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7,900 | Suppose that you have an abstract for a scientific paper: in this paper , we study large - scale structures from numerical simulations , paying particular attention to supercluster - like structures .
a grid - density - contour based algorithm is adopted to locate connected groups . with the increase of the linking density threshold from the cosmic average density ,
the foam - like cosmic web is subsequently broken into individual supercluster - like groups and further halos . to be in accordance with normal fof halos with the linking length of @xmath0 in unit of the average separation of particles , halos in this paper
are defined as groups with the linking density threshold @xmath1 , where @xmath2 is the grid density , @xmath3 is the average mass density of the universe .
groups with lower linking densities are then generally referred to as supercluster - like groups . by analyzing sets of cosmological simulations with varying cosmological parameters , we find that a universal mass function exists not only for halos but also for low - density supercluster - like groups until the linking density threshold decreases to @xmath4 where the global percolation of large - scale structures occurs .
we further show that the mass functions of different groups can be well described by the jenkins form with the parameters being dependent on the linking density threshold . on the other hand
, these low - density supercluster - like groups can not be directly associated with the predictions from the excursion set theory with effective barriers obtained from dynamical collapse models , and the peak exclusion effect must be taken into account .
including such an effect , the mass function of groups with the linking density threshold @xmath5 is in good agreements with that from the excursion set theory with a nearly flat effective barrier .
a simplified analysis of the ellipsoidal collapse model indicates that the barrier for collapses along two axes to form filaments is approximately flat in scales .
thus in our analyses , we define groups identified with....
And you have already written the first three sentences of the full article: one of the key issues in cosmological studies is to understand the physical processes related to the structure formation in the universe . in the cold dark matter scenario ,
gravitational effects play essential roles in amplifying small density fluctuations generated in the early universe to shape the large - scale structures seen today .
being directly associated with galaxies and clusters of galaxies , virialized dark matter halos have been widely studied theoretically and observationally ..
Please generate the next two sentences of the article | their mass function , which describes statistically the formation and evolution of dark matter halos , is shown by numerical simulations to follow a functional form universally valid for a wide range of cosmological models ( e.g. , * ? ? ?
* ; * ? ? ? |
7,901 | Suppose that you have an abstract for a scientific paper: the mechanism of dynamical mass generation for the gauge field is studied through 1-loop .
we find out that torsion is an obstruction to the appearance of a 1-loop mass correction .
contrary , if torsion is not present , a mass gap is generated for the 2-form field . .
And you have already written the first three sentences of the full article: the abelian 2-form gauge potential , usually referred to as kalb - ramond field ( k - r ) , exhibits a number of interesting features in four dimensional space - time ( 4d ) @xcite ; special emphasis is given to the fact that it mixes up with the electromagnetic gauge potential so as to yield a massive spin-1 excitation based on a @xmath0 ^2$]-symmetry , without the need for higgs scalars @xcite .
more recently , the coupling between the k - r and maxwell fields has been reconsidered in connection with the issue of dirac - like monopoles with massive photons @xcite .
also , interesting discussions on the possible non - abelian extension of the k - r field are set in the works of ref ..
Please generate the next two sentences of the article | @xcite . reassessing the k - r field in three dimensional space - time ( 3d ) brings about some peculiarities that show up as a by - product of three dimensional space - time .
for example , the abelian gauge field dual to the k - r potential in 3d is subject to a particular gauge symmetry that selects its longitudinal component as the physical propagating mode , whereas its transverse part appears as a compensating mode , and so it can always be gauged away . |
7,902 | Suppose that you have an abstract for a scientific paper: we present a comparative study of the glass forming ability of binary systems with varying composition , where the systems have similar global crystalline structure ( cscl+fcc ) .
biased monte carlo simulations using umbrella sampling technique shows that the free energy cost to create a cscl nucleus increases as the composition of the smaller particles are decreased .
we find that the systems with comparatively lower free energy cost to form cscl nucleus exhibit more pronounced pre - crystalline demixing near the liquid / crystal interface . the structural frustration between the cscl and fcc crystal demands this demixing .
we show that closer to the equimolar mixture the entropic penalty for demixing is lower and a glass forming system may crystallize spontaneously when seeded with a nucleus .
this entropic penalty as a function of composition shows a non - monotonic behavior with a maximum at a composition similar to the well known kob - anderson ( ka ) model .
although the ka model shows the maximum entropic penalty and thus maximum frustration against cscl formation , it also shows a strong tendency towards crystallization into fcc lattice of the larger a " particles which can be explained from the study of the energetics .
thus for systems closer to the equimolar mixture although it is the requirement of demixing which provides their stability against crystallization , for ka model it is not demixing but slow dynamics and structural frustration caused by the locally favored structure around the smaller b " particles which make it a good glass former .
although the glass forming binary systems studied here are quite similar , differing only in composition , we find that their glass forming ability can not be attributed to a single phenomena . .
And you have already written the first three sentences of the full article: a liquid upon cooling undergoes first order phase transition and forms a crystal .
however if the cooling rate is increased it can not crystallize and forms an amorphous glassy material @xcite .
in addition to fast supercooling , there are other methods to favor glass formation over crystallization . in bulk metallic glass community.
Please generate the next two sentences of the article | the usual thumb rules are to at least have a two component mixture with negative enthalpy of mixing and a 12@xmath0 size ratio between the components @xcite .
single component systems are known to crystallize in a fcc+hcp structure @xcite , thus multi - component systems are commonly used for making glasses . |
7,903 | Suppose that you have an abstract for a scientific paper: we have carried out @xmath0co j=21 line observations of the supernova remnant ( snr ) hb 21 in order to search for evidence of interaction with molecular clouds .
we mapped the eastern half ( @xmath1 ) of the snr almost completely .
molecular gas appears to be distributed mainly along the boundary of the snr , but the overall distribution has little correlation either with the distortion of the snr boundary or with the distribution of radio brightness . along the eastern boundary , where the snr was considered to be interacting with molecular clouds in previous studies ,
we have not found any strong evidence for the interaction .
instead we detected broad ( 2040 ) co emission lines in the northern and southern parts of the snr .
in the northern area , the broad - line emitting cloud is composed of a small ( @xmath2 or 0.5 pc ) , very bright , u - shaped part and several clumps scattered around it . there is a significant enhancement of radio emission with flat ( @xmath3 ) spectral index possibly associated with this cloud . in the southern area ,
the broad - line emitting cloud is filamentary and appears to form an elongated loop of @xmath4 in extent .
small ( @xmath5 or 0.3 pc ) , bright clumps are seen along the filamentary structure . we have obtained sensitive j=10 and j=21 spectra of @xmath0co and @xmath6co molecules toward several peak positions .
the intensity of @xmath0co j=21 emission is low ( @xmath7 k ) and the ratio of @xmath0co j=21 to j=10 integrated intensities is high ( 1.62.3 ) , which suggests that the emission is from warm , dense , and clumpy gas .
we have applied an lvg analysis to derive their physical parameters .
the detected broad co lines are believed to be emitted from the fast - moving molecular gas swept - up by the snr shock . the small ( @xmath8 ) shock velocity suggests that the shock is a non - dissociating c - shock .
we discuss the correlation of the shocked molecular gas with the previously detected , shocked atomic gas and the associated....
And you have already written the first three sentences of the full article: the number of supernova remnants ( snrs ) with convincing evidence for interaction with ambient molecular clouds has increased considerably in recent years .
the evidence ranges from a simple morphological relation to the detection of broad and/or shock - excited emission lines from various molecules .
although circumstantial evidence could be very suggestive , it is the molecular lines from the shocked gas that are essential for understanding the physical and chemical processes associated with the molecular shock . in this regard , there are still only a few snrs adequate for the study of molecular cloud - shock interaction ; perhaps w28 ( arikawa et al . 1999 ) , w44 ( seta et al ..
Please generate the next two sentences of the article | 1998 ) , w51c ( koo & moon 1997 ) , 3c391 ( reach & rho 1996 , 1999 ) , and the classical source ic 443 ( denoyer 1979 ; tauber et al . 1994 and references therein ) . in this paper , we report the discovery of broad emission lines from the shocked co gas in hb 21 .
hb 21 ( g89.0 + 4.7 ) is one of those snrs with mixed morphology , e.g. , shell - like in radio and center - filled in the x - ray ( rho & petre 1998 ) , where the center - filled , thermal x - ray emission is suggested to be due to interaction with molecular clouds . |
7,904 | Suppose that you have an abstract for a scientific paper: we show that the space called shark teeth is a topological ifs - attractor , that is for every open cover of @xmath0 , its image under every suitable large composition from the family of continuous functions @xmath1 lies in some set from the cover . in particular , there exists a space which is not homeomorphic to any ifs - attractor but is a topological ifs - attractor .
iterated function systems ( ifs ) are one of the most popular and simple method of constructing fractal structures , which has wide applications to data compression , computer graphics , medicine , economics , earthquake and weather prediction and many others .
a compact metric space @xmath2 is called an _ ifs - attractor _ if @xmath0 for some contractions @xmath3 . in this case
the family @xmath4 is called an _ iterated function system_. we recall that a map @xmath5 is a _ contraction _ if its lipschitz constant @xmath6 is less than 1 . the notion of an iterated function system
was introduced by john hutchinson in 1981 @xcite and popularized by michael barnsley @xcite .
topological properties of ifs - attractors were studied in @xcite , @xcite and @xcite .
in particular the definition of topological ifs - attractor was proposed in the last paper : compact topological space @xmath2 is a _
topological ifs - attractor _
if @xmath0 for some continuous maps @xmath3 with the property that for any open cover @xmath7 of @xmath2 there is @xmath8 , such that for any functions @xmath9 the set @xmath10 lies in some set @xmath11 .
note that every compact , metric space @xmath2 is a topological ifs - attractor if for its any open cover @xmath7 the diameter of the set @xmath10 is less than the lebesgue number of @xmath7 , for some @xmath8 and every @xmath9 .
it is easy to see that each ifs - attractor is a topological ifs - attractor but not the other way around .
moreover , we show that a space called shark teeth , constructed in @xcite , which is not homeomorphic to attractor of any iterated function system is a....
And you have already written the first three sentences of the full article: consider the piecewise linear periodic function @xmath12 \text { for some } n\in{\mathbb z } , \\ n - t & \text{if } t\in[n-\frac{1}{2},n ] \text { for some } n\in{\mathbb z } , \end{cases}\ ] ] whose graph looks as follows ( 300,80)(-30,-10 ) ( -20,0)(1,0)300 ( 275,-10)@xmath13 ( 0,-10)(0,1)70 ( -20,20)(1,-1)20 ( 0,0)(1,1)40 ( 40,40)(1,-1)40 ( 80,0)(1,1)40 ( 120,40)(1,-1)40 ( 160,0)(1,1)40 ( 200,40)(1,-1)40 ( 240,0)(1,1)20 for every @xmath14 consider the function @xmath15 which is a homothetic copy of the function @xmath16 .
spaces called _ shark teeth _ are constructed in @xcite and are parametrized by an infinite non - decreasing sequence @xmath17 .
let @xmath18\times\{0\}$ ] be the _.
Please generate the next two sentences of the article | bone _ of shark teeth , and for every @xmath19 let @xmath20\big\}$ ] be the @xmath21th _ row _ of teeth .
the space shark teeth is given by the following formula @xmath22 in @xcite is shown that the shark teeth constructed in the plane @xmath23 with the non - decreasing sequence @xmath24 where @xmath25 is the integer part of @xmath26 , is not homeomorphic to an ifs - attractor ( see figure [ shark ] ) . |
7,905 | Suppose that you have an abstract for a scientific paper: the temporal decay of mass accretion in young stars is a fundamental tracer of the early evolution of circumstellar disks . through population syntheses ,
we study how correlated uncertainties between the estimated parameters of young stars ( luminosity , temperature , mass , age ) and mass accretion rates @xmath0 , as well as observational selection effects , can bias the temporal decay of mass accretion rates ( @xmath1 ) inferred from a comparison of measured @xmath0 with isochronal ages in young stellar clusters . we find that the presence of realistic uncertainties reduces the measured value of @xmath2 by up to a factor of 3 , leading to the inference of shallower decays than the true value .
this suggests a much faster temporal decay of @xmath0 than generally assumed . when considering the minimum uncertainties in ages affecting the orion nebula cluster , the observed value @xmath3 , typical of galactic star forming regions , can only be reproduced if the real decay exponent is @xmath4 .
this effect becomes more severe if one assumes that observational uncertainties are larger , as required by some fast star formation scenarios .
our analysis shows that while selection effects due to sample incompleteness do bias @xmath2 , they can not alter this main result and strengthen it in many cases .
a remaining uncertainty in our work is that it applies to the most commonly used and simple relationship between @xmath0 , the accretion luminosity and the stellar parameters .
we briefly explore how a more complex interplay between these quantities might change the results .
[ firstpage ] stars : formation , pre - main - sequence , variables : t - tauri , fundamental parameters , circumstellar matter ; hertzsprung - russell and colour - magnitude diagrams .
And you have already written the first three sentences of the full article: accretion of material from the circumstellar disk onto the central star is a common process occurring during the pre - main sequence ( pms ) phase of stellar evolution @xcite .
disk accretion is responsible for the build up of a significant fraction of the final stellar mass , thus affecting in part the shape of the initial mass function ( imf ) .
on - going accretion is also direct evidence of the presence of gaseous circumstellar disc material close to the star and therefore the time dependence of the mass accretion rate ( @xmath5 ) traces disc evolution ..
Please generate the next two sentences of the article | moreover , accretion influences the disk structure and thus contributes to the conditions for planet formation .
understanding the temporal evolution of mass accretion rates is crucial for modelling both planet formation and the early evolution of stars . |
7,906 | Suppose that you have an abstract for a scientific paper: we reanalyze _
fermi_/lat gamma - ray spectra of bright blazars with a higher photon statistics than in previous works and with new pass 7 data representation . in the spectra of the brightest blazar 3c 454.3 and possibly of 4c + 21.35
we detect breaks at @xmath05 gev ( in the rest frame ) associated with the photon - photon pair production absorption by lyman continuum ( lyc ) .
we also detect confident breaks at @xmath020 gev associated with hydrogen lyc both in the individual spectra and in the stacked redshift - corrected spectrum of several bright blazars .
the detected breaks in the stacked spectra univocally prove that they are associated with atomic ultraviolet emission features of the quasar broad - line region ( blr ) .
the dominance of the absorption by hydrogen ly complex over , rather small detected optical depth , and the break energy consistent with the head - on collisions with lyc photons imply that the gamma - ray emission site is located within the blr , but most of the blr emission comes from a flat disk - like structure producing little opacity .
alternatively , the lyc emission region size might be larger than the blr size measured from reverberation mapping , and/or the @xmath1-ray emitting region is extended .
these solutions would resolve a long - standing issue how the multi - hundred gev photons can escape from the emission zone without being absorbed by softer photons . .
And you have already written the first three sentences of the full article: the spectra of bright blazars obtained by _ fermi gamma - ray space telescope _
( _ fermi _ ) large area telescope ( lat ) showed clear deviations from a power - law shape @xcite .
there spectra could not be described by smooth functions such as exponentially cutoff power - law or a log - parabola ( log - normal distribution ) , but were found to be better described by a broken power - law ..
Please generate the next two sentences of the article | the derived break energies lying in the 110 gev energy range @xcite were rather stable @xcite .
those breaks seemed puzzling : the hypothesis that the break is caused by photon - photon annihilation through @xmath2 pair production was considered and rejected by @xcite , who argued that `` to produce a break in the 110 gev , the photon field should have an energy peaking in the 0.050.5 kev range , which excludes the broad - line region peaking in the uv . '' |
7,907 | Suppose that you have an abstract for a scientific paper: the cross section asymmetry @xmath0 has been measured for the photoproduction of @xmath1-mesons off protons , using polarized photons in the energy range @xmath2gev .
the cm angular coverage is @xmath3 with energy and angle steps of 25mev and @xmath4 , respectively .
the obtained @xmath0 data , which cover the second and third resonance regions , are compared with existing experimental data and recent phenomenological analyses .
the influence of these measurements on such analyses is also considered .
+ pacs numbers : 13.60.le , 25.20.lj + .
And you have already written the first three sentences of the full article: single - pion photoproduction has been used extensively to explore the electromagnetic properties of nucleon resonances , and most determinations of the @xmath5 resonance couplings @xcite have been obtained through multipole analyses of this reaction .
the study of @xmath6 properties , in general , has enjoyed a resurgence , driven by the growth of new facilities worldwide .
many precise new measurements have focused on the photoproduction of pions and other pseudoscalar mesons , in the hope that they would reveal states not seen previously in the photoproduction and elastic scattering of pions ..
Please generate the next two sentences of the article | associated studies have suggested both new states and couplings to existing states which contradict those found in analyses of the full pion production database .
these results demonstrate the influence of measurements sensitive to new quantities and suggest that older analyses may have been based on insufficient or flawed data sets . |
7,908 | Suppose that you have an abstract for a scientific paper: we report on x - ray observations of the core of the shapley supercluster . combining data from pointed observations of the rosat pspc detector and data from the rosat all - sky survey
, the observed region covers an area of @xmath0 .
it contains the central clusters a3562 , a3558 and a3556
. we find clear evidence for x - ray emission connecting the three clusters .
this confirms the existence of a filamentary , physical structure embedding the three clusters a3562 , a3558 and a3556 .
we also find evidence for faint emission westwards of a3556 . in total , the extension of the filamentary x - ray emission of the core of the shapley supercluster amounts up to at least @xmath1 mpc .
the total luminosity in the 0.1 - 2.4 kev energy band is @xmath2 erg s@xmath3 . .
And you have already written the first three sentences of the full article: the shapley supercluster ( ssc ) has for long been known as a large region of a high overdensity of galaxies ( shapley 1930 ) . located in in the direction of hydra - centaurus at @xmath4 it is one of the densest large scale concentrations of matter ( fabian 1991 ) in the universe .
if clusters of galaxies are taken as mass tracers ( scaramella et al . 1989 ) , the shapley concentration accounts for at least 10 - 20% of the acceleration of the local group towards the great attractor ( lynden - bell et al .
1988 , scaramella et al ..
Please generate the next two sentences of the article | 1991 , drinkwater et al .
1998 ) . |
7,909 | Suppose that you have an abstract for a scientific paper: with adaptive optics imaging at keck observatory , we have discovered a substellar companion to the f6 pleiades star hd 23514 , one of the dustiest main - sequence stars known to date ( @xmath0 ) .
this is one of the first brown dwarfs discovered as a companion to a star in the pleiades .
the 0.06 m@xmath1 late - m secondary has a projected separation of @xmath2360 au .
the scarcity of substellar companions to stellar primaries in the pleiades combined with the extremely dusty environment make this a unique system to study . .
And you have already written the first three sentences of the full article: hd 23514 ( hii 1132 ) is an f6 star in the pleiades .
it is one of only a handful of youthful stars , ages 35 to @xmath2100 myr , that are surrounded by warm dust particles located in the terrestrial planet zone and which absorb a percent or so of the bolometric luminosity of their central star @xcite .
we have observed hd 23514 with an adaptive optics system at the keck observatory using the nirc2 camera to check the binarity of this unusually dusty star . to the best of our knowledge , to date.
Please generate the next two sentences of the article | no substellar companion to a stellar primary has been found in the pleiades .
however , while this paper was being reviewed , @xcite announced the discovery of a substellar companion to the pleiad hii 1348 . |
7,910 | Suppose that you have an abstract for a scientific paper: the dissipation of turbulent gas motions is one of the likely mechanisms that has been proposed to heat the intracluster medium ( icm ) in the cores of clusters and groups of galaxies .
we consider the impact of gas motions on the width of the most prominent x - ray emission lines . for heavy elements ( like iron )
the expected linewidth is much larger than the width due to pure thermal broadening and the contribution due to turbulent gas motions should be easily detected with the new generation of x - ray micro - calorimeters , such as the spektr - rg calorimeter ( sxc ) .
for instance in the perseus cluster the turbulent velocity required to balance radiative cooling ( as derived by rebusco et al .
2006 ) , would imply a width of the 6.7 kev fe line of 10 - 20 ev , while the pure thermal broadening is @xmath04 ev . the radial dependence of the linewidth is sensitive to i ) the radial dependence of the velocity amplitude and ii ) the `` directionality '' of the stochastic motions ( e.g. isotropic turbulence or predominantly radial gas motions ) .
if the width of several lines , characteristic for different gas temperatures , can be measured , then it should be possible to probe both the `` directionality '' and the amplitude of the gas motions .
moreover a measurement of the width would put a lower limit on the amount of the kinetic energy available for dissipation , giving a constraint on the icm models .
[ firstpage ] turbulence - line : profiles - cooling flows - clusters : individual : perseus .
And you have already written the first three sentences of the full article: clusters of galaxies are the largest gravitationally bound and nearly virialized systems in the universe .
high resolution x - ray surveys have revealed that the icm ( with temperatures in the range @xmath1 kev ) is not fully relaxed .
the substructures in the surface brightness and temperature are observed both on large scales and in the cluster cores indicating that the gas is not at rest . at the same time.
Please generate the next two sentences of the article | strong shocks are rarely observed ( see markevitch & vikhlinin , 2007 for a review ) suggesting that the cluster gas motions are predominantly subsonic .
the shape of the emission lines as a source of information on the icm velocity distribution has been discussed in detail in sunyaev , norman & bryan ( 2003 ) and inogamov & sunyaev ( 2003 ) . |
7,911 | Suppose that you have an abstract for a scientific paper: in this paper we describe the pseudoparticles , holons , and spinons whose occupancy configurations describe the energy eigenstates of the one - dimensional ( 1d ) hubbard model in terms of rotated electrons . rotated electrons are related to electrons by a mere unitary transformation such that rotated electron double occupation is a good quantum number and the _ effective electronic lattice _ occupied by rotated electrons is identical to the _ real - space lattice _ occupied by electrons .
moreover , we find that the band - momentum pseudoparticle description associated with the bethe - ansatz takahasi s thermodynamic equations is related by fourier transform to a _ local pseudoparticle _ representation in terms of occupancy configurations of spatial coordinates .
such spatial coordinates correspond to an _ effective pseudoparticle lattice_. there is an effective pseudoparticle lattice for each pseudoparticle branch with finite occupancy in a given state .
this description introduces the local pseudoparticles whose spatial coordinate is the conjugate of the band momentum .
we describe the energy eigenstates in terms of local pseudoparticle site distribution configurations in such lattices .
moreover , we relate both the local pseudoparticle internal structure and the latter configurations to the rotated - electron site distribution configurations which describe the energy eigenstates .
the electron - rotated - electron unitary transformation is such that the latter configurations are independent of the value of the on - site coulombian repulsion .
our findings provide useful information about the relation of the exotic pseudoparticles , holons , and spinons that diagonalize the non - perturbative many - electron problem to the original electrons .
we provide an example showing how the derived local pseudoparticle representation can be used in the evaluation of finite - energy few - electron spectral function expressions . .
