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6,100 | Suppose that you have an abstract for a scientific paper: we study ground states and elementary excitations of a system of bosonic atoms and diatomic feshbach molecules trapped in a one - dimensional optical lattice using exact diagonalization and variational monte carlo methods .
we primarily study the case of an average filling of one boson per site . in agreement with bosonization theory ,
we show that the ground state of the system in the thermodynamic limit corresponds to the pfaffian - like state when the system is tuned towards the superfluid - to - mott insulator quantum phase transition .
our study clarifies the possibility of the creation of exotic pfaffian - like states in realistic one - dimensional systems .
we also present preliminary evidence that such states support non - abelian anyonic excitations that have potential application for fault - tolerant topological quantum computation . .
And you have already written the first three sentences of the full article: the possibility of a fault - tolerant topological quantum computation @xcite based upon topological quasiparticles that obey non - abelian statistics ( non - abelian anyons ) @xcite motivated much recent interest in the new systems that support such quasiparticles .
the idea behind the topological quantum computation is that non - abelian anyons could be used to encode and manipulate information in a way that is resistant to error .
namely , if a quantum system has topological degrees of freedom , like non - abelian anyons , then the information contained in those degrees of freedom will be protected against errors caused by local interactions with the environment ..
Please generate the next two sentences of the article | this provides the possibility of using such systems to perform fault - tolerant quantum computation without decoherence .
non - abelian states of matter also present the fundamental intellectual challenge of principle and of experimental realization @xcite . |
6,101 | Suppose that you have an abstract for a scientific paper: testing extra dimensions at low - energies may lead to interesting effects . in this work a test point charge is taken to move uniformly in the 3-dimensional subspace of a ( 3+@xmath0)-brane embedded in a ( 3+@xmath0 + 1)-space with @xmath0 compact and one warped infinite spatial extra dimensions .
we found that the electromagnetic potentials of the point charge match standard liennard - wiechert s at large distances but differ from them close to it .
these are finite at the position of the charge and produce finite self - energies .
we also studied a localized hydrogen atom and take the deviation from the standard coulomb potential as a perturbation .
this produces a lamb shift that is compared with known experimental data to set bounds for the parameter of the model .
this work provides details and extends results reported in a previous letter .
+ _ keywords : brane worlds , liennard - wiechert , hydrogen atom , point charges . _ .
And you have already written the first three sentences of the full article: spacetimes with more than three spatial dimensions have been attracting interest for long time .
first proposals go back to kaluza and klein @xcite , in their attempt to unify electromagnetism with einstein gravity by proposing a theory with a compact fifth dimension of a size of the order of the planck length . later on
the emphasis shifted to a .
Please generate the next two sentences of the article | brane world " picture @xcite with our world being confined to a subspace of higher - dimensional spacetime .
more recently it was put forward , inspired also in @xcite , that at energy scales of the standard model matter can not propagate into extra dimensions whilst gravity on the other hand can permeate all over . within brane worlds extra dimensions may be compact but large @xcite , or infinite and warped @xcite . |
6,102 | Suppose that you have an abstract for a scientific paper: we consider the motion of test particles in thick branes of ` randall - sundrum ii'-type .
it is known that gravity alone can not explain the confinement of test particles in this kind of brane . in this paper
we show that a stable confinement in a domain wall is possible by admitting a direct interaction between test particles and a scalar field .
this interaction is implemented by a modification of the lagrangian of the particle which is inspired by a yukawa - type interaction between fermions and scalar fields .
pacs : 04.20.jb , 11.10.kk .
And you have already written the first three sentences of the full article: in braneworld scenarios it is assumed that our observable spacetime corresponds to a submanifold of a higher - dimensional ambient space .
basically this picture comes from the idea that matter and non - gravitational fields might be confined to the ordinary four - dimensional spacetime ( the brane ) by some trapping mechanism which would keep extra dimensions hidden from direct observations at an energy level below tev scale @xcite . of course
, for the sake of consistency , the existence of extra dimensions could not be revealed by gravitational probe either at lower energy regime ..
Please generate the next two sentences of the article | usually this is conceptually achieved by admitting the compactification of extra dimensions .
but , unlike kaluza - klein models , extra dimensions could be much larger than planck length in braneworld scenarios@xcite . |
6,103 | Suppose that you have an abstract for a scientific paper: we consider several examples of probabilistic existence proofs using compressibility arguments , including some results that involve lovsz local lemma . .
And you have already written the first three sentences of the full article: there are many well known probabilistic proofs that objects with some properties exist . such a proof estimates the probability for a random object to violate the requirements and shows that it is small ( or at least strictly less than @xmath0 )
let us look at a toy example . consider a @xmath1 boolean matrix and its @xmath2 minor ( the intersection of @xmath3 rows and @xmath3 columns chosen arbitrarily ) .
we say that the minor is _ monochromatic _ if all its elements are equal ( either all zeros or all ones ) . for large enough @xmath4 and for @xmath5 , there exists a @xmath6-matrix that does not contain a monochromatic @xmath7-minor ..
Please generate the next two sentences of the article | we repeat the same simple proof three times , in three different languages .
( probabilistic language ) let us choose matrix elements using independent tosses of a fair coin . |
6,104 | Suppose that you have an abstract for a scientific paper: we discuss the evolution of purity in mixed quantum / classical approaches to electronic nonadiabatic dynamics in the context of the ehrenfest model . as it is impossible to exactly determine initial conditions for a realistic system
, we choose to work in the statistical ehrenfest formalism that we introduced in ref . .
from it , we develop a new framework to determine exactly the change in the purity of the quantum subsystem along the evolution of a statistical ehrenfest system . in a simple case ,
we verify how and to which extent ehrenfest statistical dynamics makes a system with more than one classical trajectory and an initial quantum pure state become a quantum mixed one .
we prove this numerically showing how the evolution of purity depends on time , on the dimension of the quantum state space @xmath0 , and on the number of classical trajectories @xmath1 of the initial distribution .
the results in this work open new perspectives for studying decoherence with ehrenfest dynamics . .
And you have already written the first three sentences of the full article: the schrdinger equation for a combined system of electrons and nuclei enables us to predict most of the chemistry and molecular physics that surrounds us , including biophysical processes of great complexity .
unfortunately , this task is not possible in general , and approximations need to be made ; one of the most important and successful being the classical approximation for a number of the particles .
mixed quantum - classical dynamical ( mqcd ) models are therefore necessary and widely used ..
Please generate the next two sentences of the article | we could say that , typically , the technique used to build mqcd models is a partial ` deconstruction ' of the quantum mechanics ( qm ) of the total system ( electrons and nuclei ) followed by a ` reconstruction ' that tries to recover the essential properties of the total schrdinger equation lost in the deconstruction process .
it is unrealistic to expect the reconstructed theory has the same predictive power as the schrdinger equation , so the reconstructed theory will apply with enough accuracy only to a subset of systems and questions ; a subset whose boundaries are difficult to predict a priori . in the literature , there are at least two common levels of deconstruction , one further away from the total schrdinger equation for electrons and nuclei , called born - oppenheimer molecular dynamics ( bomd ) , where electrons are assumed to remain in the ground state for all times , and another one closer to it , called ehrenfest dynamics ( ed ) , where nuclei are still classical ( as in bomd ) but the electrons are allowed to populate excited states ( some misleading notation used in the literature on ed is clarified in section 2 of ref . ) . in j. c. tully s surface hopping methods,@xcite for example , the deconstruction goes to bomd and the reconstruction proceeds by allowing the system to perform certain specially designed stochastic jumps between adiabatic states . in the decay of mixing formalism by d. g. truhlar and |
6,105 | Suppose that you have an abstract for a scientific paper: we discuss a model for treating chemical enrichment by type ii and type ia supernova ( snii and snia ) explosions in simulations of cosmological structure formation .
our model includes metal - dependent radiative cooling and star formation in dense collapsed gas clumps .
metals are returned into the diffuse interstellar medium by star particles using a local smoothed particle hydrodynamics ( sph ) smoothing kernel .
a variety of chemical abundance patterns in enriched gas arise in our treatment owing to the different yields and lifetimes of snii and snia progenitor stars .
in the case of snii chemical production , we adopt metal - dependent yields . because of the sensitive dependence of cooling rates on metallicity , enrichment of galactic haloes with metals can in principle significantly alter subsequent gas infall and the build up of the stellar components .
indeed , in simulations of isolated galaxies we find that a consistent treatment of metal - dependent cooling produces @xmath0 per cent more stars outside the central region than simulations with a primordial cooling function . in the highly - enriched central regions , the evolution of baryons is however not affected by metal cooling , because here the gas is always dense enough to cool .
a similar situation is found in cosmological simulations because we include no strong feedback processes which could spread metals over large distances and mix them into unenriched diffuse gas .
we demonstrate this explicitly with test simulations which adopt suprasolar cooling functions leading to large changes both in the stellar mass and in the metal distributions .
we also find that the impact of metallicity on the star formation histories of galaxies may depend on their particular evolutionary history .
our results hence emphasise the importance of feedback processes for interpreting the cosmic metal enrichment .
[ firstpage ] methods : numerical - galaxies : abundances - galaxies : formation - galaxies : evolution - cosmology : theory . .
And you have already written the first three sentences of the full article: over the last decades , our knowledge of the chemical properties of the universe and , in particular , of galaxies , has improved dramatically .
observations of the local universe ( e.g. garnett & shields 1987 ; skillman , kennicutt & hodge 1989 ; brodie & huchra 1991 ; zaritsky , kennicutt & huchra 1994 ; mushotzky et al . 1996 ; ettori et al . 2002 ; tremonti et al . 2004 ; lamareille et al .
2004 ) as well as at intermediate and high redshifts ( e.g. prochaska & wolfe 2002 ; adelberger et al . 2003 ; kobulnicky et al . 2003.
Please generate the next two sentences of the article | ; lilly , carollo & stockton 2003 ; shapley et al .
2004 ) have resulted in a quite detailed picture of the chemical history of the stellar populations and of the interstellar and intergalactic media . |
6,106 | Suppose that you have an abstract for a scientific paper: magnetic plasma instabilities appear to play an important role in the early stages of quark - gluon plasma equilibration in the high energy ( weak coupling ) limit .
numerical studies of the growth of such instabilities from small seed fluctuations have found initial exponential growth in their energy , followed by linear growth once the associated color magnetic fields become so large that their non - abelian interaction are non - perturbative . in this paper , we use simulations to determine the nature of this linear energy growth .
we find that the long - wavelength modes associated with the instability have ceased to grow , but that they cascade energy towards the ultraviolet in the form of plasmon excitations of ever increasing energy .
we find a quasi - steady - state power - law distribution @xmath0 for this cascade , with spectral index @xmath1 .
# 1eq .
( [ # 1 ] ) l v c .
And you have already written the first three sentences of the full article: one of the surprises which has emerged from the heavy ion experiments at rhic is that the medium or plasma which is produced in a heavy ion collision appears to display collective behavior analogous to a fluid with a very small viscosity ( the so - called `` quark - gluon liquid '' ) @xcite . in particular
, hydrodynamic treatments taking the medium to be an ideal fluid give the correct flow description @xcite . to clarify ,
we remind the reader that `` ideal fluid '' is the opposite of `` ideal gas '' ; it means that scatterings or interactions so efficiently maintain local equilibrium ( or at least isotropy ) , that the stress tensor remains everywhere isotropic when measured in the local rest frame ..
Please generate the next two sentences of the article | gases behave like ideal fluids on distance and time scales large compared to transport mean free paths and mean free times .
the most popular , and perhaps most likely , explanation for the small viscosity is that the quark - gluon plasma at the energy densities achieved at rhic is very far from weak coupling . |
6,107 | Suppose that you have an abstract for a scientific paper: we propose a notion of a super @xmath0-lie algebra and construct a super @xmath0-lie algebra with the help of a given binary super lie algebra which is equipped with an analog of a supertrace .
we apply this approach to the super lie algebra of a clifford algebra with even number of generators and making use of a matrix representation of this super lie algebra given by a supermodule of spinors we construct a series of super 3-lie algebras labeled by positive even integers . .
And you have already written the first three sentences of the full article: in search for new fundamental structures in theoretical physics and mechanics the physicists are increasingly turning their attention to algebraic structures which are based on ternary multiplication law ( more generally on @xmath0-ary multiplication law ) . in 1973
y. nambu proposed a generalization of hamiltonian mechanics where he replaced a canonically conjugate pair of variables by a triple of canonical variables and the usual poisson bracket by a ternary operation ( nambu bracket ) @xcite . a geometric formalism for this generalization of hamiltonian mechanics based on a notion of nambu bracket of order @xmath0 , the fundamental identity and a concept of nambu - poisson manifold was developed by l. takhtajan in @xcite .
an important part of this geometric formalism is a notion of an @xmath0-lie algebra which was also studied by v. t. filippov in @xcite ..
Please generate the next two sentences of the article | j. arnlind , a. makhlouf and s. silvestrov constructed an @xmath0-lie algebra by means of a binary lie algebra endowed with an analog of a trace @xcite and this @xmath0-lie algebra was called an @xmath0-lie algebra induced by lie algebra .
they also studied the cohomologies of @xmath0-lie algebra induced by a lie algebra and found the relation of these cohomologies to the cohomology of initial binary lie algebra . in this paper |
6,108 | Suppose that you have an abstract for a scientific paper: we optimize the first and second intrinsic hyperpolarizabilities for a 1d piecewise linear potential dressed with dirac delta functions for @xmath0 non - interacting electrons .
the optimized values fall rapidly for @xmath1 , but approach constant values of @xmath2 , @xmath3 and @xmath4 above @xmath5 .
these apparent bounds are achieved with only 2 parameters with more general potentials achieving no better value .
in contrast to previous studies , analysis of the hessian matrices of @xmath6 and @xmath7 taken with respect to these parameters shows that the eigenvectors are well aligned with the basis vectors of the parameter space , indicating that the parametrization was well - chosen .
the physical significance of the important parameters is also discussed . .
And you have already written the first three sentences of the full article: nonlinear optical materials are the active constituent for many applications such as light modulators , contrast agents for medical imaging and therapy , optical solitons , phase conjugation mirrors and optical self - modulation . in each of these ,
the performance of the system is improved by using a material with a stronger nonlinear response , quantified by various nonlinear susceptibilities defined by expanding the induced polarization @xmath8 in a power series in the applied electric field , @xmath9 here , @xmath10 is the linear susceptibility familiar from dielectric materials ; @xmath11 and @xmath12 are the nonlinear susceptibilities and are referred to as the first and second hyperpolarizability respectively .
these quantities are in general frequency - dependent tensors that depend on the electronic structure of the constituent molecules , their symmetry , ordering and the material in which they are embedded . in the present work we focus on the off - resonant molecular contribution ..
Please generate the next two sentences of the article | much effort has been expended over the years in synthesizing new molecules with higher @xmath11 or @xmath12 .
comparisons between materials must be made carefully however , because these quantities increase trivially with the size of the molecule . |
6,109 | Suppose that you have an abstract for a scientific paper: as a basis for epistemological study of `` time , '' we analyze three suspect phenomena introduced by modern physics : non - locality , asymmetric aging and advanced interaction .
it is shown that all three arise in connection with what has to be taken as arbitrary ideosyncrasies in formulation .
it is shown that minor changes result in internally consistent variations of both quantum mechanics and special relativity devoid of these phenomena .
the reinterpretation of some experiments though to confirm the existence of non - locality and asymmetric aging is briefly considered and a possible test is proposed .
key words : non - locality , asymmetric aging , advanced interaction , quantum mechanics , relativity _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ draft for : _ proceedings , the nature of time : geometry , physics & perception ; + may 21 - 24 , 2002 , tatranska lomnica , slovak republic _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .
And you have already written the first three sentences of the full article: modern physics , specifically , quantum mechanics ( qm ) and special relativity ( sr ) , have brought three notions into common currency , namely : `` non - locality , '' `` asymmetric aging '' and `` advanced interaction , '' that defy accommodation with classical physics , common sense and , we hold , basic logic . how this came about
historically is well documented in the literature and so will not be belabored here .
although asymmetric aging , a.k.a . the `` twin paradox , '' has been a foil for ` nondomesticated ' newcomers and numerous outsiders for 90 years , all of these notions nowadays enjoy solid ensconcement in the corpus of `` verified physics . ''.
Please generate the next two sentences of the article | one reason for this appears to be their appeal as harbingers from the preternatural ; or as a foot - in - the - door leading out from the stolid , unromantic material world to a great mystical beyond .
another reason is that too little effort has been devoted to seeking alternatives out of respect for the profound successes of both qm and sr . |
6,110 | Suppose that you have an abstract for a scientific paper: the conventional absence of field renormalization in the local potential approximation ( lpa ) implying a zero value of the critical exponent @xmath0 is shown to be incompatible with the logic of the derivative expansion of the exact renormalization group ( rg ) equation .
we present a lpa with @xmath1 that strictly does not make reference to any momentum dependence .
emphasis is made on the perfect breaking of the reparametrization invariance in that pure lpa ( absence of any vestige of invariance ) which is compatible with the observation of a progressive smooth restoration of that invariance on implementing the two first orders of the derivative expansion whereas the conventional requirement ( @xmath2 in the lpa ) precluded that observation .
local potential approximation , derivative expansion , exact renormalization group equation , reparametrization invariance , anomalous dimension 05.10.cc , 11.10.gh , 11.10.hi , 64.60.ae , 02.60.lj .
And you have already written the first three sentences of the full article: the exact renormalization group ( rg ) equation @xcite ( erge ) also called non - perturbative or functional rg equation can not be concretely used without recourse to approximation ( for modern reviews or introductory lectures see , e.g. , @xcite ) . the best known approximation framework for
the erge is the derivative expansion @xcite .
the leading order of that expansion , @xmath3-order , also named the local potential approximation ( lpa ) @xcite , completely discards any momentum dependence from the study . in principle.
Please generate the next two sentences of the article | the lpa amounts to projecting the rg flow of the complete action @xmath4 $ ] ( a functional of the field @xmath5 ) onto the space of simple functions @xmath6 of a uniform field @xmath7 by assuming that:@xmath8 = \omega _ { d}\,u\left ( \phi \right ) \label{1}\]]where @xmath9 is the volume of the @xmath10-dimensional space . due to its simplicity and
because it is thought that it qualitatively involves most of the properties of the complete erge in the large distance regime ( e.g. , stability properties and number of fixed points ) , the lpa is currently utilized in many studies . |
6,111 | Suppose that you have an abstract for a scientific paper: we investigate the dynamic formation of regular random graphs . in our model , we pick a pair of nodes at random and connect them with a link if both of their degrees are smaller than @xmath0 . starting with a set of isolated nodes ,
we repeat this linking step until a regular random graph , where all nodes have degree @xmath0 , forms .
we view this process as a multivariate aggregation process , and formally solve the evolution equations using the hamilton - jacobi formalism .
we calculate the nontrivial percolation thresholds for the emergence of the giant component when @xmath1 . also , we estimate the number of steps until the giant component spans the entire system and the total number of steps until the regular random graph forms .
these quantities are non self - averaging , namely , they fluctuate from realization to realization even in the thermodynamic limit . .
And you have already written the first three sentences of the full article: a random graph is a set of nodes that are connected by random links @xcite .
when the number of links exceeds a certain threshold , a giant component with a finite fraction of all nodes emerges @xcite .
therefore , random graphs are equivalent to a mean - field percolation process @xcite ..
Please generate the next two sentences of the article | random graphs underlie many natural phenomena from polymerization @xcite to the spread of infectious diseases @xcite , and they are also used to model social networks @xcite as well as complexity of algorithms @xcite .
the classical random graph has no restrictions on the degree of a node . in many situations , |
6,112 | Suppose that you have an abstract for a scientific paper: we investigate the motion of a colloidal particle driven out of equilibrium by an external torque .
we use molecular dynamics simulation as an alternative to the langevin dynamics .
we prepare a heat bath composed of thousands of particles interacting with each other through the lennard - jones potential and impose the langevin thermostat to maintain heat bath in equilibrium .
we consider a single colloidal particle to interact with the particles of the heat bath also by the lennard - jones potential , without applying any types of dissipative and fluctuating forces used in the langevin dynamics .
we set up simulation protocol fit for the overdamped limit as in real experiments by increasing the size and mass of the colloidal particle .
we study nonequilibrium fluctuations for work and heat produced incessantly in time and compare results with those obtained from the previous studies via the overdamped langevin dynamics .
we confirm the gallavotti - cohen symmetry and the fluctuation theorem for the work production . .
And you have already written the first three sentences of the full article: nonequilibrium thermal fluctuations for a small system in contact with heat bath in equilibrium become very large and exhibit interesting properties that are universal over different systems .
the underlying principle for the universal properties is the fluctuation theorem ( ft ) , which was first discovered for a deterministic system thermostatted so as to conserve kinetic energy @xcite .
the ft was later proven to hold for a wide class of stochastic systems @xcite ..
Please generate the next two sentences of the article | it deals with the thermal fluctuations of thermodynamic quantities produced persistently in time , such as work and heat in a nonequilibrium process . a typical form of the ft is given by @xmath0 , where @xmath1 is the rate of work production piled over a period @xmath2 in nonequilibrium dynamics driven by a nonconservative force acting on the system initially prepared in equilibrium with heat bath .
@xmath3 is the inverse temperature @xmath4 for the boltzmann constant @xmath5 and the temperature @xmath6 of the heat bath . |
6,113 | Suppose that you have an abstract for a scientific paper: direct detection experiments are poised to detect dark matter in the form of weakly interacting massive particles ( wimps ) .
the signals expected in these experiments depend on the ultra - local wimp density and velocity distribution .
firstly we review methods for modelling the dark matter distribution .
we then discuss observational determinations of the local dark matter density , circular speed and escape speed and the results of numerical simulations of milky way - like dark matter halos . in each case
we highlight the uncertainties and assumptions made .
we then overview the resulting uncertainties in the signals expected in direct detection experiments , specifically the energy , time and direction dependence of the event rate .
finally we conclude by discussing techniques for handling the astrophysical uncertainties when interpreting data from direct detection experiments . .
