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9,800 | Suppose that you have an abstract for a scientific paper: we review the one - loop effective action in scalar qed and the schwinger effect in a uniform electric field in a two - dimensional ( anti- ) de sitter space .
the schwinger effect has a thermal interpretation in terms of the effective temperature introduced by cai and kim .
we propose a method to find the density of states for the charged scalar and obtain the qed action density and the pair - production rate in the in - out formalism . .
And you have already written the first three sentences of the full article: the de sitter ( ds ) and anti - de sitter ( ads ) space has a constant curvature with the maximal symmetry of a given dimension .
the ( a)ds has thus attracted attention in understanding a quantum nature of spacetime and been applied to different physics . the present accelerating universe with a cosmological constant is an asymptotically pure ds space and the early inflationary universe also underwent a quasi - exponential expansion .
the pure ds space has a cosmological horizon and emits the ds radiation with the gibbons - hawking temperature.@xcite the einstein equation for the ds space can be explained by the black hole thermodynamics.@xcite an intriguing feature of the ds radiation is the solitonic nature in the global coordinates in any odd - dimensional ds space.@xcite the discrimination of dimensions for ds radiation can be explained by the stokes phenomenon , in which a pair of instanton actions interferes destructively in odd dimensions and constructively in even dimensions.@xcite the stokes phenomenon can also be explained by the coherent destructive or constructive interference of the superadiabatic particle number.@xcite the one - loop effective action in an electromagnetic field and in a curved spacetime reveals the interplay between quantum electrodynamics ( qed ) and quantum nature of curved spacetime ..
Please generate the next two sentences of the article | a strong electromagnetic field changes the quantum vacuum structure,@xcite and an electric field with / without a parallel magnetic field pulls out virtual particles from the dirac sea and creates pairs of particles and antiparticles known as the schwinger effect.@xcite the schwinger effect in ( a)ds space entails the pair production by the electric field and the ds radiation@xcite or the suppression by the negative curvature of ads space.@xcite the one - loop effective action and the schwinger effect has been comprehensively studied in ref . .
the @xmath0-wave of a scalar field in the nariari geometry of a rotating ds black hole is equivalent to a charge in a uniform electric field in @xmath1.@xcite interestingly , the near - horizon geometry @xmath2 of an extremal or near - extremal black hole deduces that the emission of charges from the black hole is related to the schwinger effect in @xmath3.@xcite the fermionic current due to the schwinger effect@xcite and the holographic schwinger effect@xcite have been studied in the ds space . the production of particles can be explained by the ( effective ) temperature . |
9,801 | Suppose that you have an abstract for a scientific paper: quantum transport properties are instrumental to understanding quantum coherent transport processes
. potential applications of quantum transport are widespread , in areas ranging from quantum information science to quantum engineering , and not restricted to quantum state transfer , control and manipulation . here , we study light transport in a ring array of coupled resonators enclosed synthetic magnetic flux .
the ring configuration , with an arbitrary number of resonators embedded , forms an two - arm aharonov - bohm interferometer .
the influence of magnetic flux on light transport is investigated .
tuning the magnetic flux can lead to resonant transmission , while half - integer magnetic flux quantum leads to completely destructive interference and transmission zeros in an interferometer with two equal arms .
quantum transport , coupled resonators , synthetic magnetic field , aharonov - bohm flux .
And you have already written the first three sentences of the full article: coherent transport in discrete low - dimensional mesoscopic quantum systems has attracted much attentions for fundamental physics as well as applications due to persistent technique progress in nanofabrication @xcite . quantum interference phenomena and quantum coherent transport properties
are extensively investigated in various quantum devices @xcite , interesting effects including fano resonance @xcite , kondo effect @xcite , aharonov - bohm ( ab ) effect @xcite , have been theoretically predicted and experimentally verified in one - dimensional nanostructures system , such as photonic nanocrystals @xcite , nanowires @xcite , quantum dots array @xcite .
much effort has been devoted to investigate coherent electron transport properties of a various types of interferometers oriented at different geometries @xcite . among these ,.
