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11,100 |
Suppose that you have an abstract for a scientific paper: we have confirmed that the precursor star of the unusual supernova 1954j ( also known as variable 12 ) in ngc 2403 survived what appears to have been a super - outburst , similar to the 1843 great eruption of @xmath0 carinae in the galaxy .
the apparent survivor has changed little in brightness and color over the last eight years , and a keck spectrum reveals characteristics broadly similar to those of @xmath0 car .
this is further suggested by our identification of the actual outburst - surviving star in high - resolution images obtained with the advanced camera for surveys on the _ hubble space telescope_. we reveal this `` supernova impostor '' as a highly luminous ( @xmath1 mag ) , very massive ( @xmath2 ) eruptive star , now surrounded by a dusty ( @xmath3 mag ) nebula , similar to @xmath0 car s famous homunculus . .
And you have already written the first three sentences of the full article: the fate of the most massive stars in galaxies is not well understood .
such stars have been theoretically linked to black - hole formation , to some gamma - ray burst sources , and to early metal enrichment in the universe ( e.g. , umeda & nomoto 2003 ) . in principle , stars with initial masses @xmath4@xmath5 should pass through the red supergiant phase , or directly to the short - lived luminous blue variable ( lbv ) phase , on to the wolf - rayet ( wr ) phase ( e.g. , langer et al .
1994 ; stothers & chin 1996 ) , before exploding as supernovae ( sne ; e.g. , woosley , langer , & weaver 1993 ) or ending as `` collapsars '' ( e.g. , macfadyen & woosley 1999 ) . the great eruption of 1843 for @xmath0 carinae ( see davidson & humphreys 1997 ) , where the star s bolometric luminosity increased by a very large amount , demonstrated that some very massive stars go through spectacular eruptive phases of pre - sn mass ejection . this instability may play a role in shaping the appearance of the upper hertzsprung - russell ( h - r ) diagram ( humphreys & davidson 1994 ) ..
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however , lbvs , and particularly phenomenal cases such as @xmath0 car , are extremely rare ( humphreys & davidson 1994 ) ; isolating additional examples is therefore necessary for a better understanding of the evolution of very massive stars . the identification of a number of extragalactic objects as genuine sne ( strictly defined to be the violent destruction of a star at the end of its life ) has been questioned by several teams of investigators ( e.g. , goodrich et al
. 1989 ; filippenko et al . 1995 ; van dyk et al . 2000 , 2004 ; smith , humphreys , & gehrz 2001 ; wagner et al . 2004 ) .
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11,101 |
Suppose that you have an abstract for a scientific paper: the effect of histamine ( ha ) on the electric activities of purkinje cell ( pc ) is studied on the cerebellum slice .
we find that : ( 1 ) ha s main effect on pc is excitative ( 72.9% ) ; there are also a small amount of pc showing inhibitive ( 10.2% ) or no ( 16.9% ) response to ha .
( 2 ) different from the conventional opinion , ha s excitative effect on pc is mutually conducted by h1 and h2 receptors ; the antagonist for h1 receptor could weaken ha s excitative effect on pc , while the antagonist for h2 receptor could weaken or even block the excitative effect of ha on pc .
( 3 ) pc s reaction to ha is related to its intrinsic discharge frequency ; there exists a frequency at which pc is highly sensitive to ha , and well above this frequency pc becomes stable against ha .
these results indicate that the histaminergic afferent fibre can adjust pc s electric activities by releasing ha , and thereby influence the global function of the cerebellar cortex ; and that just like the @xmath0 region of cerebrum , cerebellum may also have some sort of characteristic frequency .
key words : cerebellar cortex ; purkinje cell ; histamine ; receptor ; cerebellum slice 2 .
And you have already written the first three sentences of the full article: cerebellum deserves more extensive studies than was conventionally realized .
historically , cerebellum was thought of as mainly a motor control organ , while recent researches reveal that it has many other functions , and it has more intimate connections to other parts of the brain @xcite .
histamine ( ha ) , a neurotransmitter or neuromodulator in the brain , plays an important role in the functions and interactions of various parts of the brain , and also in the studies of these functions and interactions ..
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for instance , the neuroanatamic researches revealed the existence of the hypothalamus - cerebellum histaminergic path @xcite , and shows that hypothalamus has great influence on the cerebellar activities and hence plays an important role in coordinating the functions of the body and viscera .
besides , ha has the possible role of controlling the cerebellar circulation , and ha receptors are also found in the neurons of the cerebellar cortex @xcite . cerebellum is made up of the outer dark matter ( cortex ) , inner white matter , and three pairs of deep nuclei lying in the heart of the white matter .
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11,102 |
Suppose that you have an abstract for a scientific paper: we present age and metallicities determinations based on narrow band continuum colors for the galaxies in the rich clusters a1185 and coma . using a new technique to extract luminosity - weighted age and [ fe / h ] values for non - star - forming galaxies , we find that both clusters have two separate populations based on these parameters .
one population is old ( @xmath0 11 gyrs ) with a distinct mass - metallicity relation .
the second population is slightly younger ( @xmath1 9 gyrs ) with lower metallicities and lower stellar masses .
we find detectable correlations between age and galaxy mass in both populations such that older galaxies are more massive and have higher mean metallicities , confirming previous work with line indices for the same type of galaxies in other clusters ( kelson 2006 , thomas 2005 ) . given the previously discovered correlation between galaxy mass and @xmath2/fe abundance ( a measure of the duration of initial star formation , denicolo 2005 , sanchez - blazquez 2006 ) , we interpret our age - metallicity correlations to imply that cluster galaxies are coeval with varying durations for their initial bursts .
our results imply shorter durations for higher mass galaxies , in contradiction to the predictions of classic galactic wind models . since we also find a clear mass - metallicity relation for these galaxies
, then we conclude that star formation was more efficient for higher mass galaxies , a scenario described under the inverse wind models ( matteucci 1994 ) . with respect to cluster environmental effects
, we find there is a significant correlation between galaxy mean age and distance from the cluster center , such that older galaxies inhabit the core .
this relationship would nominally support hierarchical scenarios of galaxy formation ( younger age in lower density regions ) ; however , environmental effects probably have larger signature in the sample and present - day galaxies are remnants from an epoch of quenching of initial star formation , which would....
And you have already written the first three sentences of the full article: the key to understanding the star formation history of galaxies is determining the age of their underlying stellar populations and the amount chemical evolution that those populations have undergone .
historically , these issues have been addressed separately and by morphological type .
for example , early - type galaxies are considered have the simplest modes of star formation , the oldest ages ( i.e. primordial ) and relatively passive evolution as indicated by their similarity in color , morphology and kinematic properties ( bernardi 2003 , tremonti 2004 , cool 2006 , smolcic 2006 ) ..
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very little current or recent star formation ( bernardi 2001 ) , plus low amounts of molecular gas ( huchtmeier , sage & henkel 1995 ) , reinforces the hypothesis that a majority of their stars have their origin at high redshift ( larson 1975 , kodama 1998 , jimenez 1999 , van dokkum & stanford 2003 ) .
work on the star formation history of galaxies is dominated by studies of rich clusters because 1 ) they are located in the same region of position and velocity space easing observational constraints , 2 ) they are easily detected in surveys at large redshift and are useful signposts for the study of evolutionary effects and 3 ) they are impacted by similar , if not complicated , environmental effects . since
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11,103 |
Suppose that you have an abstract for a scientific paper: we consider geometric flow equations for contracting and expanding normal velocities , including powers of the gauss curvature , @xmath0 , of the mean curvature , @xmath1 , and of the norm of the second fundamental form , @xmath2 , and ask whether - after appropriate rescaling - closed strictly convex surfaces converge to spheres . to prove this , many authors use certain functions of the principal curvatures , which we call maximum - principle functions .
we show when such functions cease to exist and exist , while presenting newly discovered maximum - principle functions . .
And you have already written the first three sentences of the full article: we consider the geometric flow equations @xmath3 and ask whether closed strictly convex @xmath4-dimensional surfaces @xmath5 in @xmath6 converge to round points or to spheres at @xmath7 .
the answer is affirmative for many normal velocities @xmath8 , including certain powers of the gauss curvature , @xmath0 , the mean curvature , @xmath1 , and the norm of the second fundamental form , @xmath2 . here , authors like b. andrews @xcite , o. schnrer @xcite , and f. schulze @xcite , use functions of the principal curvatures @xmath9 to show convergence to a round point or to spheres at @xmath7 . in @xcite , @xcite
, o. schnrer proposes a characterization of these functions . and.
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in this paper , we extend it to non - rational functions .
our definition of _ maximum - principle functions _ ( mpf ) now covers any such function @xmath9 that is known to far .
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11,104 |
Suppose that you have an abstract for a scientific paper: a pnjl model is built , in which the polyakov - loop potential is explicitly z@xmath0-symmetric in order to mimic a yang - mills theory with gauge group su(@xmath1 ) .
the physically expected large-@xmath1 and large-@xmath2 behaviours of the thermodynamic observables computed from the polyakov - loop potential are used to constrain its free parameters .
the effective potential is eventually u(1)-symmetric when @xmath1 is infinite .
light quark flavours are added by using a nambu - jona - lasinio ( njl ) model coupled to the polyakov loop ( the pnjl model ) , and the different phases of the resulting pnjl model are discussed in t hooft s large-@xmath1 limit .
three phases are found , in agreement with previous studies resorting to effective approaches of qcd .
when the temperature @xmath2 is larger than some deconfinement temperature @xmath3 , the system is in a deconfined , chirally symmetric , phase for any quark chemical potential @xmath4 . when @xmath5 however , the system is in a confined phase in which chiral symmetry is either broken or not . the critical line @xmath6 , signalling the restoration of chiral symmetry , has the same qualitative features than what can be obtained within a standard @xmath7 pnjl model . .
And you have already written the first three sentences of the full article: the structure of the qcd phase diagram is intimately related to our understanding of fundamental features of qcd , like for example confinement dynamics and chiral symmetry breaking , and to their interplay with in - medium effects like a nonzero temperature or quark density .
this is the reason why a lot of effort is devoted to study this field , either on the theoretical side , to which the present work belongs , or on the experimental side through heavy - ion - collision experiments . among the various effective frameworks used to study the qcd phase diagram ( see _ e.g. _ the review @xcite ) , we will mostly focus on two of them : polyakov - loop effective models for the pure gauge part of qcd , and the nambu - jona - lasinio ( njl ) model for the quark part .
the polyakov loop is defined as @xmath8 in which @xmath9 is the path - ordering , @xmath10 the strong coupling constant , @xmath11 the temporal component of the yang - mills field , @xmath12 the generators of the gauge algebra , and @xmath2 the temperature ..
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the integral runs on the compactified timelike dimension .
the polyakov loop is a precious tool to study the phase structure of a given yang - mills theory since @xmath13 @xmath14 when the theory is in a ( de)confined phase @xcite .
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11,105 |
Suppose that you have an abstract for a scientific paper: microphase separated structure consisting of the periodic alternation of the layers of stretched homopolymer chains surrounded by perpendicularly oriented oligomeric ( surfactant ) tails is studied for the systems with strong ionic ) as well as weak ( hydrogen ) interaction .
our approach is based on the fact that the structure period is determined by alternating associations between the head groups of the oligomer molecules and interacting groups of the homopolymer chains .
distribution of oligomers along the homopolymer chains is described by the effective equation of motion with the segment number playing the role of time . as a result ,
experimentally observed temperature dependence of the structure period , as well as the dependence of the point of order disorder transition are determined as functions of the oligomeric fraction . .
And you have already written the first three sentences of the full article: various mesomorphic structures can be prepared using the strong ( ionic ) or weak ( hydrogen ) bonding , respectively , between homopolymers and head functionalized oligomers or surfactants @xcite .
the interaction between the head group of the oligomeric molecule and suitable groups on the homopolymer chain , on the one hand , and unfavorable polar nonpolar interactions between the non polar tail of the oligomer and the rest of the system , on the other one , can cause the microphase separation .
the latter effect results in a periodic alternation of the layers of stretched homopolymer chains surrounded by perpendicularly oriented oligomeric tails as it is shown in figure 1 ..
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an example of the ionically bonded system is represented by the homopolymer - oligomer mixture of atactic poly(4-vinyl pyridine ) ( p4vp ) and dodecyl benzene sulfonic acid ( dbsa ) where due to a very strong interaction the microphase separation is realized over the whole temperature region @xcite .
the peculiarity of the systems of this kind is an increasing long space period @xmath0 as a function of the oligomeric fraction @xmath1 defined as the number of the oligomeric ( dbsa ) molecules per one pyridine ring ( see figure 2 ) .
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11,106 |
Suppose that you have an abstract for a scientific paper: we have measured dispersions of spin - flip waves and spin - flip single - particle excitations of a spin polarized two - dimensional electron gas in a cd@xmath0mn@xmath1te quantum well using resonant raman scattering .
we find the energy of the spin - flip wave to be below the spin - flip single particle excitation continuum , a contradiction to the theory of spin waves in diluted magnetic semiconductors put forth in [ phys .
rev .
b * 70 * 045205 ( 2004 ) ] .
we show that the inclusion of terms accounting for the coulomb interaction between carriers in the spin wave propagator leads to an agreement with our experimental results .
the dominant coulomb contribution leads to an overall red shift of the mixed electron - mn spin modes while the dynamical coupling between mn ions results in a small blue shift .
we provide a simulated model system which shows the reverse situation but at an extremely large magnetic field . .
And you have already written the first three sentences of the full article: collective spin dynamics in dilute magnetic semiconductors ( dms ) is an active field under intense investigations.@xcite this field provides an insight into the origins of carrier - induced ferromagnetism in semiconductors @xcite and an understanding of particular features of the dms @xcite due to the presence of two spin sub - systems that are dynamically coupled via coulomb - exchange interaction : that of the itinerant carrier and that of the localized magnetic impurities . as an example of these features , the transverse spin excitation spectrum has been theoretically found to be composed of three types of excitations .
these are : two collective excitations corresponding to itinerant and localized spins precessing in phase or out of phase to each other , and single - particle ( or stoner - like ) excitations of the itinerant carriers.@xcite the in - phase collective mode is the goldstone - like mode .
the out of phase mode has a dominant contribution from the itinerant carrier subsystem.@xcite experimental evidences of the entire spectrum in ferromagnetic dms like gamnas is not available ..
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reported so far are features related to the zone - center in phase mode , dominated by the mn spin precession , its dynamics@xcite and its ferromagnetic resonance.@xcite we find no experimental data available for the out of phase mode .
indeed , ferromagnetism in gamnas systems requires a high mn concentration , which destroys the quality of the crystal potential and smooths out all optical resonances . to gain more insight into the dms spin excitation spectrum , cd@xmath0mn@xmath1te doped quantum wells are a very good alternative as they are clean and efficient to capture the general properties of the collective spin dynamics in dms materials .
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11,107 |
Suppose that you have an abstract for a scientific paper: we consider recent progress in algorithms for generating gauge field configurations that include the dynamical effects of light fermions .
we survey what has been achieved in recent state - of - the - art computations , and examine the trade - offs between performance and control of systematic errors .
we briefly review the use of polynomial and rational approximations in hybrid monte carlo algorithms , and some of the theory of on - shell chiral fermions on the lattice .
this provides a theoretical framework within which we compare algorithmic alternatives for their implementation ; and again we examine the trade - offs between speed and error control . .
And you have already written the first three sentences of the full article: the aim of this review is to provide a snapshot of the present status of dynamical fermion simulations , both as regards their performance and the possible sources of systematic errors that are not fully under control , as well as an introduction to some of the algorithmic ideas that are currently being investigated .
as the goal is to be pedagogical rather than exhaustive we do not attempt to summarise all of the algorithmic talks that were presented at this conference . in
we consider the present state of large - scale dynamical fermion computations , comparing their costs and their control of systematic errors ..
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this leads us to consider the issue of the locality of using fractional powers of the fermion determinant in .
in we consider various algorithms for introducing `` fat links '' in a differentiable way . in
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11,108 |
Suppose that you have an abstract for a scientific paper: understanding quantum dynamics in a two - dimensional bose - einstein condensate ( bec ) relies on understanding how vortices interact with each others microscopically and with local imperfections of the potential which confines the condensate . within a system consisting of many vortices ,
the trajectory of a vortex - antivortex pair is often scattered by a third vortex , an effect previously characterised .
however , the natural question remains as to how much of this effect is due to the velocity induced by this third vortex and how much is due to the density inhomogeneity which it introduces . in this work
, we describe the various qualitative scenarios which occur when a vortex - antivortex pair interacts with a smooth density impurity whose profile is identical to that of a vortex but lacks the circulation around it . .
And you have already written the first three sentences of the full article: in a recent paper @xcite , smirnov & smirnov have studied the scattering of two - dimensional ( 2d ) vortex - antivortex pairs and solitons by a single quantum vortex in a homogeneous atomic bose - einstein condensate .
they found that the pair is scattered over large angles radiating sound waves , in agreement with earlier calculations @xcite .
this scattering process is important because it lies at the heart of the dynamics of 2d quantum turbulence , a problem which is currently attracting experimental and theoretical attention @xcite ..
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our understanding of the turbulent motion of many interacting vortices is based on recognizing the most elementary interactions , such as the interaction of a vortex with another vortex of the same or opposite sign ( resulting respectively in rotational or translation motion of the pair ) .
similary , we would like to recognize the possible elementary interactions between a vortex and a large density perturbation induced by the dynamics of vortices by external means .
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11,109 |
Suppose that you have an abstract for a scientific paper: vertex separation minimization problem ( vsmp ) consists of finding a layout of a graph @xmath0 which minimizes the maximum vertex cut or separation of a layout .
it is an np - complete problem in general for which metaheuristic techniques can be applied to find near optimal solution .
vsmp has applications in vlsi design , graph drawing and computer language compiler design .
vsmp is polynomially solvable for grids , trees , permutation graphs and cographs .
construction heuristics play a very important role in the metaheuristic techniques as they are responsible for generating initial solutions which lead to fast convergence . in this paper , we have proposed three construction heuristics _ _ h__1 , _ _ h__2 and _ _ h__3 and performed experiments on grids , small graphs , trees and harwell boeing graphs , totaling 248 instances of graphs .
experiments reveal that _ _
h__1 , _ _ h__2 and _ _ h__3 are able to achieve best results for 88.71% , 43.5% and 37.1% of the total instances respectively while the best construction heuristic in the literature achieves the best solution for 39.9% of the total instances .
we have also compared the results with the state - of - the - art metaheuristic gvns and observed that the proposed construction heuristics improves the results for some of the input instances .
it was found that gvns obtained best results for 82.9% instances of all input instances and the heuristic _ _
h__1 obtained best results for 82.3% of all input instances . .
And you have already written the first three sentences of the full article: graph layout problems are a class of combinatorial optimization problems whose goal is to find a layout of an input graph _
g _ to optimize a certain objective function . a linear layout or layout of an undirected graph @xmath1 , where @xmath2 is the bijective function @xmath3=\{1,2,\dots,\emph{n}\}$ ] .
set of all layouts is denoted by @xmath4 ..
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a region in layout is defined as the area between two consecutive vertices in the layout .
vertex separation minimization problem ( vsmp ) is to find a layout @xmath5 of a graph @xmath0 which minimizes the vertex separation ( _ vs _ ) where @xmath6}\delta(i,\varphi , g)$ ] for a layout @xmath7 where , @xmath8 , @xmath9 and @xmath10 @xcite .
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11,110 |
Suppose that you have an abstract for a scientific paper: an exact solution to the friedmann equations with a string inspired phantom scalar matter field is constructed and the absence of the `` big rip '' singularity is shown explicitly .
the notable features of the concerned model are a ghost sign of the kinetic term and a special polynomial form of the effective tachyon potential .
the constructed solution is stable with respect to small fluctuations of the initial conditions and special deviations of the form of the potential . .
And you have already written the first three sentences of the full article: the combined analysis of the type ia supernovae , galaxy clusters measurements and wmap ( wilkinson microwave anisotropy probe ) data brings out clearly an evidence of the accelerated expansion of the universe @xcite-@xcite .
the cosmological acceleration strongly indicates that the present day universe is dominated by a smoothly distributed slowly varying cosmic fluid with a negative pressure , the so - called dark energy @xcite-@xcite ( alternative approaches are presented , for example , in @xcite ) . to specify different types of cosmic fluids one
usually uses a phenomenological relation between the pressure density @xmath0 and the energy density @xmath1 , corresponding to each component of fluid @xmath2 where @xmath3 is the equation - of - state parameter or , for short , the state parameter . a component with negative.
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@xmath3 corresponds to the dark energy .
contemporary experiments , including wmap , give strong support that at present time the dark energy state parameter is close to @xmath4 @xcite , @xcite-@xcite .
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11,111 |
Suppose that you have an abstract for a scientific paper: we investigate some significant properties of multi - band superconductors .
they are time - reversal symmetry breaking , chirality and fractional quantum flux vortices in three - band superconductors .
the bcs ( bardeen - cooper - schrieffer ) gap equation has a solution with time - reversal symmetry breaking in some cases .
we derive the ginzburg - landau free energy from the bcs microscopic theory .
the frustrating pairing interaction among fermi surfaces leads to a state with broken time - reversal symmetry , that is , a chiral solution .
the ginzburg - landau equation for three - component superconductors leads to a double sine - gordon model .
a kink solution exists to this equation as in the conventional sine - gordon model . in the chiral region of the double sine - gordon model ,
an inequality of bogomolnyi type holds , and fractional-@xmath0 kink solutions exist with the topological charge @xmath1 .
this yields multi - vortex bound states in three - band superconductors . .
And you have already written the first three sentences of the full article: since the discovery of oxypnictides lafeaso@xmath2f@xmath3@xcite , bafe@xmath4as@xmath4@xcite , lifeas@xcite and fe@xmath5se@xcite , the fe pnictides high - temperature superconductors have attracted extensive attention .
there are numerous experimental studies regarding the electronic states of the new family of iron - based superconductor@xcite .
the undoped samples exhibit the antiferromagnetic transition@xcite , and show the superconducting transition with electron doping@xcite ..
