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7,200 | Suppose that you have an abstract for a scientific paper: the self - gravitating gas in the presence of a positive cosmological constant @xmath0 is studied in thermal equilibrium by monte carlo simulations and by the mean field approach .
we find excellent agreement between both approaches already for @xmath1 particles on a volume @xmath2 [ the mean field is exact in the infinite @xmath3 limit ] .
the domain of stability of the gas is found to increase when the cosmological constant increases .
the particle density is shown to be an increasing ( decreasing ) function of the distance when the dark energy dominates over self - gravity ( and vice - versa ) .
we confirm the validity of the thermodynamic limit : @xmath4 with @xmath5 and @xmath6 fixed . in such dilute limit extensive thermodynamic quantities like energy , free energy , entropy turn to be proportional to @xmath3 .
we find that the gas is stable till the isothermal compressibility diverges . beyond this point
the gas becomes a extremely dense object whose properties are studied by monte carlo . .
And you have already written the first three sentences of the full article: the self - gravitating gas in thermal equilibrium has been thoroughly studied since many years@xcite . as a consequence of the long range attractive newton force
, the selfgravitating gas admits a consistent thermodynamic limit @xmath4 with @xmath7 fixed . in this limit , extensive thermodynamic quantities like energy , free energy , entropy are proportional to @xmath3@xcite .
in ref.@xcite we investigated how a cosmological constant affects the properties of the non - relativistic self - gravitating gas in thermal equilibrium by mean field methods ..
Please generate the next two sentences of the article | the mean field approximation becomes exact in the limit when the number of particles becomes infinity . in the present paper
we study the stability properties of the self - gravitating gas in the presence of a cosmological constant by mean field and monte - carlo methods . |
7,201 | Suppose that you have an abstract for a scientific paper: observations of high - redshift supernovae ( sne ) open a novel opportunity to study the massive star population in the early universe .
we study the detectability of superluminous sne with upcoming optical and near - infrared ( nir ) surveys .
our calculations are based on the cosmic star formation history , the sn occurence rate , the characteristic colour and the light curve of the sne that are all calibrated by available observations .
we show that 15 - 150 sne up to @xmath0 will be discovered by the proposed subaru / hyper suprime - cam deep survey : 30 deg@xmath1 survey with 24.5 ab mag depth in @xmath2-band for 3 months . with its ultra - deep layer ( 3.5 deg@xmath1 with 25.6 ab mag depth in @xmath2-band for 4 months )
, the highest redshift can be extended to @xmath3 .
we further explore the detectability by upcoming nir survey utilizing future satellites such as euclid , wfirst , and wish .
the wide - field nir surveys are very efficient to detect high - redshift sne . with a hypothetical deep nir survey for 100 deg@xmath1 with 26 ab mag depth at 1 - 4 @xmath4 m ,
at least @xmath5 50 sne will be discovered at @xmath6 in half a year .
the number of the detected sne can place a strong constraint on the stellar initial mass function or its slope especially at the high - mass end .
superluminous sne at high redshifts can be distinguished from other types of sne by the long time - scale of their light curves in the observer s frame , the optical colours redder than other core - collapse sne and the nir colours redder than any other types of sne .
[ firstpage ] stars : luminosity function , mass function
supernovae : general early universe .
And you have already written the first three sentences of the full article: core - collapse supernovae ( sne ) are triggered by massive stars at the end of their lives .
thanks to the high luminosity , sne can be detected in distant galaxies . by measuring the cosmic occurrence rate of core - collapse sne , one can study the overall formation rate of the massive star population through cosmic time .
with upcoming or planned large - scale optical and near - infrared ( nir ) surveys , sne could be detected to @xmath7 or higher ..
Please generate the next two sentences of the article | it is thus important to derive a realistic estimate for the detectability in order to make an efficient survey strategy for such observational programmes .
@xcite study the detectability of core - collapse sne with the _ large synoptic survey telescope _ |
7,202 | Suppose that you have an abstract for a scientific paper: community detection in networks is one of the most popular topics of modern network science .
communities , or clusters , are usually groups of vertices having higher probability of being connected to each other than to members of other groups , though other patterns are possible . identifying communities is an ill - defined problem .
there are no universal protocols on the fundamental ingredients , like the definition of community itself , nor on other crucial issues , like the validation of algorithms and the comparison of their performances .
this has generated a number of confusions and misconceptions , which undermine the progress in the field .
we offer a guided tour through the main aspects of the problem .
we also point out strengths and weaknesses of popular methods , and give directions to their use . .
And you have already written the first three sentences of the full article: the science of networks is a modern discipline spanning the natural , social and computer sciences , as well as engineering @xcite .
networks , or graphs , consist of _ vertices _ and _ edges_. an edge typically connects a pair of vertices .
networks occur in an huge variety of contexts ..
Please generate the next two sentences of the article | facebook , for instance , is a large social network , where more than one billion people are connected via virtual acquaintanceships .
another famous example is the internet , the physical network of computers , routers and modems which are linked via cables or wireless signals ( fig . |
7,203 | Suppose that you have an abstract for a scientific paper: it is common practice in statistical data analysis to perform data - driven variable selection and derive statistical inference from the resulting model .
such inference enjoys none of the guarantees that classical statistical theory provides for tests and confidence intervals when the model has been chosen a priori .
we propose to produce valid `` post - selection inference '' by reducing the problem to one of simultaneous inference and hence suitably widening conventional confidence and retention intervals .
simultaneity is required for all linear functions that arise as coefficient estimates in all submodels . by purchasing `` simultaneity insurance '' for all possible submodels ,
the resulting post - selection inference is rendered universally valid under all possible model selection procedures .
this inference is therefore generally conservative for particular selection procedures , but it is always less conservative than full scheff protection .
importantly it does _ not _ depend on the truth of the selected submodel , and hence it produces valid inference even in wrong models .
we describe the structure of the simultaneous inference problem and give some asymptotic results . , , , + .
And you have already written the first three sentences of the full article: classical statistical theory grants validity of statistical tests and confidence intervals assuming a wall of separation between the selection of a model and the analysis of the data being modeled . in practice , this separation rarely exists , and more often a model is `` found '' by a data - driven selection process . as a consequence inferential guarantees derived from classical theory are invalidated . among model selection methods that are problematic for classical inference , _ variable selection _ stands out because it is regularly taught , commonly practiced and highly researched as a technology .
even though statisticians may have a general awareness that the data - driven selection of variables ( predictors , covariates ) must somehow affect subsequent classical inference from @xmath0- and @xmath1-based tests and confidence intervals , the practice is so pervasive that it appears in classical undergraduate textbooks on statistics such as @xcite .
the reason for the invalidation of classical inference guarantees is that a data - driven variable selection process produces a model that is itself stochastic , and this stochastic aspect is not accounted for by classical theory ..
Please generate the next two sentences of the article | models become stochastic when the stochastic component of the data is involved in the selection process .
( in regression with fixed predictors the stochastic component is the response . ) |
7,204 | Suppose that you have an abstract for a scientific paper: we determine which three - manifolds are dominated by products .
the result is that a closed , oriented , connected three - manifold is dominated by a product if and only if it is finitely covered either by a product or by a connected sum of copies of @xmath0 .
this characterization can also be formulated in terms of thurston geometries , or in terms of purely algebraic properties of the fundamental group .
we also determine which three - manifolds are dominated by non - trivial circle bundles , and which three - manifold groups are presentable by products . .
And you have already written the first three sentences of the full article: the study of non - zero degree maps between closed , oriented manifolds has become very active over the last few decades @xcite .
the existence of a non - zero degree map , @xmath1 , defines a transitive relation on the set of homotopy types of closed , oriented manifolds .
whenever such a map exists we say that @xmath2 dominates @xmath3 and write @xmath4 . in this case.
Please generate the next two sentences of the article | @xmath2 is at least as complicated as @xmath3 .
for example , the induced maps in rational homology are surjective , thus , in particular , the betti numbers of @xmath3 are bounded from above by those of @xmath2 . |
7,205 | Suppose that you have an abstract for a scientific paper: the time - dependent optical properties of molecular systems are investigated by step - scan fourier - transform spectroscopy in order to explore the dynamics at phase transitions and molecular orientation in the milli- and microsecond range .
the electrical switching of liquid crystals traced by vibrational spectroscopy reveals a rotation of the molecules with a relaxation time of 2 ms .
the photo - induced neutral - ionic transition in ttf - ca takes place by a suppression of the dimerization in the ionic phase and creation of neutral domains .
the time - dependent infrared spectra depend on temperature and laser pulse intensity ; the relaxation of the spectra follows a stretched - exponential decay with relaxation times in the microsecond range strongly dependent on temperature and laser intensity .
we present all details of the experimental setups and thoroughly discuss the technical challenges .
example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave .4 setgray fill grestore stroke grestore .
And you have already written the first three sentences of the full article: fourier - transform infrared ( ftir ) spectroscopy is a widely utilized method to investigate the optical response of gasses , liquids and solids @xcite . in general ,
steady - state properties are measured , however , numerous approaches have been developed over the years to explore time - dependent phenomena by fourier - transform interferometry @xcite , many of them optimized for a certain time regime .
standard rapid - scan techniques are limited by the mirror velocity to a fraction of a second ( typically 10 ms ) , depending on the spectral resolution @xmath0 required : @xmath1 . since this is often not sufficient , step - scanning.
Please generate the next two sentences of the article | is nowadays implemented in several high - end commercial fourier - transform instruments because there is no inherent time limit .
it covers the largest dynamical range with a time resolution of the order of nanoseconds determined by the current detector and electronics technology @xcite and still achieving a high spectral resolution @xmath2 . |
7,206 | Suppose that you have an abstract for a scientific paper: nuclear chirality has been intensively studdied for the last several years in the context of experimental as well as theoretical approach .
characteristic gamma selection rules have been predicted for the strong chiral symmetry breaking limit that has been observed in cs isotopes .
the presented analysis shows that the gamma selection rules can not be attributed only to chiral symmetry breaking .
the selection rules relate to structural composition of the chiral rotational bands , i.e. to odd particle configuration and the deformation of the core . .
And you have already written the first three sentences of the full article: chirality in nuclear physics relates to features of nuclear hamiltonian in the context of time reversal symmetry .
the phenomenon of explicit time - reversal symmetry breaking comes up through already well known cabibbo - kobayashi - maskawa matrix of the standard model .
the ckm matrix , introduced in order to diagonalize the mass terms given by higgs mechanism with respect to quark flavor , contains t violating terms being associated with the heavy quark sector ..
Please generate the next two sentences of the article | therefore no explicit t violation is expected to be present in low energy nuclear interactions giving t - symmetric nuclear hamiltonian .
what remains is the mechanism of spontaneous time reversal symmetry breaking and possible occurrence of spontaneous breakdown of the chiral symmetry . |
7,207 | Suppose that you have an abstract for a scientific paper: models of tumor growth , now commonly used , present several levels of complexity , both in terms of the biomedical ingredients and the mathematical description .
the simplest ones contain competition for space using purely fluid mechanical concepts .
another possible ingredient is the supply of nutrients through vasculature .
the models can describe the tissue either at the level of cell densities , or at the scale of the solid tumor , in this latter case by means of a free boundary problem .
our first goal here is to formulate a free boundary model of hele - shaw type , a variant including growth terms , starting from the description at the cell level and passing to a certain limit .
a detailed mathematical analysis of this purely mechanical model is performed .
indeed , we are able to prove strong convergence in passing to the limit , with various uniform gradient estimates ; we also prove uniqueness for the asymptotic hele - shaw type problem .
the main tools are nonlinear regularizing effects for certain porous medium type equations , regularization techniques la steklov , and a hilbert duality method for uniqueness . at variance with the classical hele - shaw problem , here
the geometric motion governed by the pressure is not sufficient to completely describe the dynamics .
a complete description requires the equation on the cell number density . using this theory as a basis , we go on to consider the more complex model including nutrients .
we obtain the equation for the limit of the coupled system ; the method relies on some bv bounds and space / time a priori estimates
. here , new technical difficulties appear , and they reduce the generality of the results in terms of the initial data . finally , we prove uniqueness for the system , a main mathematical difficulty . *
key words * tumor growth ; hele - shaw equation ; free boundary problems ; porous media ; hilbert uniqueness method .
* mathematics subject classification * 35k55 ; 35b25 ; 76d27 ; 92c50 . .
And you have already written the first three sentences of the full article: in the understanding of cancer development , mathematical modeling and numerical simulations have nowadays complemented experimental and clinical observations .
the field is now mature ; books and surveys are available , as for example @xcite .
a first class of models , initiated in the 70 s by greenspan @xcite , has considered that cancerous cells multiplication is limited by nutrients ( glucosis , oxygen ) brought by blood vessels ..
Please generate the next two sentences of the article | models of this class rely on two kinds of descriptions ; either they describe the dynamics of cell population density @xcite or they consider the geometric motion of the tumor through a free boundary problem ; see and the references therein .
this stage lasts until the tumor reaches the size of @xmath0 mm ; then lack of nutrients leads to cell necrosis which triggers neovasculatures development @xcite that supply the tumor with enough nourishment . |
7,208 | Suppose that you have an abstract for a scientific paper: we report timing and spectral properties of the transient be x - ray pulsar exo 0531096609.2 studied using observations made with the asca and beppo - sax observatories . though there must have been at least one spin - down episode of the pulsar since its discovery
, the new pulse period measurements show a monotonic spin - up trend since 1996 . the pulse profile is found to have marginal energy dependence .
there is also evidence for strong luminosity dependence of the pulse profile , a single peaked profile at low luminosity that changes to a double peaked profile at high luminosity .
this suggests a change in the accretion pattern at certain luminosity level .
the x - ray spectrum is found to consist of a simple power - law with photon index in the range of 0.40.8 . at high intensity level
the spectrum also shows presence of weak iron emission line . .
And you have already written the first three sentences of the full article: the two magellanic clouds have larger number density of high mass x - ray binaries ( hmxb ) compared to our galaxy .
the small magellanic cloud ( smc ) with a mass of about 1% of our galaxy has a total of about 70 hmxbs and hmxb candidates , almost comparable to that in our galaxy ( haberl & sasaki 2000 ; yokogawa et al .
though the hmxb number density in the large magellanic cloud ( lmc ) is not as high as that in smc , it is still significantly higher than the galactic value ( sasaki , haberl & pietsch 2000 ) . in - spite of a large number of hmxb pulsar objects in the two magellanic clouds , individual objects have not been studied in great detail except for smc x-1 and lmc x-4.
Please generate the next two sentences of the article | there are four hmxb pulsars known in the lmc , of which lmc x-4 is the best studied .
several of these sources show a very large x - ray luminosity in their high states , close to or exceeding the eddington limit for a 1 m@xmath0 object . |
7,209 | Suppose that you have an abstract for a scientific paper: understanding light - matter interactions using localized surface plasmons ( lsps ) is of fundamental interest in classical and quantum plasmonics and has a wide range of applications . in order to understand the spatial properties of lsps , electron energy loss spectroscopy ( eels )
is a common and powerful method of spatially resolving the extreme localized fields that can be obtained with metal resonators .
however , modelling eels for general shaped resonators presents a major challenge in computational electrodynamics , requiring the full photon green function as a function of two space points and frequency . here
we present an intuitive and computationally simple method for computing eels maps of plasmonic resonators using a quasinormal mode ( qnm ) expansion technique . by separating the contribution of the qnm and the bulk material , we give closed - form analytical formulas for the plasmonic qnm contribution to the eels maps .
we exemplify our technique for a split ring resonator , a gold nanorod , and a nanorod dimer structure .
the method is accurate , intuitive , and gives orders of magnitude improvements over direct dipole simulations that numerically solve the full 3d maxwell equations .
we also show how the same qnm green function can be used to obtain the purcell factor ( and projected local density of optical states ) from quantum dipole emitters or two level atoms , and we demonstrate how the spectral features differ in general to the eels spectrum . .
And you have already written the first three sentences of the full article: nanoplasmonics continues to receive substantial interest from various fields of research including biology @xcite , chemistry @xcite and physics @xcite , with applications ranging from renewable energy technology @xcite to homeland security by the sensitive identification of explosive material @xcite . due to the collective excitations of electrons at the surface of a metallic resonator coupling to electromagnetic fields
, the local density of optical states ( ldos ) decreases rapidly for spatial positions away from the surface of the metal resonator ; so - called `` hot spots '' , where the local electric field can be enhanced by orders of magnitude in comparison to a bulk medium , are formed near the surface .
the unique properties of localized surface plasmon ( lsp ) resonances , manifest in a strong confinement of electric field far below the diffraction limit and result in an exotic electromagnetic response that underlines the wide application of surface plasmons , especially in nanoscience and nanophotonics ; however , the extreme spatial localization of lsps makes them experimentally challenging for direct detection of the spatial field distribution , e.g. , by employing conventional spectroscopy techniques , since the spatial resolution is constrained by the diffraction limit ..
Please generate the next two sentences of the article | in addition , optically dark modes have a vanishing dipole moment , and traditional optical methods fail to excite such modes . due to the strong frequency dispersion and losses in metals , which satisfy the kramers - kronig relations , it is a very challenging problem to model the electromagnetic response of arbitrarily shaped metal resonators .
consequently , most optical studies of plasmonic structures rely heavily on brute force numerical simulations . |
7,210 | Suppose that you have an abstract for a scientific paper: we consider a variant of two - point euclidean shortest path query problem : given a polygonal domain , build a data structure for two - point shortest path query , provided that query points always lie on the boundary of the domain . as a main result
, we show that a logarithmic - time query for shortest paths between boundary points can be performed using @xmath0 preprocessing time and @xmath0 space where @xmath1 is the number of corners of the polygonal domain and the @xmath2-notation suppresses the polylogarithmic factor .
this is realized by observing a connection between davenport - schinzel sequences and our problem in the parameterized space .
we also provide a tradeoff between space and query time ; a sublinear time query is possible using @xmath3 space .
our approach also extends to the case where query points should lie on a given set of line segments . .
And you have already written the first three sentences of the full article: a polygonal domains @xmath4 with @xmath1 corners and @xmath5 holes is a polygonal region of genus @xmath5 whose boundary consists of @xmath1 line segments . the holes and the outer boundary of @xmath4 are regarded as _
obstacles_. then , the geodesic distance between any two points @xmath6 in a given polygonal domain @xmath4 is defined to be the length of a shortest obstacle - avoiding path between @xmath7 and @xmath8 .
the euclidean shortest path problem in a polygonal domain has drawn much attention in the history of computational geometry @xcite . in the _ two - point shortest path query _ problem , we preprocess @xmath4 so that we can determine a shortest path ( or its length ) quickly for a given pair of query points @xmath9 . while we can compute a shortest path in @xmath10 time from scratch @xcite , known structures for logarithmic time query require significantly large storage @xcite ..
Please generate the next two sentences of the article | chiang and mitchell @xcite developed several data structures that can answer a two - point query quickly with tradeoffs between storage usage and query time .
most notably , @xmath11 query time can be achieved by using @xmath12 space and preprocessing time ; sublinear query time by @xmath13 space and preprocessing time . |
7,211 | Suppose that you have an abstract for a scientific paper: halo clouds have been found about the three largest galaxies of the local group and in the halos of nearby spirals .
this suggests they are a relatively generic feature of the galaxy evolution process and a source of fuel for galaxy disks . in this review ,
two main sources of disk star formation fuel , satellite material and clouds condensing from the hot halo medium , are discussed and their contribution to fueling the galaxy quantified .
the origin of the halo gas of m31 and m33 is also discussed . .
And you have already written the first three sentences of the full article: beautiful stellar disks only come to be with the accretion of gaseous clouds of star formation fuel .
there are several reasons why this fuel is thought to be gradually accreted from a galaxy s halo .
the first is that halo gas exists around our galaxy and other spiral galaxies ( e.g. , oort 1970 ; thilker et al ..
Please generate the next two sentences of the article | 2004 ; oosterloo , fraternali & sancisi 2007 ) .
halo gas therefore appears to be a relatively common phenomenon and the gas velocities indicate it will not escape from the galaxy , but rather eventually fall towards the disk . |
7,212 | Suppose that you have an abstract for a scientific paper: we report a survey for molecular gas in nearby powerful radio galaxies .
eight of the eighteen radio galaxies observed were detected with molecular masses in the range @xmath0@xmath1 , similar to the same survey we performed towards 3c radio galaxies .
the upper limits of molecular gas in the remainder are typically of @xmath2 , indicating that very few radiogalaxies have molecular gas reservoir with more than 10@xmath3 . .
And you have already written the first three sentences of the full article: powerful classical double - lobed radio galaxies are ( at low redshifts ) hosted almost exclusively by luminous early - type galaxies .
these galaxies are usually elliptical galaxies . given that normal elliptical galaxies usually exhibit undetectable quantities of cool ( neutral ) gas , what fuels the central supermassive black holes in elliptical radio galaxies ?
our @xmath4co survey of a complete sample of 3c galaxies at low redshift ( lim et al ..