Please generate the next two sentences of the article | quantum dots embedded two - arm electron wave interferometers are mostly studied , in particular , the ab interferometer @xcite .
the ab interferometer is composed by a two - terminal structure with single or double quantum dots embedded . |
9,802 | Suppose that you have an abstract for a scientific paper: a new approximation scheme , designed to solve the covariant maxwell equations inside a rotating hollow slender conducting cavity ( modelling a ring - laser ) , is constructed .
it is shown that for well - defined conditions there exist te and tm modes with respect to the longitudinal axis of the cavity .
a twisted mode spectrum is found to depend on the integrated frenet torsion of the cavity and this in turn may affect the sagnac beat frequency induced by a non - zero rotation of the cavity .
the analysis is motivated by attempts to use ring - lasers to measure terrestrial gravito - magnetism or the lense - thirring effect produced by the rotation of the earth . .
And you have already written the first three sentences of the full article: in 1893 and 1897 lodge argued that a device using electromagnetic fields should in principle be able to detect angular acceleration by the interference of light .
sixteen years later sagnac @xcite observed such an effect and realised the potential for light interferometers as accelerometers .
the continued development of such instruments and their careful exploitation by michelson and others was pivotal in the establishment of our current world view of classical physics ..
Please generate the next two sentences of the article | sagnac recognised that his observations could open up new avenues in the development of accelerometers , an insight that has been dramatically verified . today
the ring - laser is a cornerstone of most inertial guidance systems and optoelectronics is the backbone of the communications industry ( see @xcite for historical accounts of ring - laser development ) . |
9,803 | Suppose that you have an abstract for a scientific paper: we consider the conductance of a quantum tube connected to a metallic contact . the number of angular momentum states that the tube can support depends on the strength of the radial confinement .
we calculate the transmission coefficients which yield the conductance via the landauer formula , and discuss the relation of our results to armchair carbon nanotubes embedded in a metal . for al and au contacts and tubes with a realistic radial confinement
we find that the transmission can be close to unity corresponding to a contact resistance close to @xmath0 per band at the fermi level in the carbon nanotube .
[ firstpage ] .
And you have already written the first three sentences of the full article: since the recent discovery of the carbon nanotubes by iijima @xcite there has been a significant progress @xcite in the studies of the conducting properties of both single - walled @xcite and multi - walled @xcite carbon nanotubes .
conductance of a mesoscopic system connected to metallic reservoirs is well understood and is usually described by the landauer formula @xcite . for quantum point contacts in semiconductor structures and in metallic nanowires
it is well establish experimentally that the differential conductance to a good approximation is quantized in units of @xmath1 and at zero temperature given by @xmath2 where @xmath3 is the number of propagating modes . in carbon nanotubes with metallic contacts.
Please generate the next two sentences of the article | most experiments show that the conductance is less than the conductance which one should expect for a smooth interface between tube and metal , e.g. @xmath4 for metallic single - walled tubes where the extra factor of 2 comes from the two @xmath5 bands that are crossing the fermi level @xcite .
the reasons for this lower conductance are still not fully known . |
9,804 | Suppose that you have an abstract for a scientific paper: we show there exists a linear function @xmath0 with the following property .
let @xmath1 be a hyperbolic knot in a hyperbolic @xmath2manifold @xmath3 admitting a non - longitudinal @xmath4 surgery . if @xmath1 is put into thin position with respect to a strongly irreducible , genus @xmath5 heegaard splitting of @xmath3 then @xmath1 intersects a thick level at most @xmath6 times .
typically , this shows that the bridge number of @xmath1 with respect to this heegaard splitting is at most @xmath7 , and the tunnel number of @xmath1 is at most @xmath8 . .
And you have already written the first three sentences of the full article: let @xmath9 be the manifold obtained by @xmath10-dehn surgery on a knot @xmath11 in @xmath4 .
( here @xmath12 , @xmath13 , parametrizes the slope on the boundary of the exterior of @xmath11 that runs @xmath14 times meridionally and @xmath15 times longitudinally around @xmath11 . )
we denote the core of the attached solid torus in @xmath16 by @xmath1 ..
