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4,200 | Suppose that you have an abstract for a scientific paper: this article is a brief guide to the field of algorithmic information theory ( ait ) , its underlying philosophy , and the most important concepts .
ait arises by mixing information theory and computation theory to obtain an objective and absolute notion of information in an individual object , and in so doing gives rise to an objective and robust notion of randomness of individual objects .
this is in contrast to classical information theory that is based on random variables and communication , and has no bearing on information and randomness of individual objects .
after a brief overview , the major subfields , applications , history , and a map of the field are presented . .
And you have already written the first three sentences of the full article: algorithmic information theory ( ait ) is a the of individual objects , using , and concerns itself with the relationship between computation , information , and randomness .
the information content or complexity of an object can be measured by the length of its shortest description .
for instance the string `` 0101010101010101010101010101010101010101010101010101010101010101 '' has the short description `` 32 repetitions of 01'' , while `` 1100100001100001110111101110110011111010010000100101011110010110 '' presumable has no simple description other than writing down the string itself ..
Please generate the next two sentences of the article | more formally , the ( ac ) of a string @xmath0 is defined as the length of the shortest program that computes or outputs @xmath0 , where the program is run on some fixed universal computer .
a closely related notion is the probability that a universal computer outputs some string @xmath0 when fed with a program chosen at random . |
4,201 | Suppose that you have an abstract for a scientific paper: the hydrodynamic escape problem ( hep ) , which is characterized by a free boundary value problem of euler equation with gravity and heat , is crucial for investigating the evolution of planetary atmospheres . in this paper , the global existence of transonic solutions to the hep is established using the generalized glimm method . the new version of riemann and boundary - riemann solvers ,
are provided as building blocks of the generalized glimm method by inventing the contraction matrices for the homogeneous riemann ( or boundary - riemann ) solutions .
the extended glimm - goodman wave interaction estimates are investigated for obtaining a stable scheme and positive gas velocity , which matches the physical observation .
the limit of approximation solutions serves as an entropy solution of bounded variations .
moreover , the range of the hydrodynamical region is also obtained .
+ + msc : 35l50 , 35l60 , 35l65 , 35l67 , 76n10 , 85a20 , 85a30 + + keywords : hydrodynamic escape problem ; nonlinear hyperbolic systems of balance laws ; generalized riemann and boundary - riemann problems ; generalized glimm scheme ; hydrodynamic region . .
And you have already written the first three sentences of the full article: spacecraft exploration of the planets in our solar system and the discovery of exoplanets has attracted considerable attention in the atmospheric escape from planetary objects @xcite .
the cassini spacecraft currently improves our understanding of the atmospheric escape from titan @xcite .
the maven mission circuits around mars for studying its atmospheric composition @xcite . in july 2015 , the new horizons ( nh ) spacecraft completed its flyby of pluto and discovered flowing ice and an extended haze on the planet ..
Please generate the next two sentences of the article | pluto already exhibits a planetary geology that comprises flowing ices , exotic surface chemistry , mountain ranges , and vast haze . analyzing pluto
s atmosphere reveals that pluto s surface has a reddish hue , a simple hydrocarbon in its atmosphere , and the temperature for hazes to form at altitudes higher than 30 kilometers above pluto s surface . |
4,202 | Suppose that you have an abstract for a scientific paper: scientific studies often require the precise calculation of derivatives . in many cases
an analytical calculation is not feasible and one resorts to evaluating derivatives numerically
. these are error - prone , especially for higher - order derivatives . a technique based on algorithmic differentiation
is presented which allows for a precise calculation of higher - order derivatives .
the method can be widely applied even for the case of only numerically solvable , implicit dependencies which totally hamper a semi - analytical calculation of the derivatives . as a demonstration
the method is applied to a quantum field theoretical physical model .
the results are compared with standard numerical derivative methods .
algorithmic differentiation , numerical differentiation , taylor expansion , quantum chromodynamics 02.60.gf , 02.70.bf , 12.38.aw , 11.30.rd .
And you have already written the first three sentences of the full article: in many scientific studies the knowledge of derivatives of a given quantity is of particular importance .
for example in theoretical physics , especially in thermodynamics , many quantities of interest require the calculation of derivatives of an underlying thermodynamic potential with respect to some external parameters such as temperature , volume , or chemical potentials .
in many cases the thermodynamic potentials can only be evaluated numerically and one is forced to employ numerical differentiation techniques which are error - prone as any numerical methods ..
Please generate the next two sentences of the article | furthermore , the thermodynamic potential has to be evaluated at the physical point defined by minimizing the thermodynamic potential with respect to some condensates yielding the equations of motion ( eom ) .
generally , these equations can be solved only numerically and thus introduce additional implicit dependencies which makes the derivative calculations even more complicated . even in cases where |
4,203 | Suppose that you have an abstract for a scientific paper: young pulsars produce relativistic winds which interact with matter ejected during the supernova explosion and the surrounding interstellar gas .
particles are accelerated to very high energies somewhere in the pulsar winds or at the shocks produced in collisions of the winds with the surrounding medium . as a result of interactions of relativistic leptons with the magnetic field and low energy radiation ( of synchrotron origin , thermal , or microwave background )
, the non - thermal radiation is produced with the lowest possible energies up to @xmath0100 tev .
the high energy ( tev ) @xmath1-ray emission has been originally observed from the crab nebula and recently from several other objects .
recent observations by the hess cherenkov telescopes allow to study for the first time morphology of the sources of high energy emission , showing unexpected spectral features .
they might be also interpreted as due to acceleration of hadrons .
however , theory of particle acceleration in the pwne and models for production of radiation are still at their early stage of development since it becomes clear that realistic modeling of these objects should include their time evolution and three - dimensional geometry . in this paper
we concentrate on the attempts to create a model for the high energy processes inside the pwne which includes existence not only relativistic leptons but also hadrons inside the nebula .
such model should also take into account evolution of the nebula in time .
possible high energy expectations based on such a model are discussed in the context of new observations .
example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave .4 setgray fill grestore stroke grestore .
And you have already written the first three sentences of the full article: the non - thermal nebulae around young energetic pulsars ( pulsar wind nebulae - pwne ) have been suspected to accelerate leptons to sufficiently large energies allowing production of tev @xmath1-rays ( e.g. gould 1965 , rieke & weekes 1969 , grindlay & hoffman 1971 , stepanian 1980 ) . in fact , the nebula around the crab pulsar was originally reported by the whipple group as a first tev @xmath1-ray source ( weekes et al .
later , detections of tev @xmath1-rays from nebulae around other pulsars have also been claimed ( e.g. around psr 1706 - 44 - kifune et al .
1995 , chadwick et al . 1998 , vela pulsar - yoshikoshi et al ..
Please generate the next two sentences of the article | 1997 , or psr 1509 - 58 ( msh 15 - 52 ) - sako et al .
2000 ) , but some of the reported emission features have not been confirmed by recent more sensitive observations ( see e.g. the results of hess collab . concerning psr 1706 - 44 - aharonian et al . 2005a , or vela pulsar - aharonian et al . |
4,204 | Suppose that you have an abstract for a scientific paper: multivariate functions are typically governed by anisotropic features such as edges in images or shock fronts in solutions of transport - dominated equations .
one major goal both for the purpose of compression as well as for an efficient analysis is the provision of optimally sparse approximations of such functions .
recently , cartoon - like images were introduced in 2d and 3d as a suitable model class , and approximation properties were measured by considering the decay rate of the @xmath0 error of the best @xmath1-term approximation .
shearlet systems are to date the only representation system , which provide optimally sparse approximations of this model class in 2d as well as 3d .
even more , in contrast to all other directional representation systems , a theory for compactly supported shearlet frames was derived which moreover also satisfy this optimality benchmark .
this chapter shall serve as an introduction to and a survey about sparse approximations of cartoon - like images by band - limited and also compactly supported shearlet frames as well as a reference for the state - of - the - art of this research field . .
And you have already written the first three sentences of the full article: scientists face a rapidly growing deluge of data , which requires highly sophisticated methodologies for analysis and compression . simultaneously , the complexity of the data is increasing , evidenced in particular by the observation that data becomes increasingly high - dimensional .
one of the most prominent features of data are singularities which is justified , for instance , by the observation from computer visionists that the human eye is most sensitive to smooth geometric areas divided by sharp edges .
intriguingly , already the step from univariate to multivariate data causes a significant change in the behavior of singularities . whereas one - dimensional ( 1d ) functions can only exhibit point singularities , singularities of two - dimensional ( 2d ) functions.
Please generate the next two sentences of the article | can already be of both point as well as curvilinear type .
thus , in contrast to _ isotropic _ features point singularities , suddenly _ anisotropic _ features |
4,205 | Suppose that you have an abstract for a scientific paper: we report measurements of the time - dependent phases of the leak and retrieved pulses obtained in eit storage experiments with metastable helium vapor at room temperature .
in particular , we investigate the influence of the optical detuning at two - photon resonance , and provide numerical simulations of the full dynamical maxwell - bloch equations , which allow us to account for the experimental results . .
And you have already written the first three sentences of the full article: because they do not interact with each other and can be guided via optical fibers over long distances with relatively low losses , photons appear as ideal information carriers and are therefore put forward as the flying qubits in most of quantum communication protocols .
the design of memories able to reliably store and retrieve photonic states is , however , still an open problem . the most commonly studied protocol , considered to implement such a quantum memory , is electromagnetically induced transparency ( eit ) @xcite .
this protocol was implemented in various systems such as cold atoms , gas cells , or doped crystals @xcite ..
Please generate the next two sentences of the article | although the doppler broadening might seem to lead to strong limitations , eit - based light storage in warm alkali vapors gives good results and is still a subject of active investigation @xcite . in the last years
, some experiments were also performed in a raman configuration , using pulses which are highly detuned from the optical resonances in gas cells @xcite . |
4,206 | Suppose that you have an abstract for a scientific paper: cyclic codes have efficient encoding and decoding algorithms .
the decoding error probability and the undetected error probability are usually bounded by or given from the weight distributions of the codes .
most researches are about the determination of the weight distributions of cyclic codes with few nonzeros , by using quadratic form and exponential sum but limited to low moments . in this paper , we focus on the application of higher moments of the exponential sum to determine the weight distributions of a class of ternary cyclic codes with three nonzeros , combining with not only quadratic form but also macwilliams identities .
another application of this paper is to emphasize the computer algebra system magma for the investigation of the higher moments . in the end ,
the result is verified by one example using matlab .
submitted paper cyclic code , exponential sum , macwilliams identities , quadratic form , weight distribution .
And you have already written the first three sentences of the full article: cyclic codes have a lot of applications in communication system , storage system and computers . the decoding error probability and the undetected error probability
are closely related with the weight distributions .
for example , permutation decoding , majority decoding , locator decoding , decoding from the covering polynomials and so on @xcite . in general.
Please generate the next two sentences of the article | the weight distributions are complicated @xcite and difficult to be determined .
in fact , as shown in @xcite and @xcite , the problem of computing weight distribution of a cyclic code is connected to the evaluation of certain exponential sums , which are generally hard to be determined explicitly . for more researches , |
4,207 | Suppose that you have an abstract for a scientific paper: exploiting a 3 + 1 analysis of the mars - simon tensor , conditions on a vacuum initial data set ensuring that its development is isometric to a subset of the kerr spacetime are found .
these conditions are expressed in terms of the vanishing of a positive scalar function defined on the initial data hypersurface .
applications of this result are discussed . .
And you have already written the first three sentences of the full article: the kerr spacetime is one of the most important exact solutions to the einstein vacuum equations .
its relevance stems from the uniqueness theorems for black holes which state that under rather general conditions the kerr spacetime is the only asymptotically flat , stationary , vacuum black hole solution see e.g. the introduction of @xcite for a critical review of the issue of black hole uniqueness and the involved assumptions .
although , the kerr spacetime is very well understood from a spacetime perspective , the same can not be said if one adopts a 3 + 1 point of view which would be the case if one tries to numerically calculate the spacetime from some cauchy initial data ..
Please generate the next two sentences of the article | as soon as one moves away from a 3 + 1 gauge which is adapted to the stationary and axial symmetries which can occur in some applications , in particular in numerical ones an analysis of the kerr spacetime and initial data sets thereof becomes very complicated .
the explicit nature of the kerr solution makes it tempting to perform detailed calculations in order to , say , verify a particular property of the spacetime . |
4,208 | Suppose that you have an abstract for a scientific paper: the strong coulomb interaction between massless dirac fermions can drive a semimetal - insulator transition in single - layer graphene by dynamically generating an excitonic fermion gap .
there is a critical interaction strength @xmath0 that separates the semimetal phase from the insulator phase .
we calculate the specific heat and susceptibility of the system and show that they exhibit distinct behaviors in the semimetal and insulator phases .
massless dirac fermion , semimetal - insulator transition , non - fermi liquid behavior 73.43.nq , 71.10.hf , 71.30.+h .
And you have already written the first three sentences of the full article: the low - energy properties of graphene have been widely investigated theoretically and experimentally in recent years @xcite .
it is well - known that the low - lying elementary excitations of graphene are massless dirac fermions , which have linear dispersion and display quite different behaviors from ordinary electrons with parabolic dispersion . at half - filling state ,
the density of states of massless dirac fermions vanishes linearly with energy @xmath1 near the fermi level . due to this fact.
Please generate the next two sentences of the article | , there is essentially no screening on the coulomb interaction between dirac fermions .
the unscreened , long - range coulomb interaction was argued @xcite to be responsible for a plenty of unusual physical properties , including the logarithmic velocity renormalization @xcite , the logarithmic specific heat correction @xcite , the presence of quantum critical point @xcite , and the marginal fermi liquid quasiparticle lifetime @xcite . |
4,209 | Suppose that you have an abstract for a scientific paper: we propose a fast algorithm for computing the expected tranche loss in the gaussian factor model with arbitrary accuracy using hermite expansions .
no assumptions about homogeneity of the portfolio are made .
it is intended as an alternative to the much slower fourier transform based methods @xcite . .
And you have already written the first three sentences of the full article: let us consider a portfolio of @xmath0 loans .
let the notional of loan @xmath1 be equal to the fraction @xmath2 of the notional of the whole portfolio .
this means that if loan @xmath1 defaults and the entire notional of the loan is lost the portfolio loses fraction @xmath2 or @xmath3 of its value . in practice.
Please generate the next two sentences of the article | when a loan @xmath1 defaults a fraction @xmath4 of its notional will be recovered by the creditors . thus the actual loss given default ( lgd ) of loan @xmath1 is @xmath5 fraction or @xmath6 of the notional of the entire portfolio .
we now describe the gaussian m - factor model of portfolio losses from default . |
4,210 | Suppose that you have an abstract for a scientific paper: we demonstrate a significant ( @xmath0 ) correlation between the mean color of _ metal - poor _ globular cluster ( gc ) systems and parent galaxy luminosity .
a bayesian markov chain monte carlo method is introduced to find the mean color , and is easily generalizable to quantify multimodality in other astronomical datasets .
we derive a gc color galaxy luminosity relation of the form @xmath1 . when combined with evidence against a _ single _ primordial gc metallicity
galaxy luminosity relation for protogalactic fragments , the existence of such a correlation is evidence against both accretion and major merger scenarios as an explanation of the entire metal - poor gc systems of luminous galaxies .
however , our relation arises naturally in an _ in situ _ picture of gc formation , and is consistent with the truncation of metal - poor gc formation by reionization .
a further implication is that the ages of metal - poor gcs in dwarf galaxies constrain the main epoch of galaxy formation in hierarchical models .
if the ages of old metal - poor gcs in local group dwarfs ( @xmath2 gyr ) are typical of those in dwarfs elsewhere , then the bulk of galaxy assembly ( at least in clusters and groups ) must have occurred at @xmath3 , contrary to the predictions of some structure formation models . .
And you have already written the first three sentences of the full article: a key development in the study of globular clusters ( gcs ) in external galaxies has been the discovery that most large galaxies have bimodal gc color distributions ( e.g. , zepf & ashman 1993 ; forbes , brodie & grillmair 1997 ; gebhardt & kissler - patig 1999 ; kundu & whitmore 2001a ; larsen 2001 ) .
these are usually described as blue ( metal - poor ) and red ( metal - rich ) gc subpopulations , although additional substructure may be present .
the red gc system properties appear to be intimately tied to those of their parent galaxy , suggesting that the red gcs formed along with the bulk of the galaxy field stars ( forbes 1997 ; forbes & forte 2001 ; larsen 2001 ) . in both spirals and ellipticals.
Please generate the next two sentences of the article | , they are thought to be associated with the bulge / spheroid component ( forbes , brodie & larsen 2001 ) .
the blue gcs are among the oldest and most metal - poor stellar systems observable . |
4,211 | Suppose that you have an abstract for a scientific paper: in order to double the positron injection rate into the kekb ring , a two - bunch acceleration scheme has been studied at the linac , in which bunches separated by 96 ns are accelerated in 50 hz . in this scheme stabilization of the energy and orbit of each bunch
is indispensable .
thus , the beam energy and orbit feedback systems have been upgraded .
since beam characteristics are acquired through beam - position monitors ( bpm ) , their read - out system was improved to meet two - bunch requirements . combined waveforms from bpm s
were adjusted with delay cables avoiding overlaps so as to enable the simultaneous measurements of the beam positions of two bunches .
the beam energies of two bunches were balanced by tuning the rf pulse timings , and the average energy was stabilized by adjusting the accelerating rf phases .
the average beam orbits were also stabilized .
slow feedback systems at the injector section for charge and bunching stabilities are being planned as well .
these systems were successfully used in the test beams and will be employed during routine operation . .
And you have already written the first three sentences of the full article: the electron / positron linac at kek injects 8-gev electron and 3.5-gev positron beams into kekb rings , where the cp - violation study is carried out . since the efficiency of the experiment
can be increased by shortening the injection time , several mechanisms have been introduced to accomplish this@xcite .
especially , much effort has been made to improve the positron injection time , since it is longer compared with that of electrons@xcite ..
Please generate the next two sentences of the article | one of such effort is a two - bunch acceleration plan , which has been studied and applied@xcite . in this scheme
two bunches of positrons are accelerated in one rf pulse , which is 50 hz ; they may double the injection rate . |
4,212 | Suppose that you have an abstract for a scientific paper: in this thesis , we obtain the formula for the kac determinant of the algebra arising from the level @xmath0 representation of the ding - iohara - miki algebra .
this formula can be proved by decomposing the level @xmath0 representation into the deformed @xmath1-algebra part and the @xmath2 boson part , and using the screening currents of the deformed @xmath1-algebra .
it is also discovered that singular vectors obtained by its screening currents correspond to the generalized macdonald functions .
moreover , we investigate the @xmath3 limit of five - dimensional agt correspondence . in this limit ,
the simplest 5d agt conjecture is proved , that is , the inner product of the whittaker vector of the deformed virasoro algebra coincides with the partition function of the 5d pure gauge theory .
furthermore , the r - matrix of the ding - iohara - miki algebra is explicitly calculated , and its general expression in terms of the generalized macdonald functions is conjectured .
@xmath4 + phd thesis submitted to nagoya university + graduate school of mathematics + march 2017 .
And you have already written the first three sentences of the full article: the jack symmetric polynomials @xcite are a system of orthogonal polynomials expressing the excited states of an integrable one - dimensional quantum many - body system with the trigonometric type potential called the calogero - sutherland model @xcite .
to be precise , the jack polynomials are eigenfunctions of a hamiltonian @xmath5 which is obtained by a certain transformation of the calogero - sutherland hamiltonian . here
@xmath6 is a parameter appearing in the calogero - sutherland model ..
Please generate the next two sentences of the article | the excited states can be constructed from the jack polynomials . ]
these are one - parameter deformations of the schur symmetric polynomials . in general , being integrable means that the model has sufficiently many conserved quantities , and that system can be analytically solved . like the calogero - sutherland model , many of the integrable systems are not physical models of particles existing in the real world . however , the mathematical structure of the integrable models , e.g. , excellent solvability , can be used to advantage in many fields of mathematics . let us consider symmetric functions which are defined as a projective limit of symmetric polynomials with finite variables ( * ? ? ? |
4,213 | Suppose that you have an abstract for a scientific paper: we present here initial results on the x ray cluster luminosity function ( xclf ) from the bright sharc sample of distant x ray clusters of galaxies .
this sample is 97% complete in its optical identifications and contains @xmath0 x ray luminous clusters in the redshift range @xmath1 ( median @xmath2 ) and @xmath3 [ 0.52.0 kev ] .
we present a preliminary selection function for the bright sharc based on monte carlo simulations . using this selection function ,
we have computed the bright sharc xclf and find it to be fully consistent with a non evolving xclf to @xmath4 and @xmath5 . at @xmath6
, we find evidence for a deficit of clusters compared to that expected from a non evolving xclf .
we detect only one such cluster in the redshift range @xmath7 when we would expect @xmath8 clusters based on the local xclf of de grandi et al .
( 1999 ) .
the statistical significance of this deficit is @xmath9 . to increase the statistical significance of this possible deficit ,
we have combined the bright sharc and the @xmath10 survey of vikhlinin et al ( 1998a ) .
this joint survey covers @xmath11 and contains only one confirmed @xmath12 , @xmath6 cluster , while we would expect @xmath13 such clusters based on the local xclf ( de grandi et al .
1999 ) .
the statistical significance of the deficit in this joint survey increases to 99.5% .
these results remain preliminary because of incompletenesses in the optical follow up and uncertainties in the local xclf . .
And you have already written the first three sentences of the full article: the observed evolution of the space density of clusters of galaxies provides a powerful constraint on the underlying cosmological model .
many authors have demonstrated both analytically and numerically that the expected abundance of clusters , as a function of cosmic epoch , is a sensitive test of the mean mass density of the universe ( @xmath14 ) and the type of dark matter ( press & schechter 1974 ; lacey & cole 1993 , 1994 ; oukbir & blanchard 1992 , 1997 ; henry 1997 ; eke et al .
1996 , 1998 ; viana & liddle 1996 , 1999 ; bryan & norman 1998 ; reichart et al . 1999 ; borgani et al ..