And you have already written the first three sentences of the full article: weakly interacting massive particles ( wimps ) are a promising dark matter candidate as they are generically produced in the early universe with roughly the right density . furthermore supersymmetry ( susy ) provides a well - motivated concrete wimp candidate in the form of the lightest neutralino ( for reviews see e.g. refs . ) .
wimps can be directly detected in the lab via their elastic scattering off target nuclei @xcite .
numerous direct detection experiments are underway and they are probing the regions of wimp mass - cross - section parameter space populated by susy models ( see e.g. ref . ) ..
Please generate the next two sentences of the article | the realisation that uncertainties in the velocity distribution , @xmath0 , will affect the direct detection signals dates back to some of the earliest direct detection papers written in the 1980s ( e.g. ref . ) .
we first discuss the standard halo model and other approaches to modelling the milky way halo ( sec . [ modelling ] ) . |
6,114 | Suppose that you have an abstract for a scientific paper: i review the present state of knowledge on lepton energy spectra in the inclusive semileptonic decay of beauty hadrons ( @xmath0 ) as a means to measure @xmath1 polarization effects on the @xmath2 peak .
charged - lepton as well as neutrino spectra are considered .
ps .
# 1#2#3phys . lett . * # 1 * ( 19#2 ) # 3 # 1#2#3z . phys . * # 1 * ( 19#2 ) # 3 # 1#2#3phys .
rev .
lett . *
# 1 * ( 19#2 ) # 3 # 1#2#3phys . rep . * # 1 * ( 19#2 ) # 3 # 1#2#3phys . rev .
* # 1 * ( 19#2 ) # 3 # 1#2#3nucl . phys . * # 1 * ( 19#2 ) # 3 # 1#2#3acta phys . pol .
* # 1 * ( 19#2 ) # 3 # 1#2#3acta phys . austr . * # 1 * ( 19#2 ) # 3 # 1#2#3j .
comp .
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# 1 * ( 19#2 ) # 3 # 1#2#3prog .
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# 1 * ( 19#2 ) # 3 # 1#2#3int .
j. mod .
phys . *
# 1 * ( 19#2 ) # 3 0.0 cm 0.0 cm 15.2 cm 21.5 cm 0.7 cm -1.0 cm 2.0 cm # 1@xmath3 * preprint n.1009 * dipartimento di fisica + march 17 , 1994 universit di roma `` la sapienza '' + i.n.f.n .
- sezione di roma + * lepton spectra and the b polarization + at lep * c barbara mele + + _ i.n.f.n .
, sezione di roma , italy and _ + _ dipartimento di fisica , universit `` la sapienza '' , _ + _ p.le aldo moro 2 , i-00185 rome , italy _ + .
And you have already written the first three sentences of the full article: heavy quark physics offers a unique opportunity to explore the flavour structure of the standard model .
the third family of quarks is the less known .
its up - type quark , the top , has not yet been observed , although we are getting more and more stringent limits on its mass from direct search and radiative correction analysis . on the other hand , the corresponding down - type quark , the @xmath1 ,.
Please generate the next two sentences of the article | is being studied with increasing accuracy . both growing statistics and the operation of dedicated vertex detector for @xmath1 tagging at high energy machines already allows a good determination of @xmath1 couplings .
present data clearly point to the @xmath1 as the @xmath41/2 component of a weak left - handed isodoublet @xcite . |
6,115 | Suppose that you have an abstract for a scientific paper: we present nanoscale explosives as a novel type of dark matter detector and study the ignition properties .
when a weakly interacting massive particle wimp from the galactic halo elastically scatters off of a nucleus in the detector , the small amount of energy deposited can trigger an explosion . for specificity , this paper focuses on a type of two - component explosive known as a nanothermite , consisting of a metal and an oxide in close proximity .
when the two components interact they undergo a rapid exothermic reaction an explosion . as a specific example , we consider metal nanoparticles of 5 nm radius embedded in an oxide . one cell contains more than a few million nanoparticles , and a large number of cells adds up to a total of 1 kg detector mass .
a wimp interacts with a metal nucleus of the nanoparticles , depositing enough energy to initiate a reaction at the interface between the two layers .
when one nanoparticle explodes it initiates a chain reaction throughout the cell .
a number of possible thermite materials are studied .
excellent background rejection can be achieved because of the nanoscale granularity of the detector : whereas a wimp will cause a single cell to explode , backgrounds will instead set off multiple cells .
if the detector operates at room temperature , we find that wimps with masses above 100 gev ( or for some materials above 1 tev ) could be detected ; they deposit enough energy ( @xmath010 kev ) to cause an explosion .
when operating cryogenically at liquid nitrogen or liquid helium temperatures , the nano explosive wimp detector can detect energy deposits as low as 0.5 kev , making the nano explosive detector more sensitive to very light @xmath110 gev wimps , better than other dark matter detectors . .
And you have already written the first three sentences of the full article: the majority of the mass in the universe is known to consist of dark matter ( dm ) of unknown composition .
identifying the nature of this dark matter is one of the outstanding problems in physics and astrophysics .
leading candidates for this dark matter are weakly interacting massive particles ( wimps ) , a generic class of particles that includes the lightest supersymmetric particle ..
Please generate the next two sentences of the article | these particles undergo weak interactions and their expected masses range from 1 gev to 10 tev .
many wimps , if present in thermal equilibrium in the early universe , annihilate with one another , leaving behind a relic density found to be roughly the correct value . furthermore , recent interest in low mass wimps lead us to mention asymmetric dark matter models , which naturally predict light wimps @xcite . |
6,116 | Suppose that you have an abstract for a scientific paper: high resolution h@xmath0 rotation curves are presented for five low surface brightness galaxies .
these h@xmath0 rotation curves have shapes different from those previously derived from observations , probably because of the higher spatial resolution of the h@xmath0 observations .
the h@xmath0 rotation curves rise more steeply in the inner parts than the rotation curves and reach a flat part beyond about two disk scale lengths .
with radii expressed in optical disk scale lengths , the rotation curves of the low surface brightness galaxies presented here and those of hsb galaxies have almost identical shapes .
mass modeling shows that the contribution of the stellar component to the rotation curves may be scaled to explain most of the inner parts of the rotation curves , albeit with high stellar mass - to - light ratios . on the other hand ,
well fitting mass models can also be obtained with lower contributions of the stellar disk .
these observations suggest that the luminous mass density and the total mass density are coupled in the inner parts of these galaxies . .
And you have already written the first three sentences of the full article: the rotation curves of high surface brightness ( hsb ) spiral galaxies rise fairly steeply to reach an extended , approximately flat part , well within the optical disk ( bosma 1978 , 1981a , b ; rubin , ford , & thonnard 1978 , 1980 ) . the discovery that the rotation curves of these galaxies are more or less flat out to one or two holmberg radii has been one of the key pieces of evidence for the existence of dark matter outside the optical disk ( see also van albada et al . 1985 ) . within the optical disk ,
the observed rotation curves can in most cases be explained by the stellar components alone ( kalnajs 1983 ; kent 1986 ) .
the rotation curves of so - called low surface brightness ( lsb ) galaxies have been studied only recently ( de blok , mcgaugh , & van der hulst 1996 , hereafter bmh ; see also pickering et al ..
Please generate the next two sentences of the article | these rotation curves , derived from observations , were found to rise more slowly than those of hsb galaxies of the same luminosity , if the radii are measured in kpc . at the outermost measured point
, they were often still rising . |
6,117 | Suppose that you have an abstract for a scientific paper: it is widely believed that the carbonate@xmath0silicate cycle @xcite is the main agent - through volcanism - to trigger deglaciations by co@xmath1 greenhouse warming on earth and on earth - like planets when they get in frozen state .
here we use a 3d global climate model ( gcm ) to simulate the ability of planets initially completely frozen to escape from glaciation episodes by accumulating enough gaseous co@xmath1 .
the model includes co@xmath1 condensation and sublimation processes and the water cycle .
we find that planets with earth - like characteristics ( size , mass , obliquity , rotation rate , ... ) orbiting a sun - like star may never be able to escape from a glaciation era , if their orbital distance is greater than @xmath2 1.27 astronomical units ( flux @xmath3 847 w m@xmath4 , s@xmath5 @xmath3 0.62 ) , because co@xmath1 would condense at the poles here the cold traps forming permanent co@xmath1 ice caps .
this limits the amount of co@xmath1 in the atmosphere and thus its greenhouse effect .
furthermore , our results indicate that for ( 1 ) high rotation rates ( p@xmath624 h ) , ( 2 ) low obliquity ( [email protected]@xmath8 ) , ( 3 ) low background gas partial pressures ( @xmath91bar ) , and ( 4 ) high water ice albedo ( h@xmath1o [email protected] ) , this critical limit could occur for significantly lower equivalent distance ( or higher insolation ) . for each possible configuration
, we show that the amount of co@xmath1 that can be trapped in the polar caps depends on the efficiency of co@xmath1 ice to flow laterally as well as its graviational stability relative to subsurface water ice .
the flow of co@xmath1 ice from polar regions to the equator is mostly controlled by the bottom temperature , and hence by the internal heat flux of the planet .
we find that a frozen earth - like planet located at 1.30 au of a sun - like star could store as much as 1.5/4.5/15 bars of dry ice at the poles , for internal heat fluxes of 100/30/10 mw m@xmath4 .
....
And you have already written the first three sentences of the full article: there are geological evidence that earth had to face multiple episodes of global ( or quasi - global ) glaciation , at the end of the archean 2.45 - 2.22 gyrs ago and during the neoproterozoic era 710 and 650 myears ago @xcite .
it is widely believed that the carbonate@xmath0silicate cycle @xcite was the main agent to trigger deglaciations on past earth .
in particular , on a completely frozen planet , also called hard snowball , the weathering of co@xmath1 is stopped ; continuous volcanic outgassing builds up atmospheric co@xmath1 , which warms up the climate until liquid water is produced in the equatorial regions . by extension.
Please generate the next two sentences of the article | , this mechanism may be crucial to stabilize the climate of earth - like exoplanets .
it is even central for the definition of the classical habitable zone @xcite , which assumes that planets can build up co@xmath1 atmospheres ( as massive as wanted ) suitable for the stability of surface liquid water . |
6,118 | Suppose that you have an abstract for a scientific paper: we report on a detailed investigation of the high - energy @xmath0-ray emission from ngc1275 , a well - known radio galaxy hosted by a giant elliptical located at the center of the nearby perseus cluster . with the increased photon statistics , the center of the @xmath0-ray
emitting region is now measured to be separated by only @xmath1arcmin from the nucleus of ngc1275 , well within the @xmath2 confidence error circle with radius @xmath3arcmin . early _
fermi_-lat observations revealed a significant decade - timescale brightening of ngc1275 at gev photon energies , with a flux about seven times higher than the one implied by the upper limit from previous egret observations . with the accumulation of one - year of _ fermi_-lat all - sky - survey exposure , we now detect flux and spectral variations of this source on month timescales , as reported in this paper .
the average @xmath4100 mev @xmath0-ray spectrum of ngc1275 shows a possible deviation from a simple power - law shape , indicating a spectral cut - off around an observed photon energy of @xmath5 gev , with an average flux of @xmath6ph@xmath7s@xmath8 and a power - law photon index , @xmath9 .
the largest @xmath0-ray flaring event was observed in april may 2009 and was accompanied by significant spectral variability above @xmath10 gev .
the @xmath0-ray activity of ngc1275 during this flare can be described by a hysteresis behavior in the flux versus photon index plane .
the highest energy photon associated with the @xmath0-ray source was detected at the very end of the observation , with the observed energy of @xmath11gev and an angular separation of about @xmath12arcmin from the nucleus . in this paper
we present the details of the _ fermi_-lat data analysis , and briefly discuss the implications of the observed @xmath0-ray spectral evolution of ngc1275 in the context of @xmath0-ray blazar sources in general . .
And you have already written the first three sentences of the full article: with the successful launch of the _ fermi _ gamma - ray space telescope , we have a new opportunity to study the @xmath0-ray emission from different types of extragalactic sources not only blazars , but also radio galaxies and possibly other classes of active galactic nuclei ( agn ) with much improved sensitivity than previously available ( abdo et al .
2010a ) . during the initial all - sky survey performed during the first four months after its launch , the _ fermi _ large area telescope ( lat ) detected only two radio galaxies at high significance ( @xmath13 ) , namely ngc1275 ( abdo et al . 2009a
; hereafter paper - i ) and cena ( abdo et al ..
Please generate the next two sentences of the article | 2009b , 2009c ) .
more recently , the detection of mev / gev emission from yet another famous radio galaxy m87 , an established tev source , was reported based on ten - months of all - sky survey _ fermi_-lat data ( abdo et al . |
6,119 | Suppose that you have an abstract for a scientific paper: cluster galaxies moving through the intracluster medium ( icm ) are expected to lose some of their interstellar medium ( ism ) through ism - icm interactions .
we perform high resolution ( 40 pc ) three - dimensional hydrodynamical simulations of a galaxy undergoing ram pressure stripping including radiative cooling in order to investigate stripping of a multiphase medium .
the clumpy , multiphase ism is self - consistently produced by the inclusion of radiative cooling , and spans six orders of magnitude in gas density .
we find no large variations in the amount of gas lost whether or not cooling is involved , although the gas in the multiphase galaxy is stripped more quickly and to a smaller radius .
we also see significant differences in the morphology of the stripped disks .
this occurs because the multiphase medium naturally includes high density clouds set inside regions of lower density .
we find that the lower density gas is stripped quickly from any radius of the galaxy , and the higher density gas can then be ablated .
if high density clouds survive , through interaction with the icm they lose enough angular momentum to drift towards the center of the galaxy where they are no longer stripped .
finally , we find that low ram pressure values compress gas into high density clouds that could lead to enhanced star formation , while high ram pressure leads to a smaller amount of high - density gas . .
And you have already written the first three sentences of the full article: it has long been known that a galaxy s environment has an impact on its morphology : spirals dominate in the field , and ellipticals and s0s dominate in dense cluster environments ( hubble & humason 1931 ) .
this has been quantified in the density - morphology relation ( oemler 1974 ; dressler 1980 ) , but this relation alone does not determine whether the cluster environment affects the formation or the evolution of galaxies . according to the butcher - oemler effect ,
clusters at z @xmath0 0.2 are bluer and contain more spirals than nearby clusters , indicating that cluster environments may be correlated with the evolution of galaxies from spirals to earlier types ( butcher & oemler 1978 ) ..
Please generate the next two sentences of the article | more recently , by examining a specific merging cluster , tran et al .
( 2005 ) presents a strong relationship between the butcher - oemler effect and infalling galaxies . |
6,120 | Suppose that you have an abstract for a scientific paper: several models of minimum - bias hadronic interactions at ultra - high energy that have been used for calculations of air showers share essential common features . in this talk
i review these common elements and discuss some consequences .
i concentrate on properties of hadron - nucleus interactions , and i use mean depth of shower maximum as a function of primary energy to illustrate my main points .
i will contrast these models with models that use a more naive treatment of hadronic interactions in nuclei but which have been successfully used to interpret measurements of depth of shower maximum .
= 16.5 cm = -.5 cm = 0.1 cm = -1 cm .
And you have already written the first three sentences of the full article: the spectrum of cosmic rays extends more than five orders of magnitude beyond the highest energy at which it has been possible so far to observe the primaries directly with experiments on balloons or spacecraft . in this
energy range the spectrum has at least two features , the knee between @xmath0 and @xmath1 ev and the ankle between @xmath2 and @xmath3 ev .
the knee may be associated with a transition between different classes of galactic cosmic rays ( or with a feature of propagation of galactic cosmic rays ) and the ankle with a transition from galactic to extra - galactic origin of the particles but these are only plausible conjectures . in order to understand the implications of these features for the origin of the high - energy particles it is necessary to measure the relative contribution of the different groups of nuclei ..
Please generate the next two sentences of the article | this must be done with large ground - based air - shower experiments in order to achieve sufficient exposure to collect a large sample of high - energy events . because of the indirect nature of air shower experiments and the problems of fluctuations superimposed on a steeply falling energy spectrum , progress toward the goal of measuring the primary composition at high energy has been slow and difficult .
new experiments with better resolution , coupled with a better understanding of the hadronic interaction models used to interpret the data , show promise for improving the situation . the current status is summarized very nicely in the review of kalmykov and khristiansen @xcite . concerning the knee region , |
6,121 | Suppose that you have an abstract for a scientific paper: we study a three - mode hamiltonian modelling a heteronuclear molecular bose
einstein condensate .
two modes are associated with two distinguishable atomic constituents , which can combine to form a molecule represented by the third mode . beginning with a semi - classical analogue of the model , we conduct an analysis to determine the phase space fixed points of the system .
bifurcations of the fixed points naturally separate the coupling parameter space into different regions .
two distinct scenarios are found , dependent on whether the imbalance between the number operators for the atomic modes is zero or non - zero .
this result suggests the ground - state properties of the model exhibit an unusual sensitivity on the atomic imbalance .
we then test this finding for the quantum mechanical model .
specifically we use bethe ansatz methods , ground - state expectation values , the character of the quantum dynamics , and ground - state wavefunction overlaps to clarify the nature of the ground - state phases .
the character of the transition is smoothed due to quantum fluctuations , but we may nonetheless identify the emergence of a quantum phase boundary in the limit of zero atomic imbalance .
pacs : 02.30.ik , 03.65.sq , 03.75.nt .
And you have already written the first three sentences of the full article: the achievement of producing bose einstein condenstates with ultracold dilute gases of atoms has seen a wealth of theoretical and experimental activity . one enticing prospect of bose - einstein condensates is that they may allow for a better understanding of the interface between classical and quantum mechnics , through the possibility of macroscopic schrdinger cat states @xcite and macroscopic quantum tunneling @xcite .
another intriguing field of study is the chemistry of bose - einstein condensates , where the atomic constituents may form molecules through feshbach resonances @xcite or photoassociation @xcite . a novel feature of a molecular bose
einstein condensate is that the atomic and molecular states can exist as a superposition @xcite , providing a chemical analogue of a schrdinger cat state . in cases where the molecules are heteronuclear.
Please generate the next two sentences of the article | , the presence of a permanent electric dipole moment also opens the possibility for manipulating the condensate through electrostatic forces @xcite .
since systems of bose einstein condensates exist at ultracold temperatures , it is to be expected that significant insights into their behaviour can be obtained from studying their ground - state properties . from a general theoretical perspective |
6,122 | Suppose that you have an abstract for a scientific paper: the standard model for molecular recognition of an odorant is that receptor sites discriminate by molecular geometry as evidenced that two chiral molecules may smell very differently .
however , recent studies of isotopically labeled olfactants indicate that there may be a molecular vibration - sensing component to olfactory reception , specifically in the spectral region around 2300 @xmath0 . here
we present a donor - bridge - acceptor model for olfaction which attempts to explain this effect .
our model , based upon accurate quantum chemical calculations of the olfactant ( bridge ) in its neutral and ionized states , posits that internal modes of the olfactant are excited impulsively during hole transfer from a donor to acceptor site on the receptor , specifically those modes that are resonant with the tunneling gap . by projecting the impulsive force onto the internal modes
, we can determine which modes are excited at a given value of the donor - acceptor tunneling gap . only those modes resonant with the tunneling gap and are impulsively excited will give a significant contribution to the inelastic transfer rate . using acetophenone as a test case , our model and experiments on _ d. melanogaster
_ suggest that isotopomers of a given olfactant give rise to different odorant qualities .
these results support the notion that inelastic scattering effects may play a role in discriminating between isotopomers but that this is not a general spectroscopic effect . .
And you have already written the first three sentences of the full article: the general model for detection is that the response is triggered by the transfer of an electron from a donor ( d ) to an acceptor ( a ) within the receptor site by the presence of an olfactant molecule that provides a bridge between the two . in the absence of the odorant ,
the distance between d and a is too great and electron transfer is inefficient .
placing an olfactant ( b ) between the two allows the electron transfer to occur either as a single coherent scattering event from d to a , or as a sequence of two incoherent hops , first from d to b then from b to a. this simple model is consistent with the standard `` swipe - card '' model for odor detection since implicit in this is that b must fit into some sort of pocket and be in a correct alignment between d and a in order for the charge transfer process to occur ..
Please generate the next two sentences of the article | an interesting extension to this paradigm is that molecular shape may not be the sole deciding factor in scent recognition .
indeed , it has been observed recently that fruit flies ( _ d . melanogaster _ ) can navely discriminate between several isotopomers that have deuteriums substituted for hydrogen@xcite . |
6,123 | Suppose that you have an abstract for a scientific paper: about two - thirds of present - day , large galaxies are spirals such as the milky way or andromeda , but the way their thin rotating disks formed remains uncertain .
observations have revealed that half of their progenitors , six billion years ago , had peculiar morphologies and/or kinematics , which exclude them from the hubble sequence .
major mergers , i.e. , fusions between galaxies of similar mass , are found to be the likeliest driver for such strong peculiarities . however , thin disks are fragile and easily destroyed by such violent collisions , which creates a critical tension between the observed fraction of thin disks and their survival within the @xmath0-cdm paradigm . here
we show that the observed high occurrence of mergers amongst their progenitors is only apparent and is resolved when using morpho - kinematic observations which are sensitive to all the phases of the merging process .
this provides an original way of narrowing down observational estimates of the galaxy merger rate and leads to a perfect match with predictions by state - of - the - art @xmath0-cdm semi - empirical models with no particular fine - tuning needed .
these results imply that half of local thin disks do not survive but are actually rebuilt after a gas - rich major merger occurring in the past nine billion years , i.e. , two - thirds of the lifetime of the universe .
this emphasizes the need to study how thin disks can form in halos with a more active merger history than previously considered , and to investigate what is the origin of the gas reservoir from which local disks would reform . .
And you have already written the first three sentences of the full article: over the past years , observations and theory have been progressing significantly in understanding how the first large disk galaxies could form .
near - infrared ( rest - frame optical ) imaging from the hst reveals that , while @xmath140% of z@xmath11 - 3 most massive ( i.e. , @xmath2 ) galaxies are relatively compact and quiescent , @xmath160% of them are actively forming stars and show quite extended stellar structures ( @xcite ; see also @xcite ) . in a larger range of mass (
i.e. , @xmath110@xmath3 - 10@xmath4 ) , @xcite suggested that the stellar phase of [email protected] - 3.6 galaxies is probably distributed as triaxial ellipsoids rather than thick disks ..