Please generate the next two sentences of the article | thus @xmath1 is a knot in @xmath3 with a dehn surgery that yields @xmath4 , and it is natural to investigate what properties of @xmath1 this entails . in the present paper
we are interested in the relationship between @xmath1 and the heegaard splittings of @xmath3 ; more specifically , if @xmath17 is a heegaard surface for @xmath3 , what can we say about the bridge number @xmath18 of @xmath1 with respect to @xmath17 ? |
9,805 | Suppose that you have an abstract for a scientific paper: stars form in dense cores of molecular clouds that are observed to be significantly magnetized .
a dynamically important magnetic field presents a significant obstacle to the formation of protostellar disks .
recent studies have shown that magnetic braking is strong enough to suppress the formation of rotationally supported disks in the ideal mhd limit .
whether non - ideal mhd effects can enable disk formation remains unsettled .
we carry out a first study on how disk formation in magnetic clouds is modified by the hall effect , the least explored of the three non - ideal mhd effects in star formation ( the other two being ambipolar diffusion and ohmic dissipation ) . for illustrative purposes
, we consider a simplified problem of a non - self - gravitating , magnetized envelope collapsing onto a central protostar of fixed mass .
we find that the hall effect can spin up the inner part of the collapsing flow to keplerian speed , producing a rotationally supported disk .
the disk is generated through a hall - induced magnetic torque .
disk formation occurs even when the envelope is initially non - rotating , provided that the hall coefficient is large enough .
when the magnetic field orientation is flipped , the direction of disk rotation is reversed as well .
the implication is that the hall effect can in principle produce both regularly rotating and counter - rotating disks around protostars .
we conclude that the hall effect is an important factor to consider in studying the angular momentum evolution of magnetized star formation in general and disk formation in particular . .
And you have already written the first three sentences of the full article: disks are an integral part of star formation ; they are the birthplace of planets .
how they form is a long - standing , unresolved problem .
a major difficulty is that their formation is greatly affected by magnetic braking , which has been hard to quantify until recently ..
Please generate the next two sentences of the article | there is now increasing theoretical evidence that magnetic braking may suppress the formation of rotationally supported disks ( rsds hereafter ) in dense cores magnetized to a realistic level , with dimensionless mass - to - flux ratios @xmath0 of a few to several @xcite .
@xcite first demonstrated through 2d ( axisymmetric ) simulations that rsds are suppressed by a moderately strong magnetic field in the ideal mhd limit . |
9,806 | Suppose that you have an abstract for a scientific paper: using a combination of s - matrix and perturbative qcd properties in the small @xmath0 regime , we propose a formulation of hard diffraction unifying the partonic ( ingelman - schlein ) pomeron , soft colour interaction and qcd dipole descriptions .
in particular , we show that all three approaches give an unique and mutually compatible formula for the proton diffractive structure functions @xmath1 incorporating perturbative and non perturbative qcd features . .
And you have already written the first three sentences of the full article: `` hard diffraction '' is an experimental phenomenon which lies at the borderline between `` hard '' and `` soft '' interactions .
it appears as a scattering process initiated by a hard probe ( e.g. a virtual photon at hera @xcite or a forward jet at the tevatron @xcite ) , but in which the proton target is not destroyed , in a similar way to conventional soft diffractive processes .
it is associated with large rapidity gaps between the hadronic remnants of the target and of the projectile as was discovered at hera , but was first identified by high-@xmath2 jets in diffraction at the isr @xcite ..