Please generate the next two sentences of the article | , this volume ) reveals that the vast majority have 5@xmath5 upper limits in molecular gas masses of 2 - 5 x 10@xmath6 ( for a linewidth of 500 km / s and a galactic co - to - h@xmath7 conversion factor ) . to better understand the molecular gas content of classical radio galaxies
, we are undertaking a survey of nearby early - type powerful radio galaxies . |
7,213 | Suppose that you have an abstract for a scientific paper: we study the thermodynamics of the asymptotically flat static black hole in lovelock back ground where the coupling constants of the lovelock theory effects are taken into account .
we consider the effects of the second order of the coupling constant , and third order of the lovelock constant coefficient on the thermodynamics of asymptotically flat static black holes . in this case
the effect of the coupling constants on the thermodynamics of the black hole are discussed for 5 , 6 , and 7 dimensional spacetime .
example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave .4 setgray fill grestore stroke grestore .
And you have already written the first three sentences of the full article: one of the possible solutions to the hierarchy problem , is a class of models in which extra spatial dimensions @xcite give rise to strong gravity due to the fact that in @xmath0 dimensions the fundamental planck mass ( md ) can be as low as few tev .
the most significant consequence of the low - scale gravity , is the possibility of production of the tev - scale black holes in particle colliers , such as large hadron collier ( lhc ) @xcite and the available energy must be well above the fundamental planck scale @xcite . in string theory , in addition to einstein - hilbert term , there are higher curvature corrections @xcite . on the other hand ,
higher dimensional black holes have been used to analyzed strongly coupled finite temperature field theories ..
Please generate the next two sentences of the article | so , extension of einstein gravitational theory into those with higher power of curvature in higher dimensions is natural . in this
regards , the lovelock theory of gravity is a candidate belonging to such class of theories @xcite which had received a lot of attention , in particular , in the brane world scenario , low energy string theory , and black hole thermodynamics . since the thermodynamic property of black hole is essentially a quantum feature of gravity , it is expected to gain some insights into quantum gravity in the field of black hole thermodynamics . in this case , the effective action proposed by lovelock @xcite contains the higher powers of curvature in particular combinations and the only produced field equations are the second order one which consequently arise no ghosts @xcite . in this case , the action is precisely of the form @xmath1 where @xmath2 denotes the corresponding lagrangian . + here , |
7,214 | Suppose that you have an abstract for a scientific paper: the extended dynamical mean field theory has played an important role in the study of quantum phase transitions in heavy fermion systems . in order to incorporate the physics of unconventional superconductivity
, we develop a cluster version of the extended dynamical mean field theory . in this approach ,
we show how magnetic order and superconductivity develop as a result of inter - site spin exchange interactions , and analyze in some detail the form of correlation functions .
we also discuss the methods that can be used to solve the dynamical equations associated with this approach . finally , we consider different settings in which our approach can be applied , including the periodic anderson model for heavy fermion systems . .
And you have already written the first three sentences of the full article: unconventional superconductivity in heavy fermion metals often develops in the vicinity of antiferromagnetic ( af ) order@xcite .
its understanding is intimately connected with that of the af quantum critical points ( qcps ) @xcite .
traditional descriptions of heavy fermion quantum criticality are based on those for purely itinerant magnetism , in terms of the fluctuations of the spin - density - wave ( sdw ) order parameter @xcite ..
Please generate the next two sentences of the article | studies in the recent past have emphasized the beyond landau " physics of kondo destruction @xcite . in these studies ,
considerable progress has been made based on the extended dynamical mean field theory ( edmft ) solution of kondo lattice models @xcite . |
7,215 | Suppose that you have an abstract for a scientific paper: we present a theoretical study of vacuum - induced coherence in a pair of vertically stacked semiconductor quantum dots .
the process consists in a coherent excitation transfer from a single - exciton state localized in one dot to a delocalized state in which the exciton occupation gets trapped .
we study the influence of the factors characteristic of quantum dot systems ( as opposed to natural atoms ) : energy mismatch , coupling between the single exciton states localized in different dots , different and non - parallel dipoles due to subband mixing , as well as coupling to phonons .
we show that the destructive effect of the energy mismatch can be overcome by an appropriate interplay of the dipole moments and coupling between the dots which allows one to observe the trapping effect even in a structure with technologically realistic energy splitting on the order of milli - electron - volts .
we also analyze the impact of phonon dynamics on the occupation trapping and show that phonon effects are suppressed in a certain range of system parameters .
this analysis shows that the vacuum induced coherence effect and the associated long - living trapped excitonic population can be achieved in quantum dots . .
And you have already written the first three sentences of the full article: pairs of closely stacked quantum dots ( qds ) coupled via inter - band dipole moments @xcite ( double quantum dots , dqds ) or by tunneling resulting from carrier wave function overlap and coulomb correlations @xcite ( quantum dot molecules , qdms ) attract much attention due to the richness of their physical properties which show huge technological promise for nanoelectronics , spintronics and quantum information processing applications .
the unique features of these systems , as compared to individual qds , can be used as the basis for long - time storage of quantum information @xcite and conditional optical control of carrier states @xcite which pave the way to an implementation of a two - qubit quantum gate @xcite .
double dot structures enable also coherent optical spin control and entangling @xcite or may act as sources of entangled photons @xcite ..
Please generate the next two sentences of the article | it has been shown that the exciton spectrum of a qdm can be used to define an excitonic qubit with an extended life time @xcite , that information can be written on the spin state of the dopant mn ion located in one of the dots forming a dqd @xcite , and that a photon emitted by a nearby quantum point contact may induce carrier transfer in a dqd system @xcite .
the richness and complexity of the physical properties of these systems have been manifested in many optical experiments @xcite . |
7,216 | Suppose that you have an abstract for a scientific paper: an overview is given of the neutrino physics potential of future muon storage rings that use muon collider technology to produce , accelerate and store large currents of muons . .
And you have already written the first three sentences of the full article: this paper gives an overview of the neutrino physics possibilities at a future muon storage ring , which can be either a muon collider ring or a ring dedicated to neutrino physics that uses muon collider technology to store large muon currents .
it summarizes a previous more detailed description of these topics by this author @xcite . after a general characterization of the neutrino beam and its interactions ,
some crude quantitative estimates are given for the physics performance of a muon ring neutrino experiment ( murine ) consisting of a high rate , high performance neutrino detector at a 250 gev muon collider storage ring ..
Please generate the next two sentences of the article | neutrinos are emitted from the decay of muons in the collider ring : @xmath0 the thin pencil beams of neutrinos for experiments will be produced from long straight sections in either the collider ring or a ring dedicated to neutrino physics . from relativistic kinematics , the forward hemisphere in the muon rest frame will be boosted , in the lab frame , into a narrow cone with a characteristic opening half - angle , @xmath1 , given in obvious notation by @xmath2 the large muon currents and tight collimation of the neutrinos results in extremely intense beams intense enough even to constitute a potential off - site radiation hazard @xcite .
for the example of 250 gev muons , the neutrino beam will have an opening half - angle of approximately 0.4 mrad . |
7,217 | Suppose that you have an abstract for a scientific paper: sharp upper bounds for the first eigenvalue of the laplacian on a surface of a fixed area are known only in genera zero and one .
we investigate the genus two case and conjecture that the first eigenvalue is maximized on a singular surface which is realized as a double branched covering over a sphere .
the six ramification points are chosen in such a way that this surface has a complex structure of the bolza surface .
we prove that our conjecture follows from a lower bound on the first eigenvalue of a certain mixed dirichlet - neumann boundary value problem on a half - disk .
the latter can be studied numerically , and we present conclusive evidence supporting the conjecture .
laplacian , first eigenvalue , surface of genus two , mixed boundary value problem . .
And you have already written the first three sentences of the full article: let @xmath0 be a closed surface of genus @xmath1 and let @xmath2 be the riemannian metric on @xmath0 . denote by @xmath3 the laplace - beltrami operator on @xmath0 , and by @xmath4 the smallest positive eigenvalue of the laplacian . let the area @xmath5 be fixed .
how large can @xmath4 be on such a surface ?
sharp bounds for the first eigenvalue are known only for the sphere ( @xcite , see also @xcite ) , the projective plane ( @xcite ) , the torus ( @xcite , @xcite ) , and the klein bottle ( @xcite , @xcite ) ..
Please generate the next two sentences of the article | the present paper is concerned with the surface of genus @xmath6 .
let @xmath0 be orientable and let @xmath7 be a non - constant holomorphic map ( or , conformal branched covering ) of degree @xmath8 . |
7,218 | Suppose that you have an abstract for a scientific paper: after reviewing the basic physics of x - ray reflection in agn , we present three case studies which illustrate the current state of x - ray reflection studies . for the low - luminosity agn ngc 4258 , we find that the iron line is much narrower than is typically found in higher luminosity agn .
we argue that this is evidence for either a truncated cold accretion disk ( possibly due to a transition to an advection dominate accretion flow at @xmath0 ) or a large ( @xmath1 ) x - ray emitting corona surrounding the accretion disk .
we also present results for the higher luminosity seyfert nuclei in ngc 5548 and mcg6 - 30 - 15 . in both of these sources ,
_ rxte _ shows that the iron line equivalent width decreases with increasing luminosity .
furthermore , the iron line equivalent width is found to be _ anticorrelated _ with the relative strength of the reflection continuum , contrary to all simple reflection models .
it is proposed that continuum - flux correlated changes in the ionization of the accretion disk surface can explain this spectral variability .
finally , we address the issue of x - ray iron line reverberation in the light of these complicating factors .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: agn are observed to be copious x - ray emitters .
these x - rays are thought to originate from the innermost regions of an accretion disk around a central supermassive black hole .
since the accretion disk itself is expected to be an optical / uv emitter , the most likely mechanism producing the x - rays is inverse compton scattering of these soft photons in a hot and tenuous corona that sandwiches the accretion disk ..
Please generate the next two sentences of the article | thus , in principle , the study of these x - rays should allow the immediate environment of the accreting black hole as well as the exotic physics , including strong - field general relativity , that operates in this environment to be probed . in the past decade
, x - ray astronomy has begun to fulfill that promise . |
7,219 | Suppose that you have an abstract for a scientific paper: spectroscopy with the keck ii 10-meter telescope and echelle spectrograph and imager is presented for six virgo cluster dwarf elliptical ( de ) galaxies in the absolute magnitude range @xmath0 .
the mean line - of - sight velocity and velocity dispersion are resolved as a function of radius along the major axis of each galaxy , nearly doubling the total number of des with spatially - resolved stellar kinematics .
none of the observed objects shows evidence of strong rotation : upper limits on @xmath1 , the ratio of the maximum rotational velocity to the mean velocity dispersion , are well below those expected for rotationally - flattened objects .
such limits place strong constraints on de galaxy formation models .
although these galaxies continue the trend of low rotation velocities observed in local group des , they are in contrast to recent observations of large rotation velocities in slightly brighter cluster des . using surface photometry from _ hubble space telescope _ wide field planetary camera 2 images and spherically - symmetric dynamical models , we determine global mass - to - light ratios @xmath2 .
these ratios are comparable to those expected for an old to intermediate - age stellar population and are broadly consistent with the observed @xmath3 colors of the galaxies .
these de galaxies therefore do not require a significant dark matter component inside an effective radius .
we are able to rule out central black holes more massive than @xmath4 .
for the five nucleated des in our sample , kinematic and photometric properties were determined for the central nucleus separately from the underlying host de galaxy .
these nuclei are as bright or brighter than the most luminous galactic globular clusters and lie near the region of fundamental plane space occupied by globular clusters . in this space ,
the virgo de galaxies lie in the same general region as local group and other nearby des , although non - rotating des appear to have a slightly higher mean mass and mass - to -....
And you have already written the first three sentences of the full article: dwarf elliptical galaxies ( des ) are the most common galaxy type by number in the local universe , dominating the galaxy luminosity function of nearby clusters . yet
these galaxies remain among the most poorly studied galaxies due to their faint luminosities , @xmath5 , and characteristic low effective surface brightness @xmath6 mag arcsec@xmath7 @xcite . unlike brighter , classical elliptical galaxies whose surface brightness profiles are well fit by the de vaucouleurs @xmath8 law @xcite , des have brightness profiles that are characterized by sersic profiles @xcite with indices ranging between @xmath93 ( where @xmath9 corresponds to an exponential law and @xmath10 to an @xmath8 law ) making them appear more diffuse than classical ellipticals of the same total magnitude @xcite . in the virgo cluster ,
the majority of des brighter than @xmath11 contain compact central nuclei ; fainter than @xmath12 most des show no sign of a nucleus @xcite ..
Please generate the next two sentences of the article | nuclei typically contain 5% to 20% of the total galaxy light and are slightly resolved at the distance of virgo by _ hubble space telescope _
( _ hst _ ) imaging @xcite . |
7,220 | Suppose that you have an abstract for a scientific paper: beams that experience third - harmonic generation ( thg ) also experience kerr effects . with kerr effects
, beams do not take simple gaussian shapes , but exhibit nonlinear dynamics .
these nonlinear dynamics have an effect on the thg accumulated by focusing and then diverging beams .
we formulate a self - consistent and complete set of nonlinear schrdinger equations for a pair of coupled beams a fundamental and its third - harmonic .
numerical simulations show that the kerr nonlinearities allow some third - harmonic to propagate to the far - field even for zero or negative phase - mismatch .
this is because the nonlinear dynamics break the beams reflection symmetry about the focal plane and therefore increases far - field thg by changing some of the interference from destructive to constructive .
thg conversion efficiencies are computed as functions of several beam parameters . .
And you have already written the first three sentences of the full article: we study the dynamics of two - color beams in a nonlinear isotropic medium .
we take the initial conditions to be a one - color beam with gaussian profile . with a cubic ( @xmath0 ) nonlinearity , which is the lowest order possible in an isotropic medium , the possible nonlinearities are thg , kerr , and raman .
any other nonlinearity requires either a different susceptibility ( second - harmonics , high - harmonics ) , or more than two slowly - varying envelopes ( sum and difference frequency generation ) ..
Please generate the next two sentences of the article | this is one of the simplest nonlinear optics problems , and is for that reason important ; it has an application to third - harmonic generation ( thg ) microscopy @xcite .
the usual model of thg takes the fundamental beam to be gaussian , and ( inconsistently , or as an approximation ) has thg as the sole nonlinearity @xcite . |
7,221 | Suppose that you have an abstract for a scientific paper: the stability of metal - free very massive stars ( @xmath0 = 0 ; @xmath1 ) is analyzed and compared with metal - enriched stars .
such zero - metal stars are unstable to nuclear - powered radial pulsations on the main sequence , but the growth time scale for these instabilities is much longer than for their metal - rich counterparts .
since they stabilize quickly after evolving off the zams , the pulsation may not have sufficient time to drive appreciable mass loss in z = 0 stars . for reasonable assumptions regarding the efficiency of converting pulsational energy into mass loss
, we find that , even for the larger masses considered , the star may die without losing a large fraction of its mass .
we find a transition between the @xmath2- and @xmath3-mechanisms for pulsational instability at @xmath4 .
for the most metal - rich stars , the @xmath3-mechanism yields much shorter @xmath5-folding times , indicating the presence of a strong instability .
we thus stress the fundamental difference of the stability and late stages of evolution between very massive stars born in the early universe and those that might be born today . 0.1 in 0.1 in .
And you have already written the first three sentences of the full article: [ sec : intro ] the formation and nature of the first generation of so - called population iii ( pop iii ) stars have been studied and speculated about for over thirty years ( schwarzschild & spitzer 1953 ; yoneyama 1972 ; hartquist & cameron 1977 ; palla , salpeter & stahler 1983 ; silk 1983 ; and many others ) , but the extent to which they differed from present day stars in ways other than composition is still debated . recently , three - dimensional cosmological simulations have reached sufficient resolution on small scales to begin to address the star formation problem ( ostriker & gnedin 1996 ; abel et al . 1998 ) .
while considerable uncertainty remains regarding the continued evolution of the dense knots they find in their calculations , these simulations do not exclude the formation of a first generation of quite massive stars @xmath6 ( _ e.g. _ , larson 1999 ; abel , bryan , & norman 2000 ) . using different numerical methods to analyze the fragmentation of primordial clouds , bromm et al .
( 1999 ) reached similar conclusions . without further study , especially including the complexity of radiation transport and molecular opacities , it may be premature to conclude that _ all _ pop iii stars were so massive , but there certainly exists adequate motivation to examine the properties of such stars ..
Please generate the next two sentences of the article | in particular , if such massive pop iii stars were ever born , would they retain their large masses until death ?
that is , would they die as pair - instability supernovae , with possible unique signatures of nucleosynthesis and black hole formation , or would they lose most of their mass and die much the same as present day stars ? |
7,222 | Suppose that you have an abstract for a scientific paper: we consider the problem @xmath0 in @xmath1 , under the assumption @xmath2 , and with the non linear term @xmath3 with a _
double power _ behavior .
we prove the existence two solutions when @xmath4 is sufficiently small and @xmath5 .
* keywords : * nonlinear equations , variational methods , orlicz spaces .
And you have already written the first three sentences of the full article: we consider the existence of solutions of the following nonhomogeneous problem @xmath6 where the energy functional is defined by @xmath7 the nonlinearity is given by a function @xmath3 of _ double power _ type that is an even function @xmath8 with @xmath9 satisfying the following requirements : 1 .
there exist positive numbers @xmath10 with @xmath11 such that + @xmath12 + @xmath13 2 .
there exists @xmath14 and @xmath15 such that , for all @xmath16 @xmath17 3 . for any @xmath18 we have @xmath19 for example.
Please generate the next two sentences of the article | the required assumptions are satisfied by @xmath20 with @xmath21 small enough , as shown in the appendix .
we assume @xmath22 , for some @xmath23 and @xmath24 moreover , we want @xmath25 and @xmath5 on a set of positive measure . in @xcite the existence of two positive solutions @xmath26 of the equation @xmath27 is proved when @xmath28 satisfies @xmath29 , @xmath30 . |
7,223 | Suppose that you have an abstract for a scientific paper: we present a multiwavelength study of the black hole x - ray binary v404 cyg in quiescence , focusing upon the spectral energy distribution ( sed ) .
radio , optical , uv , and x - ray coverage is simultaneous .
we supplement the sed with additional non - simultaneous data in the optical through infrared where necessary .
the compiled sed is the most complete available for this , the x - ray and radio brightest quiescent black hole system .
we find no need for a substantial contribution from accretion light from the near - uv to the near - ir , and in particular the weak uv emission constrains published spectral models for v404 cyg .
we confirm that no plausible companion spectrum and interstellar extinction can fully explain the mid - ir , however , and an ir excess from a jet or cool disc appears to be required .
the x - ray spectrum is consistent with a @xmath0 power - law as found by all other studies to date .
there is no evidence for any variation in the hardness over a range of a factor of 10 in luminosity .
the radio flux is consistent with a flat spectrum ( in @xmath1 ) . the break frequency between a flat and optically thin spectrum
most likely occurs in the mid or far - ir , but is not strongly constrained by these data .
we find the radio to be substantially variable but with no clear correlation with x - ray variability .
[ firstpage ] accretion , accretion discs binaries : close stars : individual : v404 cyg .
And you have already written the first three sentences of the full article: the question of how accretion onto a black hole occurs has been of great and ongoing interest .
observations of accreting sources provide a test of astrophysics in the strong gravity regime and will potentially yield a signature of the presence of an event horizon around black holes .
recent advances in x - ray technology have revealed that accretion can occur at extremely low rates across the range of black hole masses from stellar remnants to supermassive black holes at the centre of our own and other galaxies ..
Please generate the next two sentences of the article | however , the nature of that low - level accretion remains unclear ( see e.g. , @xcite ) .
accretion flows at low luminosities do appear to be radiatively inefficient , but we have yet to determine to what extent that arises from advection of hot gas through the event horizon , and what role jets may play in carrying away energy @xcite . |
7,224 | Suppose that you have an abstract for a scientific paper: we present a census of the population of deeply embedded young stellar objects ( ysos ) in the perseus molecular cloud complex based on a combination of spitzer space telescope mid - infrared data from the `` cores to disks '' ( c2d ) legacy team and jcmt / scuba submillimeter maps from the complete team .
the mid - infrared sources detected at 24 @xmath0 m and having @xmath1-[4.5]>1 $ ] are located close to the center of the scuba cores , typically within 15 of their peaks .
the narrowness of the spatial distribution of mid - infrared sources around the peaks of the scuba cores suggests that no significant dispersal of the newly formed ysos has occurred .
this argues against the suggestion that motions of protostars regulate the time scales over which significant ( bondi - hoyle ) accretion can occur .
the ysos are found to have red @xmath1-[4.5]$ ] and @xmath2-[24]$ ] colors , but not comparable red @xmath3-[8.0]$ ] colors .
the most deeply embedded ysos are found in regions with high extinction , @xmath4 , similar to the extinction threshold observed for the scuba cores .
all the scuba cores with high concentrations have embedded ysos , but not all cores with low concentrations are starless . from the above considerations a relatively unbiased sample of 49 deeply embedded ysos
is constructed .
embedded ysos are found in 40 of the 72 scuba cores with only three cores harboring multiple embedded ysos within 15@xmath5 .
the equal number of scuba cores with and without embedded ysos suggests that the time scale for the evolution through the dense prestellar stages , where the cores are recognized in the submillimeter maps and have central densities of @xmath6 @xmath7 , is similar to the time scale for the embedded protostellar stages .
the current star formation efficiency of cores is estimated to be approximately 1015% .
in contrast , the star formation efficiency averaged over the cloud life time and compared to the total cloud mass is only a few percent , reflecting also the....