Please generate the next two sentences of the article | integral field spectroscopy now routinely provides us with spatially - resolved kinematics of the sub - population of z@xmath11 - 3 emission line galaxies @xcite . actively forming galaxies at these epochs reveal a relatively balanced mix of obvious ( major ) mergers , relatively compact dispersion - supported objects , and rotating extended structures , all being much more turbulent in their gaseous phase compared to local galaxies @xcite . on the theoretical side ,
cosmological simulations have predicted that streams of cold gas would occur in the halos in which these galaxies are expected to inhabit @xcite . |
6,124 | Suppose that you have an abstract for a scientific paper: we propose measurement - based quantum computation ( mbqc ) as a quantum mechanical toy model for spacetime . within this framework
, we discuss the constraints on possible temporal orders enforced by certain symmetries present in every mbqc .
we provide a classification for all mbqc temporal relations compatible with a given initial quantum state and measurement setting , in terms of a matroid .
further , we find a symmetry transformation related to local complementation that leaves the temporal relations invariant . after light cones and closed time - like curves have previously been found to have mbqc counterparts , we identify event horizons as a third piece of the phenomenology of general relativity that has an analogue in mbqc . .
And you have already written the first three sentences of the full article: unifying quantum mechanics @xcite-@xcite with general relativity @xcite is a major open problem in physics .
after the unification of quantum mechanics and special relativity has been accomplished @xcite , in the resulting relativistic quantum field theories @xcite - @xcite , spacetime and quantum - mechanical degrees of freedom are still treated on a separate footing .
for example , the electromagnetic , weak and strong forces are described as being mediated by particles , namely photons , @xmath0 and @xmath1-bosons , and gluons ..
Please generate the next two sentences of the article | an analogous consistent formulation of gravity has so far not succeeded . in order to overcome the schism between the theory of gravity on one side and quantum mechanics on the other
, one may therefore ask : is there an element in the structure of quantum mechanics that forces spacetime into existence ? |
6,125 | Suppose that you have an abstract for a scientific paper: the aim of this paper is to analyze the morris - shore ( ms ) transformation in the case of weak deviation of the condition for equal detunings . for this generalization of the ms transformation a perturbative solution
is derived .
some elements concerning the general solution of the ms transformation are also discussed . .
And you have already written the first three sentences of the full article: the dynamics of a two - state quantum system resulting from the action of a resonant external pulse of precise temporal area is a classical example in quantum mechanics .
this simple two - state quantum system has an interesting theoretical extension , from a nondegenerate two - level quantum system ( where only two two quantum states /ground and excited/ are available ) , to one with a degenerate ground level and a degenerate excited level .
these physical systems can be found at isolated atoms and molecules , where the states of well defined angular momentum j , due to the rotational symmetry produces a degeneracy of 2j+1 magnetic sublevels . for correct description of laser - induced transitions between quantum states with defined angular momentum , one must also incorporate several magnetic sublevels ( labeled by m ) , that may serve as a possible initial states ..
Please generate the next two sentences of the article | hence each of these magnetic sublevels have a laser - driven excitation dynamic into to set of excited magnetic sublevels .
other source of multilevel systems can be the systems , whose mathematical description uses the usual rotating - wave approximation ( rwa ) . within the rwa the degeneracies can also be found for more general multistate quantum systems . to handle such multilevel systems , in 1983 morris and shore have introduced a coordinate transformation with the general property that could factorize the dynamic of any two degenerate sets of quantum states , to an equivalent description involving only independent uncoupled pairs of equations . generally , the morris - shore ( ms ) transformation is able to reduces the coherent quantum dynamics of a coupled degenerate two - level system to a set of independent nondegenerate two - state systems and a set of uncoupled states . |
6,126 | Suppose that you have an abstract for a scientific paper: we present a proof - of - principle experiment demonstrating measurement of the collectibility , a nonlinear entanglement witness proposed by rudnicki _
et al . _ [ phys .
rev .
lett . * 107 * , 150502 ( 2011 ) ] .
this entanglement witness works for both mixed and pure two - qubit states . in the later case
it can be used to measure entanglement in terms of the negativity .
we measured the collectibility for three distinct classes of photonic polarization - encoded two - qubit states , i.e. , maximally entangled , separable and maximally mixed states .
we demonstrate that the measurement procedure is feasible and robust against typical experimental shortcomings such as imperfect two - photon indistinguishability . .
And you have already written the first three sentences of the full article: quantum entanglement is a particularly intriguing phenomenon @xcite . since its conception in the famous epr paper @xcite
, it has received a great deal of interest . over the years
both theoretical and experimental research was dedicated to its investigation @xcite . two distinct strategies are usually applied to quantum entanglement detection and quantification ..
Please generate the next two sentences of the article | the first approach to entanglement characterization is based on quantum state tomography and density matrix estimation @xcite . knowing the state s density matrix , it is possible to apply various entanglement criteria and entanglement measures ( e.g. , the peres - horodecki citerion @xcite ) . performing full state tomography is however a lengthy procedure since the number of required measurements grows exponentially with the dimension of hilbert space .
the second strategy is based on so - called entanglement witnesses ( ew ) . measuring a simple linear ew |
6,127 | Suppose that you have an abstract for a scientific paper: the illuminated dusty surface of mars acts like a gas pump .
it is driven by thermal creep at low pressure within the soil . in the top soil layer
this gas flow has to be sustained by a pressure gradient .
this is equivalent to a lifting force on the dust grains .
the top layer is therefore under tension which reduces the threshold wind speed for saltation .
we carried out laboratory experiments to quantify the thickness of this activated layer .
we use basalt with an average particle size of 67 @xmath0 m . we find a depth of the active layer of 100 to 200 @xmath1 .
scaled to mars the activation will reduce threshold wind speeds for saltation by about 10% . .
And you have already written the first three sentences of the full article: it is a long standing problem how to move particles on the martian surface .
the most prominent mechanism is wind in analogy to transport of sand on earth .
numerous work has been carried out on this in the past especially in wind tunnel experiments @xcite ..
Please generate the next two sentences of the article | recent images of the hirise camera onboard the mars reconnaissance orbiter show that martian sand transport is still active .
they find dunes which travel several meters in a few years @xcite . |
6,128 | Suppose that you have an abstract for a scientific paper: it is generally acknowledged that the mass loss of asymptotic giant branch ( agb ) stars undergoes variations on different time scales .
we constructed models for the dust envelopes for a sample of agb stars to assess whether mass - loss variations influence the spectral energy distribution ( sed ) . to constrain the variability , extra observations at millimetre wavelengths ( @xmath0 mm ) were acquired . from the analysis of the dust models , two indications for the presence of mass - loss variations can be found , being ( @xmath1 ) a dust temperature at the inner boundary of the dust envelope that is far below the dust condensation temperature and ( @xmath2 ) an altered density distribution with respect to @xmath3 resulting from a constant mass - loss rate . for 5 out of the 18
studied sources a two - component model of the envelope is required , consisting of an inner region with a constant mass - loss rate and an outer region with a less steep density distribution . for one source an outer region with a steeper density distribution was found .
moreover , in a search for time variability in our data set at 1.2 mm , we found that wx psc shows a large relative time variation of @xmath4% which might partially be caused by variable molecular line emission .
[ firstpage ] stars : agb and post - agb stars : mass - loss stars : variables : other radio continuum : stars . .
And you have already written the first three sentences of the full article: when low- and intermediate mass stars enter the agb phase at the end of their lives , the mass - loss rate exceeds the nuclear burning rate and so dominates the subsequent evolution . in this process , a circumstellar envelope ( cse ) of gas and dust is formed which expands at a rate of about @xmath5km@xmath6 ( see for example @xcite ) .
the agb mass loss undergoes variations on different time scales .
the mass loss gradually increases over a time scale of several hundred thousands of years to reach a maximum on the tip of the thermally pulsing - agb @xcite ..
Please generate the next two sentences of the article | the pulsations of the central star cause variations over several hundreds of days .
strong variations in the mass - loss rate , probably related to thermal pulses occurring every @xmath7-@xmath5 @xmath8yr @xcite , can lead to the formation of circumstellar detached shells . |
6,129 | Suppose that you have an abstract for a scientific paper: we study properties of _ quantum strategies _ , which are complete specifications of a given party s actions in any multiple - round interaction involving the exchange of quantum information with one or more other parties .
in particular , we focus on a representation of quantum strategies that generalizes the choi - jamiokowski representation of quantum operations .
this new representation associates with each strategy a positive semidefinite operator acting only on the tensor product of its input and output spaces .
various facts about such representations are established , and two applications are discussed : the first is a new and conceptually simple proof of kitaev s lower bound for strong coin - flipping , and the second is a proof of the exact characterization @xmath0 of the class of problems having quantum refereed games . .
And you have already written the first three sentences of the full article: the theory of games provides a general structure within which both cooperation and competition among independent entities may be modeled , and provides powerful tools for analyzing these models .
applications of this theory have fundamental importance in many areas of science .
this paper considers games in which the players may exchange and process quantum information ..
Please generate the next two sentences of the article | we focus on competitive games , and within this context the types of games we consider are very general .
for instance , they allow multiple rounds of interaction among the players involved , and place no restrictions on players strategies beyond those imposed by the theory of quantum information . while classical games can be viewed as a special case of quantum games , it is important to stress that there are fundamental differences between general quantum games and classical games . |
6,130 | Suppose that you have an abstract for a scientific paper: we address the decoherence of a localized electron spin in an external magnetic field due to the hyperfine interaction with a lattice of nuclear spins . using a completely non - perturbative method ,
rigorous bounds on the @xmath0 and @xmath1 coherence times for the electron spin are provided .
it is shown that for magnetic fields @xmath2 greater than some critical field @xmath3 ( @xmath4 for the systems studied here ) , the @xmath5-polarization of the electron spin can not relax , and hence @xmath0 is infinite . however , even at high fields dephasing can still occur .
we provide a lower bound on the @xmath1 coherence time that explicitly takes into account the effects of a spin echo pulse sequence . .
And you have already written the first three sentences of the full article: isolated electron spin systems are of great interest because of their potential application as coherent quantum memory in novel solid state devices@xcite .
several quantum computation proposals make use of electron spins , either as the qubits themselves or as intrinsic components of one- and two - qubit gates @xcite .
furthermore , experimental efforts are just now succeeding at measuring single electron spin relaxation times @xcite ..
Please generate the next two sentences of the article | unfortunately , the exponential size of the hilbert space of these spin systems and the variety of channels for decoherence makes an exact analysis of spin dynamics virtually impossible ( without the use of a quantum computer)@xcite . as a result , it is often necessary to resort to approximations or perturbative treatments to address the timescale of electron spin decoherence , even using a simplified hamiltonian .
because approximations are inevitable , it is important to know which of these can be rigorously justified . in particular |
6,131 | Suppose that you have an abstract for a scientific paper: if a supermassive black hole has some material orbiting around it at close to its innermost stable circular orbit ( isco ) , then , when it plunges into a second supermassive black hole , the orbiting material has a velocity dispersion of order of speed of light about the orbital velocity of its host black hole .
it becomes plausible that some of the orbiting material will be catapulted " to the negative - energy ergosphere orbits of the second black hole at the plunge .
this may provide an astrophysically plausible way to extract energy from the black hole , originally suggested by penrose .
= 1 .
And you have already written the first three sentences of the full article: * b72 hereafter ) show that one need an extra @xmath0 relative velocity boost after the plunge in order for the inbound debris to reach the ergosphere negative - energy orbits , to ultimately extract energy from the negative - energy orbits to be carried away by the outbound debris .
note that , while for a kerr black hole the apparent " radii of the event horizon , the photon orbit and and isco ( @xmath1 ) on a prograde orbit are the same in the boyer - lindquist coordinates , they are separate in proper coordinates and their energies are distinctly different . for example , for a kerr black hole , the orbital velocity at isco is @xmath2 ( not @xmath3 ) and the minimum energy of a plunge orbit that results from decay of a bound stable orbit is @xmath4 ( where @xmath5 is the mass of the orbiting particle ) .
thus , in order to get to the negative - energy ergosphere orbits , the orbiting particle at isco need to cross over this velocity gap of @xmath6 ..
Please generate the next two sentences of the article | this condition was deemed to be astrophysically unlikely ( b72 ) .
we suggest here that , when two black holes merge , if one or both have orbital material at close to their respective isco , then some of the orbital material may be able to jump " over this velocity gap of @xmath6 to land in the ergosphere negative - energy orbits , while portion of the orbiting material that escapes may be able to extract energy from the black hole via the @xcite process at the expense of the rotation of the black hole @xcite . |
6,132 | Suppose that you have an abstract for a scientific paper: traveling wave solutions of degenerate coupled @xmath0-kdv equations are studied . due to symmetry reduction
these equations reduce to one ode , @xmath1 where @xmath2 is a polynomial function of @xmath3 of degree @xmath4 , where @xmath5 in this work . here
@xmath0 is the number of coupled fields .
there is no known method to solve such ordinary differential equations when @xmath5 . for this purpose ,
we introduce two different type of methods to solve the reduced equation and apply these methods to degenerate three - coupled kdv equation .
one of the methods uses the chebyshev s theorem . in this case
we find several solutions some of which may correspond to solitary waves .
the second method is a kind of factorizing the polynomial @xmath2 as a product of lower degree polynomials .
each part of this product is assumed to satisfy different odes .
+ * keywords : * traveling wave solution , degenerate kdv system , chebyshev s theorem , alternative method .
[ section ] [ section ] [ section ] [ section ] [ section ] .
And you have already written the first three sentences of the full article: the system of degenerate coupled multi - field kdv equations is given as @xcite-@xcite @xmath6 where @xmath7 and @xmath8 . in @xcite-@xcite , it was shown that this system is also a degenerate kdv system of rank one . in a previous work @xcite we focused on the equation ( [ eqn1 ] ) for @xmath9 .
we reduced this equation into an ode @xmath10 where @xmath11 is a polynomial function of degree four .
we analyzed all possible cases about the zeros of @xmath11 . due to this analysis we determined the cases when the solution is periodic or solitary . when the polynomial has one double @xmath12 and two simple zeros @xmath13 , @xmath14 with @xmath15 , or one triple and one simple zeros , the solution is solitary ..
Please generate the next two sentences of the article | other cases give periodic or non - real solutions . by using the jacobi elliptic functions
@xcite , we obtained periodic solutions and all solitary wave solutions which rapidly decay to some constants , explicitly . |
6,133 | Suppose that you have an abstract for a scientific paper: we analyze _ citeulike _ , an online collaborative tagging system where users bookmark and annotate scientific papers . such a system can be naturally represented as a tripartite graph whose nodes represent papers , users and tags connected by individual tag assignments .
the semantics of tags is studied here , in order to uncover the hidden relationships between tags .
we find that the clustering coefficient reflects the semantical patterns among tags , providing useful ideas for the designing of more efficient methods of data classification and spam detection .. the recent development of the world wide web is characterized by a growing number of online social communities . in many such cases ,
individuals provide bits of information - about either their tastes , opinions or interests - and software applications gather and organize them into a database , allowing the browsing of the whole information collected so .
a class of such collaborative systems focusses on collecting users online bookmarks with either a general approach or a more specialized one . in particular , some websites have been recently born to store user generated scientific bibliographies . in these systems ,
the elementary contribution , the `` post '' , is made of three ingredients : a user , an article and an annotation of it by a number of tags chosen by users . in exchange for this voluntary contribution
, a user can browse others bibliographies and annotations .
tags are an alternative classification method with respect to traditional taxonomies , where items belong to `` taxa '' represented as a tree like set of categories : here , each category contains in turn a number of more specialized sub categories , and so on until the desired resolution of classification is been reached . instead , in tagging systems items are tagged by users characterized by diverse tagging strategies depending on a number of individual variables .
the set of tag resource relations in such a community is called a `` folksonomy ''....
And you have already written the first three sentences of the full article: 99 heyman p and garcia - molina h 2006 collaborative creation of communal hierarchical taxonomies in social tagging systems _ technical report infolab 2006 - 10 .
department of computer science , stanford university , stanford , ca , usa _
schmitz c , grahl m , hotho a , stumme g , cattuto c , baldassarri a , loreto v and servedio vdp 2007 network properties of folksonomies _ proceedings of the sixteenth international world wide web conference ( www2007 ) _.
Please generate the next two sentences of the article | |
6,134 | Suppose that you have an abstract for a scientific paper: we give a characterization of hypercyclic using ( locally hypercyclic ) of semigroup @xmath0 of affine maps of @xmath1 .
we prove the existence of a @xmath0-invariant open subset of @xmath1 in which any locally hypercyclic orbit is dense in @xmath1 . .
And you have already written the first three sentences of the full article: let @xmath2 be the set of all square matrices of order @xmath3 with entries in @xmath4 and @xmath5 be the group of all invertible matrices of @xmath2 .
a map @xmath6 is called an affine map if there exist @xmath7 and @xmath8 such that @xmath9 , @xmath10 .
we denote @xmath11 , we call @xmath12 the _ linear part _ of @xmath13 . the map @xmath13 is invertible if @xmath14 ..
Please generate the next two sentences of the article | denote by @xmath15 the vector space of all affine maps on @xmath1 and @xmath16 the group of all invertible affine maps of @xmath17 .
let @xmath0 be an abelian affine sub - semigroup of @xmath18 . for a vector @xmath19 |
6,135 | Suppose that you have an abstract for a scientific paper: we present the results of the first analysis of high dispersion spectra of four red hb stars in the metal rich globular cluster ngc 6528 , located in baade s window .
we find that the mean [ fe / h ] for ngc 6528 is @xmath0 dex ( error of the mean ) , with a star - to - star scatter of @xmath1 dex ( 4 stars ) , although the total error is likely to be larger ( @xmath2 dex ) due to systematic errors related to the effective temperature scale and to model atmospheres .
this metallicity is somewhat larger than both the mean abundance in the galactic bulge found by mcwilliam & rich ( 1994 ) and that found in our previous paper for ngc 6553 .
however , we find that the spectra of clump stars in ngc 6528 and ngc 6553 are very similar each other , the slightly different metal abundances found being possibly due to the different atmospheric parameters adopted in the two analyses .
since the present analysis is based on higher quality material , we propose to revise our previous published metal abundance for ngc 6553 to [ fe / h]=@xmath3 . for ngc 6528
we find excesses for the @xmath4-process elements si and ca ( [ si / fe]=+0.4 and [ ca / fe]=+0.2 ) , whereas mn is found to be underabundant ( [ mn / fe][email protected] ) .
we find a solar abundance of o ; however this is somewhat uncertain due to the dependence of the o abundance on the adopted atmospheric parameters and to coupling between c and o abundances in these cool , metal - rich stars .
finally , we find large na excesses ( [ na / fe]@xmath6 ) in all stars examined . .
And you have already written the first three sentences of the full article: the bulge is one of the major components of the milky way .
its integrated properties resemble those of giant ellipticals , which in turn are one of the dominant components of the universe .
however , in contrast to these distant environments , the relative proximity of the galactic bulge allows us to study individual stars in detail , and ( at least in some cases ) derive accurate abundances for the local version of old metal rich populations ..
Please generate the next two sentences of the article | this capability is very helpful in reconstructing the history of formation , still quite controversial , of these very important constituents of the universe .
unfortunately , owing to the rather large distance and to substantial interstellar absorption characteristic of the bulge , without a significant boost from microlensing , detailed abundance analyses of bulge stars have to be limited to the evolved population . |
6,136 | Suppose that you have an abstract for a scientific paper: in this paper , we present a method to generate continuous - variable - type entangled states between photons and atoms in atomic bose - einstein condensate ( bec ) .
the proposed method involves an atomic bec with three internal states , a weak quantized probe laser and a strong classical coupling laser , which form a three - level @xmath0-shaped bec system .
we consider a situation where the bec is in electromagnetically induced transparency ( eit ) with the coupling laser being much stronger than the probe laser . in this case
, the upper and intermediate levels are unpopulated , so that their adiabatic elimination enables an effective two - mode model involving only the atomic field at the lowest internal level and the quantized probe laser field .
atom - photon quantum entanglement is created through laser - atom and inter - atomic interactions , and two - photon detuning .
we show how to generate atom - photon entangled coherent states and entangled states between photon ( atom ) coherent states and atom-(photon- ) macroscopic quantum superposition ( mqs ) states , and between photon - mqs and atom - mqs states .
pacs number(s ) : 03.65.ta , 03.65.ud , 03.75.fi .
And you have already written the first three sentences of the full article: for decades , quantum entanglement has been the focus of much work in the foundations of quantum mechanics , being particularly associated with quantum nonseparability , the violation of bell s inequalities , and the so - called einstein - pololsky - rosen ( epr ) paradox . beyond this fundamental aspect ,
creating and manipulating of entangled states are essential for quantum information applications . among these applications are quantum computation @xcite , quantum teleportation @xcite , quantum dense coding @xcite , quantum cryptography @xcite , and quantum positioning and clock synchronization @xcite .
hence , quantum entanglement has been viewed as an essential resource for quantum information processing ..