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the band structure calculations indicate that the fermi surfaces are composed of two hole - like cylinders around @xmath6 , a three - dimensional fermi surface , and two electron - like cylinder around m for lafeaso@xcite .
this family of iron pnictides is characterized by multi fermi surfaces , and theoretical studies have been based on multi - band models with electronic interactions@xcite .
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11,112 |
Suppose that you have an abstract for a scientific paper: we review the kinematics of a neutrino beam in the idealized case where the parent mesons momenta are parallel , but without any other approximation .
this reveals several interesting features , in particular in the off - axis case , which are hidden by the approximations made in a previous treatment . .
And you have already written the first three sentences of the full article: the kinematics of an off - axis neutrino beam in the approximation where the parent meson beam is divergenceless was posed as a problem to the student in these archives a long time ago .
however , the author of @xcite seems not to have noticed that the problem is amenable to an exact treatment which reveals interesting aspects hidden by the approximations he uses . in this note , we show how to implement exactly the lorentz transformation in the differential ( angle , energy ) distribution and we exhibit some features of the results .
+ among others , it is shown that a sizeable part of the flux at a given lab angle comes from neutrinos going backwards in the center of mass frame of the decaying meson ..
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given the approximations made in @xcite , it is not clear that they are taken into account in the results presented .
how this might have a bearing on the calculations of neutrino fluxes being performed with more realistic divergent meson beams in the preparation of upcoming experiments is unknown to the present author .
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11,113 |
Suppose that you have an abstract for a scientific paper: the type ia supernova ( sn ia ) 2016coj in ngc 4125 ( redshift @xmath0 ) was discovered by the lick observatory supernova search 4.9 days after the fitted first - light time ( fflt ; 11.1 days before @xmath1-band maximum ) .
our first detection ( pre - discovery ) is merely @xmath2 day after the fflt , making sn 2016coj one of the earliest known detections of a sn ia .
a spectrum was taken only 3.7 hr after discovery ( 5.0 days after the fflt ) and classified as a normal sn ia .
we performed high - quality photometry , low- and high - resolution spectroscopy , and spectropolarimetry , finding that sn 2016coj is a spectroscopically normal sn ia , but with a high velocity of @xmath36355 ( @xmath4kms@xmath5 around peak brightness )
. the @xmath36355 velocity evolution can be well fit by a broken - power - law function for up to a month after the fflt .
sn 2016coj has a normal peak luminosity ( @xmath6 mag ) , and it reaches a @xmath1-band maximum @xmath7 16.0 d after the fflt .
we estimate there to be low host - galaxy extinction based on the absence of na i d absorption lines in our low- and high - resolution spectra .
the spectropolarimetric data exhibit weak polarization in the continuum , but the line polarization is quite strong ( @xmath8 ) at peak brightness . .
And you have already written the first three sentences of the full article: type ia supernovae ( sne ia ; see filippenko 1997 for a review of supernova classification ) are the thermonuclear runaway explosions of carbon / oxygen white dwarfs ( see , e.g. , hillebrandt & niemeyer 2000 for a review ) .
they can be used as standardizable candles with many important applications , including measurements of the expansion rate of the universe ( riess et al .
1998 ; perlmutter et al . 1999 ) ..
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two general scenarios are favored as the progenitor system for sne ia .
one is the single - degenrate model ( hoyle & fowler 1960 ; hachisu et al .
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11,114 |
Suppose that you have an abstract for a scientific paper: the engineering through strain of material properties is very interesting for a wide list of applications , specially for atomically thin membranes made of mos@xmath0 because of its high young modulus and fracture strength .
the modification of the electronic structure and electronic transport under tensile and compressive strain of mos@xmath0 and other transition metal dichalcogenides has been predicted by _
ab initio _ calculations in several works .
a transition from semiconductor to metallic transport has been predicted for single and few layer mos@xmath0 . in this article
we present the observation of this effect on a few layer mos@xmath0 ribbon under a maximum uniaxial tensile strain of 0.14 .
experimental data are accompanied with _
ab initio _ calculations showing that uniaxial strain on few layer mos@xmath0 provokes the closing of the energy band - gap .
molybdenum disulphide , mos@xmath0 , is a layered crystalline solid with an hexagonal structure similar to graphene .
single layer mos@xmath0 is formed by a plane of mo atoms sandwiched and covalently bonded to two planes of s atoms .
few layer and bulk mos@xmath0 is formed by successive stacking of this hexagonal structure through vdw forces . in a bulk form , mos@xmath0 is an indirect semiconductor with energy gap eg= while its single layer counterpart shows a direct transition at the k point with eg=. this material among other transition metal dichalcogenides ( tmds ) has been widely studied in the last years because of their outstanding optical , mechanical and electrical properties along very strong electro - mechanical and opto - mechanical coupling@xcite . in particular
, mos@xmath0 has been suggested to show a transition from semiconductor to metal under mechanical strain@xcite and not only for monolayer mos@xmath0 but also for few - layer mos@xmath0 and even bulk@xcite .
although several studies based on _ ab initio _ calculations have predicted this particular effect no experimental validation has been published....
And you have already written the first three sentences of the full article: i.n . and m.l.s .
contributed equally to this work .
the authors gratefully acknowledge w. venstra for useful discussion , a. di michele and p. sassi for raman analysis ..
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the authors acknowledge financial support from the european commission ( fpvii , grant agreement no : 318287 , landauer ) .
21ifxundefined [ 1 ] ifx#1 ifnum [ 1 ] # 1firstoftwo secondoftwo ifx [ 1 ] # 1firstoftwo secondoftwo `` `` # 1''''@noop [ 0]secondoftwosanitize@url [ 0 ]
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11,115 |
Suppose that you have an abstract for a scientific paper: discovering the higgs boson is one of the primary goals of both the tevatron and the large hadron collider ( lhc ) .
the present status of the higgs search is reviewed and future prospects for discovery at the tevatron and lhc are considered .
this talk focuses primarily on the higgs boson of the standard model and its minimal supersymmetric extension .
theoretical expectations for the higgs boson and its phenomenological consequences are examined .
scipp-10/17 + november , 2010 + .
And you have already written the first three sentences of the full article: the origin of electroweak symmetry breaking and the mechanism that generates the masses of the known fundamental particles is one of the central challenges of particle physics .
the higgs mechanism @xcite in its most general form can be used to explain the observed masses of the @xmath0 and @xmath1 bosons as a consequence of three goldstone bosons ( @xmath2 and @xmath3 ) that end up as the longitudinal components of the massive gauge bosons .
these goldstone bosons are generated by the underlying dynamics responsible for electroweak symmetry breaking ..
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however , the fundamental nature of this dynamics is still unknown .
two broad classes of electroweak symmetry breaking mechanisms have been pursued theoretically . in one class of theories ,
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11,116 |
Suppose that you have an abstract for a scientific paper: we discuss the effect of the finite size of galaxies on estimating small - scale relative pairwise peculiar velocity dispersions from the cosmic virial theorem ( cvt ) .
specifically we evaluate the effect by incorporating the finite core radius @xmath0 in the two - point correlation function of mass , i.e. @xmath1 and the effective gravitational force softening @xmath2 on small scales .
we analytically obtain the lowest - order correction term for @xmath3 which is in quantitative agreement with the full numerical evaluation . with a nonzero @xmath2 and/or
@xmath0 the cosmic virial theorem is no longer limited to the case of @xmath4 .
we present accurate fitting formulae for the cvt predicted pairwise velocity dispersion for the case of @xmath5 . compared with the idealistic point - mass approximation ( @xmath6 )
, the finite size effect can significantly reduce the small - scale velocity dispersions of galaxies at scales much larger than @xmath2 and @xmath0 . even without considering the finite size of galaxies , nonzero values for @xmath0
are generally expected , for instance , for cold dark matter ( cdm ) models with a scale - invariant primordial spectrum . for these cdm models ,
a reasonable force softening @xmath7 would have rather tiny effect .
we present the cvt predictions for the small - scale pairwise velocity dispersion in the cdm models normalized by the cobe observation .
the implication of our results for confrontation of observations of galaxy pair - wise velocity dispersions and theoretical predictions of the cvt is also discussed . # 1 ( # 1 )
# 1\ { # 1 } # 1 # 1#1 0.1 in the university of tokyo + 0.1 in research center for the early universe + resceu-33/96 + utap-240/96 + .
And you have already written the first three sentences of the full article: the three - dimensional distribution of galaxies observed in redshift surveys differs from the true one since the distance to each galaxy can not be determined by its redshift @xmath8 only ; for @xmath9 the peculiar velocity of galaxies , typically @xmath10 , contaminates the true recession velocity of the hubble flow ( e.g. , davis & peebles 1983 ; kaiser 1987 ; hamilton 1992 ) , while the true distance for objects at @xmath11 sensitively depends on the ( unknown and thus assumed ) cosmological parameters .
this hampers the effort to understand the true distribution of large - scale structure of the universe .
nevertheless such redshift - space distortion effects are quite useful since through the detailed theoretical modeling , one can derive the peculiar velocity dispersions of galaxies as a function of separation ( davis & peebles 1983 ) , and also can infer the cosmological density parameter @xmath12 and the dimensionless cosmological constant @xmath13 , for instance ( ballinger , peacock & heavens 1996 ; matsubara & suto 1996 ; suto & matsubara 1996 ) . theoretically , a conventional tool to predict small - scale relative pairwise peculiar velocity dispersions is the cosmic virial theorem ( peebles 1976 ; hereafter cvt ) . in its simplest form , the prediction is based on the idealistic assumption that galaxies are treated as point particles . as peebles ( 1976 ) remarked , however , the finite size effect is very significant on scale @xmath14 even if one considers a radius of @xmath15 for typical galactic halos . in this paper.
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we explore this realistic effect in more details and discuss its important impact on the application of the cvt to real observations .
we will also give reliable predictions for the small - scale velocity dispersions of galaxies in cobe normalized cdm models .
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Suppose that you have an abstract for a scientific paper: the long - term optical and near infrared monitoring observations for a type 1 active galactic nucleus ngc 4151 were carried out for six years from 2001 to 2006 by using the magnum telescope , and delayed response of flux variations in the @xmath0 band to those in the @xmath1 band was clearly detected .
based on cross correlation analysis , we precisely measured a lag time @xmath2 for eight separate periods , and we found that @xmath2 is not constant changing between 30 and 70 d during the monitoring period . since @xmath2 is the light travel time from the central energy source out to the surrounding dust torus , this is the first convincing evidence that the inner radius of dust torus did change in an individual agn . in order to relate such a change of @xmath2 with a change of agn luminosity @xmath3 , we presented a method of taking an average of the observed @xmath4-band fluxes that corresponds to the measured value of @xmath2 , and we found that the time - changing track of ngc 4151 in the @xmath2 versus @xmath3 diagram during the monitoring period deviates from the relation of @xmath5 expected from dust reverberation .
this result , combined with the elapsed time from period to period for which @xmath2 was measured , indicates that the timescale of dust formation is about one year , which should be taken into account as a new constraint in future studies of dust evolution in agns . .
And you have already written the first three sentences of the full article: the unified model of active galactic nuclei ( agns ) @xcite assumes the existence of dust torus that surrounds the central hierarchical structure consisting of a super massive black hole , an accretion disk , and a broad line region ( blr ) .
the dust grains in the torus absorb the uv / optical continuum emission from the accretion disk and re - radiate in the near infrared ( ir ) wavelength region with some lag time corresponding to the light travel time from the accretion disk to the inner radius of dust torus .
since the heated dust eventually sublimates at a constant temperature of 1500 - 1800k , a more luminous agn should have a larger dust torus and hence a larger lag time , yielding a correlation of @xmath5 between lag time @xmath2 and agn luminosity @xmath3 @xcite ..
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in fact , based on the long - term multicolor monitoring data from the magnum project @xcite and available archival data , @xcite recently reported such a correlation from a sample of agns spanning a wide range of absolute @xmath4-magnitude from @xmath6 to @xmath7 .
the optical luminosity is a good indicator of uv luminosity , because their variations are well synchronized with each other @xcite .
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Suppose that you have an abstract for a scientific paper: we show that the energy gap induced by ferromagnetically aligned magnetic impurities on the surface of a topological insulator can be filled , due to scattering off the non - magnetic potential of the impurities . in both a continuum surface model and a three - dimensional tight - binding lattice model
, we find that the energy gap disappears already at weak potential scattering as impurity resonances add spectral weight at the dirac point .
this can help explain seemingly contradictory experimental results as to the existence of a gap .
the recent discovery of topological insulators ( tis ) @xcite has led to exciting possibilities for producing electronically engineered states .
tis are bulk insulators but host metallic surface states with a dirac - like dispersion @xcite .
the momentum - spin locking in the surface states @xcite offers unique technological capabilities , especially if an energy gap can be created .
a gap in the ti surface states can be generated by time - reversal breaking perturbations and one of the currently most discussed approaches for engineering a gap is magnetic doping @xcite .
the idea is that ferromagnetically ordered impurities will produce a net magnetic field , which then gaps the ti surface states @xcite . beyond an energy gap
, this would also give rise to multiple other exotic phenomena , such as the anomalous hall effect recently observed @xcite .
however , despite a multitude of recent experimental studies , evidence for a gap in the ti surface states from magnetic doping remains controversial .
both angle - resolved photoemission spectroscopy ( arpes ) and scanning tunneling spectroscopy ( sts ) measurements have reported the presence of an energy gap @xcite , while other similar studies have found no gap @xcite .
interestingly , several studies have even reported no significant difference between magnetic and non - magnetic surface impurities @xcite .
the key assumption , when expecting an energy gap from magnetic impurities , is that....
And you have already written the first three sentences of the full article: we first consider an effective continuum model of the surface states of a ti and their coupling to local magnetic impurities using the hamiltonian @xmath6 here @xmath7 is the fermi velocity of the surface states , @xmath8 denotes the vector of pauli matrices , and @xmath9 is the electron annihilation spinor at momentum @xmath10 .
the magnetic impurities are modeled by the total scattering potential @xmath11 , which includes both scattering off a potential @xmath3 , with the identity matrix @xmath12 , and magnetic moment @xmath13 , both acting as point defects at positions @xmath14 . for simplicity ,
since the quantum nature of the spins is not crucial , we use large spin moments @xmath15 and weak couplings @xmath16 , requiring @xmath17 constant , such that the impurity spins can be treated as classical . with the spin of the surface states oriented within the @xmath18-plane in @xmath19 , a magnetic field along.
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the @xmath20-direction gaps the surface spectrum at the dirac point , as it adds a term proportional to @xmath21 @xcite .
single magnetic impurities with moment along @xmath20 ( with potential scattering ignored ) and with a finite spatial extent have also been shown to give an effective local gap @xcite , while a single point - like magnetic impurity results in no incipient gap @xcite . for finite concentration of point - like magnetic impurities
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Suppose that you have an abstract for a scientific paper: we discuss how the geometry of @xmath0-@xmath1 branes may be related to gromov - witten theory of calabi - yau threefolds . .
And you have already written the first three sentences of the full article: topological sigma models , first put forward by witten @xcite , have long fascinated a number of theoretical physicists and mathematicians .
most remarkably , the task of summing up worldsheet instantons is nowadays elegantly formulated by the theory of gromov - witten invariants .
explicit computations of them are still being actively pursued ..
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it goes without saying that among many possible target spaces calabi - yau threefolds have played distinguished roles and are of lasting interest to string theorists . since the initial appreciation of the significance of d - branes there has been the lingering hope that the gromov - witten theory of calabi - yau threefolds might be completely rewritten in the language of bps d - branes .
this contribution is intended for explaining the picture which , to my eye , looks particularly attractive in this regard .
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Suppose that you have an abstract for a scientific paper: the creation of synthetic systems that emulate the defining properties of living matter , such as motility , gradient - sensing , signalling and replication , is a grand challenge of biomimetics .
such imitations of life crucially contain active components that transform chemical energy into directed motion .
these artificial realizations of motility point in the direction of a new paradigm in engineering , through the design of emergent behavior by manipulating properties at the scale of the individual components .
catalytic colloidal swimmers are a particularly promising example of such systems . here
we present a comprehensive theoretical description of gradient - sensing of an individual swimmer , leading controllably to chemotactic or anti - chemotactic behavior , and use it to construct a framework for studying their collective behavior .
we find that both the positional and the orientational degrees of freedom of the active colloids can exhibit condensation , signalling formation of clusters and asters .
the kinetics of catalysis introduces a natural control parameter for the range of the interaction mediated by the diffusing chemical species . for various regimes in parameter space in the long - ranged limit
our system displays precise analogs to gravitational collapse , plasma oscillations and electrostatic screening .
we present prescriptions for how to tune the surface properties of the colloids during fabrication to achieve each type of behavior . .
And you have already written the first three sentences of the full article: dynamic self - organization of motile components can be observed in a wide range of length scales , from bird flocks @xcite to bacterial colonies @xcite and assemblies of motor and structural proteins @xcite .
the fascination with these phenomena has naturally inspired researchers to use a physical understanding of motility to engineer complex emergent behaviors in model systems that promise revolutionary advance in technological applications if combined with other novel biomimetic functions , such as signal processing and decision making @xcite , or replication @xcite .
symmetry - based phenomenological theories , coarse - grained or particle - based @xcite offer a guide to the rich possibilities immanent in self - driven systems , but designing a system requires a bottom - up approach ..
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biological components pose inevitable limitations on this task , while chemical @xcite , mechanical @xcite or externally actuated @xcite imitations appear more promising .
in addition to motility , living organisms have developed mechanisms that allow them to orient their motion in response to chemical gradients , and send signals to recruit or repel others @xcite .
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Suppose that you have an abstract for a scientific paper: a discussion is presented of the manner in which uncertainties in parton distributions and related quantities are determined .
one of the central problems is the criteria used to judge what variation of the parameters describing a set of partons is acceptable within the context of a global fit .
various ways of addressing this question are outlined . .
And you have already written the first three sentences of the full article: the procedure of determining parton distributions by so - called global fits to data , mainly structure functions , is long established @xcite-@xcite
. however , it is a rather more recent development to try to determine the errors on these distributions at the same time .
this has come about for a number of reasons ..
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firstly , the sheer amount of data ( full references in @xcite ) sensitive to various parton distributions , and the precision of this data , has become such that an accurate determination of all parton distributions is possible ( with some problems only in difficult to reach regions of phase space , e.g. @xmath0 very near to 1 ) .
secondly , the understanding of the experimental errors on this data has reached a new level of sophistication , with the systematic errors being understood far better in terms of their separate sources and correlations .
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Suppose that you have an abstract for a scientific paper: ground states of the frustrated spin-1 ising - heisenberg two - leg ladder with heisenberg intra - rung coupling and only ising interaction along legs and diagonals are rigorously found by taking advantage of local conservation of the total spin on each rung .
the constructed ground - state phase diagram of the frustrated spin-1 ising - heisenberg ladder is then compared with the analogous phase diagram of the fully quantum spin-1 heisenberg two - leg ladder obtained by density matrix renormalization group ( dmrg ) calculations .
it is demonstrated that both investigated spin models exhibit quite similar magnetization scenarios , which involve intermediate plateaux at one - quarter , one - half and three - quarters of the saturation magnetization . .
And you have already written the first three sentences of the full article: over the last few decades , quantum spin ladders have been actively studied mainly in connection with spin - liquid behaviour , quantum critical points and superconductivity under hole doping of some cuprates ( see ref . [ ] for a review ) . in particular , the frustrated spin-1/2 heisenberg two - leg ladder exhibits a striking dimerized ground state [ ] and a low - temperature magnetization process with an intermediate plateau and magnetization jumps [ ] .
another challenging topic of current research interest consists of the theoretical investigation of related models such as the quantum spin-1 heisenberg two - leg ladder [ ] .
the main goal of the present work is to find the exact ground states of a simpler spin-1 ising - heisenberg ladder and to contrast them with the respective ground states of the pure quantum spin-1 heisenberg ladder ..
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note that the former model is analytically tractable using the procedure developed in refs .
[ ] and it brings insight into the relevant behaviour of the latter not fully integrable model .
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Suppose that you have an abstract for a scientific paper: equilibrium equations in the form of complementarity conditions often appear as constraints in optimization problems .
problems of this type are commonly referred to as mathematical programs with complementarity constraints ( mpccs ) . a popular method for solving mpccs
is the penalty interior - point algorithm ( pipa ) .
this paper presents a small example for which pipa converges to a nonstationary point , providing a counterexample to the established theory .
the reasons for this adverse behavior are discussed .
* keywords : * nonlinear programming , interior - point methods , pipa , mpec , mpcc , equilibrium constraints .
* ams - msc2000 : * 90c30 , 90c33 , 90c51 , 49m37 , 65k10 . .
And you have already written the first three sentences of the full article: equilibrium equations in the form of complementarity conditions often appear as constraints in optimization problems .
problems of this type are commonly referred to as mathematical programs with complementarity constraints ( mpccs ) , and arise in many engineering and economic applications ; see the survey @xcite and the monographs @xcite for further references .
the growing collections of test problems @xcite indicate that this an important area ..
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mpccs can be expressed in general as [ mpec ] ll & f(x , y , w , z ) + & x x + & f(x , y , w , z ) = 0 + & 0 y w 0 , where @xmath0 is a polyhedral set , @xmath1 and @xmath2 are twice continuously differentiable functions , and @xmath3 .
the complementarity constraint @xmath4 means that either a component of @xmath5 is zero , or the corresponding component of @xmath6 is zero , which implies that @xmath7 .
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Suppose that you have an abstract for a scientific paper: the notion of fidelity in quantum information science has been recently applied to analyze quantum phase transitions from the viewpoint of the ground - state ( gs ) overlap for various many - body systems . in this work ,
we unveil the intrinsic relation between the gs fidelity and the derivatives of gs energy and find that they play equivalent role in identifying the quantum phase transition .
the general connection between the two approaches enables us to understand the different singularity and scaling behaviors of fidelity exhibited in various systems on general grounds .
our general conclusions are illustrated via several quantum spin models which exhibit different kinds of qpts . .
And you have already written the first three sentences of the full article: quantum phase transitions ( qpts ) that happened at the zero temperature is purely a phenomenon of ground state ( gs ) transition driven by external parameters .
traditionally , qpts are described in terms of order parameter and symmetry breaking within the landau - ginzburg paradigm which have been extensively studied in condensed matter physics @xcite . in recent years
, qpt has also attracted a lot of attention in quantum - information science @xcite , in which one of the research focus is the role of quantum entanglement in characterizing qpts @xcite ..