Please generate the next two sentences of the article | there has been a lot of debate about the theoretical explanation of hard diffraction . indeed , assuming a partonic content of the pomeron led to a nice prediction @xcite of the phenomenon and , supplemented by the qcd evolution of diffractive structure functions , to a quantitative description of hera data @xcite . as satisfactory as can be this phenomenological analysis ,
the main unsolved problem in this approach is the lack of relation between diffractive and non diffractive hard scattering leading to a profusion of input parameters ( e.g. the non - perturbative parton distributions in the pomeron ) . |
9,807 | Suppose that you have an abstract for a scientific paper: coulombian diffusion determines a dilution of bunching coefficients in free electron laser seeded devices . from the mathematical point of view
the effect can be modeled through a heat type equation , which can be merged with the ordinary liouville equation , ruling the evolution of the longitudinal phase space beam distribution .
we will show that the use of analytical tools like the generalized bessel functions and algebraic techniques for the solution of evolution problems may provide a useful method of analysis and shine further light on the physical aspects of the underlying mechanisms . .
And you have already written the first three sentences of the full article: in this paper we will pursue some technical details concerning the computation and the physical understanding of the recent analysis by stupakov @xcite on the effect of coulomb diffusion on bunching coefficients in echo enabled harmonic generation ( eehg ) free electron laser ( fel ) seeded devices @xcite .
the considerations developed in this paper should be understood as a complement to refs .
@xcite , with the aim of providing a more general computational framework , benefitting from the formalism of beam transport employing algebraic means @xcite . in this treatment.
Please generate the next two sentences of the article | the transport through magnetic elements is treated in terms of exponential operator acting on an initial phase space distribution and usually do not contain transport elements provided by a heat type diffusion . here
we will show that diffusion mechanisms can be included in such a framework in a fairly straightforward way @xcite , preserving the spirit of exponential operator concatenation . |
9,808 | Suppose that you have an abstract for a scientific paper: in search for a foundational framework for reasoning about observable behavior of programs that may not terminate , we have previously devised a trace - based big - step semantics for while . in this
semantics , both traces and evaluation ( relating initial states of program runs to traces they produce ) are defined coinductively . on terminating runs
, this semantics agrees with the standard inductive state - based semantics . here
we present a hoare logic counterpart of our coinductive trace - based semantics and prove it sound and complete .
our logic subsumes the standard partial - correctness state - based hoare logic as well as the total - correctness variation : they are embeddable . in the converse direction
, projections can be constructed : a derivation of a hoare triple in our trace - based logic can be translated into a derivation in the state - based logic of a translated , weaker hoare triple .
since we work with a constructive underlying logic , the range of program properties we can reason about has a fine structure ; in particular , we can distinguish between termination and nondivergence , e.g. , unbounded classically total search fails to be terminating , but is nonetheless nondivergent .
our metatheory is entirely constructive as well , and we have formalized it in coq . .
And you have already written the first three sentences of the full article: standard big - step semantics and hoare logics do not support reasoning about nonterminating runs of programs .
essentially , they ignore them .
but of course nonterminating runs are important ..
Please generate the next two sentences of the article | not only need we often program a partial function whose domain of definedness we can not decide or is undecidable , e.g. , an interpreter , but we also have to program functions that are inherently partial . in programming with interactive input / output , for example , diverging runs are often what we really want . in search for a foundational framework for reasoning about possibly nonterminating programs
constructively ( intuitionistically ) and intrigued by attempts in this direction in the literature , we have previously devised a big - step semantics for while based on traces @xcite . in this |
9,809 | Suppose that you have an abstract for a scientific paper: the curiosity rover recently detected a background of 0.7 ppb and spikes of 7 ppb of methane on mars .
this in situ measurement reorients our understanding of the martian environment and its potential for life , as the current theories do not entail any geological source or sink of methane that varies sub - annually . in particular , the 10-fold elevation during the southern winter
indicates episodic sources of methane that are yet to be discovered .
here we suggest a near - surface reservoir could explain this variability . using the temperature and humidity measurements from the rover , we find that perchlorate salts in the regolith deliquesce to form liquid solutions , and deliquescence progresses to deeper subsurface in the season of the methane spikes .
we therefore formulate the following three testable hypotheses .
the first scenario is that the regolith in gale crater adsorbs methane when dry and releases this methane to the atmosphere upon deliquescence .
the adsorption energy needs to be 36 kj mol@xmath0 to explain the magnitude of the methane spikes , higher than existing laboratory measurements .
the second scenario is that microorganisms convert organic matter in the soil to methane when they are in liquid solutions .
this scenario does not require regolith adsorption , but entails extant life on mars .
the third scenario is that deep subsurface aquifers produce the bursts of methane
. continued _ in situ _ measurements of methane and water , as well as laboratory studies of adsorption and deliquescence , will test these hypotheses and inform the existence of the near - surface reservoir and its exchange with the atmosphere .
mars , methane , astrobiology , regolith .