And you have already written the first three sentences of the full article: low - dimensional , correlated systems have attracted much attention in recent years due to a large variety of unconventional electronic properties directly connected with electronic correlations . in this context
one - dimensional ( 1d ) systems are of special interest , essentially stimulated by theoretical predictions like charge - spin separation for the 1d hubbard model @xcite .
while the 1d hubbard model @xcite is the prototype of an exactly solvable model for correlated electrons , such a charge - spin separation corresponds to the description of the energy eigenstates in terms of occupancy configurations of holons and spinons ..
Please generate the next two sentences of the article | recently the charge - spin separation of that model was shown to occur for all values of excitation energy , the corresponding holon and spinon description being extended to the complete set of energy eigenstates which span the hilbert space @xcite .
on the other hand , quasi-1d materials are ideal model systems which allow the study of basic physical concepts in one dimension . in the last years |
7,912 | Suppose that you have an abstract for a scientific paper: a dc voltage changed periodically with magnetic field is observed on segments of asymmetric aluminum loop without any external dc current at temperatures corresponded to superconducting transition . according to this experimental result
a segment of the loop is a dc power source .
a possibility of a persistent voltage on segments of an inhomogeneous normal metal mesoscopic loop follows from this result . .
And you have already written the first three sentences of the full article: it is known that the persistent current ( i.e. a direct current in the thermodynamic equilibrium state ) can flow along a mesoscopic loop because of the quantization of the momentum circulation @xmath0 the persistent current @xmath1 in normal metal mesoscopic loops was predicted more than 30 years ago [ 1 ] and was observed not so long ago [ 2 ] .
it is known also that a potential difference @xmath2 should be observed on a segment @xmath3 of an inhomogeneous conventional loop at a current density @xmath4 along the loop if the average resistivity along the segment @xmath5 differs from the one along the loop @xmath6 .
therefore a possibility of a persistent voltage can be assumed at a segment of an inhomogeneous mesoscopic loop at @xmath7 ..
Please generate the next two sentences of the article | the latter , i.e. @xmath7 , can be only if the mean free path of electrons is not smaller than the length @xmath8 of loop circumference and the temperature is lower than the energy difference between adjacent permitted states @xmath9 .
this difference is not large for electrons . |
7,913 | Suppose that you have an abstract for a scientific paper: theories of quantum gravity suggest the existence of a minimal length scale .
we study the consequences of a particular implementation of the idea of a minimal length scale in the model of large extra dimensions , the add model . to do this
we have looked at real graviton production in association with a jet at hadron colliders . in the minimal length scenario ,
the bounds on the effective string scale are significantly less stringent than those derived in the conventional add model , both at the upgraded tevatron and at the large hadron collider . `
pacs nos : 11.25.wx , 13.85.qk ` + ` key words : extra dimension , minimal length , hadron collider ` ` hep - ph/0512050 ` + sinp / tnp/05 - 28 + tifr / th/05 - 46 + * studying the effects of minimal length in large extra dimensional models in the jet @xmath0 missing energy channels at hadron colliders * + , kumar rao @xmath1 , k. sridhar @xmath1 + \1 .
saha institute of nuclear physics , 1/af bidhan nagar , kolkata 700064 , india + 2 .
department of theoretical physics , tata institute of fundamental research , + homi bhabha road , mumbai 400005 , india .
And you have already written the first three sentences of the full article: there are reasons to believe that at the planck scale , the scale at which gravity becomes a quantum phenomenon , the very structure of space - time may change . that this may happen is suggested even by general relativity . a quantum mechanical particle of momentum @xmath2 in the presence of a classical gravitational field ( the latter described by einstein s equations ) causes the metric @xmath3 to fluctuate .
this induces an additional uncertainty in position , given by @xmath4 , where @xmath5 is the planck length .
thus the usual quantum mechanical uncertainty relation gets modified to @xmath6 at high energies , the second term can become significant and lead to important deviations from the usual quantum mechanics ..
Please generate the next two sentences of the article | for example , in the usual quantum mechanics , @xmath7 is large at low values of momenta but can become small at high momenta which can provide higher resolution . with the modified uncertainty relation even at high momenta @xmath7 is limited in resolution because of strong curvature effects . in other words , independent of momentum , @xmath7 is always larger than a minimal length scale @xmath5 .
the appearance of the minimal length in the classical theory of gravity should tell us that it is no surprise to expect that such a conclusion becomes even more inevitable in a quantum theory of gravity . |
7,914 | Suppose that you have an abstract for a scientific paper: model - space effective interactions @xmath0 derived from free - space nucleon - nucleon interactions @xmath1 are reviewed .
we employ a double decimation approach : first we extract a low - momentum interaction @xmath2 from @xmath1 using a @xmath3-matrix equivalence decimation method
. then @xmath0 is obtained from @xmath2 by way of a folded - diagram effective interaction method . for decimation momentum @xmath4 ,
the @xmath2 interactions derived from different realistic @xmath1 models are nearly model independent , and so are the resulting shell - model effective interactions . for nucleons in a low - density nuclear medium like valence nucleons near the nuclear surface ,
such effective interactions derived from free - space @xmath1 are satisfactory in reproducing experimental nuclear properties .
but it is not so for nucleons in a nuclear medium with density near or beyond nuclear matter saturation density . in this case
it may be necessary to include the effects from brown - rho ( br ) scaling of hadrons and/or three - nucleon forces @xmath5 , effectively changing the free - space @xmath1 into a density - dependent one .
the density - dependent effects from br scaling and @xmath5 are compared with those from empirical skyrme effective interactions . .
And you have already written the first three sentences of the full article: 0.5 cm in treating nuclear many - body problems , one can often reduce the full " many - body problem to a much smaller and more manageable problem , referred to as a model - space problem . in so doing , an important step is to determine the model - space effective interaction @xmath0 . in this paper , we would like to present an introductory and pedagogical review of this topic , especially the derivation of @xmath0 from realistic meson - exchange nucleon - nucleon interactions .
many - body problems are difficult as we are all aware of .
they are particularly so , when a , the number of particles in the system , is large ..
Please generate the next two sentences of the article | in fact a many - body problem with a=3 is already a very hard problem . in the real world , a is usually much larger .
for example , a=18 when the nucleus @xmath6 is treated as an 18-nucleon problem . |
7,915 | Suppose that you have an abstract for a scientific paper: we consider the multiple - access communication problem in a distributed setting for both the additive white gaussian noise channel and the discrete memoryless channel .
we propose a scheme called distributed rate splitting to achieve the optimal rates allowed by information theory in a distributed manner . in this scheme ,
each real user creates a number of virtual users via a power / rate splitting mechanism in the @xmath0-user gaussian channel or via a random switching mechanism in the @xmath0-user discrete memoryless channel . at the receiver ,
all virtual users are successively decoded .
compared with other multiple - access techniques , distributed rate splitting can be implemented with lower complexity and less coordination .
furthermore , in a symmetric setting , we show that the rate tuple achieved by this scheme converges to the maximum equal rate point allowed by the information - theoretic bound as the number of virtual users per real user tends to infinity . when the capacity regions are asymmetric , we show that a point on the dominant face can be achieved asymptotically . finally , when there is an unequal number of virtual users per real user , we show that differential user rate requirements can be accommodated in a distributed fashion . multiple access , rate splitting , successive decoding , stripping , interference cancellation , aloha . .
And you have already written the first three sentences of the full article: we consider the basic multiple - access communication problem in a distributed setting . in gallager
s survey paper @xcite , it is pointed out that the multiple - access problem has been studied from a number of different perspectives , each having its own advantages and shortcomings . in the data networking community ,
a well - known distributed multiple access scheme is aloha @xcite . in aloha.
Please generate the next two sentences of the article | , it is assumed that a collision " happens whenever more than one user transmit simultaneously .
those packets involved in a collision are discarded and retransmitted according to some retransmission probability . |
7,916 | Suppose that you have an abstract for a scientific paper: we present a comparison between the 2001 xmm - newton and 2005 suzaku observations of the quasar , pg1211 + 143 at @xmath0 .
variability is observed in the 7 kev iron k - shell absorption line ( at 7.6 kev in the quasar frame ) , which is significantly weaker in 2005 than during the 2001 xmm - newton observation . from a recombination timescale of @xmath1 years , this implies an absorber density @xmath2@xmath3 , while the absorber column is @xmath4@xmath5 .
thus the sizescale of the absorber is too compact ( pc scale ) and the surface brightness of the dense gas too high ( by 9 - 10 orders of magnitude ) to arise from local hot gas , such as the local bubble , group or warm / hot intergalactic medium ( whim ) , as suggested by mckernan et al .
( 2004 , 2005 ) . instead
the iron k - shell absorption must be associated with an agn outflow with mildly relativistic velocities .
finally we show that the the association of the absorption in pg1211 + 143 with local hot gas is simply a coincidence , the comparison between the recession and iron k absorber outflow velocities in other agn does not reveal a one to one kinematic correlation .
[ firstpage ] accretion , accretion discs atomic processes x - rays : galaxies .
And you have already written the first three sentences of the full article: the cosmological requirement that half the baryons in the universe are in a warm / hot intergalactic medium ( whim ) has motivated uv and x ray absorption line studies to detect this otherwise invisible gas , using absorption against a bright agn to probe the line of sight material ( bregman 2007 ) .
however , most agn ( except blazars ) have intrinsic columns of warm absorbing gas in their nuclei , and the fact that this is generally connected to a nuclear outflow ( blustin et al 2005 ) complicates separating this intrinsic absorption from extrinsic line of sight material using velocity information .
nonetheless , various studies have looked for absorption lines ( predominantly ovii / viii ) as signatures of the whim , though all current detections are more likely to be associated with material in our galactic halo or local group ( bregman & lloyd jones 2007 ) ..
Please generate the next two sentences of the article | these have velocities within a few hundred km / s of the local standard of rest , and indicate columns of ovii / viii @xmath6 @xmath5 , equivalent to hydrogen columns of @xmath7 @xmath5 .
much more controversial was the potential association of substantially higher columns of gas to such local material . |
7,917 | Suppose that you have an abstract for a scientific paper: we compile a sample consisting of 56 radio - quiet active galactic nuclei so as to investigate statistical properties of hot corona of accretion disks from _ asca _ observations .
the black - hole masses in the sample are estimated via several popular methods and the bolometric luminosities from the multi - wavelength continuum .
this allows us to estimate the eddington ratio ( @xmath0 ) so that the undergoing physical processes can be tested via hard x - ray data .
we find a strong correlation between @xmath1 and @xmath2 as @xmath3 with a multivariate regression .
this indicates that the release of gravitational energy in the hot corona is controlled by the eddington ratio .
on the other hand , the correlation between the hard x - ray spectral index ( @xmath4 ) and @xmath2 depends critically on the types of objects : @xmath4 is nearly constant ( @xmath5 ) in broad - line seyfert 1 s ( bls1s ) , whereas @xmath6 in narrow - line seyfert 1 s ( nls1s ) , although not very significant .
we can set constraints on the forms of magnetic stress tensor on the condition that @xmath7 is proportional to the fraction @xmath8 of gravitational energy dissipated in the hot corona and that @xmath8 is proportional to magnetic energy density in the disk .
we find that the shear stress tensor @xmath9 is favored by the correlation in the present sample , where @xmath10 is the gas pressure . .
And you have already written the first three sentences of the full article: accretion onto a supermassive black hole is generally regarded to be powering active galactic nuclei ( agns ) . for a steady keplerian accretion disk around a black hole with mass @xmath11 ,
the released energy via viscosity dissipation is given by @xmath12 where @xmath13 , the eddington luminosity @xmath14 , @xmath15 , @xmath16 , @xmath17 and @xmath18 ( shakura & sunyaev 1973 ) .
it is important to note that @xmath19 is independent of the specific mechanism of viscosity stress . in the regime of the standard accretion disk around a massive black hole.
Please generate the next two sentences of the article | , the disks can not produce x - ray emission .
models of the accretion disks with hot corona have been suggested in order to explain the observed x - ray emission ( liang & price 1977 ) . in a popular model , a fraction @xmath8 of @xmath19 |
7,918 | Suppose that you have an abstract for a scientific paper: we analytically compute correlation and response functions of scalar operators for the systems with galilean and corresponding aging symmetries for general spatial dimensions @xmath0 and dynamical exponent @xmath1 , along with their logarithmic and logarithmic squared extensions , using the gauge / gravity duality .
these non - conformal extensions of the aging geometry are marked by two dimensionful parameters , eigenvalue @xmath2 of an internal coordinate and aging parameter @xmath3 .
we further perform systematic investigations on two - time response functions for general @xmath0 and @xmath1 , and identify the _ growth exponent _ as a function of the scaling dimensions @xmath4 of the dual field theory operators and aging parameter @xmath3 in our theory .
the initial growth exponent is only controlled by @xmath4 , while its late time behavior by @xmath3 as well as @xmath4 .
these behaviors are separated by a time scale order of the waiting time .
we attempt to make contact our results with some field theoretical growth models , such as kim - kosterlitz model at higher number of spatial dimensions @xmath0 .
cquest-2013 - 0593 + taup-2963/13 seungjoon hyun@xmath5 , jaehoon jeong@xmath6 and bom soo kim@xmath7 @xmath8_department of physics , college of science , yonsei university , seoul 120 - 749 , korea _ + @xmath9_center for quantum spacetime , sogang university , seoul 121 - 742 , korea _
+ @xmath10_raymond and beverly sackler school of physics and astronomy , _ +
_ tel aviv university , 69978 , tel aviv , israel _
+ [email protected] , [email protected] , [email protected] .
And you have already written the first three sentences of the full article: non - equilibrium growth and aging phenomena are of great interest due to their wide applications across various scientific fields of study , including many body statistical systems , condensed matter systems , biological systems and so on @xcite-@xcite .
they are complex physical systems , and details of microscopic dynamics are widely unknown .
thus it is best to describe these systems with a small number of variables , their underlying symmetries and corresponding universality classes , which have been focus of nonequilibrium critical phenomena ..
Please generate the next two sentences of the article | one particular interesting class is described by the kardar - parisi - zhang ( kpz ) equation @xcite@xcite .
recently , this class is realized in a clean experimental setup @xcite@xcite , and their exponents for one spatial dimension @xmath11 is confirmed : the roughness @xmath12 , the growth @xmath13 and the dynamical @xmath14 exponents . along with the experimental developments , |
7,919 | Suppose that you have an abstract for a scientific paper: we establish a deformation isomorphism between the algebras of @xmath0-biinvariant compactly supported measures on @xmath1 and @xmath0-conjugation invariant measures on the euclidean space @xmath2 of all hermitian @xmath3-matrices with trace @xmath4
. this isomorphism concisely explains a close connection between the spectral problem for sums of hermititan matrices on one hand and the singular spectral problem for products of matrices from @xmath1 on the other , which has recently been observed by klyachko @xcite . from this deformation
we further obtain an explicit , probability preserving and isometric isomorphism between the banach algebra of bounded @xmath0-biinvariant measures on @xmath1 and a certain ( non - invariant ) subalgebra of the bounded signed measures on @xmath2 .
we demonstrate how this probability preserving isomorphism leads to limit theorems for the singular spectrum of @xmath0-biinvariant random walks on @xmath1 in a simple way .
our construction relies on deformations of hypergroup convolutions and will be carried out in the general setting of complex semisimple lie groups . .
And you have already written the first three sentences of the full article: the spectral problem for possible sums of two random hermitian matrices with given spectra had been a long - standing problem , formulated as horn s conjecture , until it was completely solved only recently by klyachko , knutson and tao ( @xcite , @xcite ) . in @xcite , klyachko then observed a close connection between @xmath0-biinvariant random walks on @xmath1 and random walks on the additive group @xmath2 of all hermitian @xmath3-matrices with trace 0 whose transition probabilities are conjugation - invariant under @xmath0 .
he used this connection to reduce the description of the possible singular spectra of products of random matrices from @xmath1 with given singular spectra to the spectral problem for sums of hermitian matrices . basically , klyachko s observation is a connection between the convolution algebras of the gelfand pairs @xmath5 and @xmath6 .
it is closely related to a similar correspondence between the convolutions of conjugation - invariant measures on a compact lie group ( here @xmath0 ) on one hand and @xmath7-invariant measures on its lie algebra ( here @xmath8 ) on the other , in terms of the so - called wrapping map ( see @xcite and remark [ wrapping ] ) ..
Please generate the next two sentences of the article | klyachko noticed in @xcite , but did not not explain that his connection can be well expressed in terms of hypergroups ; his proof goes via random walks in the group @xmath0 and relies on various identities between the spherical functions of @xmath5 , the characters of @xmath0 and the euclidean group @xmath2 , as well as poisson s summation formula .
the main purpose of the present paper is to clarify and simplify klyachko s approach @xcite by using so - called deformations of hypergroup convolutions by positive semicharacters as introduced in @xcite , @xcite . |
7,920 | Suppose that you have an abstract for a scientific paper: we present lightcurves of the afterglow of grb 050502a , including very early data at @xmath0 s. the lightcurve is composed of unfiltered rotse - iiib optical observations from 44 s to 6 h post - burst , @xmath1-band mdm observations from 1.6 to 8.4 h post - burst , and pairitel @xmath2 observations from 0.6 to 2.6 h post - burst .
the optical lightcurve is fit by a broken power law , where @xmath3 steepens from @xmath4 to @xmath5 at @xmath65700 s. this steepening is consistent with the evolution expected for the passage of the cooling frequency @xmath7 through the optical band . even in our earliest observation at 44 s post - burst
, there is no evidence that the optical flux is brighter than a backward extrapolation of the later power law would suggest .
the observed decay indices and spectral index are consistent with either an ism or a wind fireball model , but slightly favor the ism interpretation .
the expected spectral index in the ism interpretation is consistent within @xmath8 with the observed spectral index @xmath9 ; the wind interpretation would imply a slightly ( @xmath10 ) shallower spectral index than observed . a small amount of dust extinction at the source redshift
could steepen an intrinsic spectrum sufficiently to account for the observed value of @xmath11 . in this picture , the early optical decay , with the peak at or below @xmath12 hz at 44 s , requires very small electron and magnetic energy partitions from the fireball . .
And you have already written the first three sentences of the full article: grb afterglows are typically observed to decay as power laws in time ( as reviewed by , e.g. , * ? ? ?
the leading afterglow model is the synchrotron fireball @xcite .
it describes the afterglow as synchrotron emission from shock - accelerated electrons with a broken power law spectral energy distribution , with several characteristic break frequencies ..
Please generate the next two sentences of the article | when the typical synchrotron frequency ( @xmath13 ) or the cooling frequency ( @xmath7 ) passes through the optical bands , the model predicts a break in the lightcurve .
the fireball model s spectral breaks have different power law indices depending upon the circumburst medium ( as discussed by * ? ? ? |
7,921 | Suppose that you have an abstract for a scientific paper: in this paper we demonstrate that lindblad equations characterized by a random rate variable arise after tracing out a complex structured reservoir .
our results follows from a generalization of the born - markov approximation , which relies in the possibility of splitting the complex environment in a direct sum of sub - reservoirs , each one being able to induce by itself a markovian system evolution .
strong non - markovian effects , which microscopically originate from the entanglement with the different sub - reservoirs , characterize the average system decay dynamics . as an example
, we study the anomalous irreversible behavior of a quantum tunneling system described in an effective two level approximation . stretched exponential and power law decay behaviors arise from the interplay between the dissipative and unitary hopping dynamics . .
And you have already written the first three sentences of the full article: the dynamic of a small quantum system interacting weakly with uncontrollable degrees of freedom is well understood when a markovian approximation applies . in this situation , after tracing - out the environment , the system density matrix evolution can be well approximated by a lindblad equation @xcite . besides that the applicability of the markovian approximation range over many areas of physics @xcite there exist several real systems whose dynamics present strong departures from it .
the main signature of this departure is the presence of strong non - exponential decay behaviors , such as power law and stretched exponential .
some examples are nanocrystal quantum dots under laser radiation schlegel , brokmann , grigolini , superconducting qubits makhlinreport , makhlin , falci , spin environments @xcite , dephasing in atomic and molecular physics @xcite , electron transfer and exciton dynamics in proteins @xcite , and molecular systems maintained in a glassy environment @xcite , to name but a few ..
Please generate the next two sentences of the article | these and another specific experimental situations rise up the necessity of finding formalism and effective evolutions able to describe the corresponding non - markovian dynamics . when the environment is modeled as an infinite set of normal modes , departure from a markov approximation can be related to the corresponding spectral density function .
this situation was extensively studied for the spin - boson and boson - boson models , where exacts solutions are available leggett , grifoni , lang , hanggi , milena . |
7,922 | Suppose that you have an abstract for a scientific paper: we report the serendipitous discovery of a bal qso at z = 2.169 , located 41 southwest of 3c48 .
we present keck lris spectroscopy covering rest frame 1500 to 2300 .
the civ bal has three components and it extends to outflow velocities of at least 12,000 km s@xmath0 .
the bal qso has an intervening low - ionization metal - line absorption system at z = 1.667 which is likely to be a damped ly@xmath1 absorber .
hst images show extended luminous material around the qso , which could be either the host galaxy or the intervening system . .
And you have already written the first three sentences of the full article: broad absorption line quasi stellar objects ( bal qsos ) form a rare class comprising @xmath2% of the qso population at moderate to high redshift ( foltz et al .
the standard view , based largely on estimates of upper limits to resonant scattering by the bal clouds , is that such clouds have a small covering factor as seen from the qso nucleus , implying that essentially all radio - quiet qsos would be classified as bal qsos if observed from the proper angle .
bal qsos appear to be found more frequently among those with enhanced far - ir emission , strong emission , and/or weak or absent [ ] narrow emission lines ( low et al ..