Please generate the next two sentences of the article | 1999 ) .
measurements of the evolution of the cluster abundance have made significant progress over the past decade . |
4,214 | Suppose that you have an abstract for a scientific paper: the author has recently examined the departmental web pages of the ` top 50 ' physics research universities , as ranked by the national research council ( nrc ) @xcite .
most of the departmental web pages contained biographical data ( ie ; year and institute of phd , etc ) of their faculty members .
of the approximately 1750 faculty members at the ` top 50 ' universities that were examined , approximately 100 were female , and around 1425 had available biographical data .
based on this data , the * predicted * fractions of female faculty members at the ` top 50 ' universities are @xmath0,@xmath1 , and @xmath2 at the assistant , associate , and full faculty levels , respectively . the * observed * fractions are @xmath3 , @xmath4 , @xmath5 , respectively . the overall observed number of women faculty is about 15% less than expected , and the depletion is statistically significant .
unfortunately , the study finds that the `` leaky pipeline '' is found to be alive and well for women in academic physics above the postdoctoral level , at all stages of the faculty career ladder .
this result is stark contrast with the conclusion of the american institute of physics ( aip ) 2005 report on women in physics and astronomy ; the aip report concludes that women are actually * more * likely to be hired at the faculty level than their male peers . in this paper
, we will discuss the two key flaws in the aip analysis that led to their faulty conclusion , then describe in detail the analysis performed by the author that corrects these flaws to get an accurate estimate of the ` leakiness ' of the academic pipeline for women physicists past the postdoctoral level .
_ to be submitted to the american journal of physics _
many studies have documented the `` leaky pipeline '' phenomenon for women in the academic hard sciences ( see , for instance , references @xcite and @xcite ) . a recent report that caught the author s interest was the american institute of physics 2005 report on women in....
And you have already written the first three sentences of the full article: this study finds the leaky pipeline phenomenon exists for women past the postdoctoral level at a level of around 15% .
some may wonder if this is a big enough leak to be a problem . in human terms , however , a 15% leak means that we are missing one out of six women who , in an equitable society , would have been physics faculty members .
there are so few women at the faculty level in physics , that losing one out of every six is in fact a serious concern ..
Please generate the next two sentences of the article | especially if we think about what it must take to convince someone to leave a field when , by that point in their careers , they have committed their working lives to physics , and have gone through at least a decade of higher education to get there .
not all women who become physics faculty members have experienced gender discrimination during their careers . however , many do , and it is unfortunate that the combination of gender discrimination and a ` glass ceiling ' phenomenon in the field is preventing more women from becoming physics faculty members . |
4,215 | Suppose that you have an abstract for a scientific paper: this study propose a continuous pathfinding system based on coupled oscillator systems .
we consider acyclic graphs whose vertices are connected by unidirectional edges .
the proposed model autonomously finds a path connecting two specified vertices , and the path is represented by phase - synchronized oscillatory solutions . to develop a system capable of self - recovery ,
that is , a system with the ability to find a path when one of the connections in the existing path is suddenly removed , we implemented three - state boolean - like regulatory rules for interaction functions . we also demonstrate that appropriate installation of inhibitory interaction improves the finding time . .
And you have already written the first three sentences of the full article: in biological systems , a large number of elements , such as cells and organs , interact with each other and adapt system - wide behavior spontaneously in response to changes of environment and of physical constraints .
such spontaneous and adaptive dynamics have been studied in the framework of collective dynamics @xcite . to clarify the mechanism of adaptability , however , we need to investigate how the dynamics of interactions between elements should depend on the global behavior to establish adaptability .
collective dynamics has been studied as a distributed system to investigate how global structures emerge from the interaction of elements ..
Please generate the next two sentences of the article | many types of distributed systems have been modeled by using differential equations , and the system behaviors have been described by appropriate basin switching between attractors @xcite .
for instance , previous studies investigated retrieval of a specific pattern by neural oscillator networks @xcite . in these studies , the stable pattern was predicted by lyapunov function analysis , and the basin switching was accomplished by controlling the potential profiles . |
4,216 | Suppose that you have an abstract for a scientific paper: kuiper belt object 136108 haumea is one of the most fascinating bodies in our solar system .
approximately @xmath0 km in size , it is one of the largest kuiper belt objects ( kbos ) and an unusually elongated one for its size .
the shape of haumea is the result of rotational deformation due to its extremely short 3.9-hour rotation period . unlike other 1000 km - scale kbos which are coated in methane ice the surface of haumea
is covered in almost pure h@xmath1o - ice .
the bulk density of haumea , estimated around 2.6 g @xmath2 , suggests a more rocky interior composition , different from the h@xmath1o - ice surface .
recently , haumea has become the second kbo after pluto to show observable signs of surface features .
a region darker and redder than the average surface of haumea has been identified , the composition and origin of which remain unknown .
i discuss this recent finding and what it may tell us about haumea . .
And you have already written the first three sentences of the full article: the kuiper belt is currently the observational frontier of our solar system .
presumably the best kept remnants of the icy planetesimals that formed the outer planets , kuiper belt objects ( kbos ) have been the subjects of intense study in the past @xmath315 years .
one intriguing kbo is 136108 haumea ( formerly 2003 el@xmath4 ) ..
Please generate the next two sentences of the article | first famous for its super - fast rotation and elongated shape , haumea went on to surprise us with a host of interesting properties .
haumea s spin frequency of one rotation every @xmath5 hr is unparalleled for an object this large @xcite . |
4,217 | Suppose that you have an abstract for a scientific paper: we measure the merger fraction of massive galaxies using the ultravista / cosmos _ ks_-band selected catalog , complemented with the deeper , higher resolution 3dhst+candels catalog selected in the _ hst_/wfc3 _
h_-band , presenting the largest mass - complete photometric merger sample up to @xmath0 .
we find that selecting mergers using the @xmath1-band flux ratio leads to an increasing merger fraction with redshift , while selecting mergers using the stellar mass ratio causes a diminishing redshift dependence .
defining major and minor mergers as having stellar mass ratios of 1:1 - 4:1 and 4:1 - 10:1 respectively , the results imply @xmath21 major and @xmath31 minor merger for an average massive ( log@xmath4 ) galaxy during @xmath5 .
there may be an additional @xmath6 major ( minor ) merger if we use the @xmath7-band flux ratio selection .
the observed amount of major merging alone is sufficient to explain the observed number density evolution for the very massive ( log@xmath8 ) galaxies .
we argue that these very massive galaxies can put on a maximum of @xmath9 of stellar mass in addition to major and minor merging , so that their number density evolution remains consistent with observations .
the observed number of major and minor mergers can increase the size of a massive quiescent galaxy by a factor of two at most .
this amount of merging is enough to bring the compact quiescent galaxies formed at @xmath10 to lie at @xmath11 below the mean of the stellar mass - size relation as measured in some works ( e.g. * ? ? ?
* ) , but additional mechanisms are needed to fully explain the evolution , and to be consistent with works suggesting stronger evolution ( e.g. * ? ? ?
* ) . .
And you have already written the first three sentences of the full article: for decades , galaxy merging has been a popular explanation for the observed evolution in galaxy properties .
galaxy mergers were first invoked to explain the morphological transformation of galaxies @xcite .
merging remains the backbone in cosmological simulations in building up large galaxies ( e.g. * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
gas - rich major mergers at high redshifts ( @xmath10 ) are thought to trigger starburst and active galactic nuclei ( agn ) episodes , quench star formation , and lead to bulge formation , thereby building the massive ellipticals in the local universe @xcite . |
4,218 | Suppose that you have an abstract for a scientific paper: we present sdssj092712.65 + 294344.0 as the best candidate to date for a recoiling supermassive black hole ( smbh ) .
sdssj0927 + 2943 shows an exceptional optical emission - line spectrum with two sets of emission lines : one set of very narrow emission lines , and a second set of broad balmer and broad high - ionization forbidden lines which are blueshifted by 2650 kms@xmath0 relative to the set of narrow emission lines .
this observation is most naturally explained if the smbh was ejected from the core of the galaxy , carrying with it the broad - line gas while leaving behind the bulk of the narrow - line gas .
we show that the observed properties of sdssj0927 + 2943 are consistent with predictions and expectations from recent numerical relativity simulations which demonstrate that smbhs can receive kicks up to several thousand kms@xmath0 due to anisotropic emission of gravitational waves during the coalescence of a binary .
our detection of a strong candidate for a rapidly recoiling smbh implies that kicks large enough to remove smbhs completely from their host galaxies do occur , with important implications for models of black hole and galaxy assembly at the epoch of structure formation , and for recoil models . .
And you have already written the first three sentences of the full article: the merging of two galaxies will produce a binary black hole at the center of the newly formed galaxy .
if the two black holes do not stall , they will ultimately merge due to emission of gravitational wave radiation .
the gravitational waves carry away linear momentum , causing the centre of mass of the coalescing bh system to recoil in the opposite direction ( peres 1962 , bekenstein 1973 ) ..
Please generate the next two sentences of the article | early analytical calculations predicted that mergers of non - spinning black holes can attain kicks with velocities of up to a few hundred kms@xmath0 ( e.g. , fitchett & detweiler 1984 , favata et al .
2004 , blanchet et al . |
4,219 | Suppose that you have an abstract for a scientific paper: we report measurements of the charmless semileptonic decays @xmath0 and @xmath1 , based on a sample of @xmath2 @xmath3 events collected at the @xmath4 resonance with the belle detector at the kekb @xmath5 asymmetric collider . in this analysis ,
the accompanying @xmath6 meson is reconstructed in the semileptonic mode @xmath7 , enabling detection of the signal modes with high purity .
we measure the branching fractions @xmath8 , @xmath9 , @xmath10 and @xmath11 , where the errors are statistical , experimental systematic , and systematic due to form - factor uncertainties , respectively . for each mode we also present the partial branching fractions in three @xmath12 intervals : @xmath13 , @xmath14 , and @xmath15gev@xmath16 . from our partial branching fractions for @xmath17 and recent results for the form factor from unquenched lattice qcd calculations ,
we obtain values of the ckm matrix element @xmath18 . 2.cm -1.5 cm belle prerpint 2006 - 10 + kek preprint 2006 - 4 , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , and , semileptonic , b decay , exclusive 12.15.hh , 12.38.gc , 13.25.hw .
And you have already written the first three sentences of the full article: exclusive @xmath19 decays proceed dominantly via a @xmath20 tree process and can be used to determine @xmath18 , one of the smallest and least known elements of the cabibbo - kobayashi - maskawa matrix @xcite .
however , the need to translate the observed rate to a @xmath18 value using model - dependent decay form - factors ( ff ) has resulted in large theoretical uncertainties .
the recent release of ff results for @xmath17 calculated by unquenched lattice qcd ( lqcd ) @xcite makes possible the first model - independent determination of @xmath18 ..
Please generate the next two sentences of the article | since lqcd results are available only in the high @xmath12 region ( @xmath21gev@xmath16 ) , a clean measurement of the partial @xmath17 branching fraction in the same high @xmath12 region is needed
. there have been several measurements in the past by cleo , babar and belle for the @xmath17 , @xmath22 , @xmath23 and @xmath24 modes @xcite . |
4,220 | Suppose that you have an abstract for a scientific paper: we have measured , using a custom setup , the emissivity of metallic wire - grids , suitable for polarimeters and interferometers at mm and far infrared wavelengths .
we find that the effective emissivity of these devices is of the order of a few @xmath0 , depending on fabrication technology and aging .
we discuss their use in astronomical instruments , with special attention to martin puplett interferometers in low - background applications , like astronomical observations of the cosmic microwave background .
polarizers , interferometers , cosmic microwave background .
And you have already written the first three sentences of the full article: wire - grid ( wg ) polarizers are widely used at mm - wavelengths as efficient polarization analyzers in polarimeters ( see e.g. @xcite ) , or as beamsplitters in martin - puplett interferometers ( mpi , see @xcite ) .
in fact , an array of metallic wires with diameter and spacing much smaller than the wavelength performs as an almost ideal polarizer at mm wavelengths ( see e.g. @xcite ) , providing an almost ideal beamsplitter for mpis . in the case of astronomical observations ,
low - background operation is required , to observe the faintest sources . in general , fourier transform spectrometers ( fts ) like the mpi can measure a very wide frequency range , often covering up to two decades in frequency ..
Please generate the next two sentences of the article | this is an evident advantage with respect to dispersion and fabry - perot spectrometers , but comes at the cost of a higher radiative background on the detector , which is constantly illuminated by radiation from the whole frequency range covered .
for this reason the best performing instruments are cooled at cryogenic temperatures , and are operated aboard of space carriers to avoid the background and noise produced by the earth atmosphere . |
4,221 | Suppose that you have an abstract for a scientific paper: a spontaneous vortex state ( svs ) between 30 k and 56 k was observed for the weak - ferromagnetic superconductor rusr@xmath0gdcu@xmath0o@xmath1 with ferromagnetic curie temperature t@xmath2 = 131 k and superconducting transition temperature t@xmath3 = 56 k. the low field ( @xmath420 g ) superconducting hysteresis loop indicates a narrow meissner state region within average lower critical field b@xmath5(t)= b@xmath5(0)[1 - ( t / t@xmath6)@xmath7 , with average b@xmath8(0 ) = 12
g and t@xmath6 = 30 k. full meissner shielding signal in very low applied field indicates an ab - plane b@xmath9(0 ) @xmath10 4 g with an estimated anisotropic parameter @xmath11 7 for this layered system .
the existence of a spontaneous vortex state between 30 k and 56 k is the result of weak - ferromagnetic order with a net spontaneous magnetic moment of @xmath10 0.1 @xmath12/ru , which generates a weak magnetic dipole field around 10 g in the cuo@xmath0 bi - layers .
the upper critical field b@xmath13 varies linearly as ( 1 - t / t@xmath3 ) up to 7-t field .
the vortex melting line b@xmath14 varies as ( 1 - t / t@xmath14)@xmath15 with melting transition temperature t@xmath14 = 39 k and a very broad vortex liquid region due to the coexistence and the interplay between superconductivity and weak - ferromagnetic order . .
And you have already written the first three sentences of the full article: recently , high - t@xmath3 superconductivity with anomalous magnetic properties was reported in the weak - ferromagnetic ru-1212 system rusr@xmath0rcu@xmath0o@xmath1 ( r = sm , eu , gd , y ) with the tetragonal tlba@xmath0cacu@xmath0o@xmath16-type structure.@xcite for the ca - substituted system , a possible superconductivity was also reported in the weak - ferromagnetic compounds ruca@xmath0rcu@xmath0o@xmath1 ( r = pr - gd).@xcite the metallic weak - ferromagnetic ( wfm ) order is originated from the long range order of ru moments in the ruo@xmath17 octahedra due to strong ru-4d@xmath18-o-2p@xmath19 hybridization in this strongly - correlated electron system .
the curie temperature t@xmath20 130 k observed from magnetization measurement in the prototype compound rusr@xmath0gdcu@xmath0o@xmath1 is probably a canted g - type antiferromagnetic order with ru@xmath21 moment @xmath22 canted along the tetragonal basal plane resulting a small net spontaneous magnetic moment @xmath23 @xmath24(ru@xmath21 ) too small to be detected in neutron diffraction.@xcite the occurrence of high - t@xmath3 superconductivity with maximum resistivity onset t@xmath3(onset ) @xmath10 60 k in rusr@xmath0gdcu@xmath0o@xmath1 is related with the quasi - two - dimensional cuo@xmath0 bi - layers separated by a rare earth layer in the ru-1212 structure.@xcite broad resistivity transition width @xmath25t@xmath3 = t@xmath3(onset ) - t@xmath3(zero ) @xmath10 15 - 20 k observed is most likely originated from the coexistence and the interplay between superconductivity and weak - ferromagnetic order.@xcite the diamagnetic t@xmath3 is observed anomalously at lower temperature near t@xmath3(zero ) instead of at t@xmath3(onset ) , and a reasonable large meissner signal was reported using stationary sample magnetometer with diamagnetic t@xmath26 30 k in @xmath27 1
g applied field at zero - field - cooled ( zfc ) mode.@xcite lower t@xmath3(onset ) @xmath10 40 k and 12 k were observed for rusr@xmath0eucu@xmath0o@xmath1 and rusr@xmath0smcu@xmath0o@xmath1....
Please generate the next two sentences of the article | the stoichiometric rusr@xmath0gdcu@xmath0o@xmath1 samples were synthesized by the standard solid - state reaction method .
high - purity ruo@xmath0 ( 99.99 @xmath28 ) , srco@xmath29 ( 99.99 @xmath28 ) , gd@xmath0o@xmath29 ( 99.99 @xmath28 ) , and cuo ( 99.99 @xmath28 ) preheated powders with the nominal composition ratio of ru : sr : gd : cu = 1 : 2 : 1 : 2 were well mixed and calcined at 960@xmath30c in air for 16 hours . |
4,222 | Suppose that you have an abstract for a scientific paper: laser - driven collisonless electrostatic shock formation and the subsequent ion acceleration have been studied in near critical density plasmas .
particle - in - cell simulations show that both the speed of laser - driven collisionless electrostatic shock and the energies of shock - accelerated ions can be greatly enhanced due to fast laser propagation in near critical density plasmas .
however , a response time longer than tens of laser wave cycles is required before the shock formation in a near critical density plasma , in contrast to the quick shock formation in a highly overdense target .
more important , we find that some ions can be reflected by the collisionless shock even if the electrostatic potential jump across the shock is smaller than the ion kinetic energy in the shock frame , which seems against the conventional ion - reflection condition .
these anomalous ion reflections are attributed to the strongly time - oscillating electric field accompanying laser - driven collisionless shock in a near critical density plasma . .
And you have already written the first three sentences of the full article: collisionless shocks driven by intense laser pulses attract growing attention from both laboratory astrophysics @xcite and plasma - based accelerator communities @xcite . in astrophysics , collisionless shocks
are observed in supernova remnants , gamma ray bursts , active galactic nucleus jets and so on @xcite .
particularly , collisionless shocks are relevant to the generation of extremely high energy particles , which is one of the most fundamental problems in astrophysics @xcite ..
Please generate the next two sentences of the article | however , the direct study of collisionless shocks in astronomical environments is passive and suffers from the lack of details .
in contrast , high power laser - matter interaction can create astrophysical - like conditions and thus provides convenient test - beds for many astrophysical processes including the collisionless shock formation @xcite . with regard to plasma - based accelerator , |
4,223 | Suppose that you have an abstract for a scientific paper: we have observed 70 galaxies belonging to 45 hickson compact groups in the and lines , in order to determine their molecular content .
we detected 57 galaxies , corresponding to a detection rate of 81% .
we compare the gas content relative to blue and luminosities of galaxies in compact groups with respect to other samples in the literature , including various environments and morphological types .
we find that there is some hint of enhanced / and / ratios in the galaxies from compact group with respect to our control sample , especially for the most compact groups , suggesting that tidal interactions can drive the gas component inwards , by removing its angular momentum , and concentrating it in the dense central regions , where it is easily detected .
the molecular gas content in compact group galaxies is similar to that in pairs and starburst samples .
however , the total luminosity of hcgs is quite similar to that of the control sample , and therefore the star formation efficiency appears lower than in the control galaxies .
however this assumes that the fir spatial distributions are similar in both samples which is not the case at radio frequencies .
higher spatial resolution fir data are needed to make a valid comparison . given their short dynamical friction time - scale , it is possible that some of these systems are in the final stage before merging , leading to ultra - luminous starburst phases .
we also find for all galaxy samples that the content ( derived from co luminosity and normalised to blue luminosity ) is strongly correlated to the luminosity , while the total gas content ( + ) is not . .
And you have already written the first three sentences of the full article: galaxies are gregarious systems , most of them are gathered in groups or clusters , while only 30% are isolated and 10% are binaries in the field .
nevertheless compact groups ( cg ) are quite rare and according to hickson s classification ( hickson , 1982 ) only 0.1 % of galaxies belong to cgs .
criteria of population ( initially four galaxies in the group ) , isolation ( dynamically independent systems ) and compactness ( separation between galaxies comparable to the sizes of the galaxies ) are chosen by hickson to build his catalog . with these criteria around one hundred cgs were found on the palomar observatory sky survey red prints ..
Please generate the next two sentences of the article | compact groups are ideal sites to study the influence of strong dynamical evolution due to environment on molecular cloud formation and star formation efficiency .
they appear in projection as the densest galaxy systems known , even denser than the cores of rich clusters , and they show multiple signs of interactions . due to their high density , and relatively small velocity dispersion , these systems are unstable with regard to merging instability . |
4,224 | Suppose that you have an abstract for a scientific paper: in recent papers , we have argued that kinetically constrained coarse grained models can be applied to understand dynamic properties of glass forming materials , and we have used this approach in various applications that appear to validate this view . in one such paper [ j.p .
garrahan and d. chandler , proc .
nat .
acad .
sci .
usa * 100 * , 9710 ( 2003 ) ] , among other things we argued that this approach also explains why the heat capacity discontinuity at the glass transition is generally larger for fragile materials than for strong materials . in the preceding article , biroli , bouchaud and tarjus ( bb&t ) have objected to our explanation on this point , arguing that the class of models we apply is inconsistent with both the absolute size and temperature dependence of the experimental specific heat .
their argument , however , neglects parameters associated with the coarse graining . accounting for these parameters ,
we show here that our treatment of dynamics is not inconsistent with heat capacity discontinuities . .
And you have already written the first three sentences of the full article: many workers argue that a thermodynamic anomaly underlies the onset of glassy dynamics @xcite .
evidence for this view is the rough , though not quantitative @xcite , correlation between dynamic fragility and excess heat capacity discontinuity @xcite .
this thermodynamic view contrasts with the picture we have advocated @xcite , attributing glassy behavior to dynamic heterogeneity @xcite , with growing length scales appearing in space - time , but not space alone @xcite . indeed ,.
Please generate the next two sentences of the article | direct observations of diffusive motion in colloidal glasses reveal excitations that are local and sparse @xcite .
these findings seem consistent with excitations being local and uncorrelated , as assumed in the two - state model for the low temperature behavior of structural glass heat capacities @xcite . |
4,225 | Suppose that you have an abstract for a scientific paper: several new estimation methods have been recently proposed for the linear regression model with observation error in the design .
different assumptions on the data generating process have motivated different estimators and analysis .
in particular , the literature considered ( 1 ) observation errors in the design uniformly bounded by some @xmath0 , and ( 2 ) zero mean independent observation errors . under the first assumption ,
the rates of convergence of the proposed estimators depend explicitly on @xmath0 , while the second assumption has been applied when an estimator for the second moment of the observational error is available .
this work proposes and studies two new estimators which , compared to other procedures for regression models with errors in the design , exploit an additional @xmath1-norm regularization .
the first estimator is applicable when both ( 1 ) and ( 2 ) hold but does not require an estimator for the second moment of the observational error .
the second estimator is applicable under ( 2 ) and requires an estimator for the second moment of the observation error .
importantly , we impose no assumption on the accuracy of this pilot estimator , in contrast to the previously known procedures .
as the recent proposals , we allow the number of covariates to be much larger than the sample size .
we establish the rates of convergence of the estimators and compare them with the bounds obtained for related estimators in the literature .
these comparisons show interesting insights on the interplay of the assumptions and the achievable rates of convergence . .
