinder .
we consider both cauchy problems , where we evolve data from a cauchy surface to future null infinity , as well as characteristic initial value problems with data at past null infinity , and demonstrate that highly accurate numerical solutions can be obtained for a small number of grid points . .
And you have already written the first three sentences of the full article: the _ global _ treatment of asymptotically flat ( or , more generally , asymptotically simple ) spacetimes as models for isolated systems is an important topic , both in mathematical and in numerical relativity .
in particular , this is relevant for a rigorous investigation of gravitational wave signals , which can be uniquely read off only at null infinity @xmath0 .
indeed , it has been shown that certain tail decay rates at timelike boundaries ( which are often introduced as `` artificial '' outer boundaries for numerical computations ) and at null infinity are different , so that an appropriate treatment of infinity is crucial , see , e.g. , @xcite and references therein ..
Please generate the next two sentences of the article | an important ingredient for such a rigorous treatment is penrose s conformal boundary @xcite , which is obtained by isometrically embedding the spacetimes into larger lorentzian manifolds and conformally rescaling the metric , i.e. the `` physical '' metric is replaced by a conformal metric and a conformal factor . a formulation of einstein s field equations adapted to this setting , the conformal field equations ( cfe ) , was given by friedrich @xcite . in the context of this approach , it is well - known that certain mathematical difficulties arise in the region near spacelike infinity @xmath1 . in order to cope with this problem ,
friedrich has introduced yet another formulation of the field equations , the generalised cfe @xcite . moreover , |
4,839 | Suppose that you have an abstract for a scientific paper: the problem of a random walk on a finite triangular lattice with a single interior source point and zig - zag absorbing boundaries is solved exactly .
this problem has been previously considered intractable .
# 1 epsf.sty .
And you have already written the first three sentences of the full article: the problem of a random walk on a two - dimensional lattice with a single interior source point and absorbing boundaries was first considered by courant _
_ @xcite in 1928 where general properties of the solution were discussed .
this problem was solved exactly in 1940 @xcite for the case of random walks on a square lattice with rectangular absorbing boundaries ..
Please generate the next two sentences of the article | the problem on a triangular lattice with finite absorbing boundaries was considered in 1963 @xcite where the exact solution was given for an approximation of the problem using straight boundaries rather than the true zig - zag boundaries of the triangular lattice .
indeed the authors of this paper remarked that `` an explicit solution of the difference equation can hardly be obtained if these boundary conditions are used . '' other variants of the problem on the square lattice have been solved exactly @xcite however the problem on the triangular lattice with true zig - zag triangular lattice boundaries has remained unsolved . in this paper |
4,840 | Suppose that you have an abstract for a scientific paper: we describe the statistical properties of narrowband drifting auroral kilometric radiation ( striated akr ) based on observations from the cluster wideband receiver during 2002 - 2005 .
we show that the observed characteristics , including frequency drift rate and direction , narrow bandwidth , observed intensity , and beaming angular sizes are all consistent with triggering by upward traveling ion solitary structures ( ` ion holes ' ) .
we calculate the expected perturbation of a horseshoe electron distribution function by an ion hole by integrating the resonance condition for a cyclotron maser instability ( cmi ) using the perturbed velocity distribution .
we find that the cmi growth rate can be strongly enhanced as the horseshoe velocity distribution contracts inside the passing ion hole , resulting in a power gain increase greater than 100 db .
the gain curve is sharply peaked just above the r - mode cut - off frequency , with an effective bandwidth @xmath050 hz , consistent with the observed bandwidth of striated akr emission .
ion holes are observed _ in situ _ in the acceleration region moving upward with spatial scales and speeds consistent with the observed bandwidth and slopes of sakr bursts .
hence , we suggest that sakr bursts are a remote sensor of ion holes and can be used to determine the frequency of occurrence , locations in the acceleration region , and lifetimes of these structures . .
And you have already written the first three sentences of the full article: auroral kilometric radiation ( akr ) bursts exhibit a wide variety of fine structure as seen on frequency - time spectra .
the cyclotron maser instability ( cmi ) @xcite is widely assumed to be the basic plasma mechanism responsible for the emission .
this mechanism originally assumed a loss - cone electron velocity distribution function , but in situ observations in the acceleration region have shown that a horseshoe or crescent distribution is more accurate @xcite ..
Please generate the next two sentences of the article | the horseshoe distribution , which arises naturally for electron beams in the presence of inhomogeneous magnetic fields @xcite , provides a robust and efficient free energy source for the cmi mechanism , as shown both by model calculations ( e.g. * ? ? ?
* ; * ? ? ? |
4,841 | Suppose that you have an abstract for a scientific paper: we present a model for dilepton production of proton - proton collisions using a realist @xmath0-matrix that by incorporating @xmath1 degrees of freedom fits the @xmath2 scattering data up to 2 gev .
the results we find differ in details from earlier work that use less sophisticated interactions but the overall agreement with these calculations is good . .
And you have already written the first three sentences of the full article: recently various scenarios related to in - medium modifications of the properties of the @xmath3-meson have been proposed @xcite to explain the apparent increase in the production of dilepton pairs with an invariant mass around the @xmath3 meson in heavy ion collisions @xcite . to really be able to extract these signals , possibly due to a decrease in the @xmath3 mass as a result of chiral symmetry restoration
, the description of the fundamental processes has to be on a firm ground and its inherent approximations have to be well understood . in this paper
we will investigate the elementary process of dilepton pair production off nucleon - nucleon collisions ..
Please generate the next two sentences of the article | two ingredients are of importance here .
first there is the question of the nucleon - nucleon form factor . |
4,842 | Suppose that you have an abstract for a scientific paper: a sensor network is a collection of wireless devices that are able to monitor physical or environmental conditions . these devices ( nodes )
are expected to operate autonomously , be battery powered and have very limited computational capabilities .
this makes the task of protecting a sensor network against misbehavior or possible malfunction a challenging problem . in this document
we discuss performance of artificial immune systems ( ais ) when used as the mechanism for detecting misbehavior .
we show that ( i ) mechanism of the ais have to be carefully applied in order to avoid security weaknesses , ( ii ) the choice of genes and their interaction have a profound influence on the performance of the ais , ( iii ) randomly created detectors do not comply with limitations imposed by communications protocols and ( iv ) the data traffic pattern seems not to impact significantly the overall performance .
we identified a specific mac layer based gene that showed to be especially useful for detection ; genes measure a network s performance from a node s viewpoint .
furthermore , we identified an interesting complementarity property of genes ; this property exploits the local nature of sensor networks and moves the burden of excessive communication from normally behaving nodes to misbehaving nodes .
these results have a direct impact on the design of ais for sensor networks and on engineering of sensor networks .
= 1.0 sensor networks , ad hoc wireless networks , artificial immune systems , misbehavior . .
And you have already written the first three sentences of the full article: sensor networks @xcite can be described as a collection of wireless devices with limited computational abilities which are , due to their ad - hoc communication manner , vulnerable to misbehavior and malfunction .
it is therefore necessary to support them with a simple , _ computationally friendly _ protection system . due to the limitations of sensor networks
, there has been an on - going interest in providing them with a protection solution that would fulfill several basic criteria ..
Please generate the next two sentences of the article | the first criterion is the ability of self - learning and self - tuning .
because maintenance of ad hoc networks by a human operator is expected to be sporadic , they have to have a built - in _ autonomous _ |
4,843 | Suppose that you have an abstract for a scientific paper: we examine the collapse of an axion domain wall bounded by an axionic string . it is found that the collapse proceeds quickly and axion
domain walls disappear
. however axions are emitted in the collapse and its energy density increases during radiation dominated era and contributes significantly to the present mass density of the universe . in particular
the axion emitted from the wall can account for the dark matter in the universe for @xmath0 . .
And you have already written the first three sentences of the full article: the axion@xcite is the nambu - goldstone boson associated with the peccei - quinn symmetry breaking which was invented as the most natural solution to the strong cp problem@xcite of qcd .
the peccei - quinn symmetry breaking scale @xmath1 is stringently constrained by the consideration of accelerator experiments , stellar cooling and cosmology .
the allowed range of @xmath2 ( axion window ) is between @xmath3 and @xmath4 , where the integer @xmath5 is the color anomaly of peccei - quinn symmetry . since the peccei - quinn symmetry is a global u(1 ) symmetry , global strings ( axionic strings ).
Please generate the next two sentences of the article | are produced during spontaneous symmetry breaking . at this stage
the potential for the axion field is flat , i.e. , the axion is massless . |
4,844 | Suppose that you have an abstract for a scientific paper: using scanning tunneling microscopy ( stm ) in ultra high vacuum and atomic force microscopy , we investigate the corrugation of graphene flakes deposited by exfoliation on a si / sio@xmath0 ( 300 nm ) surface . while the corrugation on sio@xmath0 is long - range with a correlation length of about 25 nm , some of the graphene monolayers exhibit an additional corrugation with a preferential wave length of about 15 nm .
a detailed analysis shows that the long range corrugation of the substrate is also visible on graphene , but with a reduced amplitude , leading to the conclusion that the graphene is partly freely suspended between hills of the substrate .
thus , the intrinsic rippling observed previously on artificially suspended graphene can exist as well , if graphene is deposited on sio@xmath0 .
since it was believed , based on the mermin - wagner theorem , that two - dimensional ( 2d ) crystals are not stable at finite temperature @xcite , it came as a surprise that monolayer graphene could be stabilized on a si / sio@xmath0 substrate @xcite .
due to its peculiar properties like , e.g. , a linear dispersion leading to klein tunneling @xcite , high room - temperature mobility allowing quantum hall steps at 300 k @xcite , a low spin - orbit interaction beneficial for spintronic devices @xcite or tunable spin - polarized edge states @xcite , graphene studies have become a major issue in solid - state physics .
already the first transport results not exhibiting weak localization lead to the speculation of a curved surface @xcite acting as a phase - breaking field @xcite .
such a curvature was indeed observed by microscopic electron diffraction of suspended monolayer graphene sheets @xcite .
the lateral wavelength of the isotropic curvature is estimated to be @xmath1 nm with an amplitude of @xmath2 nm .
the rippling has been reproduced theoretically by monte - carlo simulations with a preferential wavelength of 8 nm barely depending on temperature @xcite .
it is argued that the....
And you have already written the first three sentences of the full article: figure [ figs1 ] shows representative histograms of the height values on the sio@xmath0 substrate and the graphene sample as obtained by atomic force microscopy ( afm ) and scanning tunneling microscopy ( stm ) , respectively .
the histograms are based on images of 200 @xmath24 200 nm@xmath7 including 512 @xmath24 512 measurement points each .
these images are shown in fig ..
Please generate the next two sentences of the article | 3 of the main text .
the histogram curves are normalized in order to enclose the same integral area . |
4,845 | Suppose that you have an abstract for a scientific paper: we present measurements by the phenix experiment at rhic of di - hadron pair production in @xmath0aucollisions where the particles in the pair are varied across a wide range of pseudorapidity , out to @xmath1 . with di - hadrons
, varying the @xmath2 and rapidity of the particles in the di - hadron pair allows studying any effects as a function of partonic @xmath3 in the nucleus .
these di - hadron measurements might probe down to parton momentum fractions x @xmath4 @xmath5 in the gold nucleus , where the interesting possibility of observing gluon saturation effects at rhic is the greatest .
our measurements show that the correlated yield of back - to - back pairs in @xmath0aucollisions is suppressed by up to an order of magnitude relative to @xmath6+@xmath6collisions , and increases with greater nuclear path thickness and with a selection for lower x in the au nucleus . .
And you have already written the first three sentences of the full article: deuteron - gold collisions at rhic provide a means to explore nuclear effects on the initial - state parton densities in the nucleus , which is vitally important for understanding the baseline production in heavy - ion collisions .
rhic experiments have shown that single inclusive hadron yields in the forward ( deuteron ) rapidity direction for @xmath7 gev @xmath0aucollisions are suppressed relative to @xmath6+@xmath6collisions @xcite .
the mechanism for the suppression has not been firmly established ..
Please generate the next two sentences of the article | many effects have been proposed for this suppression , such as gluon saturation @xcite , initial state energy loss @xcite , parton recombination @xcite , multi - parton interactions @xcite , and leading and higher - twist shadowing @xcite .
one set of measurements that might help to distinguish between the competing models is forward azimuthally correlated di - hadron correlation functions , which directly probe di - jet production through their 2@xmath82 back - to - back peak at @xmath9 . |
4,846 | Suppose that you have an abstract for a scientific paper: we consider the energy spectrum and the spin - parity structure of the eigenstates for a quantum dot made of a strong topological insulator .
using the effective low - energy theory in a finite - length cylinder geometry , numerical calculations show that even at the lowest energy scales , the spin direction in a topologically protected surface mode is not locked to the surface .
we find `` zero - momentum '' modes , and subgap states localized near the `` caps '' of the dot .
both the energy spectrum and the spin texture of the eigenstates are basically reproduced from an analytical surface dirac fermion description .
our results are compared to microscopic calculations using a tight - binding model for a strong topological insulator in a finite - length nanowire geometry . .
And you have already written the first three sentences of the full article: the theoretical prediction and subsequent experimental verification of the conducting surface state of a strong topological insulator ( ti ) continues to generate a lot of excitement in physics ; for reviews , see refs . .
in a ti , strong spin - orbit couplings and band inversion conspire to produce a time - reversal invariant topological state different from a conventional band insulator . using bi@xmath0se@xmath1 as a weakly correlated reference ti material with rather large bulk gap @xmath2 mev ,
surface probe experiments have provided strong evidence for the topologically protected gapless surface state.@xcite the measured spin texture of the surface state is consistent with predictions obtained for two - dimensional ( 2d ) massless dirac fermions . under this `` relativistic '' description ,.