And you have already written the first three sentences of the full article: methane ( ) is an organic molecule in earth s atmosphere primarily produced by living organisms @xcite .
it has also been measured in mars s atmosphere by telescopic and spacecraft remote sensing @xcite . however , these measurements produced inconsistent results and some of these measurements have been called into question ( e.g. * ? ? ? * ) .
recently , an _ in situ _ measurement of methane on mars has been made : msl s tunable laser spectrometer ( tls ) as a part of the sample analysis at mars ( sam ) instrument determined a background mixing ratio of @xmath1 ppbv and a pulse of @xmath2 ppbv observed over two months @xcite ..
Please generate the next two sentences of the article | these measurements suggest strong temporal variability of the methane abundance on the surface of mars .
methane s atmospheric existence requires a geologically recent or continually replenishing source , because methane has an lifetime of @xmath3 years in mars oxidizing atmosphere @xcite . |
9,810 | Suppose that you have an abstract for a scientific paper: considering the common cause principle , we construct a local - contextual hidden - variable model for the bohm version of epr experiment .
our proposed model can reproduce the predictions of quantum mechanics .
it can be also extended to classical examples in which similar correlations may be revealed . .
And you have already written the first three sentences of the full article: according to bell s theorem [ 1 ] , one can not construct a local realistic hidden - variable theory that can reproduce all the statistical predictions of quantum mechanics for a two - particle singlet - state . here , by the term locality
we mean bell s locality condition which in a local stochastic hidden - variable theory is equivalent to the statistical independence of the values of the spin components of the two particles [ 2 ] .
bell s locality condition at the level of hidden variables also implies a more general tenet named the `` common cause principle '' [ 3 ] . according to this principle.
Please generate the next two sentences of the article | , one can explain how two spatially separated particles can be correlated , when there is no direct causal relationship between them . despite the fact that one can not decisively close the door to other potential alternatives which may provide a better understanding of the so - called bell - type correlations in a causal fashion [ 4 ] , the common cause description is still a very attractive and comprehensible way of understanding the nature of these correlations [ 5 ] .
but , thanks to bell s theorem , we do know that this description can not be compatible with the predictions of quantum mechanics . |
9,811 | Suppose that you have an abstract for a scientific paper: the sun is a variable star whose magnetic activity and total irradiance vary on a timescale of approximately 11 years .
the current activity minimum has attracted considerable interest because of its unusual duration and depth .
this raises the question : what might be happening beneath the surface where the magnetic activity ultimately originates ?
the surface activity can be linked to the conditions in the solar interior by the observation and analysis of the frequencies of the sun s natural seismic modes of oscillation - the @xmath0 modes .
these seismic frequencies respond to changes in activity and are probes of conditions within the sun .
the birmingham solar - oscillations network ( bison ) has made measurements of @xmath0-mode frequencies over the last three solar activity cycles , and so is in a unique position to explore the current unusual and extended solar minimum .
we show that the bison data reveal significant variations of the @xmath0-mode frequencies during the current minimum .
this is in marked contrast to the surface activity observations , which show little variation over the same period .
the level of the minimum is significantly deeper in the @xmath0-mode frequencies than in the surface observations .
we observe a quasi - biennial signal in the @xmath0-mode frequencies , which has not previously been observed at mid- and low - activity levels .
the stark differences in the behavior of the frequencies and the surface activity measures point to activity - related processes occurring in the solar interior , which are yet to reach the surface , where they may be attenuated . .