And you have already written the first three sentences of the full article: several new estimation methods have been recently proposed for the linear regression model with observation error in the design .
such problems arise in a variety of applications , see @xcite . in this work
we consider the following regression model with observation error in the design : @xmath2 here the random vector @xmath3 and the random @xmath4 matrix @xmath5 are observed , the @xmath4 matrix @xmath6 is unknown , @xmath7 is an @xmath4 random noise matrix , and @xmath8 is a random noise vector ..
Please generate the next two sentences of the article | the vector of unknown parameters of interest is @xmath9 which is assumed to belong to a given convex subset @xmath10 of @xmath11 characterizing some prior knowledge about @xmath9 ( potentially @xmath12 ) .
similarly to the recent literature on this topic , we consider the setting where the dimension @xmath13 can be much larger than the sample size @xmath14 and the vector @xmath9 is @xmath15-sparse , which means that it has not more than @xmath15 non - zero components . |
4,226 | Suppose that you have an abstract for a scientific paper: it is shown that in the complex trajectory representation of quantum mechanics , the born s @xmath0 probability density can be obtained from the imaginary part of the velocity field of particles on the real axis . extending this probability axiom to the complex plane , we first attempt to find a probability density by solving an appropriate conservation equation .
the characteristic curves of this conservation equation are found to be the same as the complex paths of particles in the new representation .
the boundary condition in this case is that the extended probability density should agree with the quantum probability rule along the real line . for the simple , time - independent
, one - dimensional problems worked out here , we find that a conserved probability density can be derived from the velocity field of particles , except in regions where the trajectories were previously suspected to be nonviable .
an alternative method to find this probability density in terms of a trajectory integral , which is easier to implement on a computer and useful for single particle solutions , is also presented .
most importantly , we show , by using the complex extension of schrodinger equation , that the desired conservation equation can be derived from this definition of probability density . quantum hamilton - jacobi equation , trajectory representation , probability axiom , complex methods 03.65.ca .
And you have already written the first three sentences of the full article: in a previous work @xcite , the quantum hamilton - jacobi equation [ 2 - 5 ] ( qhje ) was made use of to demonstrate the existence of particle trajectories in a complex space , for different quantum states .
this complex quantum trajectory representation was obtained by modifying the de broglie - bohm ( dbb ) approach to quantum mechanics @xcite , which allows particle motion guided by the wave function .
one of the advantages of the resulting theory , which offers a new interpretation of quantum mechanics , is that it does not face the problem of stationarity of particles in bound states , encountered in the dbb representation ..
Please generate the next two sentences of the article | another trajectory approach to quantum mechanics , which also claims the absence of this problem , is the representation developed by floyd , faraggi , matone ( ffm ) and others [ 7 - 9 ] .
the new complex trajectory representation proceeds by first substituting @xmath1 in the schrodinger equation to obtain the quantum hamilton - jacobi equation @xmath2 = \frac{i\hbar}{2 m } \frac{\partial^2 \hat{s}}{\partial x^2 } , \label{eq : qhje}\ ] ] and then postulating an equation of motion @xmath3 for the particle . |
4,227 | Suppose that you have an abstract for a scientific paper: we establish rigorous upper and lower bounds for the speed of pulled fronts with a cutoff .
we show that the brunet - derrida formula corresponds to the leading order expansion in the cut - off parameter of both the upper and lower bounds . for
sufficiently large cut - off parameter the brunet - derrida formula lies outside the allowed band determined from the bounds . if nonlinearities are neglected the upper and lower bounds coincide and are the exact linear speed for all values of the cut - off parameter .
the reaction diffusion equation @xmath0 provides a simple description of phenomena in fields such as population dynamics , chemical reactions , flame propagation , fluids , qcd , among others @xcite .
it is one of the simplest models which shows how a small perturbation to an unstable state develops into a moving front joining a stable to an unstable state .
the reaction term @xmath1 satisfies different conditions depending on the physical problem of interest .
one of the first , and most studied cases , is the fisher reaction term @xmath2 for which the asymptotic speed of the propagating front is @xmath3 , a value determined from linear considerations .
a more general case was studied by kolmogorov , petrovskii and piscounov ( kpp)@xcite who showed that for all reaction terms which satisfy the kpp condition @xmath4 the asymptotic speed of the front joining the stable @xmath5 point to the unstable @xmath6 point is given by @xmath7 these fronts are called pulled since it is the leading edge of the front which determines the velocity of propagation . in the rest of this work
we assume that @xmath8 .
the evolution of localized initial conditions for general reaction terms , and rigorous properties of the fronts were studied by aronson and weinberger @xcite .
the asymptotic speed of the front for all reaction terms can be found from the integral variational principle @xcite @xmath9 where the supremum is taken over all positive monotonic decreasing functions @xmath10 for which the....
And you have already written the first three sentences of the full article: we acknowledge partial support of fondecyt ( chile ) projects 1060627 and 1060651 , conicyt / pbct proyecto anillo de investigacin en ciencia y tecnologa act30/2006 and u.s .
national science foundation grant dms 06 - 00037 ..
Please generate the next two sentences of the article | |
4,228 | Suppose that you have an abstract for a scientific paper: in this communication we present statistical analysis of conservation profiles in families of homologous sequences for nine proteins whose folding nucleus was determined by protein engineering methods .
we show that in all but one protein ( acp ) folding nucleus residues are significantly more conserved than the rest of the protein .
two aspects of our study are especially important : 1 ) grouping of amino acids into classes according to their physical - chemical properties and 2 ) proper normalization of amino acid probabilities that reflects the fact that evolutionary pressure to conserve some amino acid types may itself affect concentration of various amino acid types in protein families
. neglect of any of those two factors may make physical and biological `` signals '' from conservation profiles disappear .
epsf running title : conservation of folding nucleus submitted to _
journal of molecular biology _ harvard university , department of + chemistry and chemical biology + 12 oxford street , cambridge ma 02138 + .
And you have already written the first three sentences of the full article: it is now widely accepted that folding of small single - domain proteins follows `` nucleation - condensation '' mechanism @xcite whereby relatively small fragment of protein structure is formed in the transition state between unfolded and folded states .
residues belonging to this fragment constitute specific folding nucleus ( sfn ) .
considerable experimental @xcite and theoretical @xcite effort has been devoted to identification of folding nuclei in real proteins and various models as well as factors that determine its location in structure and in sequence ..
Please generate the next two sentences of the article | one of the most intriguing aspect of nucleation - condensation mechanism of protein folding is its relation to protein evolution .
indeed residues constituting folding nucleus can be metaphorically considered `` accelerator pedals '' of folding @xcite since mutations in those positions affect folding rate to a much greater extent than elsewhere in a protein . |
4,229 | Suppose that you have an abstract for a scientific paper: inspired by the notion that environmental noise is in principle observable , whilst fundamental noise due to spontaneous localisation would not be , we study the estimation of the diffusion parameter induced by wave function collapse models under continuous monitoring of the environment .
we take into account finite measurement efficiencies and , in order to quantify the advantage granted by monitoring , we analyse the quantum fisher information associated with such a diffusion parameter , identify optimal measurements in limiting cases , and assess the performance of such measurements in more realistic conditions . _
introduction . _ - spontaneous localization models @xcite , in their many flavours and variations , were introduced from the late eighties primarily as an attempt to unify the dynamics of microscopic and macroscopic systems , encompassing measurement apparata , which customary quantum mechanics only describes through ad hoc prescriptions that can not be relied to the fundamental dynamical principles .
while such models reproduce quantum and classical mechanics in the extreme regimes of few ( @xmath0 ) and very many ( @xmath1 ) elementary constituents , they do deviate substantially from standard quantum mechanics in the intermediate mesoscopic regime . as molecular interferometry @xcite and quantum opto - mechanics , especially in the levitating paradigm @xcite , are swiftly advancing into this mesoscopic middle ground , there is currently a lively interest in designing and carrying out experiments that would falsify either standard quantum mechanics or its spontaneously localized variants @xcite . in a nutshell ,
spontaneous localization models postulate the presence of an additional stochastic term in the schrdinger equation , that would be responsible for the wave - function collapse and the perceived discontinuous dynamics of quantum projective measurements .
this would essentially imply the existence of a source of `` fundamental '' decoherence , in the form of momentum....
And you have already written the first three sentences of the full article: here we will provide the formulas describing the time - evolution of the mechanical oscillator along with the formula for the qfi of the steady state . assuming that the mechanical oscillator is continuously monitored with efficiency @xmath19 , the evolution is described by the following stochastic master equation @xmath83 \ : dt+ ( \gamma_{\sf env } + \gamma_{\sf fun } ) \ : \mathcal{d}[\hat{x}]\varrho \ : dt \nonumber \\ & \qquad + \sqrt{\eta \gamma_{\sf env } } \mathcal{h}[\hat{x } ] \varrho \ : dw \label{eq : smesm}\end{aligned}\ ] ] where @xmath6 , @xmath7\varrho = o\varrho o^\dag - ( o^\dag o \varrho + \varrho o^\dag o)/2 $ ] and @xmath20\varrho = o \varrho + \varrho o^\dag - \tr[(o+o^\dag)\varrho]$ ] . this equation can be translated in the following equations for first moments and covariance matrix , fully describing the evolution for gaussian quantum states @xmath84 where @xmath85 is a vector of wiener increments such that @xmath86 and the matrices read @xmath87 the steady state covariance matrix can be derived analytically as @xmath88 where @xmath89 notice that , typically , the steady state above is a squeezed state , in the sense that its smallest eigenvalue will be smaller than one . obtaining the decomposition , in terms of diagonal single - mode squeezers and orthogonal phase shifters , of the symplectic operation that relates the vacuum state to this steady state is a straightforward task , that just requires one to diagonalise the matrix @xmath46 .
the corresponding quantum fisher information can be easily evaluated by using the formula @xcite @xmath90}{1+\mu_\phi^2 } + 2 \frac{(\mu_{\sf ss}^{\prime})^2}{1-\mu_{\sf ss}^4 } \ : , \label{eq : gaussqfi}\end{aligned}\ ] ] where @xmath91 = 1/\sqrt{\det[\sigmacm_{\sf ss}]}$ ] represents the purity of the state , and primed quantities corresponds to derivative with respect to the parameter @xmath10 .
one then obtains @xmath92 + \gamma_{\sf fun } \left ( \omega_m - 3 \upsilon\right ) } { 8\upsilon ( \gamma_{\sf env } + \gamma_{\sf fun } ) \left....
Please generate the next two sentences of the article | |
4,230 | Suppose that you have an abstract for a scientific paper: we present a slave - particle mean - field study of the mixed boson+fermion quantum dimer model introduced by punk , allais , and sachdev [ pnas * 112 * , 9552 ( 2015 ) ] to describe the physics of the pseudogap phase in cuprate superconductors .
our analysis naturally leads to four charge @xmath0 fermion pockets whose total area is equal to the hole doping @xmath1 , for a range of parameters consistent with the @xmath2 model for high temperature superconductivity . here
we find that the dimers are unstable to d - wave superconductivity at low temperatures .
the region of the phase diagram with d - wave rather than s - wave superconductivity matches well with the appearance of the four fermion pockets . in the superconducting regime ,
the dispersion contains eight dirac cones along the diagonals of the brillouin zone . _
[ introduction]introduction . _ the rokhsar - kivelson quantum dimer model ( qdm ) was originally introduced to describe a possible magnetically - disordered phase the resonating valence bond ( rvb ) phase in high - temperature superconducting materials @xcite .
the arena where the qdm has been deployed has greatly expanded since its inception , and the model has taken on a key role in the study of a variety of magnetic quantum systems .
quantum dimers show up prominently in the study of hard - core bosons hopping on frustrated lattices @xcite , of arrays of josephson junctions with capacitative and josephson couplings @xcite , of frustrated ising models with an external field or with perturbative xy couplings @xcite , of various types of gauge theories @xcite , and of models with large spin - orbit couplings @xcite and various cold atom setups @xcite .
the study of qdms led to an abundance of new phenomena including deconfined quantum criticality and new routes to deconfinement @xcite .
it also provided one of the earliest known examples of topologically ordered states in a lattice model @xcite .
recently qdms have been revisited as models of high -....
And you have already written the first three sentences of the full article: here we provide more details about the derivation of the effective two body ( four fermion ) interaction introduced in eq . in the main text .
the procedure to obtain this term for the dimer model is to identify the dimer hilbert space with a subspace of the @xmath2 model hilbert space and project the @xmath2 hamiltonian eq . accordingly .
we identify the state with zero dimers of any kind with the state with zero electrons for the @xmath2 model ..
Please generate the next two sentences of the article | the rest of the hilbert space for the dimers can be introduced via the operators @xmath79 and @xmath80 .
the phases @xmath81 represent a gauge choice and we shall follow the one by rokhsar and kivelson @xcite and define @xmath82 and @xmath83 , here @xmath84 is the y - component of the dimer co - ordinate . given the conventional inner product for the electron hilbert space , |
4,231 | Suppose that you have an abstract for a scientific paper: rx j1713.7@xmath03946 is a prototype in the @xmath1-ray - bright supernova remnants ( snrs ) and is in continuing debates on its hadronic versus leptonic origin of the @xmath1-ray emission .
we explore the role played by the diffusive relativistic protons that escape from the snr shock wave in the @xmath1-ray emission , apart from the high - energy particles emission from the inside of the snr . in the scenario that the snr shock propagates in a clumpy molecular cavity , we consider that the @xmath1-ray emission from the inside of the snr may arise either from the inverse compton scattering or from the interaction between the trapped energetic protons and the shocked clumps .
the dominant origin between them depends on the electron - to - proton number ratio .
the diffusive protons that escaped from the shock wave during the expansion history can provide an outer hadronic @xmath1-ray component by bombarding the surrounding dense matter .
the broadband spectrum can be well explained by this two - zone model , in which the @xmath1-ray emission from the inside governs the tev band , while the outer emission component substantially contributes to the gev @xmath1-rays .
the two - zone model can also explain the tev @xmath1-ray radial brightness profile that significantly stretches beyond the nonthermal x - ray - emitting region . in the calculation
, we present a simplified algorithm for @xcite s ( 2010 ) accumulative diffusion " model for escaping protons and apply the markov chain monte carlo method to constrain the physical parameters . .
And you have already written the first three sentences of the full article: it is usually believed that galactic supernova remnants ( snrs ) are the main accelerators of cosmic rays ( crs , mainly protons ) and can boost particles up to the knee " energy of @xmath23 @xmath3 ev through the diffusive shock acceleration ( dsa ) .
an important probe of this conjecture is the hadronic @xmath1-ray emission ( namely , @xmath4-decay @xmath1-rays produced in the inelastic collision between the accelerated protons and the target baryons ) from the snrs that interact with molecular clouds ( mcs ) .
fortunately , great progress has been made in understanding the snr paradigm by the detection of a characteristic @xmath5-decay bump " in the interacting snrs ic 443 @xcite and w44 @xcite . yet.
Please generate the next two sentences of the article | , multifaceted investigations of hadronic interaction are still needed to increase and strengthen the evidence for the paradigm in a large sample of snr - mc association systems ( e.g. , * ? ? ?
it is , however , often uneasy to distinguish the nature of the @xmath1-rays between the hadronic scenario and leptonic ( inverse compton [ ic ] and/or bremsstrahlung ) scenario even in the snr - mc systems , such as snr rx j1713.7@xmath03946 , and deep explorations for the spectral properties and emitting mechanism of them in the gev tev range are essential . |
4,232 | Suppose that you have an abstract for a scientific paper: the expected proton and neutrino fluxes from decays of massive metastable relic particles are calculated using the herwig qcd event generator .
the predicted proton spectrum can account for the observed flux of extremely high energy cosmic rays beyond the greisen - zatsepin - kuzmin cutoff , for a decaying particle mass of @xmath0 gev .
the lifetime required is of @xmath1 yr if such particles constitute all of the dark matter ( with a proportionally shorter lifetime for a smaller contribution ) .
such values are plausible if the metastable particles are hadron - like bound states from the hidden sector of supersymmetry breaking which decay through non - renormalizable interactions .
the expected ratio of the proton to neutrino flux is given as a diagonistic of the decaying particle model for the forthcoming pierre auger project . -3cm^-3 .
And you have already written the first three sentences of the full article: it has been known for some time that interactions on the 2.73 k blackbody cosmic microwave background ( cmb ) will severely degrade the energies of cosmic ray nucleons with energies beyond @xmath2 the greisen - zatsepin - kuzmin ( gzk ) cutoff @xcite .
it was therefore very surprising when the fly s eye atmospheric fluorescence detector reported the observation of an extremely high energy cosmic ray ( ehecr ) event with an energy of @xmath3 @xcite .
this was followed by the detection of a @xmath4 event by the agasa air shower array @xcite ..
Please generate the next two sentences of the article | these discoveries substantiated earlier claims from the volcano ranch @xcite , haverah park @xcite and yakutsk @xcite air shower arrays that cosmic rays do exist beyond the gzk cutoff .
about a dozen such events are now known . |
4,233 | Suppose that you have an abstract for a scientific paper: we consider the effect of electron - electron interactions on the current - in - plane ( cip ) conductivity and exchange coupling energy of a disordered metallic magnetic multilayer .
we analyze its dependence on the value of ferromagnetic splitting of conducting electrons and ferromagnetic layers relative magnetizations orientation .
we show that contribution to the cip conductivity and exchange coupling energy as a periodic function of the angle of magnetizations relative orientation experience @xmath0 transition depending on the characteristic energies : ferromagnetic splitting of the conducting electrons and the thouless energy of paramagnetic layer . .
And you have already written the first three sentences of the full article: the most interesting features of perfect metallic magnetic multilayer are the oscillatory behavior of bilinear exchange coupling energy between ferromagnets @xcite due to friedel oscillations , and large magnetoresistance in small magnetic fields @xcite . the magnetic structure of adjoining magnetic layers in perfect multilayered structure oscillates between ferro and antiferro - magnetic states with increasing the spacer thickness @xmath1 . disorder in layers contributes to biquadratic exchange coupling .
it was shown that fluctuations of thickness of the paramagnetic layer give rise to biquadratic exchange coupling , often leading to non - collinear magnetic ordering @xcite . in ref .
the role of scattering of conducting electrons by impurities in metallic magnetic multilayer was studied ..
Please generate the next two sentences of the article | it was pointed out that in the case of small ( compared to thickness of the layers ) mean free path of conducting electrons , when average friedel oscillations are exponentially suppressed , the exchange coupling energy due to random friedel oscillations and correlation effects can have biquadratic form .
transition to the non - collinear phase in disordered structure with increasing @xmath1 was experimentally observed in ref . . |
4,234 | Suppose that you have an abstract for a scientific paper: measurements of charged pion and kaon production in central pb+pb collisions at 40 , 80 and 158 @xmath0gev are presented .
these are compared with data at lower and higher energies as well as with results from @xmath1 interactions .
the mean pion multiplicity per wounded nucleon increases approximately linearly with @xmath2 with a change of slope starting in the region 1540 @xmath0gev .
the change from pion suppression with respect to @xmath1 interactions , as observed at low collision energies , to pion enhancement at high energies occurs at about 40 @xmath0gev .
a non monotonic energy dependence of the ratio of @xmath3 to @xmath4 yields is observed , with a maximum close to 40 @xmath0gev and an indication of a nearly constant value at higher energies .
the measured dependences may be related to an increase of the entropy production and a decrease of the strangeness to entropy ratio in central pb+pb collisions in the low sps energy range , which is consistent with the hypothesis that a transient state of deconfined matter is created above these energies .
other interpretations of the data are also discussed . = -1.5 cm * energy dependence of * * pion and kaon production * * in central pb+pb collisions * * the na49 collaboration * * the na49 collaboration * s.v .
afanasiev@xmath5,t .
anticic@xmath6 , d. barna@xmath7 , j. bartke@xmath8 , r.a .
barton@xmath9 , m. behler@xmath10 , l. betev@xmath11 , h. biakowska@xmath12 , a. billmeier@xmath11 , c. blume@xmath13 , c.o .
blyth@xmath9 , b. boimska@xmath12 , m. botje@xmath14 , j. bracinik@xmath15 , r. bramm@xmath11 , r. brun@xmath16 , p. buni@xmath17 , v. cerny@xmath15 , j.g .
cramer@xmath18 , p. csat@xmath7 , p. dinkelaker@xmath11 , v. eckardt@xmath19 , p. filip@xmath19 , z. fodor@xmath7 , p. foka@xmath13 , p. freund@xmath19 , v. friese@xmath10 , j. gl@xmath7 , m. gadzicki@xmath11 , g. georgopoulos@xmath20 , e. gadysz@xmath8 , s. hegyi@xmath7 , c. hhne@xmath10 , g. igo@xmath21 , p.g .
....
And you have already written the first three sentences of the full article: the primary purpose of the heavy ion programme at the cern sps is the search for a transient deconfined state of strongly interacting matter during the early stage of nucleus nucleus collisions @xcite .
when a sufficiently high initial energy density is reached , the formation of such a state of quasi free quarks and gluons , the quark gluon plasma ( qgp ) , is expected .
a key problem is the identification of experimental signatures of qgp creation @xcite ..
Please generate the next two sentences of the article | numerous proposals were discussed in the past @xcite , but the significance of these signals has come under renewed scrutiny . a possible , promising strategy is a study of the energy dependence of pion and strangeness yields .
it was suggested @xcite that the transition may lead to anomalies in this dependence : a steepening of the increase of the pion yield and a non monotonic behaviour of the strangeness to pion ratio . |
4,235 | Suppose that you have an abstract for a scientific paper: we investigate the dynamics of model microswimmers under confinement , in cylindrical geometries , by means of three dimensional direct numerical calculations with fully resolved hydrodynamics .
such swimmers are known to show collective alignment in bulk , and we confirmed that similar alignment can be observed even in pipes , although the volume fraction dependency shows qualitative differences . by comparing the structural information , we investigated the cause of such differences .
we found an order / disorder phase transition for a specific type of swimmers , as the size of the pipe becomes comparable to the size of the swimmers .
such dynamics are found not to depend on the geometry of confinement . .
And you have already written the first three sentences of the full article: self - propelled particles ( spps ) are attracting more and more interest as a representative example of out - of - equilibrium systems@xcite .
examples of spps range from the microscopic scale , with algae and bacteria , to the macroscopic scale , which includes all animals , and recently , even artificial spps have been constructed , such as active janus particles@xcite . among them , microswimmers are of particular interest , since they are suited to well - controlled lab experiments@xcite , and have many potential applications , for example , as targeted drug delivery systems .
it is known that nontrivial motion , like the collective alignment of the swimming direction or the dynamic clustering can be observed , even for systems where particles interact with each other only through hydrodynamic interactions and excluded volume effects@xcite ..