Please generate the next two sentences of the article | the spin direction is locked to the surface , and the surface state is stable against the effects of weak disorder and weak interactions ( topological protection).@xcite it is thus useful to first study the simplest case of a noninteracting disorder - free model , which is the case investigated below . because of the residual bulk conductivity of the presently available ( nominally insulating ) ti samples , it has been difficult to experimentally extract the surface contribution to the electrical conductivity .
one attempt to improve the situation is to consider mesoscopic samples , where the surface - to - volume ratio is more advantageous . in particular , thin - film geometries@xcite and quasi-1d nanowires ( `` ribbons'')@xcite have been studied experimentally . |
4,847 | Suppose that you have an abstract for a scientific paper: the phase separation process which follows a sudden quench inside the coexistence region is considered for a binary fluid subjected to an applied shear flow .
this issue is studied in the framework of the convection - diffusion equation based on a ginzburg - landau free energy functional in the approximation scheme introduced by bray and humayun [ _ phys.rev.lett . _ * 68 * , 1559 , ( 1992 ) ] .
after an early stage where domains form and shear effects become effective the system enters a scaling regime where the typical domains sizes @xmath0 , @xmath1 along the flow and perpendicular to it grow as @xmath2 and @xmath3 .
the structure factor is characterized by the existence of four peaks , similarly to previous theoretical and experimental observations , and by exponential tails at large wavevectors . #
1#2 # # 1##2#2##1 .
And you have already written the first three sentences of the full article: the process of phase - separation occurring in binary systems quenched below the coexistence line has been matter of intensive investigations since many years .
the overall phenomenology is nowadays reasonably well understood . in an early stage ,
whose properties depend on the system specific details , domains of the two phases form ; the relative concentration of the two species well inside the domains quickly saturates to a value very similar to the equilibrium composition ..
Please generate the next two sentences of the article | then a crossover leads to the late stage dynamics which is characterized by the growth of ordered regions of typical size @xmath4 and by a statistically invariant morphology .
this phenomenology is at the basis of the well known scaling property according to which a single length @xmath4 is asymptotically relevant : system configurations at different times are simply related by a scale transformation with a scale factor @xmath4 . in particular , for the equal time density - density correlation function one has g(r , t)=g , [ sca ] meaning precisely that @xmath5 is invariant as a function of scaled lengths @xmath6 . |
4,848 | Suppose that you have an abstract for a scientific paper: the random numbers driving markov chain monte carlo ( mcmc ) simulation are usually modeled as independent @xmath0 random variables .
tribble [ markov chain monte carlo algorithms using completely uniformly distributed driving sequences ( 2007 ) stanford univ . ]
reports substantial improvements when those random numbers are replaced by carefully balanced inputs from completely uniformly distributed sequences . the previous theoretical justification for using anything other than i.i.d .
@xmath0 points shows consistency for estimated means , but only applies for discrete stationary distributions .
we extend those results to some mcmc algorithms for continuous stationary distributions .
the main motivation is the search for quasi - monte carlo versions of mcmc . as a side benefit ,
the results also establish consistency for the usual method of using pseudo - random numbers in place of random ones . , and . .
And you have already written the first three sentences of the full article: in markov chain monte carlo ( mcmc ) , one simulates a markov chain and uses sample averages to estimate corresponding means of the stationary distribution of the chain .
mcmc has become a staple tool in the physical sciences and in bayesian statistics . when sampling the markov chain , the transitions are driven by a stream of independent @xmath0 random numbers .
in this paper , we study what happens when the i.i.d ..
Please generate the next two sentences of the article | @xmath0 random numbers are replaced by deterministic sequences , or by some dependent @xmath0 values . the motivation for replacing i.i.d .
@xmath0 points is that carefully stratified inputs may lead to more accurate sample averages . |
4,849 | Suppose that you have an abstract for a scientific paper: using our photoionization code cirrus @xcite , we show that the study of proximity effect on metal elements provides a possibility of placing constraints on the spectral shape of the metagalactic uv background ( muvb ) . from theoretical point of view , the most optimum indicator of the spectral shape of the muvb is the ratio o iv / o iii . unlike previous thought ,
the ratio si iv / c iv is not a good indicator of the spectral shape because of its strong dependence on an ionization parameter as well .
we also find that the observed excess of c iv systems in luminous qsos may be a photoionization effect , but not a gravitational lensing effect @xcite . .
And you have already written the first three sentences of the full article: the h i proximity effect has been widely studied since it was discovered .
one thing of particular interest is that the study of the h i proximity effect provides a method of measuring the intensity of the muvb at the h i edge .
however , the h i proximity effect does not reveal information on the spectral shape of the muvb ..
Please generate the next two sentences of the article | we demonstrate that the proximity effect on metal elements may provide a method for constraining the spectral shape of the muvb .
songalia and cowie ( 1996 ) @xcite reported that metal elements are detected in 75% of clouds with @xmath0 . |
4,850 | Suppose that you have an abstract for a scientific paper: we develop a qualitative geometric approach to swimming at low reynolds number which avoids solving differential equations and uses instead landscape figures of two notions of curvatures : the swimming curvature and the curvature derived from dissipation .
this approach gives complete information for swimmers that swim on a line without rotations and gives the main qualitative features for general swimmers that can also rotate .
we illustrate this approach for a symmetric version of purcell s swimmer which we solve by elementary analytical means within slender body theory .
we then apply the theory to derive the basic qualitative properties of purcell s swimmer . .
And you have already written the first three sentences of the full article: micro - swimmers are of general interest lately , motivated by both engineering and biological problems @xcite
. they can be remarkably subtle as was illustrated by e. m. purcell in his famous talk on life at low reynolds numbers " @xcite where he introduced a deceptively simple swimmer shown in fig .
[ fig : purcell ] ..
Please generate the next two sentences of the article | purcell asked `` what will determine the direction this swimmer will swim ? ''
this simple looking question took 15 years to answer : koehler , becker and stone @xcite found that the direction of swimming depends , among other things , on the stroke s _ amplitude _ : increasing the amplitudes of certain small strokes that propagate the swimmer to the right result in propagation to the left . |
4,851 | Suppose that you have an abstract for a scientific paper: we present the results of axisymmetric time - dependent hydrodynamic calculations of line - driven winds from accretion disks in active galactic nuclei ( agn ) .
we assume the disk is flat , keplerian , geometrically thin , and optically thick , radiating according to the @xmath0-disk prescription .
the central engine of the agn is a source of both ionizing x - rays and wind - driving ultraviolet ( uv ) photons . to calculate the radiation force , we take into account radiation from the disk and the central engine .
the gas temperature and ionization state in the wind are calculated self - consistently from the photoionization and heating rate of the central engine .
we find that a disk accreting onto a @xmath1 black hole at the rate of @xmath2 can launch a wind at @xmath3 cm from the central engine .
the x - rays from the central object are significantly attenuated by the disk atmosphere so they can not prevent the local disk radiation from pushing matter away from the disk .
however in the supersonic portion of the flow high above the disk , the x - rays can overionize the gas and decrease the wind terminal velocity . for a reasonable x - ray opacity , e.g. , @xmath4 ,
the disk wind can be accelerated by the central uv radiation to velocities of up to 15000 @xmath5 at a distance of @xmath6 cm from the central engine .
the covering factor of the disk wind is @xmath7 .
the wind is unsteady and consists of an opaque , slow vertical flow near the disk that is bounded on the polar side by a high - velocity stream .
a typical column density through the fast stream is a few @xmath8 so the stream is optically thin to the uv radiation .
this low column density is precisely why gas can be accelerated to high velocities .
the fast stream contributes nearly 100% to the total wind mass loss rate of @xmath9 .
= = = 1=1=0pt = 2=2=0pt .
And you have already written the first three sentences of the full article: many observed spectral features of active galactic nuclei ( agn ) indicate that outflows are common in these systems . the prominent broad emission lines ( bel ) in ultraviolet ( uv ) from h
i , o vi , n v , c iv , and si iv are the defining feature of quasars ( blandford , netzer & woltjer 1990 ; osterbrock 1989 ) , and they may be associated with a high velocity outflow .
fast outflows can also explain narrow uv absorption lines from highly ionized species such as c iv and n v observed in approximately half of the hst - observed seyfert 1 galaxies ( e.g. , crenshaw 1997 ) ..
Please generate the next two sentences of the article | these narrow absorption lines are all blueshifted relative to the systemic velocity by 0 to -1600 km s@xmath10 .
recent asca observations show that in a small sample observed by hst and asca , all of the seyfert galaxies with warm absorbers also show intrinsic uv absorption . |
4,852 | Suppose that you have an abstract for a scientific paper: we construct a new kinematical variable that is able to fully reconstruct the absolute value , and partially reconstruct the sign , of the angular distribution in the center of momentum system of a decaying particle in certain cases where the center of momentum system is only known up to a two - fold ambiguity . after making contact with drell - yan production at the large hadron collider , we apply this method to the pair - production of dark matter in association with two charged leptons at the international linear collider and show that for a small intermediate width , perfect agreement is found with the true angular distribution in the absence of initial state radiation . in the presence of initial state radiation , we find that the modification to the angular distributions is small for most angles and that different spin combination classes should still be distinguishable .
this enables us to determine the spin of the mother particle and the dark matter particle in certain cases .
the existence of dark matter has been well established through a combination of galactic rotation curves @xcite , weak and strong gravitational lensing @xcite , big bang nucleosynthesis @xcite , the cosmic microwave background @xcite and the bullet cluster @xcite . from these observations ,
we know that dark matter is electrically neutral , non - baryonic and composes roughly 83% of the matter and 23% of the energy of the universe .
however , these observations do not tell us the detailed properties of dark matter such as its mass , spin and how it interacts with visible matter . for that , we need to observe a dark matter particle ( dmp ) in the laboratory . because the standard model ( sm ) of particle physics does not contain dark - matter ( among other things ) it is a low - energy effective theory that fits inside a larger , more complete theory .
two prominent examples of these theories are the minimal supersymmetric extension of the sm ( mssm ) and the universal extra - dimension ( ued ) model . in the....
And you have already written the first three sentences of the full article: in this section , we summarize the derivation of eqs . through .
we consider an on - shell particle @xmath2 which decays to the particles @xmath1 and @xmath7 , both of which are on - shell ( see fig . [
fig : bldsystem ] ) ..
Please generate the next two sentences of the article | we assume the masses of these particles are known and are @xmath9 , @xmath10 and @xmath11 , respectively .
we boost into the @xmath2 cm frame and calculate the cosine of the angle of @xmath1 with respect to the boost direction , which is given by @xmath22 where the subscript @xmath23 refers to the @xmath2 cm frame . for convenience , and without loss of generality , |
4,853 | Suppose that you have an abstract for a scientific paper: the excess of events in the diphoton final state near 750 gev observed by atlas and cms can be explained within the nmssm near the @xmath0-symmetry limit .
both scalars beyond the standard model higgs boson have masses near 750 gev , mix strongly , and share sizeable production cross sections in association with b - quarks as well as branching fractions into a pair of very light pseudoscalars .
pseudoscalars with a mass of @xmath1 mev decay into collimated diphotons , whereas pseudoscalars with a mass of @xmath2 mev can decay either into collimated diphotons or into three @xmath3 resulting in collimated photon jets .
various such scenarios are discussed ; the dominant constraints on the latter scenario originate from bounds on radiative @xmath4 decays , but they allow for a signal cross section up to 6.7 fb .
lpt orsay 16 - 07 + lupm:16 - 004 + * ulrich ellwanger@xmath5 and cyril hugonie@xmath6 * + .
And you have already written the first three sentences of the full article: in december 2015 the atlas and cms collaborations have reported excesses in the search for resonances decaying into pairs of photons for diphoton invariant masses around 750 gev @xcite . in atlas
, excesses appeared in the two @xmath7 bins 710750 gev ( 14 events vs. 6.3 expected ) and 750 - 790 gev ( 9 events vs. 5.0 expected ) , with a local significance of @xmath8 ( assuming a large width of @xmath9 gev ; @xmath10 in the narrow width approximation ) . in cms , excesses appear in the @xmath7 bin 750770 gev for photons in the ebeb category ( 5 events vs. 1.9 expected ) and ebee category ( 6 events vs. 3.5 expected ) , but less in the bin 730 - 750 gev ( 4 events vs. 2.1 expected for photons in the ebeb category , 1 event vs. 4.0 expected for photons in the ebee category , considered as less sensitive ) .
the local significance of the excesses is @xmath11 for cms in the narrow width approximation ..
Please generate the next two sentences of the article | the global significances of the signals of @xmath12 are not overwhelming and compatible with statistical fluctuations . still
, the fact that the region of invariant diphoton masses is very similar for atlas and cms has stirred quite some excitement resulting in a huge number of possible explanations . |
4,854 | Suppose that you have an abstract for a scientific paper: we calculate the volumes of the hyperbolic twist knot cone - manifolds using the schlfli formula .
even though general ideas for calculating the volumes of cone - manifolds are around , since there is no concrete calculation written , we present here the concrete calculations .
we express the length of the singular locus in terms of the distance between the two axes fixed by two generators . in this way
the calculation becomes easier than using the singular locus directly .
the volumes of the hyperbolic twist knot cone - manifolds simpler than stevedore s knot are known . as an application
, we give the volumes of the cyclic coverings over the hyperbolic twist knots . .
And you have already written the first three sentences of the full article: thurston ( * ? ? ?
* chapter 5 ) showed that a holonomy representation @xmath0 of the group of a hyperbolic knot @xmath1 in @xmath2 can be deformed into a one - parameter family @xmath3 of representations to give a corresponding one - parameter family @xmath4 of singular complete hyperbolic manifolds , the hyperbolic _ cone - manifolds _ of a knot @xmath1 .
let @xmath5 be a meridian of @xmath1 ..