Please generate the next two sentences of the article | recently much attention has been paid to continuous variable quantum information processing in which continuous - variable - type entangled pure states play a key role .
for instance , two - state entangled coherent states are used to realize efficient quantum computation @xcite and quantum teleportation @xcite . |
6,137 | Suppose that you have an abstract for a scientific paper: this dissertation reviews the standard model formalism as well as the lepton flavour violating ( lfv ) decay processes which cause its extension , known as the physics beyond the sm .
firstly , using the experimental bounds on three body lfv decays , the corrosponding bounds on two body lfv decays are reviewed .
the dynamical suppression of three body lfv decays due to momentum dependent couplings is also reviewed .
secondly , the role of the lfv decays to explain the lsnd excess is discussed in detail , for which the experimental bounds on three body lfv decays , i.e. @xmath0 are used to constraint the coupling @xmath1 , which is needed to calculate the anamolous muon decay @xmath2 . then comparing the effective coupling of anamolous muon decay to @xmath3@xcite , it is proved that lfv is not the correct hypothesis to explain the lsnd excess .
finally , lfv decays at loop order are studied in seesaw model of neutrino masses @xcite where the smallness of the seesaw neutrino mass may be naturally realized with @xmath4 ( mass of right - handed singlet neutrinos ) of order @xmath5 tev .
it is shown that the higgs mass of a new scalar doublet with lepton number @xmath6 needed in the model has to be larger than @xmath7 tev to get the branching ratio of @xmath0 to be consistant with the existing bound on @xmath8 .
this defeats the origional motivation of the model , namely that there is no physics beyond the tev energy scale .
tcilatex acknowledgements i am filled with the praise and glory to all mighty allah , the most merciful and benevolent , who created the uneverse , with ideas of beauty , symmetry and harmony , with regularity and without any chaos , and gave us the abilities to discover what he thought .
bless muhammad ( p.b.u.h ) the seal of the prophets and his pure and pious progeny .
first and the foremost , i want to express my immense gratitude to my worthy supervisor prof .
dr .
riazuddin for his professsional guidance and encouragement throughout this research....
And you have already written the first three sentences of the full article: the most fundamental element of physics is the reduction principle .
the large variety of macroscopic forms of matter can be traced back according to this principle , to a few microscopic constituents which interact by a small number of forces .
the reduction principle has provided a guide to unraveling of the structure of physics from the macroscopic world through atomic and nuclear physics to particle physics ..
Please generate the next two sentences of the article | the laws of nature are summarized in the standard model of the particle physics .
standard model is one of the successful model of the 20th century proposed by the glashow , weinberg and salam . |
6,138 | Suppose that you have an abstract for a scientific paper: we perform a multiwavelength study toward the snr g18.1 - 0.1 and nearby several hii regions ( infrared dust bubbles n21 and n22 , and the hii regions g018.149 - 00.283 and g18.197 - 00.181 ) .
our goal is to provide observational evidence supporting that massive stars usually born in clusters from the same molecular cloud , which then produce , along their evolution , different neighboring objects such as hii regions , interstellar bubbles and supernova remnants .
we suggest that the objects analysed in this work belong to a same complex located at the distance of about 4 kpc . using molecular data we inspected the interstellar medium toward this complex and from optical and x - ray observations we looked for ob - type stars in the region . analysing public @xmath0co j=10 data we found several molecular structures very likely related to the hii region / snr complex .
we suggest that the molecular gas is very likely being swept and shaped by the expansion of the hii regions . from spectroscopic optical observations obtained with the 2.15 m telescope at casleo , argentina , we discovered three o - type stars very likely exciting the bubbles n21 and n22 , and an uncatalogued hii region northward bubble n22 , respectively . also we found four b0 - 5 stars , one toward the bubble n22 and the others within the hii region g18.149 - 0.283 . by inspecting the chandra source catalog we found two point x - ray sources and we suggest that one of them is an early o - type star .
finally we inspected the large scale interstellar medium around this region .
we discovered a big molecular shell of about 70 pc @xmath1 28 pc in which the analysed complex appears to be located in its southern border .
[ firstpage ] ism : supernova remnants - ( ism : ) hii regions - ism : clouds - stars : massive .
And you have already written the first three sentences of the full article: m emission in blue and the mips-_spitzer _ 24 @xmath2 m emission is shown in green .
the objects analysed in this work are indicated . the arc feature in n22 and almost the whole interior of g18.149 - 0.283
are saturated in 24 @xmath2m.,width=362 ] nowadays it is well known that massive stars in our galaxy are born predominantly within the dense cores of giant molecular clouds ( for a thorough discussion of the star - formation theories see @xcite ) ..
Please generate the next two sentences of the article | they usually form and evolve in clusters , hence it is expectable to observe several hii regions in different evolutionary stages and probably also supernova remnants ( snrs ) in a same galactic neighborhood .
some examples of this spatial coincidence are the field toward w28 , with several snrs and hii regions ( e.g. @xcite ) , the snr w44 and the hii region g034.8 - 0.7 @xcite , the luminous blue variable ( lbv ) star candidate g24.73 + 0.69 , some hii regions and the snr g24.7 + 0.6 @xcite . |
6,139 | Suppose that you have an abstract for a scientific paper: we analyze the quantum process in which a cosmic string breaks in a de sitter ( ds ) background , and a pair of neutral or charged black holes is produced at the ends of the string . the energy to materialize and accelerate the pair comes from the positive cosmological constant and , in addition , from the string tension .
the compact saddle point solutions without conical singularities ( instantons ) or with conical singularities ( sub - maximal instantons ) that describe this process are constructed through the analytical continuation of the ds c - metric .
then , we explicitly compute the pair creation rate of the process .
in particular , we find the nucleation rate of a cosmic string in a ds background , and the probability that it breaks and a pair of black holes is produced .
finally we verify that , as occurs with pair production processes in other background fields , the pair creation rate of black holes is proportional to @xmath0 , where the gravitational entropy of the black hole , @xmath1 , is given by one quarter of the area of the horizons present in the saddle point solution that mediates the process . .
And you have already written the first three sentences of the full article: in nature there are few known processes that allow the production of black holes .
the best well - known is the gravitational collapse of a massive star or cluster of stars . due to fermionic degeneracy pressure these black holes
can not have a mass below the oppenheimer - volkoff limiting mass ( @xmath2 in recent calculations ) ..
Please generate the next two sentences of the article | another one is the quantum schwinger - like process of black hole pair creation in an external field .
these black holes can have planck dimensions and thus their evolution is ruled by quantum effects . |
6,140 | Suppose that you have an abstract for a scientific paper: i review the early history of photometric redshifts ; specify a working definition that encompasses a broader range of approaches than commonly adopted ; discuss the pros and cons of template fitting versus empirically - based techniques ; and summarize some past applications . despite its relatively long history ,
the technique of photometric redshifts remains far from being a mature tool .
areas needing development include the use of spatial structure , the incorporation of large redshift samples with multicolor photometry for empirical calibrations of redshift errors , and improved analysis tools that directly include redshift probability distributions rather than singular values .
photometric redshifts has not only undergone a recent revival it is also rapidly becoming a crucial tool of mainstream observational cosmology . .
And you have already written the first three sentences of the full article: photometric redshifts is a term that has received recent , wide - spread visibility and interest , though the use of multicolor photometry to estimate the redshifts of galaxies has a history that is relatively long . as of march 1999
, my search of the ads abstracts for the term `` photometric redshifts '' yielded only 9 papers ending in 1994 , with the first in 1982 , i.e. averaging less than one paper per year .
a sudden jump then occurs in 1995 with 6 papers , followed by 1996 with 7 , 1997 with 9 , and then another major jump to 35 papers in 1998 ..
Please generate the next two sentences of the article | the broad participation and range of topics of this workshop validate this surge in activity . among these papers ,
the earliest reference to the term `` photometric redshifts '' is found in the abstract of puschell et . |
6,141 | Suppose that you have an abstract for a scientific paper: single - spin asymmetry appears due to the interference of single and double gluon exchange between protons .
a heavy fermion model is used to describe the jet production in the interaction of gluon with the proton implying the further averaging over its mass . as usually in one - spin correlations ,
the imaginary part of the double gluon exchange amplitude play the relevant role .
the asymmetry in the inclusive set - up with the pion tagged in the fragmentation region of the polarized proton does not depend on the center of mass energy in the limits of its large values .
the lowest order radiative corrections to the polarized and unpolarized contributions to the differential cross sections are calculated in the leading logarithmical approximation . in general , a coefficient at logarithm of the ratio of cms energy to the pion mass depends on transversal momentum of the pion .
this ratio of the lowest order contribution to the asymmetry may be interpreted as the partial contribution to the odderon intercept .
the ratio of the relevant contributions in the unpolarized case can be associated with the partial contribution to the pomeron intercept .
the numerical results given for the model describe the jet as a heavy fermion decay fragments .
@xmath0 _ join institute for nuclear research , 141980 dubna , russia , + @xmath1 _ leningrad institute for nuclear physics , gatchina , russia _ _ .
And you have already written the first three sentences of the full article: let us consider the inclusive process of the pion creation in the fragmentation region of polarized proton at high energy proton - proton collisions @xmath2 where @xmath3 is the transversal to beam ( implied by cms ) axes spin of initial proton @xmath4 where @xmath5 is the energy fraction of pion , @xmath6 are the invariant masses of the jets , which we will assume to be of the order of nucleon mass @xmath7 .
we study the two jet kinematics with jets @xmath8 , @xmath9 moving along the initial hadron directions . the jet created by the transversely polarized proton
is supposed to contain the detected pion ..
Please generate the next two sentences of the article | moreover , we consider the case when its production is not related with the creation of nucleon resonances . in terms of pion transverse components
it corresponds to the condition @xmath10 |
6,142 | Suppose that you have an abstract for a scientific paper: this letter describes a completely - integrable system of yang - mills - higgs equations which generalizes the hitchin equations on a riemann surface to arbitrary @xmath0-dimensional complex manifolds .
the system arises as a dimensional reduction of a set of integrable yang - mills equations in @xmath1 real dimensions .
our integrable system implies other generalizations such as the simpson equations and the non - abelian seiberg - witten equations .
some simple solutions in the @xmath2 case are described . * msc : * 81t13 , 53c26 . *
keywords : * gauge theory , higgs , integrable system . .
And you have already written the first three sentences of the full article: this note concerns completely - integrable systems of yang - mills - higgs equations , and in particular those which may be viewed as higher - dimensional generalizations of the two - dimensional hitchin equations ( the self - duality equations on a riemann surface ) .
let us begin by briefly setting out the notation .
we denote local coordinates on @xmath3 by @xmath4 with @xmath5 . for simplicity.
Please generate the next two sentences of the article | we take the gauge group to be su(2 ) throughout .
a gauge potential @xmath6 takes values in the lie algebra @xmath7 , so each of @xmath8 is an anti - hermitian @xmath9 matrix . |
6,143 | Suppose that you have an abstract for a scientific paper: current theories of galaxy formation predict that spiral galaxies are embedded in a reservoir of hot gas .
this gas is able to cool onto the galaxy replenishing cold gas that is consumed by star formation .
estimates of the x - ray luminosity emitted in the cooling region suggest a bolometric luminosity of order @xmath0 in massive systems .
we have used rosat pspc data to search for extended x - ray emission from the haloes of three nearby , massive , late - type galaxies : ngc 2841 , ngc 4594 and ngc 5529 .
we infer 95% upper limits on the bolometric x - ray luminosities of the haloes of ngc 2841 , ngc 4594 and ngc 5529 of 0.4 , 1.2 and 3.8 @xmath1 respectively .
thus , the true luminosity lies well below the straightforward theoretical prediction .
we discuss this discrepancy and suggest a number of ways in which the theoretical model might be brought into agreement with the observational results .
a possible solution is that the gravitational potentials of these galaxies dark matter haloes are weaker than assumed in the current model .
alternatively , the present day accretion may be substantially less than is required on average to build the disk over the hubble time .
our results are , however , based on only three galaxies , none of which is ideal for this kind of study . a larger data set is required to explore this important problem further
. cooling flows - x - rays : galaxies - galaxies : formation - galaxies : ngc 2841 , ngc 4594 , ngc 5529 .
And you have already written the first three sentences of the full article: in models of galaxy formation by hierarchical clustering , the disks of spiral galaxies form by late accretion of gas which cools from an extended reservoir around the galaxy . in these models disks
are still expected to be growing at the present day .
such models have been very successful in accounting for properties of galaxies at optical and infrared wavelengths ( see , for example , kauffmann et al ..
Please generate the next two sentences of the article | 1993 , cole et al .
1994 , baugh , cole & frenk 1996 , kauffmann et al . 1999 ) . |
6,144 | Suppose that you have an abstract for a scientific paper: electronic structures of carbides with the rocksalt structure were calculated by full potential electronic codes solving the kohn - sham equation .
bonding characters were analyzed by constructing tight - binding hamiltonian based on maximally - localized wannier functions .
it was found that the cations in these compounds act as an electron provider and the frame is formed by the carbon atoms .
the electronic states in the vicinity of the fermi level are mainly from the p - orbitals of c. pressure and doping are two efficient ways to tune the magnetic and electronic properties of these compounds .
it turns out that a spin gapless semiconductor can be obtained by applying hydrostatic pressure up to tens of gigapascal .
higher pressure induced an insulator to metal transition because of band broadening .
compounds of ia group ( na , k , rb , cs ) were magnetic semiconductor at ambient conditions .
alloying with iia elements decrease the magnetic moment according to the law of @xmath0 , where @xmath1 is the relative atomic ratio of the iia elements to the ia ones .
the behaviors of the compounds under the pressure and the doping effects can be understood by a rigid band model . .
And you have already written the first three sentences of the full article: magnetic materials are essential for modern technology . up to date ,
most used magnetic materials involve elements with partially filled d or f - orbitals , like transitional metals , rare earth metals and their compounds .
magnetic ordering in these compounds originates from the localization of the electrons so that the kinetic energy can be minimized ..
Please generate the next two sentences of the article | this is the result of competitions between the kinetic energy and the exchange splitting .
the former favors nonmagnetic state while the latter is the source of spin polarization . |
6,145 | Suppose that you have an abstract for a scientific paper: in this paper , an exact bitwise map ( maximum a posteriori ) estimation algorithm for group testing problems is presented .
we assume a simplest non - adaptive group testing scenario including @xmath0-objects with binary status and @xmath1-disjunctive tests .
if a group contains a positive object , the test result for the group is assumed to be one ; otherwise , the test result becomes zero .
our inference problem is to evaluate the posterior probabilities of the objects from the observation of @xmath1-test results and from our knowledge on the prior probabilities for objects .
if the size of each group is bounded by a constant , a naive inference algorithm requires @xmath2-time for computing the posterior probabilities for objects .
our algorithm runs with @xmath3-time , which is exponentially faster than the naive inference algorithm under a common situation with @xmath4 .
the heart of the algorithm is the _ dual expression _ of the posterior values .
the derivation of the dual expression can be naturally described based on a holographic transformation to the normal factor graph ( nfg ) representing the inference problem . in order to handle or constraints in the nfg
, we introduce a novel holographic transformation that converts an or function to a function similar to an equal function . .
And you have already written the first three sentences of the full article: graphical models , such as factor graphs and normal factor graphs @xcite @xcite , can provide a concise description of the probabilistic assumption of an inference problem and they are indispensable for analyzing message passing inference algorithms such as bp ( belief propagation ) .
for example , the relationship between `` codes and graphs '' is one of key concepts of modern coding theory .
al - bashabsheh and mao @xcite recently shed a new light to normal factor graphs ..
Please generate the next two sentences of the article | they clearly showed that _ holographic transformations _ to normal factor graphs are versatile tools for deriving non - trivial identities on the partition function of a normal factor graph @xcite .
a holographic transformation is a local graphical transformation that preserves the partition function . |
6,146 | Suppose that you have an abstract for a scientific paper: the jupiter - family comet 103p / hartley 2 ( 103p ) was the target of the nasa epoxi mission .
in support of this mission , we conducted observations from radio to submillimeter wavelengths of comet 103p in the three weeks preceding the spacecraft rendezvous on ut 2010 november 4.58 .
this time period included the passage at perihelion and the closest approach of the comet to the earth .
here we report detections of hcn , @xmath0 , cs , and oh and upper limits for hnc and dcn towards 103p , using the arizona radio observatory kitt peak 12 m telescope ( aro 12 m ) and submillimeter telescope ( smt ) , the james clerk maxwell telescope ( jcmt ) and the greenbank telescope ( gbt ) . the water production rate , @xmath1 = ( 0.67 - 1.07 ) @xmath2 @xmath3 @xmath4 , was determined from the gbt oh data . from the average abundance ratios of hcn and @xmath0 relative to water ( 0.13 @xmath5 0.03 @xmath6 and 0.14 @xmath5 0.03 @xmath6 , respectively ) , we conclude that @xmath0 is depleted and hcn is normal with respect to typically - observed cometary mixing ratios .
however , the abundance ratio of hcn with water shows a large diversity with time . using the jcmt data we measured an upper limit for the dcn / hcn ratio @xmath70.01 .
consecutive observations of @xmath8-@xmath0 and @xmath9-@xmath0 on november 2 ( from data obtained at the jcmt ) , allowed us to derive an @xmath10 ratio ( opr ) @xmath11 2.12 @xmath5 0.59 ( 1@xmath12 ) , corresponding to @xmath13 @xmath14 8 k ( 2@xmath12 ) . .
And you have already written the first three sentences of the full article: comets are probably the least - altered bodies in the solar system @xcite . as such
, they can provide key insights into physical and chemical processes occurring during its origin and earliest evolutionary epochs , including the origin of long - period and short period comets @xcite and the formation and composition of planets @xcite . by studying comets from different reservoirs we can probe the different environments in which they formed and
also better understand their role in initiating prebiotic chemistry on the early earth through delivery of water and organic matter by cometary impacts @xcite ..
Please generate the next two sentences of the article | comets are primarily located in two distinct reservoirs of the solar system : the oort cloud and the kuiper belt .
the oort cloud is a source of long - period comets and ( probably ) halley - type comets @xcite . |
6,147 | Suppose that you have an abstract for a scientific paper: we have resolved kelu-1 into a binary system with a separation of @xmath0290 mas using the laser guide star adaptive optics system on the keck ii telescope . we have also re - analyzed a 1998 hst observation of kelu-1 and find that the observed psf is best fit by a binary object separated by 45 mas .
observations on multiple epochs confirm the two objects share a common proper motion and clearly demonstrate the first evidence of orbital motion .
kelu-1b is fainter than kelu-1a by [email protected] magnitudes in the @xmath2 filter and [email protected] magnitudes in the @xmath3 filter .
we derive spectral types of l2@xmath11 and l3.5@xmath11 for kelu-1a and b , respectively .
the separation of flux into the two components rectifies kelu-1 s over - luminosity problem that has been known for quite some time . given the available data we are able to constrain the inclination of the system to @xmath481@xmath5 and the orbital period to @xmath640 years . .
And you have already written the first three sentences of the full article: l dwarfs are a class of objects with spectral types cooler than the latest m dwarfs @xcite .
their population consists of both substellar ( i.e. brown dwarfs ) and stellar mass objects , with the brown dwarfs being identified by the presence of li absorption at 6708 in their spectra .
kelu-1 was one of the first such brown dwarfs discovered ..
Please generate the next two sentences of the article | it was found at a trigonometric distance of 18.7 pc @xcite as part of a proper motion survey @xcite . since kelu-1 s discovery , more than 400 l dwarfs have been classified in large surveys such as the deep near - infrared survey ( denis ) , the 2-micron all - sky survey ( 2mass ) , and the sloan digital sky survey ( sdss ) .
a spectral class sequence was established @xcite , and kelu-1 was subsequently assigned a spectral type of l2 in the optical @xcite and l3 in the near - ir @xcite . |
6,148 | Suppose that you have an abstract for a scientific paper: the propagation of electrostatic waves in an unmagnetized collisionless pair - ion plasma with immobile positively charged dusts is studied for both large- and small - amplitude perturbations . using a two - fluid model for pair - ions
, it is shown that there appear two linear ion modes , namely the
fast " and slow " waves in dusty pair - ion plasmas .
the properties of these wave modes are studied with different mass @xmath0 and temperature @xmath1 ratios of negative to positive ions , as well as the effects of immobile charged dusts @xmath2 . for large - amplitude waves ,
the pseudopotential approach is performed , whereas the standard reductive perturbation technique ( rpt ) is used to study the small - amplitude korteweg - de vries ( kdv ) solitons .
the profiles of the pseudopotential , the large amplitude solitons as well as the dynamical evolution of kdv solitons are numerically studied with the system parameters as above .
it is found that the pair - ion plasmas with positively charged dusts support the propagation of solitary waves ( sws ) with only the negative potential .
the results may be useful for the excitation of sws in laboratory dusty pair - ion plasmas , electron - free industrial plasmas as well as for observation in space plasmas where electron density is negligibly small compared to that of negative ions . .
And you have already written the first three sentences of the full article: a typical plasma consisting of electrons and positive ions essentially causes temporal as well as spatial variations of collective phenomena due to large - mass difference between these particles .
this asymmetric diversity of collective plasma phenomena can , however , be nullified in pair - ion plasmas consisting of positive and negative ions with equal mass . in the latter , the space - time parity can be maintained because of the same mobility of the particles under electromagnetic forces .
such pair - ion plasmas have been generated in the laboratory , and three kinds of electrostatic modes have been experimentally observed to propagate along magnetic - field lines in paired fullerene - ion plasmas @xcite ..
Please generate the next two sentences of the article | furthermore , in many industries such as integrated - circuit fabrication , there requires a plasma source having no energetic electrons in the plasma , since the deposited film is strongly damaged by a high - energy electron .
for this purpose , a radio - frequency plasma source has also been developed @xcite . |
6,149 | Suppose that you have an abstract for a scientific paper: the amount , timing and ultimate location of mass transfer and induced star formation in galaxy collisions are sensitive functions of orbital and galaxy structural parameters .
i discuss the role of detailed case studies and describe the results for two systems , arp 284 and ngc 2207/ic 2163 , that have been studied with both multiwaveband observations , and detailed dynamical models .
the models yield the mass transfer and compressional histories of the encounters and the `` probable causes '' or triggers of individual star - forming regions .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: there are two general approaches to the study of the complex effects of galaxy collisions .
the first is statistical , such as the study of particular properties of a reasonable sample of interacting galaxy systems , or a grid of numerical models covering some range of initial conditions .
the second approach is the case study , the detailed investigation of a particular collisional system ..