Please generate the next two sentences of the article | such collective motion is mainly due to the complicated hydrodynamic interactions , and can not be predicted only from knowledge of the single particle dynamics . that these hydrodynamic interactions are strongly affected by the presence of confining walls is well known .
experimentally , das _ |
4,236 | Suppose that you have an abstract for a scientific paper: we resonantly inject polaritons into a microcavity and track them in time and space as they feel a force due to the cavity gradient .
this is an example of `` slow reflection , '' as the polaritons , which can be viewed as renormalized photons , slow down to zero velocity and then move back in the opposite direction .
these measurements accurately measure the lifetime of the polaritons in our samples , which is 180 @xmath0 10 ps , corresponding to a cavity leakage time of 135 ps and a cavity @xmath1 of 320,000 .
such long - lived polaritons propagate millimeters in these wedge - shaped microcavities .
additionally , we generate polaritons by two - photon excitation directly into the polariton states , allowing the possibility of modulation of the two - photon absorption by a polariton condensate . .
And you have already written the first three sentences of the full article: since the initial observation of exciton - polaritons in a strongly coupled microcavity in 1992 @xcite , a wide range of quantum many - body effects have been observed in polariton fluids such as bose - einstein condensation @xcite , and superfluidity exhibiting quantized vortices @xcite and solitons@xcite .
most of these results have been interpreted in terms of nonequilibrium bose gas theory , because the thermalization of the polaritons has been limited by their short cavity lifetime , on the order of 10 ps , compared to a thermalization time of the order of 1 ps .
our recent results @xcite have indicated that we can now produce structures which allow much longer lifetime , of the order of 200 ps . here.
Please generate the next two sentences of the article | we report on accurate measurements of this lifetime using a unique method in which we inject polariton pulses at finite momentum into a microcavity and track their motion in time and space .
this allows us to observe `` slow reflection , '' in which renormalized light slows down to zero velocity , turns around , and goes back the other way . |
4,237 | Suppose that you have an abstract for a scientific paper: this paper provides the simulated floating zone ( sfz ) method that is an efficient simulation technique to obtain thermal equilibrium states , especially useful when domain formation prevents the system from reaching a spatially - uniform stable state . in the sfz method ,
the system is heated up locally , and the heated region is steadily shifted , similar to the floating zone method for growing a single crystal with less lattice defect and impurity in experiments .
we demonstrate that the sfz method suppresses domain formation and accelerates the optimization of the state , taking an example of a magnetic vortex crystal state realized in itinerant magnets .
we show that the efficiency is maximized when the local heating temperature is tuned to be comparable to the characteristic energy scale of the ordered state . .
And you have already written the first three sentences of the full article: numerical simulation is one of the most powerful methods for searching thermal equilibrium states of the system .
it has elucidated numerous novel properties that one could hardly deal with analytically .
one of the standard techniques is the markov - chain monte carlo sampling on the basis of the metropolis algorithm , e.g. , the single - spin flip update used for classical spin systems ..
Please generate the next two sentences of the article | a common difficulty in such numerical simulations is that the state is often frozen into some configuration and hardly updated , especially when the system has a peculiar energy landscape with multiple local minima or almost flat energy dependence in the phase space .
for instance , in some classical spin systems , the spin configuration is frozen in a multiple - domain state , and hardly escapes from the metastable state by local spin - flip update . for avoiding such freezing problems , |
4,238 | Suppose that you have an abstract for a scientific paper: this paper is devoted to study the circumstances favourable to detect circumstellar and circumbinary planets in well detached binary - star - systems using eclipse timing variations ( etvs ) .
we investigated the dynamics of well detached binary star systems with a star separation from 0.5 to 3 au , to determine the probability of the detection of such variations with ground based telescopes and space telescopes ( like former missions corot and kepler and future space missions plato , tess and cheops ) .
for the chosen star separations both dynamical configurations ( circumstellar and circumbinary ) may be observable .
we performed numerical simulations by using the full three - body problem as dynamical model .
the dynamical stability and the etvs are investigated by computing etv maps for different masses of the secondary star and the exoplanet ( earth , neptune and jupiter size ) .
in addition we changed the planet s and binary s eccentricities .
we conclude that many amplitudes of etvs are large enough to detect exoplanets in binary star systems . as an application , we prepared statistics of the catalogue of exoplanets in binary star systems which we introduce in this article and compared the statistics with our parameter - space which we used for our calculations .
in addition to these statistics of the catalogue we enlarged them by the investigation of well detached binary star systems from several catalogues and discussed the possibility of further candidates .
[ firstpage ] methods : numerical catalogues planets and satellites : detection (stars ) : planetary systems ( stars):binaries : general stars : statistics .
And you have already written the first three sentences of the full article: the first extra solar planet was discovered in the early 1990s by @xcite . today
the statistics of the observations show that the architecture of our solar system seems to be unique compared with exoplanetary systems . at the moment we know about 2000 exoplanets in more than 1200 planetary systems , among them more than 100 exoplanets are in binary - star systems and two dozen are in multiple - star systems .
the data of all planets are collected in the exoplanet - catalogue maintained by j. schneider ; whereas the binary and multiple - star systems can be found separately in the catalogue of exoplanets in binary star systems maintained by r. schwarz , which we will also introduce in this paper . + approximately 70 percent of the main- and pre - main - sequence stars are members of binary or multiple star systems : 67 % for g - m star , e.g. @xcite ; and approximately 70 % for o - b stars ( e.g. @xcite , @xcite ).
Please generate the next two sentences of the article | . statistics of solar - type dwarfs were studied by @xcite with a distance - limited sample of 4847 targets .
a field population was found of about 54% for single stars , 33% binary stars , 8% triple systems , 4% for quadrupole systems , 1% for systems |
4,239 | Suppose that you have an abstract for a scientific paper: we study the decay width and cp asymmetry of the inclusive process @xmath0 ( g denotes gluon ) in the multi higgs doublet models with complex yukawa couplings , including next to leading qcd corrections .
we analyse the dependencies of the decay width and cp asymmetry on the scale @xmath1 and cp violating parameter @xmath2 .
we observe that there exist an enhancement in the decay width and cp asymmetry is at the order of @xmath3 . .
And you have already written the first three sentences of the full article: rare b decays are induced by flavor changing neutral currents ( fcnc ) at loop level
. therefore they are phenomenologically rich and provide a comprehensive information about the theoretical models and the existing free parameters .
the forthcoming experiments at slac , kek b - factories , hera - b and possible future accelerators stimulate the study of such decays since the large number of events can take place and various branching ratios , cp - violating asymmetries , polarization effects , etc ..
Please generate the next two sentences of the article | , can be measured @xcite . among b decay modes ,
inclusive @xmath0 is interesting since it is theoretically clean and sensitive to new physics beyond the sm , like two higgs doublet model ( 2hdm ) @xcite , minimal supersymmetric standard model ( mssm ) @xcite , etc . |
4,240 | Suppose that you have an abstract for a scientific paper: symmetry protected topological ( spt ) states are short - range entangled states with symmetry , which have symmetry protected gapless edge states around a gapped bulk .
recently , we proposed a systematic construction of spt phases in interacting bosonic systems , however it is not very clear what is the form of the low energy excitations on the gapless edge . in this paper , we answer this question for two dimensional bosonic spt phases with @xmath0 and @xmath1 symmetry . we find that while the low energy modes of the gapless edges are non - chiral , symmetry acts on them in a chiral way , i.e. acts on the right movers and the left movers differently . this special realization of symmetry
protects the gaplessness of the otherwise unstable edge states by prohibiting a direct scattering between the left and right movers .
moreover , understanding of the low energy effective theory leads to experimental predictions about the spt phases .
in particular , we find that _ all _ the 2d @xmath1 spt phases have _ even _ integer quantized hall conductance .
_ introduction _ a recent study shows that gapped quantum states belong to two classes : short - range entangled and long - range entangled.@xcite the long - range entanglement ( i.e. the topological order@xcite ) in the bulk of states is manifested in the existence of gapless edge modes or degenerate edge sectors .
the short - range entangled states are trivial and all belong to the same phase if there is no symmetry . however , with symmetry , even short - range entangled states can belong to different phases .
those phases are called symmetry protected topological ( spt ) phases . the symmetric short - range entanglement ( i.e. the spt order )
is also manifested in the existence of gapless edge modes around a gapped bulk if the symmetry is not broken .
for example , two and three dimensional topological insulators@xcite have a gapped insulating bulk but host gapless fermion modes with special spin configurations @xcite on the edge under....
And you have already written the first three sentences of the full article: in this section , we will briefly describe the group cohomology theory . as we are focusing on 2d spt phases
, we will be interested in the third cohomology group .
for a group @xmath2 , let @xmath56 be a g - module , which is an abelian group ( with multiplication operation ) on which @xmath2 acts compatibly with the multiplication operation ( the abelian group structure ) on @xmath56 : @xmath102 for the cases studied in this paper , @xmath56 is simply the @xmath1 group and @xmath32 an @xmath1 phase . the multiplication operation @xmath103 is the usual multiplication of the @xmath1 phases . the group action is trivial : @xmath104 , @xmath105 , @xmath106 ..
Please generate the next two sentences of the article | let @xmath107 be a function of @xmath108 group elements whose value is in the g - module @xmath56 .
in other words , @xmath109 . |
4,241 | Suppose that you have an abstract for a scientific paper: we present oxygen abundances derived from both the permitted and forbidden oxygen lines for 55 subgiants and giants with @xmath0}$ ] values between @xmath1 and solar with the goal of understanding the discrepancy in the derived abundances . a first attempt , using t@xmath2 values from photometric calibrations and surface gravities from luminosities , obtained agreement between the indicators for turn - off stars , but the disagreement was large for evolved stars .
we find that the difference in the oxygen abundances derived from the permitted and forbidden lines is most strongly affected by t@xmath2 , and we derive a new t@xmath2 scale based on forcing the two sets of lines to give the same oxygen abundances .
these new parameters , however , do not agree with other observables , such as theoretical isochrones or balmer - line profile based t@xmath2 determinations .
our analysis finds that one - dimensional , lte analyses ( with published nlte corrections for the permitted lines ) can not fully resolve the disagreement in the two indicators without adopting a temperature scale incompatible with other temperature indicators .
we also find no evidence of circumstellar emission in the forbidden lines , removing such emission as a possible cause for the discrepancy . .
And you have already written the first three sentences of the full article: oxygen is the third most common element in the universe .
it is copiously produced when massive stars explode as type ii supernova .
this distinguishes it from fe , which is also made in type ia sn , the accretion - induced explosions of white dwarfs ..
Please generate the next two sentences of the article | the [ o / fe ] ratio therefore reflects the mix of stars that have contributed to the enrichment of a system .
it has been used to diagnose the source of metals in x - ray gas in galaxies @xcite and in damped ly@xmath3 systems @xcite . |
4,242 | Suppose that you have an abstract for a scientific paper: a general two higgs doublet model ( 2hdm ) is adopted to study the signature of flavor changing neutral higgs ( fcnh ) decay @xmath0 , where @xmath1 could be a cp - even scalar ( @xmath2 ) or a cp - odd pseudoscalar ( @xmath3 ) .
measurement of the light 125 gev neutral higgs boson ( @xmath4 ) couplings at the large hadron collider ( lhc ) favor the decoupling limit or the alignment limit of a 2hdm , in which gauge boson and diagonal fermion couplings of @xmath4 approach standard model values . in such limit , fcnh couplings of @xmath4 are naturally suppressed by a small mixing parameter @xmath5 , while the off - diagonal couplings of heavier neutral scalars @xmath1 are sustained by @xmath6 .
we study physics background from dominant processes with realistic acceptance cuts and tagging efficiencies .
promising results are found for the lhc running at 13 or 14 tev collision energies . .
And you have already written the first three sentences of the full article: the standard model ( sm ) is very successful in explaining almost all experimental data to date , culminating in the recent discovery of the long awaited higgs boson at the cern large hadron collider ( lhc ) @xcite . in the sm
, all elementary particles acquire mass from a single higgs doublet that generates spontaneous electroweak symmetry breaking ( ewsb ) .
all charged fermions have their masses and yukawa couplings to the higgs boson as correlated but free parameters . furthermore , there are no flavor changing neutral currents ( fcnc ) mediated by gauge interactions , nor by higgs interactions ( fcnh ) , at the tree level.
Please generate the next two sentences of the article | . the most important goals of the lhc , at run 2 and beyond , are the study of higgs properties and the search for signals , direct or indirect , of new physics beyond the sm .
as the most massive particle ever discovered , the top quark might provide clues to better understand the mechanism of ewsb . a possible explanation for its heaviness could be provided by a special two higgs doublet model for the top quark ( t2hdm ) @xcite , where it is the only fermion that couples to a higgs doublet with a large vacuum expectation value ( vev ) . |
4,243 | Suppose that you have an abstract for a scientific paper: cross sections for the reaction were measured in hall c at thomas jefferson national accelerator facility ( jlab ) using the cebaf high - intensity , continous electron beam in order to determine the charged pion form factor .
data were taken for central four - momentum transfers ranging from @xmath0=0.60 to 2.45 gev@xmath1 at an invariant mass of the virtual photon - nucleon system of @xmath2=1.95 and 2.22 gev .
the measured cross sections were separated into the four structure functions , , , and .
the various parts of the experimental setup and the analysis steps are described in detail , including the calibrations and systematic studies , which were needed to obtain high precision results .
the different types of systematic uncertainties are also discussed .
the results for the separated cross sections as a function of the mandelstam variable @xmath3 at the different values of are presented .
some global features of the data are discussed , and the data are compared with the results of some model calculations for the reaction . .
And you have already written the first three sentences of the full article: a fundamental challenge in hadronic physics is trying to understand the structure of mesons and baryons in terms of their quark - gluon constituents , as given by the underlying theory of the strong interaction .
this theory is known as quantum chromodynamics ( qcd ) .
form factors of hadrons play an important role in this description , because they provide information about the internal structure of the hadron ..
Please generate the next two sentences of the article | one of the simplest hadronic systems available for study is the pion , whose valence structure is a bound state of a quark and an antiquark .
its electromagnetic structure is parameterized by a single form factor , 2 , which depends on @xmath4 , where @xmath5 is the four - momentum squared of the virtual photon . |
4,244 | Suppose that you have an abstract for a scientific paper: a fully covariant model for describing the electromagnetic decay of vector mesons , both in light and in heavy sectors , is presented .
the main ingredients of our approach are i ) an ansatz for the bethe - salpeter vertex for vector mesons , and ii ) a mandelstam - like formula for the electromagnetic decay constant .
the free parameters of our approach are fixed through a comparison with the transverse momentum distribution obtained within a light - front hamiltonian dynamics framework with constituent quarks .
preliminary results for both the decays constants and the probability of the valence component are shown .
= 11.6pt .
And you have already written the first three sentences of the full article: aim of this contribution is to present a fully covariant model for describing the electromagnetic ( em ) decay of vector mesons ( vm s ) , both in light and heavy sectors . to this end ,
a simple analytic form for the bethe - salpeter ( bs ) amplitude of vm s is adopted in order to perform without any further approximation the calculations of the decay constants . moreover , with such an ansatz one can easily evaluate the so - called transverse momentum distribution of a constituent inside the vm ( see de melo et al @xcite for the pion case ) , that plays an essential role for fixing the value of the parameters appearing in our approach , and in turn for including some non perturbative inputs in our analytical ansatz . a possible form of the bs amplitude for an interacting @xmath0 system with @xmath1 ,
can be written as follows _ ( k , p)=s(k , m_1 ) _ vm(k , k.
Please generate the next two sentences of the article | - p ) s(k - p , m_2 ) where @xmath2 is the dirac propagator of a constituent with mass @xmath3 , @xmath4 the four - momentum of a vm with mass @xmath5 , @xmath6 its polarization four - vector , @xmath7 the helicity , @xmath8 the dirac structure of the amplitude and @xmath9 the momentum dependence of the bs amplitude .
in particular , the adopted covariant form for the dirac structure is the familiar one ( transverse to @xmath4 ) , viz v^(p ) = m m+m_1+m_2 that in the limit of non interacting system leads to the melosh rotations for a @xmath10 system @xcite , as expected . |
4,245 | Suppose that you have an abstract for a scientific paper: the monster tower , also known as the semple tower , is a sequence of manifolds with distributions of interest to both differential and algebraic geometers .
each manifold is a projective bundle over the previous .
moreover , each level is a fiber compactified jet bundle equipped with an action of finite jets of the diffeomorphism group .
there is a correspondence between points in the tower and curves in the base manifold .
these points admit a stratification which can be encoded by a word called the rvt code . here
, we derive the spelling rules for these words in the case of a three dimensional base .
that is , we determine precisely which words are realized by points in the tower . to this end
, we study the incidence relations between certain subtowers , called baby monsters , and present a general method for determining the level at which each baby monster is born . here , we focus on the case where the base manifold is three dimensional , but all the methods presented generalize to bases of arbitrary dimension . .
And you have already written the first three sentences of the full article: the monster tower , also known as the semple tower , lies in the intersection of differential geometry , non - holonomic mechanics , singularity theory , and algebraic geometry .
cartan ( @xcite studied the diffeomorphism group action on jet spaces , which led to developments in the fields of goursat distributions and sub - riemannian geometry .
jean @xcite , luca and risler @xcite , li and respondek @xcite , pelletier and slayman @xcite , and others have studied models of various kinematic systems ( a car pulling @xmath0 trailers , motion of an articulated arm , @xmath0-bar systems ) ..
Please generate the next two sentences of the article | montgomery and zhitomirskii @xcite studied the relationship with curve singularities ; later , so did we @xcite . and
we discovered in @xcite that algebraic geometers have long studied these objects under different names . |
4,246 | Suppose that you have an abstract for a scientific paper: we show that quantum optical systems preserving the total number of excitations admit a simple classification of possible resonant transitions ( including effective ) , which can be classified by analizying the free hamiltonian and the corresponding integrals of motion .
quantum systems not preserving the total number of excitations do not admit such a simple classification , so that an explicit form of the effective hamiltonian is needed to specify the allowed resonances .
the structure of the resonant transitions essentially depends on the algebraic propereties of interacting subsystems . .
And you have already written the first three sentences of the full article: in a direct analogy with classical mechanics , composed systems in quantum optics ( which describe interaction between several subsystems ) can be divided into two classes : 1 ) systems which possess a necessary number of integrals of motion , so that , the classical counterpart is an integrable system ; 2 ) systems that do not admit a sufficient number of integrals of motions , so that , the classical counterpart is a non - integrable system caos . a quantum system can have basically two types of integrals of motion : a ) _ kinematic _ integrals , which do not depend on the kind of interaction between subsystems , as for instance , the total number of atoms ; b ) _ dynamic _ integrals which are related to the particular form of interaction between subsystems , as , for instance , a number of excitations preserved in some transitions between the energy levels of the subsystems .
typical for quantum optical systems dipole - like interactions between two subsystems ( @xmath0 and @xmath1 ) can be described with a generic multichannel hamiltonian of the following form:@xmath2where the two first terms represent the free hamiltonians of the subsystems , so that the frequencies @xmath3 , and the last term describes the interaction between them .
the operators @xmath4 , @xmath5 , @xmath6=0 $ ] , are usually elements of some deformed algebra @xcite , and in particular , satisfy the ladder commutation relations@xmath7 = \pm x_{\pm } ^{j},\hspace{0.1in}\left [ y_{0}^{j},y_{\pm } ^{j}\right ] = \pm y_{\pm } ^{j}. \label{escal}\ ] ] in the interaction hamiltonian there are two kinds of terms : of the form @xmath8 and @xmath9 it is easy to observe that in the rotating frame , that is , applying the following unitary transformation@xmath10 \right)\]]to the hamiltonian ( [ h1 ] ) , the _ counterrotating _ terms @xmath11 oscillate in time with a frequency @xmath12 and the _ rotating _.
Please generate the next two sentences of the article | terms @xmath13 oscillate with a frequency @xmath14 .
it is clear that under the condition @xmath15 the rotating term @xmath8 in ( [ h1 ] ) is approximately time independent ( and thus , can generate transitions with a probability of one between the energy levels of the system ) , meanwhile the counterrotating _ _ _ _ term , @xmath16 always oscillates rapidly in the rotating frame , and its temporal average is zero . by neglecting the counterrotating terms in the hamiltonian ( [ h1 ] ) , which is commonly called the rotating wave approximation ( rwa ) , we arrive at the hamiltonian@xmath17which admits several dynamic integrals of motion @xmath18 , generally not allowed in ( [ h1 ] ) . |
4,247 | Suppose that you have an abstract for a scientific paper: recent progress in the understanding of how externally driven magnetic reconnection evolves is organized in terms of parameter space diagrams .
these diagrams are constructed using four pivotal dimensionless parameters : the lundquist number @xmath0 , the magnetic prandtl number @xmath1 , the amplitude of the boundary perturbation @xmath2 , and the perturbation wave number @xmath3 .
this new representation highlights the parameters regions of a given system in which the magnetic reconnection process is expected to be distinguished by a specific evolution .
contrary to previously proposed phase diagrams , the diagrams introduced here take into account the dynamical evolution of the reconnection process and are able to predict slow or fast reconnection regimes for the same values of @xmath0 and @xmath1 , depending on the parameters that characterize the external drive , never considered so far .
these features are important to understand the onset and evolution of magnetic reconnection in diverse physical systems . .
And you have already written the first three sentences of the full article: magnetic reconnection is a process whereby the magnetic field line connectivity @xcite is modified due to the presence of a localized diffusion region .
this gives rise to a change in magnetic field line topology and a release of magnetic energy into kinetic and thermal energy .
reconnection of magnetic field lines is ubiquitous in laboratory , space and astrophysical plasmas , where it is believed to play a key role in many of the most striking and energetic phenomena ..
Please generate the next two sentences of the article | the most notable examples of such phenomena include sawtooth crashes @xcite and major disruptions in tokamak experiments @xcite , solar and stellar flares @xcite , coronal mass ejections @xcite , magnetospheric substorms @xcite , coronal heating @xcite , and high - energy emissions in pulsar wind nebulae , gamma - ray bursts and jets from active galactic nuclei @xcite .
an exhaustive understanding of how magnetic reconnection proceeds in various regimes is therefore essential to shed light on these phenomena . in recent years , for the purpose of organizing the current knowledge of the reconnection dynamics that is expected in a system with given plasma parameters , a particular form of phase diagrams have been developed @xcite . |
4,248 | Suppose that you have an abstract for a scientific paper: the significance of proposals that can predict different results for standard and bohmian quantum mechanics have been the subject of many discussions over the years . here , we suggest a particular experiment ( a two double - slit experiment ) and a special detection process , that we call selective detection , to distinguish between the two theories . using our suggested experiment , it is shown that the two theories predict different observable results at the individual level for a geometrically symmetric arrangement . however ,
their predictions are the same at the ensemble level . on the other hand
, we have shown that at the statistical level , if we use our selective detection , then either the predictions of the two theories differ or where standard quantum mechanics is silent or vague , bohmian quantum mechanics makes explicit predictions .
pacs number(s ) : 03.65.bz + .