Please generate the next two sentences of the article | kojima @xcite showed further that @xmath6 is totally determined by the action of @xmath7 which is a rotation of angle @xmath8 around the fixed axis of @xmath9 .
a point on @xmath1 of the cone - manifold @xmath6 is in the core of a neighborhood isometric to a cylinder made of an angle @xmath8 wedge by identifying the two boundaries . |
4,855 | Suppose that you have an abstract for a scientific paper: in this work we analyze the instability conditions for spin - density - waves ( sdw ) formation on the surface of strong topological insulators . we find that for a certain range of fermi - energies and strength of interactions the sdw state is favored compared to the unmagnetized and the uniform - magnetization states .
we also find that the sdw are of spiral nature and for a certain range of parameters a skyrmion - lattice may form on the surface .
we show that this phase may have a non trivial chern - number even in the absence of an external magnetic field .
the gapless surface states of strong topological insulators have drawn a great deal of attention over the past few years .
these metallic states arise from a topologically non - trivial band structure @xcite and are protected as long as time reversal symmetry is maintained .
this topological feature may lead to novel quantum states on the surface of these materials , such as majorana fermions and fractional excitations @xcite . in a previous work @xcite it was shown that for a strong enough electron - electron interaction , both of the short range and the coulomb types , the surface of a strong topological insulator is unstable to the formation of spontaneous uniform magnetization .
other works @xcite suggested that a spin - density - wave state ( sdw ) is likely to occur due to a strong fermi - surface nesting . in this work
we explore the conditions under which the sdw state is favored over the unmagnetized and the uniform - magnetization states .
moreover , we find that for a certain range of parameters , a skyrmion - lattice may form on the surface .
we also elaborate on the topological properties of this phase and claim that a network of one - dimensional chiral channels can be established on the surface .
we start by analyzing the spin - susceptibility function .
the non - interacting hamiltonian of a @xmath0 topological insulator surface can be approximated by the fu model @xcite : @xmath1 where @xmath2 , @xmath3....
And you have already written the first three sentences of the full article: the stationary ( @xmath12 ) and non - interacting spin - susceptibility function , @xmath65 , is given in eq .
when the fermi - energy is at the hexagonal range and @xmath20 is close to one of nesting vectors , one of the eigenvalues of @xmath66 becomes much larger than the other two .
we denote the largest eigenvalue of @xmath66 as @xmath67 ..
Please generate the next two sentences of the article | we found that @xmath67 is maximized at the nesting vectors of the fermi - surface .
now , we would like the examine the temperature dependence of @xmath67 . in order to do so , we set @xmath19 . the ratio of @xmath68 and @xmath69 as a function of the temperature appears in fig . |
4,856 | Suppose that you have an abstract for a scientific paper: we study the use of final state particle pseudorapidity for measurements of @xmath0-channel resonances at the lhc . distinguishing the spin of an @xmath0-channel resonance
can , in principle , be accomplished using angular distributions in the centre - of - mass frame , possibly using a centre - edge asymmetry measurement , @xmath1 . in addition , forward - backward asymmetry measurements , @xmath2 , can be used to distinguish between models of extra neutral gauge bosons . in this note
we show how these measurements can be improved by using simple methods based on the pseudorapidity of the final state particles and present the expected results for @xmath2 and @xmath1 for several representative models . .
And you have already written the first three sentences of the full article: the startup of the cern large hadron collider ( lhc ) will allow the exploration of the tev energy regime and the testing of the multitude of proposed theories of physics beyond the standard model .
many of these theories predict the existence of massive , neutral @xmath0-channel resonances @xcite . for some models of new neutral gauge bosons ( @xmath3 )
, the lhc is expected to have a discovery reach upwards of 5 tev with 100 fb@xmath4 of integrated luminosity @xcite ..
Please generate the next two sentences of the article | this is a significant improvement over the current experimental limits for most models , which constrain @xmath3 masses to values greater than @xmath5 tev @xcite .
if a tev scale @xmath0-channel resonance were discovered , the immediate task would be to identify its origins . |
4,857 | Suppose that you have an abstract for a scientific paper: we consider a sorting machine consisting of two stacks in series where the first stack has the added restriction that entries in the stack must be in decreasing order from top to bottom .
the class of permutations sortable by this machine is known to be enumerated by the schrder numbers . in this paper
, we give a bijection between these sortable permutations of length @xmath0 and schrder paths of order @xmath1 : the lattice paths from @xmath2 to @xmath3 composed of east steps @xmath4 , north steps @xmath5 , and diagonal steps @xmath6 that travel weakly below the line @xmath7 . .
And you have already written the first three sentences of the full article: a stack is a sorting device that works by a sequence of push and pop operations .
this last - in , first - out machine was shown by knuth @xcite to sort a permutation if and only if that permutation avoids the pattern @xmath8 .
that is , if there are not three indices @xmath9 with @xmath10 , then it is possible to run @xmath11 through a stack and output the identity permutation ..
Please generate the next two sentences of the article | the class of stack - sortable permutations is enumerated by the catalan numbers . in the language of permutation patterns ,
any downset of permutations in the permutation containment ordering is a _ class _ , and every class has a _ basis _ , which consists of the minimal permutations not in the class . |
4,858 | Suppose that you have an abstract for a scientific paper: we provide a method to study hadronic matter at finite density in the context of the sakai - sugimoto model .
we introduce the baryon chemical potential through the external @xmath0 in the induced ( dbi plus cs ) action on the d8-probe - brane , where baryons are skyrmions .
vector dominance is manifest at finite density .
we derive the baryon density effect on the energy density , the dispersion relations of pion and vector mesons at large @xmath1 .
the energy density asymptotes to a constant at large density suggesting that dense matter at large @xmath1 freezes , with the pion velocity dropping to zero .
holographic dense matter enforces exactly the tenets of vector dominance , and screens efficiently vector mesons . at the freezing point
the @xmath2 coupling vanishes with a finite rho mass of about 20% its vacuum value .
hep - th/0608046 * dense hadronic matter in holographic qcd * + keun - young kim@xmath3 , sang - jin sin @xmath4 and ismail zahed@xmath3 + @xmath3 _ department of physics and astronomy , suny stony - brook , ny 11794 _
@xmath4 _ department of physics , hanyang university , seoul 133 - 791 , korea _ + .
And you have already written the first three sentences of the full article: recently there has been much interest @xcite in the ads / cft approach @xcite to study the non - perturbative aspects of gauge theories at large @xmath1 and strong coupling with even applications to heavy ion collision experiments such as jet quenching @xcite . on the other hand ,
dense qcd is of much relevance to compact stars and current heavy ion collisions .
this subject has been intensely studied in the past decade following the observation that at asymptotic densities qcd matter may turn to a color superconductor due to asymptotic freedom @xcite . at very large @xmath1.
Please generate the next two sentences of the article | there is evidence that the overhauser effect takes over with the formation of density waves @xcite .
indeed , at weak coupling the high degeneracy of the fermi surface causes quark - quark ( antiquark - antiquark ) pairing of the bcs kind with different color - flavor arrangements , while at large number of colors quark - antiquark pairing of the overhauser kind is favored . in strong coupling , |
4,859 | Suppose that you have an abstract for a scientific paper: we estimate the effects of viscosity on the phase space distribution appearing in the cooper - frye formula within the framework of the grad s fourteen moment method and find that there are non - trivialities in the discussion of a multi - component system .
we calculate the viscous corrections of particle spectra and elliptic flow coefficients from the distortion of the distribution using the flow and the hypersurface taken from a ( 3 + 1)-dimensional ideal hydrodynamic simulation .
we see that the bulk viscosity have visible effects on particle spectra .
the results suggest we should treat _ both _ shear and bulk viscosity carefully when constraining the transport coefficients from experimental data . .
And you have already written the first three sentences of the full article: ideal hydrodynamic models have been successful @xcite for the quark - gluon plasma ( qgp ) created at the relativistic heavy ion collider ( rhic ) in brookhaven national laboratory ( bnl ) .
our next step is to develop viscous hydrodynamic models because the success suggests the deviation from the equilibrium is not so large .
we mainly consider the effects of bulk viscosity since the importance of bulk viscosity in terms of the violation of scale invariance near the crossover temperature @xmath0 has been re - recognized @xcite ..
Please generate the next two sentences of the article | particle spectra are affected by viscosity in two ways : one is the variation of the flow @xmath1 and the hypersurface @xmath2 , the other is the distortion of the distribution @xmath3 because one needs to employ the cooper - frye formula @xmath4 at freezeout to convert the hydrodynamic results into the particle picture . here
the index @xmath5 denotes particle species and @xmath6 the degeneracy . |
4,860 | Suppose that you have an abstract for a scientific paper: a continuum dislocation model of formation of grains whose boundaries have a non - vanishing thickness is proposed . for a single crystal deforming in simple shear the lamellar structure of grains with thin layers containing dislocations as the geometrically necessary boundaries turns out to be energetically preferable .
the thickness and the energy of this type of grain boundary are computed as functions of the misorientation angle .
dislocations , grain boundaries , crystal plasticity , single crystal , shear . .
And you have already written the first three sentences of the full article: one of the main guiding principles in seeking an appropriate theory of formation of grains in metals and alloys during and after cold working processes producing severe plastic deformations has first been proposed by hansen and kuhlmann - wilsdorf @xcite in form of the so - called leds - hypothesis : the dislocation structures in the final state of deformation minimize the energy of crystals ( see also @xcite ) .
the main reason why the formation of grains becomes energetically preferable at severe plastic deformations lies in the non - convexity of the energy of crystal in this range @xcite . within the conventional crystal plasticity considered in @xcite
the minimization of such non - convex energy leads immediately to the infinitely fine lamellar structure with grain boundaries as sharp interfaces ..
Please generate the next two sentences of the article | however , as mentioned by kuhlmann - wilsdorf and hansen @xcite , typical grain boundaries , termed geometrically necessary boundaries , have as a rule a non - vanishing thickness and may contain a large number of dislocations and thus contradict the conventional crystal plasticity .
the question then arrises in this connection : what kind of continuum model may resolve this conflict ? |
4,861 | Suppose that you have an abstract for a scientific paper: in classical systems , our recent theoretical study provides new insight into how spatial constraint on the system connects with macroscopic properties , which lead to universal representation of equilibrium macroscopic physical property and structure in disordered states .
these important characteristics rely on the fact that statisitcal interdependence for density of microscopic states ( doms ) in configuration space appears numerically vanished at thermodynamic limit for a wide class of spatial constraints , while such behavior of the doms is not quantitatively well - understood so far .
the present study theoretically address this problem based on the random matrix with gaussian orthogonal ensemble , where corresponding statistical independence is mathematically guaranteed . using the generalized ising model
, we confirm that lower - order moment of density of eigenstates ( doe ) of covariance matrix of doms shows asymptotic behavior to those for random matrix with increase of system size .
this result supports our developed theoretical approach , where equilibrium macroscopic property in disordered states can be decomposed into individual contribtion from each generalized coordinate with the sufficiently high number of constituents in the given system , leading to representing equilibrium macroscopic properties by a few special microscopic states . .
And you have already written the first three sentences of the full article: in classical systems , statistical thermodynamics tells that macroscopic physical property ( or macroscopic structure ) in equilibrium state can be typically obtained by canonical average of @xmath0 , where @xmath1 denotes partition function , @xmath2 is temperature , @xmath3 means possible microscopic state on phase space , and @xmath4 and @xmath5 are energy and physical property ( or structure ) in state @xmath3 , respectively .
when @xmath2 goes to zero , summation is performed for the ground states having lowest energy .
when @xmath2 increases , due mainly to entropy contribution , the system can go into disordered states ( e.g. , states above the critical temperature ) . in the disordered states ,.
Please generate the next two sentences of the article | direct determination of @xmath6 through the definition of canonical average is practically intractable , since number of possible microscopic states should astronomically increases with increase of system size .
thus , a variety of calculation techniques have been developed to effectively address @xmath6 . |
4,862 | Suppose that you have an abstract for a scientific paper: the restframe uv - to - optical flux ratio , characterizing the `` uv upturn '' phenomenon , is potentially the most sensitive tracer of age in elliptical galaxies ; models predict that it may change by orders of magnitude over the course of a few gyr . in order to trace the evolution of the uv upturn as a function of redshift
, we have used the far - uv camera on the space telescope imaging spectrograph to image the galaxy cluster cl0016 + 16 at @xmath0 .
our @xmath1 field includes four bright elliptical galaxies , spectroscopically confirmed to be passively evolving cluster members .
the weak uv emission from the galaxies in our image demonstrates that the uv upturn is weaker at a lookback time @xmath25.6 gyr earlier than our own , as compared to measurements of the uv upturn in cluster e and s0 galaxies at @xmath3 and @xmath4 .
these images are the first with sufficient depth to demonstrate the fading of the uv upturn expected at moderate redshifts .
we discuss these observations and the implications for the formation history of galaxies . .
And you have already written the first three sentences of the full article: because they are composed of old , passively evolving populations , elliptical galaxies offer great promise for tracing the evolution of the universe . whether elliptical galaxies formed through hierarchical merging or monolithic collapse , one of the major goals in extragalactic studies is the determination of the `` redshift of formation , '' @xmath5 , that marks the age where most of the stars in early - type galaxies formed .
recent studies of galaxy clusters out to @xmath6 indicate that most of the star formation had to be completed at high redshift ( @xmath7 ) , followed by quiescent evolution thereafter ( stanford , eisenhardt , & dickinson 1998 ; kodama et al .
1998 ) ..
Please generate the next two sentences of the article | the uv upturn is a sharp rise in the spectra of e and s0 galaxies shortward of restframe 2500 .
it provides a sensitive tracer of age for the oldest stars in these galaxies , and can potentially constrain @xmath5 . |
4,863 | Suppose that you have an abstract for a scientific paper: time - dependent quantities are calculated in the linear response limit for a correlated one dimensional model atom driven by an external quadrupolar time - dependent field . besides the analysis of the time - evolving energy change in the correlated two - particle system , and orthogonality of initial and final states , mehler s formula is applied in order to derive a point - wise decomposition of the time - dependent one - matrix in terms of time - dependent occupation numbers and time - dependent orthonormal , natural orbitals .
based on such exact spectral decomposition on the time domain , rnyi s entropy is also investigated .
considering the structure of the exact time - dependent one - matrix , an independent - particle model is defined from it which contains exact information on the single - particle probability density and probability current .
the resulting noninteracting auxiliary state is used to construct an effective potential and discuss its applicability . .