Please generate the next two sentences of the article | the first approach is the path more frequently followed , in the literature .
a great deal can be learned from observations of the global properties of many systems , which are easier to acquire ( individually ) , than the high sensitivity , high resolution , multi - wavelength data needed for a good case study . in the realm of simulations , the statistical approach also has many attractions . |
6,150 | Suppose that you have an abstract for a scientific paper: in this paper , i present results from a theoretical and numerical ( monte carlo ) _
n - particle _ fully relativistic four - dimensional analysis of penrose scattering processes ( compton and @xmath0 ) in the ergosphere of a supermassive kerr ( rotating ) black hole .
these general relativistic model calculations surprisingly reveal that the observed high energies and luminosities of quasars and other active galactic nuclei , the collimated jets about the polar axis , and the asymmetrical jets ( which can be enhanced by relativistic doppler beaming effects ) _ all _ are inherent properties of rotating black holes . from this analysis
, it is shown that the penrose scattered escaping relativistic particles exhibit tightly wound coil - like cone distributions ( highly collimated vortical jet distributions ) about the polar axis , with helical polar angles of escape varying from @xmath1 to @xmath2 for the highest energy particles .
it is also shown that the gravitomagnetic ( gm ) field , which causes the dragging of inertial frames , exerts a force acting on the momentum vectors of the incident and scattered particles , causing the particle emission to be asymmetrical above and below the equatorial plane , thus appearing to break the equatorial reflection symmetry of the kerr metric .
when the accretion disk is assumed to be a two - temperature bistable thin disk / ion corona ( or torus , defining an advection - dominated accretion flow ) , energies as high as @xmath3 gev can be attained by these penrose processes alone ; and when relativistic beaming is included , energies in the tev range can be achieved , agreeing with observations of some bl lac objects . when this model is applied specifically to quasars 3c 279 and 3c 273 , and the seyfert 1 galaxy mcg6 - 30 - 15 , their observed high energy luminosity spectra in general can be explained .
this energy - momentum extraction model can be applied to any size black hole , irrespective of the mass , and therefore applies to microquasars as well....
And you have already written the first three sentences of the full article: for almost four decades , since the discovery of quasars , mounting observational evidence has accumulated that black holes indeed exist in nature .
recent observations ( wilms et al .
2001 ) of the steep emissivity of seyfert 1 galaxy mcg6 - 30 - 15 , indicating strong photon emission at radii near the event horizon ; and observations of the lack of evidence of the expected ion `` dusty '' torus of m87 ( perlman et al ..
Please generate the next two sentences of the article | 2001 ) , have prompted astrophysicists to suggest a new energy source .
however , it is hardly a new energy source to relativists , i.e. , those who study einstein s theory of general relativity . |
6,151 | Suppose that you have an abstract for a scientific paper: we consider a class of probability measures @xmath0 which have explicit cauchy - stieltjes transforms .
this class includes a symmetric beta distribution , a free poisson law and some beta distributions as special cases .
also , we identify @xmath1 as a free compound poisson law with lvy measure a monotone @xmath2-stable law .
this implies the free infinite divisibility of @xmath3 .
moreover , when symmetric or positive , @xmath1 has a representation as the free multiplication of a free poisson law and a monotone @xmath2-stable law .
we also investigate the free infinite divisibility of @xmath0 for @xmath4 .
special cases include the beta distributions @xmath5 which are freely infinitely divisible if and only if @xmath6 .
mathematics subject classification 2010 : 46l54 ; 46l53 key words : free infinite divisibility , free poisson law , monotone stable law , beta distribution .
And you have already written the first three sentences of the full article: in random matrix theory , a marchenko - pastur law describes the asymptotic behavior of the spectrum of the so - called wishart matrices @xcite . in free probability , a marchenko - pastur ( or free poisson ) law plays the role that a poisson distribution does in probability theory : it is the limiting distribution of @xmath7 when @xmath8 . for this reason
it is called a free poisson law in the context of free probability . on the other hand
, an arcsine law appears in probability theory as the law of the proportion of the time during which a wiener process is non - negative . in monotone probability.
Please generate the next two sentences of the article | , an arcsine law plays the role of a gaussian law @xcite .
in particular , an arcsine law is a monotone stable law with stability index @xmath9 @xcite . |
6,152 | Suppose that you have an abstract for a scientific paper: in this article , i summarise peter hall s contributions to high - dimensional data , including their geometric representations and variable selection methods based on ranking .
i also discuss his work on classification problems , concluding with some personal reflections on my own interactions with him . .
And you have already written the first three sentences of the full article: peter hall wrote many influential works on high - dimensional data , though notably he largely eschewed the notions of sparsity and penalised likelihood that have become so popular in recent years .
nevertheless , he was interested in variable selection , and wrote several papers that involved ranking variables in some way . perhaps his most well - known papers in this area , though , concern geometrical representations of high - dimensional data .
@xcite was one of the pioneering works in the early days of high - dimensional data analysis that tried to understand the properties of low - dimensional projections of a high - dimensional isotropic random vector @xmath0 in @xmath1 ..
Please generate the next two sentences of the article | as motivation , let @xmath2 have @xmath3 and suppose that @xmath4 this condition says that the regression function of @xmath5 on @xmath6 is linear . then , using the isotropy of @xmath0 , @xmath7 moreover , @xmath8 and we conclude that @xmath9 , or equivalently , @xmath10 the left - hand side of is always non - negative , so can be used as a measure of the extent to which the condition holds .
remarkably , under very mild conditions on the distribution of @xmath0 , @xcite proved that if @xmath11 is drawn from the uniform distribution on the unit euclidean sphere in @xmath1 , then @xmath12 as @xmath13 . |
6,153 | Suppose that you have an abstract for a scientific paper: the game of memory is played with a deck of @xmath0 pairs of cards .
the cards in each pair are identical . the deck is shuffled and the cards laid face down . a move consists of flipping over first one card then another .
the cards are removed from play if they match . otherwise , they are flipped back over and the next move commences .
a game ends when all pairs have been matched .
we determine that , when the game is played optimally , as @xmath1 : * the expected number of moves is @xmath2 .
* the expected number of times two matching cards are unwittingly flipped over is @xmath3 . *
the expected number of flips until two matching cards have been seen is @xmath4 . .
And you have already written the first three sentences of the full article: any respectable list of desert island card games must include war to pass the time ( the expected length of a game is infinite , after all @xcite ) .
but to maintain your remembrance of things past , it s hard to beat the game of memory .
memory is played with a deck of @xmath5 cards ..
Please generate the next two sentences of the article | the cards are numbered from @xmath6 up to @xmath0 , with each number appearing twice . the deck is shuffled and then the cards are laid face down in a tableau .
a _ move _ consists of flipping first one card and then a second . |
6,154 | Suppose that you have an abstract for a scientific paper: if @xmath0 is frobenius split , then so is its normalization and we explore conditions which imply the converse . to do this , we recall that given an @xmath1-linear map @xmath2 , it always extends to a map @xmath3 on the normalization of @xmath0 . in this paper
, we study when the surjectivity of @xmath3 implies the surjectivity of @xmath4 . while this does nt occur generally , we show it always happens if certain tameness conditions are satisfied for the normalization map .
our result has geometric consequences including a connection between @xmath5-pure singularities and semi - log canonical singularities , and a more familiar version of the ( @xmath5-)inversion of adjunction formula .
frobenius map , frobenius splitting , f - purity , semi - log canonical , log canonical , inversion of adjunction , normalization , seminormal .
And you have already written the first three sentences of the full article: frobenius splittings of algebraic varieties appear prominently in tight closure theory , have emerged as a fundamental tool in the study of the representation theory of algebraic groups , and have tantalizing links to concepts in the minimal model program .
suppose that @xmath6 is a reduced ring of characteristic @xmath7 with normalization in its total ring of fractions @xmath8 .
it follows from ( * ? ? ?.
Please generate the next two sentences of the article | * exercise 1.2.4(e ) ) that if @xmath9 is frobenius split then so is @xmath10 .
the goal of this paper is to study to what extent the converse holds . |
6,155 | Suppose that you have an abstract for a scientific paper: pairwise comparison matrices are widely used in multicriteria decision making .
this article applies incomplete pairwise comparison matrices in the area of sport tournaments , namely proposing alternative rankings for the 2010 chess olympiad open tournament .
it is shown that results are robust regarding scaling technique . in order to compare different rankings ,
a distance function is introduced with the aim of taking into account the subjective nature of human perception .
analysis of the weight vectors implies that methods based on pairwise comparisons have common roots .
visualization of the results is provided by multidimensional scaling on the basis of the defined distance .
the proposed rankings give in some cases intuitively better outcome than currently used lexicographical orders . .
And you have already written the first three sentences of the full article: there are some sport tournaments where the ranking of the competitors is based on the results of games played against each other . in the world of sport
there is no consensus in using a particular ranking method .
various evaluation methods have been applied to different events taking into account the specifics of the particular sport activity ..
Please generate the next two sentences of the article | further complication emerges when participants are teams , and the final ranking should also reflect individual results .
one characteristic example for that situation is a chess team championship . in this article |
6,156 | Suppose that you have an abstract for a scientific paper: dendrites with developed sidebranches are numerically studied with a coupled map lattice model .
the competitive dynamics among sidebranches determines the shape of the envelope .
the envelope has a parabolic shape near the tip of the dendrite and the envelope angle with respect to the main branch increases up to 45@xmath0 finally . in an intermediate region ,
the envelope grows roughly in a power law , however , the exponent increases gradually as a function of the distance from the tip .
the competitive dynamics among many branches is also observed in a unidirectional growth from a linear seed , and it is compared with the competitive dynamics of sidebranches . .
And you have already written the first three sentences of the full article: pattern formations in diffusion fields have been studied as a typical nonlinear and nonequilibrium problem.@xcite the dendrite is a typical pattern observed in crystal growth . the tip velocity and the shape near the tip region
have been intensively studied .
the growth law of the dendrite is expressed as @xmath1 , where @xmath2 is the tip velocity and @xmath3 is the radius of curvature of the parabolic tip.@xcite the parabolic structure of the dendritic tip is linearly stable and the formation of sidebranches is considered to be due to some noise effects.@xcite perturbations are expected to grow as @xmath4 , where @xmath5 is the distance from the dendritic tip,@xcite and they grow into sidebranches ..
Please generate the next two sentences of the article | well - developed sidebranches can be easily observed in experiments of succinonitrile and nh@xmath6cl .
there are some quantitative investigations about the well - developed sidebranches . |
6,157 | Suppose that you have an abstract for a scientific paper: the neutrino telescope is being constructed in the mediterranean sea .
it consists of a large three - dimensional array of photo - multiplier tubes .
the data acquisition system of the detector takes care of the digitisation of the photo - multiplier tube signals , data transport , data filtering , and data storage .
the detector is operated using a control program interfaced with all elements .
the design and the implementation of the data acquisition system are described . , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , neutrino telescope , data acquisition system .
And you have already written the first three sentences of the full article: the neutrino telescope @xcite is used to study astrophysical sources by detecting the high - energy neutrinos that these sources may emit .
the detector is deployed on the seabed at a depth of 2.5 km , and consists of a large three - dimensional array of 900 light - sensitive photo - multiplier tubes ( pmts @xcite , @xcite ) .
neutrinos are detected indirectly , after an interaction inside or in the vicinity of the detector ..
Please generate the next two sentences of the article | the produced charged particles emit cherenkov light , which can be detected by the pmts . from the known positions of the pmts , and the measured arrival times of the cherenkov photons
, the signal produced by these charged particles can be distinguished from the background . |
6,158 | Suppose that you have an abstract for a scientific paper: this paper introduces a space - continuous force - based model for simulating pedestrian dynamics .
the main interest of this work is the quantitative description of pedestrian movement through a bottleneck .
measurements of flow and density will be presented and compared with empirical data .
the results of the proposed model show a good agreement with empirical data .
furthermore , we emphasize the importance of volume exclusion in force - based models . .
And you have already written the first three sentences of the full article: recently pedestrian dynamics has been gaining increasing interest .
one focus of this research area is the security of people , e.g. , trying to optimize evacuation processes by minimizing evacuation time . to achieve this `` benchmark '' architects and civil engineers need to have an idea about the minimal necessary width of exit doors , their optimal placement , length of escape routes , etc .
usually legal regulations and other descriptive specifications in handbooks provide requirements , which are in general not flexible enough for complex buildings ..
Please generate the next two sentences of the article | however , simulations of pedestrian dynamics offer the possibility to analyze and understand the dynamics of pedestrian streams in the building to be designed .
this is useful to ease decisions e.g. , dimensioning of emergency doors , and make them more realistic and adapted to different architectures . in this work , |
6,159 | Suppose that you have an abstract for a scientific paper: we investigate a large angle photodisintegration of two nucleons from the @xmath0he nucleus within the framework of the hard rescattering model ( hrm ) . in the hrm a quark of one nucleon knocked out by an incoming photon rescatters with a quark of the other nucleon leading to the production of two nucleons with large relative momentum . assuming the dominance of the quark - interchange mechanism in a hard nucleon - nucleon scattering , the hrm allows the expression of the amplitude of a two - nucleon break - up reaction through the convolution of photon - quark scattering , @xmath1 hard scattering amplitude and nuclear spectral function which can be calculated using a nonrelativistic @xmath0he wave function .
the photon - quark scattering amplitude can be explicitly calculated in the high energy regime , whereas for @xmath1 scattering one uses the fit of the available experimental data .
the hrm predicts several specific features for the hard breakup reaction .
first , the cross section will approximately scale as @xmath2 .
secondly , the @xmath3 weighted cross section will have the shape of energy dependence similar to that of @xmath4 weighted @xmath1 elastic scattering cross section .
also one predicts an enhancement of the @xmath5 breakup relative to the @xmath6 breakup cross section as compared to the results from low energy kinematics .
another result is the prediction of different spectator momentum dependencies of @xmath5 and @xmath6 breakup cross sections .
this is due to the fact that same - helicity @xmath5-component is strongly suppressed in the ground state wave function of @xmath0he . because of this suppression the hrm predicts significantly different asymmetries for the cross section of polarization transfer @xmath1 breakup reactions for circularly polarized photons . for the @xmath5 breakup
this asymmetry is predicted to be zero while for the @xmath6 it is close to @xmath7 . .
And you have already written the first three sentences of the full article: two - body breakup processes involving nuclei at high momentum and energy transfer play an important role in studies of nuclear qcd .
the uniqueness of these processes is in the effectiveness by which large values of invariant energy are produced at rather moderate values of beam energy .
the kinematics of two - body photodisintegration provide the relation @xmath8 in which the produced invariant energy grows with the energy of the probe twice as fast as compared , for example , to hard processes involving two protons , in which case @xmath9 . as it follows from eq.([s ] ) , already at photon energies of @xmath10 gev the produced invariant mass on one nucleon , @xmath11 , exceeds the threshold at which deep - inelastic processes become important , @xmath12 gev . combining the above property with a requirement that the momentum transfer in the reaction exceeds the masses of the particles.
Please generate the next two sentences of the article | involved in the scattering ( @xmath13 ) one sets into a hard scattering kinematic regime , in which case we expect that only the minimal fock components dominate in the wave function of the particles involved in the scattering .
assuming that all the constituents of minimal fock component participate in a hard scattering one arrives at the constituent - counting rule@xcite . |
6,160 | Suppose that you have an abstract for a scientific paper: spin-@xmath0 bilayer heisenberg models ( nearest - neighbor square lattice antiferromagnets in each layer , with antiferromagnetic interlayer couplings ) are treated using dimer mean - field theory for general @xmath0 and high - order expansions about the dimer limit for @xmath1 .
we suggest that the transition between the dimer phase at weak intraplane coupling and the nel phase at strong intraplane coupling is continuous for all @xmath0 , contrary to a recent suggestion based on schwinger boson mean - field theory .
we also present results for @xmath2 layers based on expansions about the ising limit : in every respect the @xmath2 bilayers appear to behave like @xmath3 bilayers , further supporting our picture for the nature of the order - disorder phase transition . .
And you have already written the first three sentences of the full article: the bilayer heisenberg antiferromagnet , @xmath4 where the intralayer couplings run over nearest neighbors on square lattices and the @xmath5 are @xmath3 quantum spins , has turned out to be an excellent testing ground for notions of quantum criticality .
a variety of controlled calculations , such as strong - coupling expansions at zero temperature ( starting with the work of hida@xcite and extended by two of the present authors@xcite ) , finite - temperature quantum monte carlo calculations@xcite and high - temperature expansions@xcite fit extremely well into the general field - theoretic framework for zero - temperature order - disorder critical points in unfrustrated two - dimensional quantum antiferromagnets.@xcite the critical point in the @xmath3 bilayer heisenberg model is between a nel ordered phase when @xmath6 is sufficiently large ( greater than the critical value @xmath7 ) and a magnetically disordered `` dimer '' phase which is the adiabatic continuation of the @xmath8 ground state ( which is a product of interlayer singlet pair wavefunctions ) .
the universality class of the phase transition is the same as for finite - temperature transitions in @xmath9 , @xmath10 symmetric models ..
Please generate the next two sentences of the article | it seemed most natural to us that for larger values of the quantum spin @xmath0 the same scenario would play out : the value of @xmath11 would change , but qualitatively nothing would be different .
it therefore came as a surprise when ng , zhang , and ma@xcite described the results of schwinger boson mean - field ( sbmf ) calculations , which indicate that for @xmath12 the transition between magnetically ordered and disordered phases is _ first - order_. the calculation leads to @xmath13 , and hence indicates that for all physical values of @xmath0 the transition should be first - order ; but it is reasonable to accept the suggestion of ng _ et al . _ |
6,161 | Suppose that you have an abstract for a scientific paper: in a double slit interference experiment , the wave function at the screen with both slits open is not exactly equal to the sum of the wave functions with the slits individually open one at a time .
the three scenarios represent three different boundary conditions and as such , the superposition principle should not be applicable
. however , most well known text books in quantum mechanics implicitly and/or explicitly use this assumption which is only approximately true . in our present study , we have used the feynman path integral formalism to quantify contributions from non - classical paths in quantum interference experiments which provide a measurable deviation from a naive application of the superposition principle .
a direct experimental demonstration for the existence of these non - classical paths is hard .
we find that contributions from such paths can be significant and we propose simple three - slit interference experiments to directly confirm their existence .
quantum mechanics has been one of the most successful theories of the twentieth century , both in describing fundamental aspects of modern science as well as in pivotal applications .
however , inspite of these obvious triumphs , there is universal agreement that there are aspects of the theory which are counter - intuitive and perhaps even paradoxical .
furthermore , understanding fundamental problems involving dark matter and dark energy @xcite in cosmology may need a consistent quantum theory of gravity .
unification of quantum mechanics and general relativity towards a unified theory of quantum gravity @xcite is the holy grail of modern theoretical physics .
such unification attempts involve modifications of either or both theories .
however , all such attempts would rely very strongly on precise knowledge and understanding of the current versions of both theories .
this makes precision tests of fundamental aspects of both quantum mechanics and general relativity very important to provide guiding beacons for....
And you have already written the first three sentences of the full article: we thank aveek bid , dwarkanath k.s .
, subroto mukerjee , robert myers , rajaram nityananda , barry sanders , rafael sorkin , radhika vatsan and gregor weihs for useful discussions .
we thank raymond laflamme and anthony leggett for reading through the draft and helpful comments and discussions . as.
Please generate the next two sentences of the article | acknowledges partial support from a ramanujan fellowship , govt . of india .
caldwell , r. & kamionkowski , m. cosmology : dark matter and dark energy . |
6,162 | Suppose that you have an abstract for a scientific paper: the vacuum expectation values of the energy momentum tensor and the fermionic condensate are analyzed for a massive spinor field obeying the mit bag boundary condition on a cylindrical shell in the cosmic string spacetime .
both regions inside and outside the shell are considered . by applying to the corresponding mode - sums a variant of the generalized abel
plana formula , we explicitly extract the parts in the expectation values corresponding to the cosmic string geometry without boundaries . in this way
the renormalization procedure is reduced to that for the boundary - free cosmic string spacetime .
the parts induced by the cylindrical shell are presented in terms of integrals rapidly convergent for points away from the boundary .
the behavior of the vacuum densities is investigated in various asymptotic regions of the parameters . in the limit of large values of the planar angle deficit ,
the boundary - induced expectation values are exponentially suppressed . as a special case
, we discuss the fermionic vacuum densities for the cylindrical shell on the background of the minkowski spacetime .
pacs numbers : 03.70.+k , 98.80.cq , 11.27.+d .
And you have already written the first three sentences of the full article: it is well known that different types of topological objects may have been formed in the early universe after planck time by the vacuum phase transition @xcite . depending on the topology of the vacuum manifold these are domain walls , strings , monopoles and textures . among them
the cosmic strings are of special interest . although the recent observational data on the cosmic microwave background radiation have ruled out cosmic strings as the primary source for primordial density perturbations , they are still candidates for the generation of a number of interesting physical effects such as the generation of gravitational waves , gamma ray bursts and high - energy cosmic rays ( see , for instance , @xcite ) . recently , cosmic strings attract a renewed interest partly because a variant of their formation mechanism is proposed in the framework of brane inflation sara02 . in the simplest theoretical model describing the infinite straight cosmic string
the spacetime is locally flat except on the string where it has a delta shaped riemann curvature tensor . in quantum field theory the corresponding non - trivial topology induces non - zero vacuum expectation values for physical observables ..
Please generate the next two sentences of the article | explicit calculations for the geometry of a single cosmic string have been done for different fields @xcite - spin08 .
vacuum polarization effects by higher - dimensional composite topological defects constituted by a cosmic string and global monopole are investigated in refs . |
6,163 | Suppose that you have an abstract for a scientific paper: intracellular positive ions neutralise negative charges on the phosphates of a dna strand conferring greater strength on the hydrogen bonds that connect complementary strands into a double helix and so confer enhanced stability . beyond a certain value of salt concentration
, the dna molecule displays a unstable nature _ in vivo _ as well as _ in vitro_. we consider a wide range of salt concentrations and study the stability of the dna double helix using a statistical model . through numerical calculations we attempt to explain the different behaviour exhibited by dna molecules in this range .
we compare our results with experimental data and find a close agreement . .
And you have already written the first three sentences of the full article: intracellular sodium triggers a cell to progress to cell division @xcite . in many biological activities like creation of daughter cells ,
salt enacts a pivotal role .
it is also a known fact that the two strands of dna carry negative charge due to their phosphate groups ( @xmath0 ) @xcite ..