And you have already written the first three sentences of the full article: according to the standard quantum mechanics ( sqm ) , the complete description of a system of particles is provided by its wavefunction .
the empirical predictions of sqm follow from a mathematical formalism which makes no use of the assumption that matter consists of particles pursuing definite tracks in space - time .
it follows that the results of the experiments designed to test the predictions of the theory , do not permit us to infer any statement regarding the particle not even its independent existence ..
Please generate the next two sentences of the article | but , in the bohmian quantum mechanics ( bqm ) , the additional element that is introduced apart from the wavefunction is the particle position , conceived in the classical sense as pursuing a definite continuous track in space - time [ 1 - 3 ] .
the detailed predictions made by this causal interpretation explains how the results of quantum experiments come about but it is claimed that they are not tested by them . in fact |
4,249 | Suppose that you have an abstract for a scientific paper: we present the software library ` libcreme ` which we have previously used to successfully calculate convex - roof entanglement measures of mixed quantum states appearing in realistic physical systems . evaluating
the amount of entanglement in such states is in general a non - trivial task requiring to solve a highly non - linear complex optimization problem .
the algorithms provided here are able to achieve to do this for a large and important class of entanglement measures .
the library is mostly written in the matlab programming language , but is fully compatible to the free and open - source octave platform .
some inefficient subroutines are written in c / c++ for better performance .
this manuscript discusses the most important theoretical concepts and workings of the algorithms , focussing on the actual implementation and usage within the library .
detailed examples in the end should make it easy for the user to apply ` libcreme ` to specific problems .
entanglement measure , convex roof * program summary * _ manuscript title : _ libcreme : an optimization library for evaluating convex - roof entanglement measures + _ authors : _ beat rthlisberger , jrg lehmann , daniel loss + _ program title : _ libcreme + _ journal reference : _
+ _ catalogue identifier : _
+ _ licensing provisions : _ gnu gpl version 3 + _ programming language : _ matlab / octave and c / c++ + _ operating system : _ all systems running matlab or octave + _ keywords : _ entanglement measure , convex roof + _ classification : _ 4.9 , 4.15 + _ nature of problem : _ + evaluate convex - roof entanglement measures .
this involves solving a non - linear ( unitary ) optimization problem .
+ _ solution method : _ + two algorithms are provided : a conjugate - gradient method using a differential - geometric approach and a quasi - newton method together with a mapping to euclidean space .
+ _ running time : _ + typically seconds to minutes for a density matrix of a few low - dimensional systems and a decent....
And you have already written the first three sentences of the full article: the role of non - local quantum correlations , more familiarly known as entanglement , in modern quantum theory can not be overstated @xcite . on the one hand , entanglement lies at the heart of quantum information theory @xcite , where it is a crucial ingredient to computation and communication schemes . on the other hand ,
it is intricately related to phenomena such as decoherence @xcite and quantum phase transitions in many - body systems @xcite .
one has come to realize that entanglement is also a resource that can for instance be purified , shared , and possibly irreversibly lost , and should therefore not only be detectable , but also quantifiable @xcite ..
Please generate the next two sentences of the article | one way of doing so is by virtue of entanglement measures @xcite .
these are mathematical functions mapping quantum states to the set of real numbers . |
4,250 | Suppose that you have an abstract for a scientific paper: we present simultaneous mappings of @xmath0 emission of @xmath1co , @xmath2co , and c@xmath3o molecules toward the whole disk ( @xmath4 or 20.8 kpc @xmath5 13.0 kpc ) of the nearby barred spiral galaxy ngc 2903 with the nobeyama radio observatory 45-m telescope at an effective angular resolution of @xmath6 ( or 870 pc ) .
we detected @xmath1co(@xmath0 ) emission over the disk of ngc 2903 .
in addition , significant @xmath2co(@xmath0 ) emission was found at the center and bar - ends , whereas we could not detect any significant c@xmath3o(@xmath0 ) emission . in order to improve the signal - to - noise ratio of co emission and to obtain accurate line ratios of @xmath1co(@xmath7)/@xmath1co(@xmath0 ) ( @xmath8 ) and @xmath2co(@xmath0)/@xmath1co(@xmath0 ) ( @xmath9 ) , we performed the stacking analysis for our @xmath1co(@xmath0 ) , @xmath2co(@xmath0 ) , and archival @xmath1co(@xmath7 ) spectra with velocity - axis alignment in nine representative regions of ngc 2903 .
we successfully obtained the stacked spectra of the three co lines , and could measure averaged @xmath8 and @xmath9 with high significance for all the regions .
we found that both @xmath8 and @xmath9 differ according to the regions , which reflects the difference in the physical properties of molecular gas ; i.e. , density ( @xmath10 ) and kinetic temperature ( @xmath11 ) .
we determined @xmath10 and @xmath11 using @xmath8 and @xmath9 based on the large velocity gradient approximation .
the derived @xmath10 ranges from @xmath12 @xmath13 ( in the bar , bar - ends , and spiral arms ) to 3700 @xmath13 ( at the center ) and the derived @xmath11 ranges from 10 k ( in the bar and spiral arms ) to 30 k ( at the center ) .
we examined the dependence of star formation efficiencies ( sfes ) on @xmath10 and @xmath11 , and found the positive correlation between sfe and @xmath10 with the correlation coefficient for the least - square power - law fit @xmath14 of 0.50 .
this suggests that molecular gas density governs the spatial variations in sfes . .
And you have already written the first three sentences of the full article: molecular gas is one of the essential components in galaxies because it is closely related to star formation , which is a fundamental process of galaxy evolution .
thus the observational study of molecular gas is indispensable to understand both star formation in galaxies and galaxy evolution .
however , the most abundant constituent in molecular gas , h@xmath15 , can not emit any electro - magnetic wave in cold molecular gas with typical temperature of @xmath16 10 k due to the lack of a permanent dipole moment . instead.
Please generate the next two sentences of the article | , rotational transition lines of @xmath1co , the second abundant molecule , have been used as a tracer of molecular gas .
for example , some extensive @xmath1co surveys of external galaxies , which consist of single pointings toward central regions and some mappings along the major axis , have been reported ( e.g. , @xcite ; @xcite ; @xcite ) . |
4,251 | Suppose that you have an abstract for a scientific paper: we develop a microscopic theory of the single impurity kondo effect on a metallic surface .
we calculate the hybridization energies for the anderson hamiltonian of a magnetic impurity interacting with surface and bulk states and show that , contrary to the kondo effect of an impurity in the bulk , the hybridization matrix elements are strongly dependent on the momentum around the fermi surface . furthermore , by calculating the tunneling conductance of a scanning tunneling microscope ( stm ) , we show that when the magnetic impurity is located at a surface the kondo effect can occur with equal strength between bulk and surface states .
we compare our results with recent experiments of co impurities in cu(111 ) and cu(100 ) surfaces and find good quantitative agreement . .
And you have already written the first three sentences of the full article: when a magnetic impurity is located in the bulk of a metal it undergoes a non - trivial many - body scattering with the electronic states at the fermi energy , @xmath0 , called the kondo effect @xcite . the bulk kondo effect ( to be contrasted with the surface kondo effect studied in this paper ) is one of the best studied problems in condensed matter physics and many different techniques from renormalization group @xcite to bethe ansatz @xcite have been used over the years .
the basic mechanism of the kondo effect is the magnetic screening of the impurity ( the formation of the kondo singlet ) at temperatures @xmath1 below the kondo temperature @xmath2 . above @xmath2
the magnetic impurity behaves paramagnetically but for @xmath3 a resonance is formed close to the fermi surface ..
Please generate the next two sentences of the article | the kondo effect is very important in modern condensed matter theory and appears in many different areas of research , from u and ce intermetallics ( heavy - fermions ) @xcite to quantum dots @xcite .
there is a wide variety of phenomena that can be described within the universality of the kondo problem . |
4,252 | Suppose that you have an abstract for a scientific paper: we introduce a new model of a stochastic sandpile on a graph @xmath0 containing a sink .
when unstable , a site sends one grain to each of its neighbours independently with probability @xmath1 $ ] . for @xmath2 ,
this coincides with the standard abelian sandpile model . in general , for @xmath3 , the set of recurrent configurations of this sandpile model is different from that of the abelian sandpile model .
we give a characterisation of this set in terms of orientations of the graph @xmath0 .
we also define the lacking polynomial @xmath4 as the generating function counting this set according to the number of grains , and show that this polynomial satisfies a recurrence which resembles that of the tutte polynomial . .
And you have already written the first three sentences of the full article: in this paper , we analyse a stochastic generalisation of the abelian sandpile model ( asm ) .
informally ( we provide a formal definition later ) , the asm operates on a graph where each vertex has a number of ` grains of sand ' on it . at every unit of time
, another grain of sand is added at a random vertex @xmath5 . if this causes the number of grains at @xmath5 to exceed its degree , @xmath5 topples , sending one grain to each of its neighbours ..
Please generate the next two sentences of the article | this may cause other vertices to topple , and we continue until the configuration is stable , i.e. no vertex can topple anymore .
a special vertex , the sink , can absorb any number of grains and never topples . |
4,253 | Suppose that you have an abstract for a scientific paper: we study the entanglement in the ground state of a chain of free spinless fermions with a single side - coupled impurity . we find a logarithmic scaling for the entanglement entropy of a segment neighboring the impurity .
the prefactor of the logarithm varies continuously and contains an impurity contribution described by a one - parameter function , while the contribution of the unmodified boundary enters additively .
the coefficient is found explicitly by pointing out similarities with other models involving interface defects .
the proposed formula gives excellent agreement with our numerical data .
if the segment has an open boundary , one finds a rapidly oscillating subleading term in the entropy that persists in the limit of large block sizes .
the particle number fluctuation inside the subsystem is also reported .
it is analogous with the expression for the entropy scaling , however with a simpler functional form for the coefficient . .
And you have already written the first three sentences of the full article: the entanglement properties of many - body systems have attracted considerable attention and have become the topic of a large number of studies in the last decade @xcite . in particular
, the study of a suitable measure of entanglement such as the entanglement entropy was triggered by the need to understand ground state properties that lead to the emergence of area laws @xcite .
this keyword refers to a rather generic property of ground states of bipartitioned systems in which the entropy @xmath0 of a subsystem scales as the number of contact points with the environment ..
Please generate the next two sentences of the article | the most notable and well understood counterexamples are represented by one - dimensional critical quantum systems with an underlying conformal symmetry where the area law is violated in the form of universal terms , scaling as the logarithm of the subsystem size @xcite . in the translationally invariant case
this can be written as @xmath1 with @xmath2 being the central charge of the conformal field theory ( cft ) and @xmath3 a non - universal constant . |
4,254 | Suppose that you have an abstract for a scientific paper: the multiple scattering of light in a gas of ultra cold atoms is responsible for many exciting features observed in magneto - optical traps including the collective behaviour forced by a coulomb like potential .
this field also induces plasma like phenomena in the cloud which allows the treatment of the system as a one component trapped plasma . with a fluid description and casting the thermodynamical behaviour in the form of a polytropic equation of state we investigate the equilibrium profiles of rotating clouds and its dependence on the experiment characteristics .
numerical solutions predict the formation of stable orbital modes both in rotating and non rotating clouds .
we also investigate the normal modes on such rotating systems .
the results obtained allow for the measurement of the equation of state for the cold gas . .
And you have already written the first three sentences of the full article: the celebrated laser cooling processes and magneto - optical traps ( mot ) @xcite have allowed the study of many exciting topics in atomic physics . among them , much interest was devoted to the study of bose - einstein condensates @xcite , which had a profound impart in our understanding of condensed matter .
apart from this , a new trend has recently begun that rekindled the interest on basic properties of mot physics .
this is related to the increasing number of astrophysical phenomena that we can simulate and study using ultra cold atomic clouds . in particular.
Please generate the next two sentences of the article | , we can refer to a new mechanism associated with the laser cooling process , which can lead to the formation of static and oscillating photon bubbles inside the gas @xcite .
photon bubbles have been considered in the astrophysical context @xcite where huge photon densities are required to have any significant impact on high energy particles . |
4,255 | Suppose that you have an abstract for a scientific paper: we study the longitudinal excitations of quantum antiferromagnets on a triangular lattice by a recently proposed microscopic many - body approach based on magnon - density waves .
we calculate the full longitudinal excitation spectra of the antiferromagnetic heisenberg model for a general spin quantum number in the isotropic limit .
similar to the square lattice model , we find that , at the center of the first hexagonal brillouin zone @xmath0 and at the magnetic ordering wavevectors @xmath1 $ ] , the excitation spectra become gapless in the thermodynamic limit , due to the slow , logarithmic divergence of the structure factor .
however , these longitudinal modes on two - dimensional models may be considered as quasi - gapped , as any finite - size effect or small anisotropy will induce a large energy gap , when compared with the counterpart of the transverse spin - wave excitations .
we also discuss a possible second longitudinal mode in the triangular lattice model due to the noncollinear nature of its magnetic order .
+ + pacs numbers : 75.10.jm , 75.30.ds , 75.50.ee .
And you have already written the first three sentences of the full article: anderson s spin - wave theory ( swt ) provides a good description for the low temperature properties of many two - dimensional ( 2d ) and three - dimensional ( 3d ) quantum antiferromagnetic systems on a bipartite lattice @xcite , including quantum corrections to the classical nel ground state with two alternating sublattices and the doublet transverse spin - wave excitations .
the quantum antiferromagnetic systems on a triangular lattice , however , are the prototypal system with the frustrated spin alignments in the classical picture and have been under intensive study over the last few decades for fundamentally different type of ground states @xcite .
it is now firmly established by various methods @xcite , including a swt based one three - sublattices @xcite , that the ground state of the antierromagnetic heisenberg model has the long - ranged noncollinear order of the @xmath2 magnetic three - sublattice structure with three transverse , gapless spin - wave excitations ..
Please generate the next two sentences of the article | most isotropic antiferromagnets in one - dimension ( 1d ) with low quantum spin numbers do not show nel - like long - ranged order in the ground state due to the strong quantum fluctuations .
the low - lying excitation states are also different from the 2d and 3d counterparts . in particular , by the exact solutions using the bethe ansatz @xcite , the low - lying excitation states of the 1d spin-1/2 heisenberg model have been shown corresponding to the spin-1/2 object ( spinons ) where the spin - wave - like excited states are the triplet states of spinons which always appear in pairs @xcite , contrast to the doublet excitation states by swt ; the excitation states of spin-1 heisenberg model for the linear chain , including the longitudinal one , have an excitation gap above the singlet ground state , first predicted by haldane @xcite . |
4,256 | Suppose that you have an abstract for a scientific paper: the purpose of this study is to carry out a thorough investigation of the changes in morphology of the red giant branch ( rgb ) of galactic globular clusters ( ggc ) as a function of metallicity , in the @xmath0 bands . to this aim ,
two key points are developed in the course of the analysis . *
( a ) * using our photometric @xmath0 database for galactic globular clusters ( the largest homogeneous data sample to date ; rosenberg et al .
@xcite ) _ we measure a complete set of metallicity indices _ , based on the morphology and position of the red - giant branch . in particular , we provide here the first calibration of the @xmath1 , @xmath2 and @xmath3 indices in the @xmath4 plane .
we show that our indices are internally consistent , and we calibrate each index in terms of metallicity , both on the zinn & west ( 1984 ) and the carretta & gratton ( 1997 ) scales .
our new calibrations of the @xmath5 , @xmath6 , @xmath7 and @xmath8 indices are consistent with existing relations . *
( b ) * using a grid of selected rgb fiducial points , _ we define a function in the @xmath9 $ ] space which is able to reproduce the whole set of ggc giant branches in terms of a single parameter _ ( the metallicity ) . as a first test , we show that the function is able to predict the correct trend of our observed indices with metallicity
. the usage of this function will improve the current determinations of metallicity and distances within the local group , since it allows to easily map @xmath10 coordinates into @xmath11,m_{i } $ ] ones . to this
aim the `` synthetic '' rgb distribution is generated both for the currently used lee et al .
( 1990 ) distance scale , and for the most recent results on the rr lyr distance scale . .
And you have already written the first three sentences of the full article: rrrrrrr & & & & + & & & & & & + 104 & 0.05 & 0.06 & -0.71 & -0.70 & -0.78 & 14.05 @xmath12 0.05 + 288 & 0.03 & 0.04 & -1.40 & -1.07 & -1.14 & 15.40 @xmath12 0.05 + 362 & 0.05 & 0.06 & -1.33 & -1.15 & -1.09 & 15.51 @xmath12 0.05 + 1261 & 0.01 & 0.01 & -1.32 & & -1.08 & 16.68 @xmath12 0.05 + 1851 & 0.02 & 0.03 & -1.23 & & -1.03 & 16.18 @xmath12 0.05 + 1904 & 0.01 & 0.01 & -1.67 & -1.37 & -1.37 & 16.15 @xmath12 0.05 + 3201 & 0.21 & 0.27 & -1.53 & -1.23 & -1.24 & 14.75 @xmath12 0.05 + 4590 & 0.04 & 0.05 & -2.11 & -1.99 & -2.00 & 15.75 @xmath12 0.10 + 4833 & 0.33 & 0.42 & -1.92 & -1.58 & -1.71 & 15.70 @xmath12 0.10 + 5272 & 0.01 & 0.01 & -1.66 & & -1.33 & 15.58 @xmath12 0.05 + 5466 & 0.00 & 0.00 & -2.22 & & -2.13 & 16.60 @xmath12 0.05 + 5897 & 0.08 & 0.10 & -1.93 & -1.59 & -1.73 & 16.30 @xmath12 0.10 + 5904 & 0.03 & 0.04 & -1.38 & -1.11 & -1.12 & 15.00 @xmath12 0.05 + 6093 & 0.18 & 0.23 & -1.75 & & -1.47 & 16.25 @xmath12 0.05 + 6171 & 0.33 & 0.42 & -1.09 & & -0.95 & 15.65 @xmath12 0.05 + 6205 & 0.02 & 0.03 & -1.63 & -1.39 & -1.33 & 14.95 @xmath12 0.10 + 6218 & 0.19 & 0.24 & -1.40 & & -1.14 & 14.70 @xmath12 0.10 + 6254 & 0.28 & 0.36 & -1.55 & -1.41 & -1.25 & 15.05 @xmath12 0.10 + 6341 & 0.02 & 0.03 & -2.24 & & -2.10 & 15.20 @xmath12 0.10 + 6352 & 0.21 & 0.27 & -0.50 & -0.64 & -0.70 & 15.25 @xmath12 0.05 + 6362 & 0.09 & 0.12 & -1.18 & -0.96 & -0.99 & 15.35 @xmath12 0.05 + 6397 & 0.18 & 0.23 & -1.94 & -1.82 & -1.76 & 12.95 @xmath12 0.10 + 6541 & 0.12 & 0.15 & -1.79 & & -1.53 & 15.40 @xmath12 0.10 + 6637 & 0.17 & 0.22 & -0.72 & & -0.78 & 15.95 @xmath12 0.05 + 6656 & 0.34 & 0.44 & -1.75 & & -1.41 & 14.25 @xmath12 0.10 + 6681 & 0.07 & 0.09 & -1.64 & & -1.35 & 15.70 @xmath12 0.05 + 6723 & 0.05 & 0.06 & -1.12 & & -0.96 & 15.45 @xmath12 0.05 + 6752 & 0.04 & 0.05 & -1.54 & -1.42 & -1.24 & 13.80 @xmath12 0.10 + 6779 & 0.20 & 0.26 & -1.94 & & -1.61 & 16.30 @xmath12 0.05 + 6809 & 0.07 & 0.09 & -1.80 & & -1.54 & 14.45 @xmath12 0.10 + 7078 & 0.09 & 0.12 & -2.13 & -2.12 & -2.02 & 15.90 @xmath12 0.05 + in very....
Please generate the next two sentences of the article | ( @xcite ; rhs97 ) based on spectroscopy of the caii infrared triplet .
the equivalent widths of the caii triplet have been calibrated by rhs97 on both the cg scale and the older zinn & west ( @xcite ; zw ) scale . |
4,257 | Suppose that you have an abstract for a scientific paper: we present far - infrared maps and spectroscopy for a number of deeply embedded protostellar objects ( cepe , hh211-mm , ic1396w , l1157 , l1211 , and rno15fir ) from data that we acquired with the iso instruments phot and lws .
several previously undetected deeply embedded sources are found in the vicinity of our targets .
we determine temperatures and luminosities of seven objects and locate them on a l@xmath0-t@xmath0 diagram the equivalent to a hertzsprung - russell diagram for protostars .
their masses and ages , according to their location on tracks taken from our evolutionary model , are derived .
l1211 and cepe appear to be intermediate mass objects which will reach final masses of about 3m@xmath1 , while the other sources are in or below the solar mass range .
the derived ages of 15000 to 30000yr are consistent with their current class0 state . a comparison of the luminosity of the associated outflows in the 10s(1 ) line of molecular hydrogen with the source properties ( bolometric luminosity , bolometric temperature , and envelope mass ) of 16 class0 sources shows no statistically significant correlations .
nevertheless , the data are consistent with a scheme in which the outflow strength and protostar evolve simultaneously .
we show that the relationship is partially disguised , however , by the local properties of the surrounding material , the extinction , and short - term flux variability .
[ firstpage ] stars : evolution stars : formation infrared : stars .
And you have already written the first three sentences of the full article: in the earliest stages of star formation the so - called class0 and class1 phases protostars are still deeply embedded in their parental molecular cloud cores .
this material absorbs almost all of the emitted radiation of the star in the optical and the near - infrared . the spectral energy distribution ( sed ) of class0 protostars peaks at about 100160@xmath2 m , the wavelength of the maximum of a modified blackbody at 3080k .
hence , direct observations of protostars have to be carried out in the far - infrared and in the ( sub-)mm wavelength range ..
Please generate the next two sentences of the article | sub - mm and millimeter observations of some of the sources investigated here have been obtained e.g. by lefloch et al .
@xcite , ladd & hodapp @xcite , chini et al . |
4,258 | Suppose that you have an abstract for a scientific paper: as a model for mesoscopic quantum systems in thermal contact , we consider a four - mode bose - hubbard model with two greatly differing tunneling rates . by a series of holstein - primakoff transformations we show that the low - frequency dynamics of this system consists in general of two slow josephson oscillations , rather than the single slow mode predicted by linear bogoliubov theory .
we identify the second slow josephson oscillation as a heat exchange mode analogous to second sound . .