And you have already written the first three sentences of the full article: there are quantum mechanical problems in which the hamiltonian depends explicitly on time , for example , the interaction of the system with an external time - dependent field where @xmath0 . in such cases ,
the system does not remain in any stationary state , and the behavior of it is governed by the time - dependent schrdinger equation @xmath1 the problem will now be an initial - value ( cauchy ) problem of solving this partial differential equation for a prescribed initial condition at @xmath2 . when problems of this short are discussed formally , it is common to speak of the perturbation ( @xmath3 ) as causing _ transitions _ between eigenstates of @xmath4 . if this statement is interpreted to mean that the state has changed from its inital value to a final value , than it is incorrect .
the effect of a time - dependent perturbation is to produce a nonstationary state , rather than to cause a jump from one stationary state to another which were determined by considering boundary conditions solely . experiments open the possibility to investigate dynamical properties of confined systems . in that field , of particular interest.
Please generate the next two sentences of the article | is the response of the system to time - dependent variations of the confining field .
then , even assuming complete isolation of the many - body confined system from the environment , there is the question of how the correlation properties change |
4,864 | Suppose that you have an abstract for a scientific paper: top plus jets production at hadron collider allows us to study the couplings of the top quark . in the standard model ,
two single top processes contribute to the top - jets final state . beyond the standard model ,
additional direct top production can occur .
all three processes probe top gauge couplings including flavor mixing .
the structure of accompanying qcd jets allows us to separate the direct top signal from the qcd backgrounds as well as to disentangle the three top plus jets production mechanisms orthogonally to the usual bottom tags . .
And you have already written the first three sentences of the full article: experimental results from flavor physics and electroweak precision measurements have long established the standard model pattern of flavor and cp violation .
the only sources of flavor and cp violation are the yukawa couplings , and the one essentially unknown parameter is the relative coupling strength of the heavy third - generation quark to the @xmath0 boson , the ckm mixing angle @xmath1 @xcite .
its knowledge is crucial to establish the unitarity of the ckm mixing matrix in the standard model ..
Please generate the next two sentences of the article | because the su(3 ) symmetry of qcd does not see electroweak charges , this coupling can not be determined in qcd - mediated top pair production .
instead , we rely on the electroweak production process for a single top quark in association with a quark jet to measure this parameter of the standard model . |
4,865 | Suppose that you have an abstract for a scientific paper: we report the first interstellar detection of c - c@xmath0d@xmath1 .
the doubly deuterated cyclopropenylidene , a carbene , has been detected toward the starless cores tmc-1c and l1544 using the iram 30 m telescope .
the @xmath2 , @xmath3 , and @xmath4 transitions of this species have been observed at 3 mm in both sources .
the expected 1:2 intensity ratio has been found in the 3@xmath5 - 2@xmath6 and 3@xmath7 - 2@xmath8 lines , belonging to the para and ortho species respectively .
we also observed lines of the main species , c - c@xmath0h@xmath1 , the singly deuterated c - c@xmath0hd , and the species with one @xmath9c off of the principal axis of the molecule , c - h@xmath9cc@xmath1h .
the lines of c - c@xmath0d@xmath1 have been observed with high signal to noise ratio , better than 7.5@xmath10 in tmc-1c and 9@xmath10 in l1544 .
the abundance of doubly deuterated cyclopropenylidene with respect to the normal species is found to be ( 0.4 - 0.8)% in tmc-1c and ( 1.2 - 2.1)% in l1544 .
the deuteration of this small hydrocarbon ring is analysed with a comprehensive gas - grain model , the first including doubly deuterated species .
the observed abundances of c - c@xmath0d@xmath1 can be explained solely by gas - phase processes , supporting the idea that c - c@xmath0h@xmath1 is a good indicator of gas - phase deuteration . .
And you have already written the first three sentences of the full article: investigating deuterium chemistry is useful to put constraints on the ionization fraction , temperature , density and thermal history of dense molecular clouds @xcite .
the observations of multiply deuterated molecules in space , e.g. @xcite and references therein , have shown the necessity to reexamine some reaction rates in chemical networks @xcite , elemental d / h ratio in cold dense gas @xcite and the density structure in sources such as l1544 and @xmath11 oph d @xcite , as well as the effects of accretion on grains @xcite , possible effects of internal dynamical motion @xcite , and the evolution of ice mantles in dense clouds and cores @xcite .
the first multiply deuterated interstellar molecule detected has been d@xmath1co almost twenty years ago @xcite . since then.
Please generate the next two sentences of the article | , the study of deuterated molecules in the ism has rapidly increased as they have been proven to be a unique observational probe of the early stages in low - mass star formation .
multiply deuterated species such as triply deuterated ammonia have been detected with a surprisingly high abundance ratio of 10@xmath12 with respect to their fully hydrogenated forms @xcite . by comparing this ratio with the elemental d / h ratio ( 1.65@xmath13 , linsky et al . |
4,866 | Suppose that you have an abstract for a scientific paper: we present the results from an optical study of the stellar & star formation properties of ngc 925 using the wiyn 3.5 m telescope .
images in b , v , r , & h@xmath0 reveal a galaxy that is fraught with asymmetries . from isophote
fits we discover that the bar center is not coincident with the center of the outer isophotes nor with the dynamical center ( from pisano _ et al .
_ 1998 ) .
cuts across the spiral arms reveal that the northern arms are distinctly different from the southern arm .
the southern arm not only appears more coherent , but the peaks in stellar and h@xmath0 emission are found to be coincident with those of the h i distribution , while no such consistency is present in the northern disk .
we also examine the gas surface density criterion for massive star formation in ngc 925 , and find that its behavior is more consistent with that for irregular galaxies , than with late - type spirals . in particular , star formation persists beyond the radius at which the gas surface density falls below the predicted critical value for star formation for late - type spirals .
such properties are characteristic of magellanic spirals , but are present at a less dramatic level in ngc 925 , a late - type spiral . .
And you have already written the first three sentences of the full article: this paper is part of an ongoing series of papers studying the general h i and optical properties of late - type barred spiral galaxies ( sbc - sd , hereafter ltbs ) .
we will examine the stellar and star forming properties of ngc 925 based on observations from the wiyn 3.5 m telescope .
we previously observed ngc 925 and ngc 1744 , both ltbs , in h i as part of a study of the gaseous properties of this class of galaxies ( pisano _ et al ..
Please generate the next two sentences of the article | _ , 1998 , hereafter paper i ) , and to determine the pattern speed of their bars ( elmegreen _ et al .
ngc 925 was chosen for study because it is a nearby ( @xmath19.3 mpc , silbermann _ et al . |
4,867 | Suppose that you have an abstract for a scientific paper: measurements of primordial non - gaussianity ( @xmath0 ) open a new window onto the physics of inflation .
we describe a fast cubic ( bispectrum ) estimator of @xmath0 , using a combined analysis of temperature and polarization observations .
the speed of our estimator allows us to use a sufficient number of monte carlo simulations to characterize its statistical properties in the presence of real world issues such as instrumental effects , partial sky coverage , and foreground contamination .
we find that our estimator is optimal , where optimality is defined by saturation of the cramer rao bound , if noise is homogeneous .
our estimator is also computationally efficient , scaling as @xmath1 compared to the @xmath2 scaling of the brute force bispectrum calculation for sky maps with @xmath3 pixels . for planck
this translates into a speed - up by factors of millions , reducing the required computing time from thousands of years to just hours and thus making @xmath0 estimation feasible for future surveys .
our estimator in its current form is optimal if noise is homogeneous . in future
work our fast polarized bispectrum estimator should be extended to deal with inhomogeneous noise in an analogous way to how the existing fast temperature estimator was generalized . .
And you have already written the first three sentences of the full article: in the last few decades the advances in the observational cosmology have led the field to its `` golden age . ''
cosmologists are beginning to nail down the basic cosmological parameters , and have started asking questions about the nature of the initial conditions provided by inflation @xcite , which apart from solving the flatness and horizon problem , also gives a mechanism for producing the seed perturbations for structure formation @xcite , and other testable predictions .
the main predictions of a canonical inflation model are : ( i ) spatial flatness of the observable universe , ( ii ) homogeneity and isotropy on large scales of the observable universe , ( iii ) nearly scale invariant and adiabatic primordial density perturbations , and ( iv ) primordial perturbations to be very close to gaussian ..
Please generate the next two sentences of the article | the cosmic microwave background ( cmb ) data from the wilkinson anisotropy probe ( wmap ) @xcite , both temperature @xcite and polarization @xcite anisotropies , have provided hitherto the strongest constraints on these predictions @xcite .
there is no observational evidence against simple inflation models . |
4,868 | Suppose that you have an abstract for a scientific paper: it has been recently shown that molecular clouds do not exhibit a unique shape for the column density probability distribution function ( ) . instead
, clouds without star formation seem to possess a lognormal distribution , while clouds with active star formation develope a power - law tail at high column densities . the lognormal behavior of the has been interpreted in terms of turbulent motions dominating the dynamics of the clouds , while the power - law behavior occurs when the cloud is dominated by gravity . in the present contribution we use thermally bi - stable numerical simulations of cloud formation and evolution to show that , indeed , these two regimes can be understood in terms of the formation and evolution of molecular clouds :
a very narrow lognormal regime appears when the cloud is being assembled .
however , as the global gravitational contraction occurs , the initial density fluctuations are enhanced , resulting , first , in a wider lognormal , and later , in a power - law .
we thus suggest that the observed of molecular clouds are a manifestation of their global gravitationally contracting state .
we also show that , contrary to recent suggestions , the exact value of the power - law slope is not unique , as it depends on the projection in which the cloud is being observed .
[ firstpage ] ism : general clouds kinematics and dynamics turbulence stars : formation .
And you have already written the first three sentences of the full article: it has been known since the first observations of molecular gas in star - forming clouds that the co lines exhibit supersonic line widths @xcite .
@xcite suggested that such supersonic linewidths could be produced by large - scale collapse of the molecular clouds .
in contrast , @xcite dismissed the idea of large - scale collapse with the argument that , if clouds were collapsing freely , the star formation rate in the galaxy should be a factor of 100 times larger than observed , leading to quick exhaustion of its gas content ..
Please generate the next two sentences of the article | those authors proposed instead that the large linewidths are produced by small - scale supersonic turbulence .
since then , the scenario of supersonic molecular cloud turbulence has received much attention , and turbulent models of molecular clouds have been developed by several groups ( see * ? ? ? |
4,869 | Suppose that you have an abstract for a scientific paper: we present an extended version of therminator , a monte carlo event generator dedicated to studies of the statistical production of particles in relativistic heavy - ion collisions .
the increased functionality of the code contains the following features : the input of any shape of the freeze - out hypersurface and the expansion velocity field , including the 3 + 1 dimensional profiles , in particular those generated externally with various hydrodynamic codes .
the hypersufraces may have variable thermal parameters , which allows for studies departing significantly from the mid - rapidity region , where the baryon chemical potential becomes large .
we include a library of standard sets of hypersurfaces and velocity profiles describing the rhic au+au data at @xmath0 gev for various centralities , as well as those anticipated for the lhc pb+pb collisions at @xmath1 tev . a separate code , femto - therminator , is provided to carry out the analysis of femtoscopic correlations which are an important source of information concerning the size and expansion of the system .
we also include several useful scripts that carry out auxiliary tasks , such as obtaining an estimate of the number of elastic collisions after the freeze - out , counting of particles flowing back into the fireball and violating causality ( typically very few ) , or visualizing various results : the particle @xmath2-spectra , the elliptic flow coefficients , and the hbt correlation radii .
we also investigate the problem of the back - flow of particles into the hydrodynamic region , as well as estimate the elastic rescattering in terms of trajectory crossings .
the package is written in c++ and uses the cern root environment . ,
, , , relativistic heavy - ion collisions , statistical hadronization , monte carlo event generator , lhc , rhic , sps , fair , nica * program summary * _ title of the program : _
+ _ catalog identifier : _ + _ program web page : _ + http://therminator2.ifj.edu.pl/ + _ licensing....
And you have already written the first three sentences of the full article: we introduce an updated and largely extended version of therminator @xcite , the thermal heavy ion generator , created to carry out the statistical hadronization in relativistic heavy - ion collisions .
numerous successful analyses have been performed with the help of our code over the last few years @xcite , contributing to better understanding of the involved evolution of the hot and dense system created in ultra - relativistic heavy - ion collision .
therminator 2 is a monte carlo generator written in c++ and using the standard cern root @xcite environment . that way ,.
Please generate the next two sentences of the article | apart from model applications , the code can be easily adapted for purposes directly linked to experimental data analysis , detector modeling , or estimates for the heavy - ion experiments at rhic , lhc , sps , fair , or nica .
originally , therminator was designed to perform the hadronic freeze - out on simple boost - invariant hypersurfaces , such as the cracow single - freeze - out model @xcite and the blast - wave model @xcite . meanwhile , |
4,870 | Suppose that you have an abstract for a scientific paper: we report the nqr study on the pressure - induced paramagnetic state in the antiferromagnetic ( af ) intermetallic compound ymn@xmath0 with the nel temperature @xmath1=100 k at ambient pressure . from the @xmath2 variation of the nuclear spin - lattice relaxation rate , @xmath3 of @xmath4mn above the critical pressure of 4 kbar
, the spin fluctuation feature is found to change below a temperature @xmath5 . at higher temperature than @xmath5
, the nuclear relaxation behavior is well described in terms of the self - consistent renomalized ( scr ) spin fluctuation theory for nearly af metals , whereas below @xmath5 a deviation is significant and @xmath6 exhibits a weak @xmath2 variation .
it is pointed out that @xmath5 coincides with the temperature below which a @xmath7 law in electrical resistivity is valid as expected for a fermi liquid ground state .
we proposed that these features are understood from the standpoint that the development of af spin fluctuation remains in short - range associated with the singlet formation among mn spins in each tetrahedron as suggested by the inelastic neutron experiments on y@xmath8sc@xmath9mn@xmath0 .