Please generate the next two sentences of the article | 1989 ; boroson & meyers 1992 ; turnshek et al .
while the strong emission might be due to an orientation effect , it seems unlikely that the other properties mentioned would have a strong dependence on viewing angle . |
7,923 | Suppose that you have an abstract for a scientific paper: in this work we study the effects of a longitudinal periodic potential on a parabolic quantum wire defined in a two - dimensional electron gas with rashba spin - orbit interaction . for an infinite wire superlattice
we find , by direct diagonalization , that the energy gaps are shifted away from the usual bragg planes due to the rashba spin - orbit interaction .
interestingly , our results show that the location of the band gaps in energy can be controlled via the strength of the rashba spin - orbit interaction .
we have also calculated the charge conductance through a periodic potential of a finite length via the non - equilibrium green s function method combined with the landauer formalism .
we find dips in the conductance that correspond well to the energy gaps of the infinite wire superlattice . from the infinite wire energy dispersion ,
we derive an equation relating the location of the conductance dips as a function of the ( gate controllable ) fermi energy to the rashba spin - orbit coupling strength .
we propose that the strength of the rashba spin - orbit interaction can be extracted via a charge conductance measurement . .
And you have already written the first three sentences of the full article: during the last two decades there has been much interest in using the electron spin in electronic devices .
this research field , often referred to as spintronics , has already made great impact on metal - based information storage systems .
there are hopes that a similar success can also be achieved in semiconductor based systems @xcite . manipulating the spins of the electrons via external magnetic fields over nanometer length scales.
Please generate the next two sentences of the article | is not considered feasible .
another , more attractive , method is to use electric fields to manipulate electron spins via spin - orbit interaction . |
7,924 | Suppose that you have an abstract for a scientific paper: xte j1946 + 274 = gro j1944 + 26 is a 15.8 s be / x - ray pulsar discovered simultaneously in 1998 september with the burst and transient source experiment ( batse ) on the _ compton gamma ray observatory ( cgro ) _ and the all - sky monitor ( asm ) on the _ rossi x - ray timing explorer ( rxte)_. here we present new results from batse and _ rxte _ including a pulse timing analysis , spectral analysis , and evidence for an accretion disk .
our pulse timing analysis yielded an orbital period of 169.2 days , a moderate eccentricity of @xmath0 , and implied a mass function of 9.7 m@xmath1 .
we observed evidence for an accretion disk , a correlation between measured spin - up rate and flux , which was fitted to obtain a distance estimate of @xmath2 kpc .
xte j1946 + 274 remained active from 1998 september - 2001 july , undergoing 13 outbursts that were not locked in orbital phase . comparing _
rxte _
pca observations from the initial bright outburst in 1998 and the last pair of outbursts in 2001 , we found energy and intensity dependent pulse profile variations in both outbursts and hardening spectra with increasing intensity during the fainter 2001 outbursts . in 2001 july , optical h@xmath3 observations indicate a density perturbation appeared in the be disk as the x - ray outbursts ceased .
we propose that the equatorial plane of the be star is inclined with respect to the orbital plane in this system and that this inclination may be a factor in the unusual outburst behavior of the system . .
And you have already written the first three sentences of the full article: be / x - ray binaries are the most common type of accreting x - ray pulsar systems .
they consist of a pulsar and a be ( or oe ) star , a main sequence star of spectral type b ( or o ) that shows balmer emission lines ( see e.g. , slettebak 1988 and coe 2000 for reviews . )
the line emission is believed to be associated with an equatorial outflow of material expelled from the rapidly rotating be star which probably forms a quasi - keplerian disk near the be star @xcite ..
Please generate the next two sentences of the article | x - ray outbursts are produced when the pulsar interacts with this disk .
be / x - ray binaries typically show two types of outburst behavior : ( a ) giant outbursts ( or type ii ) , characterized by high luminosities ( @xmath4 ergs s@xmath5 ) and high spin - up rates ( i.e. , a significant increase in pulse frequency ) and ( b ) normal outbursts ( or type i ) , characterized by lower luminosities ( @xmath6 ergs s@xmath5 ) , low spin - up rates ( if any ) , and recurrence at the orbital period @xcite . as a population |
7,925 | Suppose that you have an abstract for a scientific paper: virtual knots were first introduced by l. kauffman , which are a generalization of classical knots and links . they lead us to the notion of virtual braids , which are closely related with welded braids of r. fenn , r. rimnyi and c. rourke .
it is proved that any virtual knot is uniquely described as the closure of a virtual braid modulo certain basic moves .
this is analogous to the alexander and markov theorem for classical knots and braids .
a similar result is proved for welded knots and braids _ mathematics subject classification _ : primary 57m25 . _
key words and phrases _ : virtual knot , braid , welded braid , alexander and markov theorem , exchange move . .
And you have already written the first three sentences of the full article: in 1996 , l. kauffman introduced the notion of a virtual knot , which is motivated by study of knots in a thickened surface and abstract gauss codes , cf . .
according to m. goussarov , m. polyak and o. viro , two classical knot diagrams represent the same knot type if and only if they represent the same virtual knot type .
thus , the notion of a virtual knot is a generalization of a classical knot in 3-space . some properties and applications of virtual knots.
Please generate the next two sentences of the article | are found in , etc . using the basic moves appearing in the definition of a virtual knot
, we obtain the notion of a virtual braid ( cf . ) . |
7,926 | Suppose that you have an abstract for a scientific paper: we study the possible tetraquark interpretation of light scalar meson states @xmath0 , @xmath1 , @xmath2 , @xmath3 within the framework of the non - relativistic potential model .
the wave functions of tetraquark states are obtained in a space spanned by multiple gaussian functions .
we find that the mass spectra of the light scalar mesons can be well accommodated in the tetraquark picture if we introduce a three - body quark interaction in the quark model .
using the obtained multiple gaussian wave functions , the decay constants of tetraquarks are also calculated within the `` fall apart '' mechanism . .
And you have already written the first three sentences of the full article: tetraquarks were proposed decades ago .
early in 1977 , jaffe make a calculation using the color - magnetic interaction in the bag model @xcite . he suggested that the light scalar mesons below 1 gev , @xmath0 , @xmath1 , @xmath2 and @xmath3 , be interpreted as a nonet of light tetraquarks . in recent years , the light scalar mesons are observed in decays of charmed mesons .
the @xmath3 is observed as a peak in decay @xmath4 @xcite and @xmath2 in @xmath5 @xcite . from the process @xmath6 ,.
Please generate the next two sentences of the article | bes collaboration determined the pole position of @xmath3 to be @xmath7 mev@xcite . also bes collaboration found a @xmath2 like structure in the decay @xmath8@xcite .
the accumulation of experimental data allows us to study the structure of the light scalar nonet based on their decay properties @xcite . as a many - body system , |
7,927 | Suppose that you have an abstract for a scientific paper: the orbits of the group @xmath0 of upper - triangular matrices acting on @xmath1-nilpotent complex matrices via conjugation are classified via oriented link patterns , generalizing a. melnikov s classification of the @xmath0-orbits on upper - triangular such matrices .
the orbit closures as well as the `` building blocks '' of minimal degenerations of orbits are described .
the classification uses the theory of representations of finite - dimensional algebras .
furthermore , we initiate the study of the @xmath0-orbits on arbitrary nilpotent matrices . .
And you have already written the first three sentences of the full article: the study of adjoint actions and variants thereof , and in particular the classification of orbits for such actions and the description of the orbit closures , are a common theme in lie representation theory .
the archetypical example is the jordan - gerstenhaber theory for the conjugacy classes of complex @xmath2-matrices . +
a more recent case is a. melnikov s study of the action of the borel subgroup @xmath0 acting on upper - triangular @xmath1-nilpotent matrices via conjugation @xcite ..
Please generate the next two sentences of the article | the orbits and their closures are described there combinatorially in terms of so - called link patterns , which we will recapitulate in section [ rom ] .
+ our aim in this paper is to generalize the work of a. melnikov by extending the variety of upper - triangular @xmath1-nilpotent matrices to all @xmath1-nilpotent matrices . the basic setup to reach this goal is a translation of the classification problem to a problem in representation theory of finite - dimensional algebras . |
7,928 | Suppose that you have an abstract for a scientific paper: quantum steering is a relatively simple test for quantumness of correlations , proving that the values of quantum - mechanical measurement outcomes come into being only in the act of measurement . by exploiting quantum correlations
alice can influence steer
bob s physical system in a way inaccessible in classical world , leading to violation of some inequalities . demonstrating this and similar quantum effects for systems of
increasing size , approaching even the classical limit , is a long - standing challenging problem .
here we provide experimentally feasible signature of unbounded violation of a steering inequality .
we derive its universal form where tolerance for measurement - setting - errors is explicitly build - in by means of the deutsch - maassen - uffink uncertainty relation .
then , generalizing the mutual unbiasedness , we apply the inequality to the multi - singlet and multi - particle bipartite bell - state . however , the method is general and opens the possibility of employing multi - particle bipartite steering for randomness certification and development of quantum technologies , e.g. random access codes . in their famous paper ,
einstein , podolsky and rosen ( epr ) highlighted the phenomenon of entanglement @xcite : it is possible to see perfect correlations between measurement outcomes obtained by two observers , alice and bob , at distant locations , while for each observer his / her outcomes appear to be statistically random .
these are the epr correlations .
validation of entanglement requires designing a specific experimental scenario where measurements on a quantum state give outcomes which violate a classical inequality .
the inequality can be constructed , for example , on the basis of probability distribution satisfying the kolmogorov axioms .
its unbounded violation is equivalent to observation of the epr correlations which become more and more pronounced when size of a system increases , reaching even classical limit of macroscopic population....
And you have already written the first three sentences of the full article: ms & ph supervised the project , suggested the idea and its physical implementation .
they provided the discussion of results and wrote up the paper .
ar participated in discussions , suggested and proved the technical version of the theorem ..
Please generate the next two sentences of the article | ab developed numerical methods and analytical computations supporting the proposition in discussion with ms .
ab prepared the figures . |
7,929 | Suppose that you have an abstract for a scientific paper: intricate spin textures in helimagnets , identified as stable topological skyrmions , were observed experimentally , where skyrme lattice was supposed to exhibit symmetric structures in the ground state .
we show the possibility of asymmetric skyrmions in a helimagnetic model , for individual skyrmion as well as for the hexagonal skyrme crystal with higher charge , as perturbative deformation and stabilization of exact ferromagnetic solitons .
such nonsymmetric configurations for the skyrme lattice , predicted here theoretically , need to be verified in precision experiments . _
key words _ : solitons with topological charge , exact skyrmions in ferromagnet , asymmetric skyrmions and skyrme crystals in helimagnets , perturbative solutions + .
And you have already written the first three sentences of the full article: unusual magnetic behavior of helimagnet mnsi unusual , which triggered the suspicion , that the magnetic states in such helimagnetic materials might be of topological origin opological , top2,bogdannature06,bogdanmnsi , is confirmed as skyrmions in quantum hall ( qh ) qhexperim and small angle neutron scattering ( sans ) experiments @xcite .
these experiments , though made pioneering observations , could give only indirect evidence for the existence of skyrmion spin textures , due to their confinement in the momentum space .
however , more recently , in a real space experiment with lorentz transmission electron microscopy ( tem ) , direct photographic evidence of skyrmion crystals was obtained in a thin film of helimagnet fe@xmath0co@xmath0si , on a plane perpendicular to the applied magnetic field @xcite ..
Please generate the next two sentences of the article | skyrmion crystals were found to be in a beautiful hexagonal form , with the localized individual skyrmions serving as its constituent molecules , extended over lattice spacing of 30 nm range . for theoretical description of these fascinating experimental observations in helimagnets ,
the accepted basic model is given by a ferromagnetic spin exchange hamiltonian in combination with a dzyaloshinskii - moriya ( dm ) interaction bogdanmnsi , lorentzexp , helimodel , helimodelprl10 . |
7,930 | Suppose that you have an abstract for a scientific paper: transmission properties of one - dimensional lossy photonic crystals composed of negative and positive refractive index layers with one lossless defect layer at the center of the crystal are investigated by the characteristic matrix method .
the results show that as the refractive index and thickness of the defect layer increase the frequency of the defect mode decreases .
in addition , it is shown that the frequency of the defect mode is sensitive to the incidence angle , polarization and physical properties of the defect layer but it is insensitive to the small lattice loss factor .
the height of the defect mode is very sensitive to the loss factor , incidence angle , polarization , refractive index and thickness of the defect layer .
it was also shown that the height and the width of the defect mode are affected by the number of the lattice period and the loss factor .
the results can lead to designing new types of narrow filter structures and other optical devices . .
And you have already written the first three sentences of the full article: photonic crystals ( pcs ) were first introduced theoretically by yablonovitch @xcite . , and experimentally by john @xcite .
pcs , constructed with periodic structure of artificial dielectrics or metallic materials , have attracted many researchers in the past two decades for their unique electromagnetic properties and scientific and engineering applications @xcite .
these crystals indicate a range of forbidden frequencies , called photonic band gap , as a result of bragg scattering of the electromagnetic waves passing through such a periodical structure @xcite . as the periodicity of the structure.
Please generate the next two sentences of the article | is broken by introducing a layer with different optical properties , a localized defect mode will appear inside the band gap .
enormous potential applications of pcs with defect layers in different areas , such as light emitting diodes , filters and fabrication of lasers have made such structures are interesting research topic in this field . |
7,931 | Suppose that you have an abstract for a scientific paper: neutron stars inspiralling into a stellar envelope can accrete at rates vastly exceeding the eddington limit if the flow develops pressures high enough to allow neutrinos to radiate the released gravitational energy .
it has been suggested that this hypercritical mode of accretion leads inevitably to the formation of stellar mass black holes during common envelope evolution .
we study the hydrodynamics of this flow at large radii ( @xmath0 ) , and show that for low mach number flows , in two dimensions , modest density gradients in the stellar envelope suffice to produce a hot , advection dominated accretion disk around the accreting object .
the formation of outflows from such a disk is highly probable , and we discuss the impact of the resultant mass loss and feedback of energy into the envelope for the survival of the neutron star . unless outflows are weaker than those inferred for well observed accreting systems , we argue that in most cases insufficient accretion occurs to force collapse to a black hole before the envelope has been ejected .
this conclusions is of interest for black hole formation in general , for some models of gamma ray bursts , and for predictions of the event rate in future ligo observations . .
And you have already written the first three sentences of the full article: common envelope evolution , in which the components of a binary system are engulfed by a common gaseous envelope , is a brief but crucial phase in the formation of many compact binary systems .
drag forces , due to velocity differences between the orbiting components of the binary and the surrounding gas , work to shrink the binary orbit , while the potential energy released acts to expel the common envelope .
extensive numerical work ( e.g. bodenheimer & taam 1984 ; livio & soker 1988 ; taam , bodenheimer & rozyczka 1994 ; sandquist et al ..
Please generate the next two sentences of the article | 1998 ) has only partially succeeded in reducing the large uncertainties surrounding the efficiency of this process ( iben & livio 1993 ; livio 1994 ; rasio & livio 1996 ) . for neutron stars , an equally fundamental uncertainty concerns the _ accretion rate _ during the common envelope phase . at the densities of a typical giant envelope , the bondi - hoyle accretion rate @xmath1 for
an inspiralling neutron star would be extremely large , typically of the order of @xmath2 , and often much larger still . |
7,932 | Suppose that you have an abstract for a scientific paper: resonant inelastic x - ray scattering ( rixs ) at the @xmath0-edge of transition metal elements is now commonly used to probe single magnon excitations . here
we show that single magnon excitations can also be measured with rixs at the @xmath1-edge of the surrounding ligand atoms when the center heavy metal elements have strong spin - orbit coupling .
this is demonstrated with oxygen @xmath1-edge rixs experiments on the perovskite sr@xmath2iro@xmath3 , where low energy peaks from single magnon excitations were observed .
this new application of rixs has excellent potential to be applied to a wide range of magnetic systems based on heavy elements , for which the @xmath0-edge rixs energy resolutions in the hard x - ray region is usually poor .
_ keywords : single magnon excitation , rixs , oxygen @xmath1-edge , iridates _
+ recently , the resonant inelastic x - ray scattering technique has achieved great progress in condensed matter physics research @xcite .
it has now been clearly demonstrated that rixs is not only suitable for studying charge and orbital excitations , but it is also a powerful tool to probe magnetic dynamics .
with rixs at the @xmath0-edge of the magnetic elements , the magnetic dispersion curves were mapped out on various transition metal compounds such as cuprates @xcite and iridates @xcite .
although the leading term of the photon - electron interaction does not directly couple to the spin , the strong spin - orbit coupling ( soc ) of the core level _ p _
states accessed at the @xmath0-edge makes direct spin - flip scattering possible in the rixs process @xcite . combined with the large energy transfer and appreciable momentum transfer capability of x - ray scattering
, this makes rixs an attractive tool to measure magnetic dispersions , especially in situations where small sample volumes make inelastic neutron scattering difficult to apply . depending on the resonant energy of the targeted element , rixs
is naturally divided into two classes : soft x - ray....
And you have already written the first three sentences of the full article: we thank fan wei and jeroen van den brink for helpful discussions .
x liu was supported by the strategic priority research program of the chinese academy of sciences ( grant no : xdb07020200 ) .
the work at brookhaven national laboratory was supported by the u.s ..
Please generate the next two sentences of the article | department of energy ( doe ) , division of materials science , under contract no .
de - sc0012704 . |
7,933 | Suppose that you have an abstract for a scientific paper: clouds of metal - bearing condensates play a critical role in shaping the emergent spectral energy distributions of the coolest classes of low - mass stars and brown dwarfs , l and t dwarfs . because condensate clouds in planetary atmospheres show distinct horizontal structure , we have explored a model for partly cloudy atmospheres in brown dwarfs .
our model successfully reproduces the colors and magnitudes of both l and t dwarfs for the first time , including the unexpected brightning of the early- and mid - type t dwarfs at j - band , provided that clouds are rapidly removed from the photosphere at t@xmath0 @xmath1 1200 k. the clearing of cloud layers also explains the surprising persistence and strengthening of gaseous feh bands in early- and mid - type t dwarfs .
the breakup of cloud layers is likely driven by convection in the troposphere , analogous to phenomena observed on jupiter .
our results demonstrate that planetary - like atmospheric dynamics must be considered when examining the evolution of free - floating brown dwarfs .
# 1/#2.1em .5ex-.1em /-.15em.25ex # 1to 0pt#1 # 1 .
And you have already written the first three sentences of the full article: the recent discovery of a vast population of free - floating brown dwarfs in the vicinity of the sun @xcite has led to the definition of two new spectroscopic classes , l dwarfs and t dwarfs .
these are the first additions to the standard stellar sequence in over 60 years , encompassing objects cooler than the m spectral class .
l dwarfs @xcite are characterized by absorption bands of metal hydrides ( e.g. , feh , crh , and mgh ) , strong alkali lines ( li , na , k , rb , and cs ) , and h@xmath2o and co absorption in the near - infrared ..
Please generate the next two sentences of the article | below effective temperatures @xmath3 , co reduces to @xmath4 @xcite , a molecule which has distinct absorption bands at 1.6 and @xmath5 .
objects exhibiting these @xmath4 features have grossly different spectroscopic and photometric properties as compared to l dwarfs , and are designated t dwarfs @xcite . |
7,934 | Suppose that you have an abstract for a scientific paper: we propose to employ the quasiisotropic metamaterial ( qimm ) slab to construct a polarization insensitive lens , in which both e- and h - polarized waves exhibit the same refocusing effect . for shallow incident angles ,
the qimm slab will provide some degree of refocusing in the same manner as an isotropic negative index material .
the refocusing effect allows us to introduce the ideas of paraxial beam focusing and phase compensation by the qimm slab . on the basis of angular spectrum representation ,
a formalism describing paraxial beams propagating through a qimm slab is presented . because of the negative phase velocity in the qimm slab , the inverse gouy phase shift and the negative rayleigh length of paraxial gaussian beam are proposed .
we find that the phase difference caused by the gouy phase shift in vacuum can be compensated by that caused by the inverse gouy phase shift in the qimm slab .
if certain matching conditions are satisfied , the intensity and phase distributions at object plane can be completely reconstructed at image plane .
our simulation results show that the superlensing effect with subwavelength image resolution could be achieved in the form of a qimm slab . .
And you have already written the first three sentences of the full article: about forty years ago , veselago firstly introduced the concept of left - handed material ( lhm ) in which both the permittivity @xmath0 and the permeability @xmath1 are negative @xcite .
he predicted that lhm would have unique and potentially interesting properties , such as the negative refraction index , the reversed doppler shift and the backward cerenkov radiation .
veselago pointed out that electromagnetic waves incident on a planar interface between a regular material and a lhm will undergo negative refraction ..
Please generate the next two sentences of the article | hence a lhm planar slab can act as a lens and focus waves from a point source .
lhm did not receive much attention as it only existed in a conceptual form . |
7,935 | Suppose that you have an abstract for a scientific paper: we study transport across p - n junctions of gapped two - dimensional semi - dirac materials : nodal semimetals whose energy bands disperse quadratically and linearly along distinct crystal axes .
the resulting electronic properties relevant to materials such as tio@xmath0/vo@xmath0 multilayers and @xmath1-(bedt - ttf)@xmath0i@xmath2 salts continuously interpolate between those of mono- and bi - layer graphene as a function of propagation angle .
we demonstrate that tunneling across the junction depends on the orientation of the tunnel barrier relative to the crystalline axes , leading to strongly non - monotonic current - voltage characteristics , including negative differential conductance in some regimes . in multi - valley systems
these features provide a natural route to engineering valley - selective transport . _
introduction. _ quantum tunneling is at the heart of modern semiconductor technology : the simplest incarnation of the venerable p - n junction relies on controlling electron tunneling primarily by tuning device parameters such as the width of the depletion region and its characteristic energy barrier .
richer behavior more sensitive to microscopic material properties is possible in the presence of multiple bands , where applied fields can induce interband landau - zener transitions @xcite , reflected in highly nonlinear current - voltage ( @xmath3 ) characteristics .
quantum interference , on the other hand , has historically been of less relevance to semiconductor devices , and was largely ignored in this context until the recent revolution in two - dimensional materials : for instance , interference phenomena stemming from the dirac nature of electronic quasiparticles in graphene have been successfully probed in transport experiments .
recent work @xcite involving one of the present authors examined the interplay of interference and tunneling in bilayer graphene ( blg ) , whose pristine electronic dispersion consists of a pair of bands touching quadratically at isolated....
And you have already written the first three sentences of the full article: in this section , we focus on the tunneling amplitudes at finite @xmath52 . we rewrite eq .
( [ eq : energy ] ) of the main text as p_x(x)^4+p_x(x)^3+p_x(x)^2+p_x(x)+m_0+(1-v(x)^2)=0 , [ eq : sol ] where @xmath114 and @xmath115 ; @xmath116 and @xmath117 , while @xmath118 with @xmath119 ; @xmath120 , @xmath121 , and @xmath122 , where @xmath123 .
note that we have written eq ..