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more recently , another concept in quantum information science , i.e. , the fidelity has been put forward to identify qpts from the perspective of the gs wave functions @xcite .
the gs fidelity is defined as the overlap between two ground states with only slightly different values of the external parameters @xcite and thus is a pure geometrical quantity . since no a priori knowledge of the order parameter is needed , the fidelity might be a potential universal criteria for characterizing the qpts @xcite .
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Suppose that you have an abstract for a scientific paper: we report new spectroscopic and photometric observations of the main - sequence , detached , eccentric , double - lined eclipsing binary ( @xmath0 days , @xmath1 ) . using these observations together with existing measurements we determine the component masses and radii to better than 1% precision : @xmath2 , @xmath3 , @xmath4 , and @xmath5 .
the nearly identical b9.5 stars have estimated temperatures of @xmath6 k and @xmath7 k. a comparison of these properties with current stellar evolution models shows excellent agreement at an age of about 190 myr and @xmath8 } \approx -0.18 $ ] .
both components are found to be rotating at the pseudo - synchronous rate .
the system displays a slow periastron advance that is dominated by general relativity ( gr ) , and has previously been claimed to be slower than predicted by theory .
our new measurement , @xmath9 deg century@xmath10 , has an 88% contribution from gr and agrees with the expected rate within the uncertainties .
we also clarify the use of the gravity darkening coefficients in the light - curve fitting program ebop , a version of which we use here . .
And you have already written the first three sentences of the full article: ( also hd 331102 , bd+30 3704 , tyc 2656 - 3703 - 1 , @xmath11 ) is an early type ( b9.5+b9.5 ) detached , eccentric , double - lined eclipsing binary with a relatively long period of 15.33 days @xcite and nearly identical components . the first photoelectric light curve was obtained and analyzed by @xcite , but the masses could not be determined dynamically because no spectroscopic observations were available at the time .
this was remedied by @xcite , who reported radial - velocity measurements for both components and analyzed them in conjunction with the @xmath12-band light curve from @xcite to obtain the absolute masses ( @xmath132.2 @xmath14 ) and radii ( @xmath131.8 @xmath15 ) with relative errors of about 4% and 2% , respectively .
the system is noteworthy in that it presents a periastron advance that is dominated by the general relativistic effect , estimated to be several times larger than the classical effects due to tidal and rotational distortions ..
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however , there has been some disagreement over the precise rate of apsidal motion , which is fairly slow and difficult to determine , and how closely it conforms to theoretical expectations .
some authors have obtained good agreement with the predicted motion , while others have measured a rate of precession that is too slow , and argued that may belong to a small group of binaries including di her and as cam that display similar discrepancies .
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Suppose that you have an abstract for a scientific paper: we define algebraic structures on graph cohomology and prove that they correspond to algebraic structures on the cohomology of the spaces of imbeddings of @xmath0 or @xmath1 into @xmath2 . as a corollary , we deduce the existence of an infinite number of nontrivial cohomology classes in @xmath3 when @xmath4 is even and greater than 3 .
finally , we give a new interpretation of the anomaly term for the vassiliev invariants in @xmath5 . .
And you have already written the first three sentences of the full article: in this paper we consider the spaces @xmath3 of imbeddings of the circle into @xmath2 and the spaces @xmath6 of imbeddings of the real line into @xmath2 with fixed behavior at infinity , namely , imbeddings that coincide with a fixed imbedded line in @xmath2 outside a compact subset .
when @xmath7 one can define , using configuration space integrals , chain maps from certain graph complexes @xmath8 or @xmath9 to the de rham complexes of the spaces of imbeddings : @xmath10 we will use the same symbol @xmath11 also for the induced maps in cohomology .
our main interest is to determine which algebraic structures are preserved by the maps @xmath11 . on the one side , in fact ,.
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the de rham complexes are differential graded commutative algebras .
moreover , there exist a multiplication @xmath12 given by attaching the end of the first imbedding to the beginning of the second , and rescaling .
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Suppose that you have an abstract for a scientific paper: weak measurement is an important technique for detecting the tiny spin - dependent splitting in photonic spin hall effect .
the weak measurement is only valid when the probe wavefunction remains almost undisturbed during the procedure of measurements .
however , it does not always satisfy such condition in some practical situations , such as in the strong - coupling regime or the preselected and postselected states are nearly orthogonal . in this paper , we develop a modified weak measurement for detecting photonic spin hall effect when the probe wavefunction is distorted .
we find that the measuring procedure with preselected and postselected ensembles is still effective .
this scheme is important for us to detect the photonic spin hall effect in the case where neither weak nor strong measurements can detect the spin - dependent splitting .
the modified theory is valid not only in weak - coupling regime but also in the strong - coupling regime , and especially in the intermediate regime .
the theoretical models of conventional weak measurements and modified weak measurements are established and compared .
we show that the experimental results coincide well with the predictions of the modified theory . .
And you have already written the first three sentences of the full article: weak measurements as an extension of quantum measurements were first introduced by aharonov , albert , and vaidman @xcite . in quantum measurements , the observable of system couples a probe state with a pointer whose value can be read out by a meter . in general ,
the conventional quantum measurements involve in a process of strong coupling with the probe wavefunction is distorted .
weak measurements suggest that the coupling between the observable and the probe state is weak and the probe wavefunction remains almost undisturbed ..
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the weak value of an observable @xmath0 outside the eigenvalue spectrum can be obtained and the results are much larger than any eigenvalues of the quantum system . it is shown that the weak value @xmath1 can be formed as a simple expression @xmath2 in which @xmath3 and @xmath4 are the preselected and postselected states , respectively @xcite . indeed , the weak measurements have become a useful tool for high - precision measurements of small physical parameters , such as single - photon tunneling time @xcite , deflections of light beam @xcite , phase shift @xcite , frequency shift @xcite , single - photon nonlinearity @xcite , high - resolution phase estimation @xcite , and angular rotations @xcite .
in addition , it also assists us in researching fundamental questions of quantum mechanics such as single photon s polarization@xcite , hardy s paradox @xcite , photon trajectories @xcite , heisenberg s uncertainty principle @xcite , quantum polarization state @xcite , direct measurement of the quantum wavefunction @xcite , high - dimensional state vector @xcite , and quantum cheshire cat @xcite . as one of important applications , hosten and kwiat develop a weak measurement to detect a tiny spin - dependent splitting in photonic spin hall effect ( she ) @xcite .
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Suppose that you have an abstract for a scientific paper: frequently it is argued that the microstates responsible for the bekenstein hawking entropy should arise from some physical degrees of freedom located near or on the black hole horizon . in this essay
we elucidate that instead entropy may emerge from the conversion of physical degrees of freedom , attached to a generic boundary , into unobservable gauge degrees of freedom attached to the horizon . by constructing the reduced phase space
it can be demonstrated that such a transmutation indeed takes place for a large class of black holes , including schwarzschild . .
And you have already written the first three sentences of the full article: of all the problems quantum gravity is beset with , the most serious is the absence of experimental data even if we had the correct theory how would we know ?
would its beauty alone reveal its truth ? depending on philosophical prejudices sometimes this is answered affirmatively , but more cautious people invoke nature as the ultimate arbitrator . what can be done to satisfy or at least appease the latter in the absence of experiments ?
fortunately , there are some aspects of classical and semi - classical gravity that serve as selection criteria . for instance , a hypothetical theory of quantum gravity failing to reproduce einstein s equations , at least in some limit , would be considered as perverse ..
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let us now search for some semi - classical selection criterion , because reproducing the einstein equations certainly is laudable but hardly a milestone .
according to @xcite the `` closest thing to experimental data '' we have at our disposal is the bekenstein hawking law , @xmath0 which states that the black hole ( bh ) entropy @xmath1 equals to a quarter of the horizon surface area @xmath2 .
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Suppose that you have an abstract for a scientific paper: considering some deposition models with limited mobility , we show that the typical decay of the interface width to its saturation value is exponential , which defines the crossover or saturation time @xmath0 .
we present a method to calculate a characteristic time @xmath1 proportional to @xmath0 and estimate the dynamical exponent @xmath2 . in one dimensional substrates of lengths @xmath3 , the method is applied to the family model , the restricted solid - on - solid ( @xmath4 ) model and the ballistic deposition .
effective exponents @xmath5 converge to asymptotic values consistent with the corresponding continuum theories .
for the two - dimensional family model , the expected dynamic scaling hypothesis suggests a particular definition of @xmath1 that leads to @xmath6 , improving previous calculations based on data collapse methods .
for the two - dimensional @xmath4 model , we obtain @xmath7 and @xmath8 , in agreement with recent large scale simulations . .
And you have already written the first three sentences of the full article: statistical deposition models have attracted much attention in the last years because they may describe real systems features by representing the basic growth mechanisms as simple stochastic processes , thus neglecting the details of the microscopic interactions @xcite .
some examples are the family model @xcite , the restricted solid - on - solid ( @xmath4 ) model of kim and kosterlitz @xcite and the ballistic deposition ( @xmath9 ) model @xcite .
the former one is representative of the edwards - wilkinson ( @xmath10 ) universality class @xcite of linear growth , while the other ones are representative of the kardar - parisi - zhang ( @xmath11 ) class @xcite of non - linear growth ..
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more complex models involve the competition among deposition , diffusion and aggregation @xcite and may represent quantitatively real systems features .
often one is interested in surface properties , then the main quantity to be measured is the interface width of the deposit . if deposition occurs in a @xmath12-dimensional substrate of length @xmath13 , then the interface width at time @xmath14 is defined as @xmath15 } ^{1/2 } } \right > } \label{eq:1}\ ] ] or as @xmath16 } ^{1/2 } .
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Suppose that you have an abstract for a scientific paper: the he@xmath0i @xmath15876 absorption line recently discovered in the spectrum of the companion to the millisecond pulsar psr j1740 - 5340 is tentatively attributed to electron impact excitations due to the irradiation of its atmosphere by @xmath2-rays emitted by the pulsar s magnetosphere .
numerical calculations , similar to those carried out previously for type ib sne , indicate that a pulsar beam with photon energies @xmath3 1 mev gives rise to a @xmath15876 line of the observed strength if the beam s spin - down conversion efficiency approaches 1% . however , a significant difficulty for the proposed mechanism is the strength of the singlet line at @xmath16678 .
compared to the corresponding triplets , singlet lines are weak because of the loss of excitation when photons emitted in the series @xmath4 ionize hydrogen atoms , an effect absent in the hydrogen - free atmospheres of type ib sne . .
And you have already written the first three sentences of the full article: the binary millisecond pulsar psr j1740 - 5340 was recently discovered in the globular cluster ngc 6397 by damico et al .
( 2001a ) with the parkes radio telescope . they reported a spin period of @xmath5ms , a @xmath6 day circular orbit , and eclipses at @xmath7 ghz that last for more than 40% of the orbital period .
subsequent parkes observations ( damico et al ..
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2001b ) allowed an accurate timing solution yielding the spin - down rate as well as the binary s coordinates . with the position known , ferraro et al .
( 2001 ) used archived images to obtain a secure optical identification with a star ( wf4 - 1 ) previously listed as a by dra candidate ( taylor et al .
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Suppose that you have an abstract for a scientific paper: i show stable , localized , single and multi - spot patterns of three classes stationary , moving , and rotating that exist within a limited range of parameter values in the two - dimensional gray - scott reaction - diffusion model with @xmath0 .
these patterns exist in domains of any size , and appear to derive their stability from a constructive reinforcement effect of the standing waves that surround any feature .
there are several common elements including a spot that behaves as a quasiparticle , a u - shaped stripe , and a ring or annulus , or a portion thereof which combine to form a great variety of stable structures .
these patterns interact with each other in a variety of ways .
there are similarities to other reaction - diffusion systems and to physical experiments ; i offer several suggestions for further research .
key words : gray - scott model , reaction - diffusion , pattern formation , numerical simulation pacs : 82.40.ck , 82.40.bj , 47.54.de , 87.18.hf ' '' '' / / / * * / * * / * * .
And you have already written the first three sentences of the full article: the gray - scott model @xcite is a widely - studied model of a pair of reactions involving cubic autocatalysis .
it has been applied in reaction - diffusion models in one @xcite , two @xcite and three @xcite dimensions .
widely - known results include the existence of stable single spots , self - replication of spots , spontaneous formation of stripes and hexagonal arrays of spots , and turing patterns @xcite ..
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findings that show a lack of moving stable patterns , e.g. @xcite apply only in 1-d or a limited region of the 2-d system parameter space ( @xcite p. 81 and
@xcite p. 3 ) .
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Suppose that you have an abstract for a scientific paper: mass - market mobile security threats have increased recently due to the growth of mobile technologies and the popularity of mobile devices .
accordingly , techniques have been introduced for identifying , classifying , and defending against mobile threats utilizing static , dynamic , on - device , off - device , and hybrid approaches . in this paper , we contribute to the mobile security defense posture by introducing andro - profiler , a hybrid behavior based analysis and classification system for mobile malware .
andro - profiler classifies malware by exploiting the behavior profiling extracted from the integrated system logs including system calls , which are implicitly equivalent to distinct behavior characteristics .
andro - profiler executes a malicious application on an emulator in order to generate the integrated system logs , and creates human - readable behavior profiles by analyzing the integrated system logs . by comparing the behavior profile of malicious application with representative behavior profile for each malware family ,
andro - profiler detects and classifies it into malware families .
the experiment results demonstrate that andro - profiler is scalable , performs well in detecting and classifying malware with accuracy greater than @xmath0 , outperforms the existing state - of - the - art work , and is capable of identifying zero - day mobile malware samples
. * keywords . * behavior profiling , similarity , system call , android , malware .
And you have already written the first three sentences of the full article: the explosive growth in the number of mobile devices running the android platform has attracted the attention of hackers for the wealth of sensitive information that are usually stored on mobile devices , including phone numbers , short messages , confidential emails and correspondences , and banking information and credentials .
the availability of this information in many mass - market mobile devices makes them a desirable target for hackers , who excelled at developing a large number of mobile malicious software ( malware ) , making the security of mobile devices one of the most important and challenging areas of research .
for example , according to a report by mcafee , the total number of mobile malware continued its linear climb as it broke 8 million in the second quarter of 2015 , and increased by 17% over the first quarter of the same year @xcite ..
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moreover , new malware families and variants were reported to appear approximately 1 million times in the same quarter . to address this trend , antivirus ( av )
vendors analyze a large number of malware samples daily in order to prevent them from spreading widely and to guide users on disinfection and risk management by classifying malware into broad families .
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Suppose that you have an abstract for a scientific paper: the magnetic field structure in gamma - ray burst ( grb ) outflows is of great interest as it can provide valuable clues that might help pin down the mechanism responsible for the acceleration and collimation of grb jets .
the most promising way of probing this magnetic field structure is through polarization measurements of the synchrotron emission from the grb ejecta , which includes the prompt @xmath0-ray emission and the emission from the reverse shock .
measuring polarization in @xmath0-rays with current instruments is extremely difficult : so far there is only one claim of detection ( a very high degree of linear polarization in grb 021206 ) which despite the favorable conditions remains highly controversial .
the emission from the reverse shock that propagates into the ejecta as it is decelerated by the ambient medium peaks in the optical on a time scale of tens of seconds ( the so called ` optical flash ' ) and dominates the optical emission up to about ten minutes after the grb .
unfortunately , no polarization measurements of this optical emission have been made to date . however , after the reverse shock finishes crossing the shell of grb ejecta , the shocked ejecta cools adiabatically and radiates at lower and lower frequencies .
this emission peaks in the radio after about one day , and is called the ` radio flare ' .
we use vla data of radio flares from grbs to constrain the polarization of this emission .
we find only upper limits for both linear and circular polarization .
our best limits are for grb 991216 , for which we find @xmath1 upper limits on the linear and circular polarization of @xmath2 and @xmath3 , respectively .
these limits provide interesting constraints on existing grb models .
specifically , our results are hard to reconcile with a predominantly ordered toroidal magnetic field in the grb outflow together with a ` structured ' jet , where the energy per solid angle drops as the inverse square of the angle from the jet axis , that is expected in models....
And you have already written the first three sentences of the full article: the detection of linear polarization at the level of @xmath4 in the optical afterglow emission of several gamma - ray bursts ( grbs ; see * ? ? ?
* for a review ) has been widely considered as a confirmation that synchrotron emission is the dominant radiation mechanism , at least in the afterglow stage .
synchrotron radiation is also believed to be the dominant emission mechanism in the prompt @xmath0-ray emission and in the emission from the reverse shock , although the observational support for this is not as strong as for the afterglow ..
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soon after the first detection of linear polarization in the afterglow emission @xcite it has been realized that the temporal evolution of the polarization ( both the degree of polarization @xmath5 and its position angle @xmath6 ) can probe the magnetic field structure in the emitting region , as well as the structure and the dynamics of grb jets @xcite .
while the polarization properties of the afterglow emission have received relatively wide attention @xcite , the polarization of the prompt grb emission received very little attention , in the emission from the grb ejecta , which includes the prompt @xmath0-ray emission , and the emission from the reverse shock ( the ` optical flash ' and ` radio flare ' ) . ] before the detection of a very high degree of linear polarization ( @xmath7 ) in the prompt @xmath0-ray emission of grb 021206 @xcite .
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Suppose that you have an abstract for a scientific paper: we report a systematic study on the directional sensitivity of a direct dark matter detector that detects the polar angle of a recoiling nucleus . a weakly interacting massive particle ( wimp)-mass independent method is used to obtain the sensitivity of a general detector in an isothermal galactic dark matter halo . by using two - dimensional distributions of energy and polar angle ,
a detector without head - tail information with 6.3 times the statistics is found to achieve the same performance level as a full three - dimensional tracking dark matter detector .
optimum operation orientations are obtained for various experimental configurations , with detectors that are space- or earth - fixed , have head - tail capability or not , and use energy information or not .
earth - fixed detectors are found to have best sensitivity when the polar axis is oriented at a 45 degree angle from the earth s pole . with background contamination that mimics the wimp signal s energy distribution ,
the performance is found to decrease at a rate less than the decrease of signal purity .
the wimp - mass dependence of the performance of a detector with various energy thresholds that uses gaseous xenon as target material is reported .
we find that with a @xmath0 spin - independent wimp - nucleon cross - section and a 30 gev wimp , a @xmath1 kg@xmath2year s exposure with a polar detector of 10 kev threshold can make a three sigma discovery of directional wimps in the isothermal galactic dark matter halo . for a columnar recombination detector ,
experimental considerations are discussed . .
And you have already written the first three sentences of the full article: many experiments have attempted to directly detect weakly interacting massive particle ( wimp ) dark matter candidates via their elastic scattering on target nuclei @xcite .
the lux experiment has recently limited the spin - independent cross sections to be under @xmath3 for 33 gev wimp mass @xcite .
a method that has commonly been used is to measure signals associated with the deposited energy of the nuclear recoil ..
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however , background processes , such as those induced by neutrons , can mimic wimp signals @xcite . to overcome this problem , a
`` smoking gun '' wimp signal would be its unique directional event - rate dependence @xcite . when viewed from the earth ,
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Suppose that you have an abstract for a scientific paper: a 1d metallic surface state was created on an anisotropic insb(001 ) surface covered with bi .
angle - resolved photoelectron spectroscopy ( arpes ) showed a 1d fermi contour with almost no 2d distortion .
close to the fermi level ( @xmath0 ) , the angle - integrated photoelectron spectra showed power - law scaling with the binding energy and temperature .
the arpes plot above @xmath0 obtained thanks to thermally broadened fermi edge at room temperature showed a 1d state with continuous metallic dispersion across @xmath0 and power - law intensity suppression around @xmath0 .
these results strongly suggest a tomonaga - luttinger liquid on the bi / insb(001 ) surface . the fermi liquid theory of ordinal three - dimensional ( 3d ) metals breaks down in one - dimensional ( 1d ) systems to produce various exotic quantum phases .
tomonaga - luttinger liquid ( tll ) @xcite is an exactly solvable model of a gapless 1d quantum system , that is characterized by power - law scaling and spin - charge separation for low - energy excitation spectra @xcite .
so far , various 1d systems have been studied as tll candidates . only a few have shown metallic states with power - law spectral features , e.g. , carbon nanotubes @xcite and lithium purple bronze @xcite .
the other characteristic of spin - charge separation has been reported in some 3d materials with 1d electronic structures @xcite .
the surface of semiconductors is known to show various self - assembled 1d atomic structures that are regarded as suitable systems for studying 1d metallic states @xcite , such as in / si(111 ) @xcite , au / si(557 ) @xcite , and pt / ge(001 ) @xcite . on such surface systems
, @xmath1-@xmath2 electron / hole doping can be performed by the deposition of additional atoms , and the local atomic structure can be observed / controlled by scanning probe techniques .
these manipulations on the surface 1d states can provide further insight into 1d physics .
hence , surface tlls have attracted much attention in the....
And you have already written the first three sentences of the full article: insb(001 ) substrates ( @xmath10-type , carrier concentration of 2@xmath610@xmath11 @xmath12 ) were cleaned by repeated cycles of sputtering and annealing up to 680 k until the @xmath15(8@xmath62 ) low - energy electron diffraction ( leed ) pattern was observed .
then , a nominal 3 monolayers ( ml ) of bi were evaporated at room temperature : 1 ml is defined as the atom density of bulk - truncated insb(001 ) and the coverage was estimated by using a quartz microbalance . a subsequent flash by direct current heating up to 680 k for @xmath1310 seconds produced the @xmath14(1@xmath63 ) surface , as indicated by the sharp and low - background leed pattern shown in fig .
1 ( a ) of the main text . as shown in fig ..
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s1 ( a ) , the excess bi was removed after the flash . from the height of bi 5@xmath42 with linear - background subtraction ,
the coverage of bi on the ( 1@xmath63 ) surface was @xmath131.5 ml . sometimes , we could find faint fractional spots showing the @xmath15(2@xmath66 ) periodicity on the flashed surface , which suggested a small fraction of the coexisting area with the @xmath15(2@xmath66 ) periodicity , as shown in fig .