# 1@xmath10#1 pnumwidth2em .
And you have already written the first three sentences of the full article: in a series of intermetallic compound rmn@xmath0 ( r = rare earth ) , an existence of magnetic moments on mn sites depends largely on an inter - atomic mn - mn distance@xcite . above a critical distance of @xmath11=2.7
@xmath12 m there exists a magnetic moment on the mn which is antiferromagnetically ordered in general . below this critical distance
the ground state remains paramagnetic down to lowest temperature ..
Please generate the next two sentences of the article | this fact that the mn - mn inter - atomic distance plays a key - role in determining their magnetic properties indicates that these compounds may be magnetically sensitive to such a perturbation as a chemical substitution or an application of pressure .
an interesting possibility is then that an application of pressure induces quantum critical phase transition governed by the zero point quantum spin fluctuation . in particular |
4,871 | Suppose that you have an abstract for a scientific paper: the time - dependent numerical renormalization - group approach ( td - nrg ) , originally devised for tracking the real - time dynamics of quantum - impurity systems following a single quantum quench , is extended to multiple switching events .
this generalization of the td - nrg encompasses the possibility of periodic switching , allowing for coherent control of strongly correlated systems by an external time - dependent field . to this end , we have embedded the td - nrg in a hybrid framework that combines the outstanding capabilities of the numerical renormalization group to systematically construct the effective low - energy hamiltonian of the system with the prowess of complementary approaches for calculating the real - time dynamics derived from this hamiltonian .
we demonstrate the power of our approach by hybridizing the td - nrg with the chebyshev expansion technique in order to investigate periodic switching in the interacting resonant - level model .
although the interacting model shares the same low - energy fixed point as its noninteracting counterpart , we surprisingly find the gradual emergence of damped oscillations as the interaction strength is increased .
focusing on a single quantum quench and using a strong - coupling analysis , we reveal the origin of these interaction - induced oscillations and provide an analytical estimate for their frequency .
the latter agrees well with the numerical results . .
And you have already written the first three sentences of the full article: the quantitative description of real - time dynamics in strongly correlated systems is one of the outstanding challenges of contemporary condensed - matter physics , with relevance to varied systems ranging from cold atoms @xcite and dissipative systems @xcite to quantum - dot devices @xcite and biological donor - acceptor molecules .
@xcite alongside fundamental question concerning the underlying time scales and the long - time behavior , there are many technological issues that require careful investigation . for example , the decoherence and relaxation of spins appears to be the major obstacle for the realization of quantum - computing algorithms in real systems .
@xcite another key issue is the understanding of coherent control and the switching characteristics of nanodevices such as single - electron transistors ..
Please generate the next two sentences of the article | @xcite these and related topics require the development and application of suitable many - body techniques .
@xcite over the years , the kadanoff - baym @xcite and keldysh @xcite techniques have proven to be accurate tools for describing the real - time dynamics of weakly correlated systems such as light - matter interaction in semiconductors @xcite and the decoherence and relaxation of an impurity spin well above the kondo temperature . |
4,872 | Suppose that you have an abstract for a scientific paper: when existing , cumulants can provide valuable information about a given distribution and can in principle be used to either fully reconstruct or approximate the parent distribution function . a previously reported cumulant expansion approach for franck - condon profiles [ faraday discuss .
, 150 , 363 ( 2011 ) ] is extended to describe also the profiles of vibronic transitions that are weakly allowed or forbidden in the franck - condon approximation ( non - condon profiles ) . in the harmonic approximation the cumulants of the vibronic spectral profile can be evaluated analytically and numerically with a coherent state - based generating function that accounts for the duschinsky effect . as illustration ,
the one - photon @xmath0 uv absorption spectrum of benzene in the electric dipole and ( linear ) herzberg - teller approximation is presented herein for zero kelvin and finite temperatures . .
And you have already written the first three sentences of the full article: vibrationally resolved electronic spectra ( _ e.g. _ one - photon absorption and emission spectra ) are within the born - oppenheimer framework usually interpreted in terms of franck - condon ( fc ) factors ( fcfs ) @xcite .
accordingly , one can try to obtain the shape of the spectral profile for a fc - allowed transition from computed fcfs in frequency domain .
however , the evaluation of fcfs for large molecular systems is challenging even within the harmonic approximation if one has to take duschinsky mode mixing ( rotation ) @xcite into account ..
Please generate the next two sentences of the article | this is because multi - variate hermite polynomials have then to be evaluated for each fc integral , rather than only uni - variate hermite polynomials as is the case for the comparatively simple parallel harmonic oscillator model .
the computational task becomes more difficult as the molecular size and temperature increases because the number of fc integrals grows vastly . to describe fc - forbidden or weakly allowed transitions , |
4,873 | Suppose that you have an abstract for a scientific paper: the power spectra of black hole binaries have been well studied for decades , giving a very detailed phenomenological picture of the variability properties and their correlation with the energy spectrum ( spectral state ) of the source . here
we take the truncated disc / hot inner flow picture which can describe the spectral changes , and show that propagating mass accretion rate fluctuations in the hot flow can match the broad band power spectral properties seen in black hole binaries , i.e. give approximately band limited noise between a low and high frequency break .
the low frequency break marks the viscous timescale at the outer edge of the hot inner flow , which is the inner edge of the truncated disc .
the fluctuations in mass accretion rate propagate towards the central object in a finite time meaning the high frequency break is more complex than simply the viscous timescale at the inner edge of the hot flow because fluctuations on timescales shorter than the propagation time are incoherent .
the model also predicts the lense - thirring precession timescale of the hot flow , as this is set by the combination of inner and outer radius of the flow , together with its surface density which is self consistently calculated from the propagating fluctuations .
we show that this naturally gives the observed relation between the low frequency break and qpo frequency as the outer radius of the flow moves inwards , and that this model predicts many of the observed qpo properties such as correlation of coherence with frequency , and of the recently discovered correlation of frequency with flux on short timescales .
we fit this total model of the variability to a sequence of 5 observed power spectra from the bright black hole binary xte j1550 - 564 as the source transitioned from a low / hard to very high state .
this is the first time that a power spectrum from a black hole binary has been fit with a physical model for the variability .
the data are well fit if the inner radius of the flow....
And you have already written the first three sentences of the full article: emission observed from black hole binaries ( bhbs ) is variable on both long and short timescales . on the longest timescales , changes in mass accretion rate drive changes in spectral state . at the lowest luminosities ,
the system is typically seen in the low / hard state , where the spectrum is dominated by a hard ( photon index @xmath1 ) power law tail , peaking at 100 kev .
as the source brightens , there is an increasing contribution from the disc at low energies and the tail softens towards @xmath2 ( intermediate state ) ..
Please generate the next two sentences of the article | the tail can then either remain strong as the source flux increases , giving the very high state ( @xmath3 ) or it can carry only a very small fraction of the luminosity , giving the high / soft state ( @xmath4 ) ( e.g. see reviews by remillard & mcclintock 2006 ; done , gierlinski & kubota 2007 , hereafter dgk07 ) . much of this long term spectral evolution can be successfully described by the truncated disc model ( dgk07 ) . here , the assumption is that the cool , geometrically thin , optically thick disc is truncated at some radius , @xmath5 , which is much larger than the last stable orbit , @xmath6 at the lowest luminosities .
the inner accretion flow extends from @xmath5 to an innermost radius , @xmath7 , forming some sort of hot , geometrically thick , optically thin ( optical depth @xmath8 ) flow , similar to an advection dominated accretion flow ( adaf , narayan & yi 1995 ) . |
4,874 | Suppose that you have an abstract for a scientific paper: we extend and generalize results of scheiderer ( 2006 ) on the representation of polynomials nonnegative on two - dimensional basic closed semialgebraic sets .
our extension covers some situations where the defining polynomials do not satisfy the transversality condition .
such situations arise naturally when one considers semialgebraic sets invariant under finite group actions . .
And you have already written the first three sentences of the full article: let @xmath0 $ ] be the ring of polynomials in @xmath1 variables with real coefficients .
a * preordering * of a general ring @xmath2 ( commutative with @xmath3 ) is a subsemiring of @xmath2 which contains the squares . in other words ,
a preordering of @xmath2 is a subset of @xmath2 which contains all @xmath4 , @xmath5 , and is closed under addition and multiplication . for a finite subset @xmath6 of @xmath7 , we write @xmath8 for the preordering of @xmath7 generated by @xmath9 , and @xmath10 for the set of all @xmath11 satisfying @xmath12 ( the basic closed semialgebraic set defined by @xmath9 ) ..
Please generate the next two sentences of the article | note that @xmath10 is uniquely determined by @xmath8 , but typically @xmath8 is not uniquely determined by @xmath10 . for a subset @xmath13 of @xmath14 , we write @xmath15 for the set of all elements of @xmath7 that are nonnegative on @xmath13 .
we always have that @xmath16 . |
4,875 | Suppose that you have an abstract for a scientific paper: for the low - energy anti - neutrino reaction , @xmath0 , which is of great current interest in connection with on - going high - precision neutrino - oscillation experiments , we calculate the differential cross section in a model - independent effective field theory ( eft ) , taking into account radiative corrections of order @xmath1 . in eft , the short - distance radiative corrections are subsumed into well - defined low - energy constants the values of which can in principle be determined from the available neutron beta - decay data . in our low - energy eft ,
the order-@xmath1 radiative corrections are considered to be of the same order as the nucleon recoil corrections , which include the weak magnetism " contribution .
these recoil corrections have been evaluated as well .
we emphasize that eft allows for a systematic evaluation of higher order corrections , providing estimates of theoretical uncertainties in our results .
+ 0.5 cm u. raha , f. myhrer and k.kubodera 0.5 cm department of physics and astronomy , university of south carolina , columbia , sc 29208 .
And you have already written the first three sentences of the full article: low - energy anti - neutrinos from nuclear reactors are well suited to determine the neutrino mixing angle @xmath2 , which is important for the search of cp violation in the leptonic sector ; see , e.g. , refs .
the double - chooz @xcite , daya bay @xcite , and reno collaborations @xcite are aiming to measure @xmath2 with very high precision with the use of @xmath3 s produced in nuclear reactors . the present upper bound to this quantity reported by the chooz @xcite and minos @xcite collaborations is : @xmath4 .
the double - chooz , daya bay and reno experiments monitor the inverse beta - decay reaction on a hydrogen target |_e + p e^+ + n [ dcdb ] [ eq : reaction ] for a known anti - neutrino energy flux ..
Please generate the next two sentences of the article | the positron yield is measured as a function of the positron energy .
an accurate extraction of the mixing angle @xmath2 from an analysis of the measured positron yield requires a precise knowledge of the radiative corrections ( rcs ) . in earlier papers @xcite |
4,876 | Suppose that you have an abstract for a scientific paper: the superfluid density is a fundamental quantity describing the response to a rotation as well as in two - fluid collisional hydrodynamics .
we present extensive calculations of the superfluid density @xmath0 in the bcs - bec crossover regime of a uniform superfluid fermi gas at finite temperatures.we include strong - coupling or fluctuation effects on these quantities within a gaussian approximation .
we also incorporate the same fluctuation effects into the bcs single - particle excitations described by the superfluid order parameter @xmath1 and fermi chemical potential @xmath2 , using the nozires and schmitt - rink ( nsr ) approximation .
this treatment is shown to be necessary for consistent treatment of @xmath0 over the entire bcs - bec crossover .
we also calculate the condensate fraction @xmath3 as a function of the temperature , a quantity which is quite different from the superfluid density @xmath0 .
we show that the mean - field expression for the condensate fraction @xmath3 is a good approximation even in the strong - coupling bec regime .
our numerical results show how @xmath0 and @xmath3 depend on temperature , from the weak - coupling bcs region to the bec region of tightly - bound cooper pair molecules . in a companion paper by the authors ( cond - mat/0609187 ) , we derive an equivalent expression for @xmath0 from the thermodynamic potential , which exhibits the role of the pairing fluctuations in a more explicit manner . .
And you have already written the first three sentences of the full article: in the last few years , the bcs - bec crossover in two - component fermi superfluids has become a central topic in ultracold atom physics@xcite .
this crossover is of especial interest since the superfluidity continuously changes from the weak - coupling bcs - type to the bose - einstein condensation ( bec ) of tightly bound cooper pairs , as one increases the strength of a pairing interaction@xcite .
thus the bcs - bec crossover enables us to study fermion superfluidity and boson superfluidity in a unified manner ..
Please generate the next two sentences of the article | the superfluid density @xmath0 is a fundamental quantity which describes the response of a superfluid which arises from a bec@xcite .
the superfluid density was first introduced by landau as part of the two - fluid theory of superfluid @xmath4he@xcite . at @xmath5 |
4,877 | Suppose that you have an abstract for a scientific paper: calculations for open quantum systems are performed usually by taking into account their embedding into one common environment , which is mostly the common continuum of scattering wavefunctions .
realistic quantum systems are coupled however often to more than one continuum .
for example , the conductance of an open cavity needs at least two environments , namely the input and the output channel . in the present paper ,
we study generic features of an open quantum system coupled to two channels .
we compare the results with those characteristic of a one - channel system . of special interest
is the parameter range which is influenced by singular ( exceptional ) points . here , the states of the system are mixed via the environment and the dynamics is determined , in any case , by nonlinear processes .
these processes restore the resonance structure of the cross section in the one - channel case , such that there is no need to consider them in calculations for concrete systems . in the two - channel case , however , they cause new effects .
most interesting is the enhanced conductance of an open cavity in this parameter range .
this enhancement follows directly from the properties of the eigenstates of a non - hermitian hamilton operator ( and is not related to the existence of a superradiant state ) .
the study of the conductance allows , among others , an experimental test of the non - hermitian quantum physics . .