Please generate the next two sentences of the article | ( 11 ) in dimensionless units . in the barrier regime @xmath124 , the effective wkb action @xmath125 leads to four solutions : s_i = s_i+i s_i , where @xmath126 , and all @xmath40 and @xmath41 are real numbers .
of these four solutions , two propagate to the right and two to the left |
7,936 | Suppose that you have an abstract for a scientific paper: we propose a model for resonant josephson tunneling through quantum dots that accounts for cooper pair - breaking processes in the superconducting leads caused by a magnetic field or spin - flip scattering .
the pair - breaking effect on the critical supercurrent @xmath0 and the josephson current - phase relation @xmath1 is largely due to the modification of the spectrum of andreev bound states below the reduced ( abrikosov - gorkov ) quasiparticle gap . for a quantum dot formed in a quasi - one - dimensional channel ,
both @xmath0 and @xmath1 can show a significant magnetic field dependence induced by pair breaking despite the suppression of the orbital magnetic field effect in the channel .
this case is relevant to recent experiments on quantum dot josephson junctions in carbon nanotubes .
pair - breaking processes are taken into account via the relation between the andreev scattering matrix and the quasiclassical green functions of the superconductors in the usadel limit . .
And you have already written the first three sentences of the full article: since its discovery the josephson effect @xcite has been studied for a variety of superconducting weak links @xcite .
the research has recently entered a new phase with the experimental realization of quantum dot weak links exploiting electronic properties of finite - length carbon nanotubes coupled to superconducting leads @xcite . in particular , for the first time since its theoretical prediction @xcite resonant josephson tunneling through discrete electronic states has been observed in carbon nanotube quantum dots @xcite . as demonstrated in refs . , the novel type of weak links exhibits transistor - like functionalities , e.g. a periodic modulation of the critical current with a gate voltage tuning successive energy levels in the dot on- and off - resonance with the fermi energy in the leads .
this property has already been implemented in a recently proposed carbon nanotube superconducting quantum interference device ( cnt - squid ) @xcite with possible applications in the field of molecular magnetism ..
Please generate the next two sentences of the article | motivated by the experiments on resonant josephson tunneling , in this paper we investigate theoretically how robust it is with respect to pair - breaking perturbations in the superconducting leads .
cooper pair breaking can be induced by a number of factors , e.g. by paramagnetic impurities @xcite , an external magnetic field @xcite or by structural inhomogeneities producing spatial fluctuations of the superconducting coupling constant @xcite . |
7,937 | Suppose that you have an abstract for a scientific paper: the evolution of grain structures in materials is a complex and multiscale process that determines the material s final properties @xcite .
understanding the dynamics of grain growth is a key factor for controlling this process .
we propose a phenomenological approach , based on a nonlinear , discrete mass transfer equation for the evolution of an arbitrary initial grain size distribution .
transition rates for mass transfer across grains are assumed to follow the arrhenius law , but the activation energy depends on the degree of amorphization of each grain .
we argue that the magnitude of the activation energy controls the final ( sintered ) grain size distribution , and we verify this prediction by numerical simulation of mass transfer in a one - dimensional grain aggregate .
[ multiblock footnote omitted ] .
And you have already written the first three sentences of the full article: ceramic materials have applications in many fields of science and engineering @xcite . in particular , the efficient production of dense ceramics with nanosized grains using ultrafine powders is a subject of increased attention . the most common method for achieving densification in ceramics is solid - state sintering , a thermally activated process that involves the diffusion and redistribution of mass by means of various physical processes , leading to a compactified and consolidated final structure . in the case of nanosized powder compacts ,
a major concern is the considerable grain growth during the densification process .
special consolidation techniques such as hot isostatic pressing , spark plasma and microwave sintering in many cases successfully limit this undesirable phenomenon ..
Please generate the next two sentences of the article | the addition of dopants able to limit grain boundary migration is another effective option .
a very effective way to limit grain growth is to promote densification at a lower sintering temperature @xcite . |
7,938 | Suppose that you have an abstract for a scientific paper: _ context : _ characterization of instrumental effects in astronomical imaging is important in order to extract accurate physical information from the observations . the measured image in a real optical instrument is usually represented by the convolution of an ideal image with a point spread function ( psf ) .
additionally , the image acquisition process is also contaminated by other sources of noise ( read - out , photon - counting ) .
the problem of estimating both the psf and a denoised image is called blind deconvolution and is ill - posed .
_ aims : _ we propose a blind deconvolution scheme that relies on image regularization .
contrarily to most methods presented in the literature , our method does not assume a parametric model of the psf and can thus be applied to any telescope . _
methods : _ our scheme uses a wavelet analysis prior model on the image and weak assumptions on the psf .
we use observations from a celestial transit , where the occulting body can be assumed to be a black disk .
these constraints allow us to retain meaningful solutions for the filter and the image , eliminating trivial , translated and interchanged solutions . under an additive gaussian noise assumption
, they also enforce noise canceling and avoid reconstruction artifacts by promoting the whiteness of the residual between the blurred observations and the cleaned data . _
results : _ our method is applied to synthetic and experimental data . the psf is estimated for the secchi / euvi instrument using the 2007 lunar transit , and for sdo / aia using the 2012 venus transit .
results show that the proposed non - parametric blind deconvolution method is able to estimate the core of the psf with a similar quality to parametric methods proposed in the literature .
we also show that , if these parametric estimations are incorporated in the acquisition model , the resulting psf outperforms both the parametric and non - parametric methods . .
And you have already written the first three sentences of the full article: deconvolution is an ubiquitous data processing method that arises in a variety of applications , _
e.g. _ , biomedical imaging @xcite , astronomy , remote sensing @xcite and video and photo enhancement @xcite .
formally , this problem amounts to recovering a signal @xmath0 from _ blurred _ and _ corrupted _ observations @xmath1 : @xmath2 where @xmath3 stands for the _ convolution _ operation between @xmath0 and some other signal @xmath4 , while @xmath5 is a general function accounting for some corrupting noise , _.
Please generate the next two sentences of the article | e.g. _ , @xmath6 under an additive corruption model with some ( gaussian ) noise @xmath7 .
for instance , when a scene is captured by an optical instrument , the observation is a blurred or degraded version of the original image , corrupted by noise and by some effects due to the instrument ( motion , out - of - focus , light scattering , ... ) . in such a case , |
7,939 | Suppose that you have an abstract for a scientific paper: we study numerically the dynamical system of a two - electron atom with the darwin interaction as a model to investigate scale - dependent effects of the relativistic action - at - a - distance electrodynamics .
this dynamical system consists of a small perturbation of the coulomb dynamics for energies in the atomic range .
the key properties of the coulomb dynamics are : ( i ) a peculiar mixed - type phase space with sparse families of stable non - ionizing orbits and ( ii ) scale - invariance symmetry , with all orbits defined by an arbitrary scale parameter .
the combination of this peculiar chaotic dynamics ( ( i ) and ( ii ) ) , with the scale - dependent relativistic corrections ( darwin interaction ) generates the phenomenon of scale - dependent stability : we find numerical evidence that stable non - ionizing orbits can exist only for a discrete set of resonant energies .
the fourier transform of these non - ionizing orbits is a set of sharp frequencies .
the energies and sharp frequencies of the non - ionizing orbits we study are in the quantum atomic range .
the coulomb dynamical system of the helium atom is a very peculiar chaotic system that exhibits arnold diffusion@xcite , and with a typical trajectory having an infinity of possible time - asymptotic final states .
for example , almost all negative - energy trajectories of coulombian helium display the generic phenomenon of ionization , namely , the ejection of one electron@xcite . several nonlinear dynamical systems share this property of having more than one time - asymptotic final state , with the respective basins for each outcome having a complicated structure in initial condition space@xcite . the numerical work on this paper
is based on stable coulombian orbits of a two - electron atom that do not ionize for several millions of turns of one electron around the nucleus .
it is a property of the coulomb dynamics of a two - electron atom that most initial conditions with a negative energy ionize very quickly in about....
And you have already written the first three sentences of the full article: the wheeler - feynman@xciteelectrodynamics developed from the schwarzschild - tetrode - fokker@xcite direct - interaction functional .
equations of motion are derived from hamilton s principle for the action integral @xmath5 where the four - vector @xmath6 represents the four - position of particle @xmath7 parametrized by arc - length @xmath8 , double bars indicate quadri - vector modulus @xmath9 and the dot indicates the usual minkowski relativistic scalar product of four - vectors .
( integration is to be carried over the hole particle trajectories , at least formally ) ..
Please generate the next two sentences of the article | the above action integral describes an interaction at the advanced and retarded light - cones with an electromagnetic potential given by half the sum of the advanced and retarded linard - wierchert potentials @xcite .
wheeler and feynman showed that electromagnetic phenomena can be described by this direct action - at - a - distance theory in complete agreement with maxwell s theory as far as the classical experimental consequences@xcite . |
7,940 | Suppose that you have an abstract for a scientific paper: in this paper we establish new restrictions on symplectic embeddings of certain convex domains into symplectic vector spaces .
these restrictions are stronger than those implied by the ekeland - hofer capacities . by refining an embedding technique due to guth
, we also show that they are sharp . .
And you have already written the first three sentences of the full article: consider @xmath0 equipped with coordinates @xmath1 and its standard symplectic form @xmath2 let @xmath3 denote the ball of radius @xmath4 in @xmath5 .
gromov s nonsqueezing theorem states that there is no symplectic embedding of @xmath6 into @xmath7 for @xmath8 , @xcite .
the following analogous problem remains open ..
Please generate the next two sentences of the article | * question 1 . *
_ what , if any , is the smallest value of @xmath9 such that there exists a symplectic embedding of @xmath10 into @xmath11 ? _ prior to the current paper , the most that could be said is that if such an emebedding exists , then @xmath4 must be at least @xmath12 . |
7,941 | Suppose that you have an abstract for a scientific paper: the rare decays @xmath0 and @xmath1 can occur only via annihilation type diagrams in the standard model .
we calculate these decays in perturbative qcd approach .
we found that the calculated branching ratio of @xmath0 agreed with the data which had been observed in the kek and slac @xmath2 factories . while the decay @xmath1 has a very small branching ratio at @xmath3 , due to the suppression from ckm matrix elements @xmath4 .
( 0,0)(-320,-320 ) ( 0,32)*hep - ph/0210206 * ( 0,15)bihep - th-2002 - 47 ( 0,0)dpnu-02 - 31 .
And you have already written the first three sentences of the full article: the rare @xmath2 decays are being measured at @xmath2 factories in kek and slac .
the generalized factorization approach has been applied to the theoretical treatment of non - leptonic @xmath2 decays @xcite .
it is a great success in explaining many decay branching ratios @xcite ..
Please generate the next two sentences of the article | the factorization approach ( f.a . ) is a rather simple method .
some efforts have been made to improve their theoretical application @xcite and to understand the reason why the f.a . |
7,942 | Suppose that you have an abstract for a scientific paper: we study the fidelity susceptibility in the two - dimensional(2d ) transverse field ising model and the 2d xxz model numerically . it is found that in both models , the fidelity susceptibility as a function of the driving parameter diverges at the critical points .
the validity of the fidelity susceptibility to signal for the quantum phase transition is thus verified in these two models .
we also compare the scaling behavior of the extremum of the fidelity susceptibility to that of the second derivative of the ground state energy . from those results , the theoretical argument that fidelity susceptibility is a more sensitive seeker for a second order quantum phase transition is also testified in the two models . .
And you have already written the first three sentences of the full article: fidelity , a concept emerging from quantum information theory , has recently become an attractive approach towards the study of critical phenomena in condensed matter physics . in a quantum many - body system ,
the quantum phase transition is completely driven by the quantum fluctuation in the ground state and is incarnated by an abrupt change in the qualitative structure of the ground state wavefunction as the system varies across the critical point @xcite . therefore
, being a measure of the similarity between two states , the fidelity is excepted to show a dramatic change across the transition points ..
Please generate the next two sentences of the article | this motivated people to start exploring its role played in quantum phase transitions @xcite .
moreover , as the fidelity can be viewed as a space geometrical quantity , no a priori knowledge of the order parameter and symmetry breaking of the system is required . |
7,943 | Suppose that you have an abstract for a scientific paper: in this paper we discuss the excess gamma rays from the galactic center , the wmap haze and the cogent and dama results in wimpless models . at the same time
we also investigate the low energy constraints from the anomalous magnetic moment of leptons and from some lepton flavor violating decays . it is found that , for scalar or vector wimpless dark matter , neither the wmap haze nor the cogent and dama observations could be explained simultaneously with the excess gamma rays from the galactic center . as to fermion wimpless dark matter
, it is only marginally possible to accommodate the cogent and dama results with the excess gamma rays from the galactic center with vector connector fields . on the other hand
, only scalar connector fields could interpret the wmap haze concerning the constraints of anomalous magnetic moment of leptons .
furthermore , if there is only one connector field for all the charged leptons , some lepton flavor violating decays could happen with too large branching ratios severely violating the experimental bounds . .
And you have already written the first three sentences of the full article: there are lots of gravitational evidences suggesting the dominance of dark matter ( dm ) over baryonic visible matter in our universe , though little is known about its non - gravitational interaction . if dm can annihilate or decay into the standard model ( sm ) particles , gamma rays will be generated either directly or by the final state radiation , inverse compton scattering and bremsstrahlung of the final charged particles .
as these gamma rays depend on the dm density as @xmath0 for annihilations and @xmath1 for decays , they might be detectable at locations with very high density of dark matter , such as the galactic center ( gc ) .
recently hooper and goodenough @xcite investigated the gamma rays from the gc using the first two years of data from the fermi gamma ray space telescope ..
Please generate the next two sentences of the article | they modeled the backgrounds and found that the morphology and spectrum of the gamma rays between @xmath2 and @xmath3 from the gc can be well understood .
however excess emission of gamma rays seems to be present within @xmath2 degree of the gc . |
7,944 | Suppose that you have an abstract for a scientific paper: we present alma ( @xmath0 ) ( rest frequency 492 ghz ) observations for a sample of 13 strongly - lensed dusty star - forming galaxies originally discovered at 1.4 mm in a blank - field survey by the south pole telescope .
we compare these new data with available observations from the literature , allowing a study of the ism properties of @xmath1 extreme dusty star - forming galaxies spanning a redshift range @xmath2 . using the line as a tracer of the molecular ism
, we find a mean molecular gas mass for spt - dsfgs of @xmath3 m@xmath4 .
this is in tension with gas masses derived via low-@xmath5 @xmath6co and dust masses ; bringing the estimates into accordance requires either ( a ) an elevated co - to - h@xmath7 conversion factor for our sample of @xmath8 and a gas - to - dust ratio @xmath9 , or ( b ) an high carbon abundance @xmath10 . using observations of a range of additional atomic and molecular lines ( including , , and multiple transitions of co )
, we use a modern photodissociation region code ( 3d - pdr ) to assess the physical conditions ( including the density , uv radiation field strength , and gas temperature ) within the ism of the dsfgs in our sample .
we find that the ism within our dsfgs is characterised by dense gas permeated by strong uv fields .
we note that previous efforts to characterise pdr regions in dsfgs may have significantly under - estimated the density of the ism .
combined , our analysis suggests that the ism of extreme dusty starbursts at high redshift consists of dense , carbon - rich gas not directly comparable to the ism of starbursts in the local universe .
galaxies : high - redshift galaxies : ism gravitational lensing : strong galaxies : evolution galaxies : formation .
And you have already written the first three sentences of the full article: understanding the properties and behaviour of the interstellar medium ( ism ) of galaxies in the early universe is a cornerstone of modern galaxy evolution studies .
galaxies at early epochs show significantly elevated gas fractions relative to their local analogues @xcite , and it is these massive gas reservoirs that drive the enhanced star formation rates characteristic of the high-@xmath11 universe ( i.e. , @xcite ; @xcite ; ) . a variety of techniques have been used to observe the gas reservoirs in distant galaxies .
traditionally , the detection of intergalactic molecular gas ( particularly at high-@xmath11 ) has relied on observations of various molecular emission lines of carbon monoxide ( @xmath6co ; @xcite ; @xcite ; @xcite ; @xcite ) ..
Please generate the next two sentences of the article | co exists in the centres of molecular clouds , and with the aid of a co - to - h@xmath7 conversion factor observations of the co line luminosity can be converted into a mass of molecular gas .
this conversion is non - trivial however , with the abundance of co relative to h@xmath7 varying as a function of ism metallicity ( increased metal abundance results in larger quantities of dust to protect co from photodissociation ) and even galactic behaviour ( in merging systems the star - forming ism no longer consists of discrete molecular clouds , making co a more efficient tracer of molecular gas ) . |
7,945 | Suppose that you have an abstract for a scientific paper: a unified @xmath0-criterion for heat devices ( including heat engines and refrigerators ) which is defined as the product of the energy conversion efficiency and the heat absorbed per unit time by the working substance [ de toms _ et al _ 2012 _ phys .
rev .
e _ * 85 * 010104(r ) ] is optimized for tight - coupling heat engines and refrigerators operating between two heat baths at temperatures @xmath1 and @xmath2 . by taking a new convention on the thermodynamic flux related to the heat transfer between two baths
, we find that for a refrigerator tightly and symmetrically coupled with two heat baths , the coefficient of performance ( i.e. , the energy conversion efficiency of refrigerators ) at maximum @xmath0 asymptotically approaches to @xmath3 when the relative temperature difference between two heat baths @xmath4 is sufficiently small .
correspondingly , the efficiency at maximum @xmath0 ( equivalent to maximum power ) for a heat engine tightly and symmetrically coupled with two heat baths is proved to be @xmath5 up to the second order term of @xmath6 , which reverts to the universal efficiency at maximum power for tight - coupling heat engines operating between two heat baths at small temperature difference in the presence of left - right symmetry [ esposito _ et al _ 2009 _ phys .
rev .
lett . _ * 102 * 130602 ] . .
And you have already written the first three sentences of the full article: one of key topics in finite - time thermodynamics is the efficiency at maximum power for heat engines , which has been widely investigated by many researchers @xcite .
the most elegant result on this topic is @xmath7 , the efficiency at maximum power for endoreversible heat engines @xcite , where @xmath8 represents the carnot efficiency .
recently , the efficiencies at maximum power for stochastic heat engines @xcite , the feynman ratchet @xcite , and quantum dot engines@xcite were respectively achieved , and their expressions look quite different from @xmath9 ..
Please generate the next two sentences of the article | it is this difference that attracts researchers attention to the following two issues : one is the universal efficiency at maximum power for tight - coupling heat engines operating between two baths at small temperature difference @xcite ; the other is the global bounds of efficiency at maximum power for heat engines operating between two baths with arbitrary temperature difference @xcite . in particular
, van den broeck @xcite found that the universal efficiency at maximum power for tight - coupling heat engines is equal to @xmath10 up to the first order term of relative temperature difference between two baths . |
7,946 | Suppose that you have an abstract for a scientific paper: we analyze the results of a recent experiment with bosonic rubidium atoms harmonically confined in a quasi - two - dimensional geometry . in this experiment a well defined critical point was identified , which separates the high - temperature normal state characterized by a single component density distribution , and the low - temperature state characterized by a bimodal density distribution and the emergence of high - contrast interference between independent two - dimensional clouds .
we first show that this transition can not be explained in terms of conventional bose - einstein condensation of the trapped ideal bose gas . using the local density approximation
, we then combine the mean - field ( mf ) hartree - fock theory with the prediction for the berezinskii - kosterlitz - thouless transition in an infinite uniform system .
if the gas is treated as a strictly 2d system , the mf predictions for the spatial density profiles significantly deviate from those of a recent quantum monte - carlo ( qmc ) analysis .
however when the residual thermal excitation of the strongly confined degree of freedom is taken into account , an excellent agreement is reached between the mf and the qmc approaches .
for the interaction strength corresponding to the experiment , we predict a strong correction to the critical atom number with respect to the ideal gas theory ( factor @xmath0 ) .
a quantitative agreement between theory and experiment is reached concerning the critical atom number if the predicted density profiles are used for temperature calibration . .
And you have already written the first three sentences of the full article: as first noticed by peierls @xcite , collective physical phenomena in an environment with a reduced number of dimensions can be dramatically changed with respect to our experience in three dimensions .
the example of bose - einstein condensation in a uniform gas is a good illustration of the crucial role of dimensionality . in three dimensions ( 3d )
, condensation occurs at a finite temperature , and the phase of the macroscopic wave function exhibits long range order @xcite . in two dimensions ,.
Please generate the next two sentences of the article | such long range order is destroyed by thermal fluctuations at any finite temperature , both for an ideal and for an interacting bose gas @xcite . in presence of repulsive interactions between particles ,
a uniform 2d bose gas can nevertheless undergo a phase transition from a normal to a superfluid state at a finite critical temperature . |
7,947 | Suppose that you have an abstract for a scientific paper: collective motion in actively propelled particle systems is triggered on the very local scale by nucleation of coherently moving units consisting of just a handful of particles .
these units grow and merge over time , ending up in a long - range ordered , coherently - moving state .
so far , there exists no bottom - up understanding of how the microscopic dynamics and interactions between the constituents are related to the system s ordering instability . in this paper , we study a class of models for propelled colloids allowing an explicit treatment of the microscopic details of the collision process . specifically , the model equations are newtonian equations of motion with separate force terms for particles driving , dissipation and interaction forces . focusing on dilute particle systems , we analyze the binary scattering behavior for these models , and determine based on the microscopic dynamics the corresponding collision - rule " , _
i.e. _ , the mapping of pre - collisional velocities and impact parameter on post - collisional velocities . by studying binary scattering we also find that the considered models for active colloids share the same principle for parallel alignment : the first incoming particle ( with respect to the center of collision ) is aligned to the second particle as a result of the encounter .
this behavior is distinctively different to alignment in non - driven dissipative gases .
moreover , the obtained collision rule lends itself as a starting point to apply kinetic theory for propelled particle systems in order to determine the phase boundary to a long - range ordered , coherently - moving state .
the microscopic origin of the collision rule offers the opportunity to quantitatively scrutinize the predictions of kinetic theory for propelled particle systems through direct comparison with multi - particle simulations .
we identify local _ precursor _ correlations at the onset of collective motion to constitute the essential determinant for a qualitative and....