And you have already written the first three sentences of the full article: the level of the sun s magnetic activity is observed to vary on an 11-year time scale and we are currently in the minimum between cycles 23 and 24 .
the current solar minimum is attracting a great deal of attention as it is proving to be quite unusual .
observations of surface and atmospheric effects , such as the number of visible sunspots , the rate of occurrence of solar flares and the strength of the solar wind , highlight just how quiet the sun is ..
Please generate the next two sentences of the article | the sun s activity cycle influences everyday life on the earth .
the rate of occurrence of solar flares is dependent on the number of spots on the sun s surface , and large solar flares can disrupt satellite communications and cause power outages . |
9,812 | Suppose that you have an abstract for a scientific paper: we calculate the ( parity - violating ) spin rotation angle of a polarized neutron beam through hydrogen and deuterium targets , using pionless effective field theory up to next - to - leading order .
our result is part of a program to obtain the five leading independent low - energy parameters that characterize hadronic parity - violation from few - body observables in one systematic and consistent framework .
the two spin - rotation angles provide independent constraints on these parameters .
our result for @xmath0 spin rotation is @xmath1\ , { \rm rad}\ , { \ensuremath{\mathrm{mev}}}^{-{\frac{1}{2 } } } \ , \left(2{g^{(^3 \ !
s_1-^3 \ ! p_1)}}+{g^{(^3 \
! s_1-^1 \ !
p_1)}}\right ) - [ 18.5 \pm 1.9]\ , { \rm rad } \ , { \ensuremath{\mathrm{mev}}}^{-{\frac{1}{2 } } } \ , \left({g^{(^1 \
! s_0-^3 \ !
p_0)}_{(\delta i=0)}}- 2 { g^{(^1 \ ! s_0-^3 \
! p_0)}_{(\delta i=2)}}\right)$ ] , while for @xmath2 spin rotation we obtain @xmath3\ , { \rm rad } \ , { \ensuremath{\mathrm{mev}}}^{-{\frac{1}{2}}}\;{g^{(^3 \ ! s_1-^1 \ !
p_1)}}\;+\;[17.0\pm1.7]\ , { \rm rad } \ , { \ensuremath{\mathrm{mev}}}^{-{\frac{1}{2}}}\;{g^{(^3 \
! s_1-^3 \ !
p_1)}}+[2.3\pm0.5]\ , { \rm rad } \ , { \ensuremath{\mathrm{mev}}}^{-{\frac{1}{2}}}\;\left(3{g^{(^1 \ ! s_0-^3 \ !
p_0)}_{(\delta i=0)}}-2{g^{(^1 \ !
s_0-^3 \
! p_0)}_{(\delta i=1)}}\right)$ ] , where the @xmath4 , in units of @xmath5 , are the presently unknown parameters in the leading - order parity - violating lagrangian . using nave dimensional analysis to estimate the typical size of the couplings
, we expect the signal for standard target densities to be @xmath6\ ; \frac{\text{rad}}{\text{m } } $ ] for both hydrogen and deuterium targets .
we find no indication that the @xmath2 observable is enhanced compared to the @xmath0 one .
all results are properly renormalized .
an estimate of the numerical and systematic uncertainties of our calculations indicates excellent convergence .
an appendix contains the relevant partial -....
And you have already written the first three sentences of the full article: parity - violating nucleon - nucleon interactions cause the spin of transversely polarized neutrons to undergo a rotation when traveling through a target medium , even in the absence of magnetic fields . in this paper
we report the results of a calculation of neutron spin rotation from neutron - proton and neutron - deuteron forward scattering using pionless effective field theory , eft(@xmath7 ) .
this work is part of an effort to provide one consistent eft(@xmath7)framework with reliable theoretical uncertainties to parity - violating ( pv ) interactions in few - nucleon systems ..
Please generate the next two sentences of the article | we hope that the results presented here , along with the results from refs .