And you have already written the first three sentences of the full article: experiments on mesoscopic quantum systems , and sophisticated numerical techniques for quantum many body theory , promise progress on deep questions about the relationship between microphysics and thermodynamics @xcite . we still require analytical theory , however , to clarify the questions .
for example , it should be well known that heat consists microscopically of energy held by degrees of freedom whose evolution is too rapid to perceive or control on macroscopic time scales @xcite .
this simple formulation is nonetheless surprising to many physicists , because heat is rarely discussed explicitly except in terms of ensembles ..
Please generate the next two sentences of the article | since the ensembles themselves are justified fundamentally as proxies for time averaging over rapid microscopic evolution , the role of time scale separation in defining heat is well established as an implicit assumption ; but it is underdeveloped as an explicit theory . investigating
the mesoscopic onset of thermodynamics will require fully developing this theory , because the applicability of ensembles is not obvious in small systems . |
4,259 | Suppose that you have an abstract for a scientific paper: the photoluminescence polarizations of ( in , ga)as / gaas quantum dots annealed at different temperatures are studied as a function of external magnetic field ( hanle curves ) . in these dependencies ,
remarkable resonant features appear due to all - optical nuclear magnetic resonances ( nmr ) for optical excitation with modulated circular polarization .
application of an additional radio - frequency field synchronously with the polarization modulation strongly modifies the nmr features .
the resonances can be related to transitions between different nuclear spin states split by the strain - induced gradient of the crystal field and by the externally applied magnetic field .
a theoretical model is developed to simulate quadrupole and zeeman splittings of the nuclear spins in a strained quantum dot .
comparison with the experiment allows us to uniquely identify the observed resonances .
the large broadening of the nmr resonances is attributed to variations of the quadrupole splitting within the quantum dot volume , which is well described by the model .
2aexperimentelle physik 2 , technische universitt dortmund , d-44221 dortmund , germany .
And you have already written the first three sentences of the full article: nuclear magnetic resonance ( nmr ) is based on the resonant absorption of radio frequency ( rf ) electromagnetic radiation by nuclear spin - split states by a magnetic field .
the absorption of rf field is limited by small differences of the populations of the nuclear - spin states in thermodynamic equilibrium .
therefore nmr requires probing of a macroscopically large number of nuclei ( @xmath0 ) @xcite ..
Please generate the next two sentences of the article | the nmr detection sensitivity can be greatly improved by preparing a nuclear - spin state with degree of polarization higher than the thermodynamic equilibrium value at a given magnetic field @xcite .
additional improvement is achieved by using optical methods to detect the state of the nuclear - spin system @xcite . |
4,260 | Suppose that you have an abstract for a scientific paper: this proceeding is based on a talk prepared for the xiv marcel grossmann meeting .
we review some results on causal set inspired non - local theories as well as work in progress concerning their phenomenology . .
And you have already written the first three sentences of the full article: quantizing gravity and/or the quantum nature of spacetime have been one of the central themes in theoretical physics in the last century .
the two pillars of modern physics , i.e. general relativity and quantum theory are reluctant to be reconciled despite many efforts . in spite of many theoretical advancements the field of quantum gravity ( qg ) still lacks contact with observations and experiments .
however , in recent years the field of quantum gravity phenomenology has started to attract the interest of the community . since to date.
Please generate the next two sentences of the article | we do not have a fully working quantum gravity model , but a plethora of models each with nice features and drawbacks , we should bet on common features shared by different models .
one of the recurring features in models of qg is the idea that spacetime may be fundamentally discrete . |
4,261 | Suppose that you have an abstract for a scientific paper: the proper incorporation of spin effects in @xmath0 lepton decays is often of importance . in present work the case of the @xmath1 production mechanism is studied in detail . as an example , the effects due to the spin correlations on the potential for the minimal supersymmetric standard model ( mssm ) higgs boson(s ) searches in the @xmath2 decay channel at the large hadron collider ( lhc ) are discussed . for these processes ,
the standard model @xmath3-pair production is a dominant background .
the spin effects in high energy physics reactions , can be implemented up to certain approximation , independently of the algorithm and matrix elements used by the production program .
information stored on every generated event can be sufficient .
the algorithm based on such approximation is documented .
question of the theoretical uncertaintity is partly discussed . *
tpju 2/2001 * + * t. pierzchaa@xmath4 , e. richter - was@xmath5 , z.was@xmath6 and m. worek@xmath4 * @xmath7_institute of physics , university of silesia + uniwersytecka 4 , 40 - 007 katowice , poland
_ + @xmath8 _ institute of computer science , jagellonian university + nawojki 11 , 30 - 072 cracow , poland _ + @xmath9_cern , ppe , 1211 geneva 23 , switzerland
_ + @xmath10_institute of nuclear physics + kawiory 26a , 30 - 055 cracow , poland _
+ @xmath11_cern , theory division , 1211 geneva 23 , switzerland
_ _ acta physica polonica _ * b 32 * ( 2001 ) 1277 * january 2001 * .
And you have already written the first three sentences of the full article: 0.3 cm in a study of `` discovery potential '' and data analysis of present high energy experiments the problems of precise predictions including , simultaneously , signal signatures of the new ( or studied ) physics , backgrounds , as well as all detector related effects should be analysed .
it is generally believed that a monte carlo simulation of the full chain from the beam collision to detector response is the most convenient technique to address such question .
in general it is indispensable to divide monte carlo simulation into separate blocks : physics event generation and detector response ..
Please generate the next two sentences of the article | later event generation can be divided further into parts , describing for example production and decay of the intermediate states . in the present paper
we will concentrate on the particular class of the processes involving polarised @xmath0 leptons . |
4,262 | Suppose that you have an abstract for a scientific paper: to help understand the effects of galaxy interactions on star formation , we analyze spitzer infrared and galex ultraviolet images of the interacting galaxy pair arp 82 ( ngc 2535/6 ) , and compare to a numerical simulation of the interaction .
we investigate the uv and ir properties of several star forming regions ( clumps ) . using the fuv / nuv colors of the clumps
we constrain the ages .
the 8 @xmath0 m and 24 @xmath0 m luminosities are used to estimate the far - infrared luminosities and the star formation rates of the clumps .
we investigate possible gradients in the uv and ir colors .
see smith et al .
( 2006a , b ) for global results on our entire interacting sample . .
And you have already written the first three sentences of the full article: we are investigating whether or not interacting but not yet merging galaxies have heightened star formation properties . in our spitzer spirals , bridges , and tails interacting galaxy study ( @xcite ) ,
we have compiled a sample of interacting galaxies selected from the arp atlas of peculiar galaxies @xcite .
we have previously presented a detailed study of one of these galaxies , arp 107 , in @xcite . in the current proceeding.
Please generate the next two sentences of the article | we investigate a second system , the interacting pair arp 82 ( ngc 2535/6 ) @xcite .
we have obtained uv , visible , and ir images of arp 82 from galex , sara , and spitzer telescopes respectively . |
4,263 | Suppose that you have an abstract for a scientific paper: the zero temperature properties of the generalized bose - hubbard model including three - body interactions are studied on a mean - field level .
we obtain analytical results using the so - called perturbative mean - field method and more detailed numerical results using the gutzwiller product state variational ansatz .
these two approaches yield equivalent results which compare well on a qualitative level with recent exact results obtained in the literature . .
And you have already written the first three sentences of the full article: the superfluid ( sf ) to mott - insulator ( mi ) transition of interacting bosonic particles on a lattice is a paradigmatic example of a quantum phase transition , introduced by fisher @xcite .
the realization in a seminal paper by jaksch @xcite that the bose - hubbard ( bh ) model can describe the dynamics of a system of ultra - cold atoms trapped in an optical lattice sparked interest in the experimental realization of this model which culminated in the successful break - through experiment by the munich group @xcite .
rapid experimental progress in the experimental atomic and molecular physics community is leading to the successful simulation of various interacting models of both boson and fermion many - body systems using trapped atoms and molecules @xcite . in step with these.
Please generate the next two sentences of the article | , various extensions of standard bh model have been vigorously studied theoretically @xcite .
a particularly interesting class of such models take into account not only two- but also three - body local interactions . |
4,264 | Suppose that you have an abstract for a scientific paper: improved terrestrial experiment to test the equivalence principle for rotating extended bodies is presented , and a new upper limit for the violation of the equivalence principle is obtained at the level of 1.6@xmath010@xmath1 , which is limited by the friction of the rotating gyroscope .
it means the spin - gravity interaction between the extended bodies has not been observed at this level . .
And you have already written the first three sentences of the full article: the equivalence principle ( ep ) , as one of the fundamental hypotheses of einstein s general relativity , has been tested by many experiments , including torsion balance scheme @xcite and free - fall one r5,r6,r7 .
lunar laser ranging from the earth to the moon has provided up to now the most accurate test of the ep to 5@xmath210@xmath3r8 .
recently , some different tests of ep for gravitational self - energy and spin - polarized macroscopic objects have been reported @xcite . however , in all of the experiments including the satellite test of the equivalence principle ( step ) and the galileo galilei ( gg ) space projects as well as the microscope space mission @xcite , the test masses are all non - rotating ..
Please generate the next two sentences of the article | it is well known that spin - interactions of elementary particles , spin - orbit coupling and spin - spin coupling , have been studied in both theory and experiment .
furthermore , the spin - gravitational couplings , i.e. the spin - gravitoelectric coupling and the spin - gravitomagnetic coupling , and the spin - rotation coupling between intrinsic spins have been also investigated for a long time @xcite . over the last few years |
4,265 | Suppose that you have an abstract for a scientific paper: bianchi type v perfect fluid cosmological models are investigated with cosmological term @xmath0 varying with time . using a generation technique ( camci _ et al . _ , 2001 ) , it is shown that the einstein s field equations are solvable for any arbitrary cosmic scale function .
solutions for particular forms of cosmic scale functions are also obtained .
the cosmological constant is found to be decreasing function of time , which is supported by results from recent type ia supernovae observations .
some physical aspects of the models are also discussed . .
And you have already written the first three sentences of the full article: the study of bianchi type v cosmological models create more interest as these models contain isotropic special cases and permit arbitrary small anisotropy levels at some instant of cosmic time .
this property makes them suitable as model of our universe . the homogeneous and isotropic friedman - robertson - walker ( frw ) cosmological models , which are used to describe standard cosmological models , are particular case of bianchi type i , v and ix universes , according to whether the constant curvature of the physical three - space , @xmath1 = constant , is zero , negative or positive .
these models will be interesting to construct cosmological models of the types which are of class one ..
Please generate the next two sentences of the article | present cosmology is based on the frw model which is completely homogeneous and isotropic .
this is in agreement with observational data about the large scale structure of the universe . |
4,266 | Suppose that you have an abstract for a scientific paper: we calculate the decay rate of light scalar mesons , using a diquark chiral effective theory , recently proposed to describe exotic hadrons . in the effective theory
the light scalar mesons are postulated to be bound states of diquark and anti - diquark .
we find our results are in good agreement with experimental data .
the axial couplings of diquarks with pions and kaons are found to be quite small and the perturbation is reliable .
it shows that the diquark picture captures the correct physics of light scalar mesons . .
And you have already written the first three sentences of the full article: recent discovery of exotic baryons @xcite revived the interest in hadron spectroscopy , especially that of exotic hadrons . among several models for exotic baryons ,
promising one is the diquark model @xcite , which assumes a strong correlation of two quarks in the color antitriplet channel . in the jaffe - wilczek ( jw )
diquark model @xcite , the exotic baryons are bound states of two scalar diquarks and one antiquark ..
Please generate the next two sentences of the article | the salient features of jw model are the occurrence of low - dimensional multiplets and small mass difference among the members in the multiplet , which were soon supported by the na49 experiment @xcite .
furthermore , the extremely narrow decay width of exotic baryons was naturally explained in the diquark picture of exotic baryons , where the decay process is suppressed by tunnelling among two diquarks @xcite . as the existence of hadrons containing quarks |
4,267 | Suppose that you have an abstract for a scientific paper: phase transitions of the mixed spin-1/2 and spin-@xmath0 ( @xmath1 ) ising model on a three - dimensional ( 3d ) decorated lattice with a layered magnetic structure are investigated within the framework of a precise mapping relationship to the simple spin-1/2 ising model on the tetragonal lattice .
this mapping correspondence yields for the layered ising model of mixed spins plausible results either by adopting the conjectured solution for the spin-1/2 ising model on the orthorhombic lattice [ z .- d .
zhang , philos . mag .
87 ( 2007 ) 5309 - 5419 ] or by performing extensive monte carlo simulations for the corresponding spin-1/2 ising model on the tetragonal lattice .
it is shown that the critical behaviour markedly depends on a relative strength of axial zero - field splitting parameter , inter- and intra - layer interactions .
the striking spontaneous order captured to the quasi-1d spin system is found in a restricted region of interaction parameters , where the zero - field splitting parameter forces all integer - valued decorating spins towards their non - magnetic spin state . , , and ising model , decoration - iteration transformation , monte carlo simulations , phase transitions 05.50.+q , 05.70.jk , 64.60.cn , 75.10.hk , 75.10.-b , 75.30.kz , 75.40.cx .
And you have already written the first three sentences of the full article: phase transitions and critical phenomena of rigorously solvable interacting many - particle systems are much sought after in the modern equilibrium statistical mechanics as they offer valuable insight into a cooperative nature of phase changes @xcite . beside this
, the usefulness of mathematically tractable models can also be viewed in providing guidance on a reliability of various approximative techniques , which are often needed for treating more complicated models that preclude exact analytical treatment . _
decorated planar ising models _ , which can be constructed by adding one or more spins on bonds of some original lattice , belong to the simplest mathematically tractable lattice - statistical models ( see ref ..
Please generate the next two sentences of the article | @xcite and references cited therein ) .
the main advantage of decorated ising models consists in a relative simple way of obtaining their exact solutions . as a matter of fact |
4,268 | Suppose that you have an abstract for a scientific paper: in this paper we specifically studied one aspect of foreground primordial matter density perturbations : the relative gravitational time delay between a pair of light paths converging towards an observer and originating from two points on the last scattering surface separated by the physical scale of an acoustic oscillation .
it is found that time delay biases the size of acoustic oscillations _ systematically _ towards smaller angles , or larger harmonic numbers @xmath0 , i.e. the mean geometry as revealed by cmb light becomes that of an open universe if @xmath1 . since the effect is second order , its standard deviation @xmath2 where @xmath3 is the normalization of the primordial matter spectrum @xmath4 , the consequence is too numerically feeble to warrant a re - interpretion of wmap data .
if , however , this normalization were increased to @xmath5 which is still well within the perturbation limit , the shift in the positions of the acoustic peaks would have been substantial enough to implicate inflationary @xmath6cdm cosmology .
thus @xmath7 is not the only parameter ( and by deduction inflation can not be the only mechanism ) of relevance to the understanding of _ observed _ large scale geometry .
the physics that explains why @xmath8 is so small also plays a crucial role , but since this is a separate issue independent of inflation , might it be less artificial to look for an alternative solution to the flatness problem altogether ? .
And you have already written the first three sentences of the full article: among the so - called ` secondary ' physical mechanisms that re - process the cmb anisotropy , such as gravitational lensing , time delay , and the sunyaev - zeldovich effect , time delay by foreground inhomogeneities in the matter distribution appears to be investigated least . in the recent period a detailed treatment of the problem
was provided by hu & cooray ( 2001 , hereafter hc01 ) , although the general framework for calculating gravitational perturbation effects on the cmb as published in the review of cmb lensing by lewis & challinor ( 2006 ) could also be employed to carry the study further .
in hc01 the authors found an infra - red logarithmic divergence in the variance of the _ absolute _ ( or total ) time delay along a randomly chosen direction to the lss ..
Please generate the next two sentences of the article | they ` renormalized ' this infinity by subtracting the contribution from the ` monopole ' term of the matter power spectrum , corresponding to the removal of a constant uniformly across the sky .
nevertheless , the remaining ( finite ) quantity still carries the divergence trend . |
4,269 | Suppose that you have an abstract for a scientific paper: a coarse grained description of a two - dimensional prey - predator system is given in terms of a 3-state lattice model containing two control parameters : the spreading rates of preys and predators .
the properties of the model are investigated by dynamical mean - field approximations and extensive numerical simulations .
it is shown that the stationary state phase diagram is divided into two phases : a pure prey phase and a coexistence phase of preys and predators in which temporal and spatial oscillations can be present .
the different type of phase transitions occuring at the boundary of the prey absorbing phase , as well as the crossover phenomena occuring between the oscillatory and non - oscillatory domains of the coexistence phase are studied .
the importance of finite size effects are discussed and scaling relations between different quantities are established .
finally , physical arguments , based on the spatial structure of the model , are given to explain the underlying mechanism leading to oscillations .
= 10000 2 .
And you have already written the first three sentences of the full article: the dynamics of interacting species has attracted a lot of attention since the pioneering works of lotka @xcite and volterra @xcite . in their independent studies
, they showed that simple prey - predator models may exhibit limit cycles during which the populations of both species have periodic oscillations in time .
however , this behavior depends strongly on the initial state , and it is not robust to the addition of more general non - linearities or to the presence of more than two interacting species @xcite . in many cases the system reaches a simple steady - state ..
Please generate the next two sentences of the article | a better understanding of the properties of such oscillations is clearly desirable , as such population cycles are often observed in ecological systems and the underlying causes remain a long - standing open question @xcite .
one of the best documented example concerns the canadian lynx population . |
4,270 | Suppose that you have an abstract for a scientific paper: software package for monte - carlo simulation of @xmath0 exclusive annihilation channels written in the c++ language for linux / solaris platforms has been developed .
it incorporates matrix elements for several mechanisms of multipion production in a model of consequent two and three - body resonance decays .
possible charge states of intermediate and final particles are accounted automatically under the assumption of isospin conservation .
interference effects can be taken into acccount .
package structure allows adding new matrix elements written in a gauge - invariant form .
= 14.5pt .
And you have already written the first three sentences of the full article: simulation of hadron production at low energies ( @xmath1 gev ) is relevant for various physical problems . as the cross - section in this region
is considered to be saturated with intermediate resonances , it is possible to study the properties of these resonances through mass , momentum and angular distributions .
simulation of different channels allows one to better account for selection rules and interference effects ..
Please generate the next two sentences of the article | in particular , the problem of measuring r ( total cross - section of @xmath0 annihilation into hadrons ) is a crucial information for contemporary high energy physics , especially for the @xmath2 problem @xcite . at low energies this value
can only be obtained from an experiment . |
4,271 | Suppose that you have an abstract for a scientific paper: analytical and numerical modelling of the nonlinear interaction of shear wave with a frictional interface is presented .
the system studied is composed of two homogeneous and isotropic elastic solids , brought into frictional contact by remote normal compression . a shear wave , either time harmonic or a narrow band pulse , is incident normal to the interface and propagates through the contact .
two friction laws are considered and their influence on interface behavior is investigated : coulomb s law with a constant friction coefficient and a slip - weakening friction law which involves static and dynamic friction coefficients . the relationship between the nonlinear harmonics and the dissipated energy , and their dependence on the contact dynamics ( friction law , sliding and tangential stress ) and on the normal contact stress
are examined in detail .
the analytical and numerical results indicate universal type laws for the amplitude of the higher harmonics and for the dissipated energy , properly non - dimensionalized in terms of the pre - stress , the friction coefficient and the incident amplitude .
the results suggest that measurements of higher harmonics can be used to quantify friction and dissipation effects of a sliding interface . .
And you have already written the first three sentences of the full article: the detection of contacting interfaces which can slide or open under applied load is a difficult task but one that is relevant in many technologies .
examples include closed cracks or defects , glued bondings , and partially delaminated material interfaces .
ultrasonic methods based on linear wave scattering are efficient for detecting defects and characterizing material elasticity , but are less sensitive to closed cracks and contacting interfaces . using the nonlinear behavior of these defects , nonlinear ultrasonic techniques such as nonlinear resonance @xcite , sub- and higher - harmonic generation @xcite , and frequency - modulation @xcite have been shown to be sensitive to micro - cracks or closed cracks . for an overview of nonlinear acoustics applications see @xcite ..
Please generate the next two sentences of the article | when an ultrasonic wave with large enough amplitude is incident on a contact with a frictional interface ( e.g. closed cracks ) , higher harmonics appear in the frequency spectrum of transmitted and reflected waves .
this effect , called contact acoustic nonlinearity ( can ) @xcite , is of increasing interest for characterization of closed cracks or imperfectly bonded interfaces @xcite . |
4,272 | Suppose that you have an abstract for a scientific paper: we study the well pronounced moreton wave that occurred in association with the x17.2 flare / cme event of october 28 , 2003 .
this moreton wave is striking for its global propagation and two separate wave centers , which implies that two waves were launched simultaneously .
the mean velocity of the moreton wave , tracked within different sectors of propagation direction , lies in the range of @xmath0 km s@xmath1 with two sectors showing wave deceleration .
the perturbation profile analysis of the wave indicates amplitude growth followed by amplitude weakening and broadening of the perturbation profile , which is consistent with a disturbance first driven and then evolving into a freely propagating wave .
the eit wavefront is found to lie on the same kinematical curve as the moreton wavefronts indicating that both are different signatures of the same physical process .
bipolar coronal dimmings are observed on the same opposite east - west edges of the active region as the moreton wave ignition centers .
the radio type ii source , which is co - spatially located with the first wave front , indicates that the wave was launched from an extended source region ( @xmath2 mm ) .
these findings suggest that the moreton wave is initiated by the cme expanding flanks . .
And you have already written the first three sentences of the full article: large - scale , large - amplitude disturbances propagating in the solar atmosphere were first recorded by @xcite and @xcite in the chromospheric h@xmath3 spectral line ; therefore called `` moreton waves '' .
typical velocities are in the range @xmath4 km s@xmath1 , and the angular extents are @xmath5 ( e.g. * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | since there is no chromospheric wave mode which can propagate at such high speeds , moreton waves were interpreted as the intersection line of an expanding , coronal fast - mode shock wave and the chromosphere which is compressed and pushed downward by the increased pressure behind the coronal shockfront @xcite .
they occur in association with major flare / cme events and type ii bursts @xcite , the latter being a direct signature of coronal shock waves . |
4,273 | Suppose that you have an abstract for a scientific paper: many of the conditions that are necessary for starbursts appear to be important in the triggering of qsos . however , it is still debatable whether starbursts are ubiquitously present in galaxies harboring qsos . in this paper
we review our current knowledge from observations of the role of starbursts in different types of qsos .
post - starburst stellar populations are potentially present in the majority of qso hosts .
qsos with far - infrared colors similar to those of ultraluminous infrared galaxies invariably reside in merging galaxies that have interaction - induced starbursts of a few hundred myr or less .
similar , but dramatically more luminous post - starburst populations are found in the recently discovered class of qsos known as post - starburst qsos , or q+a s . both of these classes , however , comprise only a small fraction ( @xmath0% ) of the total qso population .
the so - called `` red '' qsos generally suffer from strong extinction at optical wavelengths , making them ideal candidates for the study of hosts .
their stellar populations typically show a post - starburst component as well , though with a larger range of ages .
finally , optical `` classical '' qso hosts show traces of major star formation episodes ( typically involving @xmath110% of the mass of the stellar component ) in the more distant past ( 1 - 2 gyr ) . these starbursts appear to be linked to past merger events .
it remains to be determined whether these mergers were also responsible for triggering the qso activity that we observe today .
quasars : general , galaxies : interactions , galaxies : starburst 98.54.aj , 98.54.ep , 98.62.lv , 98.65.fz .