Please generate the next two sentences of the article | the two strands are connected with each other through the hydrogen bonds between the bases on the opposite strands .
however , the stability of the dna double helix also depends on the charge neutrality of the system . to counter the negative charges on the strands , the cellular environment requires some positive charges in order to nullify the repulsion between negative charges . |
6,164 | Suppose that you have an abstract for a scientific paper: we investigated two - dimensional brittle fragmentation with a flat impact experimentally , focusing on the low impact energy region near the fragmentation - critical point .
we found that the universality class of fragmentation transition disagreed with that of percolation .
however , the weighted mean mass of the fragments could be scaled using the pseudo - control - parameter _
multiplicity_. the data for highly fragmented samples included a cumulative fragment mass distribution that clearly obeyed a power - law .
the exponent of this power - law was @xmath0 and it was independent of sample size .
the fragment mass distributions in this regime seemed to collapse into a unified scaling function using weighted mean fragment mass scaling .
we also examined the behavior of higher order moments of the fragment mass distributions , and obtained multi - scaling exponents that agreed with those of the simple biased cascade model . .
And you have already written the first three sentences of the full article: from asteroids to nuclei , fragmentation phenomena can be seen everywhere .
many scientists and engineers have been fascinated by the fragmentation process , and much effort has been made to understand fragmentation @xcite .
in particular , impact fragmentation of brittle solids has been investigated by simulation and experimentally @xcite ..
Please generate the next two sentences of the article | the results have shown that cumulative fragment mass ( or size ) distributions exhibit a power - law dependence , in which the exponent depends on the dimensionality of the fractured objects .
these results do not depend on the details of fragmentation , such as the material the fractured object is made from or the fragmentation method . |
6,165 | Suppose that you have an abstract for a scientific paper: the associated production of neutral higgs bosons with the @xmath0 gauge boson ( @xmath1 , @xmath2 ) is investigated in the context of the future linear colliders , such as the ilc and clic , within the general two - higgs - doublet model ( 2hdm ) .
we compute the corresponding cross - section for the processes @xmath3 at one - loop , including the full set of corrections at @xmath4 together with the leading @xmath5 terms , in full consistency with the available theoretical and phenomenological constraints .
we find that the wave - function corrections to the external higgs fields are the dominant source of the quantum effects , which turn out to be large and negative ( e.g. @xmath6 ) in all the @xmath7 range , and located predominantly in the region around @xmath8 and moderate values of the parameter @xmath9 ( being @xmath10 ) .
this behavior can be ultimately traced back to the enhancement potential of the triple higgs boson self - couplings , a trademark feature of the 2hdm with no counterpart in the higgs sector of the minimal supersymmetric standard model . even under this substantial depletion of the one - loop corrected signal ( which is also highly distinctive with respect to the sm expectation for @xmath11 ) ,
the predicted higgs - strahlung rates comfortably reach a few tens of femtobarn , which means barely @xmath12 events per @xmath13 @xmath14 of integrated luminosity . due to their great complementarity , we argue that the combined analysis of the higgs - strahlung events ( @xmath1 , @xmath2 ) and the previously computed one - loop higgs - pair production processes ( @xmath15 , @xmath16 ) could be instrumental to probe the structure of the higgs sector at future linac facilities . .
And you have already written the first three sentences of the full article: after more than 40 years since the seminal ideas coined by a handful of theoretical pioneers@xcite , our present understanding of the electroweak symmetry breaking ( ewsb ) phenomenon through the higgs ( englert - brout and guralnik - hagen - kibble ) mechanism is still rather incomplete and experimentally inconclusive . on the one hand
, there is no compelling alternative to consistently embed the ewsb mechanism into the quantum field theoretical description of particle physics offered by the in so many regards successful standard model ( sm ) of the strong and electroweak interactions . on the other hand
, we do not have a single phenomenological hint of the existence of elementary scalar fields , not to mention the fact that we do not understand how to make compatible the ewsb mechanism and its associated vacuum energy with fundamental problems of different scope , for example in the domain of cosmology ..
Please generate the next two sentences of the article | still , the possibility to describe the inner theoretical structure of the sm through the ewsb mechanism is so successful within the restricted particle physics domain that it would not be wise , not even advisable , to cease our pursue of the phenomenological implications of the higgs mechanism paradigm till the limits of the current experimental possibilities .
it goes without saying that the quest for experimental evidences of the higgs boson is a most preeminent milestone of the upcoming generation of collider facilities . |
6,166 | Suppose that you have an abstract for a scientific paper: compressing a porous , fluid - filled material will drive the interstitial fluid out of the pore space , as when squeezing water out of a kitchen sponge .
inversely , injecting fluid into a porous material can deform the solid structure , as when fracturing a shale for natural gas recovery .
these poromechanical interactions play an important role in geological and biological systems across a wide range of scales , from the propagation of magma through the earth s mantle to the transport of fluid through living cells and tissues .
the theory of poroelasticity has been largely successful in modeling poromechanical behavior in relatively simple systems , but this continuum theory is fundamentally limited by our understanding of the pore - scale interactions between the fluid and the solid , and these problems are notoriously difficult to study in a laboratory setting . here , we present a high - resolution measurement of injection - driven poromechanical deformation in a system with granular microsctructure : we inject fluid into a dense , confined monolayer of soft particles and use particle tracking to reveal the dynamics of the multi - scale deformation field .
we find that a continuum model based on poroelasticity theory captures certain macroscopic features of the deformation , but the particle - scale deformation field exhibits dramatic departures from smooth , continuum behavior .
we observe particle - scale rearrangement and hysteresis , as well as petal - like mesoscale structures that are connected to material failure through spiral shear banding . .
And you have already written the first three sentences of the full article: poromechanics couples the mechanical deformation of a porous solid with fluid flow through its internal structure @xcite . in biophysics ,
poromechanics plays an important role in the growth and deformation of cells and tissues ( _ e.g. _ , @xcite ) , and it is the dominant mechanism underlying plant motion ( _ e.g. _ , @xcite ) . in both pure and applied geophysics , poromechanics has been studied intensely in the context of subsurface pressurization during fluid injection , such as in geothermal energy extraction or carbon dioxide sequestration ( _ e.g. _ , @xcite ) , and particularly in the context of hydraulic fracture for enhanced oil or gas recovery ( _ e.g. _ , @xcite ) .
poromechanical deformations are poro__elastic _ _ when they are controlled by the reversible storage and release of elastic energy ..
Please generate the next two sentences of the article | the classical theory of poroelasticity couples linear elasticity with darcy s law for fluid flow through a porous medium , and the hallmark of these systems is diffusive propagation and dissipation of fluid pressure with characteristic time scale @xmath0 , where @xmath1 is the viscosity of the fluid , @xmath2 is a characteristic length scale , and @xmath3 and @xmath4 are the elastic modulus and permeability of the solid skeleton .
this approach is valid for small deformations , but many real systems feature large deformations , small - scale microstructure , or physical mechanisms such as damage , growth , or swelling , that lead to a strongly nonlinear coupling between the pore structure and the fluid flow @xcite . |
6,167 | Suppose that you have an abstract for a scientific paper: the superconducting proximity effect leads to strong modifications of the local density of states in diffusive or chaotic cavity josephson junctions , which displays a phase - dependent energy gap around the fermi energy .
the so - called minigap of the order of the thouless energy @xmath0 is related to the inverse dwell time in the diffusive region in the limit @xmath1 , where @xmath2 is the superconducting energy gap . in the opposite limit of a large thouless energy @xmath3 ,
a small new feature has recently attracted attention , namely , the appearance of a further secondary gap , which is around two orders of magnitude smaller compared to the usual superconducting gap .
it appears in a chaotic cavity just below the superconducting gap edge @xmath2 and vanishes for some value of the phase difference between the superconductors .
we extend previous theory restricted to a normal cavity connected to two superconductors through ballistic contacts to a wider range of contact types .
we show that the existence of the secondary gap is not limited to ballistic contacts , but is a more general property of such systems .
furthermore , we derive a criterion which directly relates the existence of a secondary gap to the presence of small transmission eigenvalues of the contacts . for generic continuous distributions of transmission eigenvalues of the contacts ,
no secondary gap exists , although we observe a singular behavior of the density of states at @xmath2 .
finally , we provide a simple one - dimensional scattering model which is able to explain the characteristic `` smile '' shape of the secondary gap . .
And you have already written the first three sentences of the full article: one of the most striking impacts of a contact with a superconductor ( s ) onto a small piece of normal metal ( n ) is the modification of the local density of states ( ldos ) .
this effect , known as the superconducting proximity effect , is related to the induction of superconducting correlations resulting in a finite value of the pair amplitude @xmath4 on the normal side @xcite . in the absence of phonon
mediated attraction between electrons on the normal side , decoherence between electronlike and holelike amplitudes leads to an exponential decay of the pair amplitude with distance from the contact , with a characteristic length scale exceeding the superconducting coherence length ..
Please generate the next two sentences of the article | modification of the ldos on both sides of the contact strongly depends on the scattering properties of the contacts ( described in terms of transmission eigenvalues ) and the properties of the normal region ( geometry , size , and impurity concentration ) . in the case of diffusive systems , it was predicted theoretically that the ldos can even be fully suppressed in a specific energy range around the fermi energy which is known as the minigap @xcite .
the minigap width is of the order of the inverse dwell time in the normal structure , which is given by the thouless energy @xmath5 , where @xmath6 denotes the mean level spacing of the normal region and @xmath7 is the total conductance of the structure which is assumed large compared to the conductance quantum @xmath8 . in the decades after its discovery |
6,168 | Suppose that you have an abstract for a scientific paper: it is shown that the nonequilibrium self - energy of an interacting lattice - fermion model has a unique lehmann representation .
based on the construction of a suitable non - interacting effective medium , we provide an explicit and numerically practicable scheme to construct the lehmann representation for the self - energy , given the lehmann representation of the single - particle nonequilibrium green s function .
this is of particular importance for an efficient numerical solution of dyson s equation in the context of approximations where the self - energy is obtained from a reference system with a small hilbert space .
as compared to conventional techniques to solve dyson s equation on the keldysh contour , the effective - medium approach allows to reach a maximum propagation time which can be several orders of magnitude longer .
this is demonstrated explicitly by choosing the nonequilibrium cluster - perturbation theory as a simple approach to study the long - time dynamics of an inhomogeneous initial state after a quantum quench in the hubbard model on a @xmath0 square lattice .
we demonstrate that the violation of conservation laws is moderate for weak hubbard interaction and that the cluster approach is able to describe prethermalization physics . .
And you have already written the first three sentences of the full article: the study of physical phenomena that arise in strongly correlated systems far from equilibrium has become a field of highly active research recently . @xcite for the theoretical description of such systems , greens - function - based approaches starting from the keldysh formalism @xcite have proven to be very useful . a number of different approximation schemes rely on this concept .
@xcite central to these approaches is the self - energy which is related to the one - particle green s function through dyson s equation .
however , while the numerical solution of dyson s equation is rather straightforward in the equilibrium case , the computational effort is considerably increased for systems out of equilibrium since operations with matrices depending on two independent contour time variables typically scale cubically in the number of time steps ..
Please generate the next two sentences of the article | apart from other challenges characteristic for the respective approach , already this scaling poses a severe limit on the maximal reachable propagation time in a numerical calculation .
applying additional concepts or approximations , such as the generalized kadanoff - baym ansatz@xcite or exploiting a rapid decay of the memory,@xcite are necessary to overcome this limitation . |
6,169 | Suppose that you have an abstract for a scientific paper: super star clusters are one of the most extreme star forming environments in the universe , and the most massive and dense of these may be proto globular clusters . like individual massive stars , the earliest stages of super star cluster evolution are deeply obscured , and therefore our knowledge about their birth environments is currently very incomplete .
however , the study of natal super star clusters has become somewhat of a cottage industry in recent years , and the sample of such objects has been growing rapidly with high - quality long - wavelength data now available from a number of observatories .
the natal super star clusters identified in thermal - infrared and radio observations represent the youngest stage of massive star cluster evolution yet observed .
their properties appear to be similar to those of ultracompact hii regions in the milky way , but scaled up in total mass and luminosity .
i will overview what we think we know about these objects based on existing observations , discuss their relationship to ultracompact hii regions , present new models of their spectral energy distributions based on 3-d simulations , and outline some of the most significant gaps in our current understanding . .
And you have already written the first three sentences of the full article: we know that nearly all massive stars form in clusters ( see , e.g. de wit , these proceedings ) .
therefore , if we wish to understand massive star formation in general , we must understand the clustered mode of star formation .
super star clusters ( sscs ) are the most extreme type of stellar cluster ( and also one of the most extreme star forming environments in the universe ) , with stellar densities exceeding @xmath0 stars pc@xmath1 in their cores . as `` extreme '' objects , one might be tempted to simply think of them as cosmic curiosities ..
Please generate the next two sentences of the article | however , these objects are not only fascinating because of their extreme nature , but also because they hold clues to an important mode of star formation during the time of galaxy assembly .
specifically , most present - day research strongly supports the idea that sscs are the adolescent precursors to the ancient globular clusters that are ubiquitous around massive galaxies in the local universe today . |
6,170 | Suppose that you have an abstract for a scientific paper: we report evidence for a recent burst of star formation located within 9pc of the active nucleus of ngc1097 .
the observational signatures of the starburst include uv absorption lines and continuum emission from young stars observed in a small - aperture _ hst _ spectrum .
the burst is @xmath0 a few @xmath1 10@xmath2yr old , has a mass of @xmath3m@xmath4 , an observed luminosity of 1.5 @xmath1 10@xmath5 l@xmath4 and is obscured by @xmath6 mag .
the importance of this finding is two - fold : ( 1 ) the proximity of the starburst to the active nucleus and thus possible association with it ; ( 2 ) its obscuration by and apparent association with a dusty absorbing medium , while the broad emission lines appear unobscured , suggesting that the starburst could be embedded in a circumnuclear torus as predicted in the unified model of active galactic nuclei . .
And you have already written the first three sentences of the full article: the standard model of an active galactic nucleus ( agn ) consists of a supermassive black hole being fed via an accretion disk .
the model also postulates the presence of a dusty molecular torus surrounding this inner region , and blocking it from view in agns where the line - of - sight intercepts the torus @xcite . for several years
, the only plausible signature of the accretion disk was the `` big blue bump , '' observed in the ultraviolet ( uv ) spectra of active galaxies , which was supposed to be the thermal emission from the disk @xcite ..
Please generate the next two sentences of the article | a more telling feature , such as the kinematic signature of rotating gas , in the form of double - peaked line emission as observed in cataclysmic variables , was only discovered in optical spectra in the 1980s @xcite , and systematic searches were later published by @xcite and by @xcite .
broad , double - peaked emission lines from the nucleus of ngc1097 were reported by @xcite , and similar lines were found in other nearby galaxies with the _ hubble space telescope ( hst ) _ @xcite . |
6,171 | Suppose that you have an abstract for a scientific paper: we outline a non - perturbative procedure for calculating the total photoionization cross - section of two - electron atomic systems .
the procedure is based on the floquet - fourie representation of the solution of the time - dependent schrodinger equation .
the floquet - fourie ansatz produces a set of equations which is recast into a generalized eigenvalue problem by means of the complex rotation procedure . with the use of the hylleraas - type basis functions ,
the total photoionization cross - sections are obtained within the accuracy of a fraction of a percent .
the total photoionization cross - sections for neutral helium are in good agreement with the convergent close - coupling calculations of kheifets and bray [ phys .
rev .
a * 58 * , 4501 ( 1999 ) ] but deviate notably from the experimental data of samson _ et al . _ [ j. phys .
b * 27 * 887 ( 1994 ) ] .
= 8 mm .
And you have already written the first three sentences of the full article: photoionization of two - electron atoms has been studied theoretically by different authors starting from the pioneering paper by @xcite .
review of early literature on this subject can be found in ref .
subsequently , a large number of computations of helium photoionization cross - sections was reported @xcite ..
Please generate the next two sentences of the article | these calculations produced a collection of results varying typically by 5% from each other . on the experimental side , the benchmark set of data was reported by @xcite who measured the total photoionization cross - section of he in the photon energy range from the threshold to 120 ev .
agreement between the theoretical and experimental data was within the same margin of 5% . in the following years , the theoretical interest shifted towards calculation of differential characteristics of the photoionization process and to studies of double photoionization . here , several approaches have been advocated including the many - body perturbation theory @xcite , convergent close - coupling method @xcite , time - dependent close - coupling method @xcite , @xmath0-matrix approach @xcite , and methods based on the computation of the dipole response function @xcite or @xmath1-spline implementations of the exterior complex scaling @xcite . due to this shift of focus |
6,172 | Suppose that you have an abstract for a scientific paper: we have applied the quantal hypernetted - chain equations in combination with the rosenfeld bridge - functional to calculate the atomic and the electronic structure of compressed liquid - rubidium under high pressure ( 0.2 , 2.5 , 3.9 , and 6.1 gpa ) ; the calculated structure factors are in good agreement with experimental results measured by tsuji _
et al .
_ along the melting curve .
we found that the rb - pseudoatom remains under these high pressures almost unchanged with respect to the pseudoatom at room pressure ; thus , the effective ion - ion interaction is practically the same for all pressure - values .
we observe that all structure factors calculated for this pressure - variation coincide almost into a single curve if wavenumbers are scaled in units of the wigner - seitz radius @xmath0 although no corresponding scaling feature is observed in the effective ion - ion interaction .
this scaling property of the structure factors signifies that the compression in liquid - rubidium is uniform with increasing pressure ; in absolute @xmath1-values this means that the first peak - position ( @xmath2 ) of the structure factor increases proportionally to @xmath3 ( @xmath4 being the specific volume per ion ) , as was experimentally observed by tsuji _
et al_. this scaling property comes from a specific feature characteristic for effective ion - ion potential of liquid rubidium : even if the effective liquid - rubidium potential is invariant under this pressure - variation with respect to the potential at room pressure , we can nevertheless observe this scaling property for the structure factors .
this property is obviously characteristic for the potential of alkali metals and we have examined and confirmed this feature for the case of a liquid - lithium potential : starting from the liquid - lithium potential at room pressure we can easily find two sets of densities and temperatures for which the structure factors become practically identical , when scaling @xmath1 in units of @xmath0 . .
And you have already written the first three sentences of the full article: based on density - functional ( df ) theory , we have derived in previous work a set of integral equations , which allows to calculate the ion - ion and the electron - ion correlations in a liquid metal or a plasma , consistent with the bound - electron structure of the ion using only the atomic number @xmath5 as input ; these integral equations are named the quantal hypernetted - chain ( qhnc ) equations,@xcite which are derived from the exact expressions for the ion - ion and electron - ion radial distribution functions ( rdf ) in an electron - ion mixture . up to now , we have applied this approach to liquid metallic hydrogen,@xcite lithium,@xcite sodium,@xcite potassium@xcite and aluminum@xcite obtaining ion - ion structure factors in excellent agreement with experiments . since a liquid metal can be considered as a very special type of a high - density plasma , we can expect from the successful application of the qhnc - method to liquid metals , that this approach is able to provide accurate results for a plasma .
in such a system , both the ionic valency @xmath6 and the electron - ion interaction @xmath7 may vary over a wide range as temperature and density are changed .
our method is in particular suited to treat a plasma , since it is able to calculate the ionization @xmath6 and the electron - ion interaction in a self - consistent manner using the atomic number of the system as the only input data ..
Please generate the next two sentences of the article | recently , we have extended this formalism and have performed a first - principles molecular dynamics ( md ) simulation based on the qhnc theory for alkali metals near the triple point : in this study those small deviations which were still observed between experimental results and qhnc data for the structure factor disappeared completely.@xcite nevertheless , the calculation of the ion - ion rdf in an md simulation is rather time - consuming .
recently , rosenfeld@xcite has proposed a new bridge - functional for hard - spheres ; its construction requires only fundamental measures of the hard - spheres . in combination with the mhnc - approach by replacing the bridge-_function _ by a bridge-_functional _ of the reference system |
6,173 | Suppose that you have an abstract for a scientific paper: we derive a general expression for the multipole expansion of the electro - magnetic interaction in relativistic heavy - ion collisions , which can be employed in higher - order dynamical calculations of coulomb excitation .
the interaction has diagonal as well as off - diagonal multipole components , associated with the intrinsic and relative coordinates of projectile and target .
a simple truncation in the off - diagonal components gives excellent results in first - order perturbation theory for distant collisions and for beam energies up to 200 mev / nucleon .
= 10000 .
And you have already written the first three sentences of the full article: the coulomb excitation of nuclei at relativistic energies is commonly calculated in first - order perturbation theory , using the formalism developed in ref .
the derivation is restricted to distant collision , where the intrinsic radial coordinates are smaller than the minimum distance between the colliding nuclei . in calculations of the coulomb dissociation of proton halo nuclei ,
it is of interest also to consider close collisions , since the density of the valence proton can extend to very large distances ..
Please generate the next two sentences of the article | moreover , higher - order processes may also play a role , as suggested by the non - relativistic calculations of the @xmath0b breakup reported in ref .
@xcite . in order to calculate the coulomb dissociation of halo nuclei at energies where relativistic and higher - order effects can not be ignored |
6,174 | Suppose that you have an abstract for a scientific paper: the @xmath0-rays from the decay of the gdr in the compound nucleus reaction @xmath1o+@xmath2si at bombarding enery of 105 mev have been measured in an experiment using a setup consisting of the combined euroball iv , hector and euclides arrays .
the shape of the rotating compound nucleus , @xmath3ti , is expected to undergo the jacobi transition around spin 28 @xmath4 .
a comparison of the gdr lineshape data with the predictions of the thermal shape fluctuation model , based on the most recent rotating liquid drop lsd calculations , shows evidence for such jacobi shape transition .
in addition to the previously found broad structure in the gdr lineshape region at 1825 mev caused by large deformations , the presence of a low energy component ( around 10 mev ) , due to the coriolis splitting in prolate , well deformed shape has been identified for the first time . .