@xcite , will assist in the planning , analysis , and interpretation of related pv experiments . |
9,813 | Suppose that you have an abstract for a scientific paper: relativistic jets carry energy and particles from compact to very large scales compared with their initial radius .
this is possible due to their remarkable collimation despite their intrinsic unstable nature . in this contribution ,
i review the state - of - the - art of our knowledge on instabilities growing in those jets and several stabilising mechanisms that may give an answer to the question of the stability of jets .
in particular , during the last years we have learned that the limit imposed by the speed of light sets a maximum amplitude to the instabilities , contrary to the case of classical jets . on top of this stabilising mechanism ,
the fast growth of unstable modes with small wavelengths prevents the total disruption and entrainment of jets .
i also review several non - linear processes that can have an effect on the collimation of extragalactic and microquasar jets . within those
, i remark possible causes for the decollimation and deceleration of fri jets , as opposed to the collimated frii s .
finally , i give a summary of the main reasons why jets can propagate through such long distances . .
And you have already written the first three sentences of the full article: relativistic jets in agn and microquasars carry energy from very small to very large scales .
these jets form in the surroundings of compact objects , such as neutron stars or stellar black - holes in the case of microquasar jets , and supermassive black - holes ( smbh ) in the case of agn jets .
the forming scales are of the order of a few times to about 30 times the radius of the central object , depending on the forming mechanism.@xcite from these regions , jets propagate up to nine powers of ten in distance ..
Please generate the next two sentences of the article | this implies formidable stability and collimation taking into account that different instabilities can affect the evolution of jets independently of their nature .
moreover , their propagation is possibly changing the properties and evolution of the host galaxies and their environments through heating by shocks and/or mixing , and removing of gas by shocks and transfer of momentum . |
9,814 | Suppose that you have an abstract for a scientific paper: we present a detailed numerical analysis of the modified version of a conservative self - organized extremal model introduced by pianegonda et .
al . for the distribution of wealth of the people in a society . here
the trading process has been modified by the stochastic bipartite trading rule . more specifically in a trade one of the agents is necessarily the one with the globally minimal value of wealth , the other one being selected randomly from the neighbors of the first agent .
the pair of agents then randomly re - shuffle their entire amount of wealth without saving .
this model has most of the characteristics similar to the self - organized critical bak - sneppen model of evolutionary dynamics .
numerical estimates of a number of critical exponents indicate this model is likely to belong to a new universality class different from the well known models in the literature .
in addition the persistence time , which is the time interval between two successive updates of wealth of an agent has been observed to have a non - trivial power law distribution
. an opposite version of the model has also been studied where the agent with maximal wealth is selected instead of the one with minimal wealth , which however , exhibits similar behavior as the minimal wealth model . .
And you have already written the first three sentences of the full article: study of the probability distribution of wealth of the people in a society goes back to 1897 when pareto observed empirically that the distribution is characterized by a power law tail .
probability that an individual member has wealth more than @xmath0 is given by @xmath1 with @xmath2 @xcite .
this type of distribution is known as the pareto distribution @xcite ..
Please generate the next two sentences of the article | this observation reflects the inherent inequality in the economic structure of the society .
a large number of individuals are economically poor . in comparison |
9,815 | Suppose that you have an abstract for a scientific paper: we present a new model for gamma - ray bursts ( grbs ) that are not only associated with supernovae but also have small baryon contamination . in this model , we assume a newborn neutron star to move outward at a kick velocity of @xmath0 in the supernova ejecta .
we find that such a neutron star still hypercritically accretes its surrounding supernova matter . once the stellar mass increases to some critical mass
, the neutron star will undergo a phase transition to become a strange star , leading to an energy release of a few @xmath1 ergs .
the phase transition , if possibly occuring just near the supernova front , will first result in an ultra - relativistic fireball and then a grb .
this provides a plausible explanation for the grb - supernova association .
we estimate the burst rate to be @xmath2 per year per galaxy .
our model also predicts other possiblities .
for example , if the resulting fireballs have a lorentz factor of the order of a few , they will produce x - ray grbs observed by bepposax .
we find the rate of such bursts to be @xmath3 per year per galaxy . .
And you have already written the first three sentences of the full article: gamma - ray bursts ( grbs ) emit an amount of isotropic - equivalent energy @xmath4 ergs in @xmath5-rays and x - rays in a few seconds and subsequently emit afterglows at x - ray ( costa et al . 1997 ) , optical ( van paradijs et al .