And you have already written the first three sentences of the full article: quantum systems are localized in a finite well - defined space area .
this area may be determined by certain boundary conditions ( e.g. in quantum dots or quantum billiards ) or by self - organization ( e.g. in atomic nuclei ) .
the shape of the nucleus is , indeed , an essential part of nuclear spectroscopic investigations and is characteristic of every nucleus . it may be spherical as well as oblate or prolate or even more complicated , see @xcite ..
Please generate the next two sentences of the article | the spectroscopic properties of quantum systems are studied usually by means of a hermitian hamilton operator @xmath0 , the eigenstates of which are discrete .
due to the embedding of the system into a continuum of scattering wavefunctions , the lifetimes of its states become usually finite . |
4,878 | Suppose that you have an abstract for a scientific paper: various recent results of new particle searches at the fermilab tevatron are presented .
no evidence is found for supersymmetric particles ( chargino , gluino ) , leptoquark bosons and heavy gauge bosons in @xmath0 collisions at @xmath1 = 1.8 tev .
excluded mass regions for each particle are determined .
u l # 1 # 1#2 -0.6 cm
-0.2 cm -0.2 cm @xmath2 teruki kamon + department of physics , texas a&m university + college station , texas 77843 - 4242 + on behalf of the cdf and dcollaborations + .
And you have already written the first three sentences of the full article: with the data from cern s lep electron - positron collider , desy s hera electron - proton collider and fermilab s tevatron proton - antiproton collider , the standard model ( sm ) has received overwhelming experimental support .
no new physics has been observed essentially at mass below @xmath3 .
thus , it is imperative that the fermilab tevatron , the world s highest energy particle collider , be used for searches of new phenomena ..
Please generate the next two sentences of the article | the cdf and dexperiments have been actively studying their data for evidence of previously unobserved particles .
presented below are the latest results of searches at the tevatron for supersymmetric particles ( chargino , gluino ) , leptoquark bosons and heavy gauge bosons . |
4,879 | Suppose that you have an abstract for a scientific paper: the australia telescope compact array ( atca ) has been used to survey at 1.4 ghz , a small region ( @xmath0 3 sq deg ) overlapping with the 2df galaxy redshift survey @xcite .
we surveyed with a varying radio sensitivity , ranging from 1 mjy 20 @xmath1jy ( @xmath2 ) .
there are 365 2dfgrs sources with z @xmath3 0.001 lying within the surveyed region , of which 316 have reliable spectral classification .
following @xcite , we visually classified 176 as agn or early - type galaxies , and 140 as star - forming galaxies .
we derived radio flux density measurement or upperlimits for each of the 365 2dfgrs sources .
the fraction of radio detected 2dfgrs star - forming galaxies increases from @xmath4 50% at @xmath4 0.7 mjy up to @xmath4 60% at @xmath4 0.2 mjy .
the mean redshift for the fraction of radio detected star - forming galaxies increases with increasing radio detection sensitivity , while the mean redshift is fairly constant for the agn / early - type fraction .
we found very similar radio detection rates of 2dfgrs galaxies for both the agn / early - type and star - forming components .
the radio detection rate increases approximately linearly with respect to the rate of increase in radio detection sensitivity .
we derived the radio luminosity function for our sample and it was found to be consistent with that of @xcite .
we have also compared the total flux densities of nvss sources common to our survey , and we discuss strategies for a large - scale radio survey of the 2dfgrs sample .
surveys galaxies : statistics galaxies : evolution galaxies : distances and redshifts galaxies : fundamental parameters
radio continuum : galaxies .
And you have already written the first three sentences of the full article: the decimetric synchrotron emission from galaxies is believed to arise from relativistic electrons accelerated by shock waves either in the interstellar medium , or in structures associated with an active galactic nucleus ( agn ) . in the former case
, there is evidence that the decimetric luminosity is proportional to the rate of massive star formation , the link arising because supernovas are perhaps the dominant source of accelerating shock waves @xcite . in the later case , the decimetric luminosity of an agn may be related to the physical properties of the underlying black hole , and the rate and mode of mass accretion by that black hole @xcite .
observations of the total decimetric luminosity of a galaxy thus allow an estimate of the extinction - free star - formation rate in galaxies where agn emission can be considered negligible ..
Please generate the next two sentences of the article | conversely , where the star formation rate is relatively low they provide information on the character of activity excited by a nuclear black hole .
a few galaxies emit significant decimetric from combined nuclear star - formation and agn activity @xcite . |
4,880 | Suppose that you have an abstract for a scientific paper: we show that a constant - potential time - independent schrdinger equation with dirichlet boundary data can be reformulated as a laplace equation with dirichlet boundary data . with this reformulation , which we call the duffin correspondence ,
we provide a classical walk on spheres ( wos ) algorithm for monte carlo simulation of the solutions of the boundary value problem .
we compare the obtained duffin wos algorithm with existing modified wos algorithms . .
And you have already written the first three sentences of the full article: we consider stochastic simulation ( or monte carlo simulation ) of the solution of a dirichlet boundary value problem of a time - independent schrdinger equation with constant potential . for positive potentials this equation
is called the yukawa equation or the linearized poisson boltzmann equation . for zero potential
the equation is known as the laplace equation . for negative potential.
Please generate the next two sentences of the article | it is known as the helmholtz equation .
the connection between the dirichlet boundary value problems and the brownian motion date back to kakutani @xcite , who provided a stochastic representation of the solution of the laplace equation with dirichlet boundary conditions in terms of the exit locations of a brownian motion . |
4,881 | Suppose that you have an abstract for a scientific paper: we present the discovery of balmer line absorption from h@xmath0 to h@xmath1 in an iron low - ionization broad absorption line ( felobal ) quasar sdss j152350.42 + 391405.2 ( hereafter 1523 ) , by the quasi - simultaneous optical and near - infrared spectroscopy .
the balmer line absorption is at @xmath2 and blueshifted by @xmath3 km s@xmath4with respect to the balmer emission lines .
all balmer bals have uniform absorption profile with the widths of @xmath512,000 km s@xmath4 .
we also found the absorption trough in * @xmath610830 with the same velocity and width in the @xmath7-band triplespec spectrum of 1523 .
this object is only the tenth active galactic nucleus known to exhibit non - stellar balmer absorption , and also the case with the highest velocity and broadest balmer absorption lines which have ever been found .
a cloudy analysis shows that the absorbers require an gas density of @xmath8 and an ionization parameter of @xmath9 .
they locate at a distance of @xmath10 pc from the central ionizing source which is slightly farther than that of belrs . furthermore
, 1523 is one of the brightest balmer - bal quasar ever reported , with unique iron absorption variations , making it as the most promising candidate for follow up high - resolution spectroscopy , multi - band observations , and long - term monitoring . .
And you have already written the first three sentences of the full article: evidences accumulated in the past decade point to the phenomenon that feedback from active galactic nuclei ( agns ) plays a crucial role in galaxy formation and evolution .
outflows in agns connect the central supermassive black holes ( smbhs ) to their host galaxies , and regulate their co - evolution ( granato et al .
2004 ; scannapieco & oh 2004 ; hopkins et al . 2008 ; also see antonuccio - delogu & silk 2010 for a recent review ) ..
Please generate the next two sentences of the article | observationally , the most direct and obvious performance of agn outflows is the high - speed blueshifted broad absorption lines ( bals ) . because of the high fraction in optically selected quasars ( 10%-20% ) , high - ionization bal ( hibal ) quasars
are widely studied , with strong absorption troughs in high ionization ions such as , , , and , up to a velocity of @xmath11 ( e.g. , weymann et al . |
4,882 | Suppose that you have an abstract for a scientific paper: we calculate the _ full _ electroweak one loop corrections to the decay of the cp
odd higgs boson @xmath0 into scalar fermions in the minimal supersymmetric extension of the standard model .
for this purpose many parameters of the mssm have to be properly renormalized in the on shell renormalization scheme .
we have also included the susy qcd corrections . for the decay into bottom squarks and tau sleptons , especially for large @xmath1
, the corrections can be very large making the perturbation expansion unreliable .
we solve this problem by an appropriate definition of the tree
level coupling in terms of running fermion masses and running trilinear couplings @xmath2 .
we also discuss the decay of heavy scalar fermions into light scalar fermions and @xmath0 .
we find that the corrections can be sizeable and therefore can not be neglected .
hep - ph/0308146 * improved full one loop corrections + to @xmath3 and @xmath4 * + c. weber , h. eberl , w. majerotto + .
And you have already written the first three sentences of the full article: the search for a higgs boson is the primary goal of all present and future high energy experiments at the tevatron , lhc or an @xmath5 linear collider . whereas the standard model ( sm ) predicts just one higgs boson , with the present lower bound of its mass @xmath6 ( at 95% confidence level ) @xcite , extensions of the sm allow for more higgs bosons . in particular , the minimal supersymmetric standard model ( mssm ) contains five physical higgs bosons : two neutral cp even ( @xmath7 and @xmath8 ) , one neutral cp odd ( @xmath0 ) , and two charged ones ( @xmath9 ) @xcite .
the existence of a charged higgs boson or a cp odd neutral one would give clear evidence for physics beyond the sm .
for a discovery precise predictions for its decay modes and their branching ratios are necessary . in case.
Please generate the next two sentences of the article | supersymmetric ( susy ) particles are not too heavy , the higgs bosons can also decay into susy particles ( neutralinos @xmath10 , charginos @xmath11 , sfermions @xmath12 ) , @xmath13 ( @xmath14 = 1 4 ) , @xmath15 , @xmath16 ( @xmath17 = 1 , 2 ) , @xmath18 , @xmath19 . at tree
level , these decays were studied in @xcite . in particular , |
4,883 | Suppose that you have an abstract for a scientific paper: we present very large array ( vla ) and westerbork synthesis radio telescope ( wsrt ) 21-cm hi observations of 19 late - type low surface brightness ( lsb ) galaxies .
our main findings are that these galaxies , as well as having low surface brightnesses , have low hi surface densities , about a factor of @xmath0 lower than in normal late - type galaxies .
we show that lsb galaxies in some respects resemble the outer parts of late - type normal galaxies , but may be less evolved .
lsb galaxies are more gas - rich than their high surface brightness counterparts .
the rotation curves of lsb galaxies rise more slowly than those of hsb galaxies of the same luminosity , with amplitudes between 50 and 120 km s@xmath1 , and are often still increasing at the outermost measured point .
the shape of the rotation curves suggests that lsb galaxies have low matter surface densities .
we use the average total mass surface density of a galaxy as a measure for the evolutionary state , and show that lsb galaxies are among the least compact , least evolved galaxies .
we show that both @xmath2 and @xmath3 depend strongly on central surface brightness , consistent with the surface brightness mass - to - light ratio relation required by the tully - fisher relation .
lsb galaxies are therefore slowly evolving galaxies , and may well be low surface density systems in all respects .
galaxies : evolution galaxies : fundamental parameters galaxies : structure galaxies : spiral galaxies : kinematics and dynamics dark matter .
And you have already written the first three sentences of the full article: in recent years low surface brightness ( lsb ) galaxies have received an increasing amount of attention . with the advent of deep
, large - field surveys many of these galaxies have been discovered , both in clusters and in the field ( schombert et al .
1988 , 1992 [ hereafter sbsm ] , turner et al ..
Please generate the next two sentences of the article | 1993 , davies et al .
1994 , schwartzenberg et al . |
4,884 | Suppose that you have an abstract for a scientific paper: the analysis of the batse s count distribution within cosmological models suffers from observational uncertainties due to the variability of the bursts spectra : when batse observes bursts from different redshifts at a fixed energy band it detects photons from different energy bands at the source .
this adds a spectral dependence to the count distribution @xmath0 .
similarly variation of the duration as a function of energy @xcite at the source complicates the time dilation analysis .
it has even been suggested that these methods lead to inconsistent estimates of the redshift from which the bursts are observed@xcite .
clearly it would be best to combine the estimates and to perform a joint analysis of the strength and the duration of the bursts .
but for this we have to eliminate first the spectral dependence problem .
we describe here a new statistical formalism that performs the required blue shifting " of the count number and the burst duration in a statistical manner .
this formalism allows us to perform a combined best fit ( maximal likelihood ) to the count distribution , @xmath0 , and the duration distribution simultaneously .
the outcome of this analysis is a single best fit value for the redshift of the observed bursts . .
And you have already written the first three sentences of the full article: when batse observes bursts from different red - shifts at a fixed energy band it detects photons from different energy bands at the source . this spectral dependence complicates the interpretation of the peak - flux and time - dilation distributions .
so far several attempts have been made to overcome this problem by modeling the spectral shape of the bursts .
we suggest here a different method which is based on the availability of multi channel data in different energy bands ..