And you have already written the first three sentences of the full article: the jacobi shape transition , an abrupt change of nuclear shape from an oblate ellipsoid non - collectively rotating around its symmetry axis , to an elongated prolate or triaxial shape , rotating collectively around the shortest axis has been predicted to appear in many nuclei at angular momenta close to the fission limit @xcite .
signatures of the presence of elongated shapes can be found , among others , in the @xmath0-decay of the giant dipole resonance ( gdr ) , in the giant back - bend of the @xmath52 @xmath0-transition energies @xcite and in the angular distribution of the emitted charged particles . until now , however , a firm experimental evidence for the jacobi shape transition in nuclei could not be established .
some indications of such elongated shapes were obtained in the studies of the gdr decay from @xmath6sc@xmath7 @xcite and @xmath3ti@xmath7 @xcite compound nuclei . in the case of @xmath6sc@xmath7 ,.
Please generate the next two sentences of the article | the gdr measurement was inclusive , while for @xmath3ti@xmath7 it was more exclusive , namely it was associated with various @xmath0-multiplicity values .
however , in both studies other explanations , as for example contribution from fission could not be completely ruled out . in order to address in more detail |
6,175 | Suppose that you have an abstract for a scientific paper: we study the whitham equations for the defocusing complex modified kdv ( mkdv ) equation .
these whitham equations are quasilinear hyperbolic equations and they describe the averaged dynamics of the rapid oscillations which appear in the solution of the mkdv equation when the dispersive parameter is small . the oscillations are referred to as dispersive shocks .
the whitham equations for the mkdv equation are neither strictly hyperbolic nor genuinely nonlinear .
we are interested in the solutions of the whitham equations when the initial values are given by a step function .
we also compare the results with those of the defocusing nonlinear schrdinger ( nls ) equation . for the nls equation ,
the whitham equations are strictly hyperbolic and genuinely nonlinear .
we show that the weak hyperbolicity of the mkdv - whitham equations is responsible for an additional structure in the dispersive shocks which has not been found in the nls case .
whitham equations , non - strictly hyperbolic equations , dispersive shocks * ams subject classifications .
* 35l65 , 35l67 , 35q05 , 35q15 , 35q53 , 35q58 .
And you have already written the first three sentences of the full article: in @xcite , pierce and tian studied the self - similar solutions of the whitham equations which describe the zero dispersion limits of the kdv hierarchy . the main feature of the whitham equations for the higher members of the hierarchy , of which the kdv equation is the first member , is that these whitham equations are neither strictly hyperbolic nor genuinely nonlinear .
this is in sharp contrast to the case of the kdv equation whose whitham equations are strictly hyperbolic and genuinely nonlinear [ lax2 ] . in this paper , we extend their studies to the case of the complex modified kdv equation , which is the second member of the defocusing nonlinear schrdinger hierarchy .
the whitham equations for the defocusing nls equation are strictly hyperbolic and genuinely nonlinear , and they have been studied extensively ( see for examples , @xcite ) . however , for the mkdv equation , the whitham equations are neither strictly hyperbolic nor genuinely nonlinear ..
Please generate the next two sentences of the article | let us begin with a brief description of the zero dispersion limit of the solution of the nls equation @xmath0 with the initial data @xmath1 here @xmath2 and @xmath3 are real functions that are independent of @xmath4 .
writing the solution @xmath5 , and using the notation @xmath6 , @xmath7 , one obtains the conservation form of the defocusing nls equation @xmath8 the mass density @xmath9 and momentum density @xmath10 have weak limits as @xmath11 @xcite . |
6,176 | Suppose that you have an abstract for a scientific paper: the effect on parametric instability growth of pump wave incoherence is treated by deriving a set of equations governing the space - time evolution of the ensemble - average coupled - mode amplitudes and intensities .
particular attention is paid to establishing the regions of validity of the statistical description .
thresholds , growth rates , and amplification rates are given for both spatially and temporally incoherent pump waves . both absolutely and convectively unstable modes are considered .
the statistical results are verified where appropriate by numerical integration of the coupled - mode equations with different models of pump incoherence . .
And you have already written the first three sentences of the full article: the requirements of laser fusion targets for high power lasers with good laser beam uniformity has driven a quest for new techniques for smoothing the intensity variations on the target surface .
early attempts at beam smoothing[1 ] were not well characterized but more systematic techniques[2 - 6 ] have demonstrated significant improvements in beam uniformity .
all techniques involve introduction of phase nonuniformities which replace the normal beam pattern , typically containing substantial hotspots , with a smaller - length - scale speckle pattern ..
Please generate the next two sentences of the article | further addition of bandwidth to the laser provides temporal smoothing of the speckle .
the primary motivation for investing in these smoothing schemes is to reduce the initial nonuniformities that can seed fluid instabilities such as rayleigh - taylor , yet there is also palpable interest in reducing the strength of laser plasma instabilities such as stimulated raman or brillouin scattering or two plasmon decay . supplying a theoretical framework for understanding these laser plasma interactions with smoothed laser beams is the task we undertake in this article . in a subsequent article[7 ] , the results obtained here will be applied to particular instabilities in geometries of interest . with the usual assumptions about slow variation of parameters with respect to the frequencies @xmath0 and wave vectors k@xmath1 of the wave |
6,177 | Suppose that you have an abstract for a scientific paper: we present exploratory results for the hadron mass spectrum and pseudoscalar meson decay constants using mixed actions .
we use improved staggered sea quarks and hyp - smeared overlap valence quarks .
we obtain good signals on 10 configurations at one lattice spacing and two different sets of sea quark masses . .
And you have already written the first three sentences of the full article: solving lattice qcd to high precision requires the use of dynamical ginsparg - wilson light quarks .
however , this is computationally expensive . therefore , as a starting place , we take improved staggered quark configurations , which have the advantage of light sea quarks , and use an overlap valence quark action , which has the correct chiral and flavour symmetries .
this has its own disadvantages ..
Please generate the next two sentences of the article | firstly , the overlap inversion is still relatively expensive and , secondly , because we have different actions for the sea and valence quarks , it is not straightforward to interpret the results .
mixed actions are inevitable in the improved staggered programme , because we do not yet have a local version of the sea quark action to use for the valence quarks . also , it is complicated to measure some quantities in the improved staggered formalism . |
6,178 | Suppose that you have an abstract for a scientific paper: the inclusive distributions of gluons and pions for high - energy nn collisions are calculated .
the results for several unintegrated gluon distributions ( ugd s ) from the literature are compared .
we find huge differences in both rapidity and @xmath0 of gluons and @xmath1 s in nn collisions for different models of ugd s .
the karzeev - levin ugd gives good description of momentum distribution of charged hadrons at midrapidities .
we find that the gluonic mechanism discussed does not describe the inclusive spectra of charged particles in the fragmentation region . .
And you have already written the first three sentences of the full article: the recent results from rhic ( see e.g. @xcite ) have attracted renewed interest in better understanding the dynamics of particle production , not only in nuclear collisions .
quite different approaches have been used to describe the particle spectra from the nuclear collisions @xcite . the model in ref.@xcite with an educated guess for ugd describes surprisingly well the whole charged particle rapidity distribution by means of gluonic mechanisms only .
such a gluonic mechanism would lead to the identical production of positively and negatively charged hadrons ..
Please generate the next two sentences of the article | the recent results of the brahms experiment @xcite put into question the successful description of ref.@xcite . in the light of this experiment , it becomes obvious that the large rapidity regions have more complicated flavour structure .
i discuss the relation between ugd s in hadrons and the inclusive momentum distribution of particles produced in hadronic collisions . |
6,179 | Suppose that you have an abstract for a scientific paper: we implement the squeezing operation as a genuine quantum gate , deterministically and reversibly acting ` online ' upon an input state no longer restricted to the set of gaussian states . more specifically , by applying an efficient and robust squeezing operation for the first time to non - gaussian states
, we demonstrate a two - way conversion between a particle - like single - photon state and a wave - like superposition of coherent states .
our squeezing gate is reliable enough to preserve the negativities of the corresponding wigner functions .
this demonstration represents an important and necessary step towards hybridizing discrete and continuous quantum protocols . from a fundamental point of view
, quantum states of light can behave in a complementary fashion , showing both particle - like and wave - like behavior . with regards to an application such as quantum computing , an important proposal for universally processing photonic qubits
@xcite makes use of quantum particle detections ( i.e. , photon counting ) and quantum wave evolutions ( i.e. , quantum interferences through passive , energy - preserving linear optical circuits ) . in this scheme , however , the required ancilla states consist of many highly entangled photons and thus are out of reach of current experimental capabilities .
it is therefore reasonable to extend the toolbox of optical quantum operations in order to reduce the cost of the necessary quantum resources .
for instance , apart from discrete ` click by click ' measurements that rely on the particle - like nature of light @xcite , quantum light fields may be detected more naturally via continuous phase - space measurements exploiting their wave - like features @xcite .
in fact , two recent continuous - variable teleportation experiments on non - gaussian input states , using gaussian entanglement and gaussian homodyne measurements , demonstrate that not only a wave - like coherent - state superposition ( css ) @xcite , but also a particle - like photonic....
And you have already written the first three sentences of the full article: when squeezed , the single photon ceases to be a single quantum particle and it becomes a superposition in an infinite - dimensional hilbert space . as such , it gains many useful abilities exploited in the various quantum protocols @xcite , but its description and , consequently , analysis becomes more involved .
however , we can greatly benefit from the well - known similarity between squeezed single photons and superposed coherent states @xcite .
if we are able to rigorously confirm that a single photon was transformed into a high - quality css and that a css was transformed back into a high - quality single photon , we can safely claim that the squeezing operation works as intended and that it should have its potential place in future applications . in order to quantitatively.
Please generate the next two sentences of the article | assess the transition between the single photon and the css , we employ the following figures of merit .
first , note that the ideal initial and target states , the fock state @xmath45 and the coherent - state superposition @xmath46 , become identical when @xmath47 . |
6,180 | Suppose that you have an abstract for a scientific paper: we analyze the influence of spatial orientation on the optical response of hydrogenated silicon quantum wires .
the results are relevant for the interpretation of the optical properties of light emitting porous silicon .
we study ( 111)-oriented wires and compare the present results with those previously obtained within the same theoretical framework for ( 001)-oriented wires [ f. buda , j. kohanoff and m. parrinello , _ phys .
rev .
lett . _ * 69 * , 1272 , ( 1992 ) ] . in analogy with the ( 001)-oriented wires and at variance with crystalline bulk silicon
, we find that the ( 111)-oriented wires exhibit a direct gap at @xmath0 whose value is largely enhanced with respect to that found in bulk silicon because of quantum confinement effects . the imaginary part of the dielectric function , for the external field polarized in the direction of the axis of the wires , shows features that , while being qualitatively similar to those observed for the ( 001 ) wires , are not present in the bulk .
the main conclusion which emerges from the present study is that , if wires a few nanometers large are present in the porous material , they are optically active independently of their specific orientation . = 10000 0.4truecm .
And you have already written the first three sentences of the full article: silicon , one of the most relevant materials from the technological point of view , has excellent electronic properties as a semiconductor . however , in the crystalline form , it does not exhibit good optoelectronic properties because of the indirect gap , in the infrared range , between the valence and the conduction bands , and of the low probability of radiative electron - hole recombination .
however it is possible to modify deeply such properties using a process of electrochemical etching @xcite which produces a material known as light emitting porous silicon ( leps ) .
this form , because of its luminescence properties , is presently the object of great scientific and technological attention @xcite ..
Please generate the next two sentences of the article | in fact , inside this material one can observe some wire structures : the wires are strictly interconnected with each other , and have a mean diameter of a few tens of ngstrom .
quantum confinement of charge carriers seems to be at the origin of the optical characteristics of the material , which are quite different from those of bulk silicon . in the recent past many different theoretical studies @xcite |
6,181 | Suppose that you have an abstract for a scientific paper: it has been proposed that the observed systems of hot super - earths formed _ in situ _ from high - mass disks . by fitting a disk profile to the entire population of kepler planet candidates , chiang & laughlin ( 2013 ) constructed a `` minimum - mass extrasolar nebula '' with surface density profile @xmath0 .
here we use multiple - planet systems to show that it is inconsistent to assume a universal disk profile .
systems with 3 - 6 low - mass planets ( or planet candidates ) produce a diversity of minimum - mass disks with surface density profiles ranging from @xmath1 to @xmath2 ( 5th-95th percentile ) . by simulating the transit detection of populations of synthetic planetary systems designed to match the properties of observed super - earth systems ,
we show that a universal disk profile is statistically excluded at high confidence .
rather , the underlying distribution of minimum - mass disks is characterized by a broad range of surface density slopes .
models of gaseous disks can only explain a narrow range of slopes ( roughly between @xmath3 and @xmath4 ) .
yet accretion of terrestrial planets in a gas - free environment preserves the initial radial distribution of building blocks .
the known systems of hot super - earths must therefore not represent the structure of their parent gas disks and can not have predominantly formed _ in situ_. we instead interpret the diversity of disk slopes as the imprint of a process that re - arranged the solids relative to the gas in the inner parts of protoplanetary disks .
a plausible mechanism is inward type 1 migration of mars- to earth - mass planetary embryos , perhaps followed by a final assembly phase .
[ firstpage ] planetary systems : protoplanetary disks planetary systems : formation solar system : formation .
And you have already written the first three sentences of the full article: the minimum - mass solar nebula ( mmsn ) is built by spreading the mass of the planets in concentric annuli then fitting a function to the distribution .
the original mmsn models produced surface density @xmath5 profiles that scaled with orbital radius @xmath6 as @xmath7 @xcite .
newer mmsn analyses have found solutions of @xmath8 @xcite and @xmath9 @xcite ..
Please generate the next two sentences of the article | the mmsn model almost certainly does not represent the initial conditions from which the planets formed .
it presumes that the current orbital architecture of the solar system reflects the properties of its parent protoplanetary disk . however , the giant planets are thought to have undergone multiple episodes of orbital migration ; first during the gaseous disk phase @xcite and later due to planetesimal - driven migration @xcite . |
6,182 | Suppose that you have an abstract for a scientific paper: aggregation of ice crystals is a key process governing precipitation .
individual ice crystals exhibit considerable diversity of shape , and a wide range of physical processes could influence their aggregation ; despite this we show that a simple computer model captures key features of aggregate shape and size distribution reported recently from cirrus clouds .
the results prompt a new way to plot the experimental size distributions leading to remarkably good dynamical scaling .
that scaling independently confirms that there is a single dominant aggregation mechanism at play , albeit our model ( based on undeflected trajectories to contact ) does not capture its form exactly . .
And you have already written the first three sentences of the full article: it has recently become possible to collect large samples of high resolution cloud particle images in real time , opening up the modelling of cloud dynamics to detailed comparison with nature .
figure 1 shows ice crystal aggregates from a cirrus cloud over the usa , captured by non - contact aircraft - based imaging .
such aggregates can be seen to be comprised of varied rosette ice crystal types , and detailed statistics have recently been published on both the cluster aspect ratios [ _ korolev and isaac _ 2003 ] and size distributions [ _ field and heymsfield _ 2003 ] in cirrus clouds ..
Please generate the next two sentences of the article | such aggregation is a key feature of cloud development in the troposphere and can be quite crucial to the development of precipitation , whether it reaches the ground as snow or melts first to arrive as rain .
the openness of the aggregates significantly accelerates their growth . |
6,183 | Suppose that you have an abstract for a scientific paper: we consider the correlation of two single - particle probability densities @xmath0 at coinciding points @xmath1 as a function of the energy separation @xmath2 for disordered tight - binding lattice models ( the anderson models ) and certain random matrix ensembles .
we focus on the parameter range close but not exactly at the anderson localization transition .
we show that even away from the critical point the eigenfunction statistics exhibit the remnant of multifractality characteristic of the critical states .
this leads to an enhancement of eigenfunction correlations and a corresponding enhancement of matrix elements of the local electron interaction at small energy separations .
this enhancement is accompanied by a depression of correlations at large energy separations , both phenomena being a consequence of the stratification of space into densely packed but mutually avoiding resonance clusters .
we also demonstrate that the correlation function of localized states in a @xmath3-dimensional insulator is logarithmically enhanced at small energy separations provided that @xmath4 .
a simple and general physical picture of all these phenomena is presented . finally by a combination of numerical results on the anderson model and analytical and numerical results for the relevant random matrix theories we identified the gaussian random matrix ensembles that describe the multifractal features both in the metal and in the insulator phases . .
And you have already written the first three sentences of the full article: eigenfunction and spectral statistics in quantum systems with quenched disorder were a subject of intense study @xcite in the context of mesoscopic fluctuations of conductance and density of states ( dos ) , in particular in quantum dots @xcite . for this application
the most relevant is the regime of weak deviation @xcite from the wigner - dyson statistics given by the conventional random matrix theory ( rmt ) @xcite .
disordered multi - channel quantum wires is the most important example of systems where single - particle eigenstates are all localized . here.
Please generate the next two sentences of the article | the statistics of eigenstates require a non - perturbative treatment using the formalism of nonlinear sigma - model @xcite or banded random matrices @xcite .
a special class are systems with the critical , multifractal ( mf ) eigenstate statistics @xcite . |
6,184 | Suppose that you have an abstract for a scientific paper: we present an extensive numerical study of the ferromagnetic kondo lattice model with quantum mechanical @xmath0 core spins .
we treat one orbital per site in one dimension using the density matrix renormalization group and include on - site coulomb repulsion between the electrons .
we examine parameters relevant to manganites , treating the range of low to intermediate doping , @xmath1 . in particular , we investigate whether quantum fluctuations favor phase separation over the ferromagnetic polarons observed in a model with classical core spins .
we obtain very good agreement of the quantum model with previous results for the classical model , finding separated polarons which are repulsive at short distance for finite @xmath2 superexchange @xmath3 .
taking on - site coulomb repulsion into account , we observe phase separation for small but finite superexchange @xmath3 , while for larger @xmath3 polarons are favored in accordance with simple energy considerations previously applied to classical spins .
we discuss the interpretation of compressibilities and present a phase diagram with respect to doping and the @xmath2 superexchange parameter @xmath3 with and without coulomb repulsion . .
And you have already written the first three sentences of the full article: the ferromagnetic kondo lattice model has been widely used as a minimal model to describe some features of the manganites @xcite la@xmath4sr@xmath5mno@xmath6 , la@xmath4sr@xmath7mno@xmath8 , and la@xmath9sr@xmath10mn@xmath11o@xmath12 .
the model contains one itinerant @xmath13 orbital and the @xmath2 core spin at each site .
the @xmath13 electrons are ferromagnetically coupled to the @xmath0 core spins generated by the fully occupied @xmath2 orbitals ..
Please generate the next two sentences of the article | the large ferromagnetic hund s rule coupling leads to the formation of two bands , the lower and the upper kondo band , with the @xmath13 electrons predominantly parallel to the core spins in the lower band .
the core spins strongly influence the mobility of the @xmath13 electrons via double exchange ( de ) . at high hole density |
6,185 | Suppose that you have an abstract for a scientific paper: a simple model of opinion formation dynamics in which binary - state agents make up their opinions due to the influence of agents in a local neighborhood is studied using different network topologies .
each agent uses two different strategies , the sznajd rule with a probability @xmath0 and the galam majority rule ( without inertia ) otherwise ; being @xmath0 a parameter of the system . initially , the binary - state agents may have opinions ( at random ) against or in favor about a certain topic .
the time evolution of the system is studied using different network topologies , starting from different initial opinion densities . a transition from consensus in one opinion to the other is found at the same percentage of initial distribution no matter which type of network is used or which opinion formation rule is used .
social systems , opinion formation , structures and organization in complex systems , computer modeling and simulation . 89.65.-s , 89.75.-k , 05.10.-a .
And you have already written the first three sentences of the full article: recently , there has been a growing interest in the study of complex phenomena appearing in heterogeneous areas different from the traditional fields of research . in particular ,
one of those interesting fields turns to be the application of statistical physics methods to social phenomena . at present discussions of such heterogeneous aspects
can be found in several reviews @xcite ..
Please generate the next two sentences of the article | one of the sociological problems that attracts much attention is the construction of consensus out of some initial condition and different models have been introduced in order to simulate and analyze the dynamics of opinion formation processes @xcite . mainly , opinion formation models are composed by interacting _
agents _ usually represented by the state adopted by certain variables . |
6,186 | Suppose that you have an abstract for a scientific paper: in this paper , we study a regular bardeen black hole as a gravitational lens .
we find the strong deflection limit for the deflection angle , from which we obtain the positions and magnifications of the relativistic images . as an example , we apply the results to the particular case of the supermassive black hole at the center of our galaxy .
pacs numbers : 98.62.sb , 04.70.bw , 04.20.dw keywords : gravitational lensing , black hole physics , regular solutions .
And you have already written the first three sentences of the full article: the subject of gravitational lensing by black holes has received great attention in the last decade , basically due to the strong evidence about the presence of supermassive black holes at the center of galaxies , including ours @xcite .
the study of black hole gravitational lenses can be simplified by using the strong deflection limit , which is an approximate analytical method for obtaining the positions , magnifications , and time delays of the images .
it was introduced by darwin @xcite for the schwarzschild geometry , rediscovered by several authors @xcite , extended to reissner - nordstrm geometry @xcite , and to general spherically symmetric black holes @xcite ..
Please generate the next two sentences of the article | kerr black holes were also analyzed adopting the strong deflection limit @xcite .
numerical studies @xcite were done too . |
6,187 | Suppose that you have an abstract for a scientific paper: the excitation energies and spins of the levels in the yrast superdeformed band of @xmath0hg have been determined from two single - step @xmath1 transitions and the quasi - continuum spectrum connecting the superdeformed and normal - deformed states .
the results are compared with those from theoretical mean - field calculations with different interactions .
a discussion of pairing in superdeformed states is also included . 2 .
And you have already written the first three sentences of the full article: a comprehensive understanding of superdeformed ( sd ) bands requires knowledge of the quantum numbers ( spin and parity ) and excitation energies of the levels in the second well .
in particular , these quantities allow for stringent tests of configuration assignments and , more importantly , of the ability of theory to calculate shell - correction energies at large deformation .
however , although more than 250 sd bands are known in the a=150 and 190 regions@xcite , only a few sd bands in @xmath2hg@xcite , @xmath2pb@xcite , @xmath3pb@xcite and in @xmath4dy@xcite , have the spins and excitation energies determined through one - step linking transitions ..