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Suppose that you have an abstract for a scientific paper: we have investigated whether or not a tidal stripping scenario can reproduce the observed surface - brightness profile of @xmath0 centauri using @xmath1-body simulations .
assuming that the progenitor of @xmath0 centauri is a dwarf elliptical galaxy , we model it with a king model with a core radius being the same as that of @xmath0 centauri .
a dark matter halo of the dwarf is not taken into account .
we consider two different models of the milky way potential : a singular isothermal sphere and a three - component model .
the progenitor dwarf is expressed as an @xmath1-body system , which orbits in the fixed galactic potential .
the dwarf lost more than 90 per cent of its mass during the first few pericenter passages .
thereafter , the mass remains practically constant .
the final surface - density profile is in good agreement with the observational data on @xmath0 centauri , if the pericenter distance of the orbit of the progenitor dwarf is around @xmath2 .
this value is within the error bar of the current proper motion data on @xmath0 centauri and galactic parameters .
although our simulation is limited to a king - like progenitor dwarf without a dark matter halo , it strongly suggests that the current density profile of @xmath0 centauri is nicely reproduced by a tidal stripping scenario , in other words , that @xmath0 centauri can plausibly be identified with a stripped dwarf elliptical . .
And you have already written the first three sentences of the full article: @xmath0 centauri ( ngc 5139 ) is , to the best of our knowledge , the most massive globular cluster in the milky way , with a mass around @xmath3 @xcite .
furthermore , it shows peculiar chemical and dynamical features , such as the wide spread in metallicity distribution of member stars @xcite and the difference in kinematics of metal - rich and metal - poor populations @xcite .
some member stars show an enhancement of s - process elements produced by agb stars ( e.g. , * ? ? ?.
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* ) , which means that the potential well must have been deep enough to trap the gas ejected from agb stars @xcite .
a merger model @xcite can explain the kinematics and metallicity spread , but has difficulty in accounting for the presence of s - process elements .
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Suppose that you have an abstract for a scientific paper: a general diffuse interface model with a realistic equation of state ( e.g. peng - robinson equation of state ) is proposed to describe the multi - component two - phase fluid flow based on the principles of the nvt - based framework which is a latest alternative over the npt - based framework to model the realistic fluids .
the proposed model uses the helmholtz free energy rather than gibbs free energy in the npt - based framework .
different from the classical routines , we combine the first law of thermodynamics and related thermodynamical relations to derive the entropy balance equation , and then we derive a transport equation of the helmholtz free energy density .
furthermore , by using the second law of thermodynamics , we derive a set of unified equations for both interfaces and bulk phases that can describe the partial miscibility of two fluids . a relation between the pressure gradient and chemical potential gradients
is established , and this relation leads to a new formulation of the momentum balance equation , which demonstrates that chemical potential gradients become the primary driving force of fluid motion .
moreover , we prove that the proposed model satisfies the total ( free ) energy dissipation with time . for numerical simulation of the proposed model
, the key difficulties result from the strong nonlinearity of helmholtz free energy density and tight coupling relations between molar densities and velocity . to resolve these problems
, we propose a novel convex - concave splitting of helmholtz free energy density and deal well with the coupling relations between molar densities and velocity through very careful physical observations with a mathematical rigor .
we prove that the proposed numerical scheme can preserve the discrete ( free ) energy dissipation .
numerical tests are carried out to verify the effectiveness of the proposed method .
multi - component two - phase flow ; diffuse interface model ; partial miscibility ; energy dissipation ; realistic equation....
And you have already written the first three sentences of the full article: modeling and simulation of multiphase fluid systems with a realistic equation of state ( e.g. peng - robinson equation of state @xcite ) has become an attractive and challenging research topic in the chemical and reservoir engineering @xcite .
it plays very important role in the pore scale modeling and simulation of subsurface fluid flow , especially shale gas reservoir that has become an increasingly important source of natural gas in the recent years .
the mathematical models of multiphase fluids are often formulated by a set of thermodynamic state variables and fluid velocity . in the traditional framework of modeling multiphase fluids ,.
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the thermodynamic state variables are the pressure , temperature , and chemical composition ( the so - called npt - based framework ) .
this framework has been extensively used in many applications @xcite . however , the npt - based framework has some essential limitations @xcite .
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Suppose that you have an abstract for a scientific paper: we explicitly calculate the fundamental group of the space @xmath0 of all immersed closed curves on a surface @xmath1 .
it is shown that @xmath2 , @xmath3 , for @xmath4 .
it is also proved that @xmath5 , and @xmath6 , @xmath7 , for @xmath1 equal to @xmath8 or @xmath9 .
_ this paper will appear in math .
scand . , _ _ probably in vol * 86 * ( no
. 1 ) ( 2000 ) , to be issued in april 2000 _ by a surface we mean any smooth two - dimensional manifold . .
And you have already written the first three sentences of the full article: recently the space of closed curves on a surface attracted a lot of attention .
the interest was initiated by the work of v. arnold @xcite , who axiomatically defined invariants @xmath10 and @xmath11 of generic curves on @xmath12 . in order to define axiomatically this kind of invariants on an arbitrary surface
@xmath1 one has to know the fundamental group of the space @xmath13 of all immersed closed curves on @xmath1 ..
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however , as far as i know , this group is not calculated in the literature . in this paper
we explicitly calculate it .
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Suppose that you have an abstract for a scientific paper: we introduce and study graphic lambda calculus , a visual language which can be used for representing untyped lambda calculus , but it can also be used for computations in emergent algebras or for representing reidemeister moves of locally planar tangle diagrams .
[ section ] [ theorem]proposition [ theorem]lemma [ theorem]corollary [ theorem]definition [ theorem]remark [ section ] .
And you have already written the first three sentences of the full article: graphic lambda calculus consists of a class of graphs endowed with moves between them .
it might be considered a visual language in the sense of erwig @xcite .
the name `` graphic lambda calculus '' comes from the fact that it can be used for representing terms and reductions from untyped lambda calculus ..
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it s main move is called `` graphic beta move '' for it s relation to the beta reduction in lambda calculus .
however , the graphic beta move can be applied outside the `` sector '' of untyped lambda calculus , and the graphic lambda calculus can be used for other purposes than the one of visual representing lambda calculus . for other visual , diagrammatic representation of lambda calculus see the vex language @xcite , or david keenan s @xcite .
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Suppose that you have an abstract for a scientific paper: we search for vortices in a generalized abelian chern - simons model with a non - standard kinetic term .
we illustrate our results plotting and comparing several features of the vortex solution of the generalized model with those of the vortex solution found in the standard chern - simons model . .
And you have already written the first three sentences of the full article: the study of vortices in planar chern - simons ( cs ) models has been pioneered in refs . @xcite . since then , a lot of investigations on chern - simons vortices have been done ; see , e.g. , dunne1,dunne2,sakai , schap . during the past years , however , theories with non - canonical kinetic term , named generalized of @xmath0-field models , have been intensively studied .
generically , their applications have been found in strong interaction physics , with the skyrme @xcite and skyrme - like models @xcite , and also in cosmology with the so - called @xmath0-essence models @xcite .
@xmath0 fields change the way the fields approach their vacuum values , allowing thereby , for instance , the existence of solitons which approach their vacuum values in a power - like instead of an exponential fashion and which therefore have a compact support @xcite ..
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also , @xmath0-theories allow to avoid derrick s theorem @xcite increasing the chances to find soliton solutions in symmetry - breaking models . by this way
, several @xmath0-topological defects were already studied by several authors babichev1,jin , sarangi , bmp , bglm , bazeia0,bazeia3,babichev2,babichev3 and the overall conclusion is that their properties can be quite different from the standard ones depending specifically of the choice made for the kinetic term .
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Suppose that you have an abstract for a scientific paper: we report heating - compensated interlayer tunneling spectroscopy ( its ) performed on stacks of overdoped bi@xmath0sr@xmath0cacu@xmath0o@xmath1 intrinsic junctions , where most of bias - induced heating in the its was eliminated .
the onset temperature of the pseudogap ( pg ) , revealed in the hump structure of the electronic excitation spectra , reached nearly room temperature for our overdoped intrinsic junctions , which represented the genuine pg onset . at a temperature below but close to @xmath2 , both the superconducting coherence peak and the pseudogap hump coexisted , implying that the two gaps are of separate origins .
the hump voltage increased below @xmath2 , following the superconducting gap voltage , which led to a conclusion that the hump structure below @xmath2 in our its arose from the combined contribution of the quasiparticle spectral weights of two different characters ; one of the superconducting state and another of the pg state near the antinodal region . .
And you have already written the first three sentences of the full article: conventional superconductors in their superconducting state are characterized by opening of the superconducting gap ( sg ) in the electronic density of states ( dos ) .
superconductivity appears when electrons bind into cooper pairs and condense with long - range order below the superconducting transition temperature @xmath2 .
cuprate superconductors , however , as one of the most intriguing characteristics in their normal state , show the unusual emergence of the pseudogap ( pg ) in the electronic excitation spectrum even above @xmath2 , which persists up to a temperature @xmath3 , the pg onset temperature ..
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it has been widely accepted that understanding the pg origin and the relation between the pg and the sg may lead to a key to finding the basic mechanism of high - temperature superconductivity,@xcite which is not fully resolved up to the present .
there are two schools of thought as to understanding the pg in the cuprate physics : one - gap and two - gap ones .
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Suppose that you have an abstract for a scientific paper: the paper considers a distributed robust estimation problem over a network with directed topology involving continuous time observers .
while measurements are available to the observers continuously , the nodes interact according to a round - robin rule , at discrete time instances .
the results of the paper are sufficient conditions which guarantee a suboptimal @xmath0 level of consensus between observers with sampled interconnections . large - scale systems , distributed estimation , robust observers , consensus , vector dissipativity , sampled - input systems , time - delay systems . .
And you have already written the first three sentences of the full article: the problem of distributed estimation is one of very active topics in the modern control theory and signal processing literature .
interest in this problem is motivated by a growing number of applications where a decision about the observed process must be made simultaneously by spatially distributed sensors , each taking partial measurements of the process .
when the process and measurements are subject to noise and disturbance , robustness aspects of the problem come into prominence . in the past several years.
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, a number of results have been presented in the literature which develop the @xmath0 control and estimation theory for distributed systems subject to uncertain perturbations ; e.g. , see @xcite . in particular , methodologies of distributed sampled - data @xmath0 filtering have been considered , e.g. , in @xcite .
that reference emphasized several distinctive aspects of realistic sensor networks , among them coupling between sensor nodes through the information communicated between neighbouring sensor nodes and the sampled nature of that coupling , which is dictated by the digital communication technology .
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Suppose that you have an abstract for a scientific paper: the derivation of the expressions of momentum and energy of a particle in special relativity is often less than satisfactory in elementary texts . in some ,
it is obtained by resorting to quantum or electrodynamic considerations , in others by introducing less - than - elementary concepts , like that of a four - vector , or even misleading ones , like `` relativistic mass '' .
nevertheless it is possible , following ideas described by einstein in 1935 , to obtain a fully elementary derivation of these expressions based only on the lorentz transformations , on the conservation laws , and on the newtonian limit .
the resulting argument allows for a clearer and logically consistent introduction to the basic concepts of relativistic dynamics . .
And you have already written the first three sentences of the full article: several texts provide an elementary derivation of the kinematics of special relativity , eventually based on the first part of einstein s fundamental paper of 1905 .
@xcite starting from the two postulates of the total equivalence of inertial reference systems , and of the constancy of the speed of light in all such systems , it is in fact easy to obtain the expression of the lorentz transformation of space - time coordinates .
a particularly simple and appealing derivation is obtained by exploiting bondi s so - called @xmath0-calculus , @xcite itself based on the doppler effect ..
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nevertheless going from kinematics ( the lorentz transformation ) to dynamics , and in particular to the relativistic expressions of momentum and energy , is often achieved by resorting to more sophisticated concepts , like that of a four - vector , or by the use of quantum considerations .
( one example of this approach is the `` elementary derivation '' suggested by f. rohrlich , @xcite which exploits the expressions of the momentum and energy of a photon of frequency @xmath1 . )
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Suppose that you have an abstract for a scientific paper: using a modified lennard - jones model for elliptic particles and spherical impurities , we present results of molecular dynamics simulation in two dimensions . in one - component systems of elliptic particles , we find an orientation phase transition on a hexagonal lattice as the temperature @xmath0 is lowered .
it is also a structural one because of spontaneous strain . at low @xmath0 ,
there arise three martensitic variants due to the underlying lattice , leading to a shape memory effect without dislocation formation .
thermal hysteresis , a minimum of the shear modulus , and a maximum of the specific heat are also found with varying @xmath0 . with increasing the composition @xmath1 of impurities ,
the three kinds of orientation domains are finely divided , yielding orientation - strain glass with mesoscopically ordered regions still surviving .
if the impurities are large and repulsive , planar anchoring of the elliptic particles occurs around the impurity surfaces . if they are small and attractive , homeotropic anchoring occurs .
clustering of impurities is conspicuous . with increasing the anchoring power and/or the composition of the impurities
, positional disorder can also be enhanced .
we also investigate the rotational dynamics of the molecular orientations . .
And you have already written the first three sentences of the full article: certain anisotropic molecules such as n@xmath2 , c@xmath3 , and kcn form a cubic crystal and , at lower temperatures , they undergo an orientation phase transition with a specific - heat peak @xcite , where the crystal structure changes to a noncubic one . furthermore , mixtures of anisotropic particles @xcite such as ( kcn)@xmath4(kbr)@xmath5 and one - component systems of globular molecules @xcite such as ethanol and cyclohexanol become orientation glass . in such glass , the phase ordering should occur only on small spatial scales with mesoscopically heterogeneous orientation fluctuations .
because of anisotropic molecular shapes , there should be a direct ( proper ) coupling between the molecular orientations and the lattice deformations @xcite .
in fact , the shear modulus becomes small around the orientational order - disorder or glass transition @xcite ..
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these systems thus exhibit singular acoustic and plastic behaviors @xcite , but there has been no systematic experiment in the nonlinear response regime .
many of these anisotropic molecules have dipolar moments also , yielding dielectric anomaly near the transition . in metallic alloys
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Suppose that you have an abstract for a scientific paper: we have determined detailed radio spectra for 26 compact sources in the starburst nucleus of m82 , between @xmath0 74 and 1.3 cm .
seventeen show low - frequency turnovers .
one other has a thermal emission spectrum , and we identify it as an region .
the low frequency turnovers are due to absorption by interstellar thermal gas in m82 .
new information on the agn candidate , 44.01 + 595 , shows it to have a non - thermal falling powerlaw spectrum at the highest frequencies , and that it is strongly absorbed below 2 ghz .
we derive large magnetic fields in the supernova remnants , of order 1 - 2 @xmath1 milligauss , hence large pressures in the sources suggest that the brightest ones are either expanding or are strongly confined by a dense interstellar medium . from the largest source in our sample ,
we derive a supernova rate of 0.016 yr@xmath2 . .
And you have already written the first three sentences of the full article: supernovae ( sne ) and supernova remnants ( snr s ) are thought to be the main `` drivers '' of the starburst phenomenon ( @xcite ) .
detailed radio observations for supernovae and supernova remnants are few , due to the fact that only a small subset of the extragalactic sne discovered each year produce detectable radio emission .
those events for which monitoring data is available ( e.g. @xcite ) have revealed considerable information regarding the evolution of the properties of the expanding shock wave and its emission processes . in intense starbursts like m82 , where a significant population of massive stars has had sufficient time to evolve to the sn stage , we have the unique opportunity to study a collection of snr s of similar age and origin , and their interaction with the surrounding environment ..
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the observations are briefly outlined in section 2 .
we discuss the technique used to fit spectral models in section 3 .
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Suppose that you have an abstract for a scientific paper: in these notes we describe the basic formulation of the parametrization scheme for the instantaneous nonlocal chiral quark model in the three flavor case . we choose to discuss the gaussian , lorentzian - type , woods - saxon and sharp cutoff ( njl ) functional forms of the momentum dependence for the formfactor of the separable interaction .
the four parameters : light and strange quark mass , coupling strength ( @xmath0 ) and range of the interaction ( @xmath1 ) have been fixed by the same phenomenological inputs : pion and kaon mass , pion decay constant and light quark mass in vacuum .
the wood - saxon and lorentzian - type formfactor is suitable for an interpolation between sharp cutoff and soft momentum dependence .
results are tabulated for applications in models of hadron structure and quark matter at finite temperatures and chemical potentials where separable models have proven successful . .
And you have already written the first three sentences of the full article: the phase diagram of quantum chromodynamics ( qcd ) is investigated in large - scale lattice gauge theory simulations @xcite and heavy - ion collision experiments at cern - sps and rhic brookhaven @xcite , where the approximately baryon - free region at finite temperatures is accessible and consensus about the critical temperature for the occurence of a strongly correlated quark - gluon plasma phase ( sqgp ) is developing .
the region of low temperatures and high baryon densities , however , which is interesting for the astrophysics of compact stars , is not accessible to lattice qcd studies yet and heavy - ion collision experiments such as the cbm experiment at fair darmstadt are still in preparation @xcite .
the most stringent of the presently available constraints on the eos of superdense hadronic matter from compact stars and heavy - ion collisions have recently been discussed in ref ..
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@xcite and may form the basis for future systematic investigations of the compatibility of dense quark matter models with those phenomenological constraints . therefore , the question arises for appropriate models describing the nonperturbative properties of strongly interacting matter such as dynamical chiral symmetry breaking and hadronic bound state formation in the vacuum and at finite temperatures and densities .
the nambu jona - lasinio ( njl ) model has proven very useful for providing results to this question within a simple , but microscopic formulation , mostly on the mean - field level , see @xcite .
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Suppose that you have an abstract for a scientific paper: the pairing symmetry in the electron mechanism for superconductivity is explored when charge fluctuations coexist with spin fluctuations .
the extended hubbard model is adopted to obtain , with the fluctuation exchange approximation , a phase diagram against the on - site coulomb repulsion @xmath0 and the off - site repulsion @xmath1 for the square lattice with second - neighbor hopping @xmath2 .
we have found that ( i ) for large @xmath3 a triplet superconductivity with a @xmath4 symmetry can appear just below the charge density wave phase .
the pairing is degenerate with @xmath5 , so a chiral @xmath6 that breaks the time reversal symmetry should result , which is a candidate for the gap function on the @xmath7 band of sr@xmath8ruo@xmath9 and is consistent with a recent measurement of the specific heat .
( ii ) by systematically deforming the fermi surface with varied @xmath2 , we have identified the region where the triplet pairing is most favored to be the region where the fermi surface traverses the van hove singularity with the charge susceptibility strongly enhanced . 2 .
And you have already written the first three sentences of the full article: spin - triplet superconductivity , which is arousing much interests in recent years , is fascinating in a number of ways .
theoretically , a most intriguing question is the following : if we consider the electron mechanism of superconductivity in the most frequently adopted hubbard model with an on - site electron - electron repulsion , we can show that triplet superconductivity is very difficult to realize for the simple reason that the pairing interaction mediated by spin fluctuations is only 1/3 in the triplet channel than in the singlet channel@xcite .
so any theory attempting to explain triplet pairing has to overcome this question ..
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experimentally , the discovery of superconductivity by maeno and coworkers in the layered perovskite ruthenium oxide sr@xmath8ruo@xmath9 have kicked off renewed interests . suggestions for a triplet pairing in this material came from nmr knight shift@xcite and polarized neutron scattering@xcite . a broken time reversal symmetry is further observed with @xmath10sr@xcite and small - angle neutron scattering@xcite . as for the pairing symmetry , nmr and nqr relaxation rates have shown an absence of the hebel - slichter peak@xcite , which suggests line node(s ) in the gap function , which was supported by a specific heat measurement@xcite . while the angular dependence of thermal conductivity indicates the presence of horizontal line - nodes@xcite , a recent field - orientation dependence of the specific heat shows that the gap in the active @xmath7 band has minima along [ 100 ] directions with the passive @xmath11 and @xmath12 bands having gap minima along [ 110 ] directions@xcite .
a theoretical work by zhitomirsky and rice@xcite has proposed horizontal line nodes with a good fit to the specific heat measurement@xcite . as for the mechanism that stabilizes triplet pairing , kuwabara and ogata@xcite , and independently sato and kohmoto@xcite , have suggested that triplet @xmath13-wave pairing can be induced by an anisotropy in the spin fluctuation .
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Suppose that you have an abstract for a scientific paper: in the present work we have searched the existence of the late time acceleration of the universe with string fluid as source of matter in anisotropic heckmann - suchking space - time by using 287 high red shift @xmath0 sn ia data of observed absolute magnitude along with their possible error from union 2.1 compilation . it is found that the best fit values for @xmath1 , @xmath2 , @xmath3 and @xmath4 are 0.2820 , 0.7177 , 0.0002 @xmath5 -0.5793 respectively .
several physical aspects and geometrical properties of the model are discussed in detail .
+ + + + + + + + + * key words : * string , sn ia data , heckmann - suchking space - time . .
And you have already written the first three sentences of the full article: sn ia observations ( riess et al . 1998 ; perlmutter et al . 1999 ) confirmed that the observable universe is undergoing an accelerated expansion .
this acceleration is realized due to unknown cosmic fluid - dark energy ( de ) which have positive energy density and negative pressure .
so , it violate the strong energy condition ( sec ) ..
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the authors of ref . [ 3 ] confirmed that the violation of sec gives anti gravitational effect that provides an elegant description of transition of universe from deceleration zone to acceleration zone . in the literature ,
cosmological constant is the simplest candidate to describe the present acceleration of universe ( grn and hervik 2007 ) but it suffers two problems - the fine tunning and cosmic coincidence problems ( carroll et al .