Please generate the next two sentences of the article | the basic idea beyond our scheme is that we
view " all bursts at the same intrinsic energy band independently of their red - shift by by scanning over the different channels until we find the most likely red - shift and using this value to blue - shift " back the observed spectrum to the initial spectrum at the source . |
4,885 | Suppose that you have an abstract for a scientific paper: we present _ xmm - newton _ spectral analysis of all 38 seyfert galaxies from the palomar spectroscopic sample of galaxies . these are found at distances of up to 67 mpc and
cover the absorbed 2 - 10 kev luminosity range @xmath0 .
our aim is to determine the distribution of the x - ray absorption in the local universe .
three of these are compton - thick with column densities just above @xmath1 and high equivalent width fek@xmath2 lines ( @xmath3 ev ) .
five more sources have low values of the x - ray to [ oiii ] flux ratio suggesting that they could be associated with obscured nuclei .
their individual spectra show neither high absorbing columns nor flat spectral indices .
however , their stacked spectrum reveals an absorbing column density of @xmath4 .
therefore the fraction of absorbed sources ( @xmath5 ) could be as high as @xmath6 % .
a number of seyfert-2 appear to host unabsorbed nuclei .
these are associated with low - luminosity sources @xmath7 .
their stacked spectrum again shows no absorption while inspection of the images , where available , shows that contamination from nearby sources does not affect the _ xmm - newton _ spectra in most cases .
nevertheless , such low luminosity sources are not contributing significantly to the x - ray background flux .
when we consider only the brighter , @xmath8 , 21 sources , we find that the fraction of absorbed nuclei rises to @xmath9 % while that of compton - thick sources to 15 - 20% . the fraction of compton - thick agn is lower than that predicted by the x - ray background synthesis model in the same luminosity and redshift range
. 2@xmath10 .
And you have already written the first three sentences of the full article: the moderate to high redshift universe has been probed at unparallelled depth with the most sensitive observations performed at x - ray wavelengths in the _ chandra _ deep fields .
the _ chandra _
2ms observations ( alexander et al . 2003 , luo et al . 2008 ) resolved about 80 per cent of the extragalactic x - ray light in the hard 2 - 10 kev band ( see brandt & hasinger 2005 for a review ) ..
Please generate the next two sentences of the article | these deep surveys find a sky density of 5000 sources per square degree , the vast majority of which are found to be agn through optical spectroscopy ( e.g. barger et al . 2003 ) .
in contrast , the optical surveys for qsos ( e.g. the combo-17 survey ) reach only a surface density about an order of magnitude lower ( e.g. wolf et al . 2003 ) . |
4,886 | Suppose that you have an abstract for a scientific paper: fully differential cross sections are calculated for the ionization of h@xmath0 by fast charged projectiles using a semiclassical model developed previously for the ionization of atoms . the method is tested in case of 4 kev electron and 6 mev proton projectiles .
the obtained results show good agreement with the available experimental data .
interference effects due to the two - center character of the target are also observed and analyzed . .
And you have already written the first three sentences of the full article: in the last few decades there was a considerable development in the theoretical description and experimental measurement of differential cross sections for charged particle impact ionization of atoms and molecules @xcite .
nowadays , the interest is focused on the in - detail analysis of the electron ejection from atomic or molecular targets @xcite .
these analyzes may be performed by measuring and calculating fully differential cross sections which gives us the most complete information about an ionization process ..
Please generate the next two sentences of the article | these quantities describe the entire energy and angular distribution of the ionized electron , residual ion and projectile . previously , based on the semiclassical impact parameter method
we have constructed a theoretical model to calculate fully differential cross sections for single ionization of light atoms . |
4,887 | Suppose that you have an abstract for a scientific paper: we investigate superconducting interference device ( squid ) with two asymmetric josephson junctions coupled to a mechanical resonator embedded in the loop of the squid .
we quantize this system in the case when the frequency of the mechanical resonator is much lower than the cavity frequency of the squid and in the case when they are comparable . in the first case ,
the radiation pressure and cross - kerr type interactions arise and are modified by asymmetry .
cross - kerr type coupling is the leading term at the extremum points where radiation pressure is zero . in the second case ,
the main interaction is single - photon beam splitter , which exists only at finite asymmetry .
another interaction in this regime is of cross - kerr type , which exists at all asymmetries , but generally much weaker than the beam splitter interaction .
increasing magnetic field can substantially enhance optomechanical couplings strength with the potential for the radiation pressure coupling to reach the single - photon strong coupling regime , even the ultrastrong coupling regime , in which the single - photon coupling rate exceeds the mechanical frequency . .
And you have already written the first three sentences of the full article: the progress in optomechanical systems , where an optical or microwave cavity is coupled to a mechanical resonator , was impressive in recent years@xcite .
the accomplishments in optomechanics include cooling mechanical resonator to its quantum ground state@xcite , prediction@xcite and observation@xcite of the optomechanically - induced transparency , squeezing of the cavity@xcite , and mechanical@xcite modes , and coherent state transfer@xcite .
many of these experiments have been realized using superconducting circuits , which enables to consider microwave cavities coupled to mechanical motion as possible building blocks for quantum information processing@xcite ..
Please generate the next two sentences of the article | the coupling between cavity and mechanical resonator plays a central role in optomechanics . in the published experiments ,
intrinsically weak radiation pressure coupling was amplified by increasing drive power of the cavity , which linearizes the effective optomechanical interaction of the system . |
4,888 | Suppose that you have an abstract for a scientific paper: the surfaces of three dimensional topological insulators ( 3d tis ) are generally described as dirac metals , with a single dirac cone .
it was previously believed that a gapped surface implied breaking of either time reversal @xmath0 or @xmath1 charge conservation symmetry .
here we discuss a novel possibility in the presence of interactions , a surface phase that preserves all symmetries but is nevertheless gapped and insulating .
then the surface must develop topological order of a kind that can not be realized in a 2d system with the same symmetries .
we discuss candidate surface states - non - abelian quantum hall states which , when realized in 2d , have @xmath2 and hence break @xmath0 symmetry .
however , by constructing an exactly soluble 3d lattice model , we show they can be realized as @xmath0 symmetric surface states .
the corresponding 3d phases are confined , and have @xmath3 magnetoelectric response .
two candidate states have the same 12 particle topological order , the ( read - moore ) pfaffian state with the neutral sector reversed , which we term t - pfaffian topological order , but differ in their @xmath0 transformation .
although we are unable to connect either of these states directly to the superconducting ti surface , we argue that one of them describes the 3d ti surface , while the other differs from it by a bosonic topological phase .
we also discuss the 24 particle pfaffian - antisemion topological order ( which can be connected to the superconducting ti surface ) and demonstrate that it can be realized as a @xmath0 symmetric surface state . .
And you have already written the first three sentences of the full article: three dimensional topological insulators host unusual surface states that can be described in a number of different ways@xcite . in models of free electrons that respect time reversal and charge conservation symmetries which are necessary to describe this phase , the surface is metallic .
the surface electronic structure is comprised of an odd number of 2d dirac cones , which is impossible to realize in a purely 2d system with time reversal invariance .
it is crucial that electrons transform as kramers pairs i.e. time reversal @xmath0 acting twice on electrons gives @xmath4.
Please generate the next two sentences of the article | . other surface terminations of the topological bulk are also interesting . if @xmath0 is broken only at the surface , the metallic edge can be gapped to yield an insulating surface .
the topological bulk properties are revealed in the properties of domain walls between opposite @xmath0 breaking regions on the surface . |
4,889 | Suppose that you have an abstract for a scientific paper: the finite temperature casimir free energy is calculated for a dielectric ball of radius @xmath0 embedded in an infinite medium .
the condition @xmath1 is assumed for the inside / outside regions . both the green function method and the mode summation method are considered , and found to be equivalent . for a dilute medium
we find , assuming a simple `` square '' dispersion relation with an abrupt cutoff at imaginary frequency @xmath2 , the high temperature casimir free energy to be negative and proportional to @xmath3 . also , a physically more realistic dispersion relation involving spatial dispersion is considered , and is shown to lead to comparable results . .
And you have already written the first three sentences of the full article: the casimir effect has in recent years attracted considerable interest . for reviews on this topic see , for example , plunien _ _ et al.__@xcite , mostepanenko and trunov@xcite , and milton @xcite .
the problem has been rather difficult to solve , once curved boundaries are present , because of divergences in the formalism and insufficient contact with experiments . in this paper
we will consider a compact ball of radius a , permittivity @xmath4 and permeability @xmath5 , situated in an infinite medium whose corresponding material constants are @xmath6 and @xmath7.
Please generate the next two sentences of the article | . we shall take @xmath8 [ 1 ] so that the photon velocity is everywhere equal to @xmath9 .
the relativistic condition ( 1 ) was , in the context of the casimir effect , to our knowledge first introduced by brevik and kolbenstvedt @xcite . |
4,890 | Suppose that you have an abstract for a scientific paper: we analyze a sample of 16 absorption systems intrinsic to long duration grb host galaxies at @xmath0 for which the metallicities are known .
we compare the relation between the metallicity and cold gas velocity width for this sample to that of the qso - dlas , and find complete agreement .
we then compare the redshift evolution of the mass - metallicity relation of our sample to that of qso - dlas and find that also grb hosts favour a late onset of this evolution , around a redshift of @xmath1 .
we compute predicted stellar masses for the grb host galaxies using the prescription determined from qso - dla samples and compare the measured stellar masses for the four hosts where stellar masses have been determined from sed fits .
we find excellent agreement and conclude that , on basis of all available data and tests , long duration grb - dla hosts and intervening qso - dlas are consistent with being drawn from the same underlying population .
grb host galaxies and qso - dlas are found to have different impact parameter distributions and we briefly discuss how this may affect statistical samples .
the impact parameter distribution has two effects .
first any metallicity gradient will shift the measured metallicity away from the metallicity in the centre of the galaxy , second the path of the sightline through different parts of the potential well of the dark matter halo will cause different velocity fields to be sampled .
we report evidence suggesting that this second effect may have been detected .
[ firstpage ] galaxies : high - redshift galaxies : ism galaxies : star formation galaxies :
evolution galaxies : formation quasars : absorption lines .
And you have already written the first three sentences of the full article: stellar mass and metallicity are two of the most fundamental physical properties of galaxies .
the metal enrichment of the inter stellar medium ( ism ) of a galaxy is a consequence of supernova explosions and stellar winds and is therefore related to the star formation history ( sfh ) of the galaxy . also , the amount of mass in stars is a function of galaxy sfh .
therefore , understanding the evolution of the two properties and the relation between them is fundamental to understand the formation and evolution of galaxies ..
Please generate the next two sentences of the article | observations have shown that for local and low redshift galaxies a tight relation exists between the galaxy mass and its metallicity ( see e.g. * ? ? ?
* ; * ? ? ? |
4,891 | Suppose that you have an abstract for a scientific paper: we present a fully automatic method for music classification , based only on compression of strings that represent the music pieces .
the method uses no background knowledge about music whatsoever : it is completely general and can , without change , be used in different areas like linguistic classification and genomics .
it is based on an ideal theory of the information content in individual objects ( kolmogorov complexity ) , information distance , and a universal similarity metric .
experiments show that the method distinguishes reasonably well between various musical genres and can even cluster pieces by composer . .
And you have already written the first three sentences of the full article: all musical pieces are similar , but some are more similar than others . apart from being an infinite source of discussion ( `` haydn is just like mozart no , he s not ! '' ) , such similarities are also crucial for the design of efficient music information retrieval systems .
the amount of digitized music available on the internet has grown dramatically in recent years , both in the public domain and on commercial sites .
napster and its clones are prime examples ..
Please generate the next two sentences of the article | websites offering musical content in some form or other ( mp3 , midi , ) need a way to organize their wealth of material ; they need to somehow classify their files according to musical genres and subgenres , putting similar pieces together .
the purpose of such organization is to enable users to navigate to pieces of music they already know and like , but also to give them advice and recommendations ( `` if you like this , you might also like '' ) . |
4,892 | Suppose that you have an abstract for a scientific paper: by performing differential elastoresistivity measurements on a wider range of iron based superconductors , including electron doped ( ba(fe@xmath0co@xmath1)@xmath2as@xmath2 , ba(fe@xmath0ni@xmath1)@xmath2as@xmath2 ) , hole doped ( ba@xmath0k@xmath1fe@xmath2as@xmath2 ) , isovalent substituted pnictides ( bafe@xmath2(as@xmath0p@xmath1)@xmath2 ) and chalcogenides ( fete@xmath0se@xmath1 ) , we show that a divergent nematic susceptibility in the b@xmath3 symmetry channel appears to be a generic feature of optimally doped compositions .
122bafe@xmath2as@xmath2 122cafe@xmath2as@xmath2 122ba(fe@xmath0co@xmath1)@xmath2as@xmath2 122ba@xmath0k@xmath1fe@xmath2as@xmath2 327sr@xmath4ru@xmath2o@xmath5 * a growing body of evidence suggests the possibility of an intimate connection between electronic nematic phases @xcite and high - temperature superconductivity . at the moment it is unclear whether nematicity is an epi - phenomenon , or if there is a more fundamental causal relationship between nematic fluctuations and superconductivity . from an empirical perspective , strongly anisotropic
electronic phases are found in the underdoped regime of both cuprate @xcite and fe - based @xcite high - temperature superconductors .
for underdoped fe - based systems , recent measurements of the elastoresisistance @xcite and elastic moduli @xcite for the representative electron - doped system ba(fe@xmath0co@xmath1)@xmath2as@xmath2 reveal a divergence of the electronic nematic susceptibility upon approach to the tetragonal - to - orthorhombic structural phase transition , definitively establishing that the phase transition is driven by electronic correlation . for the cuprates ,
recent x - ray diffraction @xcite and nmr @xcite measurements have revealed evidence for short - range charge density wave order in `` underdoped '' crystals .
although details of the charge ordered state(s ) are still being established , these initial observations have at least motivated discussion of a possible `` vestigial '' nematic order....
And you have already written the first three sentences of the full article: the authors thank s. raghu , s. lederer for helpful conversations . this work was supported by the doe , office of basic energy sciences , under contract no .
de - ac02 - 76sf00515
. 10 e. fradkin , s. a. kivelson , m. j. lawler , j. p. eisenstein , a. p. mackenzie , nematic fermi fluids in condensed matter physics . _ annu ..