And you have already written the first three sentences of the full article: any theory of low - mass star formation should not only be able to make predictions for one characteristic stage such as the core mass spectrum in molecular clouds or the initial mass function of emerging stars - but also relate those through both pre- and protostellar stages . a number of the very basic questions of star formation still remain unanswered and debated ( see , e.g. , @xcite , @xcite and @xcite for recent reviews and discussions of both observational and theoretical studies ) , which can be addressed with large homogeneous surveys from mid - infrared through ( sub)millimeter wavelengths and well - defined lists of sources such as those presented in this paper . for example , is the star formation process highly dynamical with cores being transient phenomena in a turbulent medium and are protostars only accreting in short periods of time when `` passing by '' these dense environments ( i.e. , bondi - hoyle accretion ) ? or is low - mass star formation a more slowly evolving process as preferred in traditional ambipolar diffusion scenarios and in that case , how important are other effects such as turbulence in regulating the speed by which the process occurs ? how efficient is the star formation process in turning prestellar dust and gas into young stars ?
are there specific relationships between the natal prestellar cores and the emerging protostars , for example : do the properties of prestellar cores reflect in whether a given core actually forms a star and perhaps whether it forms a single or multiple system ? many of these discussions hinge on statistical arguments , for example estimates of the evolutionary rate of protostars through counts of the number of ysos in different stages . previous studies of the deeply embedded stages were hampered by low sensitivity single element ( sub)millimeter receivers and confusion in low resolution , low sensitivity infrared observations such as those from the iras and iso satellites . in the last few years systematic , detailed surveys of larger regions....
Please generate the next two sentences of the article | the earliest , most deeply embedded stages of low - mass protostars or the latest stages of prestellar cores close to the onset of collapse are important for insight into the physical conditions regulating low - mass star formation . approaching the problem from the prestellar stages ,
continuum observations provide strong constraints on the distribution of dust , and through inference the gas , in star forming regions . |
7,225 | Suppose that you have an abstract for a scientific paper: we present the first numerical observation of lyapunov modes ( mode structure of lyapunov vectors ) in a system maintained in a nonequilibrium steady state .
the modes show some similarities and some differences when compared with the results for equilibrium systems .
the breaking of energy conservation removes a zero exponent and introduces a new mode .
the transverse modes are only weakly altered but there are systematic changes to the longitudinal and momentum dependent modes . .
And you have already written the first three sentences of the full article: the difference of two trajectories starting from infinitesimally nearby initial conditions , which is called the lyapunov vector , plays an essential role in the description of stability or instability in dynamical systems .
the exponential rate of expansion or contraction of the absolute value of the lyapunov vector is the lyapunov exponent , and its positivity means that the system has a dynamical instability and is called chaotic .
the lyapunov vector is introduced in each independent direction of phase space , so in general we have to consider a set of lyapunov exponents , called the lyapunov spectrum , and the corresponding lyapunov vectors in a high - dimensional chaotic system ..
Please generate the next two sentences of the article | an algorithm to calculate the lyapunov exponents and vectors in many - body systems has been developed by benettin et al .
@xcite , and shimada and nagashima @xcite , and the behavior of lyapunov vectors has been investigated from various points of view , for example , the conjugate pairing rule for lyapunov spectra in some thermodynamic systems @xcite , and the localization behavior of lyapunov vectors @xcite , etc . |
7,226 | Suppose that you have an abstract for a scientific paper: we examine the disc jet connection in stellar mass and supermassive black holes by investigating the properties of their compact emission in the hard x - ray and radio bands .
we compile a sample of @xmath0100 active galactic nuclei with measured mass , 5 ghz core emission , and 2 - 10 kev luminosity , together with 8 galactic black holes with a total of @xmath0 50 simultaneous observations in the radio and x - ray bands . using this sample , we study the correlations between the radio ( @xmath1 ) and the x - ray ( @xmath2 ) luminosity and the black hole mass ( @xmath3 ) .
we find that the radio luminosity is correlated with _ both _ @xmath3 and @xmath2 , at a highly significant level .
we show how this result can be used to extend the standard unification by orientation scheme to encompass unification by mass and accretion rate . .
And you have already written the first three sentences of the full article: some galaxies are known to emit radiation with extremely high luminosities in the @xmath4-ray , x - ray , uv and radio continuum from a very concentrated volume in the nuclear region .
such active cores are the so - called active galactic nuclei ( agn ) and their radiation is believed to be produced by accretion onto a supermassive black hole . the intrinsically complex nature of such systems and the differences in the terminology among different scientific communities ( radio , optical , x - ray astronomers ) has led to an extremely complicated nomenclature for the agn zoo . as the wealth of observations piled up , and with them the number of different agn types , the opposite enterprise of finding unification schemes has progressively gained support . the basic idea behind
the standard unification scheme is that agn are asymmetric and anisotropic systems ..
Please generate the next two sentences of the article | this is natural , as all rotating systems necessarily single out a preferential axis in space and break the full spherical symmetry of non - rotating bodies .
therefore , the orientation of the agn rotation axis with respect to our line of sight becomes another important parameter that can cause apparent observational differences in two sources that are intrinsically identical ( _ unification by orientation _ ) . according to the current |
7,227 | Suppose that you have an abstract for a scientific paper: we consider a brownian particle moving on a ring .
we study the probability distributions of the total number of turns and the net number of counter - clockwise turns the particle makes till time @xmath0 . using a method based on the renewal properties of brownian walker
, we find exact analytical expressions of these distributions .
this method serves as an alternative to the standard path integral techniques which are not always easily adaptable for certain observables . for large @xmath0
, we show that these distributions have gaussian scaling forms .
we also compute large deviation functions associated to these distributions characterizing atypically large fluctuations .
we provide numerical simulations in support of our analytical results . .
And you have already written the first three sentences of the full article: starting from the pioneering works of edwards @xcite , statistical studies of winding properties of topologically constrained random processes have been a subject of keen interest in various contexts such as in the physics of polymers @xcite , the fluxlines in superconductors @xcite and many others .
the winding properties of planar brownian paths have also been a subject of interest to mathematicians for a long time . in 1958 , spitzer @xcite studied the distribution of the total angle @xmath1 wound by a planar brownian path around a prescribed point in time @xmath0 .
he showed that in the large time limit the scaled random variable @xmath2 has a cauchy distribution _.
Please generate the next two sentences of the article | i.e. _ with infinite first moment . later
, various generalizations and extensions of this classic result have been put forward @xcite . |
7,228 | Suppose that you have an abstract for a scientific paper: we report on @xmath0 photometry and spectroscopy for mk classification purposes carried out in the fields of five open clusters projected against the vela gum in the third galactic quadrant of the galaxy .
they are ruprecht 20 , ruprecht 47 , ruprecht 60 , ngc 2660 and ngc 2910 .
we could improve / confirm the parameters of these objects derived before .
ruprecht 20 is not a real physical entity , in agreement with earlier suggestions .
ruprecht 47 , a young cluster in the galactic plane , at 4.4 kpc from the sun is quite farther than in previous distance estimations and becomes , therefore , a member of the puppis ob2 association .
for the first time ruprecht 60 was surveyed in @xmath0 photometry .
we found it to be placed at 4.2 kpc from the sun of about and 1 gyr old .
ngc 2660 is another old object in our survey for which distance and age are coincident with previous findings .
ngc 2910 turns out to be a young cluster of vela ob1 association at a distance of 1.4 kpc approximately and 60 myr old .
the spectroscopic parallax method has been applied to several stars located in the fields of four out of the five clusters to get their distances and reddenings . with this method we found two blue stars in the field of ngc 2910 at distances that make them likely members of vela ob1 too .
also , projected against the fields of ruprecht 20 and ruprecht 47 we have detected other young stars favoring not only the existence of puppis ob1 and ob2 but conforming a young stellar group at @xmath1 kpc from the sun and extending for more than 6 kpc outward the galaxy . if this is the case , there is a thickening of the thin galactic disk of more than 300 pc at just 2 - 3 kpc from the sun .
ruprecht 60 and ngc 2660 are too old objects that have no physical relation with the associations under discussion .
an astonishing result has been the detection in the background of ruprecht 47 of a young star at the impressive distance of 9.5 kpc from the sun that could be a member of the innermost part of the....
And you have already written the first three sentences of the full article: this investigation forms part of a long term project aimed at understanding the nearby spiral structure in the third galactic quadrant of the milky way ( hereinafter tgq ) from an optical point of view by means of open clusters .
the still unresolved question about the grand design structure of the milky way ( see , e.g. choi et al .
2014 ) has been demanding an extraordinary observational effort during the last decades . actually , a crucial starting point took place in the @xmath2 when georgelin & georgelin ( 1976 ) produced the first map of the galaxy utilizing hii regions as spiral tracers ..
Please generate the next two sentences of the article | this first map showed that a four arms model fits the observations very well , a concept widely used yet .
since then , a number of other maps showing the structure of the galaxy have been developed by means of different spiral tracers such as molecular clouds ( efremov 1998 ) or by combining them with hii regions ( hou et al . |
7,229 | Suppose that you have an abstract for a scientific paper: we examine in detail the changes in the production of primordial helium resulting from nonthermal neutrino momentum distributions produced by resonant transformation of electron - type neutrinos to steriles .
these transformations , @xmath0 ( @xmath1 ) , amplify a positive ( negative ) lepton number asymmetry .
we find that the resulting supression relative to a thermal distribution of low energy @xmath2 reduces @xmath3 conversion to a greater extent than does the enhancement of @xmath3 from an identical suppression of @xmath4 .
thus , equal lepton - number asymmetries of opposite sign have unequal effects on the resulting helium yield in primordial nucleosynthesis .
amssym.tex # 1#23.6pt , _ et al . , _ .
And you have already written the first three sentences of the full article: the role of neutrinos in primordial nucleosynthesis has been exploited to infer constraints on the number of leptons and light neutrinos in the standard model of particle physics @xcite .
complimentary to this , the width of the @xmath5 was found to allow only three light weakly - coupled neutrinos @xcite .
this experimental determination of the number of neutrinos , @xmath6 , has led some to describe primordial nucleosynthesis as determined by only one parameter : the baryon - to - photon ratio , @xmath7 . along with the assumptions of homogeneity and isotropy ,.
Please generate the next two sentences of the article | the theory of standard big bang nucleosynthesis ( sbbn ) predicts the abundance of the lightest nuclides within reasonable error through the single parameter @xmath7 .
now , however , indications of neutrino oscillations from the atmospheric muon neutrino deficit , the solar neutrino deficit and the lsnd excess may prove that our understanding of neutrino physics is incomplete @xcite . this uncertainty in neutrino |
7,230 | Suppose that you have an abstract for a scientific paper: in this paper we study second order non - linear periodic systems driven by the ordinary vector @xmath0-laplacian with a non - smooth , locally lipschitz potential function .
our approach is variational and it is based on the non - smooth critical point theory .
we prove existence and multiplicity results under general growth conditions on the potential function .
then we establish the existence of non - trivial homoclinic ( to zero ) solutions .
our theorem appears to be the first such result ( even for smooth problems ) for systems monitored by the @xmath0-laplacian . in the last section of the paper
we examine the scalar and semilinear problem .
our approach uses a generalized landesman
lazer type condition which generalizes previous ones used in the literature .
also for the semilinear case the problem is at resonance at any eigenvalue .
= mtsyb at 10pt .
And you have already written the first three sentences of the full article: in a recent paper [ 28 ] , we proved existence and multiplicity results for non - linear second - order periodic systems driven by the one - dimensional @xmath0-laplacian and having a non - smooth potential .
our results there extended to the recent works of tang [ 31,32 ] , who examined semilinear ( i.e. @xmath1 ) systems with smooth potential . in this paper
we continue the study of non - linear , non - smooth periodic systems ..
Please generate the next two sentences of the article | we prove new existence theorems under more general growth conditions on the non - smooth potential . in [ 28 ]
all the results assumed a strict sub-@xmath0 growth ( i.e. strictly sublinear potential in the semilinear ( @xmath1 ) case ) . here |
7,231 | Suppose that you have an abstract for a scientific paper: we consider a measurement of exclusive production of scalar @xmath0 meson in the proton - proton collisions at lhc and rhic and in the proton - antiproton collisions at the tevatron via @xmath1 decay .
the corresponding amplitude for exclusive double - diffractive @xmath2 meson production was obtained within the @xmath3-factorization approach including virtualities of active gluons and the corresponding cross section is calculated with unintegrated gluon distribution functions ( ugdfs ) known from the literature .
the four - body @xmath4 reaction constitutes an irreducible background to the exclusive @xmath2 meson production .
we calculate several differential distributions for @xmath5 process including absorptive corrections . the influence of kinematical cuts on the signal - to - background ratio is investigated .
corresponding experimental consequences are discussed . .
And you have already written the first three sentences of the full article: the mechanism of exclusive production of mesons at high energies became recently a very active field of research ( see e.g. ref .
@xcite and references therein ) .
central exclusive production processes represent a very promising and novel way to study qcd in hadron - hadron collisions ..
Please generate the next two sentences of the article | recently , there is a growing interest in understanding exclusive three - body reactions @xmath6 at high energies , where the meson ( resonance ) @xmath7 is produced in the central rapidity region . in particular , these reactions provide a valuable tool to investigate in detail the properties of resonance states .
many of the resonances decay into @xmath8 and/or @xmath9 channels . |
7,232 | Suppose that you have an abstract for a scientific paper: we inject current pulses into uniformly magnetized patterns of thin films of the itinerant ferromagnet srruo@xmath0 , while monitoring the effective temperature of the patterns during the current injection .
we gradually increase the amplitude of the pulses until magnetization reversal occurs .
we observe magnetization reversal induced by current above a temperature dependent threshold and show that this effect is not simply due to sample heating or oersted fields .
we discuss the applicability of current - induced spin - wave instability scenario . .
And you have already written the first three sentences of the full article: the shrinking size of spintronics devices and the need for efficient and scalable methods for their manipulation has led to enhanced interest in spin - torque effects of electrical current on the magnetic configuration of nanostructures .
the study in this direction has focused so far on effects related to magnetic nonuniformity ; in particular , the effect of current on ferromagnetic domain walls which yields domain wall motion @xcite and the effect of current on magnetic heterostructures which yields magnetic switching @xcite .
both effects have been observed in different systems and they appear to be useful for novel memory devices ..
Please generate the next two sentences of the article | a more subtle effect of magnetic nonuniformity is expected when a single uniformly magnetized nanostructure is connected via asymmetric contacts to normal metals . in this case ,
asymmetric spin accumulation near the two contacts may induce magnetic instability @xcite . based on several theoretical works , |
7,233 | Suppose that you have an abstract for a scientific paper: we investigate superradiant cascade emissions from an atomic ensemble driven by two - color classical fields .
the correlated pair of photons ( signal and idler ) is generated by adiabatically driving the system with large - detuned light fields via four - wave mixing .
the signal photon from the upper transition of the diamond - type atomic levels is followed by the idler one which can be superradiant due to light - induced dipole - dipole interactions .
we then calculate the cooperative lamb shift ( cls ) of the idler photon , which is a cumulative effect of interaction energy .
we study its dependence on a cylindrical geometry , a conventional setup in cold atom experiments , and estimate the maximum cls which can be significant and observable .
manipulating the cls of cascade emissions enables frequency qubits that provide alternative robust elements in quantum network .
superradiance ; cold atoms ; cascade atomic transitions ; two - photon spontaneous emissions ; quantum telecommunication .
And you have already written the first three sentences of the full article: superradiance @xcite is a coherent and collective radiation from a multi - atom system .
the radiation intensity is proportional to the square of particle number along with a shorter time variation , which conserves radiation energy .
this collective radiation originates from a common light - matter interaction , through which spontaneously emitted photons can be reabsorbed by the atoms @xcite if they are close to each other , and interatomic phase correlations build up @xcite ..
Please generate the next two sentences of the article | this spontaneous emission decays in an enhanced rate proportional to the number of particles , which is very different from spontaneous emissions of independent and uncorrelated single atoms @xcite .
many theoretical works from different perspectives have investigated the superradiant emission . |
7,234 | Suppose that you have an abstract for a scientific paper: process algebra has been successful in many ways ; but we do nt yet see the lineaments of a fundamental theory . some fleeting glimpses are sought from petri nets , physics and geometry .
concurrency , process algebra , petri nets , geometry , quantum information and computation . .
And you have already written the first three sentences of the full article: what counts as a successful theory in computer science ? consider obvious exemplars such as * process calculi * type systems * model - checking it is not the case that there is a single agreed model , notation , formalism , tool or language in any of the above areas .
in fact there are a profusion of all of these , although some have been particularly influential .
( insert your favourite examples here ) [ [ the - next-700-cdots - syndrome ] ] the ` next 700 @xmath0 ' syndrome + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + is this profusion a ` scandal ' of our subject ?.
Please generate the next two sentences of the article | i used to think so and i was nt alone ( e.g. robin milner s quest to find the ` @xmath1-calculus of concurrency ' ) .
now i am not so sure . [ [ its - the - paradigms ] ] it s the _ paradigms ! _ |
7,235 | Suppose that you have an abstract for a scientific paper: searching for transit timing variations in the known transiting exoplanet systems can reveal the presence of other bodies in the system . here
we report such searches for two transiting exoplanet systems , tres-1 and wasp-2 .
their new transits were observed with the 4.2 m william herschel telescope located on la palma , spain . in a continuing programme ,
three consecutive transits were observed for tres-1 , and one for wasp-2 during september 2007 .
we used the markov chain monte carlo simulations to derive transit times and their uncertainties .
the resulting transit times are consistent with the most recent ephemerides and no conclusive proof of additional bodies in either system was found . .
And you have already written the first three sentences of the full article: transiting planets provide a wealth of information about exoplanetary systems .
short - term variations in the mid - eclipse times of the transits may reveal the presence of moons , trojans or other planets ( ( * ? ? ?
* holman & murray 2005 ) , ( * ? ? ?.
Please generate the next two sentences of the article | * agol 2005 ) , ( * ? ? ?
* ford & holman 2007 ) ) , whereas long - term variations could result from orbital precession ( ( * ? ? ? |
7,236 | Suppose that you have an abstract for a scientific paper: we study a continuous time markov process whose state space consists of an assignment of @xmath0 or @xmath1 to each vertex of a graph @xmath2 .
the graphs that we treat are related to homogeneous trees of degree @xmath3 , such as finite or infinite stacks of such trees .
the initial spin configuration is chosen from a bernoulli product measure with density @xmath4 of @xmath0 spins .
the system evolves according to an agreement inducing dynamics : each vertex , at rate 1 , changes its spin value to agree with the majority of its neighbors .
we study the long time behavior of this system and prove that , if @xmath4 is close enough to 1 , the system reaches fixation to consensus .
the geometric percolation - type arguments introduced here may be of independent interest . .
And you have already written the first three sentences of the full article: in this work we study the long term behavior of continuous time markov processes whose states assign either @xmath0 or @xmath1 ( usually called a spin value ) to each vertex @xmath5 in a graph @xmath2 .
the graphs @xmath2 we consider are related to homogeneous trees of degree @xmath6 and include infinite stacks of homogeneous trees .
these graphs will be specified in section [ sec : themodel ] , where we will also discuss some earlier papers where such stacks of trees have been studied ..
Please generate the next two sentences of the article | the geometric and percolation theoretic methods we introduce to carry out our analysis ( see especially section [ sec : main ] and appendix [ app : geometric ] ) are potentially of independent interest .
we denote by @xmath7 the value of the spin at vertex @xmath8 at time @xmath9 . |
7,237 | Suppose that you have an abstract for a scientific paper: the ratio of the @xmath0 ( @xmath1 ) and @xmath2 ( @xmath3 ) decay widths , @xmath4 , has been measured with stopped positive kaons . @xmath1 and @xmath3 samples containing 2.4@xmath5 and 4.0@xmath5 events , respectively ,
were analyzed .
the @xmath6 ratio was obtained to be [email protected](stat.)@xmath70.008(syst . ) calculating the detector acceptance by a monte carlo simulation .
the coefficient of the @xmath8 dependent term of the @xmath9 form factor was also determined to be @[email protected](stat.)@xmath70.004(syst . ) with the assumption of @xmath11-@xmath12 universality in @xmath13 decay .
the agreement of our result with the @xmath10 value obtained from @xmath14 dalitz plot analyses supports the validity of the @xmath11-@xmath12 universality . , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , and .