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Suppose that you have an abstract for a scientific paper: the discrepancy between maximally entangled states and maximally non - classical quantum correlations is well - known but still not well understood .
we aim to investigate the relation between quantum correlations and entanglement in a family bell inequalities with @xmath0-settings and @xmath1 outcomes . using analytical as well as numerical techniques , we derive both maximal quantum violations and violations obtained from maximally entangled states .
furthermore , we study the most non - classical quantum states in terms of their entanglement entropy for large values of @xmath1 and many measurement settings .
interestingly , we find that the entanglement entropy behaves very differently depending on whether @xmath2 or @xmath3 : when @xmath2 the entanglement entropy is a monotone function of @xmath1 and the most non - classical state is far from maximally entangled , whereas when @xmath3 the entanglement entropy is a non - monotone function of @xmath1 and converges to that of the maximally entangled state in the limit of large @xmath1 . .
And you have already written the first three sentences of the full article: quantum correlations arising in space - like separated measurement events can be subject to strong correlations that can not be explained by classical physics @xcite . the strength of classical correlations is bounded by bell inequalities , which are known to have quantum violations , certifying the non - classicality of the physics at play . a necessary condition to violate a bell inequality is sharing an entangled quantum state @xcite . for pure states ,
the standard measure of entanglement is the entanglement entropy @xcite , defined as the von neumann entropy of a subsystem of the state .
the relation between entanglement and the strength of quantum correlations has long been considered an interesting question ..
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for the simplest bell scenario , with two parties alice and bob performing one of two two - outcome measurements , the chsh inequality @xcite constitutes a tight bound on the set of classical correlations @xcite . to maximally violate the chsh inequality , one must distribute a state with maximal entanglement entropy ( the so - called maximally entangled state ) .
however , when the chsh inequality was generalized to the cglmp inequality @xcite which considers scenarios with alice and bob choosing one of two @xmath1-outcome measurements , it was discovered that the maximal quantum violation of the cglmp inequality for some low values of @xmath4 can not be achieved by distributing a maximally entangled state between alice and bob @xcite .
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Suppose that you have an abstract for a scientific paper: we investigate the general properties of lattice spin models with emerging fermionic excitations .
we argue that fermions always come in pairs and their creation operator always has a string - like structure with the newly created particles appearing at the endpoints of the string .
the physical implication of this structure is that the fermions always couple to a nontrivial gauge field .
we present exactly soluble examples of this phenomenon in @xmath0 and @xmath1 dimensions .
our analysis is based on an algebraic formula that relates the statistics of a lattice particle to the properties of its hopping operators .
this approach has the advantage that it works in any number of dimensions - unlike the flux - binding picture developed in fqh theory . .
And you have already written the first three sentences of the full article: for many years , it was thought that fermi statistics were fundamental , in the sense that one could only obtain a theory with fermionic excitations by introducing them by hand ( via anti - commuting fields ) .
then , over the past two decades , this view began to change .
a number of real world and theoretical examples showed that fermions and anyons could _ emerge _ as low energy collective modes of purely bosonic systems ..
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the first examples along these lines were the fractional quantum hall states .
@xcite usually we think of the fqh states as examples of anyonic excitations emerging from interacting fermions .
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Suppose that you have an abstract for a scientific paper: we analyse the evolution of a sigmoidal ( s shaped ) active region toward eruption , which includes a coronal mass ejection ( cme ) but leaves part of the filament in place .
the x - ray sigmoid is found to trace out three different magnetic topologies in succession : a highly sheared arcade of coronal loops in its long - lived phase , a bald - patch separatrix surface ( bpss ) in the hours before the cme , and the first flare loops in its major transient intensity enhancement .
the coronal evolution is driven by photospheric changes which involve the convergence and cancellation of flux elements under the sigmoid and filament .
the data yield unambiguous evidence for the existence of a bpss , and hence a flux rope , in the corona prior to the onset of the cme . .
And you have already written the first three sentences of the full article: coronal mass ejections ( cmes ) are large scale eruptions of magnetized plasma from the solar atmosphere into the interplanetary space .
it is generally accepted that their energy source is derived from the free energy contained in sheared or twisted magnetic fields @xcite .
many cme models have been developed and despite the differences in the underlying physics of the eruption , all models at some point involve a magnetic flux rope . from this viewpoint ,.
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the models can be split into those which require the flux rope to exist prior to the eruption , and those in which the flux rope is formed as a result of topological changes in the course of the eruption . in the first category
the rope is fundamental to the cme initiation process .
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Suppose that you have an abstract for a scientific paper: a discretized massless wave equation in two dimensions , on an appropriately chosen square lattice , exactly reproduces the solutions of the corresponding continuous equations .
we show that the reason for this exact solution property is the discrete analog of conformal invariance present in the model , and find more general field theories on a two - dimensional lattice that exactly solve their continuous limit equations .
these theories describe in general non - linearly coupled bosonic and fermionic fields and are similar to the wess - zumino - witten model . .
And you have already written the first three sentences of the full article: since our spacetime may ultimately prove to be discrete , field theories on discrete spacetimes have developed an interest in and of themselves @xcite .
in particular , field theories on two - dimensional discrete spacetimes can be interpreted as string theories with a discrete string worldsheet and a continuous target space .
exact solutions for such theories can often be obtained even after quantization ( see , for example , @xcite ) ..
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yet another approach to discretizing spacetime and constructing a theory of gravity based on stochastic properties of random lattices is advocated by r. sorkin @xcite .
investigation of field theories on discrete spacetime might therefore contribute to our understanding of discrete quantum picture of the universe .
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Suppose that you have an abstract for a scientific paper: we modify the standard abelian - higgs model by introducing spatially - dependent couplings for the scalar and vector fields .
we investigate static , non - cylindrically symmetric solutions of the resulting field equations and propose a pinch solution which interpolates between degenerate vacua along the string , labelled by @xmath0 .
this configuration corresponds to a vortex which shrinks to the planck scale before re - emerging as an anti - vortex , resulting in the formation of a bead pair with one bead either side of the intersection .
the solution is then topologically stable .
a key assumption is that quantities such as phase and winding number , along with those which depend on them like the magnetic flux , become undefined at the planck scale so that regions of opposite winding may be joined via a planck - sized segment of neutral string .
similarities between this solution and the extra - dimensional windings of strings in type iib string theory are discussed and a correspondence between field theory and string theory parameters is suggested . the spatial - dependence of the field couplings is found to have a natural interpretation in the string picture and results from the variation of the winding radius , giving rise to a varying ( effective ) string coupling .
an interesting result is an estimate of the higgs mass ( at critical coupling ) in terms of the parameters which define the klebanov - strassler geometry and which , in principle , may be constrained by cosmological observations . @xmath1 @xmath2 _ @xmath3 center for research in string theory , queen mary , university of london + mile end road , london e1 4ns , uk + _ _ @xmath4 astronomy unit , school of mathematical sciences , queen mary , university of london + mile end road , london e1 4ns , uk + _ _ @xmath5 department of physics and astronomy , university of victoria , victoria , bc + v8p 1a1 , canada _ .
And you have already written the first three sentences of the full article: previous studies of strings in backgrounds with compact extra - dimensions have led to an increased understanding of the formation and evolution of string loops with non - trivial windings in the internal space .
both generic scenarios and compactification schemes specific to type iib string theory have been investigated @xcite-@xcite .
+ in the case of static string loops , it has been shown that the presence of a lifting potential in the compact space traps the windings - giving rise to loops with step - like winding configurations referred to in the literature as cosmic necklaces @xcite-@xcite . from a four - dimensional perspective.
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the windings appear as a series of monopoles or beads " connected by ordinary sections of string .
superficially these resemble the standard string - monopole networks found in field - theoretic models @xcite but their behaviour is , in many ways , fundamentally different . in stark contrast to previous predictions based on field theory defects
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Suppose that you have an abstract for a scientific paper: we present the first results of the analysis of data collected during the 1998 - 99 observational campaign at the 1.3 meter mcgraw - hill telescope , towards the andromeda galaxy ( m31 ) , aimed to the detection of gravitational microlensing effects as a probe of the presence of dark matter in our and in m31 halo .
the analysis is performed using the _ pixel lensing _ technique , which consists in the study of flux variations of unresolved sources and has been proposed and implemented by the agape collaboration .
we carry out a shape analysis by demanding that the detected flux variations be achromatic and compatible with a paczyski light curve .
we apply the durbin - watson hypothesis test to the residuals .
furthermore , we consider the background of variables sources .
finally five candidate microlensing events emerge from our selection . comparing with the predictions of a monte carlo simulation , assuming a standard spherical model for the m31 and galactic haloes , and typical values for the macho mass
, we find that our events are only marginally consistent with the distribution of observable parameters predicted by the simulation . .
And you have already written the first three sentences of the full article: in the last decade much attention has been focused on the possibility that a sizable fraction of galactic dark matter consist of machos ( massive astrophysical compact halo object ) . since 1992 , the macho ( alcock et al . 1993 ) and
eros ( aubourg et al . 1993 ) collaborations have looked towards the large and small magellanic clouds ( lmc and smc ) in order to detect machos using gravitational microlensing .
this technique , originally proposed by paczyski ( 1986 ) , analyses the luminosity variation of resolved source stars , due to the passage of machos close to the line of sight between the source and the observer . the macho collaboration ( alcock et al . 2000 ) discovered 13 - 17 microlensing events towards the lmc ..
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assuming that all events are due to machos in the halo , about @xmath0 of the halo dark matter resides in form of compact objects with a mass in the range @xmath1 @xmath2 .
the eros collaboration ( lasserre et al . 2000 ) observed 6 microlensing events , 5 in the direction of the lmc and 1 in the direction of the smc .
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Suppose that you have an abstract for a scientific paper: recent advances in n - body simulations of dark matter haloes have shown that three - parameter models , in particular the einasto profile characterized by @xmath0 with a shape parameter @xmath1 , are able to produce better fits to the 3d spatial density profiles than two - parameter models like the navarro , frenk and white ( nfw ) , and moore et al . profiles . in this paper , we present for the first time an analytically motivated form for the 2d surface mass density of the einasto family of dark matter haloes , in terms of the 3d spatial density parameters for a wide range of the shape parameter @xmath2 @xmath3 @xmath4 @xmath3 @xmath5 .
our model describes a projected ( 2d ) einasto profile remarkably well between @xmath6 and @xmath7 @xmath8 , with errors less than @xmath9 per cent for @xmath4 @xmath10 and less than @xmath11 per cent for @xmath4 as large as 1 .
this model ( in 2d ) can thus be used to fit strong and weak lensing observations of galaxies and clusters whose total spatial(3d ) density distributions are believed to be einasto - like .
further , given the dependence of our model on the 3d parameters , one can reliably estimate structural parameters of the spatial ( 3d ) density from 2d observations .
we also consider a sersic - like parametrization for the above family of projected einasto profiles and observe that fits with a sersic profile are sensitive to whether one fits the projected density in linear scale or logarithmic scale and yield widely varying results .
structural parameters of einasto - like systems , inferred from fits with a sersic profile , should be used with caution .
[ firstpage ] gravitational lensing galaxies : clusters : general galaxies : fundamental parameters galaxies : haloes galaxies : structure dark matter . .
And you have already written the first three sentences of the full article: gravitational lensing signatures are a response to the projected surface mass column density of matter @xmath12 along the line of sight in galaxies and clusters . upon a suitable deprojection and circular averaging , an estimate of @xmath13 can ,
in principle , be used to trace the spherically averaged 3d density profile @xmath14 . in the past few years
, n - body simulations have shown [ @xcite , @xcite ( nav04 ) , @xcite ( m06 ) , @xcite(s09 ) ] that three - parameter models , especially the einasto @xcite profile and the @xcite de - projected sersic profiles ( ps97 ) , are able to produce better fits to the 3d density profiles of galaxy and cluster - sized dark matter haloes than two - parameter models ( @xcite @xmath15 ( 1996 ) ( nfw ) , @xcite ) ..
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while the ps97 profile has a well known 2d sky projected form - the sersic @xcite profile , there has been no such analytical counterpart for the einasto profile . in this paper
, we present a very good approximation for the 2d projection of the einasto family of 3d profiles .
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Suppose that you have an abstract for a scientific paper: the fractal properties of four - dimensional euclidean simplicial manifold generated by the dynamical triangulation are analyzed on the geodesic distance @xmath0 between two vertices instead of the usual scale between two simplices . in order to make more unambiguous measurement of the fractal dimension
, we employ a different approach from usual , by measuring the box - counting dimension which is computed by counting the number of spheres with the radius d within the manifold .
the numerical result is consistent to the result of the random walk model in the branched polymer region .
we also measure the box - counting dimension of the manifold with additional matter fields .
numerical results suggest that the fractal dimension takes value of slightly more than 4 near the critical point .
furthermore , we analyze the correlation functions as functions of the geodesic distance .
numerically , it is suggested that the fractal structure of four - dimensional simplicial manifold can be properly analyzed in terms of the distance between two vertices .
moreover , we show that the behavior of the correlation length regards the phase structure of 4d simplicial manifold . .
And you have already written the first three sentences of the full article: recently , euclidean simplicial quantum gravity(sqg ) with the additional matter fields has been investigated with using the monte - carlo simulation . from the previous numerical simulation@xcite
, we expect the four - dimensional(4d ) simplicial model realizes the realistic 4d quantum gravity .
especially , in ref ..
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@xcite , it is shown that the relation between sqg and the 4d conformal gravity@xcite , calculating with the grand - canonical method . however , in order to discuss the relation between the discretized model and the continuum theory in detail , we need to analyze the correlations on the 4d simplicial manifold @xmath1 .
namely , we need to discuss the geometry on @xmath1 instead of the statistical properties which have been discussed until now . in order to discuss the geometry on @xmath1
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Suppose that you have an abstract for a scientific paper: a five - level * p@xmath0p * model of the band structure for gaas - type semiconductors is used to describe the spin @xmath1-factor and the cyclotron mass @xmath2 of conduction electrons in gaas / ga@xmath3al@xmath4as quantum wells in an external magnetic field parallel to the growth direction .
it is demonstrated that the previous theory of the @xmath1-factor in heterostructures is inadequate .
our approach is based on an iteration procedure of solving 14 coupled differential * p@xmath0p * equations . the applicability of the iteration procedure is verified . the final eigenenergy problem for the conduction subbands
is reduced to two differential equations for the spin - up and spin - down states of consecutive landau levels .
it is shown that the bulk inversion asymmetry of iii - v compounds is of importance for the spin @xmath1-factor .
our theory with no adjustable parameters gives an excellent description of experimental data on the electron spin @xmath1-factor in gaas / ga@xmath5al@xmath6as rectangular quantum wells for different well widths between 3 and 12 nm .
the same theory describes very well experimental cyclotron masses in gaas / ga@xmath7al@xmath8as quantum wells for the well widths between 6 and 37 nm . .
And you have already written the first three sentences of the full article: spin properties of electrons in semiconductor heterostructures have become in recent years subject of intense experimental and theoretical interest because of their inherent scientific value as well as possible spintronic applications . among numerous heterostructures
, the system gaas / ga@xmath3al@xmath4as has won a unique position .
first , gaas is after silicon the most important semiconductor material ..
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second , the system gaas / ga@xmath3al@xmath4as has well established parameters which allows the theorists to describe new subtle phenomena .
third , due to the advanced growth technology the electrons in gaas quantum wells have very high mobilities making it possible to detect even weak effects .
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Suppose that you have an abstract for a scientific paper: the surface tension of quark matter plays a crucial role for the possibility of quark matter nucleation during the formation of compact stellar objects , because it determines the nucleation rate and the associated critical size .
however , this quantity is not well known and the theoretical estimates fall within a wide range , @xmath0 .
we show here that once the equation of state is available one may use a geometrical approach to obtain a numerical value for the surface tension that is consistent with the model approximations adopted .
we illustrate this method within the two - flavor linear @xmath1 model and the nambu jona - lasinio model with two and three flavors . treating these models in the mean - field approximation
, we find @xmath2 .
such a relatively small surface tension would favor the formation of quark stars and may thus have significant astrophysical implications .
we also investigate how the surface tension decreases towards zero as the temperature is raised from zero to its critical value . .
And you have already written the first three sentences of the full article: lattice - gauge calculations yield a non - vanishing value of the quark condensate @xmath3 in the qcd vacuum @xcite , indicating that chiral symmetry is broken .
this general feature of the vacuum remains present even for massless quarks because the symmetry is then broken spontaneously . on the other hand
, chiral symmetry is expected to become restored at sufficiently high values of the net - baryon density @xmath4 or / and the temperature @xmath5 ..
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the character of this phase change is not yet well understood but it has significant implications in areas such as cosmology and astrophysics and it is a focal point for current experimental and theoretical research in nuclear physics . nuclear collision experiments carried out with the relativistic heavy ion collider ( rhic ) at the brookhaven national laboratory and with the large hadron collider at cern explore systems having relatively small net - baryon densities @xmath4 and the associated chemical potentials @xmath6 are negligible .
lattice calculations can readily be carried out at vanishing @xmath6 and they indicate that a cross - over transformation from the chirally broken phase to the restored phase occurs as the temperature is increased from below to above the cross - over temperature @xmath7 @xcite . the other extreme region of the qcd phase diagram , namely low temperatures and high chemical potentials , can not be addressed by current lattice - qcd methods , due to the fermion sign problem , and studies of this phase region must therefore rely on less fundamental models .
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Suppose that you have an abstract for a scientific paper: the autocorrelation function provides an objective test for the existence of special scales in the hierarchical clustering of young stars .
we apply this measure to single - star photometry for the brightest main sequence stars in the small magellanic cloud ( smc ) , the large magellanic cloud ( lmc ) , m33 , and m31 , using data from the magellanic clouds photometric survey and the massey local group survey .
our primary result is the identification of a transition to a higher correlation dimension ( weaker clustering ) at one kpc in the lmc and m31 , and at 300 pc in m33 .
we suggest that this transition marks the large - scale regime where disk geometry and dynamics set the scale for structure . on smaller scales ,
the correlation functions for each galaxy are scale - free over at least two orders of magnitude , with a projected correlation dimension varying from 1.0 for m31 to 1.8 for the smc .
this variation is probably caused by a combination of differences in stellar ages and masses , physical environment , and extinction . .
And you have already written the first three sentences of the full article: while it is clear that young stars are clustered hierarchically , with ob associations and clusters inside complexes and superassociations , the extent to which there are universal clustering scales is controversial . historically , typical sizes assigned to stellar groupings have depended at least partially on selection criteria and image quality .
efremov ( 1995 ) provides a summary of this history , and concludes that it make sense to consider two distinct scales within the hierarchy : elementary cells on scales of 10 - 100 pc that contain stars with ages up to 10 myr , and large complexes on scales of several hundred parsecs that contain stars with ages up to about 100 myr .
the identification of clusters on different scales is an area of active research , using a variety of surveys and instruments ..
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for example , livanou et al . ( 2007a , 2007b ) combine optical and infrared obserations to find clusters in the magellanic clouds on scales ranging from 150 pc to 1500 pc , that they classify as aggregates , complexes , or supercomplexes based on size .
in fact , many studies support an approximately scale - free clustering pattern for both the gas and stars in galaxies , a behavior typically attributed to the turbulent cascade of energy within the gas ( see elmegreen & scalo 2004 for a review ) . a quantitative description of stellar clustering including the identification of any characteristic scales
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Suppose that you have an abstract for a scientific paper: we study electronic and magnetic properties of the quasi - one - dimensional spin-@xmath0 magnet ba@xmath1cu@xmath1sc@xmath2o@xmath3 with a distinct orthogonal connectivity of cuo@xmath4 plaquettes .
an effective low - energy model taking into account spin - orbit coupling was constructed by means of first - principles calculations . on this basis a complete microscopic magnetic model of ba@xmath1cu@xmath1sc@xmath2o@xmath3 , including symmetric and antisymmetric anisotropic exchange interactions , is derived .
the anisotropic exchanges are obtained from a distinct first - principles numerical scheme combining , on one hand , the local density approximation taking into account spin - orbit coupling , and , on the other hand , projection procedure along with the microscopic theory by toru moriya .
the resulting tensors of the symmetric anisotropy favor collinear magnetic order along the structural chains with the leading ferromagnetic coupling @xmath5mev .
the interchain interactions @xmath6mev and @xmath7mev are antiferromagnetic .
quantum monte carlo simulations demonstrated that the proposed model reproduces the experimental neel temperature , magnetization and magnetic susceptibility data .
the modeling of neutron diffraction data reveals an important role of the covalent cu
o bonding in ba@xmath1cu@xmath1sc@xmath2o@xmath3 . .
And you have already written the first three sentences of the full article: the cuo@xmath4 plaquette is the key structural element in the majority of low - dimensional copper oxides @xcite . ideally , it consists of the cu atom at the center of the square formed by four oxygen atoms .
the valence 2 + of the cu ion corresponds to the atomic configuration in which all @xmath8 orbitals are fully occupied except that of the @xmath9 symmetry containing one unpaired electron and having the highest energy .
such a geometry leads to a strong hybridization between the @xmath9 states of cu and @xmath10 states of oxygen , which affects magnetic properties of low - dimensional cuprates ..
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for instance , spin density is largely delocalized and spread over the plaquette .
this effect should be taken into account when analyzing the data from neutron scattering @xcite .
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Suppose that you have an abstract for a scientific paper: intrinsic electron spin relaxation due to the dyakonov - perel mechanism is studied in monolayer molybdenum disulphide .
an intervalley in - plane spin relaxation channel is revealed due to the opposite effective magnetic fields perpendicular to the monolayer molybdenum disulphide plane in the two valleys together with the intervalley electron - phonon scattering .
the intervalley electron - phonon scattering is always in the weak scattering limit , which leads to a rapid decrease of the in - plane spin relaxation time with increasing temperature .
a decrease of the in - plane spin relaxation time with the increase of the electron density is also shown . .
And you have already written the first three sentences of the full article: transition - metal dichalcogenides , similar to graphite , are layered materials with weak interlayer van der waals interaction .
these materials can be exfoliated to single to few - layer samples as the fabrication of graphene.@xcite among these samples , monolayer molybdenum disulphide ( mos@xmath0 ) has received much attention due to its distinctive properties.@xcite it has a direct gap at the inequivalent k and k@xmath1 points,@xcite which makes it attractive as a two - dimensional channel material in field - effect transistors .
very recently , the field - effect transistor devices based on monolayer mos@xmath0 have been realized in the experiments with high on - off ratio.@xcite in addition , space inversion symmetry is broken in monolayer mos@xmath0 since it is a two - dimensional hexagonal lattice consisted of two different sublattices , i.e. , mo and s atoms ..