Please generate the next two sentences of the article | rev . condens .
matter phys . _ |
4,893 | Suppose that you have an abstract for a scientific paper: we perform classical molecular dynamics simulations to investigate the mechanical compression effect on the thermal conductivity of the single - walled carbon nanotube ( swcnt ) forest , in which swcnts are closely aligned and parallel with each other .
we find that the thermal conductivity can be linearly enhanced by increasing compression before the buckling of swcnt forests , but the thermal conductivity decreases quickly with further increasing compression after the forest is buckled .
our phonon mode analysis reveals that , before buckling , the smoothness of the inter - tube interface is maintained during compression , and the inter - tube van der waals interaction is strengthened by the compression .
consequently , the twisting - like mode ( good heat carrier ) is well preserved and its group velocity is increased by increasing compression , resulting in the enhancement of the thermal conductivity .
the buckling phenomenon changes the circular cross section of the swcnt into ellipse , which causes effective roughness at the inter - tube interface for the twisting motion . .
And you have already written the first three sentences of the full article: single - walled carbon nanotube ( swcnt ) is a member from the carbon based nano - material family , which is characteristic for superior thermal conductivity.@xcite in many practical applications , the quasi - one - dimensional swcnt is ensembled in a bulk form , such as the swcnt mat ( or buckypaper).@xcite tubes in the swcnt mat are randomly orientated , leading to the lose of swcnt s advanced properties . for instance , the room temperature thermal conductivity in the swcnt mat is typically in the range of @xmath0 to 10 wm@xmath1k@xmath1 , which is several orders lower than the swcnt.@xcite besides the randomly orientated swcnt mat , there is a particular mat structure , with all tubes aligning parallel with each other .
this structure is termed as swcnt forest , or swcnt crystalline .
the vertically aligned swcnt forest has promising practical applications such as supercapacitor electrodes for compact energy - storage devices , since it retains most mechanical , thermal , and electronic properties of the swcnt.@xcite during the development of the swcnt forest , the density used to be a bottleneck for its practical applications , because most advanced properties of the swcnt forest will disappear if its density is too low.@xcite great progress has been achieved in recent years toward the production of dense swcnt forest ..
Please generate the next two sentences of the article | futaba et al .
fabricated a high - density swcnt forest by using the zipping effect of liquids to draw tubes together.@xcite the density of the swcnt forest is increased to @xmath2 @xmath3 by zhong et al . |
4,894 | Suppose that you have an abstract for a scientific paper: in this paper we present the solver duquad specialized for solving general convex quadratic problems arising in many engineering applications .
when it is difficult to project on the primal feasible set , we use the ( augmented ) lagrangian relaxation to handle the complicated constraints and then , we apply dual first order algorithms based on inexact dual gradient information for solving the corresponding dual problem .
the iteration complexity analysis is based on two types of approximate primal solutions : the primal last iterate and an average of primal iterates .
we provide computational complexity estimates on the primal suboptimality and feasibility violation of the generated approximate primal solutions .
then , these algorithms are implemented in the programming language c in duquad , and optimized for low iteration complexity and low memory footprint .
duquad has a dynamic matlab interface which make the process of testing , comparing , and analyzing the algorithms simple .
the algorithms are implemented using only basic arithmetic and logical operations and are suitable to run on low cost hardware .
it is shown that if an approximate solution is sufficient for a given application , there exists problems where some of the implemented algorithms obtain the solution faster than state - of - the - art commercial solvers . .
And you have already written the first three sentences of the full article: nowadays , many engineering applications can be posed as convex quadratic problems ( qp ) .
several important applications that can be modeled in this framework such us model predictive control for a dynamical linear system @xcite and its dual called moving horizon estimation @xcite , dc optimal power flow problem for a power system @xcite , linear inverse problems arising in many branches of science @xcite or network utility maximization problems @xcite have attracted great attention lately . since the computational power has increased by many orders in the last decade ,
highly efficient and reliable numerical optimization algorithms have been developed for solving the optimization problems arising from these applications in very short time ..
Please generate the next two sentences of the article | for example , these hardware and numerical recent advances made it possible to solve linear predictive control problems of nontrivial sizes within the range of microseconds and even on hardware platforms with limited computational power and memory @xcite .
the theoretical foundation of quadratic programming dates back to the work by frank & wolfe @xcite . after the publication of the paper @xcite many numerical algorithms |
4,895 | Suppose that you have an abstract for a scientific paper: recent studies suggest that cooperative decision - making in one - shot interactions is a history - dependent dynamic process : promoting intuition versus deliberation has typically a positive effect on cooperation ( dynamism ) among people living in a cooperative setting and with no previous experience in economic games on cooperation ( history - dependence ) . here
we report on a lab experiment exploring how these findings transfer to a non - cooperative setting .
we find two major results : ( i ) promoting intuition versus deliberation has no effect on cooperative behavior among inexperienced subjects living in a non - cooperative setting ; ( ii ) experienced subjects cooperate more than inexperienced subjects , but only under time pressure .
these results suggest that cooperation is a learning process , rather than an instinctive impulse or a self - controlled choice , and that experience operates primarily via the channel of intuition . in doing so ,
our findings shed further light on the cognitive basis of human cooperative decision - making and provide further support for the recently proposed social heuristics hypothesis .
@xmath0center for mathematics and computer science ( cwi ) , 1098 xg , amsterdam , the netherlands .
@xmath1department of political sciences , luiss guido carli , 00197 , roma , italy .
contact author : [email protected]__forthcoming in proceedings of the royal society b : biological sciences _ _ .
And you have already written the first three sentences of the full article: one of the factors of the enormous success of our societies is our ability to cooperate @xcite . while in most animal species cooperation
is observed only among kin or in very small groups , where future interactions are likely , cooperation among people goes far beyond the five rules of cooperation @xcite : recent experiments have shown that people cooperate also in one - shot anonymous interactions @xcite and even in large groups @xcite .
this poses an evolutionary puzzle : why are people willing to pay costs to help strangers when no future rewards seem to be at stake ?.
Please generate the next two sentences of the article | a growing body of experimental research suggests that cooperative decision - making in one - shot interactions is most likely a history - dependent dynamic process . _
dynamic _ because time pressure @xcite , cognitive load @xcite , conceptual priming of intuition @xcite , and disruption of the right lateral prefrontal cortex @xcite have all been shown to promote cooperation , providing direct evidence that automatic actions are , on average , more cooperative than deliberate actions . |
4,896 | Suppose that you have an abstract for a scientific paper: we consider the problem of estimating the density @xmath0 of identically distributed variables @xmath1 , from a sample @xmath2 where @xmath3 , @xmath4 and @xmath5 is a noise independent of @xmath1 with known density @xmath6 .
we generalize adaptive estimators , constructed by a model selection procedure , described in comte et al .
( 2005 ) .
we study numerically their properties in various contexts and we test their robustness .
comparisons are made with respect to deconvolution kernel estimators , misspecification of errors , dependency , ...
it appears that our estimation algorithm , based on a fast procedure , performs very well in all contexts .
universit paris v , map5 , umr cnrs 8145 . ] iut de paris v et universit dorsay , laboratoire de probabilits , statistique et modlisation , umr 8628 . ]
adaptive estimation
. density deconvolution .
model selection .
penalized contrast .
projection estimator . simulation study .
data - driven . .
And you have already written the first three sentences of the full article: in this paper , we consider the problem of the nonparametric density deconvolution of @xmath0 , the density of identically distributed variables @xmath1 , from a sample @xmath7 in the model @xmath8 where the @xmath1 s and @xmath9 s are independent sequences , the @xmath9 s are i.i.d . centered random variables with common density @xmath10 , that is @xmath11 is a noise with known density @xmath12 and known noise level @xmath13 . due to the independence between the @xmath1 s and the @xmath9 s ,
the problem is to estimate @xmath0 using the observations @xmath14 with common density @xmath15 the function @xmath16 is often called the convolution kernel and is completely known here . denoting by @xmath17 the fourier transform of @xmath18 ,
it is well known that since @xmath19 , two factors determine the estimation accuracy in the standard density deconvolution problem : the smoothness of the density to be estimated , and the one of the error density which are described by the rate of decay of their fourier transforms . in this context ,.
Please generate the next two sentences of the article | two classes of errors are usually considered : first the so called ordinary smooth " errors with polynomial decay of their fourier transform and second , the super smooth " errors with fourier transform having an exponential decay . for further references about density deconvolution see e.g. carroll and hall ( 1988 ) , devroye ( 1989 ) , fan ( 1991a , b ) , liu and taylor ( 1989 ) , masry ( 1991 , 1993a , b ) , stefansky ( 1990 ) , stefansky and carroll ( 1990 ) , taylor and zhang ( 1990 ) , zhang ( 1990 ) and cator ( 2001 ) , pensky and vidakovic ( 1999 ) , pensky ( 2002 ) , fan and koo ( 2002 ) , butucea ( 2004 ) , butucea and tsybakov ( 2004 ) , koo ( 1999 ) . the aim of the present paper is to provide a complete simulation study of the deconvolution estimator constructed by a penalized contrast minimization on a model @xmath20 , a space of square integrable functions having a fourier transform with compact support included into @xmath21 $ ] with @xmath22 .
comte et al . |
4,897 | Suppose that you have an abstract for a scientific paper: we obtain by invariance arguments the relativistic and non - relativistic invariant dynamical equations of a classical model of a spinning electron .
we apply the formalism to a particular classical model which satisfies dirac s equation when quantised .
it is shown that the dynamics can be described in terms of the evolution of the point charge which satisfies a fourth order differential equation or , alternatively , as a system of second order differential equations by describing the evolution of both the center of mass and center of charge of the particle . as an application of the found dynamical equations ,
the coulomb interaction between two spinning electrons is considered .
we find from the classical viewpoint that these spinning electrons can form bound states under suitable initial conditions .
since the classical coulomb interaction of two spinless point electrons does not allow for the existence of bound states , it is the spin structure that gives rise to new physical phenomena not described in the spinless case .
perhaps the paper may be interesting from the mathematical point of view but not from the point of view of physics . .
And you have already written the first three sentences of the full article: wigner defined a quantum elementary particle as a system whose hilbert space of states carries an irreducible representation of the poincar group @xcite .
this definition is a group theoretical one .
this lead the author to look for a definition of a classical elementary particle by group theoretical methods , relating its definition to the kinematical group structure ..
Please generate the next two sentences of the article | a classical elementary particle was defined as a lagrangian system whose kinematical space is a homogeneous space of the poincar group @xcite .
when quantising these classical models it is shown that the wave function of the system transforms with a projective unitary irreducible representation of the kinematical group @xcite . |
4,898 | Suppose that you have an abstract for a scientific paper: in recent years impressive progress has been made in the development of highly accurate energy density functionals , which allow to treat medium - heavy nuclei . in this approach one
tries to describe not only the ground state but also the first relevant excited states . in general
, higher accuracy requires a larger set of parameters , which must be carefully chosen to avoid redundancy . following this line of development , it is unavoidable that the connection of the functional with the bare nucleon - nucleon interaction becomes more and more elusive . in principle
, the construction of a density functional from a density matrix expansion based on the effective nucleon - nucleon interaction is possible , and indeed the approach has been followed by few authors .
however , to what extent a density functional based on such a microscopic approach can reach the accuracy of the fully phenomenological ones remains an open question .
a related question is to establish which part of a functional can be actually derived by a microscopic approach and which part , on the contrary , must be left as purely phenomenological . in this paper
we discuss the main problems that are encountered when the microscopic approach is followed . to this purpose
we will use the method we have recently introduced to illustrate the different aspects of these problems .
in particular we will discuss the possible connection of the density functional with the nuclear matter equation of state and the distinct features of finite size effects proper of nuclei . .
And you have already written the first three sentences of the full article: the microscopic calculation of ground state energy and particle density of medium and heavy nuclei based on realistic nucleon - nucleon interaction requires the solution of a formidable many - body problem . for this reason
effective nucleon - nucleon interactions have been introduced , like the skyrme @xcite and gogny @xcite forces .
they simplify enormously the problem since , by construction , they must be used at the mean field level , and the calculation of the mean single particle potential and of the ground state energy becomes easily manageable ..
Please generate the next two sentences of the article | the number of parameters which enter these effective forces is typically around ten and they are adjusted to reproduce finite nuclei and some equilibrium nuclear matter properties .
however , recently also data from a theoretically determined neutron matter equation of state ( eos ) @xcite have been used as input ( see also an older attempt in this direction in @xcite ) . |
4,899 | Suppose that you have an abstract for a scientific paper: in this review , we develop the formalism employed to describe charge - density - wave insulators in pump / probe experiments using ultra short driving pulses of light . the theory emphasizes exact results in the simplest model for a charge - density wave insulator ( given by a noninteracting systems with two bands and a gap ) and by employing nonequilibrium dynamical mean - field theory to solve the falicov - kimball model in its ordered phase .
we show both how to develop the formalism and how the solutions behave .
care is taken to describe the details behind these calculations and to show how to verify their accuracy via sum - rule constraints .
_ keywords _ : pump / probe experiment , charge - density - wave insulator , time - resolved photoemission spectroscopy , nonequilibrium dynamical mean - field theory .
And you have already written the first three sentences of the full article: time - resolved pump / probe experiments have seen a rebirth in recent years as timescales have been pushed well into the femtosecond ( and sometimes attosecond ) range , and as many different types of experiments can now be performed in an ultrafast pump / probe format .
much of the experimental work , ranging from ultrafast optical studies to angle - resolved photoemission ( arpes ) have been centered on examining the behavior of charge density wave materials @xcite . in this paper
, we will review work on theoretical descriptions of pump / probe time - resolved photoemission spectroscopy on charge - density - wave ( cdw ) materials ..
Please generate the next two sentences of the article | because this is a short review , we will focus entirely on our work , which describes many of the experimental features seen in recent studies .
pump / probe photoemission experiments really came to life when it was recognized that one could period quadruple a 1.5 ev light pulse to create 6 ev pulses that also are ultrashort ( typical widths are in the few 10s of femtoseconds ) . |
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