And you have already written the first three sentences of the full article: the spectroscopic studies to determine form factors of the @xmath15 semi - leptonic decays , @xmath16 ( @xmath17 ) , are of importance both in studying low energy properties of the strong interaction in terms of effective theories @xcite , and also in studying fundamental interactions . in our previous work @xcite , we reported a result testing the exotic couplings in @xmath2 ( @xmath3 ) decay , showing the non existence of scalar and tensor interactions , contradicting the current world average adopted by particle data group @xcite . in the present work , the @xmath0 ( @xmath1 ) events , which were collected simultaneously , were analyzed to determine the ratio of the @xmath1 and @xmath3 decay widths @xmath6 .
this quantity is one of the most important observables to evaluate the @xmath13 form factors .
assuming that only the v@xmath18a interaction contributes to the @xmath19 decay , the decay amplitude can be described by two dimensionless form factors , @xmath20 and @xmath21 , which are functions of the momentum transfered to the leptons @xmath22=@xmath23 where @xmath24 and @xmath25 are the four momenta of the @xmath26 and @xmath27 , respectively ..
Please generate the next two sentences of the article | they are given as , @xmath28 , \nonumber \\ f_{0}(q^{2})&=&f_{0}(0)[1+\lambda_{0}(q / m_{\pi})^{2 } ] .
\nonumber\end{aligned}\ ] ] assuming @xmath11-@xmath12 universality , the form factors between @xmath29 and @xmath30 decays are identical and @xmath6 can be written as @xcite , @xmath31 this equation can not determine the @xmath32 and @xmath10 parameters uniquely but simply fixes a relationship between them . |
7,238 | Suppose that you have an abstract for a scientific paper: in view of the current interest in combining different observations to constraint annihilating wimp dark matter , we examine the relation between the sommerfeld effect at the recombination epoch and in the galactic halo . by considering an up - to - date collection of interpolations of cosmic rays lepton data ( ams-02 2014 , fermi and pamela ) , as dark matter annihilation signals ,
we show that current cosmic rays measurements and recent planck 2015 constraints from cmb anisotropies almost overlap for dark matter masses of the order of few @xmath0 , although great theoretical uncertainties afflict cosmic rays and dark matter descriptions . combining cosmic rays
fits we obtain proper minimal regions allowed by cmb observations , especially for @xmath1 and @xmath2 annihilation channels , once assumed viable values of the efficiency factor for energy absorption at recombination : the results are consistent with those obtained by the planck collaboration but allow a slightly larger overlap between cosmic rays constraints from the lepton sector and cmb .
incoming ams-02 measurements of cosmic rays antiprotons will help to clarify the conundrum .
dark matter , ams-02 , planck .
And you have already written the first three sentences of the full article: ams-02 2014 measurements of cosmic rays ( cr ) leptons @xcite , which have confirmed the rise of the positron fraction for kinetic energy above @xmath3 , up to @xmath4 , have stimulated different interpretations of this excess of positrons as primary evidence of dark matter ( dm ) annihilation .
the interpretation of dm as a new source of positrons , to explain the departure from the pure secondary positron fraction , can be tested with other complementary and independent indirect measurements , as the cosmic microwave background ( cmb ) anisotropies .
in fact , if dm particles self - annihilate at a sufficient rate , the expected signal would be directly sensitive to their thermally averaged cross section and it could have drawn an imprint on cmb temperature and polarization anisotropies ..
Please generate the next two sentences of the article | the aim of the present letter is to discuss the link between the dm annihilation cross sections at freeze - out , recombination and in the milky way galactic halo , which is essential to compare different indirect constraints on dm itself .
the three different physical quantities are defined by the environment in three different epochs . |
7,239 | Suppose that you have an abstract for a scientific paper: this paper investigates the lift force exerted on an elliptical obstacle immersed in a granular flow through analytical calculations and computer simulations .
the results are shown as a function of the obstacle size , orientation with respect to the flow direction ( tilt angle ) , the restitution coefficient and ellipse eccentricity .
the theoretical argument , based on the force exerted on the obstacle due to inelastic , frictionless collisions of a very dilute flow , captures the qualitative features of the lift , but fails to reproduce the data quantitatively .
the reason behind this disagreement is that the dilute flow assumption on which this argument is built breaks down as a granular shock wave forms in front of the obstacle .
more specifically , the shock wave change the grains impact velocity at the obstacle , decreasing the overall net lift obtained from a very dilute flow . .
And you have already written the first three sentences of the full article: granular matter is a generic name given to a system composed of macroscopic , athermal particles that have mutual repulsive , dissipative interactions @xcite .
it is an intensely studied field in the physics community given the several distinct behaviors shown by such systems as a consequence of different external conditions imposed on them .
one of such conditions is that which imposes a flow of particles , named granular flow @xcite . within the several granular flow examples ,.
Please generate the next two sentences of the article | the flow around immersed obstacles has received some attention lately @xcite .
one of the objectives of such investigations is to measure the force in the obstacle due to interactions with the flowing grains , the so called granular drag @xcite , analogously to the viscous flow force on an obstacle . on the other hand |
7,240 | Suppose that you have an abstract for a scientific paper: we present a progress report on an ongoing h@xmath0 imaging survey of nearby clusters of galaxies .
four clusters have been surveyed to date : a1367 , a1656 , a347 and a569 .
a preliminary comparison of h@xmath0 luminosity functions obtained from our imaging survey with those from the prism survey reveals a significant level of incompleteness in the latter .
this in turn is due to a combination of insensitivity to low - luminosity emission - line galaxies and to brighter galaxies with weak extended h@xmath0 emission .
the survey has also revealed a unique population of clustered dwarf emission - line objects which may be the results of recent tidal encounters between larger gas - rich galaxies .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: with the mosaic ccd imager on the 0.92 m telescope at kpno , we are able to cover an 1@xmath1 field in a single observation , and reach limiting fluxes corresponding to star formation rates ( sfrs ) of about 0.1 m@xmath2/yr for extended galaxies and @xmath30.01 m@xmath2/yr for compact emission - line galaxies
. the broad goals of the survey are to construct a complete inventory of star forming galaxies in a well - defined volume limited sample , to characterize the demographics of the local star forming population , and to quantify the completeness of other methods for measuring the local sfr density .
we are also carrying out a parallel survey of a local field sample , so we also will be able to study the influences of cluster environment on the sfrs ..
Please generate the next two sentences of the article | we have observed four clusters so far during an observing run in february 1999 .
these clusters have been observed previously by moss , whittle , & pesce ( 1998 : mwp98 ) using an objective prism technique . in figure 1 , we show a flux distribution of h@xmath0-emitting galaxies in a1367 . also shown by shaded histograms are the distributions of the galaxies detected by mwp98 . although the analysis is still in the preliminary stage , the comparison between our data and those from mwp98 s prism survey suggests that @xmath4% of h@xmath0 flux is missing from the latter . |
7,241 | Suppose that you have an abstract for a scientific paper: the adsorption of a single ideal polymer chain on energetically heterogeneous and rough surfaces is investigated using a variational procedure introduced by garel and orland ( _ phys .
rev .
b _ * 55 * ( 1997 ) , 226 ) . the mean polymer size is calculated perpendicular and parallel to the surface and is compared to the gaussian conformation and to the results for polymers at flat and energetically homogeneous surfaces .
the disorder - induced enhancement of adsorption is confirmed and is shown to be much more significant for a heterogeneous interaction strength than for spatial roughness .
this difference also applies to the localization transition , where the polymer size becomes independent of the chain length .
the localization criterion can be quantified , depending on an effective interaction strength and the length of the polymer chain . .
And you have already written the first three sentences of the full article: the adsorption of polymers on flat and homogeneous attractive surfaces has been the subject of many investigations , see e.g. @xcite , but naturally occurring surfaces usually are rough and/or energetically inhomogeneous , the heterogeneity leading to an enhancement of adsorption under quite general conditions @xcite : already simple physical arguments contain the statement that upon increasing the surface irregularity , the number of polymer - surface interactions is strongly enhanced relative to the idealized planar surface ( see figure [ fig : flory1 ] ) .
this is a consequence of a larger probability of polymer - surface intersection with increasing roughness .
the study presented here is partly motivated by the theoretical investigation of reinforcement mechanisms in carbon black filled elastomers , where the polymer adsorption is substantial as there is a strong binding of the polymers to the surface ( leading to a layer of localized polymers , the so called `` bound rubber '' @xcite ) ..
Please generate the next two sentences of the article | these surfaces are rough and even fractal on many decades of their size , down to the molecular size range , as well as highly energetically ( i.e. chemically ) heterogeneous : the distribution of interaction strengths can be characterized by high energy sites surrounding a relatively low energy background . therefore in principle both kinds of disorder should be incorporated in a theory which is supposed to explain the bound rubber phenomenon . in the literature
so far spatial and energetical heterogeneities were always treated separately . in this paper |
7,242 | Suppose that you have an abstract for a scientific paper: deformed states in @xmath0ca are investigated with a method of antisymmetrized molecular dynamics . above the spherical ground state ,
rotational bands arise from a normal deformation and a superdeformation as well as an oblate deformation .
the calculated energy spectra and @xmath1 transition strengths in the superdeformed band reasonably agree to the experimental data of the superdeformed band starting from the @xmath2 state at 5.213 mev . by the analysis of single - particle orbits
, it is found that the superdeformed state has particle - hole nature of an @xmath3-@xmath4 configuration .
one of new findings is parity asymmetric structure with @xmath5c+@xmath6si - like clustering in the superdeformed band .
we predict that @xmath5c+@xmath6si molecular bands may be built above the superdeformed band due to the excitation of inter - cluster motion .
they are considered to be higher nodal states of the superdeformed state .
we also suggest negative - parity bands caused by the parity asymmetric deformation . .
And you have already written the first three sentences of the full article: in the spectra of @xmath0ca , the existence of low - lying deformed states has long been known since 1960s@xcite .
the coexistence of the spherical and various deformed states in the doubly magic nuclei @xmath0ca has attracted a great interest . in the positive parity states below 7 mev , besides the spherical ground state , the existence of two deformed rotational bands built on the @xmath7 state at 3.35 mev and the @xmath2 state at 5.21 mev is known experimentally .
the structure of these bands has been often discussed in relation to many - particle many - hole states of nuclei in this mass region for a long time ..
Please generate the next two sentences of the article | grace and green @xcite firstly suggested that the former band is dominantly a @xmath8-@xmath9 state , while the latter band with a large deformation is understood as an @xmath3-@xmath4 state .
the member states of the first @xmath10=@xmath11 rotational band built on the @xmath7 state are known to be strongly populated by @xmath12-transfer reactions and to have the large @xmath12 spectroscopic factors @xcite . |
7,243 | Suppose that you have an abstract for a scientific paper: we propose a technique to test the idea that non - standard dynamics , rather than dark matter halos , might be responsible for the observed rotation curves of spiral galaxies . in the absence of non - luminous matter
, a galactic disk s rotational velocity and its vertical velocity dispersion can be used jointly to test the self - consistency of the galaxy s dynamics .
a specific illustrative example , using recent measurements of the disk kinematics of m33 , shows this to be a promising approach to assess the viability of modified newtonian dynamics ( mond ) . .
And you have already written the first three sentences of the full article: understanding the structure and kinematics of spiral galaxies , in particular explaining their rotation curves at large galactic radii , remains one of the pressing open questions in astrophysics .
optical observations of galactic rotation curves find that rather than falling off as one would expect from galaxy models where the mass traces the observed light , the rotational velocities remain constant at large radii .
these findings are further borne out by radio observations of the 21 cm line , from hi gas in the outer parts of the galactic disk ..
Please generate the next two sentences of the article | an overview of rotation curves is provided in @xcite , @xcite and @xcite .
there is strong evidence from the cmb data for considerable amounts of non - baryonic dark matter on the cosmological scale @xcite . |
7,244 | Suppose that you have an abstract for a scientific paper: galaxy mergers are likely to play a role in triggering active galactic nuclei ( agn ) , but the conditions under which this process occurs are poorly understood . in paper
i , we constructed a sample of spatially offset x - ray agn that represent galaxy mergers hosting a single agn . in this paper , we use our offset agn sample to constrain the parameters that affect agn observability in galaxy mergers .
we also construct dual agn samples with similar selection properties for comparison .
we find that the offset agn fraction shows no evidence for a dependence on agn luminosity , while the dual agn fractions show stronger evidence for a positive dependence , suggesting that the merger events forming dual agn are more efficient at instigating accretion onto supermassive black holes than those forming offset agn .
we also find that the offset and dual agn fractions both have a negative dependence on nuclear separation and are similar in value at small physical scales .
this dependence may become stronger when restricted to high agn luminosities , though a larger sample is needed for confirmation .
these results indicate that the probability of agn triggering increases at later merger stages .
this study is the first to systematically probe down to nuclear separations of @xmath0 kpc ( @xmath1 kpc ) and is consistent with predictions from simulations that agn observability peaks in this regime .
we also find that the offset agn are not preferentially obscured compared to the parent agn sample , suggesting that our selection may be targeting galaxy mergers with relatively dust - free nuclear regions . .
And you have already written the first three sentences of the full article: accretion onto supermassive black holes ( smbhs ) , and the corresponding release of gravitational potential energy , power active galactic nuclei ( agn ) .
this process requires that a significant amount of matter in the interstellar medium of a galaxy experience a loss of angular momentum sufficient to ultimately be captured by the smbh s accretion disk .
numerical simulations suggest that major mergers of galaxies are an effective mechanism for removing angular momentum @xcite ..
Please generate the next two sentences of the article | observational evidence for this scenario includes bright quasi - stellar objects ( qsos ) that often show evidence of interactions or mergers at both obscured phases , such as dust - reddened qsos @xcite and ultra - luminous infrared galaxies ( ulirgs ; * ? ? ?
* ; * ? ? ? |
7,245 | Suppose that you have an abstract for a scientific paper: there has been a tremendous rise in the growth of online social networks all over the world in recent years .
this has facilitated users to generate a large amount of real - time content at an incessant rate , all competing with each other to attract enough attention and become trends .
while western online social networks such as twitter have been well studied , characteristics of the popular chinese microblogging network sina weibo have not been . in this paper , we analyze in detail the temporal aspect of trends and trend - setters in sina weibo , constrasting it with earlier observations on twitter .
first , we look at the formation , persistence and decay of trends and examine the key topics that trend in sina weibo . one of our key findings is that retweets are much more common in sina weibo and contribute a lot to creating trends . when we look closer , we observe that a large percentage of trends in sina weibo are due to the continuous retweets of a small amount of fraudulent accounts .
these fake accounts are set up to artificially inflate certain posts causing them to shoot up into sina weibo s trending list , which are in turn displayed as the most popular topics to users . .
And you have already written the first three sentences of the full article: in the past few years , social media services as well as the users who subscribe to them , have grown at a phenomenal rate .
this immense growth has been witnessed all over the world with millions of people of different backgrounds using these services on a daily basis to communicate , create and share content on an enormous scale . this widespread generation and consumption of content
has created an extremely complex and competitive online environment where different types of content compete with each other for the attention of users ..
Please generate the next two sentences of the article | thus it is very interesting to study how certain types of content such as a viral video , a news article , or an illustrative picture , manage to attract more attention than others , thus bubbling to the top in terms of popularity . through their visibility ,
these popular items and topics contribute to the collective awareness reflecting what is considered important . |
7,246 | Suppose that you have an abstract for a scientific paper: we study the variations of electron - phonon coupling and their spectroscopic consequences in response to sliding of two layers in bilayer graphene using first - principles calculations and a model hamiltonian .
our study shows that the long wave - length optical phonon modes change in a sensitive and unusual way depending on the symmetry as well as the parity of sliding atomic structures and that , accordingly , raman- and infrared - active optical phonon modes behave differently upon the direction and size of the sliding .
the renormalization of phonon modes by the interlayer electronic coupling is shown to be crucial to explain their anomalous behavior upon the sliding . also , we show that the crystal symmetry change due to the sliding affects the polarized stokes raman - scattering intensity , which can be utilized to detect tiny misalignment of graphene layers using spectroscopic tools
. successful isolation of graphene @xcite and subsequent experiments that reveal its special properties @xcite have generated excitement to explore the novel properties of the two dimensional ( 2d ) crystal from various disciplines .
advances in synthesis and experimental techniques enable the finding of other 2d crystals @xcite and the artificial fabrication of multiply - stacked structures @xcite . often , the stacking structures lead to very unusual electronic properties different from those of constituent 2d crystals depending on how they are piled up . among them , bilayer graphene ( blg ) , which is a stacked structure of two single - layer - graphene ( slg ) sheets , is unique in electronic structure and exhibits colorful variation in low energy states when its layer stacking is changed .
the in - plane three - fold rotational and mirror symmetries and the decoupling of strong @xmath0 and weak @xmath1 bondings of carbon atoms authorize the uniqueness of graphene systems . as such , the interlayer coupling in blg , while a weak van der waals type , produces interesting variations in low energy band....
And you have already written the first three sentences of the full article: figure 1 illustrates the sliding geometry of graphene layers in blg .
when the sliding vector @xmath2 is along @xmath3 , the blg gradually transforms from its pristine form of ab - stacking ( designated as ab - blg ) to aa - stacking ( @xmath4 ) in which all carbon atoms are right on top of each other ( aa - blg ) . for the sliding along @xmath5 ,
the ab - blg becomes upside - down ab - stacked blg ( ba - blg ) ..
Please generate the next two sentences of the article | equivalent layer stackings are arranged by other sliding vectors along either @xmath6 or @xmath7 direction .
also combination of the sliding vectors is possible as drawn in fig . |
7,247 | Suppose that you have an abstract for a scientific paper: we discuss a realistic high scale ( @xmath0 gev ) supersymmetric seesaw model based on the gauge group @xmath1 where neutron - anti - neutron oscillation can be in the observable range without fine tuning of parameters .
this is contrary to the naive dimensional arguments which say that @xmath2 and should therefore be unobservable for seesaw scale @xmath3 gev .
two reasons for this enhancement are : ( i ) accidental symmetries which keep some of the diquark higgs masses at the weak scale and ( ii ) a new supersymmetric contribution from a lower dimensional operator .
the net result is that @xmath4 rather than @xmath5 .
the model also can explain the origin of matter via the leptogenesis mechanism and predicts light diquark states which can be produced at lhc . .
And you have already written the first three sentences of the full article: there are various reasons to suspect that baryon number is not a good symmetry of nature : ( i ) first is that nonperturbative effects of the standard model lead to @xmath6 , while keeping @xmath7 @xcite ; ( ii ) understanding the origin of matter in the universe requires @xmath8 @xcite and ( iii ) many theories beyond the standard model lead to interactions that violate baryon number @xcite .
if indeed such interactions are there , the important question is : can we observe them in experiments@xmath9 ?
two interesting baryon nonconserving processes of experimental interest are : ( a ) proton decay e.g. @xmath10 etc @xcite and ( b ) @xmath11 oscillation @xcite . these two classes of processes probe two different selection rules for baryon nonconservation : @xmath7 for proton decay and @xmath12 for @xmath11 oscillation and indicate totally different directions for unification beyond the standard model ..
Please generate the next two sentences of the article | for example , observation of proton decay will point strongly towards a grand desert till about the scale of @xmath13 gev whereas @xmath11 oscillation will require new physics at an intermediate scale at or above the tev scale but much below the gut scale . while proton decay goes very naturally with the idea of eventual grand unification of forces and matter ,
recent discoveries of neutrino oscillations have made @xmath11 oscillation to be quite plausible theoretically if small neutrino masses are to be understood as a consequence of the seesaw mechanism @xcite . |
7,248 | Suppose that you have an abstract for a scientific paper: we show that the main features of the annual modulation of the signal expected in a wimp direct detection experiment , i.e. its sinusoidal dependence with time , the occurrence of its maxima and minima during the year and ( under some circumstances ) even the one year period , may be affected by relaxing the isothermal sphere hypothesis in the description of the wimp velocity phase space .
the most relevant effect is a distortion of the time
behaviour at low recoil energies for anisotropic galactic halos .
while some of these effects turn out to be relevant at recoil energies below the current detector thresholds , some others could already be measurable , although some degree of tuning between the wimp mass and the experimental parameters would be required .
either the observation or non observation of these effects could provide clues on the phase space distribution of our galactic halo . .