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the absence of the space inversion symmetry results in a valley - dependent optical selection rule for interband transitions , which allows the realization of the valley polarization by optical pumping with circularly polarized light.@xcite space inversion symmetry breaking can also induce spin splitting of both the conduction and valence bands where the one of the valence band is much larger than that of the conduction band.@xcite this spin splitting is essential for spin physics and spintronic applications .
all these intriguing features make monolayer mos@xmath0 of particular interest . as spin relaxation is crucial for possible realistic spintronic applications ,
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Suppose that you have an abstract for a scientific paper: the objective of this research was to identify factors affecting tree damage in the historical minot flood of 2011 .
we hypothesized that tree height , identity , origin , and maximum water height affect in the severity of damage sustained by a tree in a flood event .
all these factors were significant but highly interactive .
the results from this research can influence planting practices in valleys and other flood prone areas to mitigate future damage . .
And you have already written the first three sentences of the full article: various effects of flooding can drastically alter an ecosystem . some of the factors that could potentially harm trees include alteration of soil factors , disturbance of plant life , and degeneration of habitat . during a flood , soil is altered by erosion , deoxygenation , and reconfiguration ( kozlowski 1997 ; lake 2011 ) .
erosion is caused by the continuous circular and turbulent motion of the water .
this motion carries particles of the soil away , resulting in a loss of topsoil , loss of nutrients , and an exposure of plant roots ; all three of these factors severely harm plants ( shafroth et al ..
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the topsoil is reconfigured with the finer particles that were carried with the flood , such as sand and silt , which may to compact into finer arrangements .
this compacted soil restricts the ability to hold gases such as oxygen , causing deoxygenation of the soil ( parrett 1964 ) .
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Suppose that you have an abstract for a scientific paper: in this paper we address the temporal energy growth associated with numerical approximations of the perfectly matched layer ( pml ) for maxwell s equations in first order form . in the literature
, several studies have shown that a numerical method which is stable in the absence of the pml can become unstable when the pml is introduced .
we demonstrate in this paper that this instability can be directly related to numerical treatment of boundary conditions in the pml .
first , at the continuous level , we establish the stability of the constant coefficient initial boundary value problem for the pml . to enable the construction of stable numerical boundary procedures
, we derive energy estimates for the variable coefficient pml .
second , we develop a high order accurate and stable numerical approximation for the pml using summation by parts finite difference operators to approximate spatial derivatives and weak enforcement of boundary conditions using penalties . by constructing analogous discrete energy estimates
we show discrete stability and convergence of the numerical method .
numerical experiments verify the theoretical results .
maxwell s equations , guided waves , boundary waves , normal mode analysis , perfectly matched layers , energy method , well
posedness , stability , high order accuracy , efficiency , finite difference , summation by parts , penalty terms .
35l15 35l05 35l10 35l20 35q61 35q74 .
And you have already written the first three sentences of the full article: numerical approximations of the perfectly matched layer ( pml ) @xcite for maxwell s equations in first order form often exhibit a late time linear or exponential energy growth , see for example @xcite .
this unwanted growth can spread into the computational domain and ruin the accuracy of a numerical simulation .
growth is often seen long after a wave has exited the domain or when a wave has been trapped in the domain for a longtime ..
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the later situation can occur , for example , in the simulation of an electromagnetic waveguide . this has generated substantial interests .
one explanation for this behavior of the pml was offered in @xcite .
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Suppose that you have an abstract for a scientific paper: in this note we present a review of the little higgs models that stabilize the electroweak by realizing the standard model higgs as a pseudo - goldstone boson . .
And you have already written the first three sentences of the full article: the experimental results of the past decade indicate that the chiral lagrangian describing ewsb works to one loop accuracy and irrelevant operators ( such as @xmath0 , where @xmath1 are the goldstone bosons eaten by @xmath2 and @xmath3 ) are suppressed by a scale @xmath4 .
this strongly indicates perturbative physics at @xmath5 and a physical higgs boson @xmath6 .
however , this linear sigma model is unstable to quantum corrections leading to the hierarchy problem , meaning that the standard model is in an incomplete description of physics parametrically above the weak scale . to date.
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, only the mssm provides a solution to the hierarchy problem and weakly coupled physics at 1 tev . in this note
we review models where the higgs is a pseudo - goldstone boson , @xmath7 @xcite , for early attempts see @xcite .
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Suppose that you have an abstract for a scientific paper: the opera experiment in the underground gran sasso laboratory ( lngs ) has been designed to perform the first detection of neutrino oscillations in direct appearance mode in the muon neutrino to tau neutrino channel .
the detector is hybrid , being made of an emulsion / lead target and of electronic detectors .
it is placed in the cngs neutrino beam 730 @xmath0 away from the neutrino source .
runs with cngs neutrinos were successfully carried out in 2008 , 2009 , and 2010 . after a brief description of the beam and the experimental setup
, we report on event analysis of a sample of events corresponding to @xmath1 @xmath2 in the cern cngs @xmath3 beam that yielded the observation of a first candidate @xmath4 cc interaction .
the topology and kinematics of this candidate event are described in detail .
the background sources are explained and the significance of the candidate is assessed .
[ 1999/12/01 v1.4c il nuovo cimento ] .
And you have already written the first three sentences of the full article: two types of experimental methods can be used to detect neutrino oscillations : observing the appearance of a neutrino flavour initially absent in the beam or measuring the disappearance rate of the initial flavour . in the latter case , one must know the flux of the beam precisely . in this type of experiment one
explores whether less than the expected number of neutrinos of a produced flavour arrives at a detector or whether the spectral shape changes if observed at various distances from a source .
since the final state is not observed , disappearance experiments can not tell into which flavor a neutrino has oscillated ..
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an appearance experiment searches for possible new flavours of neutrino , which does not exist in the original beam , or for an enhancement of an existing neutrino flavour .
the identification of the flavour relies on the detection of the corresponding lepton produced in its charged current ( cc ) interactions : @xmath5 with @xmath6 and where x denotes the hadronic final state . in the past two decades ,
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Suppose that you have an abstract for a scientific paper: researchers try to model the aesthetic quality of photographs into low and high - level features , drawing inspiration from art theory , psychology and marketing .
we attempt to describe every feature extraction measure employed in the above process .
the contribution of this literature review is the taxonomy of each feature by its implementation complexity , considering real - world applications and integration in mobile apps and digital cameras . also , we discuss the machine learning results along with some unexplored research areas as future work . image processing , feature extraction , photograph quality assessment .
And you have already written the first three sentences of the full article: quality assessment of photographs is not a new issue arising with digital cameras .
birkhoff , back in 1933 proposed that the aesthetic appeal of objects relates to the ratio of order and complexity in images .
the hardness in this task is to define order and complexity [ 4 ] . with the advent of digital cameras and smartphones ,.
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people capture more photographs than they can consume . nowadays
, social media provide an adequate filter of our social graph , displaying to us photographs and posts by our friends or friends of friends , based on popularity metrics .
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Suppose that you have an abstract for a scientific paper: a new parameterization for the dark energy equation of state(eos ) is proposed and some of its cosmological consequences are also investigated .
this new parameterization is the modification of efstathiou dark energy eos parameterization .
@xmath0 is a well behaved function for @xmath1 and has same behavior in @xmath2 at low redshifts with efstathiou parameterization . in this parameterization
there are two free parameter @xmath3 and @xmath4 .
we discuss the constraints on this model s parameters from current observational data .
the best fit values of the cosmological parameters with @xmath5 confidence - level regions are : @xmath6 , @xmath7 and @xmath8 . .
And you have already written the first three sentences of the full article: in recent years , the discovery of accelerating expansion of the universe is an amazing development .
it was firstly discovered by observing type ia supernova ( sne ia ) @xcite , which can be used as standard candles @xcite . the cosmic microwave background ( cmb )
measurements from wilkinson microwave anisotropy probe ( wmap ) @xcite and the large scale structure survey by sloan digital sky survey ( sdss ) @xcite confirm this accelerating expansion universe model ..
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there are two kinds of ideas , i.e. the existence of the dark energy or modifications of the gravity theory , to explain this concept .
the first scheme is most popularly discussed , and many models have been proposed , such as the holographic dark energy models @xcite and the chaplygin gas @xcite .
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Suppose that you have an abstract for a scientific paper: we describe a computational proof that the fifth secant variety of the segre product of five copies of the projective line is a codimension @xmath0 complete intersection of equations of degree @xmath1 and @xmath2 .
our computations rely on pseudo - randomness , and numerical accuracy , so parts of our proof are only valid `` with high probability '' . .
And you have already written the first three sentences of the full article: secant varieties have received growing attention in recent times , largely because of the fact that they provide a geometric model relevant to a wide variety of applications .
the purpose of this note is to provide a case study in finding equations of secant varieties . for an introduction to secant varieties and their applications
we invite the reader to consult @xcite and the vast collection of references therein ..
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the 5 factor binary secant variety is particularly interesting in light of recent results of bocci and chiantini @xcite , that @xmath3 tensors are not identifiable in rank 5 , but the generic tensor of that format has exactly 2 decompositions . for @xmath4 factors ,
the binary segre product is known to be @xmath5-identifiable for most of the possible values of @xmath5 below the generic rank , see @xcite and @xcite .
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Suppose that you have an abstract for a scientific paper: we consider ` brane universe ' scenarios with standard - model fields localized on a 3-brane in 6 spacetime dimensions .
we show that if the spacetime is rotationally symmetric about the brane , local quantities in the bulk are insensitive to the couplings on the brane .
this potentially allows compactifications where the effective 4-dimensional cosmological constant is independent of the couplings on the 3-brane .
we consider several possible singularity - free compactification mechanisms , and find that they do not maintain this property .
we also find solutions with naked spacetime singularities , and we speculate that new short - distance physics can become important near the singularities and allow a compactification with the desired properties . the picture that emerges is that standard - model loop contributions to the effective 4-dimensional cosmological constant can be cut off at distances shorter than the compactification scale . at shorter distance scales ,
renormalization effects due to standard - model fields renormalize the 3-brane tension , which changes a deficit angle in the transverse space without affecting local quantities in the bulk . for a compactification scale of order @xmath0
, this gives a standard - model contribution to the cosmological constant in the range favored by cosmology . .
And you have already written the first three sentences of the full article: the cosmological constant problem is by far the most severe fine - tuning problem in physics . despite many interesting proposals ( see for a review ) the problem still lacks a compelling solution .
recently , there has been an interesting idea in the context of the ` brane universe ' scenario that may solve part of the cosmological constant problem , namely the sensitivity of the effective low - energy cosmological constant to standard - model radiative corrections @xcite . in this proposal the standard - model fields
are assumed to be localized on a 3-brane in 5 spacetime dimensions ..
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it was argued in that special bulk - brane interactions can be chosen so that solutions with unbroken 4-dimensional poincar invariance exist independently of the standard model parameters and the 3-brane tension .
the solutions found in have a naked spacetime singularity , whose resolution in a more fundamental theory of gravity was argued to play an important role in this scenario . on the other hand ,
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Suppose that you have an abstract for a scientific paper: two generically different but universal dynamical quantum many - body behaviors are discovered by probing the stability of trapped fragmented bosonic systems with strong repulsive finite / long range inter - particle interactions .
we use different time - dependent processes to destabilize the systems a sudden displacement of the trap is accompanied by a sudden quench of the strength of the inter - particle repulsion .
a rather moderate non - violent evolution of the density in the first `` topology - preserved '' scenario is contrasted with a highly - non - equilibrium dynamics characterizing an explosive changes of the density profiles in the second scenario .
the many - body physics behind is identified and interpreted in terms of self - induced time - dependent barriers governing the respective under- and over - a - barrier dynamical evolutions .
the universality of the discovered scenarios is explicitly confirmed in 1d , 2d and 3d many - body computations in ( a)symmetric traps and repulsive finite / long range inter - particle interaction potentials of different shapes .
implications are briefly discussed .
one of the most bright universal features shared by many - body systems with strong repulsive interaction is the formation of multi - hump structures in the ground states densities .
driven by the strong repulsive interaction they can be formed in the systems with short- and finite / long - range inter - particle interactions in one- ( 1d ) , two- ( 2d ) and three - dimensional ( 3d ) setups .
the famous examples in the context of ultra - cold systems are strong contact interaction and tonks - girardeu gases in 1d @xcite and in more general physical contents the formation of super - solids and crystals in 2d systems with long - range interactions @xcite . while ground state properties of these systems have been accessed at different levels of the quantum theory , the many - body studies on excited states , needed to digest dynamical behavior and stability of these systems are....
And you have already written the first three sentences of the full article: in this supplementary material we first show that the inter - particle interaction of the @xmath35 shape , used throughout the present study , appears naturally in the context of the `` rydberg - dressed '' atoms .
so , it is possible to verify all the predicted physics within presently available experimental setups .
next , we demonstrate how to control the number of humps and fragmentation ratio in the ground state of the bosonic system with such an inter - particle interaction trapped in simple barrier - less traps , also see ref ..
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we also show how to distinguish fragmented systems studied here from the condensed ones , by means of the correlation functions .
finally , we provide the full movies of the time - dependent evolutions in 2d and 3d setups , discussed in the main text .
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Suppose that you have an abstract for a scientific paper: transitional pipe flow is modeled as a one - dimensional excitable and bistable medium .
models are presented in two variables , turbulence intensity and mean shear , that evolve according to established properties of transitional turbulence .
a continuous model captures the essence of the puff - slug transition as a change from excitability to bistability . a discrete model , that additionally incorporates turbulence locally as a chaotic repeller , reproduces almost all large - scale features of transitional pipe flow .
in particular it captures metastable localized puffs , puff splitting , slugs , a continuous transition to sustained turbulence via spatiotemporal intermittency ( directed percolation ) , and a subsequent increase in turbulence fraction towards uniform , featureless turbulence .
the transition to turbulence in pipe flow has been the subject of study for over 100 years @xcite , both because of its fundamental role in fluid mechanics and because of the detrimental consequences of turbulent transition in many practical situations .
there are at least two features of the problem that make it fascinating , but also difficult to analyze .
the first is that when turbulence appears , it appears abruptly @xcite , and not through a sequence of transitions each increasing the dynamical complexity of the flow .
turbulence is triggered by finite - sized disturbances to linearly stable laminar flow @xcite .
this hysteretic , or subcritical , aspect of the problem limits the applicability of linear and weakly nonlinear theories .
the second complicating feature is the intermittent form turbulence takes in the transitional regime near the minimum reynolds number ( non - dimensional flow rate ) for which turbulence is observed @xcite . in sufficiently long pipes , localized patches of turbulence ( puffs ) may persist for extremely long times before abruptly reverting to laminar flow @xcite .
in other cases , turbulent patches may spread by contaminating nearby laminar flow ( puff....
And you have already written the first three sentences of the full article: here the parameter selection used in this study is discussed .
no attempt has been made to determine precisely values such for the best fit to pipe flow .
the models are not sufficiently quantitative that exact comparisons are called for at this time ..
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moreover , the phenomena presented in the paper are very robust and for some parameters there simply is not a strong criterion to use to select precise values . the goal is to provide justification for the values used in the paper as well as insight into how the parameters control the dynamics of the models
. only the two rates @xmath24 and @xmath26 need to be determined .
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Suppose that you have an abstract for a scientific paper: based upon the bonn meson - exchange - model for the nucleon - nucleon ( @xmath0 ) interaction , we calculate the charge - independence breaking ( cib ) of the @xmath0 interaction due to pion - mass splitting . besides the one - pion - exchange ( ope ) , we take into account the @xmath1-exchange model and contributions from three and four irreducible pion exchanges .
we calculate the cib differences in the @xmath2 effective range parameters as well as phase shift differences for partial waves up to total angular momentum @xmath3 and laboratory energies below 300 mev .
we find that the cib effect from ope dominates in all partial waves .
however , the cib effects from the @xmath1 model are noticable up to d - waves and amount to about 40% of the ope cib - contribution in some partial waves , at 300 mev .
the effects from 3@xmath4 and 4@xmath4 contributions are negligible except in @xmath2 and @xmath5 . .
And you have already written the first three sentences of the full article: it is well known that isospin invariance is not an exact symmetry of strong interactions . consequently , nuclear forces have a small but measurable charge - dependent component . the equality between proton - proton ( @xmath6 ) [ or neutron - neutron ( @xmath7 ) ] and neutron - proton ( @xmath8 ) nuclear interactions
is known as charge independence .
charge - independence breaking ( cib ) is seen most clearly in the @xmath2 nucleon - nucleon ( @xmath0 ) scattering lengths ..
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the latest empirical values for the singlet scattering length @xmath9 and effective range @xmath10 are @xcite : @xmath11 the values given for @xmath6 and @xmath7 scattering refer to the nuclear part of the interaction as indicated by the superscript @xmath12 .
electromagnetic effects have been removed from the experimental values , which is model dependent .
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Suppose that you have an abstract for a scientific paper: collisions of ice particles play an important role in the formation of planetesimals and comets . in recent work we showed , that co@xmath0 ice behaves like silicates in collisions .
the resulting assumption was that it should therefore stick less efficiently than h@xmath0o ice . within this paper a quantification of the latter
is presented .
we used the same experimental setup to study collisions of pure co@xmath0 ice , pure water ice and 50% mixtures by mass between co@xmath0 and water at 80k , 1 mbar and an average particle size of @xmath1 m .
the results show a strong increase of the threshold velocity between sticking and bouncing with increasing water content .
this supports the idea that water ice is favorable for early growth phases of planets in a zone within the h@xmath0o and the co@xmath0 iceline . .
And you have already written the first three sentences of the full article: ices are important constituents in the collisional formation of comets and planetesimals in protoplanetary disks .
as various species of ice appear in different distances to the central star due to their individual sublimation pressures , there are various icelines within the disk .
planet formation in general but especially collision outcomes are tied to these icelines and the physics of the prevailing kind of ice . @xcite . in earlier experiments we showed that it is necessary to distinguish the different ices while studying their growth potential @xcite ..
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we suggested that collisional growth should be most efficient between the water and the co@xmath0 iceline or between 2.0 to 9.3 au according to the minimum mass solar nebula model .
beyond 9.3 au non - polar co@xmath0 dominates .
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Suppose that you have an abstract for a scientific paper: the major multi - epoch vlba programs are described and discussed in terms of relativistic beaming models . broadly speaking the observed kinematics are consistent with models having a parent population which is only mildly relativistic but with lorentz factors extending up to about 30 .
while the collimation and acceleration appears to mainly occur close to the central engine , there is evidence of accelerations up to 1 kpc downstream .
generally the motion appears to be linear , but in some sources the motion follows a curved trajectory . in other sources ,
successive features appear to be ejected in different directions possibly the result of a precessing nozzle .
the launch of glast in 2008 will offer new opportunities to study the relation between radio and gamma ray activity , and possibly to locate the source of the gamma ray emission .
vsop-2 will give enhanced resolution and will facilitate the study of the two - dimensional structure of relativistic jets , while radioastron will provide unprecedented resolution to study the fine scale structure of the jet base . .
And you have already written the first three sentences of the full article: as discussed earlier in this conference by dave meier , the theoretical framework for the formation of relativistic jets due to the accretion of matter onto a supermasive black hole is well developed .
observations of jet kinematics obtained by multi - epoch high resolution imaging provides tests of theoretical models and can constrain the parameters of the jet formation . however , the interpretation is not straightforward .
the observations do not give instantaneous multi - epoch snapshots of the source structure ..
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rather , due to relativistic effects , different parts of the source are observed at different times , giving the illusion of superluminal motion , the distortion of angles and misrepresentation of luminosity . in particular , the observed speeds and luminosities of jets are highly biased due to doppler boosting within a narrow cone , and they are not representative of the intrinsic distributions .
finally , we note that apparent speeds derived from multi - epoch vlbi observations refer to the observed motion of recognizable features , typically referred to as `` components , '' which do not necessarily reflect the underlying bulk relativistic flow , but which instead may simply reflect the propagation of forward and reverse shocks within the jet flow .
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Suppose that you have an abstract for a scientific paper: an overview of pulsating variable stars across the observational hertzprung - russel ( hr ) diagram is presented , together with a summary of their global properties .
the hr diagram is presented with a third colour - coded dimension , visualizing the fraction of variable , the amplitude of variability or the period of variability .
the distribution of variable stars in the other observational diagrams , such as the period - amplitude diagram , is also presented .
some of the progresses performed in the field of variable stars during the last decade are briefly summarized , and future projects that will improve our knowledge of variable stars are mentioned . .
And you have already written the first three sentences of the full article: there are in the literature several global descriptions of variable stars .
we can mention four books , one by richter , wenzel and hoffmeister ( 1985 , out of print ) , one by sterken and jaschek @xcite , one by percy ( @xcite ) and one , soon to come , by aerts et al .
there have also been two excellent and detailed reviews by gautschy and saio ( @xcite , @xcite ) about a decade ago . with the advent of charge - coupled devices ( ccds ) and large scale surveys like the optical gravitational lensing experiment ( ogle ) ,.
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the massive compact halo object project ( macho ) or the `` exprience pour la recherche dobjets sombres '' ( eros ) , the subject of variable star studies is now under a remarkable expansion . as we will see
the expansion will continue in the coming decade because there are many future projects which will sample frequently large regions of the sky .
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Suppose that you have an abstract for a scientific paper: we introduce a bayesian solution to the problem of inferring the density profile of strong gravitational lenses when the lens galaxy may contain multiple dark or faint substructures .
the source and lens models are based on a superposition of an unknown number of non - negative basis functions ( or `` blobs '' ) whose form was chosen with speed as a primary criterion .
the prior distribution for the blobs properties is specified hierarchically , so the mass function of substructures is a natural output of the method .
we use reversible jump markov chain monte carlo ( mcmc ) within diffusive nested sampling ( dns ) to sample the posterior distribution and evaluate the marginal likelihood of the model , including the summation over the unknown number of blobs in the source and the lens .
we demonstrate the method on two simulated data sets : one with a single substructure , and one with ten .
we also apply the method to the g - band image of the `` cosmic horseshoe '' system , and find evidence for more than zero substructures . however , these have large spatial extent and probably only point to misspecifications in the model ( such as the shape of the smooth lens component or the point spread function ) , which are difficult to guard against in full generality . [ firstpage ] gravitational lensing : strong methods : data analysis methods : statistical .