And you have already written the first three sentences of the full article: the emergence of collective motion in active systems composed of ( self-)propelled entities is a highly complex self - organization phenomenon @xcite .
examples include systems on vastly different length scales , ranging from micrometer - sized systems , made of biological constituents @xcite , over millimeter - sized vibrating hard granules @xcite , to large cooperative animal groups @xcite .
while all these systems share the capacity to form collective patterns , the precise mechanisms how they are formed and their degree of universality remain elusive . historically , generic agent - based models @xcite constitute the first theoretical approach aiming to understand the minimal ingredients necessary for the emergence of collective motion . in the vicsek model.
Please generate the next two sentences of the article | @xcite collective motion is thought to be a consequence of a generic competition between a local tendency of ferromagnetic parallel alignment " and noise . specifically , particle alignment is implemented as an update rule in the spirit of a cellular automaton : each particle aligns parallel to the average of all particles orientations within some defined finite neighborhood .
vicsek - like models have been instrumental in exploring the pattern forming capabilities of active systems @xcite . nevertheless , there are also drawbacks of such generic agent - based models . |
7,948 | Suppose that you have an abstract for a scientific paper: in this note , we present a novel method of extracting the couplings of a heavy particle to the standard model states . contrary to the usual discovery process which involves studying the on - shell production , we look at regions away from resonance to take advantage of the simple scaling of the cross - section with the couplings .
we illustrate the procedure with the example of a heavy quark . .
And you have already written the first three sentences of the full article: with the discovery of the higgs boson @xcite , the particle content of the standard model ( sm ) is well established .
the future aim of the large hadron collider ( lhc ) lies in uncovering clues for beyond the sm ( bsm ) physics - we expect these would manifest in the form of tev scale resonances . to make connection with theoretical models , we would need to measure both the mass of such a resonance and its coupling to the sm particles .
however , it is not straightforward to measure the couplings of a massive particle in a hadron collider environment , where the momenta of the interacting partons are not known for any single event ..
Please generate the next two sentences of the article | generally , it is easier to measure ratios of couplings or production rate times branching ratios ( brs ) . from these , in principle , it is possible to measure any coupling if the total decay width of the particle is also known .
however , since unlike the brs , measuring the width of a particle accurately can be quite difficult , this way of measuring couplings may lead to large uncertainties . in this note |
7,949 | Suppose that you have an abstract for a scientific paper: it is well known that the zee model induces small neutrino masses by radiative corrections , where the bi - maximal flavor mixing is possible .
we analyze the cosmological condition in order for the baryon asymmetry generated in the early universe not to be washed out in the zee model .
since the lepton number is violated explicitly in the zee model , the baryon asymmetry might be washed out through the sphaleron processes together with the lepton - number violating interactions . in this letter , we will show that the baryon asymmetry is _ not _ washed out , although it has been said that the zee model can not preserve the baryon asymmetry generated in the early universe .
this can be seen by considering an approximately conserved number , @xmath0 .
hep - ph/0108013 + dpnu-01 - 18 + ut-956 + .
And you have already written the first three sentences of the full article: recently the evidences of neutrino oscillations are strongly supported by both of the atmospheric @xcite and the solar neutrino experiments @xcite .
the former suggests an almost maximal lepton flavor mixing between the 2nd and the 3rd generations , while the favorable solution to the solar neutrino deficits is given by large mixing angle solution between the 1st and the 2nd generations ( lma , low or vo ) @xcite .
neutrino oscillation experiments indicate that the neutrinos have tiny but finite masses , with two mass squared differences @xmath1 . since the neutrino mass is much smaller than other quarks and leptons , the origin of the neutrino mass is expected to be different from that of others ..
Please generate the next two sentences of the article | the most popular mechanism to induce the small neutrino masses is the seesaw mechanism @xcite , which needs heavy right - handed neutrinos .
however , it is important to consider also other possible scenarios which can explain the small neutrino masses , especially low - energy extensions of the standard model . |
7,950 | Suppose that you have an abstract for a scientific paper: 1.0 cm 1.0 cm two - particle azimuthal correlations of high-@xmath0 hadrons can serve as a probe of interactions of partons with the dense medium produced in high - energy heavy - ion collisions .
first na49 results on such correlations are presented for central and mid - central pb+pb collisions at 158@xmath1 gev beam energy , for different centrality bins and charge combinations of trigger and associate particles .
these results feature a flattened away - side peak in the most central collisions , which is consistent with expectations of the medium - interaction scenario .
a comparison with ceres pb+au results at the same energy , as well as with phenix au+au results at the top rhic energy , is provided . .
And you have already written the first three sentences of the full article: it is believed that one of the signatures of a hot , dense medium expected to appear in most central high - energy collisions of heavy ions , will be modification of properties of jets highly collimated streams of particles , originating from hard scattering of partons and therefore produced early in a collision as a result of their interaction with that medium @xcite .
unfortunately , direct reconstruction of jets in the presence of a large background typical of such events is an extremely challenging task .
one possible answer to this problem is studying two - particle azimuthal correlations , which allow one to extract the jet signal from the soft background by taking advantage of the fact jet particles are strongly correlated in azimuth . in recent years.
Please generate the next two sentences of the article | rhic experiments have made this approach highly successful by not only observing the expected signatures , but also providing , through further investigations , evidence which has led to a major change of expectations regarding properties of the hot medium ( the `` perfect liquid '' description ; see _ e.g. _ @xcite ) . however , until recently ( @xcite ) no analyses of this sort were performed in the energy range of the cern sps .
the na49 detector is a large - acceptance spectrometer dedicated to the study of hadron production in fixed - target nucleon - nucleon , nucleon - nucleus and nucleus - nucleus collisions at a wide range of energies offered by the cern sps . during its eight years of running |
7,951 | Suppose that you have an abstract for a scientific paper: a transiting planet exhibits sinusoidal transit - time - variations ( ttvs ) if perturbed by a companion near a mean - motion - resonance ( mmr ) .
we search for sinusoidal ttvs in more than 2600 kepler candidates , using the publicly available kepler light - curves ( q0-q12 ) .
we find that the ttv fractions rise strikingly with the transit multiplicity .
systems where four or more planets transit enjoy four roughly five times higher ttv fraction than those where a single planet transits , and about twice higher than those for doubles and triples .
in contrast , models in which all transiting planets arise from similar dynamical configurations predict comparable ttv fractions among these different systems .
one simple explanation for our results is that there are at least two different classes of kepler systems , one closely packed and one more sparsely populated . .
And you have already written the first three sentences of the full article: since the launch in march 2009 , the _ kepler _ mission has discovered a few thousand planetary candidates , called kepler objects of interests ( kois ) , by detecting the flux deficit as a planet transits in front of its star @xcite . while some of the stars are observed to have one transiting planet ( called tranet from now on , following * ? ? ?
* ) , others show up to 6 @xcite . a natural question to ask is , do all of these systems share the same intrinsic orbital structures ? for observing transiting planets ,
the two most relevant orbital parameters are the dispersion in orbital inclinations , and the typical spacing between adjacent planets ..
Please generate the next two sentences of the article | a number of groups have studied the inclination dispersion of kepler planets and reached the common conclusion that this must be small and is of order a few degrees @xcite .
however , it has been pointed out that models with a single inclination dispersion falls short in explaining the number of single tranets relative to higher multiples , by a factor of three or more @xcite . |
7,952 | Suppose that you have an abstract for a scientific paper: magnetic fields play an important role in almost all astrophysical phenomena including star formation .
but due to the difficulty in analytic modeling and observation , magnetic fields are still poorly studied and numerical simulation has become a major tool .
we have implemented a cosmological magnetohydrodynamics package for enzo which is an amr hydrodynamics code designed to simulate structure formation .
we use the tvd solver developed by s. li as the base solver .
in addition , we employ the constrained transport ( ct ) algorithm as described by d. balsara . for interpolation magnetic fields to fine grids we used a divergence free quadratic reconstruction , also described by balsara .
we present results from several test problems including mhd caustics , mhd pancake and galaxy cluster formation with magnetic fields .
we also discuss possible applications of our amr mhd code to first star research .
address = department of physics and cass , university of california , san diego , san diego , ca , altaddress = theoretical astrophysics , los alamos national laboratory , los alamos , nm address = department of physics and cass , university of california , san diego , san diego , ca address = department of physics and cass , university of california , san diego , san diego , ca address = mathematical modeling and analysis , los alamos national laboratory , los alamos , nm address = theoretical astrophysics , los alamos national laboratory , los alamos , nm .
And you have already written the first three sentences of the full article: adaptive mesh refinement(amr ) cosmological hydrodynamics simulations play an important role in the study of structure formation of different scales from galaxy clusters to first stars in the past ten years .
its ability to achieve very high resolution in large scale simulations with relatively small computer resources has helped us to understand the first stars formed in our universe .
the possible effects of magnetic fields have been largely ignored ..
Please generate the next two sentences of the article | it is well established that magnetic fields are present on different scales , from intracluster medium to interstellar medium .
the origin and evolution of these magnetic fields and their role on the structure formation are still unclear . |
7,953 | Suppose that you have an abstract for a scientific paper: we examined offsets between hii regions and molecular clouds belonging to spiral arms of a late type spiral galaxy ngc 4254 ( m99 ) .
we used a high resolution @xmath0co ( @xmath1=1 - 0 ) image obtained by nobeyama millimeter array ( nma ) and an h@xmath2 image .
we derived angular offsets ( @xmath3 ) in the galactic disk , and found that these offsets show a linear dependence on the angular rotation velocity of gas ( @xmath4 ) .
this linear relation can be expressed by an equation : @xmath5 , where @xmath6 and @xmath7 are constant . here
, @xmath6 corresponds to the pattern speed of spiral arms and @xmath7 is interpreted as the timescale between the peak compression of the molecular gas in spiral arms and the peak of massive star formation .
we may thus determine @xmath6 and @xmath7 simultaneously by fitting a line to our @xmath8 plot , if we assumed they are constant . from our plot , we obtained @xmath9 yr and @xmath10 , which are consistent with previous studies .
we suggest that this @xmath8 plot can be a new tool to determine the pattern speed and the typical timescale needed for star formations . .
And you have already written the first three sentences of the full article: pattern speed ( @xmath6 ) is defined as an angular rotation velocity of spiral pattern . according to the spiral density wave theory @xcite
, @xmath6 determines the location and even the existence of resonances , which would greatly affect the morphology and kinematics of a galaxy .
the results of numerical simulations also show the large dependence of spiral structure on @xmath6 @xcite . despite its importance on the study of galaxies.
Please generate the next two sentences of the article | , it can not be determined directly from observations , since the pattern structure is not a material but a density wave propagating through the disk .
several methods have been proposed to date for the determination of pattern speed . |
7,954 | Suppose that you have an abstract for a scientific paper: in this paper , we give a numerical analysis for the transmission eigenvalue problem by the finite element method .
a type of multilevel correction method is proposed to solve the transmission eigenvalue problem .
the multilevel correction method can transform the transmission eigenvalue solving in the finest finite element space to a sequence of linear problems and some transmission eigenvalue solving in a very low dimensional spaces . since the main computational work is to solve the sequence of linear problems , the multilevel correction method improves the overfull efficiency of the transmission eigenvalue solving .
some numerical examples are provided to validate the theoretical results and the efficiency of the proposed numerical scheme .
transmission eigenvalue problem , finite element method , error estimates , multilevel correction method 65n30 , 65n25 , 65l15 , 65b99 . .
And you have already written the first three sentences of the full article: recently , many researchers are interested in the transmission eigenvalue problem @xcite .
the transmission eigenvalue problem arises in the study of the inverse scattering for inhomogeneous media which not only has theoretical importance @xcite , but also can be used to estimate the properties of the scattering material @xcite since they can be determined from the scattering data . in the past few years
, significant progress of the existence of transmission eigenvalues and applications has been made ..
Please generate the next two sentences of the article | we refer the readers to the recent papers @xcite . meanwhile , there are also many papers to give the numerical treatment for the transmission eigenvalue problem and the associated interior transmission problem @xcite .
but there are few papers providing the corresponding theoretical analysis for their numerical methods due to the difficulty that the problem is neither elliptic nor self - adjoint . |
7,955 | Suppose that you have an abstract for a scientific paper: we consider a biased molecular junction subjected to external time - dependent electromagnetic field .
the field for two typical junction geometries ( bowtie antennas and metal nanospheres ) is calculated within finite - difference time - domain technique .
time - dependent transport and optical response of the junctions is calculated within non - equilibrium green s function approach expressed in a form convenient for description of multi - level systems .
we present numerical results for a two - level ( homo - lumo ) model , and discuss influence of localized surface plasmon polariton modes on transport . .
And you have already written the first three sentences of the full article: optical properties of structures composed of noble metals have long been attracting a considerable attention due to unique features of such systems in the visible spectrum.@xcite recent advances in fabrication techniques@xcite along with a tremendous progress in laser technologies opened new venues for application of plasmonic materials in biology,@xcite integrated optics,@xcite nanoscale imagining,@xcite and single molecule manipulation.@xcite physics of surface plasmon phenomenon is relatively simple and has long been studied.@xcite in brief , coherent oscillations of conductive electrons in a skin - layer of metal known as plasmons are capable of producing strong local electromagnetic ( em ) fields in the near - field region .
it has been reported that such `` hot '' spots can be localized within @xmath0 nm or less .
this along with a great sensitivity to initial conditions and geometry makes plasmonic structures so attractable for atom / molecule manipulations . a natural combination of nanoplasmonics and molecular response to the generated field started to appear as molecular nanopolaritonics,@xcite which studies molecular influence on field propagation , and as a tool for developing molecular switches.@xcite the latter utilizes nonadiabatic alignment of a molecule on semiconductor surface under a tip of scanning tunneling microscope ..
Please generate the next two sentences of the article | recent developments in experimental techniques capable of measuring optical response of current - carrying molecular junctions@xcite lead to theoretical formulations suitable for simultaneous description of both transport and optical properties of molecular devices.@xcite while experimental data are measured in real time , theoretical description of both transport and optical response so far has mostly been focused on a steady - state description .
time - dependent transport usually is treated either within kinetic theory@xcite or within time - dependent density functional approach.@xcite the former generally misses broadening of molecular states due to coupling to macroscopic contacts@xcite and information on coherence,@xcite although interesting generalizations started to appear.@xcite limitations of the latter are due to absence of developed pseudopotentials and fundamental necessity to treat finite ( closed ) systems ( see e.g. ref . for discussion ) . |
7,956 | Suppose that you have an abstract for a scientific paper: a semi - riemannian manifold is said to satisfy @xmath0 ( or @xmath1 ) if spacelike sectional curvatures are @xmath2 and timelike ones are @xmath3 ( or the reverse ) .
such spaces are abundant , as warped product constructions show ; they include , in particular , big bang robertson - walker spaces . by stability , there are many non - warped product examples .
we prove the equivalence of this type of curvature bound with local triangle comparisons on the signed lengths of geodesics . specifically , @xmath0 if and only if locally the signed length of the geodesic between two points on any geodesic triangle is at least that for the corresponding points of its model triangle in the riemannian , lorentz or anti - riemannian plane of curvature @xmath4 ( and the reverse for @xmath1 ) .
the proof is by comparison of solutions of matrix riccati equations for a modified shape operator that is smoothly defined along reparametrized geodesics ( including null geodesics ) radiating from a point .
also proved are semi - riemannian analogues to the three basic alexandrov triangle lemmas , namely , the realizability , hinge and straightening lemmas .
these analogues are intuitively surprising , both in one of the quantities considered , and also in the fact that monotonicity statements persist even though the model space may change .
finally , the algebraic meaning of these curvature bounds is elucidated , for example by relating them to a curvature function on null sections . .
And you have already written the first three sentences of the full article: [ sec : intro ] alexandrov spaces are geodesic metric spaces with curvature bounds in the sense of local triangle comparisons .
specifically , let @xmath5 denote the simply connected 2-dimensional riemannian space form of constant curvature @xmath4 . for curvature bounded below ( cbb ) by @xmath4
, the distance between any two points of a geodesic triangle is required to be @xmath6 the distance between the corresponding points on the `` model '' triangle with the same sidelengths in @xmath5.
Please generate the next two sentences of the article | . for curvature bounded above ( cba ) , substitute `` @xmath7 '' .
examples of alexandrov spaces include riemannian manifolds with sectional curvature @xmath2 or @xmath3 . |
7,957 | Suppose that you have an abstract for a scientific paper: closed flrw universe of three - dimensional einstein gravity with positive cosmological constant is investigated by using the cillins - williams formalism in regge calculus .
spherical cauchy surface is replaced with regular polyhedrons .
the regge equations are reduced to differential equations in continuum time limit . numerical solution to the regge equations well approximate the continuum flrw universe during the era of small edge length .
the deviation from the continuum solution becomes larger and larger as time goes to infinity . unlike the continuum the expansion speed of universe approaches to a constant in the infinite future . to remedy the shortcoming of the model universe
we introduce geodesic domes . regarding the geodesic domes as pseudo - regular polyhedorons with fractional schlfli symbol
, we can describe the behaviors of the universe more acurately in regge calculus .
it is shown that the scale factor of the continuum theory can be reproduced from the regge equations in the infinite frequency limit . *
expanding polyhedral universe in regge calculus * ren tsuda@xmath0 and takanori fujiwara@xmath1 _ @xmath0 graduate school of science and engineering , ibaraki university , mito 310 - 8512 , japan + @xmath1 department of physics , ibaraki university , mito 310 - 8512 , japan _ .
And you have already written the first three sentences of the full article: regge calculus was proposed to formulate einstein s general relativity on piecewise linear manifolds @xcite .
it provides coordinate - free lattice formulation of gravitation and has been used in investigations of classical as well as quamtum gravity .
as is the case of qcd , lattice theoretical approach provides a powerfull framework in nonperturbative studies of quantum gravity @xcite ..
Please generate the next two sentences of the article | however , before moving to detailed quantum study , it is desired to investigate the formalism at the classical level .
any lattice regularized theory should reproduce basic results of corresponding continuum theory . |
7,958 | Suppose that you have an abstract for a scientific paper: in 2004 , carter , elhamdadi and saito defined a homology theory for set - theoretic yang - baxter operators(we will call it the algebraic " version in this article ) . in 2012 ,
przytycki defined another homology theory for pre - yang - baxter operators which has a nice graphic visualization(we will call it the graphic " version in this article ) .
we show that they are equivalent .
the graphic " homology is also defined for pre - yang - baxter operators , and we give some examples of it s one - term and two - term homologies . in the two - term case , we have found torsion in homology of yang - baxter operator that yields the jones polynomial . .
And you have already written the first three sentences of the full article: the yang - baxter equation was introduced independently by c.n . yang(1967)@xcite and r.j .
it is well known that a certain solution of yang - baxter equation give rise to the jones polynomial @xcite . in 2004 ,
carter , elhamdadi and saito defined a ( co)homology theory for set - theoretic yang - baxter operators , from which they gave a way to generate link invariants , cocycle invariants@xcite . in 2012 , przytycki gave a graphical definition of homology for a pre - yang - baxter operator @xcite ..
Please generate the next two sentences of the article | we provide the definitions of two homology theories for set - theoretic yang - baxter operators in section 2 and show their equivalence in section 3 . in section 4 ,
we give definitions of one - term and two - term homology of pre - yang - baxter operators , and show examples , in particular , we find torsion in two - term homology of yang - baxter operator that yields the jones polynomial . we start from basic definitions . [ definition 1.1 ] |
7,959 | Suppose that you have an abstract for a scientific paper: using simulated signals and measured noise with the explorer and nautilus detectors we find the efficiency of signal detection and the signal arrival time dispersion versus the signal - to - noise ratio . .
And you have already written the first three sentences of the full article: there are today five detectors of gravitational waves ( gw ) in operation @xcite , all of them of the resonant type .
it is thus important to study in detail the problem of the coincidence search . in the past , after the initial works of weber , three papers on coincidence search have been published @xcite .
these coincidence search was made under two hidden assumptions : + a)the signal - to - noise ratio ( snr ) was considered to be very large , + b)the event time was considered to be equal to the signal time . + since we expect very tiny signals , the study of the problem when dealing with small snrs is fundamental ..
Please generate the next two sentences of the article | this is our object here using simulated signals but with real noise measured with the explorer and nautilus detectors .
in order to clarify the distinction between @xmath0 and @xmath1 let us recall how an @xmath1 is defined . |
7,960 | Suppose that you have an abstract for a scientific paper: + this paper is the third in a series of papers working towards the construction of a realistic , evolving , non - linear force - free coronal field model for the solar magnetic carpet . here , we present preliminary results of 3d time - dependent simulations of the small - scale coronal field of the magnetic carpet .
four simulations are considered , each with the same evolving photospheric boundary condition : a 48 hr time series of synthetic magnetograms produced from the model of .
three simulations include a uniform , overlying coronal magnetic field of differing strength , the fourth simulation includes no overlying field .
the build - up , storage and dissipation of magnetic energy within the simulations is studied . in particular , we study their dependence upon the evolution of the photospheric magnetic field and the strength of the overlying coronal field .
we also consider where energy is stored and dissipated within the coronal field .
the free magnetic energy built up is found to be more than sufficient to power small - scale , transient phenomena such as nanoflares and x - ray bright points , with the bulk of the free energy found to be stored low down , between @xmath0 mm .
the energy dissipated is presently found to be too small to account for the heating of the entire quiet sun corona . however , the form and location of energy dissipation regions are in qualitative agreement with what is observed on small scales on the sun .
future mhd modelling using the same synthetic magnetograms may lead to a higher energy release . .
And you have already written the first three sentences of the full article: the small - scale photospheric magnetic field of the quiet sun , the _ magnetic carpet _ , is complex and constantly evolving .
this evolution is due to underlying photospheric flows produced by convection on many scales ( _ e.g. _ granulation and supergranulation , , , , ) and the flux evolution processes of emergence , cancellation , coalescence and fragmentation .
small - scale magnetic features classified as ephemeral regions @xcite , internetwork features @xcite and network features @xcite continually interact with one another , resulting in a photospheric recycle time of just @xmath1.
Please generate the next two sentences of the article | hr ( hours ) @xcite .
this is the time taken for all flux within the quiet sun photosphere to be replaced . since magnetic fields from the magnetic carpet |
7,961 | Suppose that you have an abstract for a scientific paper: we introduce _ dark mediator dark matter _ ( dmdm ) where the dark and visible sectors are connected by at least one light mediator @xmath0 carrying the same dark charge that stabilizes dm .