And you have already written the first three sentences of the full article: the relationship between mergers , starbursts , and active galactic nuclei ( agn ) has long since been the subject of vigourous research .
it is clear that at least some of the ingredients necessary to trigger starbursts are also necessary to trigger agn : both phenomena require fuel , and both require that this fuel be somehow displaced from one point to another , whether to replenish the material in the accretion disk , or to compress it resulting in enhanced star formation .
there is also evidence that mergers are important to both phenomena , although the precise role that they play is still debatable ..
Please generate the next two sentences of the article | the high incidence of mergers in starburst galaxies ( * ? ? ? * and references therein ) might indicate that mergers are indeed necessary to trigger massive starbursts , but they are not sufficient , since mergers often result in only moderately enhanced star formation ( e.g. , * ? ? ? * ) .
mergers have , on the other hand , only been shown to be required to trigger nuclear activity in far - infrared ( fir ) loud qsos @xcite , and are certainly not sufficient , as can be seen from the relatively low incidence of agn in any catalog of interacting galaxies . |
4,274 | Suppose that you have an abstract for a scientific paper: we report deep evn and emerlin observations of the type ia sn 2014j in the nearby galaxy m 82 .
our observations represent , together with jvla observations of sne 2011fe and 2014j , the most sensitive radio studies of type ia sne ever . by combining data and a proper modeling of the radio emission , we constrain the mass - loss rate from the progenitor system of sn 2014j to @xmath0 ( for a wind speed of @xmath1 ) . if the medium around the supernova is uniform , then @xmath2 , which is the most stringent limit for the ( uniform ) density around a type ia sn .
our deep upper limits favor a double - degenerate ( dd ) scenario involving two wd stars for the progenitor system of sn 2014j , as such systems have less circumstellar gas than our upper limits .
by contrast , most single - degenerate ( sd ) scenarios , i.e. , the wide family of progenitor systems where a red giant , main - sequence , or sub - giant star donates mass to a exploding wd , are ruled out by our observations ( for a wind speed of @xmath1 ) and @xmath3 , for the @xmath4 wind and constant density cases , respectively .
as these limits are less constraining than ours , the findings by @xcite do not alter our conclusions .
the x - ray results are , however , important to rule out free - free and synchrotron self - absorption as a reason for the radio non - detections . ] .
our estimates on the limits to the gas density surrounding sn2011fe , using the flux density limits from @xcite , agree well with their results .
although we discuss possibilities for a sd scenario to pass observational tests , as well as uncertainties in the modeling of the radio emission , the evidence from sne 2011fe and 2014j points in the direction of a dd scenario for both . .
And you have already written the first three sentences of the full article: type ia supernovae ( sne ) are the end - products of white dwarfs with a mass approaching the chandrasekhar limit , which results in a thermonuclear explosion of the star .
in addition to their use as cosmological distance indicators ( e.g. , * ? ? ? * ; * ? ? ?
* ) , type ia sne ( henceforth sne ia ) are a major contributor to the chemical evolution of galaxies ..
Please generate the next two sentences of the article | it is therefore unfortunate that we do not yet know what makes a sn ia .
this lack of knowledge makes it difficult to gain a physical understanding of the explosions , so that we can model possible evolution , which compromises their use as distance indicators . |
4,275 | Suppose that you have an abstract for a scientific paper: one of the most important questions regarding the progenitor systems of type ia supernovae ( sne ia ) is whether mergers of two white dwarfs can lead to explosions that reproduce observations of normal events . here
we present a fully three - dimensional simulation of a violent merger of two carbon - oxygen white dwarfs with masses of @xmath0 and @xmath1 combining very high resolution and exact initial conditions .
a well - tested combination of codes is used to study the system .
we start with the dynamical inspiral phase and follow the subsequent thermonuclear explosion under the plausible assumption that a detonation forms in the process of merging .
we then perform detailed nucleosynthesis calculations and radiative transfer simulations to predict synthetic observables from the homologously expanding supernova ejecta .
we find that synthetic color lightcurves of our merger , which produces about @xmath2 of @xmath3 , show good agreement with those observed for normal sne ia in all wave bands from u to k. line velocities in synthetic spectra around maximum light also agree well with observations .
we conclude , that violent mergers of massive white dwarfs can closely resemble normal sne ia .
therefore , depending on the number of such massive systems available these mergers may contribute at least a small fraction to the observed population of normal sne ia . .
And you have already written the first three sentences of the full article: despite many years of dedicated research , the progenitor systems and explosion mechanisms of sne ia remain unclear .
it is generally accepted that sne ia originate from thermonuclear explosions of massive carbon - oxygen white dwarfs in binary systems . depending on the nature of the companion star , two different progenitor systems have been proposed . in the _ single degenerate _
scenario @xcite a carbon - oxygen white dwarf accretes from a non - degenerate companion star until it reaches the chandrasekhar - mass and explodes ( but note that an explosion before reaching the chandrasekhar mass may also be possible , e.g. * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
in contrast , in the _ double degenerate _ |
4,276 | Suppose that you have an abstract for a scientific paper: we study coherence in a cold atom single photon switch where the gate photon is stored in a rydberg spinwave . with a combined field
theoretical and quantum jump approach and by employing a simple model description we investigate systematically how the coherence of the rydberg spinwave is affected by scattering of incoming photons . with large - scale numerical calculations
we show how coherence becomes increasingly protected with growing interatomic interaction strength . for the strongly interacting limit
we derive analytical expressions for the spinwave fidelity as a function of the optical depth and bandwidth of the incoming photon . .
And you have already written the first three sentences of the full article: cold gases of rydberg atoms are currently receiving a growing attention in the communities of quantum optics @xcite , quantum information @xcite , and many - body physics @xcite .
this is rooted in the fact that they offer strong and long - ranged interactions and at the same time grant long coherent lifetimes
. currently , considerable efforts are devoted to developing all - optical quantum information protocols @xcite with the rydberg - atom - mediated interaction between individual photons @xcite ..
Please generate the next two sentences of the article | fundamentally important optical devices that operate on the single photon level , such as phase shifters @xcite , switches @xcite and transistors @xcite , have been demonstrated experimentally in rydberg gases .
single photon switchs might form a central building block of an all - optical quantum information processor @xcite . |
4,277 | Suppose that you have an abstract for a scientific paper: in the simplest variant of the model of collective decision making in the stochastic environment , the participants were segregated into egoists and a group of collectivists .
`` proposal of the environment '' is the stochastically generated vector of algebraic increments of capitals .
the social dynamics was defined by the sequence of proposals accepted by threshold - majority voting .
analytical expressions of the expected values of the capitals of participants , collectivists and egoists were obtained .
distinctions of some principles of group voting were discussed . .
And you have already written the first three sentences of the full article: a model where the participants vote for the projects of redistribution of their own property was analyzed by a.v .
malishevskii in the late 1960 s [ 1 , pp .
9395 ] . in this model.
Please generate the next two sentences of the article | , voting is greatly manipulatable by the organizers , as it is the case with the participants whose `` ideals '' are the points in the multidimensional space of programs [ 2 ] ( see also [ 3 ] ) .
the monograph [ 4 ] is devoted to the spatial voting models . |
4,278 | Suppose that you have an abstract for a scientific paper: it is shown that the instanton - induced interaction in qq pairs , iterated in t - channel , leads to a meson - exchange interactions between quarks . in this way
one can achieve a simultaneous understanding of low - lying mesons , baryons and the nuclear force .
the discussion is general and does not necessarily rely on the instanton - induced interaction .
any nonperturbative gluonic interaction between quarks , which is a source of the dynamical chiral symmetry breaking and explains the @xmath0 - @xmath1 mass splitting , will imply an effective meson exchange picture in baryons . due to
the ( anti)screening there is a big difference between the initial t hooft interaction and the effective meson - exchange interaction .
it is demonstrated that the effective meson - exchange interaction , adjusted to the baryon spectrum , does not bind the scalar diquark and does not induce any significant quark - diquark clustering in the nucleon because of the nontrivial role played by the pauli principle .
pacs number(s ) : 12.38.lg , 12.39.-x , 14.20.dh .
And you have already written the first three sentences of the full article: speculations that instantons could induce diquark condensation in low temperature but high density quark matter @xcite have revived the interest in the diquark clustering in the nucleon .
it is sometimes also argued that diquark condensation may occur even at moderate densities , for example in heavy nuclei .
this problem is strongly related to the question of instanton induced diquark clustering in the nucleon ..
Please generate the next two sentences of the article | indeed , the instanton - induced t hooft interaction is strongly attractive for a quark - quark pair with quantum numbers @xmath2 ( scalar diquark ) .
this raises expectations that it binds a scalar diquark and is responsible for the scalar diquark - quark structure of the nucleon @xcite . |
4,279 | Suppose that you have an abstract for a scientific paper: we consider first order gravity in four dimensions . in particular , we consider formulations where the fundamental variables are a tetrad @xmath0 and a so(3,1 ) connection @xmath1 .
we study the most general action principle compatible with diffeomorphism invariance .
this implies , in particular , considering besides the standard einstein - hilbert - palatini term , other terms that either do not change the equations of motion , or are topological in nature .
having a well defined action principle also implies adding additional boundary terms , whose detailed form may depend on the particular boundary conditions at hand .
we consider spacetimes that include a boundary at infinity , satisfying asymptotically flat boundary conditions and/or an internal boundary satisfying isolated horizons boundary conditions . for our analysis
we employ the covariant hamiltonian formalism where the phase space @xmath2 is given by solutions to the equation of motion . for each of the possible terms contributing to the action we study the well posedness of the action , its finiteness , the contribution to the symplectic structure , and the hamiltonian and noether charges .
we show that for the chosen boundary conditions , standard boundary terms warrant a well posed theory .
furthermore , we show that the boundary and topological terms do not contribute to the symplectic structure , nor the hamiltonian conserved charges .
the noether conserved charges , on the other hand , do depend on such additional terms .
the aim of the paper is to present a comprehensive and self - contained treatment of the subject , so the style is somewhat pedagogical .
furthermore , we point out and clarify some issues that have not been clearly understood in the literature . .
And you have already written the first three sentences of the full article: one of the main lessons from the general theory of relativity is that one can formulate theories that , in their lagrangian description , are diffeomorphism invariant .
this means that one can perform generic diffeomorphism on the spacetime manifold and the theory remains invariant . in most instances diffeo invariance is achieved by formulating the theory as an action principle where the lagrangian density is defined without the use of background structures ; it is only the dynamical fields that appear in the action . in this manner one incorporates the ` stage ' , the gravitational field , as one of the dynamical fields that one can describe .
the fact that one can write a term that captures the dynamics of the gravitational field is interesting by itself ..
Please generate the next two sentences of the article | it is then worth exploring all the freedom available in the definition of an action principle for general relativity .
this is the main task that we shall undertake in this article . |
4,280 | Suppose that you have an abstract for a scientific paper: the diagonal in a product of projective spaces is cut out by the ideal of @xmath0-minors of a matrix of unknowns . the multigraded hilbert scheme which classifies its degenerations has a unique borel - fixed ideal .
this hilbert scheme is generally reducible , and its main component is a compactification of @xmath1 . for @xmath2
we recover the manifold of complete collineations . for projective lines
we obtain a novel space of trees that is irreducible but singular .
all ideals in our hilbert scheme are radical .
we also explore connections to affine buildings and deligne schemes . .
And you have already written the first three sentences of the full article: multigraded hilbert schemes parametrize families of ideals in a polynomial ring that share the same hilbert function with respect to some grading by an abelian group @xcite .
we are interested in the following particular case .
let @xmath3 be a @xmath4-matrix of unknowns ..
Please generate the next two sentences of the article | we fix the polynomial ring @xmath5 $ ] over a field @xmath6 with the @xmath7-grading by column degree , i.e. @xmath8 . in this grading ,
the hilbert function of the polynomial ring @xmath5 $ ] equals @xmath9 we study the multigraded hilbert scheme @xmath10 , which parametrizes @xmath7-homogeneous ideals @xmath11 in @xmath5 $ ] such that @xmath5/i$ ] has the hilbert function @xmath12 the key example is the ideal @xmath13 that is generated by the @xmath0-minors of @xmath14 , and whose quotient is indeed @xmath7-graded with hilbert function ( [ eqn : ourhf ] ) . |
4,281 | Suppose that you have an abstract for a scientific paper: as part of several h@xmath0i synthesis mapping studies of merging galaxies , we have mapped the tidal gas in the three disk - disk merger systems arp 157 ( ngc 520 ) , arp 220 , and arp 299 ( ngc 3690 ) .
these systems differ from the majority of the mergers mapped in h@xmath0i , in that their stellar and gaseous tidal features do not coincide .
in particular , they exhibit large stellar tidal features with little if any accompanying neutral gas and large gas - rich tidal features with little if any accompanying starlight
. on smaller scales , there are striking anti - correlations where the gaseous and stellar tidal features appear to cross .
we explore several possible causes for these differences , including dust obscuration , ram pressure stripping , and ionization effects .
no single explanation can account for all of the observed differences .
the fact that each of these systems shows evidence for a starburst driven superwind expanding in the direction of the most striking anti - correlations leads us to suggest that the superwind is primarily responsible for the observed differences , either by sweeping the features clear of gas via ram pressure , or by excavating a clear sightline towards the starburst and allowing uv photons to ionize regions of the tails . if this suggestion is correct , only systems hosting a galactic superwind and experiencing a high - inclination encounter geometry ( such that tidal gas is lifted high above the starburst regions ) should exhibit such extreme differences between their h@xmath0i and optical tidal morphologies .
= cmcsc10 at 12pt = cmcsc10 = cmr12 = cmr10 # 1@xmath1 # 1@xmath2 .
And you have already written the first three sentences of the full article: nearly 30 years ago , toomre & toomre ( 1972 ) elegantly demonstrated that the tails and bridges emanating from many peculiar galaxies may arise kinematically from dynamically cold disk material torn off of the outer regions of galaxies experiencing strong gravitational interactions .
early spectroscopic studies of gas within the tidal tails of merging galaxies provided observational support for this hypothesis by showing the tails to have the kinematics expected for a gravitational origin ( e.g. stockton 1974a , b ) .
h@xmath0i mapping studies are particularly well suited to such studies , as the tidally ejected disk material is usually rich in neutral hydrogen and can be traced to very large distances from the merging systems ( e.g. van der hulst 1979 ; simkin _ et al . _ 1986.
Please generate the next two sentences of the article | ; appleton _ et al . _
1981 , 1987 ; yun _ et al . _ 1994 ) . |
4,282 | Suppose that you have an abstract for a scientific paper: we establish a connection between measurement - based quantum computation and the field of mathematical logic .
we show that the computational power of an important class of quantum states called _ graph states _ , representing resources for measurement - based quantum computation , is reflected in the expressive power of ( classical ) formal logic languages defined on the underlying mathematical graphs .
in particular , we show that for all graph state resources which can yield a computational speed - up with respect to classical computation , the underlying graphs describing the quantum correlations of the states are associated with _
undecidable _ logic theories . here
undecidability is to be interpreted in a sense similar to gdel s incompleteness results , meaning that there exist propositions , expressible in the above classical formal logic , which can not be proven or disproven . .
And you have already written the first three sentences of the full article: quantum computers are devices that use quantum mechanics for enhanced ways of information processing @xcite .
indeed , it is known that problems such as integer factoring can be performed significantly faster on a quantum computer than on any known classical device @xcite . despite these exciting perspectives , the questions : _ `` what are the essential resources that give quantum computers their computational power '' _ , and _ `` are quantum computers fundamentally more powerful than classical devices ? '' _ remain to date largely unanswered .
the existence of several models for quantum computation , each based on different concepts , indicates that there may not be a straightforward answer to these difficult questions . the new paradigm of _ measurement - based _ , or _.
Please generate the next two sentences of the article | one - way _ quantum computation @xcite , @xcite has lead to novel perspectives in these respects .
the introduction of this model established that certain many - qubit quantum states , such as the _ |
4,283 | Suppose that you have an abstract for a scientific paper: a facet of an hyperplane arrangement is called external if it belongs to exactly one bounded cell .
the set of all external facets forms the envelope of the arrangement .
the number of external facets of a simple arrangement defined by @xmath0 hyperplanes in dimension @xmath1 is hypothesized to be at least @xmath2 . in this note
we show that , for simple arrangements of @xmath3 lines or more , the minimum number of external facets is equal to @xmath4 , and for simple arrangements of @xmath5 planes or more , the minimum number of external facets is between @xmath6 and @xmath7 . .
And you have already written the first three sentences of the full article: let @xmath8 be a simple arrangement formed by @xmath0 hyperplanes in dimension @xmath1 .
we recall that an arrangement is called simple if @xmath9 and any @xmath1 hyperplanes intersect at a distinct point .
the closures of connected components of the complement of the hyperplanes forming @xmath10 are called the cells , or @xmath1-faces , of the arrangement . for @xmath11 ,.
Please generate the next two sentences of the article | the @xmath12-faces of @xmath10 are the @xmath12-faces of its cells .
a facet is a @xmath13-face of @xmath8 , and a facet belonging to exactly one bounded cell is called an external facet . |
4,284 | Suppose that you have an abstract for a scientific paper: new experimental data obtained mainly at the gsi / frs facility allow to modify the empirical parametrization of fragmentation cross sections , epax .
it will be shown that minor modifications of the parameters lead to a much better reproduction of measured cross sections .
the most significant changes refer to the description of fragmentation yields close to the projectile and of the memory effect of neutron - deficient projectiles . .
And you have already written the first three sentences of the full article: the pioneering experiments of projectile fragmentation at relativistic energies of @xmath0ar and @xmath1ca beams at the lbl bevalac @xcite have demonstrated the potential of this method for the production of exotic nuclei .
based on these ideas , the sis / frs facility @xcite at gsi has used also heavier projectiles like e.g. @xmath2ni , @xmath3kr , @xmath4xe , and @xmath5pb to produce and study exotic nuclei @xcite . for planning such experiments ,
when count - rate predictions are needed , analytical descriptions of fragmentation cross sections are useful ..
Please generate the next two sentences of the article | they are also useful in simulation programs for projectile - fragment separators ( like e.g. intensity @xcite or mocadi @xcite ) .
compared to physical models of high - energy fragmentation reactions , which in general involve time - consuming monte - carlo calculations , the virtue of an analytical formula lies in the short computing time and the possibility to calculate easily sub - microbarn cross sections that are beyond the reach of physical - model calculations . in 1990 , smmerer _ et al . _ |
4,285 | Suppose that you have an abstract for a scientific paper: we show that the increments of generalized wiener process , useful to describe non - gaussian white noise sources , have the properties of infinitely divisible random processes . using functional approach and the new correlation formula for non - gaussian white noise we derive directly from langevin equation , with such a random source , the kolmogorov s equation for markovian non - gaussian process . from this equation
we obtain the fokker - planck equation for nonlinear system driven by white gaussian noise , the kolmogorov - feller equation for discontinuous markovian processes , and the fractional fokker - planck equation for anomalous diffusion .
the stationary probability distributions for some simple cases of anomalous diffusion are derived . .
And you have already written the first three sentences of the full article: stochastic dynamics is useful to model many biological , chemical , economical and physical systems .
the random driving forces have very different origins , in most cases they are gaussian white or colored noise sources , but often these forces must be considered as non - gaussian ones , for example , in sensory and biological systems @xcite . moreover , in many physical and biological systems a deviation of real statistics of fluctuations from gaussian law , leading to anomalous diffusion , is observed @xcite . a suitable mathematical model to describe the anomalous diffusion is the fractional fokker - planck equation , which can be derived from different theoretical approaches @xcite . in this paper
we show that the increments of generalized wiener process , representing the integral of non - gaussian white noise , have the properties of infinitely divisible random processes ..
Please generate the next two sentences of the article | this enables us to obtain the characteristic functional of non - gaussian white noise .
then , by using functional approach to split the correlation between stochastic functionals , we derive the kolmogorov s equation directly from langevin equation with non - gaussian white noise source . from this general equation |
4,286 | Suppose that you have an abstract for a scientific paper: we explicitly calculate the lowest order systematic inhomogeneity - induced corrections to the cosmological constant that one would infer from an analysis of the luminosities and redshifts of type ia supernovae , assuming a homogeneous universe .
the calculation entails a post - newtonian expansion within the framework of second order perturbation theory , wherein we consider the effects of subhorizon density perturbations in a flat , dust dominated universe . within this formalism ,
we calculate luminosity distances and redshifts along the past light cone of an observer .
the luminosity distance - redshift relation is then averaged over viewing angles and ensemble averaged , assuming that density fluctuations at a given cosmic time are a homogeneous random process .
the resulting relation is fit to that of a homogeneous model containing dust and a cosmological constant , in order to deduce the best - fit cosmological constant density @xmath0 .
we find that the luminosity distance - redshift relation is indeed modified , even for large sample sizes , but only by a very small fraction , of order @xmath1 for @xmath2 .
this lowest order deviation depends on the peculiar velocities of the source and the observer . however , when fitting this perturbed relation to that of a homogeneous universe , via maximizing a likelihood function , we find that the inferred cosmological constant can be surprisingly large , depending on the range of redshifts sampled . for a sample of supernovae extending from @xmath3 out to a limiting redshift @xmath4 , we find that @xmath5 .
the value of @xmath0 has a large variance , and its magnitude tends to get progressively larger as the limiting redshift @xmath6 gets smaller , implying that precision measurements of @xmath0 from nearby supernova data will require taking this effect into account .
this effect has been referred to in the past as the fitting problem " , and more recently as subhorizon backreaction " .
we find that it is likely too small to explain the....
And you have already written the first three sentences of the full article: it appears as though the universe is expanding at an accelerating rate , as has been deduced from luminosity distance measurements of type ia supernovae , which appear dimmer than one would expect based on general relativity without a cosmological constant @xcite .
this acceleration has also been deduced from measurements of the current matter density @xmath8 , which is too small to close the universe as required by cosmic microwave background radiation ( cmb ) observations with @xmath9 priors from hst @xcite .
explanations for this discrepancy have been put forward , but most employ a modification of general relativity on cosmological scales or the addition of an exotic dark energy " field . there have also been attempts to explain this seemingly anomalous cosmic acceleration as a consequence of subhorizon inhomogeneity , rather than modified gravity or dark energy ..