Please generate the next two sentences of the article | the yrast sd band in @xmath0hg was the first one to be discovered in the @xmath5 region @xcite .
it is especially interesting to obtain the spins and excitation energies for an odd - a sd band which , combined with data on neighboring even - even nuclei , can give information on the relative pair correlation energies in normal - deformed ( nd ) and superdeformed ( sd ) states . so far , the main information on single - particle configurations has come from detailed analyses of the @xmath6 dynamic moments of inertia of the sd bands . with a knowledge of the level energies and the associated quantum numbers , |
6,188 | Suppose that you have an abstract for a scientific paper: we report on experiments exploring the physics of dipolar quantum gases using a @xmath0cr bose - einstein condensate ( bec ) . by means of a feshbach resonance ,
it is possible to reduce the effects of short range interactions and reach a regime where the physics is governed by the long - range , anisotropic dipole - dipole interaction between the large ( @xmath1 ) magnetic moments of chromium atoms .
several dramatic effects of the dipolar interaction are observed : the usual inversion of ellipticity of the condensate during time - of flight is inhibited , the stability of the dipolar gas depends strongly on the trap geometry , and the explosion following the collapse of an unstable dipolar condensate displays @xmath2-wave like features . .
And you have already written the first three sentences of the full article: although quantum gases are very dilute systems , most of their properties are governed by atomic interactions .
this allows to use them , for example , as _ quantum simulators _ to study the many - body physics of systems usually encountered in condensed matter physics @xcite .
however , in all usual quantum gases , the interactions can be described extremely well by a short range , isotropic _ contact _ potential , whose magnitude is proportional to the @xmath3-wave scattering length @xmath4 characterizing low energy collisions ..
Please generate the next two sentences of the article | the dipole - dipole interaction taking place between particles having a permanent electric or magnetic dipole moment has radically different properties : it is long - range and anisotropic , as one readily sees on the expression @xmath5 giving the interaction energy @xmath6 between two polarized dipoles separated by @xmath7 ( @xmath8 is the angle between @xmath7 and the direction along which the dipoles are pointing ) .
these specific properties have attracted a lot of interest recently , and a large number of theoretical predictions have been made concerning dipolar quantum gases ( see e.g. ref . for a review ) : for instance , the stability of a dipolar bec depends crucially on the trap geometry ( see section [ sec : stab ] below ) ; in a quasi two - dimensional trap , the excitation spectrum can display a roton minimum instead of the usual bogoliubov shape ; finally , fascinating new quantum phases ( including supersolids ) are predicted to occur for dipolar bosons in an optical lattice . in practice one |
6,189 | Suppose that you have an abstract for a scientific paper: theoretical frameworks to estimate the tolerance of metabolic networks to various failures are important to evaluate the robustness of biological complex systems in systems biology . in this paper , we focus on a measure for robustness in metabolic networks , namely , the _ impact degree _ , and propose an approximation method to predict the probability distribution of impact degrees from metabolic network structures using the theory of branching process .
we demonstrate the relevance of this method by testing it on real - world metabolic networks .
although the approximation method possesses a few limitations , it may be a powerful tool for evaluating metabolic robustness .
metabolic network , branching process , power law , cascading failure 89.75.hc , 89.75.da .
And you have already written the first three sentences of the full article: robustness is a key feature in the analysis of complex systems , especially for complex biological systems .
many organisms have strong adaptability to environmental changes or failures in some of their components , and can live even if some of their genes are mutated . in particular , it is known that cancer cells are very robust @xcite .
therefore , understanding the origin of robustness of living cells has become an important research topic ..
Please generate the next two sentences of the article | in particular , extensive studies have focused on the analysis of structural robustness of metabolic networks .
structural robustness refers to the tolerance of the system s behavior to changes in the structure of networks , and most existing studies focus on changes caused by knockout of gene(s ) or enzyme(s ) . |
6,190 | Suppose that you have an abstract for a scientific paper: we investigate a one - dimensional electron liquid with two point scatterers of different strength . in the presence of electron interactions ,
the nonlinear conductance is shown to depend on the current direction .
the resulting asymmetry of the transport characteristic gives rise to a ratchet effect , i.e. , the rectification of a dc current for an applied ac voltage . in the case of strong repulsive interactions , the ratchet current grows in a wide voltage interval with decreasing ac voltage . in the regime of weak
interaction the current - voltage curve exhibits oscillatory behavior .
our results apply to single - band quantum wires and to tunneling between quantum hall edges
. ratchets , luttinger liquids , conductance , current rectification , bosonization , impurity scattering , hartree approximation .
And you have already written the first three sentences of the full article: systems with asymmetric transport characteristics are also known as ratchets and brownian motors since they can be used to generate dc currents from an ac or noisy voltage .
this mechanism has important applications in physics and biology @xcite . as specific examples , we mention diodes and photovoltaic current rectifiers . here
we address the possibility of realizing such effects in luttinger liquids , which is of interest in connection with nanostructured devices ..
Please generate the next two sentences of the article | motivated by recent experiments on quantum dots @xcite , carbon nanotubes @xcite , and quantum hall systems @xcite , we examine ratchet effects caused by two unequal constrictions as point scatterers .
we consider a one - dimensional spinless electron liquid at zero temperature subject to an impurity potential @xmath0 and a pair interaction @xmath1 with the hamiltonian @xmath2 the impurity potential @xmath0 is chosen to describe two unequal point scatterers at a distance @xmath3 . in the absence of interactions , the application of a voltage @xmath4 leads to a current @xmath5 with a finite conductance @xmath6 . |
6,191 | Suppose that you have an abstract for a scientific paper: we show that gated bilayer graphene zigzag ribbons possess a fast and a slow edge , characterized by edge state velocities that differ due to non - negligible next - nearest - neighbor hopping elements . by applying bosonization and renormalization group methods , we find that the slow edge can acquire a sizable interaction - induced gap , which is tunable via an external gate voltage @xmath0 .
in contrast to the gate - induced gap in the bulk , the interaction - induced gap depends non - monotonously on the on - site potential @xmath1 . .
And you have already written the first three sentences of the full article: one of the most attractive properties of bilayer graphene ( which is made of two coupled atomic layers of carbon ) is the ability to induce a tunable spectral gap @xmath2 by applying a perpendicular electric field .
@xcite rapid advances in patterning graphene on the nanoscale now make it feasible to fabricate graphene ribbons with well defined edge termination , @xcite while experiments on narrow ribbons show that they can display a gap @xmath3 due to transverse size quantization . @xcite the ensuing facility to confine electrons in a controllable way via gate potentials and patterning makes bilayer nanoribbons a promising candidate for nanoelectronic applications .
systems suitable of being used as a basis for a transistor should exhibit a high resistance in the off state . in the case of nanoribbons with zigzag termination.
Please generate the next two sentences of the article | , however , this requirement poses a problem , since the edges support current - carrying states with energies inside the bulk gap , and a much reduced hybridization gap @xmath4 due to exponentially small tunneling between the edges .@xcite on the other hand , several novel concepts ( notably , valleytronics @xcite ) exploit the existence and specific properties of such edge states .
( color online ) upper panel : sketch of a bilayer graphene nanoribbon of lattice constant @xmath5 and width @xmath6 ( inset : definition of hopping terms ) . |
6,192 | Suppose that you have an abstract for a scientific paper: in this paper we employ two distinct approaches - all - electron _ ab initio _ method and the spherical jellium background model- within time dependent density functional theory to calculate the long range dipole - dipole dispersion coefficient ( van der waals coefficient ) @xmath0 of sodium atom clusters containing even number of atoms ranging from 2 to 20 atoms .
the dispersion coefficients are obtained via casimir - polder relation .
all the calculations are carried out with local density approximation for exchange - correlation energy functional .
these two sets of results are compared to assess the accuracy of jellium based results and to ascertain the effect of detail ionic structure of the clusters on the van der waals coefficient . .
And you have already written the first three sentences of the full article: contribution of long - range dispersive van der waals forces to the interaction between two molecules is quite significant .
these forces play an important role in the description of many physical and chemical phenomena .
some of these are adhesion , surface tension , physical adsorption @xcite , chemistry of rare gases @xcite , molecular chemistry in the interstellar medium @xcite etc .. the correlation between the electron density fluctuation at widely separated locations give rise to these forces . the van waals interaction between two molecules a and b in the lowest order.
Please generate the next two sentences of the article | is represented by the orientationally averaged potential @xmath1 where r is the intermolecular distance and c@xmath2 is the orientationally averaged van der waals coefficient .
the coefficient c@xmath2 describes the dipole - dipole interactions between the two molecular species . |
6,193 | Suppose that you have an abstract for a scientific paper: long needle - shaped single crystals of zn@xmath0co@xmath1o were grown at low temperatures using a molten salt solvent technique , up to @xmath2 .
the conduction process at low temperatures is determined to be by mott variable range hopping .
both pristine and cobalt doped crystals clearly exhibit a crossover from negative to positive magnetoresistance as the temperature is decreased .
the positive magnetoresistance of the zn@xmath0co@xmath1o single crystals increases with increased co concentration and reaches up to 20 % at low temperatures ( 2.5 k ) and high fields ( @xmath31 t ) .
squid magnetometry confirms that the zn@xmath0co@xmath1o crystals are predominantly paramagnetic in nature and the magnetic response is independent of co concentration .
the results indicate that cobalt doping of single crystalline zno introduces localized electronic states and isolated co@xmath4 ions into the host matrix , but that the magnetotransport and magnetic properties are decoupled . .
And you have already written the first three sentences of the full article: due to a predicted high curie temperature ( above 300 k ) , diluted magnetic semiconductors ( dms ) are regarded as important materials for spintronics .
@xcite combining ferromagnetism with semiconductivity in oxides gives them an additional degree of freedom and functionality for fabricating unique devices with applications ranging from nonvolatile memory to quantum computing .
@xcite some theoretical @xcite and experimental @xcite reports have shown room temperature ferromagnetism ( rtfm ) in highly doped zno films ..
Please generate the next two sentences of the article | the magnetic impurities are either implanted into the host matrix @xcite or introduced during the growth .
@xcite the experimental results regarding rtfm and its origin in zn@xmath0co@xmath1o samples in different forms including thin films , bulk , polycrystalline and nanocrystalline samples differ widely , and there is no consensus on either the nature of the magnetism ( whether the samples are para- , dia- or ferro - magnetic ) or on the origin of the ferromagnetism ( intrinsic , extrinsic , defect induced etc . ) . in the case of cobalt doped |
6,194 | Suppose that you have an abstract for a scientific paper: we show that contrary to the claim made by hallin and liljenberg in phys . rev .
1150,(1995 ) , ( hep - th/9412188 ) the thermal correction to the _ thermal decay or pair production rate _ for a system placed in a heat bath in the presence of an external electric field , is always nonzero in the finite as well as infinite time limit . using the formalism outlined there ,
we reestimate the decay rate for different values of temperature , mass and time.we also try to identify the parameter ranges where the quantity of interest agrees with that computed previously , at high temperature ( in the infinite time limit ) , from the imaginary part of the effective action using imaginary time and real time formalism of thermal field theory .
we also point out that in the strictly infinite time limit , the correct decay rate as obtained from the work of hallin et .
al . tends to diverge .
= 0.25 cm = 0.25 cm * comment on fermionic and bosonic pair - creation in an external electric field at finite temperature * + [ 16pt ] avijit kumar ganguly + centre for theoretical studies + indian institute of science , bangalore 560012 + .
And you have already written the first three sentences of the full article: the study of pair - creation phenomena in the presence of an external field in a heat bath has attracted some attention in the last few years
. there have been attempts to find out the temperature dependence of the decay rate by various groups ( see for instance references @xcite to @xcite ) .
+ there exists many formalisms to calculate the pair - production rate for such a system ..
Please generate the next two sentences of the article | one of them is to calculate the effective action , the imaginary part of which is related to the vacuum persistence probability and the other is to compute the density matrix using functional schrdinger representation and from thence calculate the production rate . in the past , there had been investigations where the imaginary part of the effective action was calculated using the real time formalism or thermo field dynamics ( tfd)@xcite and also the imaginary time formalism @xcite of finite temperature field theory . on the other hand j.hallin and per liljenberg had derived the vacuum persistence probability for such a system employing the elegant approach of functional schrdinger representation in reference @xcite .
unfortunately the results of these investigations do not see to agree with each othre . some of the studies have found a finite thermal correction to the production amplitude whereas other studies have claimed to have not found any . in references @xcite and @xcite a thermal correction to the decay rate have been found and the results of the two almost match except for a probable typographical error . |
6,195 | Suppose that you have an abstract for a scientific paper: we study the extension of minimal supersymmetric standard model by adding one singlet and one hypercharge zero su(2 ) triplet chiral superfield .
the triplet sector gives an additional contributions to the scalar masses and we find that the lightest cp - even higgs boson can have a mass of 119 - 120 gev at the tree level , and radiative correction raises the value to 125 gev . in this model
no significant contributions from stop loops is needed to get the required higgs mass which alleviates the fine tuning problem of fixing the stop mass to a high precision at the gut scale .
in addition this model gives a neutralino dark matter of mass around 100 gev which is a mixture of higgsino and triplino with a dark matter density consistent with wmap observations .
the spin - independent scattering cross - section with nucleons is @xmath0 , which makes it consistent with the bounds from direct detection experiments like xenon100 and others . .
And you have already written the first three sentences of the full article: the atlas and cms collaborations @xcite have narrowed down the allowed range of a light higgs mass to the region 115 - 131 gev .
in addition there are hints of the higgs mass being near @xmath1gev with sm like decay widths into @xmath2 and @xmath3 .
a light higgs is favored in supersymmetry although the mssm predicts a tree level upper bound on the lightest cp - even higgs mass as @xmath4 . within mssm , loop corrections can give required large corrections to higgs mass provided the stop is heavier than 1 tev or there is near maximal stop mixing ..
Please generate the next two sentences of the article | implications of the 125 gev higgs for the mssm and constrained - mssm parameter space have been extensively studied @xcite .
going beyond mssm , in order to get a larger tree - level higgs mass , the simplest extension is a singlet superfield in the nmssm model @xcite . |
6,196 | Suppose that you have an abstract for a scientific paper: in the coulomb gauge of nonabelian gauge theories there are in general , in individual graphs , ` energy - divergences ' on integrating over the loop energy variable for fixed loop momentum .
these divergences are avoided in the hamiltonian , phase - space formulation .
but , even in this formulation , energy - divergences re - appear at 2-loop order .
we show in an example how these cancel between graphs as a consequence of ward identities .
+ pacs numbers : 11.15.bt ; 11.10.gh + keywords : coulomb gauge ; renormalization ; qcd .
And you have already written the first three sentences of the full article: in gauge theories , the coulomb gauge has special position .
the number of dynamical variables is the same as the number of physical degrees of freedom . moreover ,
if we go to the hamiltonian , phase - space , first - order formalism , there are no ghosts ; and , because of the existence of a hamiltonian , unitarity should be manifest ..
Please generate the next two sentences of the article | nevertheless , there are complications , if not problems , with the coulomb gauge . in the lagrangian , second - order , formalism , there are ` energy - divergences ' in individual feynman graphs
. these are divergences over the energy - integration , @xmath0 , in a loop , for fixed values of the 3-momentum @xmath1 . |
6,197 | Suppose that you have an abstract for a scientific paper: in mixing highly viscous materials , like polymers , foods , and rubbers , the geometric structure of the mixing device is a determining factor for the quality of the mixing process . in pitched - tip kneading disks ( ptkd ) , a novel type of mixing element , based on conventional kneading disks ( kd ) , the tip angle is modified to change the channel geometry as well as the drag ability of kd .
we discuss the effects of the tip angle in ptkd on mixing characteristics based on numerical simulation of the flow in the melt - mixing zone under different feed rates and a screw rotation speed .
it turns out that the passage of fluid through the high - stress regions increases in ptkd compared to conventional kd regardless of the directions and sizes of the tip angle , while the fluctuation in residence time stays at the same level as the conventional kd .
furthermore , pitched tips of backward direction increase the mean applied stress on the fluid elements during its residence in the melt - mixing zone , suggesting the enhancement of dispersive mixing quality in ptkd .
these understandings of the role of the tip angle on kd can give a basic guide in selecting and designing suitable angle parameters of ptkd for different mixing purposes .
polymer processing , mixing , twin - screw extrusion , numerical simulation .
And you have already written the first three sentences of the full article: twin - screw devices are widely applied in various industries , including polymer processing , rubber compounding , food processing , and pharmaceutical development , because a high mixing performance can be achieved by the inter - meshing configuration of twin screws @xcite . in the plastics industry ,
twin - screw extruders are used to develop polymer materials with certain desired properties by mixing different fillers and additives with polymer melts . for this melt - mixing process
, several types of screw elements have been developed for different material processabilities and different mixing qualities , since the quality of the mixing process is primarily determined by the geometric structure of the mixing element . in selecting and/or developing a mixing element ,.
Please generate the next two sentences of the article | one fundamental issue is a systematic understanding of the relation between the melt flow driven by the geometric structure of the mixing element and the mixing characteristics . among various types of mixing elements @xcite ,
kneading disks ( kd ) are the most commonly used due to their mixing efficiency . in order to tune the mixing characteristics of conventional kd for application to various purposes , |
6,198 | Suppose that you have an abstract for a scientific paper: long - duration gamma - ray bursts ( grbs ) provide a premier tool for studying high - redshift star - forming galaxies thanks to their extreme brightness and association with massive stars . here
we use grbs to study the galaxy mass - metallicity ( @xmath0-@xmath1 ) relation at @xmath2 , where conventional direct metallicity measurements are extremely challenging .
we use the interstellar medium metallicities of long - duration grb hosts derived from afterglow absorption spectroscopy ( @xmath3 z@xmath4 ) , in conjunction with host galaxy stellar masses determined from deep _ spitzer _ 3.6 @xmath5 m observations of 20 grb hosts .
we detect about 1/4 of the hosts with @xmath6 to @xmath7 mag , and place a limit of @xmath8 mag on the remaining hosts from a stacking analysis . using a conservative range of mass - to - light ratios for simple stellar populations ( with ages of 70 myr to @xmath9 gyr ) ,
we infer the host stellar masses and present the galaxy mass - metallicity measurements at @xmath2 ( @xmath10 ) .
we find that the detected grb hosts , with @xmath11 m@xmath4 , display a wide range of metallicities , but that the mean metallicity at this mass scale , @xmath12 z@xmath4 , is lower than measurements at @xmath13 . combined with stacking of the non - detected hosts ( with @xmath14 m@xmath4 and @xmath15 z@xmath4 )
, we find evidence for the existence of an @xmath0-@xmath1 relation at @xmath16 and continued evolution of this relation to systematically lower metallicities from @xmath17 .
address = harvard - smithsonian center for astrophysics , 60 garden street , cambridge , ma 02138 address = harvard - smithsonian center for astrophysics , 60 garden street , cambridge , ma 02138 address = spitzer science center , california institute of technology , pasadena , ca 91125 .
And you have already written the first three sentences of the full article: the simple `` closed - box '' model of galaxy evolution @xcite predicts a correlation between the stellar mass and the gas - phase metallicity of a galaxy ( the @xmath0-@xmath1 relation ) .
such a relation is indeed seen in the nearby universe @xcite . and is found to be in place out to @xmath18 @xcite , progressively evolving to lower metallicities . tracing the @xmath0-@xmath1 relation and its evolution to even earlier times will provide insight into the earliest epochs of galaxy evolution , while allowing us to probe the relative importance of various galactic - scale phenomena proposed at @xmath13 .
however , studying the @xmath0-@xmath1 relation beyond @xmath16 is challenging because the nebular emission lines required for robust metallicity measurements ( e.g. , h@xmath19 , h@xmath20 , n@xmath21ii @xmath22 , o@xmath21iii @xmath23 , o@xmath21ii @xmath24 ) shift into different near- and mid - ir wavebands , where existing spectrographs have reduced sensitivity compared to the optical band ..
Please generate the next two sentences of the article | this is aggravated by the faintness of the galaxies , making individual abundance measurements nearly impossible . an alternative way to determine metallicities at @xmath25 ( and in principle at @xmath26 and beyond @xcite )
is absorption spectroscopy of gamma - ray burst ( grb ) optical / near - ir afterglows . |
6,199 | Suppose that you have an abstract for a scientific paper: eugenio regazzini was born on august 12 , 1946 in cremona ( italy ) , and took his degree in 1969 at the university `` l. bocconi '' of milano .
he has held positions at the universities of torino , bologna and milano , and at the university `` l. bocconi '' as assistant professor and lecturer from 1974 to 1980 , and then professor since 1980 .
he is currently professor in probability and mathematical statistics at the university of pavia . in the periods
19892001 and 20062009 he was head of the institute for applications of mathematics and computer science of the italian national research council ( c.n.r . ) in milano and head of the department of mathematics at the university of pavia , respectively . for twelve years between 1989 and 2006 , he served as a member of the scientific board of the italian mathematical union ( u.m.i . ) . in 2007 , he was elected fellow of the ims and , in 2001 , fellow of the `` istituto lombardo accademia di scienze e lettere . ''
his research activity in probability and statistics has covered a wide spectrum of topics , including finitely additive probabilities , foundations of the bayesian paradigm , exchangeability and partial exchangeability , distribution of functionals of random probability measures , stochastic integration , history of probability and statistics .
overall , he has been one of the most authoritative developers of de finetti s legacy . in the last five years
, he has extended his scientific interests to probabilistic methods in mathematical physics ; in particular , he has studied the asymptotic behavior of the solutions of equations , which are of interest for the kinetic theory of gases .
the present interview was taken in occasion of his 65th birthday . . .
And you have already written the first three sentences of the full article: * antonio : * you received your degree in economics from `` l. bocconi '' university in milano
. why did you decide to study economics ?
* eugenio : * i enrolled in an economics degree essentially because it was the only choice i had ..
Please generate the next two sentences of the article | having attended a technical high school for accountants , at the time the law did not allow students from this kind of secondary school to study mathematics at university , which would have been my favorite option .
you needed to attend college preparatory schools to enroll in subjects like mathematics . |
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