@xmath0 is coupled to the standard model via an operator @xmath1 , and to dark matter via a yukawa coupling @xmath2 .
direct detection is realized as the @xmath3 process @xmath4 at tree - level for @xmath5 and small yukawa coupling , or alternatively as a loop - induced @xmath6 process @xmath7 .
we explore the direct - detection consequences of this scenario and find that a heavy @xmath8 dmdm candidate fakes different @xmath9 standard wimps in different experiments .
large portions of the dmdm parameter space are detectable above the irreducible neutrino background and not yet excluded by any bounds .
interestingly , for the @xmath10 range leading to novel direct detection phenomenology , dmdm is also a form of self - interacting dark matter ( sidm ) , which resolves inconsistencies between dwarf galaxy observations and numerical simulations . .
And you have already written the first three sentences of the full article: in this letter , we present _ dark mediator dark matter _ ( dmdm ) to address two important gaps in the dm literature : exploring mediators with dark charge , and non - standard interaction topologies for scattering off nuclei . additional details and constraints will be explored in a companion paper @xcite . the existence of dark matter is firmly established by many astrophysical and cosmological observations @xcite , but its mass and coupling to the standard model ( sm ) particles are still unknown . weakly interacting massive particles ( wimps ) are
the most popular dm candidates since they arise in many theories beyond the sm , including supersymmetry , and may naturally give the correct relic abundance @xcite .
however , improved experimental constraints from collider searches , indirect detection and direct detection @xcite begin to set tight limits ( with some conflicting signal hints ) on the standard wimp scenario with a contact interaction to quarks ..
Please generate the next two sentences of the article | this makes it necessary to look for a more complete set of dm models which are theoretically motivated while giving unique experimental signatures .
process at tree - level . |
7,962 | Suppose that you have an abstract for a scientific paper: a method for simulation of elastoplastic solids in multibody systems with nonsmooth and multidomain dynamics is developed .
the solid is discretised into pseudo - particles using the meshfree moving least squares method .
the particles carry strain and stress tensor variables that are mapped to deformation constraints and constraint forces .
the discretised solid model thus fit a unified framework for nonsmooth multidomain dynamics for realtime simulations including strong coupling of rigid multibodies with complex kinematic constraints such as articulation joints , unilateral contacts with dry friction , drivelines and hydraulics .
the nonsmooth formulation allow for impulses , due to impacts for instance , to propagate instantly between the rigid multibody and the solid .
plasticity is introduced through an associative perfectly plastic modified drucker - prager model .
the elastic and plastic dynamics is verified for simple test systems and the capability of simulating tracked terrain vehicles driving on a deformable terrain is demonstrated . .
And you have already written the first three sentences of the full article: we address the modeling and simulation of elastoplastic solids in multidomain environments including also mechatronic multibody systems with nonsmooth dynamics , such as vehicles , robots and processing machinery .
fast multidomain simulation is useful for concept design exploration , development of control algorithms and for interactive realtime simulators , e.g. , for operator training , human - machine interaction studies and hardware - in - the - loop testing .
realizing such simulators require integrating many subsystems of different types and complexity into a single multidomain dynamics model ..
Please generate the next two sentences of the article | if the subsystems are loosely coupled , the full system simulation can be realised by means of co - simulation @xcite , but this is not the general case .
for the sake of computational performance , coarse grain models are often used , with rigid and flexible bodies coupled by kinematic constraints for modeling of joints and differential algebraic equation ( dae ) models for electronics , hydraulics and powertrain dynamics @xcite . at coarse timescales |
7,963 | Suppose that you have an abstract for a scientific paper: particularly in genomics , but also in other fields , it has become commonplace to undertake highly multiple student s @xmath0-tests based on relatively small sample sizes . the literature on this topic is continually expanding , but the main approaches used to control the family - wise error rate and false discovery rate are still based on the assumption that the tests are independent .
the independence condition is known to be false at the level of the joint distributions of the test statistics , but that does not necessarily mean , for the small significance levels involved in highly multiple hypothesis testing , that the assumption leads to major errors . in this paper , we give conditions under which the assumption of independence is valid .
specifically , we derive a strong approximation that closely links the level exceedences of a dependent `` studentized process '' to those of a process of independent random variables . via this connection
, it can be seen that in high - dimensional , low sample - size cases , provided the sample size diverges faster than the logarithm of the number of tests , the assumption of independent @xmath0-tests is often justified . .
And you have already written the first three sentences of the full article: today it is commonplace to undertake highly multiple hypothesis testing , generally in genomics and very often using tests based on student s @xmath0-statistic ; see , for example , benjamini and yekutieli ( @xcite ) , efron and tibshirani ( @xcite ) , cui and churchill ( @xcite ) , amaratunga and cabrera ( @xcite ) , page 114 , scheid and spang ( @xcite ) , shaffer ( @xcite ) , fox and dimmic ( @xcite ) , hu and willsky ( @xcite ) , qiu and yakovlev ( @xcite ) , efron ( @xcite ) , liu and hwang ( @xcite ) and van de wiel and kim ( @xcite ) .
this popularity of multiple @xmath0-testing also extends to other fields ( e.g. , pawluk - koc _ et al . _
( @xcite ) ) ..
Please generate the next two sentences of the article | the principal methods used to control the family - wise error rate and false discovery rate are founded on the assumption of independence among tests .
alternative approaches are generally based either on bonferroni bounds , which are unsatisfactory for a variety of reasons ( see , e.g. , perneger ( @xcite ) ) , or on the hope that , despite ample evidence of non - independence in terms of correlation analysis , independence can be assumed in practice . |
7,964 | Suppose that you have an abstract for a scientific paper: origin of recently discovered reversed ( opposite sign ) dark resonances was explained theoretically and verified experimentally .
it is shown that the reason for these resonances is a specific optical pumping of ground state level in a transition when ground state angular momentum is smaller than the excited state momentum .
[ theorem]acknowledgement [ theorem]algorithm [ theorem]axiom [ theorem]claim [ theorem]conclusion [ theorem]condition [ theorem]conjecture [ theorem]corollary [ theorem]criterion [ theorem]definition [ theorem]example [ theorem]exercise [ theorem]lemma [ theorem]notation [ theorem]problem [ theorem]proposition [ theorem]remark [ theorem]solution [ theorem]summary .
And you have already written the first three sentences of the full article: coherent population trapping was discovered in the interaction of sodium atoms with a laser field in 1976 .
@xcite . due to this effect a substantial part of population , because of destructive quantum interference between different excitation pathways , is trapped in a coherent superposition of ground state sublevels dark states . with a coherent population trapping
are associated dark resonances when due to this effect absorption and as a result fluorescence from atoms decreases , but intensity of the transmitted light increases when part of the atomic population is trapped in dark states ..
Please generate the next two sentences of the article | if in addition to the optical excitation an external magnetic field is applied , it can destroy coherence between ground state sublevels and return trapped population into absorbing states and , as a result , increase absorption and fluorescence , but decrease a transmitted light .
a review of applications of dark resonances was published some years ago by arimondo @xcite . |
7,965 | Suppose that you have an abstract for a scientific paper: a theory of coherent multiple andreev reflections ( mar ) is developed for superconductor - normal metal - superconductor ( sns ) interferometers .
we consider a y - shape normal electron beam splitter connecting two superconducting reservoirs , where the two connection points to the same superconductor can have different phase .
the current is calculated in the quantum transport regime as a function of applied voltage and phase difference , @xmath0 .
mar in interferometers incorporates two features : interference in the arms of the splitter , and interplay with andreev resonances .
the latter feature yields enhancement of the subgap current and current peaks with phase - dependent positions and magnitudes .
the interference effect leads to suppression of the subgap current and complete disappearance of the current peaks at @xmath1 .
the excess current at large voltage decreases and changes sign with increasing phase difference . .
And you have already written the first three sentences of the full article: mesoscopic circuits with multiterminal electron wave guides have interesting and useful physical properties .
figure [ fig : setup ] shows an example of a circuit where a y - branch wave guide acts as a coherent beam splitter for electrons injected from a normal or superconducting reservoir .
such a circuit with normal electron reservoirs ( nyn ) has been first suggested to test statistical properties of the fermi electrons by measuring current - current correlations in the arms of the splitter.@xcite this correlation is negative for the case of fermi statistics , which was indeed observed in the experiment.@xcite however , the correlations may change the sign and become positive ( similar to the case of bose particles ) when the electrons are injected from a superconducting reservoir ( nys).@xcite this effect is related to the cooper pairing in the superconductor ..
Please generate the next two sentences of the article | another kind of interference effect , namely a phase dependent conductance , has been predicted@xcite for a circuit geometry ( syn ) where the arms of the electron beam splitter are connected to a superconductor . in this case , the electrons undergo andreev reflection from the ns interfaces@xcite , picking up the superconducting phase at the connection points . the phase difference at the connection points
is created by a supercurrent flowing along the surface of superconducting electrode , e.g. due to a presence of a magnetic field ( see fig . [ |
7,966 | Suppose that you have an abstract for a scientific paper: we present the first detailed imaging polarization observations of six smc and six lmc clusters , known to have large populations of b - type stars which exhibit excess h@xmath0 emission , to constrain the evolutionary status of these stars and hence better establish links between the onset of disk formation in classical be stars and cluster age and/or metallicity .
we parameterize the interstellar polarization ( isp ) along the lines of sight to these twelve clusters , thereby providing a diagnostic of the fundamental properties of the dust which characterizes their localized interstellar medium .
we determine that the isp associated with the smc cluster ngc 330 is characterized by a modified serkowski law with @xmath1 @xmath24500 , indicating the presence of smaller than average dust grains .
furthermore , the morphology of the isp associated with the lmc cluster ngc 2100 suggests that its interstellar environment is characterized by a complex magnetic field .
removing this interstellar polarization component from our data isolates the presence of any intrinsic polarization ; the wavelength dependence of this intrinsic polarization provides a diagnostic of the dominant and any secondary polarigenic agents present , enabling us to discriminate pure gas disk systems , i.e. classical be stars , from composite gas plus dust disk systems , i.e. herbig ae / be or b[e ] stars .
our _ intrinsic _ polarization results , along with available near - ir color information , strongly supports the suggestion of wisniewski et al .
that classical be stars are present in clusters of age 5 - 8 myr , and contradict assertions that the be phenomenon only develops in the second half of a b star s main sequence lifetime , i.e. no earlier than 10 myr .
our data imply that a significant number of b - type stars must emerge onto the zero - age - main - sequence rotating at near - critical rotation rates , although we can not rule out the possibility that these data instead reveal the presence of a sub - group of....
And you have already written the first three sentences of the full article: while the rapid rotation ( v@xmath3/v@xmath4 @xmath270 - 80% of their critical velocity ; @xcite ) of classical be stars has long been speculated to be the fundamental source driving the production of their geometrically thin circumstellar disks @xcite , recent photometric surveys @xcite have suggested secondary mechanisms might contribute to the observed phenomenon .
specifically , @xcite and @xcite found that the frequency of the be phenomenon seems to peak in clusters with a main sequence turn - off of b1-b2 , leading to the suggestion that the be phenomenon is enhanced with evolutionary age .
several recent observational studies @xcite have also suggested that the be phenomenon may be more prevalent in low metallicity environments , based on comparisons of the fractional be populations of galactic , lmc , and smc clusters . in @xcite ( hereafter wb06 ).
Please generate the next two sentences of the article | , we used a simple 2-color diagram ( 2-cd ) technique to identify the fractional candidate be population of numerous large magellanic cloud ( lmc ) , small magellanic cloud ( smc ) , and galactic clusters in an effort to improve the statistical database which has been used to link classical be disk formation with evolutionary age and/or metallicity .
wb06 found evidence that the be phenomenon develops much earlier than previously predicted by theory @xcite , i.e before the mid - point main sequence lifetime ; furthermore , they found evidence of an additional enhancement in the fractional be content of clusters with evolutionary age . |
7,967 | Suppose that you have an abstract for a scientific paper: a way to pose the entropic uncertainty principle for trace - preserving super - operators is presented .
it is based on the notion of extremal unraveling of a super - operator . for given input state , different effects of each unraveling result in some probability distribution at the output . as it is shown , all tsallis entropies of positive order as well as some of rnyi s entropies of this distribution are minimized by the same unraveling of a super - operator .
entropic relations between a state ensemble and the generated density matrix are revisited in terms of both the adopted measures .
using riesz s theorem , we obtain two uncertainty relations for any pair of generalized resolutions of the identity in terms of the rnyi and tsallis entropies .
the inequality with rnyi s entropies is an improvement of the previous one , whereas the inequality with tsallis entropies is a new relation of a general form .
the latter formulation is explicitly shown for a pair of complementary observables in a @xmath0-level system and for the angle and the angular momentum .
the derived general relations are immediately applied to extremal unravelings of two super - operators . .
And you have already written the first three sentences of the full article: since the famous heisenberg s paper @xcite had been published , uncertainty relations are the subject of long researches @xcite .
a new interest was stimulated by recent advances in quantum information processing .
there are two well - known approaches to formulating the uncertainty principle ..
Please generate the next two sentences of the article | the first was initiated by robertson @xcite who showed that a product of the standard deviations of two observables is bounded from below .
here we may run across some disputable topics such as the number - phase case @xcite . |
7,968 | Suppose that you have an abstract for a scientific paper: recently , allen et al . measured a tight correlation between the bondi accretion rates and jet powers of the nuclei of nearby x - ray luminous elliptical galaxies .
we employ two models of jet powering to understand the above correlation and derive constraints on the spin and accretion rate of the central black holes .
the first is the blandford - znajek model , in which the spin energy of the hole is extracted as jet power ; the second model is an hybrid version of the blandford - payne and blandford - znajek processes , in which the outflow is generated in the inner parts of the accretion disk .
we assume advection - dominated accretion flows ( adaf ) and account for general relativistic effects .
our modelling implies that for typical values of the disk viscosity parameter @xmath0 the tight correlation implies the narrow range of spins @xmath1 and accretion rates @xmath2 .
our results provide support for the `` spin paradigm '' scenario and suggest that the central black holes in the cores of clusters of galaxies must be rapidly rotating in order to drive radio jets powerful enough to quench the cooling flows . .
And you have already written the first three sentences of the full article: recently , @xcite ( hereafter a06 ) measured a tight correlation between the bondi accretion rates @xmath3 and jet powers @xmath4 of the nuclei of nine nearby , x - ray luminous elliptical galaxies using _ chandra _ x - ray observations .
it is imperative to understand how this correlation is established and what constraints on the properties of the central black holes can be derived from it .
this is the goal of the present work ..
Please generate the next two sentences of the article | the origin of jets is likely to be related to the spin of the central black hole ( e.g. , @xcite ) . with this in mind , we employ two physical models of jet production which relate the spin @xmath5 ( @xmath6 ) and accretion rate @xmath7 onto the black hole to the observed jet power in order to understand the empirical correlation of a06 : the blandford - znajek ( bz ) model ( e.g. , @xcite ) , in which magnetic fields threading the hole extract its rotational energy and drive the jet ; and a `` hybrid model '' @xcite which combines the blandford - payne and bz mechanisms , in which the fields tap energy from the accretion flow and the spinning hole .
we assume that in the nuclei of the observed elliptical galaxies the accretion flow around the black hole is advection - dominated ( advection - dominated accretion flows , hereafter adaf , e.g. , @xcite , see also contribution of f. yuan in this volume ) . |
7,969 | Suppose that you have an abstract for a scientific paper: high resolution long - slit spectra obtained with the phoenix spectrograph on gemini south provide our most accurate probe of the three dimensional structure of the homunculus nebula around @xmath0 carinae .
the new near - infrared spectra dramatically confirm the double - shell structure inferred previously from thermal dust emission , resolving the nebula into a very thin outer shell seen in h@xmath1 @xmath221218 , and a warmer , thicker inner layer seen in [ fe ii ] @xmath216435 .
the remarkably thin and uniform h@xmath1 skin has @xmath3r / r of only a few per cent at the poles , hinting that the most important mass loss during the 19th century eruption may have had a very short duration of @xmath45 yr .
h@xmath1 emission traces the majority of the more than 10 m@xmath5 of material in the nebula , and has an average density of order @xmath610@xmath7 @xmath8 .
this emission , in turn , yields our first definitive picture of the exact shape of the nebula , plus a distance of 2350@xmath950 pc and an inclination angle of @xmath1041 ( the polar axis is tilted 49 from the plane of the sky ) .
the distribution of the h@xmath1 emission provides the first measure of the latitude dependence of the speed , mass loss , and kinetic energy associated with @xmath0 car s 19th century explosion .
almost 75% of the total mass and more than 90% of the kinetic energy in the ejecta were released at high latitudes between 45 and the polar axis .
this rules out a model for the bipolar shape wherein an otherwise spherical explosion was pinched at the waist by a circumstellar torus .
also , the ejecta could not have been deflected toward polar trajectories by a companion star , since the kinetic energy of the polar ejecta is greater than the binding energy of the putative binary system .
instead , most of the mass appears to have been directed poleward by the explosion itself or the star failed to launch material from low latitudes , which would have important consequences for the angular momentum....
And you have already written the first three sentences of the full article: the homunculus nebula around @xmath0 carinae is composed of a striking pair of lumpy bipolar lobes divided by a ragged equatorial skirt ( morse et al . 1998 ; duschl et al . 1995 ;
smith et al . 2000 ; smith & gehrz 2000 ) .
it is primarily a reflection nebula at uv , visual , and near - ir wavelengths , since it is highly polarized ( thackeray 1956b , 1961 ; visvanathan 1967 ; meaburn et al . 1993 ; schulte - ladbeck et al.1999 ) , and because stellar wind emission lines are seen reflected by the nebula ( allen & hillier 1991 ; davidson et al . 1995 ; smith et al ..
Please generate the next two sentences of the article | 2003a ; stahl et al .
2005 ) . while spectacular in appearance |
7,970 | Suppose that you have an abstract for a scientific paper: we discuss functional clustering procedures for nested designs , where multiple curves are collected for each subject in the study .
we start by considering the application of standard functional clustering tools to this problem , which leads to groupings based on the average profile for each subject . after discussing some of the shortcomings of this approach
, we present a mixture model based on a generalization of the nested dirichlet process that clusters subjects based on the distribution of their curves . by using mixtures of generalized dirichlet processes ,
the model induces a much more flexible prior on the partition structure than other popular model - based clustering methods , allowing for different rates of introduction of new clusters as the number of observations increases .
the methods are illustrated using hormone profiles from multiple menstrual cycles collected for women in the early pregnancy study . .
And you have already written the first three sentences of the full article: [ sec1 ] the literature on functional data analysis has seen a spectacular growth in the last twenty years , showing promise in applications ranging from genetics [ @xcite ] to proteomics [ @xcite ] , epidemiology [ @xcite ] and oceanography [ @xcite ] . because functional data are inherently complex ,
functional clustering is useful as an exploratory tool in characterizing variability among subjects ; the resulting clusters can be used as a predictive tool or simply as a hypothesis - generating mechanism that can help guide further research .
some examples of functional clustering methods include @xcite , who use b - spline fitting coupled with @xmath0-means clustering ; @xcite , who apply @xmath0-means clustering via the principal points of random functions ; @xcite , who develop methods for sparsely sampled functional data that employ spline representations ; @xcite , where the robust @xmath0-means method for functional clustering is developed ; @xcite , who use a fourier representation for the functions along with @xmath0-means clustering ; @xcite , where a bayesian hierarchical clustering approach that relies on spline representations is proposed ; @xcite , who build a hierarchical bayesian model that employs a bayesian nonparametric mixture model on the coefficients of the wavelet representations ; and @xcite , where a @xmath0-centers functional clustering approach is developed that relies on the karhunen .
Please generate the next two sentences of the article | love representation of the underlying stochastic process generating the curves and accounts for both the means and the modes of variation differentials between clusters .
all of the functional clustering methods described above have been designed for situations where a single curve is observed for each subject or experimental condition . |
7,971 | Suppose that you have an abstract for a scientific paper: let @xmath0 be a transcendental entire map that is _ subhyperbolic _ , i.e. , the intersection of the fatou set @xmath1 and the postsingular set @xmath2 is compact and the intersection of the julia set @xmath3 and @xmath2 is finite .
assume that no asymptotic value of @xmath4 belongs to @xmath3 and that the local degree of @xmath4 at all points in @xmath3 is bounded by some finite constant .
we prove that there is a hyperbolic map @xmath5 with connected fatou set such that @xmath4 and @xmath6 are semiconjugate on their julia sets .
furthermore , we show that this semiconjugacy is a conjugacy when restricted to the escaping set @xmath7 of @xmath6 . in the case
where @xmath4 can be written as a finite composition of maps of finite order , our theorem , together with recent results on julia sets of hyperbolic maps , implies that @xmath3 is a _ pinched cantor bouquet _ , consisting of dynamic rays and their endpoints .
our result also seems to give the first complete description of topological dynamics of an entire transcendental map whose julia set is the whole complex plane . .
And you have already written the first three sentences of the full article: it is well - known that the julia set @xmath3 of a transcendental entire function @xmath4 can be the whole complex plane .
( basic definitions and notations are reviewed in section [ sec_prel ] . ) as far as we know , there is no function with this property for which the topological dynamics has been completely understood .
the results in this paper provide such a description for a wide class of examples , including maps such as @xmath8 ..
Please generate the next two sentences of the article | ( a description of the _ combinatorial _ dynamics of the latter map was previously given by schleicher in @xcite . ) in particular , we give an answer to the question of bergweiler ( personal communication ) whether the escaping set @xmath9 of a cosine map @xmath10 with strictly preperiodic critical values is connected : this is not the case ; see corollary [ cor_bergweiler ] below .
( on the other hand , there are entire maps whose julia set equals @xmath11 but for which the escaping set is connected ; see @xcite . ) in fact , our results are considerably more general . a transcendental entire map @xmath4 is called _ subhyperbolic _ if the intersection of the fatou set @xmath1 and the postsingular set @xmath2 is compact and the intersection of the julia set @xmath3 and @xmath2 is finite . |
7,972 | Suppose that you have an abstract for a scientific paper: in this paper we analyze a generic dynamical system with @xmath0 constructed via a cayley graph .
we study the hopf bifurcation and find conditions for obtaining a unique branch of periodic solutions .
our main result comes from analyzing the system under weak coupling , where we identify the conditions for heteroclinic cycle between four equilibria in the two - dimensional fixed point subspace of some of the isotropy subgroups of @xmath1 we also analyze the stability of the heteroclinic cycle .
equivariant dynamical system , cayley graph , hopf bifurcation , heteroclinic cycle . 37c80 , 37g40 , 34c15 , 34d06 , 34c15 .