And you have already written the first three sentences of the full article: it is widely believed , as suggested by a host of independent cosmological and astrophysical observations , that the most part of the matter in the universe is not visible , revealing its existence only through gravitational effects .
in particular , data on the rotational curves of galaxies indicate that the galactic visible parts are surrounded by approximately spherical dark halos which extend up to several times the size of the luminous components .
the best candidates to provide dark matter in galaxies are weakly interacting massive particles ( wimp ) ..
Please generate the next two sentences of the article | several wimp direct detection experiments are operating @xcite , with the goal of measuring the nuclear recoil energy ( in the kev range ) expected to be deposited in solid , liquid or gaseous targets by the scattering of the non - relativistic dark halo wimps .
unfortunately , expected rates are small and the exponential decay of the wimp recoil spectrum resembles that of the background at low energies . |
7,249 | Suppose that you have an abstract for a scientific paper: we present in this talk a recent analysis for the magnetic moments of the baryon antidecuplet within the framework of the chiral quark - soliton model with linear @xmath0 corrections considered .
we take into account the mixing of higher representations to the collective magnetic moment operator , which comes from the su(3 ) symmetry breaking .
dynamical parameters of the model are fixed by experimental data for the magnetic moments of the baryon octet as well as by the masses of the octet , decuplet and of @xmath1 .
the magnetic moment of @xmath1 is rather sensitive to the pion - nucleon sigma term and ranges from @xmath2 to @xmath3 as the sigma term is varied from @xmath4 to @xmath5 mev , respectively . on top of them
, we obtained that the strange magnetic moment of the nucleon has the value of @xmath6 n.m . within this scheme and
turns out to be almost independent of the sigma term . .
And you have already written the first three sentences of the full article: exotic pentaquark baryons has been a hot issue , since the leps collaboration @xcite announced the new finding of the @xmath7 baryon @xmath8 which was soon confirmed by a number of other experiments @xcite , together with an observation of exotic @xmath9 states by the na49 experiment at cern @xcite , though it is still under debate .
those experiments searching for the pentaquark states was stimulated by diakonov et al .
@xcite : masses and decay widths of exotic baryon antidecuplet were predicted within the chiral quark - soliton model ..
Please generate the next two sentences of the article | the discoveries of the pentaquark baryon @xmath1 and possibly of @xmath10 have triggered intensive theoretical investigations ( see , for example , refs.@xcite ) .
the production mechanism of the @xmath1 has been discussed in refs.@xcite . in particular , it is of great interest to understand the photoproduction of the @xmath1 theoretically , since the leps and clas collaborations used photons as a probe to measure the @xmath1 . in order to describe the mechanism of the pentaquark photoproduction , we have to know the magnetic moment of the @xmath1 and its strong coupling constants . |
7,250 | Suppose that you have an abstract for a scientific paper: it has been recognized that the arc statistics of gravitational lensing is a useful probe of the density profile of clusters of galaxies .
we examine several systematic effects which are important in predicting the number of arcs , with particular attention to the difference between tangential and radial arcs .
first we derive an analytic expression of the cross section for radial arcs taking account of the source size and find that the moderate source size enhances the cross section for radial arcs while larger source size ( @xmath0 in our example ) suppresses the number of radial arcs . on the other hand , tangential arcs are much less sensitive to the source size .
next we numerically calculate the cross section for arcs considering the lens and source ellipticities .
we find that the numbers of both tangential and radial arcs are highly enhanced by both ellipticities , by one or two orders of magnitude .
the number ratio of radial to tangential arcs is , however , not so affected if the threshold axis ratio of arcs is large ( @xmath1 ) .
the number ratio therefore still remains good statistics which probe the density profile of the lens objects , if the source size effect is correctly taken into account . .
And you have already written the first three sentences of the full article: clusters of galaxies distort the images of background galaxies due to the gravitational lensing effect .
the statistics of such lensed arcs have been recognized as a powerful probe of the density profile of lens clusters @xcite . in particular , combined statistics of tangential and radial arcs are useful in determining the density profile of clusters @xcite .
a knowledge of the density profile is important because of recent indications that the cold dark matter scenario predicts a cuspy profile ( e.g. , * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ) while observations seem to prefer the existence of flat density cores ( e.g. , * ? ? ? |
7,251 | Suppose that you have an abstract for a scientific paper: we consider theoretically ionization of an atom by neutrino impact taking into account electromagnetic interactions predicted for massive neutrinos by theories beyond the standard model .
the effects of atomic recoil in this process are estimated using the one - electron and semiclassical approximations and are found to be unimportant unless the energy transfer is very close to the ionization threshold . we show that the energy scale where these effects become important is insignificant for current experiments searching for magnetic moments of reactor antineutrinos . neutrino - impact atomic ionization , atomic recoil , neutrino magnetic moments , bsm physics .
And you have already written the first three sentences of the full article: neutrinos are very intriguing objects in particle physics .
they interact very weakly and their masses are much smaller than those of the other fundamental fermions ( charged leptons and quarks ) . in the standard model ( sm ) , neutrinos are massless and have only weak interactions .
however , the observation of neutrino oscillations by many experiments implies that neutrinos are massive and mixed ..
Please generate the next two sentences of the article | therefore , the sm must be extended to account for neutrino masses . in many extensions of the sm
, neutrinos also acquire electromagnetic properties through quantum loop effects ( see refs . |
7,252 | Suppose that you have an abstract for a scientific paper: we present an ab initio study of the electronic stopping power of protons in copper over a wide range of proton velocities @xmath0 where we take into account non - linear effects .
time - dependent density functional theory coupled with molecular dynamics is used to study electronic excitations produced by energetic protons .
a plane - wave pseudopotential scheme is employed to solve the time - dependent kohn - sham equations for a moving ion in a periodic crystal .
the electronic excitations and the band structure determine the stopping power of the material and alter the interatomic forces for both channeling and off - channeling trajectories .
our off - channeling results are in quantitative agreement with experiments , and at low velocity they unveil a crossover region of superlinear velocity dependence ( with a power of @xmath1 ) in the velocity range @xmath2 , which we associate to the copper crystalline electronic band structure .
the results are rationalized by simple band models connecting two separate regimes .
we find that the limit of electronic stopping @xmath3 is not as simple as phenomenological models suggest and it plagued by band - structure effects . .
And you have already written the first three sentences of the full article: the interaction of charged particles with matter has been a subject of extensive research over many decades .
these studies provide information for many technological applications such as nuclear safety , applied material science , medical physics and fusion and fission applications @xcite . among the measurable quantities associated to the interaction between ions and solids ,
the stopping power @xmath4 @xcite has received much attention ; it provides information regarding the energy transfer between the incoming projectile and the solid target . when a fast ion moves through a material , it loses most of its kinetic energy due to the excitations of the target electrons along its trajectory in what constitutes a fundamentally non - adiabatic process ..
Please generate the next two sentences of the article | this energy - loss phenomenon plays an important role in many experimental studies involving radiation in solids , surfaces , and nanostructures @xcite .
various models and theories have been proposed to calculate stopping cross sections due to electrons . employing the first born approximation , |
7,253 | Suppose that you have an abstract for a scientific paper: we investigate generalized soliton bearing systems in the presence of external perturbations .
we show the possibility of the transport of solitons using external waves , provided the waveform and its velocity satisfy certain conditions .
we also investigate the stabilization and transport of bubbles using external perturbations in @xmath0systems .
we also present the results of real experiments with laser induced vapor bubbles in liquids . .
And you have already written the first three sentences of the full article: recently , in a very interesting paper , zheng _ et al . , _ @xcite have studied the collective directed transport of symmetrically coupled lattices in symmetric periodic potentials .
they show that under the action of an external wave , that breaks the spatiotemporal symmetry and introduces inhomogeneities of the lattice , a net unidirectional current can be observed .
apparently the current originates from the collaboration of the lattice and the wave ( amplitude , frequency , and phase shifts ) ..
Please generate the next two sentences of the article | the study of directed transport of particles is very important in the physics of molecular motors @xcite , vortex dynamics in superconductors @xcite , josephson junction lattices @xcite , nanotechnology @xcite and many other systems .
many studies have been dedicated to directed transport in spatiotemporal systems @xcite . |
7,254 | Suppose that you have an abstract for a scientific paper: we propose a secure transmission scheme for a relay wiretap channel , where a source communicates with a destination via a decode - and - forward relay in the presence of spatially random - distributed eavesdroppers .
we assume that the source is equipped with multiple antennas , whereas the relay , the destination , and the eavesdroppers are equipped with a single antenna each . in the proposed scheme , in addition to information signals ,
the source transmits artificial noise signals in order to confuse the eavesdroppers . with the target of maximizing the secrecy throughput of the relay wiretap channel
, we derive a closed - form expression for the transmission outage probability and an easy - to - compute expression for the secrecy outage probability . using these expressions
, we determine the optimal power allocation factor and wiretap code rates that guarantee the maximum secrecy throughput , while satisfying a secrecy outage probability constraint . furthermore , we examine the impact of source antenna number on the secrecy throughput , showing that adding extra transmit antennas at the source brings about a significant increase in the secrecy throughput . .
And you have already written the first three sentences of the full article: wireless communications are inherently insecure , due to the broadcast nature of the medium , which makes security a pivotal design issue in the implementation and operation of current and future wireless networks . compared to the traditional key - based cryptographic techniques that are applied to upper layers , physical layer security can enhance the secrecy of wireless communications without using secret keys and complex encryption / decryption algorithms , and thus has been recognized as an alternative for cryptographic techniques .
the key idea of physical layer security is to exploit the randomness of wireless channels to offer secure data transmissions @xcite . in early studies , e.g. , @xcite , the principle of physical layer security
was established in a single - input single - output wiretap channel ..
Please generate the next two sentences of the article | subsequently , physical layer security in multi - input multi - output ( mimo ) communication systems has been intensively investigated @xcite , due to the benefits of mimo techniques such as high data rate and high link reliability .
most recently , physical layer security in large - scale wireless networks , such as mobile ad hoc and sensor networks , has been receiving considerable attention @xcite . |
7,255 | Suppose that you have an abstract for a scientific paper: this article gives a sketch of teachers and colleagues who have had strong influence on my becoming a particle theorist . .
And you have already written the first three sentences of the full article: the war ended on august 15 , 1945 .
although large areas of tokyo had been reduced to ashes by the intense bombing , tokyo imperial university ( todai ) was luckily spared from destruction .
however , life in the tokyo area had become very difficult , because of the extreme shortage of housing and the breakdown of the food - rationing system , established during the war , in the postwar confusion ..
Please generate the next two sentences of the article | todai was closed until the end of 1945 , and students went back to their homes in the countryside .
todai reopened in january 1946 . |
7,256 | Suppose that you have an abstract for a scientific paper: we present ground - based optical and _ spitzer space telescope _
infrared imaging observations of the ecliptic ( jupiter - family ) comet 21p / giacobini - zinner , the parent body of the draconid meteor stream , during its 2005 apparition . onset of nucleus activity occurred at a pre - perihelion heliocentric distance , @xmath0 au , while post - perihelion 21p was dusty ( peak @xmath1 @xmath2 ) and active out to heliocentric distances @xmath3 au following a logarithmic slope with @xmath4 of @xmath5 .
coma colors , @xmath6 are redder than solar , yet comparable to colors derived for other jupiter - family comets . a nucleus radius of @xmath7 km is derived from photometry at quiescence . _
spitzer _ images post - perihelion exhibit an extensive coma with a prominent dust tail , where excess emission ( over the dust continuum ) in the 4.5 irac image arises from volatile gaseous co and/or co@xmath8 .
no dust trail was detected ( @xmath9 surface brightness upper - limit of 0.3 mjy sr@xmath10 pixel@xmath10 ) along the projected velocity vector of comet 21p in the mips 24 image suggesting that the number density of trail particles is @xmath11 m@xmath12 .
the bolometric albedo of 21p derived from the contemporaneous optical and _ spitzer _ observations is @xmath13 , slightly lower than values derived for other comets at the same phase angle . .
And you have already written the first three sentences of the full article: comet nuclei formed beyond the protoplanetary disk frost line ( heliocentric distances , @xmath4 5 au ; * ? ? ?
* ) , among the giant planets and were scattered into the kuiper belt and beyond into the oort cloud ( oc ) . since their formation
, the interiors and surfaces of most comets have remained at temperatures below 140 k while in `` cold storage '' in the kuiper belt or the oc @xcite ..
Please generate the next two sentences of the article | moreover , most nucleus surfaces have remained below 400 k even during perihelion passage . at such low temperatures ,
dust mineralogy remains stable and each comet nucleus retains a record of the minerals , ices , and volatiles extant in the comet agglomeration zones in the early solar system . |
7,257 | Suppose that you have an abstract for a scientific paper: on the basis of detailed _ ab initio _ studies the influence of strain on the anisotropy of the transport distribution of the thermoelectrics bi@xmath0te@xmath1 and sb@xmath0te@xmath1 was investigated .
both tellurides were studied in their own , as well as in their co - partners lattice structure to gain insight to the electrical transport in epitaxial heterostructures composed of both materials .
it is shown , that the anisotropy of the transport distribution overestimates the experimental findings for bi@xmath0te@xmath1 , implying anisotropic scattering effects .
an increase of the in - plane lattice constant leads to an enhancement of the transport anisotropy for @xmath2-doping , whereas the opposite occurs for @xmath3-doping .
the recent findings and special features of the transport distribution are discussed in detail in relation to the topology of the band structures . .
And you have already written the first three sentences of the full article: thermoelectric ( te ) materials have huge potential for power generation , heat pumping , and refrigeration . however , their practical application is restricted because of the low performance of the te devices compared to traditional fossil fuel power generators and compressor - based refrigerators @xcite .
a high performance te material has to be a good electrical conductor as well as a poor thermal conductor and , at the same time , possess a large seebeck coefficient@xcite .
quantitatively the efficiency of te devices is expressed by the dimensionless figure of merit @xmath4 , @xmath5 where @xmath6 , @xmath7 , @xmath8 are the seebeck coefficient , electrical conductivity and absolute temperature , and @xmath9 , @xmath10 are phonon and electron contributions to the total thermal conductivity , respectively ..
Please generate the next two sentences of the article | bismuth and antimony tellurides , bi@xmath0te@xmath1 , sb@xmath0te@xmath1 , and the alloys based on these materials play a significant role for thermoelectric technology .
already early studies of the ( bi@xmath11,sb@xmath12)te@xmath1 compounds in the late 1950s reported @xmath13 at room temperature @xcite , confirmed by further experiments @xcite . |
7,258 | Suppose that you have an abstract for a scientific paper: -.35 in we use the high energy predictions of a qcd - inspired parameterization of all accelerator data on forward proton - proton and antiproton - proton scattering amplitudes , along with glauber theory , to predict proton
air cross sections at energies near @xmath0 30 tev .
the parameterization of the proton - proton cross section incorporates analyticity and unitarity , and demands that the asymptotic proton is a black disk of soft partons . by comparing with the p - air cosmic ray measurements , our analysis results in a constraint on the inclusive particle production cross section .
@=11
@=12 .65 in cosmic ray experiments measure the penetration in the atmosphere of particles with energies in excess of those accelerated by existing machines interestingly , their energy range covers the energy of the large hadron collider ( lhc ) and extends beyond it .
however , extracting proton proton cross sections from cosmic ray observations is far from straightforward @xcite . by a variety of experimental techniques , cosmic ray experiments
map the atmospheric depth at which cosmic ray initiated showers develop .
the measured shower attenuation length ( @xmath1 ) is not only sensitive to the interaction length of the protons in the atmosphere ( @xmath2 ) , with @xmath3 but also depends on the rate at which the energy of the primary proton is dissipated into electromagnetic shower energy observed in the experiment .
the latter effect is parameterized in eq.([eq : lambda_m ] ) by the parameter @xmath4 ; @xmath5 is the proton mass and @xmath6 the inelastic proton - air cross section .
the value of @xmath4 depends on the inclusive particle production cross section in nucleon and meson interactions on the light nuclear target of the atmosphere and its energy dependence .
we here ignored the fact that particles in the cosmic ray `` beam '' may be nuclei , not just protons .
experiments allow for this by omitting from their analysis showers which dissipate their energy high in the....
And you have already written the first three sentences of the full article: this research was supported in part by the u.s .
department of energy under grants no . da - ac02 - 76-er02289 task b and no .
de - fg02 - 95er40896 and in part by the university of wisconsin research committee with funds granted by the wisconsin alumni research foundation ..
Please generate the next two sentences of the article | the research of ts is supported in part by the u.s .
department of energy under grant no . |
7,259 | Suppose that you have an abstract for a scientific paper: the electron doping of undoped high-@xmath0 cuprates via the transfer of charge from manganites ( or other oxides ) using heterostructure geometries is here theoretically discussed .
this possibility is mainly addressed via a detailed analysis of photoemission and diffusion voltage experiments , which locate the fermi level of manganites above the bottom of the upper hubbard band of some cuprate parent compounds . a diagram with the relative location of fermi levels and gaps for several oxides
is presented .
the procedure discussed here is generic , allowing for the qualitative prediction of the charge flow direction at several oxide interfaces .
the addition of electrons to antiferromagnetic cu oxides may lead to a superconducting state at the interface with minimal quenched disorder .
model calculations using static and dynamical mean - field theory , supplemented by a poisson equation formalism to address charge redistribution at the interface , support this view .
the magnetic state of the manganites could be antiferromagnetic or ferromagnetic .
the former is better to induce superconductivity than the latter , since the spin - polarized charge transfer will be detrimental to singlet superconductivity .
it is concluded that in spite of the robust hubbard gaps , the electron doping of undoped cuprates at interfaces appears possible , and its realization may open an exciting area of research in oxide heterostructures . .
And you have already written the first three sentences of the full article: the study of oxide heterostructures is rapidly developing into one of the most promising areas of research in strongly correlated electronic systems .
the current excitement in this field was in part triggered by the recent discovery of conducting interfaces , with a substantial high carrier mobility , between two insulating perovskites @xcite .
these results were obtained by growing abrupt layers of the insulators lati(3+)o@xmath1 and srti(4+)o@xmath1 ..
Please generate the next two sentences of the article | when the spatial distribution of the extra electron was observed with an atomic - scale electron beam , it was found to correspond to a metallic state at the interface @xcite .
theoretical investigations of these systems @xcite , using hartree - fock and dmft techniques , concluded that the leakage of charge from one layer to the other explains the results . |
7,260 | Suppose that you have an abstract for a scientific paper: the phase diagram of the metal - insulator transition in a three dimensional quantum percolation problem is investigated numerically based on the multifractal analysis of the eigenstates .
the large scale numerical simulation has been performed on systems with linear sizes up to @xmath0 .
the multifractal dimensions , exponents @xmath1 and @xmath2 , have been determined in the range of @xmath3 .
our results confirm that this problem belongs to the same universality class as the three dimensional anderson model , the critical exponent of the localization length was found to be @xmath4 .
however , the mulifractal function , @xmath5 , and the exponents @xmath1 and @xmath2 produced anomalous variations along the phase boundary , @xmath6 . .
And you have already written the first three sentences of the full article: the disorder induced metal - insulator transition , a genuine quantum phase transition is one of the most studied phenomena of condensed matter physics since the seminal paper published over five decades ago . @xcite according to the original problem , the hamiltonian @xmath7 describes the behavior of non - interacting spinless electrons in disorder . the first term in eq .
( [ eq : am ] ) represents an onsite disordered potential , where the energies , @xmath8 , are independent , uncorrelated random variables , drawn from a distribution function , @xmath9 , whose form is usually chosen to be uniform over an energy range that is symmetric around @xmath10 , but other forms , e.g. gaussian or binary distributions could be used , as well . the second term in eq .
( [ eq : am ] ) is the kinetic energy describing the hopping of the particles over a regular lattice , but restricted to nearest neighbors only ..
Please generate the next two sentences of the article | the energy scale associated to the hopping process , @xmath11 , can be taken as the unit of energy ( @xmath12 ) .
the sites form a regular , usually simple cubic lattice . |
7,261 | Suppose that you have an abstract for a scientific paper: we discuss the stability properties of the solutions of the general nonlinear schrdinger equation ( nlse ) in 1 + 1 dimensions in an external potential derivable from a parity - time ( @xmath0 ) symmetric superpotential @xmath1 that we considered earlier [ kevrekidis _ et al .
_ phys .
rev .
e * 92 * , 042901 ( 2015 ) ] .
in particular we consider the nonlinear partial differential equation @xmath2 for arbitrary nonlinearity parameter @xmath3 .
we study the bound state solutions when @xmath4 , which can be derived from two different superpotentials @xmath1 , one of which is complex and @xmath0 symmetric . using derrick s theorem , as well as a time dependent variational approximation ,
we derive exact analytic results for the domain of stability of the trapped solution as a function of the depth @xmath5 of the external potential .
we compare the regime of stability found from these analytic approaches with a numerical linear stability analysis using a variant of the vakhitov - kolokolov ( v k ) stability criterion .
the numerical results of applying the v - k condition give the _ same _ answer for the domain of stability as the analytic result obtained from applying derrick s theorem .
our main result is that for @xmath6 a _ new _ regime of stability for the exact solutions appears as long as @xmath7 , where @xmath8 is a function of the nonlinearity parameter @xmath3 . in the absence of the potential the related solitary wave solutions of the nlse are _ unstable _ for @xmath6 . .