And you have already written the first three sentences of the full article: galaxy - galaxy gravitational lensing is a powerful astrophysical tool for studying the distribution of matter , including dark matter , in galaxies @xcite
. one promising application of lensing is to study and measure the properties of dark matter substructures in the lens galaxy @xcite . in recent years
, this promise has been realised in several lens systems which are thought to contain at least one dark substructure @xcite . in these studies ,.
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the lens was modelled as a superposition of a smooth component ( such as an elliptical power - law matter distribution ) plus a pixellized `` non - parametric '' correction term .
the estimated spatial structure of the correction term provides clues about the locations of possible substructures . in a second modelling step ,
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Suppose that you have an abstract for a scientific paper: in this paper we report the _ fermi _ large area telescope ( lat ) detection of very high energy ( vhe ; @xmath0 gev ) @xmath1-ray emission from the bl lac object rbs 0679 .
5.3 years of lat observations revealed the presence of three vhe photon events within [email protected] of rbs 0679 , with a subsequent unbinned likelihood analysis finding rbs 0679 to be a source of vhe photons at @xmath3 standard deviations ( @xmath4 ) .
an unbinned likelihood analysis of the @xmath5 gev data , binned in 28-day periods , finds both the flux and spectral index to be variable , with a ` softer - when - brighter ' trend in the global @xmath1-ray characteristics . on the other hand ,
the 28-day periods in which the vhe photons were detected have spectral indices that are consistent with the 5.3 year average suggesting that the observed vhe emission is not associated with a spectral hardening event .
the discovery of rbs 0679 in the @xmath6 gev energy range , combined with the non - detection above 390 gev with the h.e.s.s . telescope array , suggest rbs 0679 to be an intriguing source that requires further follow - up observations with ground - based @xmath1-ray observatories .
[ firstpage ] radiation : non - thermal galaxies : active bl lacertae individual ( rbs 0679 ) galaxies : jets gamma rays : galaxies . .
And you have already written the first three sentences of the full article: launched in june 2008 , the _ fermi _
@xmath1-ray space telescope affords an ideal opportunity to investigate the inner workings of active galactic nuclei ( agn ) . to date , _ fermi _ has spent over 95% of its lifetime in _ all - sky - survey _ observing mode , whereby the large area telescope ( lat ) onboard _ fermi _ points away from the earth and rocks north and south of its orbital plane on consecutive orbits .
this rocking motion of the _ fermi_-lat detector , coupled with it s large effective area , allows _.
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fermi _ to scan the entire @xmath1-ray sky every two orbits , or approximately every three hours ( @xcite ) .
the scanning ability of the lat has allowed us to catch agn during brief flares of @xmath1-ray activity ( e.g. @xcite ) , with these flares sometimes resulting in the discovery of very high energy ( vhe ; @xmath0 gev ) emission from the agn ( e.g. @xcite & @xcite ) . while its three hour scan period is important for catching brief periods of flare activity from agn , coupling _
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Suppose that you have an abstract for a scientific paper: the diagram is resurrected to dramatically illustrate the nature of the key problems in physical cosmology today and the role that nuclear physics plays in many of them . in particular it is noted that the constraints on from big bang nucleosynthesis do not overlap with the constraints on nor have significant overlap with the lower bound on @xmath0 from cluster studies .
the former implies that the bulk of the baryons are dark and the later is the principle argument for non - baryonic dark matter .
a comparison with hot x - ray emitting gas in clusters is also made .
the lower bound on the age of the universe from globular cluster ages ( hydrogen burning in low mass stars ) and from nucleocosmochronology also illustrates the hubble constant requirement @xmath1 for @xmath2 .
it is also noted that high values of @xmath3 ( @xmath4 ) even more strongly require the presence of non - baryonic dark matter
. the lower limit on @xmath3 ( @xmath5 ) from carbon detonation driven type ia supernova constrains long ages and only marginally allows to overlap with .
diagrams of for @xmath6 and @xmath7 are presented to show that the need for non - baryonic dark matter is independent of @xmath8 .
= = 6.5 in = -0.5 in # 1 [ # 1 ] # 110^#1 @xmath9 # 1@xmath10 # 1#1@xmath11 # 1#2 # 1#2 # 1 # 1#1 .
+ # 1#23.6pt @bibitem = bibitem bibitem#1#2ifundefinedr@#1warning multiple entries for reference ` # 1'ifundefinedb@#1warning reference ` # 1 ' not citednamedefr@#1#2 @lbibitem = lbibitem lbibitem[#1]#2#3ifundefinedr@#2warning multiple entries for reference ` # 2'ifundefinedb@#2warning reference ` # 2 ' not citednamedefr@#2#3
namedefs@#2#1 putbibrefs#1makearef # 1 * , makearef#1,#1 = = makearef ifundefineds@#1 ifundefinedr@#1citation label ` # 1'?nameuser@#1 citex[#1]#2@fileswauxout citeaciteforciteb:=#2#1 # 1ifundefinedd@#1addlabel#1warning label ` # 1 ' cited . not necessary .
addlabel#1ifundefined@bibrefslistbibrefslist#1 , bibrefslistbibrefslist#1 , @cite = cite....
And you have already written the first three sentences of the full article: 40004000 = 1000 # 10=to 0.50#1msf= msf=1000 0.35 in the nuclear impact on cosmology : the diagram 0.2 in craig j. copi@xmath13 and david n. schramm@xmath14 0.2 in _
@xmath15department of physics + the university of chicago , chicago , il 60637 - 1433 _ + 0.1 in _ @xmath16nasa / fermilab astrophysics center + fermi national accelerator laboratory , batavia , il 60510 - 0500 _ + 0.1 in _
@xmath17department of astronomy & astrophysics + enrico fermi institute , the university of chicago , chicago , il 60637 - 1433 _ +.
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in 1974 , gott , gunn , schramm , and tinsley ( hereafter , ggst ) showed that a plot of the hubble constant , @xmath3 , verse the the dimensionless density parameter , , [ eqn : omega ] where @xmath18 is the mass density and = is the critical cosmological density , well illustrated the issues in physical cosmology , particularly for models with cosmological constant @xmath19 .
twenty years later we again use the diagram and show that the constraints of ggst have not changed significantly but the interpretation now illustrates the critical issues in physical cosmology today , namely the dark matter and age problems . as nuclear / particle astrophysicists we note with pride ( or fear ) how many of the most significant lines on the diagram have their origin in nuclear physics arguments .
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Suppose that you have an abstract for a scientific paper: we present the incident energy and system size dependence of the @xmath0 spectra for @xmath1 , @xmath2 , and @xmath3 using au+au and cu+cu collisions at @xmath4 = 62.4 and 200 gev in star experiment at rhic . through these measurements in the @xmath0 range of 0.2 @xmath5 @xmath0
@xmath5 10 gev/@xmath6 we conduct a systematic study of the beam energy , system size and particle species dependence of nuclear modification factors and address specific predictions from the quark coalescence models regarding the beam energy dependence of baryon enhancement in the intermediate @xmath0 ( 2 @xmath5 @xmath0 @xmath5 6 gev/@xmath6 ) region . .
And you have already written the first three sentences of the full article: a detailed study of the beam energy ( @xmath4 ) , transverse momentum ( @xmath0 ) and system size dependence of identified hadron production will provide the necessary data to understand the mechanism of energy loss , and put constraints on parameters in energy loss model calculations like initial gluon density @xcite and life time of dense matter @xcite .
they will also help in probing the difference in the energy loss of quarks and gluons in the medium @xcite .
the energy dependence of baryon to meson ratio at the intermediate @xmath0 region from 2 - 6 gev/@xmath6 will address the specific prediction from the quark coalescence models of a higher baryon to meson ratio at @xmath4 = 62.4 gev compared to @xmath4 = 200 gev @xcite . at high @xmath0 ( @xmath7 6 gev/@xmath6 ).
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the @xmath2/@xmath8 ratio can provide information on quark and gluon jet conversions in the medium formed in heavy ion collisions @xcite .
the data presented here are obtained from the time projection chamber ( tpc ) and the time - of - flight ( tof ) detector in the star experiment @xcite at rhic in the year 2004 .
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Suppose that you have an abstract for a scientific paper: we investigate fuse spectra of three pg1159 stars and do not find any evidence for iron lines . from a comparison with nlte models we conclude a deficiency of 11.5dex .
we speculate that iron was transformed into heavier elements .
a soft x - ray chandra spectrum of the unique h- and he - deficient star h1504 + 65 is analyzed .
we find high neon and magnesium abundances and confirm that h1504 + 65 is the bare core of either a c - o or a o - ne - mg white dwarf . .
And you have already written the first three sentences of the full article: the origin of hot hydrogen - deficient post - agb stars ( spectral types [ wc ] and pg1159 ) is supposed to be a late he - shell flash .
detailed summaries on their spectroscopic characteristics and quantitative analyses , and relevant evolutionary calculations can be found e.g. in werner ( 2001 ) and herwig ( 2001 ) , respectively . in the last white dwarf workshop , held in delaware two years ago , we presented for the first time clear evidence for iron deficiency in a pg1159 star ( miksa 2001 )
. because pg1159 central stars are very hot ( @xmath075000k ) , the metals are highly ionized ..
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the dominant ionization stage of iron in the line formation region is and most of its lines are located in the fuv spectral region .
contrary to our expectation we were not able to detect any line in the fuse fuv spectrum of the pulsating central star of k1 - 16 , which means that iron is deficient by at least one dex .
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Suppose that you have an abstract for a scientific paper: a study of the ultraviolet continuum variability ( paltani & courvoisier @xcite ) has shown that the relative variability of quasars and seyfert galaxies decreases when the luminosity increases .
the spectral information included in the iue spectra allows us to study this dependence in the rest frame of the objects .
the trend is strengthened by the general property that active galactic nuclei vary more at short wavelengths than at long wavelengths in the ultraviolet domain .
the scatter observed in all other studies is still present .
an important part of this scatter may however be explained if one tries to estimate the uncertainties on the variability due to the sampling .
we discuss the variability using the concept of discrete events .
the trend between variability and luminosity is described by a power - law with an index @xmath0 , which is incompatible with the power - law of index @xmath1 predicted by the most general discrete - event models in which the change in average luminosity is due to differences in average event rates exclusively .
several biases are investigated , but we conclude that the @xmath1 index is definitely inconsistent with the data .
a flat relationship is however possible , if some bias has been underestimated .
we propose different ways whereby discrete events may produce a different variability
luminosity relationship : by changing the luminosity or the life time of the events , or by introducing interdependence between the events .
the latter possibility can not produce a satisfactory relationship .
using the former possibilities , we do not find any `` natural '' explanation for the variability
luminosity relationship in the context of discrete - event models .
this is possibly an indication that explanations in which variability is not expressed in terms of discrete events should be favoured . .
And you have already written the first three sentences of the full article: the statistical properties of the ultraviolet variability of active galactic nuclei ( agn ) have been investigated by paltani & courvoisier ( @xcite ) ( hereafter pc94 ) .
this study , which was based on spectra obtained by the _ international ultraviolet explorer _ ( iue ) from the ulda ( _ uniform low dispersion archive _ ) database , has been done in the observer s frame .
in addition to the variability at 2000 , we quantified also the change of variability with the wavelength , which showed that all classes of agn have a larger variability at short wavelength than at long wavelength in the iue domain . in this paper.
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we shall consider only the objects that have been called in pc94 , i.e. seyfert 1 galaxies , radio - quiet quasars , and low - polarization radio - loud quasars .
the relationship between variability and luminosity in quasars and seyfert galaxies has been investigated by many authors .
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Suppose that you have an abstract for a scientific paper: in this paper we introduce a ltb - bianchi i ( plane symmetric ) model of universe .
we study and solve einstein field equations .
we investigate the effects of such model of universe in particular these results are important in understanding the effect of the combined presence of an inhomogeneous and anisotropic universe .
the observational magnitude - redshift data deviated from union 2 catalog has been analyzed in the framework of this ltb - anisotropic universe and the fit has been achieved without the inclusion of any dark energy . .
And you have already written the first three sentences of the full article: a very important assumption of the standard model of cosmology ( @xmath0 ) is based on the homogeneous and isotropic friedmann - lemaitre - robertson - walker solutions of einstein s equations . the homogeneity and the isotropy
are considered on large scale in the universe .
the universe is not isotropic or spatially homogeneus on local scales . the question of whether the universe is homogeneous and isotropic is of fundamental importance to cosmology , but we have not decisive answers . on the other hand.
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neither observations of luminosity distance combinated with galaxy number counts nor isotropic cosmic microwave background radiation are able to say if the universe is spatially homogeneous and isotropic .
the fundamental question consists in a simple observation : this geometry is the only that is able to explain and to be compatible with experimental data ?
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Suppose that you have an abstract for a scientific paper: we present a generalization of the hyperspherical harmonic formalism to study systems made of quarks and antiquarks of the same flavor .
this generalization is based on the symmetrization of the @xmath0body wave function with respect to the symmetric group using the barnea and novoselsky algorithm .
the formalism is applied to study four - quark systems by means of a constituent quark model successful in the description of the two- and three - quark systems .
the results are compared to those obtained by means of variational approaches .
our analysis shows that four - quark systems with exotic @xmath1 and non - exotic @xmath2 quantum numbers may be bound independently of the mass of the quark . @xmath3 and
@xmath4 states become attractive only for larger mass of the quarks . .
And you have already written the first three sentences of the full article: the understanding of few - body systems relies in our capability to design methods for finding an exact or approximate solution of the @xmath0body problem . in two- , three- , and four - body problems it is possible to obtain mathematically correct and computationally tractable equations such as the lippmann - schwinger , faddeev and yakubovsky equations describing exactly , for any assumed interaction between the particles , the motion of few - body systems @xcite .
however , the exact solution of these equations requires sophisticated techniques whose difficulty increases when increasing the number of particles .
there are a countless number of examples of quantum - mechanical few - body systems , from few - electron quantum dots in solid state physics to constituent quarks in subnuclear physics ..
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the intricate feature of the few - body systems is that they develop individual characters depending on the number of constituent particles .
the most important cause of these differences are the correlated motion and the pauli principle .
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Suppose that you have an abstract for a scientific paper: artificial gauge fields for neutral particles such as photons , recently attracted a lot of attention in various fields ranging from photonic crystals to ultracold atoms in optical lattices to optomechanical arrays . here
we point out that , among all implementations of gauge fields , the optomechanical setting allows for the most natural extension where the gauge field becomes dynamical .
the mechanical oscillation phases determine the effective artificial magnetic field for the photons , and once these phases are allowed to evolve , they respond to the flow of photons in the structure .
we discuss a simple three - site model where we identify four different regimes of the gauge - field dynamics .
furthermore , we extend the discussion to a two - dimensional lattice .
our proposed scheme could for instance be implemented using optomechanical crystals . *
_ introduction. _ * gauge theories are very elementary concepts in physics . today we know that the fundamental interactions between particles are mediated through gauge fields .
the most common known gauge theory is classical electrodynamics which is described by maxwell s equations . in quantum mechanics the simplest but non trivial setting is a charged quantum particle moving in a classical externally prescribed electromagnetic background field giving rise to phenomena like the aharonov - bohm effect .
field theories such as quantum electrodynamics ( qed ) and quantum chromodynamics ( qcd ) are gauge theories where the gauge fields are dynamical in their own right and which interact with the matter fields , thereby mediating interactions among the matter particles .
recently , intriguing proposals showing how to synthesize dynamical gauge fields have been put forward .
these proposals include the generation of abelian as well as non - abelian gauge fields realized with ultracold atoms in optical lattices @xcite or with superconducting circuits @xcite .
these settings can be viewed as a powerful tool for the quantum simulation....
And you have already written the first three sentences of the full article: here , we give some further details on the three - site model given by eq .
( [ eqn : eq1 ] ) of the main text which in its explicit form reads @xmath95 the equations of motion are obtained straight forwardly by using heisenberg s equation of motion . the mechanical phases
@xmath33 evolve according to @xmath96 the optical amplitudes @xmath97 obey the following equations of motion @xmath98 and the optical phases @xmath99 @xmath100 as mentioned in the main text , for @xmath53 , i.e. , in the case of a static flux @xmath86 , and for @xmath60 a circulator behavior is expected , cf . ref ..
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@xcite . a solution to this system of coupled first order differential equations with initially one photon on site @xmath101 and a phase @xmath79
is shown in fig .
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Suppose that you have an abstract for a scientific paper: this is an invited review talk , presented at the international conference on non - accelerator particle physics ( icnapp-94 ) , bangalore , india , 2 - 9 january 1994 .
6.5 in 8.5 in .25 in # 1#20=1=to0@xmath00=1=to0#2#1 - 01
@=11 tempcntc citex[#1]#2@fileswauxout tempcnta@tempcntb@neciteaciteforciteb:=#2citeo#1 citeotempcnta > tempcntbciteacitea , tempcnta = tempcntbtempcnta
@=12 = cmssbx10 scaled 2 to * solar neutrino oscillations * + r.j.n .
phillips + _ rutherford appleton laboratory , chilton , didcot , oxon ox11 0qx , england _
* 1 .
introduction*. standard solar models ( ssm ) predict the @xmath1 flux of fig.1 with some uncertainties@xcite . measurements by capture in @xmath2 @xcite , @xmath3 scattering@xcite and capture in @xmath4 @xcite , with differing @xmath5 thresholds , find three different deficits : @xmath6 & observation / ssm[2 ] \\
\nu -e & 7.5 mev & 0.51\pm .07\pm .07 & 0.66\pm .09\pm .16 \\ ^{37}cl & 0.81 mev & 0.29\pm .03\pm .04 & 0.36\pm .04\pm .08 \\
^{71}ga & 0.24 mev & 0.62\pm .10\pm .03 & 0.67\pm .11\pm .04 \\ \end{array}\ ] ] where the first error is experimental , the second is from the ssm .
these numbers suggest a differential suppression , with the top and bottom of the accessible range less suppressed than the middle .
they pose the solar neutrino problem 1994 .
re - tuning the solar model gives no easy solution@xcite .
a lower central temperature would suppress @xmath7 production and the @xmath3 rate , but to explain @xmath2 rates the @xmath8 line must then be obliterated - a bit unlikely given that @xmath7 is made from @xmath8 .
neutrino oscillations offer several possible explanations , that i briefly compare . *
2 . long wavelength vacuum oscillations ( lwvo)*. suppose the weak eigenstate @xmath1 , emitted by @xmath9-decays in the sun , is actually a superposition of two mass eigenstates : @xmath10 with @xmath11 .
the mass eigenstates propagate independently with time t , each picking up....
And you have already written the first three sentences of the full article: 1 . solar neutrino spectrum in the ssm [ 1 ] .
2 . typical oscillation factor .
3 . typical lwvo solutions [ 8 ] ..
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eigenvalues of propagation matrix versus density @xmath37 .
5 . the msw bathtub ; suppression factor @xmath95 versus @xmath96 . 6 .
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Suppose that you have an abstract for a scientific paper: the asynchronous systems are the non - deterministic models of the asynchronous circuits from the digital electrical engineering . in the autonomous version ,
such a system is a set of functions @xmath0 called states ( @xmath1 is the time set ) .
if an asynchronous system is defined by making use of a so called generator function @xmath2 then it is called regular .
the property of universality means the greatest in the sense of the inclusion .
the purpose of the paper is that of defining and of characterizing the fixed points , the equivalencies and the dynamical bifurcations of the universal regular autonomous asynchronous systems .
we use analogies with the dynamical systems theory . .
And you have already written the first three sentences of the full article: we denote by @xmath3 the * binary boole algebra * , endowed with the discrete topology and with the usual laws . let be the boolean function @xmath4 and @xmath5 we define
@xmath6 by @xmath7@xmath8 @xmath9 represents the function resulting from @xmath10 when this one is not computed , in general , on all the coordinates @xmath11 if @xmath12
then @xmath13 is not computed , @xmath14 and if @xmath15 then @xmath13 is computed , @xmath16 let be the sequence @xmath17 the functions @xmath18 are defined iteratively by @xmath19@xmath20 the sequence @xmath21 is called * progressive * if@xmath22 the set of the progressive sequences is denoted by @xmath23 let be @xmath24 when @xmath25 is progressive , each coordinate @xmath26 is computed infinitely many times in the sequence @xmath27 @xmath28 ..
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this is the meaning of the progress property , giving the so called unbounded delay model of computation of the boolean functions .
the * initial value * , denoted by @xmath29 or @xmath30 and the * final value * , denoted by @xmath31 or @xmath32 of the function @xmath33 are defined by@xmath34@xmath35 the function @xmath33 is called ( * pseudo*)*periodical with the period * @xmath36 if \a ) @xmath37 does not exist and \b ) @xmath38 the * characteristic function * @xmath39 of the set @xmath40 is defined in the following way:@xmath41{c}1,\;if\;t\in a\;\\ 0,otherwise \end{array } \right . .\ ] ] we denote by @xmath42 the set of the real sequences @xmath43 which are unbounded from above . the sequences @xmath44 act as time sets . at this level of generality of the exposure
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Suppose that you have an abstract for a scientific paper: a model is presented that seeks to quantitatively explain the stellar abundances of @xmath0-process elements and other elements associated with the @xmath0-process sites .
it is argued that the abundances of all these elements in stars with @xmath1}<-1 $ ] can be explained by the contributions of three sources .
the sources are : the first generations of very massive @xmath2 stars that are formed from big bang debris and are distinct from snii , and two types of snii , the @xmath3 and @xmath4 events , which can occur only at [ fe / h ] @xmath5 .
the @xmath3 events are of high frequency and produce dominantly heavy ( @xmath6 ) @xmath0-elements but no fe ( presumably leaving behind black holes ) .
the @xmath4 events are of low frequency and produce fe and dominantly light ( @xmath7 ) @xmath0-elements ( essentially none above ba ) . by using the observed abundances in two ultra - metal - poor stars and the solar @xmath0-abundances , the initial or prompt inventory of elements produced by the first generations of very massive stars and the yields of @xmath3 and @xmath4 events can be determined .
the abundances of a large number of elements in a star can then be calculated from the model by using only the observed eu and fe abundances . to match the model results and the observational data for stars with
@xmath8}<-1 $ ] requires that the solar @xmath0-abundances for sr , y , zr , and ba must be significantly increased from the standard values .
no such changes appear to be required for all other elements .
if the changes in the solar @xmath0-abundances for sr , y , zr , and ba are not permitted , the model fails at @xmath8}<-1 $ ] but still works at [ fe / h ] @xmath9 for these four elements . by using the corrected solar @xmath0-abundances for these elements
, good agreement is obtained between the model results and data over the range @xmath8}<-1 $ ] .
no evidence of @xmath10-process contributions is found in this region , but all the observational data in this region now show regular....