And you have already written the first three sentences of the full article: the global dynamics of networks of @xmath2 coupled oscillators with different types of coupling has been studied in @xcite . in their formalism
it is shown that the symmetry group of the network can be considered a subgroup of @xmath3 , as long as the oscillators taken individually have no internal symmetries .
these ideas have been investigated in the above cited paper , for general @xmath4 and @xmath5 cases ..
Please generate the next two sentences of the article | however , it is a routine considering @xmath6 so the case @xmath0 is sometimes not explicitly taken into account .
another reason for carrying out our study is the fact that among the dihedral groups , @xmath0 is the only abelian group , which makes its action and therefore its analysis slightly different . in this paper |
7,973 | Suppose that you have an abstract for a scientific paper: i give a brief overview of the model - independent analysis of unstable baryon resonances in the @xmath0 qcd expansion .
this approach produces numerous surprising semi - quantitative phenomenological predictions that are supported by available observations . .
And you have already written the first three sentences of the full article: this talk briefly summarizes a growing body of work@xcite done with tom cohen on unstable baryon resonances in the @xmath0 qcd expansion .
more in - depth synopses appear in ref . .
the @xmath0 expansion about the large @xmath1 qcd limit has been extensively used to study baryons treated as stable states . at @xmath2.
Please generate the next two sentences of the article | the lowest - lying baryons fill a completely symmetric spin - flavor su(6 ) representation , the * 56*. although the lightest @xmath3 baryons have @xmath1 valence quarks , the su(6 ) representation remains symmetric , as one shows@xcite by imposing order - by - order ( in @xmath0 ) unitarity in @xmath4 scattering ( _ consistency conditions _ ) .
low - spin baryons in this multiplet ( analogues to @xmath5 , @xmath6 ) are split in mass at @xmath7,@xcite meaning that such states are stable for large @xmath1 . |
7,974 | Suppose that you have an abstract for a scientific paper: we calculate the spectrum of quasiparticle excitations in the core of isolated pancake vortices in clean layered superconductors .
we show that both the circular current around the vortex center as well as any transport current through the vortex core is carried by localized states bound to the core by andreev scattering .
hence the physical properties of the core are governed in clean high-@xmath0 superconductors ( e.g. the cuprate superconductors ) by the andreev bound states , and not by normal electrons as it is the case for traditional ( dirty ) high-@xmath0 superconductors . .
And you have already written the first three sentences of the full article: we discuss specific aspects of the core of a vortex line in layered high t@xmath1 superconductors .
the physics of these vortices is governed by two distinct length scales , the london penetration depth in the planes , @xmath2 , and the coherence length in the planes , @xmath3 .
the penetration depth is the electromagnetic length scale of a vortex ..
Please generate the next two sentences of the article | the physics on this length scale is well described by a combination of macroscopic electromagnetism , london s theory for supercurrents along the layers , and interlayer josephson coupling .
this description breaks down in the core of the vortex , _ |
7,975 | Suppose that you have an abstract for a scientific paper: as part of the advanced camera for survey ( acs ) virgo cluster survey , we have measured surface brightness fluctuations ( sbf ) in a sample of 100 early - type virgo galaxies .
distances derived from these measurements are needed to explore the three - dimensional structure of the virgo cluster , study the intrinsic parameters of globular clusters associated with the program galaxies , and compare with the galaxy distances derived from globular cluster luminosity functions .
our sbf measurements have been performed in the f850lp bandpass of the wide field channel of the acs on the hubble space telescope .
these are the first measurements of this kind , and we present the first sbf calibration for this bandpass .
the measured fluctuations depend on galaxy stellar population variations , which we quantify by galaxy color @xmath0 , where @xmath1 and @xmath2 are the galaxy magnitudes , respectively , in the f475w and f850lp acs filters .
we derive the following calibration for the absolute sbf magnitude @xmath3 : @xmath4 \nonumber\ ] ] in the range @xmath5 , and @xmath6 \nonumber\ ] ] in the range @xmath7 .
the quoted zero - point uncertainty here includes all sources of internal error ; there is an additional systematic uncertainty of @xmath80.15 mag , due to the uncertainty in the distance scale calibration .
physically , the two different color regimes correspond to different galaxy types : giant ellipticals and s0s at the red end , and early - type dwarfs at the blue end . for the first time in sbf studies , we are able to provide a firm empirical calibration of sbf in early type dwarf galaxies .
our results agree with stellar population model predictions from bruzual & charlot ( 2003 ) in the range @xmath9 , while our empirical slope is somewhat steeper than the theoretical prediction in the range @xmath10 . .
And you have already written the first three sentences of the full article: the advanced camera for surveys ( acs ; ford et al . 1998 ) virgo cluster survey is a project based on observations with the acs on the _ hubble space telescope _ ( ) , aimed at the exploration of the properties of 100 early type galaxies in the virgo cluster , the study of their globular cluster systems , and the reconstruction of virgo s three dimensional structure . to measure the galaxy distances needed to realize these goals , we have used measurements of surface brightness fluctuations ( sbf ) .
the sbf method was first proposed by tonry & schneider ( 1988 ) and it is based on the fact that the variance of normalized poissonian fluctuations of the galaxy stellar population depends on galaxy distance ( for reviews see jacoby et al .
1992 and blakeslee et al . 1999 ) . at present.
Please generate the next two sentences of the article | , sbf measurements have been used to determine galaxy distances out to @xmath11 7000 km s@xmath12 , using data from ground based telescopes and ( ajhar 1997 , 2001 ; tonry 1997 , 2001 ; jensen 1999 , 2003 ; blakeslee 2001 , 2002 ; mei 2001 , 2003 ; liu 2001 , 2002 ; mieske et al .
2003 ; and references in mei et al . |
7,976 | Suppose that you have an abstract for a scientific paper: in the paper we treat gale diagrams in a combinatorial way .
the interpretation allows to describe simplicial complexes which are alexander dual to boundaries of simplicial polytopes and , more generally , to nerve - complexes of general polytopes .
this technique and recent results of n.yu.erokhovets are combined to prove the following : buchstaber invariant @xmath0 of a convex polytope equals 1 if and only if @xmath1 is a pyramid . in general , we describe a procedure to construct polytopes with @xmath2 .
the construction has purely combinatorial consequences .
we also apply gale duality to the study of bigraded betti numbers and @xmath3-vectors of polytopes . .
And you have already written the first three sentences of the full article: gale duality is a classical notion in convex geometry . since its appearance in @xcite it allowed to prove many strong and nontrivial results for convex polytopes and configurations of points on a sphere (
the survey of this field can be found in @xcite ) . in this paper
we describe a surprisingly simple connection between gale diagrams and combinatorial alexander duality . for any set of points on a sphere @xmath4.
Please generate the next two sentences of the article | we associate a covering of @xmath4 by hemispheres . from the theory of gale duality
follows that the nerves of such coverings are exactly those complexes , which are alexander dual to boundaries of simplicial polytopes , or , more generally , to nerve - complexes of polytopes ( see claim [ claimgalealex ] for the precise statement ) . on one hand , this gives a combinatorial characterization of complexes dual to boundaries of simplicial polytopes . on the other hand , geometrical considerations , involving coverings by hemispheres allowed to prove particular statements about convex polytopes . |
7,977 | Suppose that you have an abstract for a scientific paper: fluid dynamics ; heat conductivity we discuss heat conductivity from the point of view of a variational multi - fluid model , treating entropy as a dynamical entity .
we demonstrate that a two - fluid model with a massive fluid component and a massless entropy can reproduce a number of key results from extended irreversible thermodynamics .
in particular , we show that the entropy entrainment is intimately linked to the thermal relaxation time that is required to make heat propagation in solids causal .
we also discuss non - local terms that arise naturally in a dissipative multi - fluid model , and relate these terms to those of phonon hydrodynamics .
finally , we formulate a complete heat conducting two - component model and discuss briefly the new dissipative terms that arise . .
And you have already written the first three sentences of the full article: heat conductivity is a central problem in thermodynamics .
it is well known that the classical description in irreversible thermodynamics , essentially fourier s law , has unattractive features . in particular
, it predicts an instantaneous propagation of thermal signals ..
Please generate the next two sentences of the article | this is in contradiction to the expected hyperbolic nature of physical laws .
in fact , the associated non - causality would be completely unacceptable within a relativistic theory . resolving this issue |
7,978 | Suppose that you have an abstract for a scientific paper: discovery of supersymmetric ( susy ) particles at the large hadron collider ( lhc ) has been studied for the models where squarks and gluino are much heavier than the lightest supersymetric particle ( lsp ) . in this paper
, we investigate the susy discovery in the models with degenerated mass spectrum up to @xmath0 .
such mass spectrum is predicted in certain parameter region of the mixed modulas anomaly mediation ( mmam ) model .
we find that the effective transverse mass of the signal for the degenerated parameters shows the distribution similar to that of the background . experimental sensitivity of the susy particles at the lhc therefore depends on the uncertainty of the background in this class of model .
we also find that susy signal shows an interesting correlation between @xmath1 and @xmath2 which may be used to determine the signal region properly to enhance the s / n ratio even if the sparticle masses are rather degenerated .
the structure is universal for the models with new heavy colored particles decaying into visible particles and a stable neutral particle , dark matter . .
And you have already written the first three sentences of the full article: minimal supersymmetric standard model ( mssm ) is one of the most promising candidates of the physics beyond the standard model ( sm ) that may solve the hierarchy problem in the higgs sector @xcite .
the model predicts a set of superpartners ( sparticles ) whose charges are exactly the same to that of the sm partners but the spins are different by one half .
these sparticles will be directly searched at the large hadron collider ( lhc ) at cern , which is a @xmath3 collider with 14 tev center of mass energy ..
Please generate the next two sentences of the article | the lhc is scheduled to start in 2007 .
one of the interesting features of the mssm model is the conserved r parity , and all sparticles are assigned to have odd r parity . |
7,979 | Suppose that you have an abstract for a scientific paper: we present stellar structure and atmosphere models of metal - free stars and examine them from a cosmological point of view .
metal - free stars exhibit high effective temperatures and small sizes relative to metal - enriched stars of equal mass .
these unique physical characteristics enhance the ionizing photon production by metal - free stars , particularly in the ( @xmath0 ryd ) continuum .
the star formation rate of metal - free stars necessary to reionize the hydrogen in the universe by @xmath1 is consistent with the inferred star formation rate at that epoch .
however , the hard stellar spectra are inconsistent with the observations of opacity in the igm at @xmath2 , indicating that the period of metal - free star formation ended before that epoch .
we examine the effects of these stars on the ionization balance of the igm , the radiative feedback of the first luminous objects , and the extragalactic radiation field .
we comment on the prospects for detecting metal - free stellar populations with the @xmath3 and @xmath4 recombination lines of . .
And you have already written the first three sentences of the full article: we know from observational constraints that the hydrogen in the intergalactic medium ( igm ) was reionized by redshift @xmath5 ( schneider , schmidt , & gunn 1991 ) and that the was reionized at @xmath2 ( reimers et al .
1997 ) . however , the exact nature of the ionizing sources is still uncertain .
the observed drop in the space density of bright quasars at @xmath6 ( pei 1995 ) suggests that early stellar populations played a role in the reionization of hydrogen , but it is not known whether hot stars produced photons at rates sufficient to ionize the universe before this epoch ..
Please generate the next two sentences of the article | our understanding of reionization is closely connected to our knowledge of the extragalactic radiation field .
models of reionization assume an extragalactic spectrum composed of the distinct intrinsic spectra of active galactic nuclei ( agn ) and star - forming galaxies . |
7,980 | Suppose that you have an abstract for a scientific paper: this paper presents equational - based logics for proving first order properties of programming languages involving effects .
we propose two dual inference system patterns that can be instanciated with monads or comonads in order to be used for proving properties of different effects .
the first pattern provides inference rules which can be interpreted in the kleisli category of a monad and the cokleisli category of the associated comonad . in a dual way
, the second pattern provides inference rules which can be interpreted in the cokleisli category of a comonad and the kleisli category of the associated monad .
the logics combine a 3-tier effect system for terms consisting of pure terms and two other kinds of effects called constructors / observers and modifiers , and a 2-tier system for up - to - effects and strong equations .
each pattern provides generic rules for dealing with any monad ( respectively comonad ) , and it can be extended with specific rules for each effect .
the paper presents two use cases : a language with exceptions ( using the standard monadic semantics ) , and a language with state ( using the less standard comonadic semantics ) .
finally , we prove that the obtained inference system for states is hilbert - post complete . .
And you have already written the first three sentences of the full article: a _ software design pattern _ is not a finished design , it is a description or template that can be instanciated in order to be used in many different situations . in this paper , we propose _ inference system patterns _ that can be instanciated with monads or comonads in order to be used for proving properties of different effects . in order to formalize computational effects one can choose between types and effects systems @xcite , monads @xcite and their associated lawvere theories @xcite , comonads @xcite , or decorated logics @xcite . starting with moggi s seminal paper @xcite and its application to haskell @xcite
, various papers deal with the effects arising from a monad , for instance @xcite .
each of these approaches rely on some classification of the syntactic expressions according to their interaction with effects . in this paper.
Please generate the next two sentences of the article | we use decorated logics which , by extending this classification to equations , provide a proof system adapted to each effect .
this paper presents equational - based logics for proving first order properties of programming languages involving effects . |
7,981 | Suppose that you have an abstract for a scientific paper: resonant transport in a hybrid semiconductor - superconductor microstructure grown by mbe on gaas is presented .
this structure experimentally realizes the prototype system originally proposed by de gennes and saint - james in 1963 in _ all_-metal structures .
a low temperature single peak superimposed to the characteristic andreev - dominated subgap conductance represents the mark of such resonant behavior .
random matrix theory of quantum transport was employed in order to analyze the observed magnetotransport properties and ballistic effects were included by directly solving the bogoliubov - de gennes equations . in this contribution
we report the experimental observation of de gennes - saint - james ( dgsj)-type resonances @xcite in a microstructure consisting of a nb / gaas / algaas / gaas hybrid microjunction .
this microstructure realizes the model system introduced by de gennes and saint - james in 1963 , consisting of a superconductor - normal metal - insulator - normal metal - type ( snin ) layer sequence .
multiple reflections off the superconductive gap ( i.e. , andreev reflections @xcite ) and off the insulating barrier ( i.e. , normal reflections ) can give rise to quasi - bound states @xcite that manifest themselves as conductance resonances .
this result was made possible by the exploitation of semiconductor epitaxial growth to tailor electronic states according to the original dgsj model system .
we analyzed the data within the random matrix theory of quantum transport and included ballistic effects by directly solving the bogoliubov - de gennes equations in a model potential profile @xcite .
our description of the system is confirmed by the observed temperature and magnetic - field dependence . .
And you have already written the first three sentences of the full article: a sketch of the nb / gaas / algaas structure is shown in fig .
the semiconductor portion consists of a 1 @xmath0 m thick @xmath1-gaas(001 ) buffer layer si - doped nominally at @xmath2 @xmath3 grown by molecular beam epitaxy ( mbe ) on a @xmath1-gaas(001 ) substrate , followed by a 4 nm thick al@xmath4ga@xmath5as barrier .
this was followed by the growth of a 12 nm thick gaas(001 ) epilayer si - doped at @xmath2 @xmath3 and by 14 nm of gaas doped by a sequence of six si @xmath6-doped layers spaced by 2 nm . a 1-@xmath0m - thick amorphous as cap layer.
Please generate the next two sentences of the article | was deposited in the mbe growth chamber to protect the surface during transfer in air to an uhv sputter - deposition / surface analysis system .
after thermal desorption of the as protective cap layer , a 100-nm - thick nb film was then deposited _ in situ _ by dc - magnetron sputtering . |
7,982 | Suppose that you have an abstract for a scientific paper: we use a numerical simulation of a loose group containing a milky way halo to probe that in the hierarchical universe the magellanic clouds and some dsphs have been accreted into the milky way halo from a late infalling group of dwarfs .
our simulations show that the tidal breakup of the magellanic group occurs before it enters the milky way halo .
only half of the satellites contributed from the group are predicted to be inside the milky way virial radius .
half of its subhalos survive outside the current virial radius in the form of satellites , whereas the remaining material contributes to the diffuse milky way halo . at @xmath0
the disrupted group contributes less than 10% to the milky way halo mass but 20% of the brightest dwarf galaxies of the milky way have been part of this group .
this scenario points out that some dsphs might have been formed away from giant spirals and been accreted already as spheroids , by a late infall group in contrast with the classical picture of tidal stripping of dsph formation models .
this would naturally explain several peculiarities of the local dsph : why draco and the other luminous dsphs exist compared to other ultra - faint satellite galaxies , the location of tucana and cetus in the outskirts of the local group and the mismatch in metallicity between the stellar halo of the milky way and the dwarf galaxies that many have suspected dissolved to build it . .
And you have already written the first three sentences of the full article: an unequivocal prediction of cold dark matter models ( cdm ) is that the mass of the milky way , in the form of its dark matter halo , builds up hierarchically , by accretion of lower - mass halos .
when these sub - systems ( often refereed to as subhalos ) escape the tidal disruption in the milky way halo they survive in the form of satellite galaxies until today .
numerical simulations confirmed the theory predicting 500 satellites within 500 kpc from the milky way center ( kauffman et al ..
Please generate the next two sentences of the article | 1993 ; klypin et al . 1999 ; moore et al .
the modest populations of observed dwarf galaxies orbiting the milky way and andromeda , however , seems to conflict with this prediction . |
7,983 | Suppose that you have an abstract for a scientific paper: the following result has been shown recently in the form of a dichotomy : for every total clone @xmath0 on @xmath1 , the set @xmath2 of all partial clones on @xmath3 whose total component is @xmath0 , is either finite or of continuum cardinality . in this paper
we show that the dichotomy holds , even if only strong partial clones are considered , i.e. , partial clones which are closed under taking subfunctions : for every total clone @xmath0 on @xmath3 , the set @xmath4 of all strong partial clones on @xmath3 whose total component is @xmath0 , is either finite or of continuum cardinality . .
And you have already written the first three sentences of the full article: let @xmath5 be an arbitrary finite set .
in the case we deal with boolean clones we have @xmath6 .
a function @xmath7 is called a total function on @xmath5 . a function @xmath8 with @xmath9.
Please generate the next two sentences of the article | is called partial function on @xmath5 and we denote the domain by @xmath10 .
the set @xmath11 is the set of all total functions on @xmath5 , and @xmath12 is the set of all partial functions on @xmath5 . |
7,984 | Suppose that you have an abstract for a scientific paper: the classical approximation may be applied to a number of problems in non - equilibrium field theory . the principles and limits of classical real - time lattice simulations
are presented , with particular emphasis on the definition of particle numbers and energies and on applications to the earliest stages of heavy - ion collisions .
mathmargin = 0pt .
And you have already written the first three sentences of the full article: one of the most important predictions of lattice qcd is the existence of a transition from ordinary hadronic matter , where quarks and gluons are confined , to a quark gluon plasma at high temperatures .
current estimates are that this transition takes place at @xmath0 mev , and is most likely a crossover at zero chemical potential . at higher chemical potential a first - order phase transition is predicted , ending in a tricritical point at @xmath1 mev .
these predictions are currently being put to the test at rhic and other heavy - ion colliders . however , interpreting the results of these experiments and comparing them to lattice qcd predictions is far from straightforward ..
Please generate the next two sentences of the article | one important reason for this is that the process to a large extent takes place out of thermal equilibrium , and equilibrium field theory methods such as lattice monte carlo are therefore not sufficient . one major , still unsolved puzzle of heavy - ion physics is whether the system ever actually reaches thermal equilibrium , and if so , what the equilibration time is .
many aspects of the collision can be successfully described ( eg , using hydrodynamics @xcite ) by assuming a very short equilibration time of 1 @xmath2 , but it is far from understood how this would come about . |
7,985 | Suppose that you have an abstract for a scientific paper: it is believed that almost any pair of people in the world can be connected to one another by a short chain of intermediate acquaintances , of typical length about six .
this phenomenon , colloquially referred to as the `` six degrees of separation , '' has been the subject of considerable recent interest within the physics community .
this paper provides a short review of the topic .
# 1([#1 ] ) # 1[#1 ] # 1[#1 ] # 1[#1 ] # 1#1 o # 1 # 1 # 1 .
And you have already written the first three sentences of the full article: the united nations department of economic and social affairs estimates that the population of the world exceeded six billion people for the first time on october 12 , 1999 .
there is no doubt that the world of human society has become quite large in recent times .
nonetheless , people routinely claim that , global statistics notwithstanding , it s still a small world . and in a certain sense they are right . despite the enormous number of people on the planet , the structure of social networks .
Please generate the next two sentences of the article | the map of who knows whom is such that we are all very closely connected to one another ( kochen 1989 , watts 1999 ) .
one of the first quantitative studies of the structure of social networks was performed in the late 1960s by stanley milgram , then at harvard university ( milgram 1967 ) . |
7,986 | Suppose that you have an abstract for a scientific paper: in this paper , the problem of distributed power allocation is considered for the downlink of a cloud radio access network ( cran ) that is coexisting with a heterogeneous network . in this multi - tier system ,
the heterogeneous network base stations ( bss ) as well as the cran remote radio heads seek to choose their optimal power to maximize their users rates .
the problem is formulated as a noncooperative game in which the players are the cran s cloud and the bss .
given the difference of capabilities between the cran and the various bss , the game is cast within the framework of cognitive hierarchy theory . in this framework , players are organized in a hierarchy in such a way that a player can choose its strategy while considering players of only similar or lower hierarchies .
using such a hierarchical design , one can reduce the interference caused by the cran and high - powered base stations on low - powered bss . for this game ,
the properties of the nash equilibrium and the cognitive hierarchy equilibrium are analyzed .
simulation results show that the proposed cognitive hierarchy model yields significant performance gains , in terms of the total rate , reaching up to twice the rate achieved by a classical noncooperative game s nash equilibrium . .
And you have already written the first three sentences of the full article: the deployment of a cloud - based radio access network ( cran ) is expected to be an integral part of 5 g networks @xcite . in cran ,
remote radio heads ( rrhs ) , which are small radio antennas responsible for transmission , cooperate to serve their wireless users . to achieve such coordination ,
the rrhs are connected through a fronthaul link to a control unit ( cu ) that performs efficient signal processing ..