Please generate the next two sentences of the article | a perturbation is referred to as subhorizon " if its wavelength is small compared to the hubble length : @xmath10 .
it has been suggested that small - scale density perturbations could cause the appearance of accelerated expansion without the need to introduce any form of dark energy , which is an appealing prospect @xcite . |
4,287 | Suppose that you have an abstract for a scientific paper: we investigate the internal consistency of the halo dark matter model which has been proposed by de boer et al .
to explain the excess of diffuse galactic gamma rays observed by the egret experiment .
any model based on dark matter annihilation into quark jets , such as the supersymmetric model proposed by de boer et al .
, inevitably also predicts a primary flux of antiprotons from the same jets . since propagation of the antiprotons in the unconventional , disk - dominated type of halo model used by de boer et al .
is strongly constrained by the measured ratio of boron to carbon nuclei in cosmic rays , we investigate the viability of the model using the darksusy package to compute the gamma - ray and antiproton fluxes .
we are able to show that their model is excluded by a wide margin from the measured flux of antiprotons .
we therefore find that a model of the type suggested by moskalenko et al . , where the intensities of protons and electrons in the cosmic rays vary with galactic position , is far more plausible to explain the gamma excess .
lapth1141/06 0.2 cm * is the dark matter interpretation of the egret gamma excess * * compatible with antiproton measurements ? *
lars bergstrm , joakim edsj , michael gustafsson _ department of physics , stockholm university , albanova university center , _ _ se-106 91 stockholm , sweden _ pierre salati _ laboratoire dannecy - le - vieux de physique thorique lapth , cnrs and universit de savoie , _
_ 9 , chemin de bellevue , b.p.110 74941 annecy - le - vieux , france _ .
And you have already written the first three sentences of the full article: in a series of papers , de boer et al . @xcite have put forward the idea that the well - known egret excess of diffuse galactic gamma rays @xcite could be well explained by dark matter annihilations .
the idea that excess from the region near the galactic center may be due to dark matter annihilations has a long history ( at least @xcite ) but de boer et al .
have extended this idea to claim that all the diffuse galactic gamma rays detected above 1 gev by the egret satellite , irrespective of the direction , has a sizeable dark matter contribution ( for a similar , but less explicit , proposal , see @xcite ) ..
Please generate the next two sentences of the article | de boer et al .
propose specific supersymmetric models as examples of viable models with correct relic density , and the gamma - ray fluxes are made to fit the observations . |
4,288 | Suppose that you have an abstract for a scientific paper: this paper considers a @xmath0-user single - input - single - output interference channel with inter - symbol interference ( isi ) , in which the channel coefficients are assumed to be linear time - invariant with finite - length impulse response .
the primary finding of this paper is that , with no channel state information at a transmitter ( csit ) , the sum - spectral efficiency can be made to scale linearly with @xmath0 , provided that the desired links have longer impulse response than do the interfering links .
this linear gain is achieved by a novel multi - carrier communication scheme which we call _ interference - free orthogonal frequency division multiplexing ( if - ofdm)_. furthermore , when a transmitter is able to learn csit from its paired receiver only , a higher sum - spectral efficiency can be achieved by a two - stage transmission method that concatenates if - ofdm and vector coding based on singular value decomposition with water - filling power allocation .
a major implication of the derived results is that separate encoding across subcarriers per link is sufficient to linearly increase the sum - spectral efficiency with @xmath0 in the interference channel with isi .
simulation results support this claim . .
And you have already written the first three sentences of the full article: in multi - user wideband wireless systems , two fundamental obstacles limit the gains in spectral efficiency : * inter - symbol interference ( isi ) : in a wideband communication system that uses a band - limited signal , isi is fundamentally unavoidable when the transmission bandwidth @xmath1 exceeds the coherence bandwidth @xmath2 of the channel .
isi distorts the signal between subsequent transmitted symbols ; this effect limits the spectral efficiency of a wideband communication system . * inter - user interference ( iui ) : in a multi - cell communication system that uses universal frequency reuse per cell , iui ( or inter - cell interference ) is also inevitable .
iui limits the spectral efficiency of the multi - cell system , because it reduces signal - to - interference plus noise ratio ( sinr ) of the users ..
Please generate the next two sentences of the article | the problem of mitigating both isi and iui simultaneously is challenging in general .
the common approach has been to deal with the problem of mitigating them separately . |
4,289 | Suppose that you have an abstract for a scientific paper: mark correlations provide a systematic approach to look at objects both distributed in space and bearing intrinsic information , for instance on physical properties .
the interplay of the objects properties ( marks ) with the spatial clustering is of vivid interest for many applications ; are , e.g. , galaxies with high luminosities more strongly clustered than dim ones ?
do neighbored pores in a sandstone have similar sizes ?
how does the shape of impact craters on a planet depend on the geological surface properties ? in this article
, we give an introduction into the appropriate mathematical framework to deal with such questions , i.e. the theory of marked point processes . after having clarified the notion of segregation effects
, we define universal test quantities applicable to realizations of a marked point processes .
we show their power using concrete data sets in analyzing the luminosity - dependence of the galaxy clustering , the alignment of dark matter halos in gravitational @xmath0-body simulations , the morphology- and diameter - dependence of the martian crater distribution and the size correlations of pores in sandstone . in order to understand our data in more detail
, we discuss the boolean depletion model , the random field model and the cox random field model .
the first model describes depletion effects in the distribution of martian craters and pores in sandstone , whereas the last one accounts at least qualitatively for the observed luminosity - dependence of the galaxy clustering . draft .
And you have already written the first three sentences of the full article: observations of spatial patterns at various length scales frequently are the only point where the physical world meets theoretical models . in many cases
these patterns consist of a number of comparable objects distributed in space such as pores in a sandstone , or craters on the surface of a planet .
another example is given in figure [ fig : kerscher_galaxies - circles ] , where we display the galaxy distribution as traced by a recent galaxy catalogue ..
Please generate the next two sentences of the article | the galaxies are represented as circles centered at their positions , whereas the size of the circles mirrors the luminosity of a galaxy . in order to test to which extent theoretical predictions fit the empirically found structures of that type
, one has to rely on quantitative measures describing the physical information . |
4,290 | Suppose that you have an abstract for a scientific paper: motivated by phenomenological models of hidden local symmetries and the ideas of dimensional deconstruction and gauge / gravity duality , we consider the model of an `` open moose . ''
such a model has a large number @xmath0 of hidden gauge groups as well as a global chiral symmetry . in the continuum limit
@xmath1 the model becomes a 4 + 1 dimensional theory of a gauge field propagating in a dilaton background and an external space - time metric with two boundaries .
we show that the model reproduces several well known phenomenological and theoretical aspects of low - energy hadron dynamics , such as vector meson dominance .
we derive the general formulas for the mass spectrum , the decay constants of the pion and vector mesons , and the couplings between mesons .
we then consider two simple realizations , one with a flat metric and another with a `` cosh '' metric interpolating between two ads boundaries .
for the pion form factor , the single pole @xmath2-meson dominance is exact in the latter case and approximate in the former case .
we discover that an ads / cft - like prescription emerges in the computation of current - current correlators .
we speculate on the role of the model in the theory dual to qcd . .
And you have already written the first three sentences of the full article: vector mesons ( @xmath3 , @xmath4 , etc . ) play a significant role in hadronic physics .
their interactions , though not constrained by low - energy theorems , apparently follow the broad pattern of vector meson dominance ( vmd ) @xcite .
there have been numerous efforts to incorporate vector mesons into field - theoretical frameworks ..
Please generate the next two sentences of the article | historically , the yang - mills theory was discovered in an early attempt to treat the @xmath2 meson @xcite .
more recently , interesting schemes based on `` hidden local symmetries '' ( hls ) were developed by bando _ |
4,291 | Suppose that you have an abstract for a scientific paper: a system of coupled chaotic bistable maps on a lattice with randomly distributed impurities is investigated as a model for studying the phenomenon of phase growth in nonuniform media .
the statistical properties of the system are characterized by means of the average size of spatial domains of equivalent spin variables that define the phases .
it is found that the rate at which phase domains grow becomes smaller when impurities are present and that the average size of the resulting domains in the inhomogeneous state of the system decreases when the density of impurities is increased .
the phase diagram showing regions where homogeneous , heterogeneous , and chessboard patterns occur on the space of parameters of the system is obtained . a critical boundary that separates the regime of slow growth of domains from the regime of fast growth in the heterogeneous region of the phase diagram is calculated .
the transition between these two growth regimes is explained in terms of the stability properties of the local phase configurations .
our results show that the inclusion of spatial inhomogeneities can be used as a control mechanism for the size and growth velocity of phase domains forming in spatiotemporal systems . .
And you have already written the first three sentences of the full article: there has been much recent interest in the study of spatiotemporal dynamical processes on nonuniform or complex networks . in this context ,
coupled map lattices @xcite have provided fruitful and computationally efficient models for the investigation of a variety of dynamical processes in spatially distributed systems . in particular , the discrete - space character of coupled map systems makes them specially appropriate for the investigation of spatiotemporal dynamics on nonuniform networks that can represent models of heterogeneous media .
the nonuniformity may be due to the intrinsic heterogeneous nature of the substratum , typical of pattern formation in biological contexts , or it may arise from random imperfections or fluctuations in the medium at some length scales ..
Please generate the next two sentences of the article | such heterogeneities can have significant effects on the formation of spatial patterns , for example , they can induce reberverators in excitable media and defects can serve as nucleation sites for domain growth processes .
recently , the study of the phase - ordering properties of systems of coupled chaotic maps and their relationship with ising models in statistical physics has been a focus of attention @xcite . |
4,292 | Suppose that you have an abstract for a scientific paper: recently taylor and socolar introduced an aperiodic mono - tile .
the associated tiling can be viewed as a substitution tiling .
we use the substitution rule for this tiling and apply the algorithm of @xcite to check overlap coincidence .
it turns out that the tiling has overlap coincidence .
so the tiling dynamics has pure point spectrum and we can conclude that this tiling has a quasicrystalline structure .
* keywords * : mono - tile tiling , quasicrystals , pure point diffraction / dynamical spectrum , self - affine tilings , overlap coincidence .
shigeki akiyama @xmath0 and jeong - yup lee @xmath1 .
And you have already written the first three sentences of the full article: _ aperiodic tiles _ are the set of prototiles which tile the space with their isomorphic images by euclidean motions ( composition of translations , rotations and reflections ) but only in non - periodic way .
there have been many examples of aperiodic tiles and study on them @xcite .
two of well - known examples of aperiodic tiles with simple prototiles up to euclidean motions are penrose tiles and ammann tiles which are uncovered in the mid 70 s ..
Please generate the next two sentences of the article | these sets consist of two prototiles and it has been the smallest number of prototiles which form aperiodic tiles until recently . since then , people have been interested in finding a single prototile for an aperiodic tile .
this problem is coined as ` mono - tile ' problem or ` einstein ' problem ( one stone in german ) . |
4,293 | Suppose that you have an abstract for a scientific paper: hawkins ( 2004 ) reported on a class of naked " agn characterized by strong amplitude optical brightness variability and the complete absence of broad emission lines in the optical spectrum .
the variability suggests that the nucleus is seen directly , however the absence of broad lines contradicts the simple formulation of unified models for agn .
we present the results of quasi - simultaneous spectroscopic observations with xmm-_newton _ and ntt ( _ la silla _ ) of two naked " agn .
we confirm the naked " nature of q2131 - 427 for which no broad emission line components have been detected in the optical spectrum and its x - ray spectrum shows no signs of intrinsic absorption .
the optical and x - ray mismatch in this source can not be ascribed to a high nuclear dust - to - gas ratio and a compton thick nature is ruled out on the basis of the high f@xmath0/f@xmath1}$ ] ratio .
the broad line region ( blr ) may be completely absent in this source , possibly as a consequence of its low eddington ratio . on the other hand ,
the optical spectrum of q2130 - 431 shows h@xmath2 and h@xmath3 broad emission line components , revealing the presence of a blr .
a mild x - ray absorption is expected in intermediate type 1.8 seyfert galaxies like q2130 - 431 , however we put a very low upper limit on the column density ( @xmath4 2 @xmath5 @xmath6 @xmath7 ) , also the low balmer decrement suggests that the blr itself does not suffer from reddening .
we propose that in this object the blr is intrinsically weak , making a case of true " intermediate seyfert galaxy .
we also report on the x - ray detection of the abell 3783 galaxy cluster in the xmm-_newton _ field - of - view of the q2131 - 427 observation .
[ firstpage ] galaxies : active - galaxies : seyfert - x - rays : galaxies - galaxies : clusters : general .
And you have already written the first three sentences of the full article: the unified model for seyfert galaxies predicts that the differences observed between type 1 and type 2 seyfert galaxies are primarily due to orientation effects ( antonucci 1993 ) .
optical narrow emission lines present in both type 1 and type 2 seyfert s spectra are produced in the narrow line region ( nlr ) at @xmath8 pc scale from the nucleus .
optical broad emission lines originate in the broad line region ( blr ) at sub - pc scale ..
Please generate the next two sentences of the article | the latter are observed only in type 1 seyfert s spectra since , in type 2 seyferts , they are obscured by a molecular torus .
much evidence has been found in favor of this picture , such as the larger amount of absorbing material measured from x - ray observations in seyfert 2s with respect to seyfert 1s ( risaliti et al . |
4,294 | Suppose that you have an abstract for a scientific paper: observations of topological defects associated with stone - wales type transformations ( _ i.e. _ , bond rotations ) in high resolution transmission electron microscopy ( hrtem ) images of carbon nanostructures are at odds with the equilibrium thermodynamics of these systems . here , by combining aberration - corrected hrtem experiments and atomistic simulations , we show that such defects can be formed by single electron impacts , and remarkably , at electron energies below the threshold for atomic displacements .
we further study the mechanisms of irradiation - driven bond rotations , and explain why electron irradiation at moderate electron energies ( @xmath0100 kev ) tends to amorphize rather than perforate graphene .
we also show via simulations that stone - wales defects can appear in curved graphitic structures due to incomplete recombination of irradiation - induced frenkel defects , similar to formation of wigner - type defects in silicon . .
And you have already written the first three sentences of the full article: stone - wales defect @xcite @xmath1(55 - 77 ) is the simplest example of topological disorder in graphene and other @xmath2-hybridized carbon systems .
it can be formed by rotating a c - c bond by @xmath3 with regard to the midpoint of the bond referred to as the sw transformation so that four hexagons are turned into two pentagons and two heptagons .
this defect has received considerable amount of attention @xcite , because it has the lowest formation energy among all intrinsic defects in graphenic systems , and because it presumably plays an important role in plastic deformation of carbon nanotubes ( cnt ) under tension @xcite by relieving strain @xcite ..
Please generate the next two sentences of the article | it can also act as a source for dislocation dipoles @xcite . regardless of being the lowest energy defect in graphene @xcite and other @xmath2-hybridized carbon nanostructures ,
the @xmath1(55 - 77 ) needs about 5 ev to appear in graphene @xcite , and 35 ev in cnts with a diameter above 1 nm @xcite , which should lead to a negligible equilibrium concentration of such defects at room temperature . |
4,295 | Suppose that you have an abstract for a scientific paper: a powerful mathematical method for front instability analysis that was recently developed in the field of nonlinear dynamics is applied to the 1 + 1 ( spatial and time ) dimensional landau - lifshitz - gilbert ( llg ) equation . from the essential spectrum of the llg equation
, it is shown that the famous walker rigid body propagating domain wall ( dw ) is not stable against the spin wave emission . in the low field region
only stern spin waves are emitted while both stern and bow waves are generated under high fields . by using the properties of the absolute spectrum of the llg equation
, it is concluded that in a high enough field , but below the walker breakdown field , the walker solution could be convective / absolute unstable if the transverse magnetic anisotropy is larger than a critical value , corresponding to a significant modification of the dw profile and dw propagating speed . since the walker solution of 1 + 1 dimensional llg equation can be realized in experiments , our results could be also used to test the mathematical method in a controlled manner . .
And you have already written the first three sentences of the full article: the past century witnessed the quantum leap of the semiconductor industries which gave birth to the computer science and information technology .
we are now in an era in which information keeps being generated at a skyrocketing pace such that the net volume of information produced per day might be comparable to that accumulated after years one century ago . as an important participant ,
magnetic data recording now has assumed the major task of information documentation , through video tapes , hard disks , etc . in order to cope with the exponentially growing information volume ,.
Please generate the next two sentences of the article | the need to develop data storage devices with higher capacity and faster read / write operation speed is demanded .
this intrigue the development of spintronics - the pursuit to employ , in addition to the charge of electrons , their spin properties into applications . |
4,296 | Suppose that you have an abstract for a scientific paper: a simple , efficient , and accurate method is proposed to map multi - dimensional free energy landscapes .
the method combines the temperature - accelerated molecular dynamics ( tamd ) proposed in [ maragliano & vanden - eijnden , chem .
. lett . * 426 * , 168 ( 2006 ) ] with a variational reconstruction method using radial - basis functions for the representation of the free energy .
tamd is used to rapidly sweep through the important regions of the free energy landscape and compute the gradient of the free energy locally at points in these regions .
the variational method is then used to reconstruct the free energy globally from the mean force at these points .
the algorithmic aspects of the single - sweep method are explained in detail , and the method is tested on simple examples , compared to metadynamics , and finally used to compute the free energy of the solvated alanine dipeptide in two and four dihedral angles . .
And you have already written the first three sentences of the full article: the free energy ( or potential of mean force ) is the thermodynamic force driving structural processes such as conformational changes of macromolecules in aqueous solution , ligand binding at the active site of an enzyme , protein - protein association , etc .
the free energy gives information about both the rate at which these processes occur and the mechanism by which they occur .
this makes free energy calculations a central issue in biophysics ..
Please generate the next two sentences of the article | molecular dynamics ( md ) simulations provide a tool for performing such calculations on a computer in a way which is potentially both precise and inexpensive ( e.g. @xcite ) .
since a free energy is in essence the logarithm of a probability density function ( see ( [ eq : free ] ) below for a precise definition ) it can in principle be calculated by histogram methods based on the binning of an md trajectory . |
4,297 | Suppose that you have an abstract for a scientific paper: our chances to halt epidemic outbreaks rely on how accurately we represent the population structure underlying the disease spread .
when analyzing global epidemics this force us to consider metapopulation models taking into account intra- and inter - community interactions .
recently watts _
et al _ introduced a metapopulation model which accounts for several features observed in real outbreaks [ watts _ et al _ , pnas 102 , 11157 ( 2005 ) ] . in this work
i provide an analytical solution to this model , enhancing our understanding of the model and the epidemic outbreaks it represents .
first , i demonstrate that depending on the intra - community expected outbreak size and the fraction of social bridges the epidemic outbreaks die out or there is a finite probability to observe a global epidemics .
second , i show that the global scenario is characterized by resurgent epidemics , their number increasing with increasing the intra - community average distance between individuals .
finally , i present empirical data for the aids epidemics supporting the model predictions .
human populations are structured in communities representing geographical locations and other factors leading to partial segregation .
this population structure has a strong impact on the spreading patterns of infectious diseases among humans , forcing us to consider metapopulation models making an explicit distinction between the intra- inter - community interactions @xcite .
the increase in model realism is paid , however , by an increase in model complexity .
detailed metapopulation models are difficult to build and as a consequence they are available for a few locations in the world @xcite or they cover a single route of global transmission @xcite .
recently watts _
et al _
@xcite introduced a simple metapopulation model making an explicit distinction between the intra- and inter - community interactions . in spite of the model simplicity it accounts for several features observed in real epidemic....
And you have already written the first three sentences of the full article: figure [ fig1 ] illustrates the general features of an epidemic outbreak on a population structured in different communities . starting from an index case a disease spreads widely inside a community thanks to the frequent intra - community interactions .
in addition the disease is transmitted to other communities via individuals belonging to different communities .
while the inter - community interactions may be rare they are determinant to understand the overall outbreak progression . based on this picture.
Please generate the next two sentences of the article | i divide the population in two types or classes .
the _ locals _ belonging to a single community and the social _ bridges _ belonging to different communities . in a first approximation |
4,298 | Suppose that you have an abstract for a scientific paper: fast radio bursts ( frbs ) are millisecond - duration radio signals occurring at cosmological distances . however the physical model of frbs is mystery , many models have been proposed . here
we study the frequency distributions of peak flux , fluence , duration and waiting time for the repeating frb 121102 .
the cumulative distributions of peak flux , fluence and duration show power - law forms .
the waiting time distribution also shows power - law distribution , and is consistent with a non - stationary poisson process .
these distributions are similar as those of soft gamma repeaters ( sgrs ) .
we also use the statistical results to test the proposed models for frbs .
these distributions are consistent with the predictions from avalanche models of slowly driven nonlinear dissipative systems . .
And you have already written the first three sentences of the full article: fast radio bursts ( frbs ) are intense radio flashes occurring at high galactic latitudes with anomalously high dispersion measure ( dm ) @xcite .
duo to the lack of distance information , their physical origin is unknown .
some people suggested that the high dm is dominated by the ionized intergalactic medium , which implies that frbs may occur at cosmological distances ..
Please generate the next two sentences of the article | recently , keane et al .
( 2016 ) claimed to discover the first frb host galaxy , which is an elliptical galaxy at @xmath0 @xcite . |
4,299 | Suppose that you have an abstract for a scientific paper: the notions of entanglement witnesses , separable and entangled states for two qubits system can be visualized in three dimensions using the slocc equivalence classes .
this visualization preserves the duality relations between the various sets and allows us to give `` proof by inspection '' of a non - elementary result of the horodeckies that for two qubits , peres separability test is iff .
we then show that the chsh bell inequalities can be visualized as circles and cylinders in the same diagram .
this allows us to give a geometric proof of yet another result of the horodeckies , which optimizes the violation of the chsh bell inequality .
finally , we give numerical evidence that , remarkably , allowing alice and bob to use three rather than two measurements each , does not help them to distinguish any new entangled slocc equivalence class beyond the chsh class . .
And you have already written the first three sentences of the full article: the world of 2 qubits is the simplest setting where the notions of entanglement @xcite , bell inequalities @xcite and their witnesses @xcite , first appear
. it would be nice if , like the bloch sphere for one qubit @xcite , they could also be visualized geometrically .
however , the world of two qubits is represented by @xmath0 hermitian matrices and being 16 dimensional it is not readily visualized ..
Please generate the next two sentences of the article | it can , however , be visualized by introducing an appropriate equivalence relation .
this idea has been used in @xcite to describe the separable and entangled states . here |
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