And you have already written the first three sentences of the full article: the topic of parity - time ( @xmath9 ) symmetry and its relevance for physical applications on the one hand , as well as its mathematical structure on the other , have drawn considerable attention from both the physics and the mathematics community .
originally the proposal of bender and his collaborators @xcite towards the study of such systems was made as an alternative to the postulate of hermiticity in quantum mechanics . in view of the formal similarity of the schrdinger equation with maxwell s equations in the paraxial approximation
, it was realized that such @xmath9 invariant systems can in fact be experimentally realized in optics @xcite ..
Please generate the next two sentences of the article | subsequently , these efforts motivated experiments in several other areas including @xmath9 invariant electronic circuits @xcite , mechanical circuits @xcite , and whispering - gallery microcavities @xcite .
concurrently , the notion of supersymmetry ( susy ) originally espoused in high - energy physics has also been realized in optics @xcite . |
7,262 | Suppose that you have an abstract for a scientific paper: we study two - body decays of a new neutral pseudoscalar into gauge bosons within the context of the littlest higgs model .
concretely , the @xmath0 processes induced at the one - loop level , with @xmath1 , are considered .
since the branching ratios of the @xmath2 decays result very suppressed , only the @xmath3 processes are thoroughly studied .
the branching ratios for the @xmath4 and @xmath5 decays are of the order of @xmath6 and @xmath7 , respectively , for @xmath8 around 2 tev , which represents the global symmetry breaking scale of the theory .
the production cross section of the @xmath9 boson via gluon fusion at lhc is estimated . .
And you have already written the first three sentences of the full article: after the discovery of the higgs boson , the atlas @xcite and cms @xcite collaborations have continued searching for new exotic particles , such as the randall - sundrum spin-2 boson or new heavy scalar particles @xcite .
particularly , atlas collaboration is carrying out searches for new scalar resonances decaying into two photons .
though up to the moment the searches for new scalar resonances has been fruitless , it is expected that the experimental collaborations atlas and cms continue the seek for new particles at the tev energy scale ..
Please generate the next two sentences of the article | these quests are supported by the improvements implemented in the cms and atlas detectors @xcite along with the fact that the experimental collaborations have been able to develop a reliable detection machinery of spin-0 resonances .
thus , the perspectives of searching for new physics phenomena at the tevs scale are hopeful . |
7,263 | Suppose that you have an abstract for a scientific paper: we find concrete evidence for the presence of crisis induced and pomeau manneville type - i intermittencies in an axisymmetric pde mean field dynamo model .
these findings are of potential importance for two different reasons .
firstly , as far as we are aware , this is the first time detailed evidence has been produced for the occurrence of these types of intermittency for such deterministic pde models . and secondly , despite the rather idealised nature of these models , the concrete evidence for the occurrence of more than one type of intermittency in such models makes it in principle possible that different types of intermittency may occur in different solar - type stars or even in the same star over different epochs . in this way a
_ multiple intermittency framework _ may turn out to be of importance in understanding the mechanisms responsible for grand - minima type behaviour in the sun and solar - type stars and in particular in the interpretation of the corresponding observational and proxy evidence . .
And you have already written the first three sentences of the full article: intermittency has been observed in a variety of real settings as well in a vast number of numerical models
. a great deal of effort has therefore gone into understanding these modes of behaviour in the context of deterministic dynamical systems theory .
these studies have demonstrated the existence of a number of different types of intermittency ( such as pomeau .
Please generate the next two sentences of the article | manneville @xcite , crisis @xcite , on - off @xcite intermittencies ) , each with their own associated signatures and scalings .
many of these forms of intermittency have in turn been concretely shown to be present in experiments and numerical studies of dynamical systems in a variety of settings ( see @xcite and references therein ) . |
7,264 | Suppose that you have an abstract for a scientific paper: we report on the optical properties of single inas / gaas quantum dots emitting near the telecommunication o - band , probed via coulomb blockade and non - resonant photoluminescence spectroscopy , in the presence of external electric and magnetic fields .
we extract the physical properties of the electron and hole wavefunctions , including the confinement energies , interaction energies , wavefunction lengths , and @xmath0-factors . for excitons ,
we measure the permanent dipole moment , polarizability , diamagnetic coefficient , and zeeman splitting .
the carriers are determined to be in the strong confinement regime .
large range electric field tunability , up to 7 mev , is demonstrated for excitons .
we observe a large reduction , up to one order of magnitude , in the diamagnetic coefficient when rotating the magnetic field from faraday to voigt geometry due to the unique dot morphology .
the complete spectroscopic characterization of the fundamental properties of long - wavelength dot - in - a - well structures provides insight for the applicability of quantum technologies based on quantum dots emitting at telecom wavelengths . .
And you have already written the first three sentences of the full article: single quantum dots grown by molecular beam epitaxy are one of the most promising sources of non - classical light due to their stable and sharp emission lines and easy integration on a chip via the mature iii - v semiconductor fabrication technology . in particular , inas quantum dots emitting at wavelengths around 950 nm have proved to be pure sources of single indistinguishable photons @xcite and entangled photons @xcite and a powerful platform for spin initialization and manipulation , spin - photon and remote spin entanglement @xcite . to encode information in single photons and transmit it over long distances , sources of quantum light emitting at the so - called telecommunication wavelengths are most desirable .
advances in the development of superconducting detectors operating at cryogenic temperatures @xcite allow detection efficiencies exceeding 90% @xcite , making single - photon experiments and technologies eminently feasible .
the growing interest in the field of long wavelength quantum dots is demonstrated by recent achievements such as the demonstration of bright sources of indistinguishable photons @xcite , interference of photons emitted by dissimilar sources @xcite , entangled photon pair generation @xcite and exciton fine - structure splitting manipulation @xcite in the telecom wavelength band . however , the growth and fundamental characterisation of quantum dots emitting at telecom wavelengths is less mature compared to emitters at wavelengths @xmath1 1 @xmath2 m ..
Please generate the next two sentences of the article | the longer emission wavelength can be achieved by growing quantum dots in a quantum well ( the so - called dot - in - a - well or dwell structures @xcite ) , a technique that partially relaxes the strain accumulated during the stranski - krastanow growth , resulting in larger quantum dot dimensions .
the ingaas quantum well provides local strain relief and also preserves the quantum dot composition and height during growth by reducing the out - diffusion of in during capping of the dot layer @xcite . |
7,265 | Suppose that you have an abstract for a scientific paper: in this work we prove that each @xmath0 conservative diffeomorphism with a pair of hyperbolic periodic points of co - index one can be @xmath1-approximated by @xmath0 conservative diffeomorphisms having a blender . .
And you have already written the first three sentences of the full article: one major task in the theory of dynamics is to establish some kind of dynamic irreducibility of a system . of principal interest
are the systems that display some kind of persistent irreducibility .
the two main examples of this concept are robust transitivity and stable ergodicity ..
Please generate the next two sentences of the article | blenders were introduced by c. bonatti and l. daz in @xcite , to produce a large class of examples of non - hyperbolic robustly transitive diffeomorphisms .
there , they showed that these objects appeared in a neighborhood of the time - one map of any transitive anosov flow . |
7,266 | Suppose that you have an abstract for a scientific paper: we give under weak assumptions a complete combinatorial characterization of identifiability for linear mixtures of finite alphabet sources , with unknown mixing weights and unknown source signals , but known alphabet .
this is based on a detailed treatment of the case of a single linear mixture .
notably , our identifiability analysis applies also to the case of unknown number of sources .
we provide sufficient and necessary conditions for identifiabilty and give a simple sufficient criterion together with an explicit construction to determine the weights and the source signals for deterministic data by taking advantage of the hierarchical structure within the possible mixture values .
we show that the probability of identifiability is related to the distribution of a hitting time and converges exponentially fast to one when the underlying sources come from a discrete markov process .
finally , we explore our theoretical results in a simulation study .
our work extends and clarifies the scope of scenarios for which blind source separation becomes meaningful .
blind source separation ; bss ; finite alphabet signals ; single mixture ; instantaneous mixtures ; markov processes , stopping time .
And you have already written the first three sentences of the full article: in this work we are concerned with identifiability in a particular kind of blind source separation ( bss ) motivated by different applications in digital communication ( see e.g.,@xcite ) , but also in cancer genetics ( see e.g.,@xcite ) . a prominent example is the separation of a mixture of audio or speech signals , which has been picked up by several microphones , simultaneously ( see e.g. , @xcite ) . in this case
the different speech signals correspond to the sources and the recordings of the microphones to the mixture of signals with unknown mixture weights . from this mixture
the individual signals have to be separated ..
Please generate the next two sentences of the article | more generally , in bss problems one observes @xmath0 mixtures of @xmath1 sources and aims to recover the original sources from the available observations . in this paper
we focus on the linear case ( for the non - linear case see e.g. , @xcite ) , where the blindness refers to the fact that neither the sources nor the mixing weights are known . |
7,267 | Suppose that you have an abstract for a scientific paper: in this work we present a new family of options ( mirror options ) specially crafted to satisfy the necessities of aggressive speculators .
the main ideas behind mirror options are : 1 ) a product that can be adjusted by the holder to agree with his / her market view at any time during its life .
2 ) the holder s right to make an arbitrary number of those adjustments without penalizing costs . after defining mirror options as ` super - versions ' of standard options
we derive general formulae for their value in the case where the payoff is a monotonic function of the underlying ( which is the case in calls , puts , futures , spreads etc . ) .
we briefly discuss also their valuation for general payoffs and the american case .
finally we analyze the situation where the number of allowed adjustments is restricted and we point out directions for further developments . 155 mm -15pt .
And you have already written the first three sentences of the full article: since the first options on stocks appeared in an organized exchange ( the cboe ) in 1973 there has been a continuous growth in worldwide option markets .
this growth is not only apparent in the increasing volumes of options traded in organized and otc markets but also in the never ending production of new products providing alternatives to satisfy the necessities of investors , banks and other financial institutions @xcite .
these necessities may include risk transference , speculative leveraging , portfolio diversification , etc ..
Please generate the next two sentences of the article | the purpose of this article is to present a new family of options specially designed to satisfy the necessities of speculators .
nowadays we have at our disposal a wide spectrum of products that can virtually serve at whatever market view that a speculator may have . |
7,268 | Suppose that you have an abstract for a scientific paper: we evaluate the @xmath0 coupling constant using a qcd sum rule based on the pion - to - vacuum matrix element of the correlator of two interpolating nucleon fields .
the part of the correlator with dirac structure @xmath1 is used , keeping all terms up to dimension 5 in the ope and including continuum contributions on the phenomenological side .
the ratio of this sum rule to the nucleon sum rule involving condensates of odd dimension yields stable results with values of @xmath2 in the range @xmath3 .
the sources of uncertainty are discussed .
understanding hadron interactions from first principles is one of the main goals of quantum chromodynamics ( qcd ) .
since the solution of qcd for hadron interactions at low energies is still far off it is useful to consider tackle problems of hadron dynamics with approaches that lie as close as possible to qcd .
one of them , the method of qcd sum rules@xcite , has proved to be a very powerful tool to extract information about hadron properties .
we present here a sum rule analysis of the @xmath0 coupling constant @xmath4 , which is one of the most important parameters in hadron physics .
this quantity has previously been examined within the framework of qcd sum rules in refs .
@xcite .
reinders , rubinstein and yazaki @xcite worked with two different sum rules for @xmath2 , one obtained from a correlator of three interpolating fields , and one based on the pion - to - vacuum matrix element of the correlator of two interpolating nucleon fields , @xmath5 : @xmath6 however those authors included only the leading term of operator product expansion ( ope ) and neglected continuum contributions .
shiomi and hatsuda@xcite developed the sum rule based on the part of this two - point correlation function with dirac structure @xmath7 .
they calculated @xmath4 in the soft - pion limit , including condensates up to dimension 7 in the ope , radiative corrections and a perturbative estimate of continuum contributions .
the method based on the two....
And you have already written the first three sentences of the full article: we are grateful to v. kartvelishvili for useful discussions .
this work was supported by the epsrc and pparc .
999 m. a. shifman , a. i. vainshtein and v. i. zakharov , nucl ..
Please generate the next two sentences of the article | * b147 * ( 1979 ) 385 , 448 . l. j. reinders , h. rubinstein and s. yazaki , phys .
reports * 127 * ( 1985 ) 1 . |
7,269 | Suppose that you have an abstract for a scientific paper: two familiar notions of correlation are rediscovered as extreme operating points for simulating a discrete memoryless channel , in which a channel output is generated based only on a description of the channel input .
wyner s `` common information '' coincides with the minimum description rate needed .
however , when common randomness independent of the input is available , the necessary description rate reduces to shannon s mutual information .
this work characterizes the optimal tradeoff between the amount of common randomness used and the required rate of description . .
And you have already written the first three sentences of the full article: what is the intrinsic connection between correlated random variables ? how much interaction is necessary to create correlation ?
many fruitful efforts have been made to quantify correlation between two random variables .
each quantity is justified by the operational questions that it answers ..
Please generate the next two sentences of the article | covariance dictates the mean squared error in linear estimation .
shannon s mutual information is the descriptive savings from side information in lossless source coding and the additional growth rate of wealth due to side information in investing . |
7,270 | Suppose that you have an abstract for a scientific paper: the evidence presented earlier by several authors for the substantial disk eccentricity in dwarf novae during their superoutbursts is shown to result either from errors , or from arbitrary , incorrect assumptions .
\(1 ) the evidence for z cha and wz sge ( vogt 1981 ) , based on radial velocities measured from absorption components , was an artifact , resulting from miscalculated beat phases .
\(2 ) the evidence for oy car ( krzemiski and vogt 1985 ) and iy uma ( patterson et al . 2000 ) , based on the observed dependence of eclipse parameters on the beat phase , involved an implicit assumption that the observed eclipses are _ pure disk _ eclipses , which is not true .
in particular , the observed variations of eclipse parameters are likely due to the contributions from the hot spot and from the superhump source , which depend strongly on the beat phase .
\(3 ) the evidence for oy car ( hessman et al 1992 ) and wz sge ( patterson et al . 2002 ) , resulting from the analysis of hot spot eclipses , was based on the assumption that the spot distances are identical with the radius of the disk , which is not always correct . in particular , in the case of eclipses of `` peculiar '' spots ( involving the stream overflow ) , observed at beat phases away from @xmath0 , the resulting spot distances are smaller that the radius of the disk .
new determination of disk eccentricity in z cha , using vogt s radial velocities measured from emission components , gives @xmath1 .
* key words : * _ accretion , accretion disks binaries : cataclysmic variables , stars : dwarf novae , stars : individual : oy car , z cha , wz sge , iy uma _ .
And you have already written the first three sentences of the full article: the concept of an eccentric , `` precessing '' disk was a crucial ingredient of the tidal - thermal instability model of superoutbursts proposed by osaki ( 1996 , 2005 and references therein ) .
results of recent analysis of superoutbursts of z cha ( smak 2007 , 2008a ) definitely show , however , that superoutbursts are due to a major enhancement in the mass transfer rate .
it is worth to recall that an alternative model for superoutbursts , involving such enhanced mass transfer resulting from variable irradiation of the secondary component , was considered earlier by osaki himself ( osaki 1985 ; see also mineshige 1988 ) ..
Please generate the next two sentences of the article | further work in this direction appears now highly desirable .
eccentric , `` precessing '' disk continues to be an essential ingredient of the commonly accepted model for superhumps ( see also osaki 1996 , 2005 and references therein ) . |
7,271 | Suppose that you have an abstract for a scientific paper: i review the theoretical ideas and concepts along the line of factorization in the exclusive b decays . in order to understand the naive factorization ,
the effective field theories and the perturbative method of qcd are introduced and developed .
we focus our discussions on the large energy effective theory , the qcd factorization approach and the soft - collinear effective theory . .
And you have already written the first three sentences of the full article: the exploration of cp violation and determination of the cabibbo - kobayashi - maskawa ( ckm ) matrix elements motivate extensive interests of b meson decay . from another point of view
, b decays provide a good place to study the fruitful dynamics of qcd . up to now
, we have not a truly successful method to calculate the non - perturbative qcd and the mechanism of quark confinement is still unknown ..
Please generate the next two sentences of the article | the study of exclusive b decays is usually difficult because of the complicate qcd dynamics .
however , the experiments from the belle and babar collaborations have accumulated and will continue to accumulate a large amount of data of b decays . |
7,272 | Suppose that you have an abstract for a scientific paper: the existence of a massive black hole in the center of the milky way , coinciding with the radio source sgr a * , is being established on more and more solid ground . in principle , this black hole , acting as a gravitational lens , is able to bend the light emitted by stars moving within its neighborhood , eventually generating secondary images . extending a previous analysis of the gravitational lensing phenomenology to a new set of 28 stars , whose
orbits have been well determined by recent observations , we have calculated all the properties of their secondary images , including time and magnitude of their luminosity peaks and their angular distances from the central black hole . the best lensing candidate is represented by the star s6 , since the magnitude of its secondary image at the peak reaches @xmath0 , with an angular separation of 0.3 mas from the central black hole , that is just at the borders of the resolution limit in the @xmath1 band of incoming astronomical instruments . .
And you have already written the first three sentences of the full article: one of the most fascinating arenas for testing general relativity in the neighborhood of a real astrophysical black hole is undoubtedly represented by sgr a * , the massive black hole ( mbh ) at the center of our galaxy , whose existence has been now strongly proven by the combination of radio , sub - mm , x - ray , and near infrared ( nir ) observations . while in the radio domain sgr a * appears as a steady and motionless compact source @xcite , its x - ray , sub - mm , and nir counterparts are variable since they exhibit outbursts of energy ( _ flares _ ) , which typically last for a few hours and occur several times a day @xcite .
these flares are likely due to energetic events arising very close to the central mbh , on a scale of a few schwarzschild radii , and they can be interpreted as due to emission from matter in relativistic orbits around sgr a*. moreover , by using large class telescopes , such as the eso very large telescope ( vlt ) and the keck telescopes , and thanks to the adaptive optics , it has been possible to observe a multitude of stars in the @xmath1 band ( the so - called s - stars ) moving in the gravitational potential of the galactic mbh @xcite .
the entire system is perfectly described by a single point mass and newton gravity ..
Please generate the next two sentences of the article | very recently , @xcite have been able to determine the orbits of 28 s - stars , resting upon the results of 16 years of monitoring of their motions . in particular , it has been possible to observe the whole orbit of the famous star s2 , since it has completed a full revolution around sgr a*. the value of the galactic mbh mass , extrapolated from these improved data , is @xmath2 m@xmath3 . since the theory of general relativity predicts that the central mbh can act as a powerful gravitational lens on s - stars , some of them , depending on the knowledge of their orbital parameters , have been the object of careful investigations .
the strategy of this study is very clear . |
7,273 | Suppose that you have an abstract for a scientific paper: hadron molecules are particles made out of hadrons that are held together by self interactions . in this report
we discuss seven such molecules and their self interactions .
the @xmath0 , @xmath1 , @xmath2 , @xmath3 and @xmath4 molecular structure is given .
we predict that two more states the @xmath5 and @xmath6 should be found .
= 0.4 cm = 0.0 in = 0.0 in = 9.0 in = 6.5 in = 0.1 in + .
And you have already written the first three sentences of the full article: the first two molecular states @xmath0 and @xmath1 are the isosinglet and the isotriplet states of the @xmath7@xmath8 bound system@xcite .
this binding requires a quark - spin hyperfine interaction in the over all @xmath9 @xmath9 @xmath10 @xmath10 system .
we will see that this binding is different from the particle exchange mechanisms that bind the rest of molecules of this report ..
Please generate the next two sentences of the article | the exchanges of ref.@xcite that bind the @xmath7@xmath8 system are quark exchanges where the quark - spin hyperfine interaction leads to an attractive potential .
this attractive potential can only make states if the mesons of the fall apart mode @xmath9 @xmath10 - @xmath9 @xmath10 are below threshold . |
7,274 | Suppose that you have an abstract for a scientific paper: we analyze the fast transient dynamics of a multi - longitudinal mode semiconductor laser on the basis of a model with intensity coupling .
the dynamics , coupled to the constraints of the system and the below - threshold initial conditions , imposes a faster growth of the side modes in the initial stages of the transient , thereby leading the laser through a sequence of states where the modal intensity distribution dramatically differs from the asymptotic one . a detailed analysis of the below - threshold
, deterministic dynamical evolution allows us to explain the modal dynamics in the strongly coupled regime where the total intensity peak and relaxation oscillations take place , thus providing an explanation for the modal dynamics observed in the slow , hidden evolution towards the asymptotic state ( cf .
phys .
rev .
a * 85 * , 043823 ( 2012 ) ) .
the dynamics of this system can be interpreted as the transient response of a driven , globally coupled ensemble of nonlinear modes evolving towards an equilibrium state .
since the qualitative dynamics do not depend on the details of the interaction but only on the structure of the coupling , our results hold for a whole class of globally , bilinearly coupled oscillators .