Please generate the next two sentences of the article | however , in cran , the fronthaul links are often of finite capacity @xcite , and thus , the number of rrhs connected to the cu will be limited .
thus , the cran will need to co - exist with the small cell base stations ( bss ) of an existing heterogeneous cellular network ( hetnet ) . |
7,987 | Suppose that you have an abstract for a scientific paper: tensor network algorithms provide a suitable route for tackling real - time dependent problems in lattice gauge theories , enabling the investigation of out - of - equilibrium dynamics .
we analyze a u(1 ) lattice gauge theory in ( 1 + 1 ) dimensions in the presence of dynamical matter for different mass and electric field couplings , a theory akin to quantum - electrodynamics in one - dimension , which displays string - breaking : the confining string between charges can spontaneously break during quench experiments , giving rise to charge - anticharge pairs according to the schwinger mechanism .
we study the real - time spreading of excitations in the system by means of electric field and particle fluctuations : we determine a dynamical state diagram for string breaking and quantitatively evaluate the time - scales for mass production .
we also show that the time evolution of the quantum correlations can be detected via bipartite von neumann entropies , thus demonstrating that the schwinger mechanism is tightly linked to entanglement spreading .
to present the variety of possible applications of this simulation platform , we show how one could follow the real - time scattering processes between mesons and the creation of entanglement during scattering processes . finally , we test the quality of quantum simulations of these dynamics , quantifying the role of possible imperfections in cold atoms , trapped ions , and superconducting circuit systems .
our results demonstrate how entanglement properties can be used to deepen our understanding of basic phenomena in the real - time dynamics of gauge theories such as string breaking and collisions . .
And you have already written the first three sentences of the full article: the mechanism of quark confinement stands as a key concept in our understanding of the fundamental interactions in high energy physics @xcite . as a quark and an anti - quark
are pulled apart , the energy stored in the gluon string connecting them grows linearly with distance , due to the confining nature of strong nuclear forces described by quantum - chromodynamics ( qcd ) . in gauge theories hosting dynamical charges , there exists a critical length scale at which the confining string breaks , creating particle - antiparticle pairs which reduce the energy density in the string and give rise to the hadrons at the string edges @xcite .
the _ static properties _ of string breaking have been widely explored using a variety of lattice methods , wherein the effective string potential separating static charges can be extracted by the polyakov or wilson loops @xcite ..
Please generate the next two sentences of the article | however , the _ real - time dynamics _ of gauge theories are usually biased by a severe sign problem , and as such can not be accessed using lattice montecarlo simulations @xcite . in this paper , we apply tensor network ( tn ) methods in order to study the real - time dynamics of a lattice gauge theory ( lgt ) with dynamical charges and quantum gauge degrees of freedom in one dimensional systems . in particular , we investigate the real - time string - breaking dynamics in abelian u(1 ) lgts in ( 1 + 1)d , which share with qcd the basic feature of confinement . in recent years
, efficient numerical methods based on tns have found widespread application to the real - time dynamics of strongly correlated low - dimensional systems @xcite . |
7,988 | Suppose that you have an abstract for a scientific paper: we consider the cosmology of the ricci - tensor - squared gravity in the palatini variational approach .
the gravitational action of standard general relativity is modified by adding a function @xmath0 to the einstein - hilbert action , and the palatini variation is used to derive the field equations
. a general method of obtaining the background and first - order covariant and gauge - invariant perturbation equations is outlined . as an example , we consider the cosmological constraints on such theories arising from the supernova type ia and cosmic microwave background observations .
we find that the best fit to the data is a non - null leading - order correction to einstein gravity , but the current data exhibit no significant preference over the concordance model .
the growth of non - relativistic matter density perturbations at late times is also analyzed , and we find that a scale - dependent ( positive or negative ) sound - speed - squared term generally appears in the growth equation for small - scale density perturbations .
we also estimate the observational bound imposed by the matter power spectrum for the model with @xmath1 to be roughly @xmath2 so long as the dark matter does not possess compensating anisotropic stresses . .
And you have already written the first three sentences of the full article: the accumulating astronomical evidence for an accelerating cosmic expansion has stimulated many investigations into the nature of the dark energy , or other possible deviant gravitational effects , which might be responsible for this unexpected dynamics ( for a review see , _
e.g. _ , @xcite ) . besides proposing to add some new ( and purely theoretical ) matter species into the energy budget of the universe ,
many investigators have also focused their attentions on modifying general relativity ( gr ) on the largest scales , so as to introduce significant modifications in the behaviour of gravity at late times when it is comparatively weak ..
Please generate the next two sentences of the article | one example of the latter sort is provided by the family of @xmath3 gravity models , which had also been considered before the discovery of cosmic acceleration ( see for example refs .
@xcite ) with reference to alternative forms of inflation and the existence of singularities . in refs . |
7,989 | Suppose that you have an abstract for a scientific paper: in this work , we predict two charged charmonium - like enhancement structures close to the @xmath0 and @xmath1 thresholds , where the initial single pion emission mechanism is introduced in the hidden - charm dipion decays of higher charmonia @xmath2 , @xmath3 , @xmath4 and charmonium - like state @xmath5 .
we suggest besiii to search for these structures in the @xmath6 , @xmath7 and @xmath8 invariant mass spectra of the @xmath2 decays into @xmath9 , @xmath10 and @xmath11 .
in addition , the experimental search for these enhancement structures in the @xmath6 , @xmath7 and @xmath12 invariant mass spectra of the @xmath13 hidden - charm dipion decays will be accessible at belle and babar . .
And you have already written the first three sentences of the full article: in the past years , experimentalist has made big progress on the search for the charmonium - like states , the so - called xyz states , in the @xmath14 meson decay , the @xmath15 collision , the @xmath16 fusion process , which have aroused extensive interest in revealing the underlying properties of the observed charmonium - like states ( see refs .
@xcite for a review ) .
the study of charmonium - like states is a research field full of challenges and opportunities in hadron physics ..
Please generate the next two sentences of the article | very recently the belle collaboration @xcite reported two charged @xmath17 structures around 10610 mev and 10650 mev by studying the @xmath18 ( @xmath19 ) and @xmath20 ( @xmath21 ) invariant mass spectra of @xmath22 hidden - bottom decay channels ( see refs .
@xcite for theoretical progress ) . in ref . |
7,990 | Suppose that you have an abstract for a scientific paper: the detection of transiting extrasolar planets requires high - photometric quality and long - duration photometric stellar time - series . in this paper
, we investigate the advantages provided by the antarctic observing platform for planet transit detections during its long winter period , which allows for relatively long , uninterrupted time - series .
our calculations include limiting effects due to the sun and moon , cloud coverage and the effect of reduced photometric quality for high extinction of target fields .
we compare the potential for long time - series from with a single site in chile , a three - site low - latitude network as well as combinations of with chile and the network , respectively .
is one of the prime astronomical sites on earth for obtaining uninterrupted long - duration observations in terms of prospects for a high observational duty cycle .
the duty cycle of a project can , however , be significantly improved by integrating into a network of sites . .
And you have already written the first three sentences of the full article: extrasolar planets are currently detected via indirect methods .
the radial velocity technique has proved most successful in recent years .
however , photometric measurements of planets transiting in front of their central star through the line - of - sight to earth have already provided more than 30 planet detections in the past years ..
Please generate the next two sentences of the article | many more transiting planet detections are expected in the very near future by the space missions corot @xcite and kepler @xcite . combining both methods allows the derivation of planetary radii , true masses and thus , the mean density of extrasolar planets .
transiting planets are therefore of particular importance to investigate basic planetary parameters . |
7,991 | Suppose that you have an abstract for a scientific paper: the phenomenon of radicalization is investigated within a mixed population composed of core and sensitive subpopulations .
the latest includes first to third generation immigrants .
respective ways of life may be partially incompatible . in case of a conflict
core agents behave as inflexible about the issue . in contrast
, sensitive agents can decide either to live peacefully adjusting their way of life to the core one , or to oppose it with eventually joining violent activities .
the interplay dynamics between peaceful and opponent sensitive agents is driven by pairwise interactions .
these interactions occur both within the sensitive population and by mixing with core agents .
the update process is monitored using a lotka - volterra - like ordinary differential equation . given an initial tiny minority of opponents that coexist with both inflexible and peaceful agents , we investigate implications on the emergence of radicalization .
opponents try to turn peaceful agents to opponents driving radicalization . however , inflexible core agents may step in to bring back opponents to a peaceful choice thus weakening the phenomenon . the required minimum individual core involvement to actually curb radicalization
is calculated.it is found to be a function of both the majority or minority status of the sensitive subpopulation with respect to the core subpopulation and the degree of activeness of opponents .
the results highlight the instrumental role core agents can have to hinder radicalization within the sensitive subpopulation .
some hints are outlined to favor novel public policies towards social integration . .
And you have already written the first three sentences of the full article: the phenomenon of radicalization @xcite is of central interest in the context of criminality and terrorism .
it is currently spreading all over the world including european countries .
the recent unprecedented terrorists attacks in paris ( november 13 , 2015 ) and brussels ( march 22 , 2016 ) took life of respectively 130 and 32 persons with over 300 wounded in each case @xcite ..
Please generate the next two sentences of the article | it puts at a very high level the burden on making substantial progress in the mastering of the issue . over the years
sociologists and social - psychologists have contributed a good deal of work to the phenomenon @xcite . |
7,992 | Suppose that you have an abstract for a scientific paper: miniboone began running in antineutrino mode on 19 january , 2006 .
we describe the sensitivity of miniboone to lsnd - like @xmath0 oscillations and outline a program of antineutrino cross - section measurements necessary for the next generation of neutrino oscillation experiments .
we describe three independent methods of constraining wrong - sign ( neutrino ) backgrounds in an antineutrino beam , and their application to the miniboone antineutrino analyses . .
And you have already written the first three sentences of the full article: miniboone @xcite is a neutrino oscillation experiment at fermilab , designed to confirm or rule out the hypothesis that the lsnd @xmath0 excess @xcite is due to @xmath1 oscillations .
a general description of the experiment can be found elsewhere @xcite .
heretofore , miniboone has been taking data in neutrino mode , searching for @xmath2 oscillations ..
Please generate the next two sentences of the article | however , in some scenarios involving cp and cpt violation , oscillations may occur only in antineutrinos .
thus , searching for oscillations in antineutrinos is a crucial test @xcite . |
7,993 | Suppose that you have an abstract for a scientific paper: we study the stability under the perturbation and the related anti - evaporation of the nariai space - time in bigravity .
if we impose specific condition for the solutions and parameters , we obtain asymptotically de sitter space - time , and show the existence of the nariai space - time as a background solution . considering the perturbation around the nariai space - time up to first order
, we investigate the behavior of black hole horizon .
we show that the anti - evaporation does not occur on the classical level in the bigravity . .
And you have already written the first three sentences of the full article: one can find that there exist many reasons and motivations to consider alternative theories of gravity to the general relativity .
some theories are motivated by the modifications in infrared regime and they mainly aim to resolve a question about the dark energy .
for instance , @xmath0 gravity @xcite can explain the accelerating expansion of current universe without the cosmological constant and avoid the hierarchy problem ..
Please generate the next two sentences of the article | others are motivated by the modifications in ultraviolet regime and they are often associated with the effects of quantum gravity @xcite .
higher - curvature theories typified by curvature - squared and the gauss - bonnet terms are induced from quantum corrections . naturally , challenges to the theory beyond general relativity themselves are important because there is no fundamental reason to choose the einstein - hilbert action or einstein s equation over many kind of alternatives . |
7,994 | Suppose that you have an abstract for a scientific paper: the point - agape collaboration is currently searching for massive compact halo objects ( machos ) towards the andromeda galaxy ( m31 ) . the survey aims to exploit the high inclination of the m31 disk , which causes an asymmetry in the spatial distribution of m31 machos . here
, we investigate the effects of halo velocity anisotropy and flattening on the asymmetry signal using simple halo models . for a spherically symmetric and isotropic halo , we find that the underlying pixel - lensing rate in far - disk m31 machos is more than 5 times the rate of near - disk events .
we find that the asymmetry is increased further by about 30% if the machos occupy radial orbits rather than tangential orbits , but is substantially reduced if the machos lie in a flattened halo .
however , even for haloes with a minor - to - major axis ratio @xmath0 , the numbers of m31 machos in the far - side outnumber those in the near - side by a factor of @xmath12 .
there is also a distance asymmetry , in that the events on the far - side are typically further from the major axis .
we show that , if this positional information is exploited in addition to number counts , then the number of candidate events required to confirm asymmetry for a range of flattened and anisotropic halo models is achievable , even with significant contamination by variable stars and foreground microlensing events . for pixel - lensing surveys which probe a representative portion of the m31 disk ,
a sample of around 50 candidates is likely to be sufficient to detect asymmetry within spherical haloes , even if half the sample is contaminated , or to detect asymmetry in haloes as flat as @xmath0 provided less than a third of the sample comprises contaminants .
we also argue that , provided its mass - to - light ratio is less than 100 , the recently observed stellar stream around m31 is not problematic for the detection of asymmetry . .
And you have already written the first three sentences of the full article: continuing disagreement as to whether massive compact halo objects ( machos ) have been detected by microlensing experiments looking towards the magellanic clouds highlights the need for other microlensing targets ( e.g. , kerins 2001 ) . the andromeda galaxy ( m31 )
presents an opportune target in this respect .
the disk of m31 is highly inclined ( @xmath2 ) , with the consequence that lines of sight to disk stars in the north - west or near side of m31 are shorter than those to the south - east or far side . microlensing by a spheroidal dark halo will have a characteristic signature with an excess of events on the far side of the m31 disk ( crotts 1992 ; baillon et al.1993 ) ..
Please generate the next two sentences of the article | this asymmetric signal is absent for variable stars or stellar microlenses in the disk of m31 . a number of groups ( e.g. , aurire et al .
2001 ; riffeser et al . 2001 ; calchi - novati et al . 2002 ; crotts et al . |
7,995 | Suppose that you have an abstract for a scientific paper: we discuss recent results from global electroweak fits and from the tevatron and review the motivation for physics at the @xmath0 energy scale . .
And you have already written the first three sentences of the full article: we live in exciting times for particle physics .
the tevatron run ii program is producing new physics results , which will be followed by the startup of the lhc in three years .
these machines have a rich physics menu of new physics searches , precision measurements , qcd studies , @xmath1 , @xmath2 , and @xmath3 quark physics , and much more ..
Please generate the next two sentences of the article | we are in an enviable position .
we have an electroweak theory which is consistent with all data , but which predicts new physics waiting to be discovered at the tevatron and the lhc . |
7,996 | Suppose that you have an abstract for a scientific paper: we present the first detailed chemical abundance analysis of the old 8.2 gyr solar twin , hip 102152 .
we derive differential abundances of 21 elements relative to the sun with precisions as high as 0.004 dex ( @xmath01% ) , using ultra high - resolution ( r = 110,000 ) , high s / n uves spectra obtained on the 8.2-m very large telescope .
our determined metallicity of hip 102152 is [ fe / h ] = -0.013 @xmath1 0.004 .
the atmospheric parameters of the star were determined to be 54 k cooler than the sun , 0.09 dex lower in surface gravity , and a microturbulence identical to our derived solar value .
elemental abundance ratios examined vs. dust condensation temperature reveal a solar abundance pattern for this star , in contrast to most solar twins .
the abundance pattern of hip 102152 appears to be the most similar to solar of any known solar twin .
abundances of the younger , 2.9 gyr solar twin , 18 sco , were also determined from uves spectra to serve as a comparison for hip 102152 .
the solar chemical pattern of hip 102152 makes it a potential candidate to host terrestrial planets , which is reinforced by the lack of giant planets in its terrestrial planet region .
the following non - local thermodynamic equilibrium li abundances were obtained for hip 102152 , 18 sco , and the sun : log @xmath2 ( li ) = 0.48 @xmath1 0.07 , 1.62 @xmath1 0.02 , and 1.07 @xmath1 0.02 , respectively .
the li abundance of hip 102152 is the lowest reported to date for a solar twin , and allows us to consider an emerging , tightly constrained li - age trend for solar twin stars . .
And you have already written the first three sentences of the full article: when compared to most stars with similar stellar parameters , the sun displays an anomalous chemical abundance pattern . to date , high - resolution spectroscopic chemical abundance analyses offer that only @xmath315% of solar type stars have abundance patterns similar to the sun ( melndez et al . 2009 ; ramrez et al .
the disparity between the sun and other solar twins has been demonstrated in a number of studies ( e.g. , melndez et al .
2009 ; ramrez et al ..
Please generate the next two sentences of the article | 2010 , 2011 ; gonzalez et al . 2010a ; schuler et al . 2011 ) , and is possibly due to the formation of terrestrial planets .
planetesimal and terrestrial planet formation may have imprinted a signature in the solar composition by locking - up refractory elements in the surrounding disk , and leaving behind material low in refractory elements to later accrete onto the sun . in this letter , we present elemental abundance ratios as a function of condensation temperature for the @xmath38.2 gyr old solar twin hip 102152 ( hd 197027 ) . |
7,997 | Suppose that you have an abstract for a scientific paper: the bilateral filter is known to be quite effective in denoising images corrupted with small dosages of additive gaussian noise .
the denoising performance of the filter , however , is known to degrade quickly with the increase in noise level .
several adaptations of the filter have been proposed in the literature to address this shortcoming , but often at a substantial computational overhead . in this paper , we report a simple pre - processing step that can substantially improve the denoising performance of the bilateral filter , at almost no additional cost .
the modified filter is designed to be robust at large noise levels , and often tends to perform poorly below a certain noise threshold . to get the best of the original and the modified filter , we propose to combine them in a weighted fashion , where the weights are chosen to minimize ( a surrogate of ) the oracle mean - squared - error ( mse ) .
the optimally - weighted filter is thus guaranteed to perform better than either of the component filters in terms of the mse , at all noise levels .
we also provide a fast algorithm for the weighted filtering . visual and quantitative denoising results on standard test images
are reported which demonstrate that the improvement over the original filter is significant both visually and in terms of psnr .
moreover , the denoising performance of the optimally - weighted bilateral filter is competitive with the computation - intensive non - local means filter .
image denoising , bilateral filter , unbiased risk estimator , fast algorithm . .
And you have already written the first three sentences of the full article: we consider the standard problem of denoising grayscale images that are corrupted with additive white gaussian noise @xcite . in this setup
, we are given the _ corrupted _ ( or _ noisy _ ) image @xmath0 where @xmath1 is some finite rectangular domain of @xmath2 , @xmath3 is the unknown _ clean _ image , @xmath4 are independent and distributed as @xmath5 , and @xmath6 is the noise level .
the goal is find a _ denoised _.
Please generate the next two sentences of the article | estimate @xmath7 of the clean image from the corrupted samples .
the denoised image should visually resemble the clean image . |
7,998 | Suppose that you have an abstract for a scientific paper: in this paper , we investigate the development of generalized synchronization ( gs ) on typical complex networks , such as scale - free networks , small - world networks , random networks and modular networks . by adopting the auxiliary - system approach to networks ,
we show that gs can take place in oscillator networks with both heterogeneous and homogeneous degree distribution , regardless of whether the coupled chaotic oscillators are identical or nonidentical . for coupled identical oscillators on networks
, we find that there exists a general bifurcation path from initial non - synchronization to final global complete synchronization ( cs ) via gs as the coupling strength is increased . for coupled nonidentical oscillators on networks , we further reveal how network topology competes with the local dynamics to dominate the development of gs on networks .
especially , we analyze how different coupling strategies affect the development of gs on complex networks .
our findings provide a further understanding for the occurrence and development of collective behavior in complex networks . .
And you have already written the first three sentences of the full article: synchronization in coupled chaotic oscillators has been extensively studied in the past twenty years @xcite , including complete synchronization @xcite , generalized synchronization @xcite , and phase synchronization ( ps ) @xcite , etc . in cs ,
the dynamics of two coupled systems totally coincide with each other ; in gs , certain functional relation exists between the dynamics of two coupled systems which are usually nonidentical .
moreover , ps is a weaker synchronization form in which the phases of two oscillators can be locked while their amplitudes remain uncorrelated and chaotic ..
Please generate the next two sentences of the article | recently , the study of synchronization has been extended to the area of complex networks @xcite .
for example , synchronization on small - world networks @xcite , scale - free networks @xcite , modular networks @xcite , weighted networks @xcite , and gradient networks @xcite , have been investigated . |
7,999 | Suppose that you have an abstract for a scientific paper: supernova ( sn ) 2006gy is an extremely luminous type iin sn characterized by the bright peak magnitude @xmath0 @xmath122 mag and its long duration .
the mechanism giving rise to its huge luminosity is still unclear .
we performed optical spectroscopy and photometry of sn 2006gy at late time , @xmath2 400 days after the explosion , with the subaru / focas in a good seeing condition .
we carefully extracted the sn component , although there is an ambiguity because of the contamination by bright nucleus of the host galaxy .
we found that the sn faded by @xmath2 3 mag from @xmath2 200 to @xmath2 400 days after the explosion ( i.e. , by @xmath2 5 mag from peak to @xmath2 400 days ) in @xmath3 band .
the overall light curve is marginally consistent with the @xmath4ni heating model , although the flattening around 200 days suggests the optical flux declined more steeply between @xmath2 200 and @xmath2 400 days .
the late time spectrum was quite peculiar among all types of sne .
it showed many intermediate width ( @xmath5 km s@xmath6 fwhm ) emission lines , e.g. , [ ] , [ ] , and .
the absence of the broad [ ] 6300 , 6364 line and weakness of [ ] and [ ] lines compared with ir triplet would be explained by a moderately high electron density in the line emitting region .
this high density assumption seems to be consistent with the large amount of ejecta and low expansion velocity of sn 2006gy .
the h@xmath7 line luminosity was as small as @xmath8 erg s@xmath6 , being comparable with those of normal type ii sne at similar epochs .
our observation indicates that the strong csm interaction had almost finished by @xmath2 400 days .
if the late time optical flux is purely powered by radioactive decay , at least @xmath9 should be produced at the sn explosion . in the late phase spectrum
, there were several unusual emission lines at 74008800 and some of them might be due to ti or ni synthesized at the explosion . .
And you have already written the first three sentences of the full article: supernova ( sn ) 2006gy is an extremely luminous sn found by @xcite near the nucleus of the host galaxy ngc 1260 [ @xmath10 mag ] .
its absolute magnitude reaches @xmath2 @xmath11 mag ( ofek et al . 2007 ; smith et al .
2007 ) , being more luminous than typical type ia supernovae by a factor of @xmath12 ..
Please generate the next two sentences of the article | the sn was referred to as `` the most luminous sn '' at that time .
in addition to the high peak luminosity , the light curve ( lc ) of sn 2006gy evolves very slowly , peaking at @xmath13 70 days after the explosion ( hereafter , @xmath14 means time after the explosion ) . |
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