And you have already written the first three sentences of the full article: we present a phenomenological model that seeks to explain abundances of a large number of elements in ultra - metal - poor ( ump ) stars with [ fe / h ] @xmath9 and extend this model to metal - poor ( mp ) stars with @xmath8}<-1 $ ] . recently
burris et al . ( 2000 ) reported abundances of heavy elements , both above and below ba , in 70 galactic halo stars with a wide range in [ fe / h ] .
this new work and previous observations by e.g. , mcwilliam et al ..
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( 1995 ) and ryan , norris , & beers ( 1996 ) stimulated us to address the problem of chemical evolution in the early galaxy .
recent studies have discussed galactic chemical evolution of h to zn ( timmes , woosley , & weaver 1995 ) and of heavy elements from ba to eu with both @xmath10-process and @xmath0-process contributions ( travaglio et al .
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Suppose that you have an abstract for a scientific paper: we present the first detailed assessment of the large - scale rotation of any galaxy based on full three - dimensional velocity measurements .
we do this for the large magellanic cloud ( lmc ) by combining our hubble space telescope average proper motion ( pm ) measurements for stars in 22 fields , with existing line - of - sight ( los ) velocity measurements for 6790 individual stars .
we interpret these data with a model of circular rotation in a flat disk .
the pm and los data paint a consistent picture of the lmc rotation , and their combination yields several new insights .
the pm data imply a stellar dynamical center that coincides with the hi dynamical center ( but offset from the photometric center ) , and a rotation curve amplitude that is consistent with that inferred from los velocity studies .
this resolves several puzzles posed by existing work .
the implied viewing angles of the lmc disk agree with the range of values found in the literature , but continue to indicate variations with stellar population and/or radius in the disk .
young ( red supergiant ) stars rotate faster than old ( red and asymptotic giant branch ) stars due to asymmetric drift . outside the central region ,
the rotation curve is approximately flat out to the outermost data .
the circular velocity @xmath0 ( with the uncertainty dominated by inclination uncertainties ) is consistent with the baryonic tully - fisher relation , and implies an enclosed mass @xmath1 .
the virial mass is larger , depending of the full extent of the lmc s dark halo .
the tidal radius is @xmath2 ( @xmath3 ) , if the circular velocity stays flat this far out .
combination of the pm and los data yields kinematic distance estimates for the lmc , but these are not yet competitive with other methods . .
And you have already written the first three sentences of the full article: measurements of galaxy rotation curves form the foundation of much of our understanding of galaxy formation , structure , and dynamics ( e.g. , binney & merrifield 1998 ; binney & tremaine 2008 ; mo , van den bosch , & white 2010 ) . the current knowledge of galaxy rotation is based entirely on observations of doppler shifts in radiation from galaxies .
this yields only one coordinate of motion , the los velocity .
if a galaxy rotates , and is not viewed edge - on , it will also rotate in the plane of the sky . until now.
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, the implied pms have generally been undetectable , given the available observational capabilities .
however , the observational capabilities have steadily advanced .
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Suppose that you have an abstract for a scientific paper: our knowledge of planets orbital dynamics , which was based on solar system studies , has been challenged by the diversity of exoplanetary systems . around cool and ultra cool dwarfs
, the influence of tides on the orbital and spin evolution of planets can strongly affect their climate and their capacity to host surface liquid water .
we illustrate the role of tides and dynamics with the extreme case of planets orbiting around brown dwarfs . in multiple planet systems ,
the eccentricity is excited by planet - planet interactions .
planets are therefore heated up from the inside by the tidally - induced friction .
this process can heat a habitable zone planet to such a level that surface liquid water can not exist .
we also talk about the newly discovered potentially habitable earth - sized planet kepler-186f . given the poorly estimated age of the system
, the planet could still be evolving towards synchronization and have a high obliquity or be pseudo - synchronized with a zero obliquity .
these two configurations would have a different effect on the climate of this planet .
planets and satellites : atmospheres , planets and satellites : dynamical evolution and stability , planets and satellites : individual : kepler-186f .
And you have already written the first three sentences of the full article: since 1995 and the discovery of the first exoplanet orbiting a sun - like star @xcite , the number of detected exoplanets has been steadily increasing . with now almost 1500 confirmed exoplanets ( http://exoplanets.org/ ) and around 20 of them good candidates to host surface liquid water ( http://phl.upr.edu/projects/habitable-exoplanets-catalog ) , we enter in an fascinating age . with the improvements made in exoplanet detection , we are able to detect planets less and less massive ( or smaller and smaller ) approaching the mass ( or size ) range of the earth .
we are now also able to probe the habitable zone of stars .
we define here the habitable zone ( hz ) as the region around a star where a planet with the right atmosphere can potentially sustain surface liquid water @xcite ..
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most of the detected hz planets are either too massive ( radial velocity planets ) or too large ( transit planets ) to be categorized unequivocally as terrestrial planets .
for example , kepler-22b , a 2.4 @xmath0 planet could be either a mini - neptune or a super - earth @xcite .
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Suppose that you have an abstract for a scientific paper: we propose and analyze a generalized two dimensional @xmath0 model , whose interaction potential has @xmath1 weighted wells , describing corresponding symmetries of the system . as the lattice spacing vanishes , we derive by @xmath2-convergence the discrete - to - continuum limit of this model . in the energy regime
we deal with , the asymptotic ground states exhibit fractional vortices , connected by string defects .
the @xmath2-limit takes into account both contributions , through a renormalized energy , depending on the configuration of fractional vortices , and a surface energy , proportional to the length of the strings .
our model describes in a simple way several topological singularities arising in physics and materials science . among them ,
disclinations and string defects in liquid crystals , fractional vortices and domain walls in micromagnetics , partial dislocations and stacking faults in crystal plasticity . * keywords : * @xmath0 spin systems , ginzburg - landau , liquid crystals , dislocations , calculus of variations , @xmath2-convergence + * mathematical classification : * 82d30 , 82b20 , 49j45 .
And you have already written the first three sentences of the full article: since the pioneering paper by kosterlitz and thouless @xcite , the @xmath0 model is considered the classical example of discrete spin system exhibiting phase transitions mediated by the formation and the interaction of topological singularities . even at zero temperature
the model presents interesting features : depending on the energy regime , the geometry of the ground states is very rich , going from uniform to disordered states , all the way through isolated vortex singularities and clustered dipoles .
both topology and energy concentration take place at different length scales , thus making the analysis fascinating and popular also in the mathematical community ..
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in this paper we focus on the variational analysis of a two dimensional modified @xmath0 model at zero temperature , describing the formation of fractional vortices and string defects .
our main motivation comes from observing that this kind of singularities characterizes several discrete systems in physics and materials science such as disclinations and string defects in liquid crystals @xcite , fractional vortices and domain walls in micromagnetics @xcite , partial dislocations and stacking faults in crystal plasticity @xcite .
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Suppose that you have an abstract for a scientific paper: leclerc and zelevinsky described quasicommuting families of quantum minors in terms of a certain combinatorial condition , called _ weak separation .
_ they conjectured that all maximal by inclusion weakly separated collections of minors have the same cardinality , and that they can be related to each other by a sequence of mutations . on the other hand
, postnikov studied _ total positivity _ on the grassmannian .
he described a stratification of the totally nonnegative grassmannian into _ positroid strata , _ and constructed their parametrization using _ plabic graphs .
_ in this paper we link the study of weak separation to plabeic graphs .
we extend the notion of weak separation to positroids .
we generalize the conjectures of leclerc and zelevinsky , and related ones of scott , and prove them . we show that the maximal weakly separated collections in a positroid are in bijective correspondence with the plabic graphs .
this correspondence allows us to use the combinatorial techniques of positroids and plabic graphs to prove the ( generalized ) purity and mutation connectedness conjectures . .
And you have already written the first three sentences of the full article: leclerc and zelevinsky @xcite , in their study of quasicommuting families of quantum minors , introduced the following notion of weakly separated sets .
let @xmath0 and @xmath1 be two subsets of @xmath2:=\ { 1,2 , \ldots , n \}$ ] .
leclerc and zelevinsky @xcite , defined @xmath0 and @xmath1 to be _ weakly separated _ if either 1 ..
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@xmath3 and @xmath4 can be partitioned as @xmath5 such that @xmath6 , or 2 .
@xmath7 and @xmath8 can be partitioned as @xmath9 such that @xmath10 , where @xmath11 indicates that every element of @xmath12 is less than every element of @xmath13 .
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Suppose that you have an abstract for a scientific paper: particle number fluctuations and correlations in nucleus - nucleus collisions at sps and rhic energies have been studied within the hadron - string - dynamics ( hsd ) transport approach .
event - by - event fluctuations of pion - to - kaon , proton - to - pion and kaon - to - proton number ratios are calculated for the samples of most central collision events and compared with the available experimental data .
it has been found that the hsd model can qualitatively reproduce the measured excitation function for the @xmath0 ratio fluctuations in central au+au ( or pb+pb ) collisions from low sps up to top rhic energies .
these predictions impose a challenge for future experiments . .
And you have already written the first three sentences of the full article: the measurement of the fluctuations in the kaon to pion ratio by the na49 collaboration was the first event - by - event analysis in nucleus - nucleus collisions @xcite .
it was suggested that this ratio might allow to distinguish events with enhanced strangeness production attributed to the qgp phase @xcite .
nowadays , the excitation function for this observable is available in a wide range of energies : from the na49 collaboration @xcite in pb+pb collisions at the cern sps and from the star collaboration @xcite in au+au collisions at rhic ..
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results from na49 show an enhancement of fluctuations in the kaon to pion multiplicity ratio for low energies which may be a signal of a deconfinement phase transition . on the other hand
there is no such an enhancement for the proton to pion ratio fluctuations .
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Suppose that you have an abstract for a scientific paper: it is well known that loss of information about a system , for some observer , leads to an increase in entropy as perceived by this observer .
we use this to propose an alternative approach to decoherence in quantum field theory in which the machinery of renormalisation can systematically be implemented : neglecting observationally inaccessible correlators will give rise to an increase in entropy of the system . as an example we calculate the entropy of a general gaussian state and , assuming the observer s ability to probe this information experimentally , we also calculate the correction to the gaussian entropy for two specific non - gaussian states . .
And you have already written the first three sentences of the full article: the most natural way of defining the entropy of a quantum system is to use the von neumann entropy : @xmath0\ , , \label{entropy : vn}\ ] ] where @xmath1 denotes the density operator which in the schrdinger picture satisfies the von neumann equation : @xmath2 \ , , \label{density op : eom}\ ] ] where @xmath3 is the hamiltonian .
since quantum mechanics and quantum field theory are unitary theories , the von neumann entropy is conserved , albeit in general not zero .
the decoherence program @xcite usually assumes the existence of some environment that is barely observable to some observer ..
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this allows us to construct a reduced density operator @xmath4 characterising the system s , which is obtained by tracing over the unobservable environmental degrees of freedom e : @xmath5 $ ] .
this is a non - unitary process which consequently generates entropy .
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Suppose that you have an abstract for a scientific paper: we probe the rheology of weakly vibrated granular flows as function of flow rate , vibration strength and pressure by performing experiments in a vertically vibrated split - bottom shear cell . for slow flows ,
we establish the existence of a novel vibration dominated granular flow regime , where the driving stresses smoothly vanish as the driving rate is diminished .
we distinguish three qualitatively different vibration dominated rheologies , most strikingly a regime where the shear stresses no longer are proportional to the pressure .
granular media are collections of macroscopic , athermal grains which interact through dissipative , frictional contact forces . in the presence of gravity and in the absence of additional external forces , they jam in metastable configurations ; however , external forcing can easily lead to yielding and flow @xcite .
the best known scenario that leads to granular flow is by exerting shear stresses that exceed the yield stress , as when tilting a quiescent layer of sand sufficiently far away from the horizontal @xcite . to understand such dense granular flows
, it is becoming increasingly clear that both stress and mechanical agitations play a crucial role .
indeed , a given stress can give rise to a wide range of flow rates depending on the magnitude of these agitations @xcite .
moreover , agitations make granular media lose their rigidity , although in the absence of shear stresses this does not need to cause flow @xcite .
we note here that the idea that both the stress and the amount of agitations determine the flow rate lies at the basis of numerous models for slowly flowing disordered materials @xcite .
is used to probe the rheology of agitated granular media .
the crucial experimental parameters are the filling height , @xmath0 , vibration amplitude , @xmath1 , the torque , @xmath2 , and the rotation rate , @xmath3.,width=188 ] in a granular context , such agitations may be provided by external vibrations . in a classic experiment ,
the....
And you have already written the first three sentences of the full article: in this section we briefly introduce the main parts of our experimental setup ( for details , see appendix [ app : setup ] ) , discuss our measurement protocols , and show how we ensure that we measure steady values for the rheology .
we probe the rheology of weakly vibrated granular flows in a modified split - bottom cell , as shown in fig . 1 .
the acrylic container has an inner radius of 7 cm . we mount a hollow smooth cylinder of 6 mm height and 4 cm radius on the bottom of the container ..
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the rotating disk ( radius @xmath5 of 4 cm and thickness 5 mm ) that drives the granular flow is mounted just above the cylinder .
the gap between the container and the disk is about 0.3 mm so no particles can get underneath the disk . to ensure a no - slip boundary condition ,
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Suppose that you have an abstract for a scientific paper: networks of living neurons exhibit an avalanche mode of activity , experimentally found in organotypic cultures .
moreover , experimental studies of morphology indicates that neurons develop a network of small - world - like connections , with the possibility of very high connectivity degree .
here we study a recent model based on self - organized criticality , which consists in an electrical network with threshold firing and activity - dependent synapse strengths .
we study the model on a scale - free network , the apollonian network , which presents many features of neuronal systems .
the system exhibits a power law distributed avalanche activity .
the analysis of the power spectra of the electrical signal reproduces very robustly the power law behaviour with the exponent 0.8 , experimentally measured in electroencephalograms ( eeg ) spectra .
the exponents are found quite stable with respect to initial configurations and strength of plastic remodelling , indicating that universality holds for a wide class of brain models .
= + 1truecm .
And you have already written the first three sentences of the full article: neuronal networks exhibit diverse patters of activity , including oscillations , synchronization and waves . during neuronal activity ,
each neuron can receive inputs by thousands of other neurons and , when it reaches a threshold , redistributes this integrated activity back to the neuronal network .
recently a neuronal activity based on avalanches has been observed in organotypic cultures from coronal slices of rat cortex @xcite where neuronal avalanches are stable for many hours @xcite ..
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more precisely , recording spontaneous local potentials continuously by a multielectrode array , has shown that activity initiated at one electrode might spread to other electrodes not necessarily contiguous , as in a wave - like propagation .
cortical slices are then found to exhibit a new form of activity , producing several avalanches per hour of different duration , in which non - synchronous activity is spread over space and time . by analysing the size and duration of neuronal avalanches ,
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Suppose that you have an abstract for a scientific paper: we obtain explicit formulas for the number of non - isomorphic elliptic curves with a given group structure ( considered as an abstract abelian group ) .
moreover , we give explicit formulas for the number of distinct group structures of all elliptic curves over a finite field .
we use these formulas to derive some asymptotic estimates and tight upper and lower bounds for various counting functions related to classification of elliptic curves accordingly to their group structure . finally , we present results of some numerical tests which exhibit several interesting phenomena in the distribution of group structures .
we pose getting an explanation to these as an open problem . .
And you have already written the first three sentences of the full article: let @xmath0 be the finite field of characteristic @xmath1 with @xmath2 elements .
an elliptic curve @xmath3 over a finite field @xmath0 is given by the _ weierstrass equation _
@xmath4 where the coefficients @xmath5 are in @xmath0 ; see @xcite for a general background and see @xcite for cryptographic interests on elliptic curves . as usual.
Please generate the next two sentences of the article
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, let @xmath6 be the set of @xmath0-rational points on elliptic curve @xmath3 including the point at infinity denoted by @xmath7 .
it is known , see @xcite , that @xmath6 is a finite _ abelian _ group with the neutral element @xmath7 and the cardinality of this group satisfies the _ hasse - weil _ bound as @xmath8 it is also known , see @xcite , that the group structure of @xmath6 is expressed by the group isomorphism @xmath9 where unique integers @xmath10 satisfy @xmath11 for the prime power @xmath12 and positive integers @xmath13 ,
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11,197 |
Suppose that you have an abstract for a scientific paper: we propose a mean field ( mf ) theory for a homogeneously driven granular gas of inelastic particles with coulomb friction .
the model contains three parameters , a normal restitution coefficient @xmath0 , a maximum tangential restitution coefficient @xmath1 , and a coulomb friction coefficient @xmath2 .
the parameters can be tuned to explore a wide range of physical situations . in particular , the model contains the frequently used @xmath3 limit as a special case . the mf theory is compared with the numerical simulations of a randomly driven monolayer of spheres for a wide range of parameter values . if the system is far away from the clustering instability ( @xmath4 ) , we obtain a good agreement between mean field and simulations for @xmath5 and @xmath6 , but for much smaller values of @xmath0 the agreement is less good .
we discuss the reasons of this discrepancy and possible refinements of our computational scheme .
kinetic and transport theory of gases , computational methods in fluid dynamics pacs : 47.50+d , 51.10.+y , 47.11.+j .
And you have already written the first three sentences of the full article: -0.5 cm granular gases @xcite are usually described as collections of macroscopic particles with rough surfaces and dissipative interactions . in order to study them , kinetic theories @xcite and numerical simulations @xcite
were applied for special boundary conditions .
the dynamics of the system is assumed to be dominated by two - particle collisions , modeled by their asymptotic states : a collision is characterized by the velocities before and after the contact , and the contact is assumed to be instantaneous . in the simplest model.
Please generate the next two sentences of the article
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, one describes inelastic collisions by normal restitution @xmath0 only . however , surface roughness is important @xcite , since it allows for an exchange of translational and rotational energy .
here we briefly sketch a study of a model where a coulomb friction law with coefficient @xmath2 and a tangential restitution coefficient @xmath7 account for tangential inelasticity and friction @xcite .
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11,198 |
Suppose that you have an abstract for a scientific paper: the exact nature of weak absorbers ( those with @xmath0 ) is a matter of debate , but most are likely related to areas of local star formation or supernovae activity outside of giant galaxies . using 18 qso spectra obtained with the ultra - violet echelle spectrograph ( uves ) on the very large telescope ( vlt ) ,
we have conducted a survey for weak absorbers at @xmath1 .
we searched a redshift path length of @xmath2 , eliminating regions badly contaminated by atmospheric absorption so that the survey is close to 100% complete to @xmath3 .
we found a total of 9 weak absorbers , yielding a number density of absorbers of @xmath4 for @xmath5 .
@xcite found @xmath6 at @xmath7 and @xcite found @xmath8 at @xmath9 .
therefore , the population of weak absorbers appears to peak at @xmath10 .
we explore the expected evolution of the absorber population subject to a changing extragalactic background radiation ( ebr ) from @xmath11 to @xmath12 ( the median redshift of our survey ) , and find that the result is higher than the observed value .
we point out that the peak epoch for weak absorption at @xmath13 may coincide with the peak epoch of global star formation in the dwarf galaxy environment . .
And you have already written the first three sentences of the full article: quasar absorption line systems ( qals ) are unique and powerful tools for studying the chemical content , kinematics , ionization state , and overall structure of galaxies as well as of the intergalactic medium over @xmath14 .
absorption is an important feature in many qals , because it relates to metal forming processes .
the mg0.1emii @xmath15 doublet is a strong transition and is easily detected in low ionization qals , making it an extremely useful tool for probing galaxies and their environments and for studying the structure of the intergalactic medium ..
Please generate the next two sentences of the article
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weak absorbers are defined to be those absorbers with @xmath0 , and at least some of them represent a unique population(s ) of absorbers that appears to be much different from stronger absorbers @xcite . unlike strong absorbers , which are typically associated with luminous galaxies ( within @xmath16 kpc ) @xcite ,
weak absorbers at @xmath9 are not typically found within @xmath17 kpc of such a galaxy ( * ? ? ?
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11,199 |
Suppose that you have an abstract for a scientific paper: the prediction of wind speed is very important when dealing with the production of energy through wind turbines . in this paper , we show a new nonparametric model , based on semi - markov chains , to predict wind speed .
particularly we use an indexed semi - markov model that has been shown to be able to reproduce accurately the statistical behavior of wind speed .
the model is used to forecast , one step ahead , wind speed . in order to check the validity of the model
we show , as indicator of goodness , the root mean square error and mean absolute error between real data and predicted ones . we also compare our forecasting results with those of a persistence model . at last ,
we show an application of the model to predict financial indicators like the internal rate of return , duration and convexity . .
And you have already written the first three sentences of the full article: the variations of wind speed , in a certain site , are strictly related to the economic aspects of a wind farm , such as maintenance operations , especially in the off shore farms , pitch angle control on new wind turbines and evaluation of a new site .
many scholars have proposed new models that can allow the prediction of wind speed , minutes , hours or days ahead .
many of these models are based on neural networks @xcite , autoregressive models @xcite , markov chains @xcite , hybrid models where the previous mentioned models are combined @xcite , @xcite and other models @xcite ..
Please generate the next two sentences of the article
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often , these models are either focused on specific time scale forecasting , or synthetic time series generation .
the approach we propose here is based on indexed semi - markov chain ( ismc ) model that was advanced by the same authors in @xcite and applied to the generation of synthetic wind speed time series . in @xcite
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