( all figures in color online ) . .
And you have already written the first three sentences of the full article: the transient turn - on dynamics of lasers is a topic which has received a considerable amount of attention over the years ( cf .
, e.g. , @xcite ) , not only for the fundamental understanding of its evolution but also , and especially , for the importance that it represents in data encoding in telecommunications with directly - modulated semiconductor lasers . while multiple quantum well @xcite ( or even quantum dot @xcite ) lasers have been proven to possess a peculiar modal dynamics
modelled with the help of mutual nonlinear coupling and noise @xcite , with a complex ginzburg - landau approach @xcite or based on multiscale analysis @xcite where the resulting model provides proof for a true phase instability @xcite , inexpensive , edge - emitting devices show a dynamics @xcite which is more appropriately characterized by cooperation , rather than competition @xcite . for these latter devices ,.
Please generate the next two sentences of the article | we have recently shown @xcite that a realistic model for a multimode semiconductor laser , with experimentally matched parameters @xcite , predicts a slow , hidden dynamical mode - evolution governed by a master mode .
an overall agreement exists between our recent predictions and a wealth of experimental data ( e.g. @xcite ) since it has been time and again shown that a gradual line narrowing exists in the progress of the multimode laser transient ( cf . also previous theoretical calculations , e.g. , @xcite ) . |
7,275 | Suppose that you have an abstract for a scientific paper: we present a new first - order approach to strain - engineering of graphene s electronic structure where no continuous displacement field @xmath0 is required .
the approach is valid for negligible curvature .
the theory is directly expressed in terms of atomic displacements under mechanical load , such that one can determine if mechanical strain is varying smoothly at each unit cell , and the extent to which sublattice symmetry holds . since strain deforms lattice vectors at each unit cell ,
orthogonality between lattice and reciprocal lattice vectors leads to renormalization of the reciprocal lattice vectors as well , making the @xmath1 and @xmath2 points shift in opposite directions . from this observation
we conclude that no @xmath3dependent gauges enter on a first - order theory . in this formulation of the theory
the deformation potential and pseudo - magnetic field take discrete values at each graphene unit cell .
we illustrate the formalism by providing strain - generated fields and local density of electronic states on graphene membranes with large numbers of atoms .
the present method complements and goes beyond the prevalent approach , where strain engineering in graphene is based upon first - order continuum elasticity . .
And you have already written the first three sentences of the full article: the interplay between mechanical and electronic effects in carbon nanostructures has been studied for a long time ( e.g. , @xcite ) .
the mechanics in those studies invariably enters within the context of continuum elasticity .
one of the most interesting predictions of the theory is the creation of large , and roughly uniform pseudo - magnetic fields and deformation potentials under strain conformations having a three - fold symmetry @xcite ..
Please generate the next two sentences of the article | those theoretical predictions have been successfully verified experimentally @xcite .
nevertheless , different theoretical approaches to strain engineering in graphene possess subtle points and apparent discrepancies @xcite , which may hinder progress in the field . |
7,276 | Suppose that you have an abstract for a scientific paper: the behavior of microgels near surfaces and their adsorption is studied by simple scaling theory .
two different types of microgels can be studied , i.e. , fractal type microgels and randomly crosslinked polymer chains . in the first case
the gel can be described mainly by introducing a spectral dimension .
the second type requires more attention and uses the number of crosslinks as parameter .
the main result is that soft gels with weakly coupled crosslinks and a low number of crosslinks adsorb much better than hard gels , with many crosslinks .
similar results for fractal gels and branched polymer are presented .
fractal gels with low connectivity adsorb easier than gels with a large connectivity dimension .
we discuss also consequences on surface protection by microgels . .
And you have already written the first three sentences of the full article: the theory of polymers near surfaces is a very important subject for theoretical investigation .
the main reason is the very broad and deep theoretical research possible for these types of systems .
modern theories have been developed and brought to a very high standard @xcite ..
Please generate the next two sentences of the article | on the other hand there is a large demand on practical interest on studying polymers near surfaces .
one of them is surface protection . |
7,277 | Suppose that you have an abstract for a scientific paper: the scalar field can behave like a fluid with equation of state @xmath0 , where @xmath1 $ ] . in this letter
we derive a class of the scalar field potentials for which @xmath2 const .
scalar field with such a potential can mimic ordinary matter , radiation , cosmic strings , etc .
we perform our calculations in the framework of the loop cosmology with holonomy corrections .
we solve the model analytically for the whole parameter space .
subsequently , we perform similar consideration for the model with a phantom field ( @xmath3 ) . we show that scalar field is monotonic function in both cases .
this indicates that it can be treated as a well - defined internal time for these models .
moreover we perform preliminary studies of the scalar field perturbations with this potential .
we indicate that non - gaussian features are present admitting for the possible observational constraints of the model . .
And you have already written the first three sentences of the full article: in the framework of loop quantum cosmology ( lqc)@xcite one can introduce phenomenological hamiltonian @xcite @xmath4 ^ 2 \nonumber \\ & + & \frac{1}{2 } \frac { \pi_{\phi}^2 } { { |p|}^{3/2 } } + { |p|}^{3/2}v(\phi ) . \label{model}\end{aligned}\ ] ] here effects of the quantum holonomies have been introduced .
the classical limit corresponds to the case @xmath5 , what gives @xmath6 .
the parameter @xmath7 is in general function of the canonical variable @xmath8 . in our considerations.
Please generate the next two sentences of the article | we choose @xmath9 where @xmath10 .
it was shown that this leads to the proper classical limit and can be treated as a unique choice in the loop quantization class @xcite . |
7,278 | Suppose that you have an abstract for a scientific paper: as the expressive depth of an emotional face differs with individuals , expressions , or situations , recognizing an expression using a single facial image at a moment is difficult .
one of the approaches to alleviate this difficulty is using a video - based method that utilizes multiple frames to extract temporal information between facial expression images . in this paper
, we attempt to utilize a generative image that is estimated based on a given single image . then , we propose to utilize a contrastive representation that explains an expression difference for discriminative purposes .
the contrastive representation is calculated at the embedding layer of a deep network by comparing a single given image with a reference sample generated by a deep encoder - decoder network .
consequently , we deploy deep neural networks that embed a combination of a generative model , a contrastive model , and a discriminative model . in our proposed networks ,
we attempt to disentangle a facial expressive factor in two steps including learning of a reference generator network and learning of a contrastive encoder network .
we conducted extensive experiments on three publicly available face expression databases ( ck+ , mmi , and oulu - casia ) that have been widely adopted in the recent literatures .
the proposed method outperforms the known state - of - the art methods in terms of the recognition accuracy . .
And you have already written the first three sentences of the full article: facial expressions are a primary modality to understand the emotional status of an individual .
the expression provides a useful contextual clue for social communication @xcite .
however , individuals do not always clearly reveal their facial expressions ..
Please generate the next two sentences of the article | when an individual reveals an ambiguous facial expression , a human may have an experience to compare his / her expression with other expressions observed in past in order to extract their facial expression differences .
the related evidence is found in the literature of brain sciences . according to @xcite , an individual can discern various facial expressions by recalling the memorized face shapes of a shown person . |
7,279 | Suppose that you have an abstract for a scientific paper: we study the stability of a multicomponent exciton - polariton fluid under resonant excitation within the linear response approximation of a generalized gross - pitaevskii equation .
we show that , two spatially homogeneous and independently tunable pumping lasers produce , for the same values of the system parameters , up to three stable solutions .
three - stability is understood by noting that the cavity can be either little or highly populated and , in this second case , the largest part of the population lies in either one of the two components .
moreover , we discuss the different kinds of instabilities appearing at different pumps intensities and compare them with the case of one - component fluids . finally , we show that easily tunable multistable hysteresis loops can be performed by the system . .
And you have already written the first three sentences of the full article: condensates of resonantly pumped exciton - polaritons in semiconductor microcavities constitute a novel and exciting system for the study of fundamental physical properties of superfluids out of equilibrium @xcite , and for future device applications @xcite . being quantum superpositions of light and matter they are privileged candidates for the realization of the next generation of optical devices @xcite , for example for quantum information technologies . from the point of view of the fundamental physical properties ,
particularly interesting is the case of a coherently pumped polariton superfluid in presence of defects . here , in contrast to the corresponding equilibrium case , a weak residual drag force is always present even at extremely high polariton densities @xcite .
nevertheless , properties paradigmatical of an equilibrium superfluids , such as frictionless flow of polariton bullets @xcite , quantized vortices and metastable persistent flow @xcite , and the appearance and disappearance of cerenkov - like waves @xcite have been recently observed in coherently driven exciton - polaritons . in view of the potential device applications ,.
Please generate the next two sentences of the article | especially important is the unique versatility of the polaritonic system , which , combined with its high non - linear properties , have been already demonstrated to produce parametric scattering @xcite and bistability @xcite . here
, the implementation of logic operations and gates comes in a natural way : by manipulating the non - linear properties of the system using several lasers which frequencies , angles of incidence , and intensities can be freely varied externally . in this paper |
7,280 | Suppose that you have an abstract for a scientific paper: el soufi - ilias theorem establishes a connection between minimal submanifolds of spheres and extremal metrics for eigenvalues of the laplace - beltrami operator .
recently , this connection was used to provide several explicit examples of extremal metrics .
we investigate the maximality of these metrics and prove that all of them are not maximal .
+ _ 2010 mathematics subject classification .
_ 58e11 , 58j50 , 35p15 .
+ _ key words and phrases . _
extremal metric , otsuki tori , lawson tau - surfaces , bipolar surface . .
And you have already written the first three sentences of the full article: let @xmath0 be a closed surface and @xmath1 be a riemannian metric on @xmath0 .
then the laplace - beltrami operator @xmath2 acts on the space of smooth functions on @xmath0 by the formula @xmath3 it is known that the spectrum of @xmath2 is discrete and consists only of eigenvalues .
moreover , the multiplicity of any eigenvalue is finite and the sequence of eigenvalues tends to infinity ..
Please generate the next two sentences of the article | let us denote this sequence by @xmath4 where the eigenvalues are written with their multiplicities . for a fixed @xmath0 the following quantities can be considered as functionals on the space of all riemannian metrics on @xmath0 , @xmath5 several recent papers @xcite deal with finding supremum of these functionals in the space of all riemannian metrics on @xmath0 .
an upper bound for @xmath6 in terms of genus of @xmath0 was provided in the paper @xcite and the existence of such a bound for @xmath7 was shown in the paper @xcite . |
7,281 | Suppose that you have an abstract for a scientific paper: in object tracking , outlier is one of primary factors which degrade performance of image - based tracking algorithms . in this respect , therefore , most of the existing methods simply discard detected outliers and pay little or no attention to employing them as an important source of information for motion estimation .
we consider outliers as important as inliers for object tracking and propose a motion estimation algorithm based on concurrent tracking of inliers and outliers .
our tracker makes use of pyramidal implementation of the lucas - kanade tracker to estimate motion flows of inliers and outliers and final target motion is estimated robustly based on both of these information .
experimental results from challenging benchmark video sequences confirm enhanced tracking performance , showing highly stable target tracking under severe occlusion compared with state - of - the - art algorithms .
the proposed algorithm runs at more than 100 frames per second even without using a hardware accelerator , which makes the proposed method more practical and portable . .
And you have already written the first three sentences of the full article: object tracking plays a crucial role for successful implementation of various kinds of vision applications such as surveillance , human robot interaction , activity recognition , navigation of intelligent vehicles , and the like . to ensure robust performance
, object tracking almost always struggles against dynamic natural scenes .
one of the toughest challenges confronted by any tracking algorithm is to locate a target robustly in the presence of outliers resulting from partial occlusion or background clutter ..
Please generate the next two sentences of the article | an outlier can be defined as a statistical observation different in any physical value ( for example , color , shape , position , motion vector , and so on ) from the others belonging to a target in question .
outliers make it hard not only to locate a target but also to update its object model correctly . in the object tracking domain , there are roughly two different approaches to deal with outliers . |
7,282 | Suppose that you have an abstract for a scientific paper: recently , in @xcite qcd sum rules for chiral partners in the open - charm meson sector have been presented at nonzero baryon net density or temperature up to and including mass dimension 5 . referring to this ,
details concerning the cancellation of infrared divergences are presented and important technical and conceptional ingredients for an incorporation of four - quark condensates beyond factorization and of other mass dimension 6 condensates are collected . .
And you have already written the first three sentences of the full article: a natural way to investigate dynamical chiral symmetry breaking is via considering the spectral difference of chiral partners . in @xcite , chiral partner sum rules for heavy - light quark mesons in the spin 0 and spin 1 channels
have been presented . for heavy - light quark mesons ,
a crucial step in the evaluation of the operator product expansion is the cancellation of infrared divergences in virtue of the introduction of non - normal ordered condensates ..
Please generate the next two sentences of the article | thereby , the absorption of infrared divergent wilson coefficients into the condensates at non - zero densities or temperatures requires additional renormalization relations . in @xcite , in - medium relations which are consistent to the vacuum case have been given .
however , only the pseudoscalar case has been investigated there and , moreover , a general proof to all orders in the mass dimension is still missing . |
7,283 | Suppose that you have an abstract for a scientific paper: long - range magnetostatic interaction between wires strongly depends on their spatial position .
this interaction , combined with applied tensile stress , influences the hysteresis loop of the system of wires through the stress dependence of their coercive fields . as a result
, we obtain a set of stable magnetic states of the system , dependent on the applied field , applied stress and mutual positions of the wires .
these states can be used to encode the system history .
* stable states of systems of bistable magnetostrictive wires against applied field , applied stress and spatial geometry * + p. gawroski@xmath0 , a. chizhik@xmath1 , j. m. blanco@xmath2 and k. kuakowski@xmath3 + _ @xmath4 faculty of physics and applied computer science , agh university of science and technology , al .
mickiewicza 30 , 30 - 059 krakw , poland + @xmath5 departamento fisica de materiales , facultad de quimica , upv , 1072 , 20080 san sebastian , spain + @xmath2 departamento fisica aplicada i , eupds , upv / ehu , plaza europa , 1 , 20018 san sebastian , spain + @xmath6e - mail : [email protected] + @xmath7e - mail : [email protected] + @xmath8e - mail : [email protected] + _ _ pacs numbers : _
75.50.kj , 75.60.ej , 75.80.+q _ keywords : _ micromagnetism , amorphous wires , hysteresis , magnetostatics .
And you have already written the first three sentences of the full article: amorphous magnetic wires are of interest for their actual and potential use , e. g. in sensors @xcite . as it is almost usual in micromagnetism , their properties depend on the technique of sample preparation and thermal treatment . then , they are a good subject for computational science . the problem of the stray field and/or magnetization distribution of the wire have been treated either by means of a purely computational methods , where the wire volume is divided into magnetically polarized units @xcite , or within the dipolar or similar model approximation @xcite .
the latter approach is particularly suitable for magnetic arrays , formed as sets of parallel microwires perpendicular to the array @xcite .
other authors used an approximation of a homogeneous interaction field @xcite . as it was pointed out by velazquez et al ..
Please generate the next two sentences of the article | @xcite , the homogeneous field does not work for short interwire distances .
moreover , in fact the spatial distribution of the magnetization near the wire ends remains unknown ; and it is precisely in this area where the remagnetization process starts . as a consequence , our knowledge on the subtle process of the switching of the magnetic moment in the wire advances with difficulties , despite an obvious interest motivated by technology . |
7,284 | Suppose that you have an abstract for a scientific paper: we investigate a commonly used formula which seems to give non - integral vacuum charge in the continuum limit .
we show that the limit is subtle and care must be taken to get correct results . .
And you have already written the first three sentences of the full article: in this note we consider the continuum limit of a field theory defined in a large box of size @xmath0 . in the limit @xmath1 , all discrete states apart from bound states become continuum states . according to most textbooks , quantum field theory
is supposed to be well understood in this limit .
we show , however , that the limiting procedure is subtle and unless proper care is exercized the usual prescriptions may give incorrect results . in particular ,.
Please generate the next two sentences of the article | we show an example where the charge of the system seems to be a continuous function of the background field whereas it should be integer - valued .
an example which we have discussed in previous papers ( which are referred to as cdi @xcite and cd2 @xcite ) is provided by the second quantized dirac theory in the presence of a one dimensional four - vector potential vanishing at spatial infinity . the usual limiting procedure for counting states in the continuum limit |
7,285 | Suppose that you have an abstract for a scientific paper: we present results of deep echelle spectrophotometry of eight galactic regions located at galactocentric distances between 6.3 and 10.4 kpc .
the data have been taken with the very large telescope ( vlt ) ultraviolet echelle spectrograph ( uves ) in the 3100 to 10360 range .
we have derived c@xmath0 and o@xmath0 abundances from recombination lines for all the objects , as well as o@xmath1 abundances from this kind of lines for three of the nebulae .
the intensity of recombination lines is almost independent on the assumed electron temperature as well as on the possible presence of spatial temperature variations or fluctuations inside the nebulae .
these data allow the determination of the gas - phase c and o abundance gradients of the galactic disk , of paramount importance for chemical evolution models .
this is the first time the c gradient is derived from a so large number of regions and for a so wide range of galactocentric distances .
abundance gradients are found of the form @xmath2log(o / h ) = @[email protected] dex kpc@xmath5 , @xmath2log(c / h ) = @[email protected] dex kpc@xmath5 , and @xmath2log(c / o ) = @[email protected] dex kpc@xmath5 . .
And you have already written the first three sentences of the full article: the analysis of intensity ratios of collisionally excited lines ( cels ) is the standard method for deriving ionic abundances in ionized nebulae .
almost all the available determinations of the gas - phase galactic abundance gradients from regions observations are based on this kind of analysis @xcite .
the use of cels has the disadvantage that their intensity strongly depends on the assumed electron temperature and on the presence of temperature variations or fluctuations over the observed volume of the nebula ..
Please generate the next two sentences of the article | the most dramatic effect of temperature fluctuations is that ionic abundances are underestimated if these fluctuations are present in the objects but not considered in the abundance calculations @xcite .
recombination lines ( rls ) of heavy element ions are very faint and have been difficult to observe in nebular spectra . |
7,286 | Suppose that you have an abstract for a scientific paper: rydberg states of atoms are of great current interest for quantum manipulation of mesoscopic samples of atoms .
long - range rydberg - rydberg interactions can inhibit multiple excitations of atoms under the appropriate conditions .
these interactions are strongest when resonant collisional processes give rise to long - range @xmath0 interactions .
we show in this paper that even under resonant conditions @xmath1 often vanishes so that care is required to realize full dipole blockade in micron - sized atom samples . .
And you have already written the first three sentences of the full article: rydberg - rydberg interactions are very interesting for use in mesoscopic quantum manipulations .
the extremely strong interactions between two rydberg atoms have been proposed to entangle large numbers of atoms in a non - trivial manner using the phenomenon of blockade @xcite . when a mesoscopic sample is illuminated with narrowband lasers tuned to a rydberg state
, only one atom at a time can be excited if the rydberg - rydberg interaction exceeds the linewidth of the laser - atom coupling ..
Please generate the next two sentences of the article | therefore the mesoscopic cloud of atoms behaves as an effective 2-level system , with the upper level being a single collective excitation . in order to attain the strongest possible rydberg blockade , it is desirable to operate under conditions where the rydberg - rydberg interaction is not the usual @xmath2 or @xmath3 van - der - waals interactions , but instead is resonantly enhanced by `` fster @xmath4 '' processes @xcite such as @xmath5 that lead to isotropic @xmath0 long - range behavior when the @xmath6 states are degenerate with the @xmath7 states .
dramatic enhancements of collisional interactions due to such resonant couplings have been demonstrated for rydberg excitation in a magneto - optical trap@xcite . |
7,287 | Suppose that you have an abstract for a scientific paper: suppose @xmath0 is a prime power and @xmath1 $ ] is a univariate polynomial with exactly @xmath2 monomial terms and degree @xmath3 . to establish a finite field analogue of descartes rule , bi , cheng , and rojas ( 2013 ) proved an upper bound of @xmath4 on the number of cosets in @xmath5 needed to cover the roots of @xmath6 in @xmath5 . here , we give explicit @xmath6 with root structure approaching this bound : for @xmath0 a @xmath7-st power of a prime we give an explicit @xmath2-nomial vanishing on @xmath8 distinct cosets of @xmath5 .
over prime fields @xmath9 , computational data we provide suggests that it is harder to construct explicit sparse polynomials with many roots .
nevertheless , assuming the generalized riemann hypothesis , we find explicit trinomials having @xmath10 distinct roots in @xmath9 . .
And you have already written the first three sentences of the full article: how can one best bound the complexity of an algebraic set in terms of the complexity of its defining polynomials ? over the complex numbers ( or any algebraically closed field ) , bzout s theorem @xcite bounds the number of roots , for a system of multivariate polynomials , in terms of the degrees of the polynomials . over finite fields ,
weil s famous mid-20@xmath11 century result @xcite bounds the number of points on a curve in terms of the genus of the curve ( which can also be bounded in terms of degree ) .
these bounds are optimal for dense polynomials.
Please generate the next two sentences of the article | . for sparse polynomials , over fields that are not algebraically closed , these bounds can be much larger than necessary .
for example , descartes rule @xcite tells us that a univariate real polynomial with exactly @xmath2 monomial terms always has less than @xmath12 real roots , even though the terms may have arbitrarily large degree . |
7,288 | Suppose that you have an abstract for a scientific paper: based on green s function formalism , the existence of multiple mobility edges in a one - dimensional magnetic - non - magnetic superlattice geometry in presence of external electric field is predicted , and , it leads to the possibility of getting a metal - insulator transition at multiple values of fermi energy .
the role of electric field on electron localization is discussed for different arrangements of magnetic and non - magnetic atomic sites in the chain .
we also analyze that the model quantum system can be used as a perfect spin filter for a wide range of energy . .
And you have already written the first three sentences of the full article: quantum transport in low - dimensional systems has been a topic of interest within the past few decades due to its potential applicability in the field of nanoscience and nanotechnology .
exploitation of the spin degree of freedom adds a possibility of integrating memory and logic into a single device , leading to remarkable development in the fields on magnetic data storage application , device processing technique , quantum computation @xcite , etc .
naturally a lot of attention has been paid to study spin transport in low - dimensional systems both from experimental @xcite and theoretical @xcite points of view ..
Please generate the next two sentences of the article | the understanding of electronic localization in low - dimensional model quantum systems is always an interesting issue .
whereas , it is a well established fact that in an infinite one - dimensional ( @xmath0d ) system with random site potentials all energy eigenstates are exponentially localized irrespective of the strength of randomness due to anderson localization @xcite , there exists another kind of localization , known as wannier - stark localization , which results from a static bias applied to a regular @xmath0d lattice , even in absence of any disorder @xcite . till date a large number of works have been done to explore the understanding of anderson localization and scaling hypothesis in one- and two - dimensional systems @xcite . |
7,289 | Suppose that you have an abstract for a scientific paper: in this paper , we introduce an optical analogy to quantum fourier tanformation based on a pseudorandom phase ensemble .
the optical analogy also brings about exponential speedup over classical fourier tanformation . using the analogy ,
we demonstrate three classcial fields to realize fourier transform similar to three quantum particles . .
And you have already written the first three sentences of the full article: quantum fourier transform is the most important tool of quantum computation @xcite , and one of the algorithms which can bring about exponential speedup .
shor s algorithm , hidden subgroup problem and solving systems of linear equations all make use of quantum fourier transform @xcite .
quantum fourier transform utilizes the superposition of quantum state , whereby the required time and space for computation can be notably reduced from @xmath0 to @xmath1 ..
Please generate the next two sentences of the article | hence , the implementation of quantum fourier algorithm is crucial to exponential speedup in quantum computation williams , deutsch .
a novel method to simulate quantum entanglement using classical fields modulated with pseudorandom phase sequences was introduced in ref . |
7,290 | Suppose that you have an abstract for a scientific paper: we present a formulation of the interaction between a given source field and a scalar huygens metasurface ( hms ) , a recently introduced promising concept for wavefront manipulation based on a sheet of orthogonal electric and magnetic dipoles . utilizing the equivalent surface impedance representation of these metasurfaces , we establish that an arbitrary source field can be converted into directive radiation via a passive lossless hms if two physical conditions are met : local power conservation and local impedance . expressing the fields via their plane - wave spectrum and harnessing the slowly - varying approximation
we obtain semi - analytical formulae for the scattered fields , and prescribe the surface reactance required for the metasurface implementation .
the resultant design procedure indicates that the local impedance induces a fresnel - like reflection , while local power conservation forms a radiating virtual aperture which follows the total excitation field magnitude .
the semi - analytical predictions are verified by finite - element simulations of hmss designed for different source configurations . besides serving as a flexible design procedure for hms radiators
, the proposed formulation also provides a mechanism to incorporate a variety of source configurations into general hms models , as well as physical insight on the conditions enabling purely reactive implementation of this novel type of metasurfaces .
epstein and eleftheriades : passive lossless huygens metasurfaces for directive radiation metasurfaces , huygens sources , wavefront manipulation , plane - wave spectrum . .
And you have already written the first three sentences of the full article: thin sheets with repetitive metallic inclusions or exclusions have been used extensively in the past in antenna applications to control the properties of reflected or transmitted power , e.g. its direction , phase , or polarization @xcite .
such surfaces have received increasing attention lately , as part of the intensive research in the field of optical and microwave metamaterials , in an attempt to harness ideas from bulk metamterial explorations to design low - profile components with extraordinary wavefront manipulation capabilities @xcite .
in contrast to bulk metamaterials , where subwavelength elements are combined to form a volumetric entity with prescribed local response to electromagnetic fields , in metamaterial sheets , or metasurfaces , these subwavelength atomic units are confined to a region with subwavelength thickness ..
Please generate the next two sentences of the article | this geometrical difference should decrease significantly fabrication complexity of metasurfaces and also loss - related problems ; however , it requires development of new design methodologies , as the interaction of electromagnetic fields with metasurfaces is naturally described via effective boundary conditions @xcite , as opposed to effective permeabilities and permittivities ( or effective wave equations ) , more suitable for modelling volumetric metamaterials @xcite . in particular , it was recently recognized that as metasurfaces act as sources of tangential field discontinuities , they can be modelled by a distribution of electric and magnetic surface currents , prescribed by the equivalence principle [ , pp .
575 - 579 ] . |
7,291 | Suppose that you have an abstract for a scientific paper: electroosmotic pumping of fluid through a nanopore that traverses an insulating membrane is considered .
the density of surface charge on the membrane is assumed uniform , and sufficiently low for the poisson - boltzmann equation to be linearized .
the reciprocal theorem gives the flow rate generated by an applied weak electric field , expressed as an integral over the fluid volume . for a circular hole in a membrane of zero thickness , an analytical result is possible up to quadrature . for a membrane of arbitrary thickness , the full poisson
nernst planck stokes system of equations is solved numerically using a finite volume method .
the numerical solution agrees with the standard analytical result for electro - osmotic flux through a long cylindrical pore when the membrane thickness is large compared to the hole diameter .
when the membrane thickness is small , the flow rate agrees with that calculated using the reciprocal theorem . .
And you have already written the first three sentences of the full article: a nanopore is simply a hole of small size in an impermeable membrane separating two regions containing an electrolytic buffer .
a size range of 1100 nm is fairly typical .
living cells and intracellular organelles are usually bounded by lipid membranes containing nanopores constructed of membrane - bound proteins ..
Please generate the next two sentences of the article | the transport of small molecules and polymers across such nanopores is a very common feature in living cells and is essential to their normal function @xcite .
synthetic nanopores @xcite have been the focus of much interest in recent years following the demonstration of their use as effective single molecule sensors @xcite . |
7,292 | Suppose that you have an abstract for a scientific paper: an effective hadronic lagrangian consistent with the symmetries of quantum chromodynamics and intended for applications to finite - density systems is constructed .
the degrees of freedom are ( valence ) nucleons , pions , and the low - lying non - goldstone bosons , which account for the intermediate - range nucleon nucleon interactions and conveniently describe the nonvanishing expectation values of nucleon bilinears .
chiral symmetry is realized nonlinearly , with a light scalar meson included as a chiral singlet to describe the mid - range nucleon
nucleon attraction .
the low - energy electromagnetic structure of the nucleon is described within the theory using vector - meson dominance , so that external form factors are not needed .
the effective lagrangian is expanded in powers of the fields and their derivatives , with the terms organized using georgi s `` naive dimensional analysis '' .
results are presented for finite nuclei and nuclear matter at one - baryon - loop order , using the single - nucleon structure determined within the model .
parameters obtained from fits to nuclear properties show that naive dimensional analysis is a useful principle and that a truncation of the effective lagrangian at the first few powers of the fields and their derivatives is justified . .
And you have already written the first three sentences of the full article: quantum chromodynamics ( qcd ) is generally accepted as the underlying theory of the strong interaction . at low energies relevant to nuclear physics ,
however , nucleons and mesons are convenient and efficient degrees of freedom . in particular ,
relativistic field theories of hadrons , called quantum hadrodynamics ( qhd ) , have been quite successful in describing the bulk and single - particle properties of nuclei and nuclear matter in the mean - field and dirac brueckner hartree fock approximations@xcite ..
Please generate the next two sentences of the article | qhd studies based on renormalizable models , however , have encountered difficulties due to large effects from loop integrals that incorporate the dynamics of the quantum vacuum@xcite . on the other hand ,
the `` modern '' approach to renormalization @xcite , which makes sense of effective , `` cutoff '' theories with low - energy , composite degrees of freedom , provides an alternative . |
7,293 | Suppose that you have an abstract for a scientific paper: take @xmath0 to be an exponential structure and @xmath1 to be the number of minimal elements of @xmath2 where @xmath3 .
then a sequence of numbers @xmath4 is defined by the equation @xmath5 let @xmath6 denote the poset @xmath2 with a @xmath7 adjoined and let @xmath8 denote the unique maximal element in the poset @xmath2 .
furthermore , let @xmath9 be the mbius function on the poset @xmath6 .
stanley proved that @xmath10 .
this implies that the numbers @xmath11 are integers . in this paper
, we study the cases @xmath12 and @xmath13 where @xmath14 and @xmath15 are posets , respectively , of set partitions of @xmath16 $ ] whose block sizes are divisible by @xmath17 and of @xmath17-partitions of @xmath18 $ ] . in both cases
we prove that @xmath19 and @xmath20 enumerate the pyramids by applying the cartier - foata monoid identity and further prove that @xmath19 is the generalized euler number @xmath21 and that @xmath22 is the number of complete non - ambiguous trees of size @xmath23 by bijections .
this gives a new proof of welker s theorem that @xmath24 and implies the construction of @xmath17-dimensional complete non - ambiguous trees . as a bonus of applying the theory of heaps , we establish a bijection between the set of complete non - ambiguous forests and the set of pairs of permutations with no common rise .
this answers an open question raised by aval _
et al._. corresponding author email : [email protected] ; [email protected] . the author is supported by the german research foundation dfg , ji 207/1 - 1 and the austrian research fund fwf , project sfb f50 algorithmic and enumerative combinatorics . ] .
And you have already written the first three sentences of the full article: we denote by @xmath25 the poset of all the set partitions of @xmath18 $ ] ordered by refinement , that is , define @xmath26 if every block of @xmath27 is contained in a block of @xmath28 .
let @xmath29 be the minimal element of @xmath25 , i.e. , @xmath30 .
consider an interval @xmath31 $ ] in the poset @xmath25 and suppose @xmath32 and @xmath33 is partitioned into @xmath34 blocks in @xmath27.
Please generate the next two sentences of the article | . then we have @xmath31\cong\pi_{\lambda_1}\times\pi_{\lambda_2}\times\cdots\times \pi_{\lambda_k}$ ] . for the particular case @xmath35
, we have @xmath36\cong\pi_{\vert b_1\vert}\times\pi_{\vert b_2\vert}\times\cdots\times \pi_{\vert b_k\vert}$ ] . |
7,294 | Suppose that you have an abstract for a scientific paper: a neutron star low - mass x - ray binary is a binary stellar system with a neutron star and a low - mass companion star rotating around each other . in this system
the neutron star accretes mass from the companion , and as this matter falls into the deep potential well of the neutron star , the gravitational potential energy is released primarily in the x - ray wavelengths .
such a source was first discovered in x - rays in 1962 , and this discovery formally gave birth to the x - ray astronomy " . in the subsequent decades
, our knowledge of these sources has increased enormously by the observations with several x - ray space missions . here
we give a brief overview of our current understanding of the x - ray observational aspects of these systems . .
And you have already written the first three sentences of the full article: cosmic objects emit in diverse electromagnetic wavelengths from radio to @xmath0-rays . some of them ( e.g. , stars ) are luminous primarily in a narrow wavelength range , while others ( e.g. , active galactic nuclei ) emit in a broad energy spectrum .
it is , therefore , essential to observe a celestial source in various wavelengths in order to fully understand its nature . up to the middle of the twentieth century ,
visible light was the primary window for observation ..
Please generate the next two sentences of the article | but in the last few decades , wavelength - based branches of astronomy have not only been developed , but also got matured . moreover
, many new types of sources have been discovered by the observations in wavelengths other than visible lights . |
7,295 | Suppose that you have an abstract for a scientific paper: we propose the two - band @xmath0-@xmath1 model to describe theoretically a diffuse regime of the spin - dependent electron transport in magnetic tunnel junctions ( mtj s ) of the form f / o / f where f s are 3@xmath1 transition metal ferromagnetic layers and o is the insulating spacer .
we aim to explain the strong interface sensitivity of the tunneling properties of mtj s and investigate the influence of electron scattering at the nonideal interfaces on the degradation of the tmr magnitude .
the generalized kubo formalism and the green s functions method were used to calculate the conductance of the system .
the vertex corrections to the conductivity were found with the use of `` ladder '' approximation combined with the coherent - potential approximation ( cpa ) that allowed to consider the case of strong electron scattering .
it is shown that the ward identity is satisfied in the framework of this approximation that provides the necessary condition for a conservation of a tunneling current .
based on the known results of ab - initio calculations of the tmr for ballistic junctions , we assume that exchange split quasi - free @xmath0-like electrons with the density of states being greater for the majority spin sub - band give the main contribution to the tmr effect .
we show that , due to interfacial inter - band scattering , the tmr can be substantially reduced even down to zero value .
this is related to the fact that delocalized quasi - free electrons can scatter into the strongly localized @xmath1 sub - band with the density of states at the fermi energy being larger for minority spins compared to majority spins .
it is also shown that spin - flip electron scattering on the surface magnons within the interface leads to a further decrease of the tmr at finite temperature . .
And you have already written the first three sentences of the full article: magnetic tunnel junctions ( mtj s ) consisting of two ferromagnetic layers separated by the insulating spacer exhibit the tunneling magnetoresistance effect ( tmr ) when they are switched by applying a magnetic field from the antiparallel to parallel alignment of magnetizations in magnetic layers .
the tmr effect was first observed by m. julliere in 1975 @xcite .
julliere found that the tunneling conductance of the trilayer structure fe / ge / co depended on the angle between magnetizations in the fe and co layers ..
Please generate the next two sentences of the article | the measured amplitude of the tmr in these experiments was 14% at 4.2k .
only 20 years later , the large values of tmr at room temperature were obtained in magnetic junctions comprising the al@xmath2o@xmath3 barrier @xcite . since that time |
7,296 | Suppose that you have an abstract for a scientific paper: a one dimensional xx spin chain of finite length coupled to reservoirs at both ends is solved exactly in terms of a matrix product state ansatz .
an explicit reprsentation of matrices of fixed dimension @xmath0 independent of the chain length is found .
expectations of all observables are evaluated , showing that all connected correlations , apart from the nearest neighbor @xmath1 , are zero . .
And you have already written the first three sentences of the full article: simplification leading to understanding of essential features of physical systems is one of the leading principles in theoretical physics .
finding simple solutions to seemingly complicated models is one of the ways to approach this goal . in quantum physics
the complexity of a system grows exponentially with the number of particles . even if an exact solution is possible representing it in a compact way is nontrivial for many - body systems ..
Please generate the next two sentences of the article | one approach to represent a given state is to express its expansion coefficients in a suitable basis in terms of product of matrices , the so - called matrix product states @xcite , used before in a wholly different context of 2d classical lattice model @xcite .
if quantum state is only weakly correlated the resulting matrices can be small . in condensed matter |
7,297 | Suppose that you have an abstract for a scientific paper: let @xmath0 be the distribution of the random series @xmath1 , where @xmath2 is a sequence of i.i.d .
random variables taking the values 0,1 with probabilities @xmath3 .
these measures are the well - known ( biased ) bernoulli convolutions .
in this paper we study the multifractal spectrum of @xmath0 for typical @xmath4 .
namely , we investigate the size of the sets @xmath5 our main results highlight the fact that for almost all , and in some cases all , @xmath4 in an appropriate range , @xmath6 is nonempty and , moreover , has positive hausdorff dimension , for many values of @xmath7 .
this happens even in parameter regions for which @xmath0 is typically absolutely continuous . .
And you have already written the first three sentences of the full article: if @xmath8 is a measure on @xmath9 ( or , more generally , on a metric space ) , the _ local dimension _ of @xmath8 at @xmath10 is defined as @xmath11 provided the limit exists .
( here , and throughout the paper , @xmath12 denotes the open ball of center @xmath10 and radius @xmath13 . ) for many natural measures @xmath8 , such as self - similar measures and measures invariant and ergodic under hyperbolic diffeomorphisms , the local dimension exists and is constant @xmath8-almost everywhere .
however , even in this case there may be many points for which the local dimension takes exceptional values ( or fails to exist ) ..
Please generate the next two sentences of the article | the multifractal analysis for local dimensions is broadly concerned with the study of the level sets @xmath14 the goal is to compute or estimate the _ dimension spectrum _ of @xmath8 , that is , the function @xmath15 where @xmath16 denotes hausdorff dimension . loosely speaking ,
a measure is termed _ multifractal _ if @xmath17 for a range of values of @xmath7 . for many natural measures , such as self - similar measures under the open set condition |
7,298 | Suppose that you have an abstract for a scientific paper: columns of @xmath0 matrices are shown to create different sets of @xmath1 operators acting on @xmath2-dimensional hilbert space .
this construction corresponds to a formalism of the star - product of operator symbols .
the known bases are shown to be partial cases of generic formulas derived by using @xmath0 matrices as a source for constructing arbitrary bases .
the known examples of the sic - povm , mubs , and the phase - space description of qubit states are considered from the viewpoint of the developed unified approach .
star - product schemes are classified with respect to associated @xmath3 matrices .
in particular , unitary matrices correspond to self - dual schemes .
such self - dual star - product schemes are shown to be determined by dequantizers which do not form povm .
[ sh ] * * [ cols="^ " , ] .
And you have already written the first three sentences of the full article: to conclude , we present the main results of the paper . a bijective map : @xmath4 operators in @xmath5 matrix @xmath6 is constructed and associated with a star - product formalism . for @xmath1 these operators to form a basis in @xmath7 , conditions on matrix @xmath8 are derived . classification of possible matrices @xmath8 and related star - product schemes @xmath9 is accomplished .
this gives rise to a new approach of introducing bases in @xmath7 with desired properties .
one chooses a class of matrices and impose additional limitations ..
Please generate the next two sentences of the article | once matrix @xmath8 is built , a corresponding basis ( set of operators ) in @xmath7 with expected properties appears .
a development of the paper is complemented by illustrating examples . |
7,299 | Suppose that you have an abstract for a scientific paper: in general , infinite switching behaviour near networks is associated with the existence of suspended horseshoes .
trajectories that realize switching lie within these transitive sets . in this note , revisiting the equivariant shilnikov scenario , we describe an attracting homoclinic network exhibiting forward switching and without suspended horseshoes in its neighbourhood .
thus we provide an example of an asymptotically stable network exhibiting sensitive dependence on initial conditions . en gnral , le comportement de commutation autour des rseaux est associ lexistence de fers cheval en suspension .
trajectoires qui ralisent la commutation se situent dans ces ensembles transitifs .
dans cette note , visitant le scnario classique de shilnikov avec une symtrie , nous dcrivons un rseau homocline qui prsente commutation nayant pas des fers cheval en suspension autour de lui .
plus prcisement nous donnons un exemple dun rseau asymptotiquement stable avec sensible dpendance des conditions initiales . .
And you have already written the first three sentences of the full article: the existence of homo and heteroclinic cycles in systems with symmetry is no longer a surprising feature .
there are several examples of cycles arising in differential equations symmetric under the action of a specific compact lie group .
several definitions of heteroclinic cycles and networks have been given in the literature ..
Please generate the next two sentences of the article | these objects are associated with intermittent dynamics and used to model stop - and - go behaviour in various applications . throughout the present article , we use the following definition valid for a finite dimensional system of ordinary equations ( ode ) : a _ heteroclinic cycle _
is a finite collection of equilibria @xmath0 of the ode together with a set of heteroclinic connections @xmath1 where @xmath2 is a solution of the ode such that : @xmath3 and @xmath4 . |
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