1997 ) and radio bands ( frail et al . 1997 ) , which generally last days to months ( van paradijs , kouveliotou & wijers 2000 ) .
the energetics of grbs , which is comparable to that of supernovae , and their rapid variability strongly suggest compact objects involving black holes , neutron stars and strange stars as the energy source for grbs ..
Please generate the next two sentences of the article | two popular models satisfying this energetics are explosive events of very massive stars , also named hypernovae ( paczyski 1998 ) or collapsars ( woosley 1993 ; macfadyen & woosley 1999 ) , and mergers of neutron - star binaries ( eichler et al . 1989 : narayan , paczyski & piran 1992 ) .
other possible models include phase transitions of neutron stars to strange stars ( cheng & dai 1996 ; dai & lu 1998a ; bombaci & datta 2000 ; wang et al . |
9,816 | Suppose that you have an abstract for a scientific paper: we describe a monte carlo event generator for the simulation of qcd - instanton induced processes in deep - inelastic scattering ( hera ) .
the qcdins package is designed as an `` add - on '' hard process generator interfaced to the general hadronic event simulation package herwig .
it incorporates the theoretically predicted production rate for instanton - induced events as well as the essential characteristics that have been derived theoretically for the partonic final state of instanton - induced processes : notably , the flavour democratic and isotropic production of the partonic final state , energy weight factors different for gluons and quarks , and a high average multiplicity @xmath0 of produced partons with a poisson distribution of the gluon multiplicity .
while the subsequent perturbative evolution of the generated partons is always handled by the herwig package , the final hadronization step may optionally be performed also by means of the general hadronic event simulation package jetset . and
qcd ; instanton ; deep - inelastic scattering ; monte carlo simulation 11.15.kc ; 12.38.lg ; 13.60.hb * program summary * + _ title of program : _ qcdins 2.0 + _ catalogue identifier : _ + _ program obtainable from : _
http://www.desy.de/~t00fri/qcdins/qcdins.html + _
computer for which the program is designed and others on which it has been tested : _ any computer with a fortran 77 compiler + _ operating systems under which the program has been tested : _
linux 2.0.x ; hp - ux 10.2 + _ programming language used : _ fortran 77 + _ memory required to execute with typical data : _ size of executable program is approximately 2.6 mb .
the size of the qcdins library itself is about 200 kb ; the required routines from the herwig and jetset libraries constitute the dominant portion of the needed memory .
+ _ no . of processors
used : _ 1 + _ has the code been vectorised or parallelized ? : _ no + _ no . of bytes in distributed program ,
including test data , etc . :
_ 1071106 +....
And you have already written the first three sentences of the full article: the ground state ( `` vacuum '' ) of non - abelian gauge theories like qcd is known to be very rich .
it includes topologically non - trivial fluctuations of the gauge fields , carrying an integer topological charge @xmath1 .
the simplest building blocks of topological structure in the vacuum are @xcite _ instantons _ with @xmath2 and _ anti - instantons _ with @xmath3 ..
Please generate the next two sentences of the article | instantons represent gluon field configurations that are localized ( `` instantaneous '' ) in euclidean time and space .
while they are believed to play an important role in various long - distance aspects of qcd , there are also important short - distance implications . in qcd with @xmath4 ( light ) flavours , instantons induce hard processes violating _ |
9,817 | Suppose that you have an abstract for a scientific paper: a quantitative method is presented for stopping the intrinsic precession of a spherical pendulum due to ellipsoidal motion . removing this unwanted
precession renders the foucault precession due to the turning of the earth readily observable .
the method is insensitive to the size and direction of the perturbative forces leading to ellipsoidal motion .
we demonstrate that a short ( three meter ) pendulum can be pushed in a controlled way to make the foucault precession dominant .
the method makes room - height or table - top foucault pendula more accurate and practical to build . .
And you have already written the first three sentences of the full article: lon foucault built his first pendulum to demonstrate the turning of the earth in the basement of a building , using a roughly two meter long fiber @xcite .
he also soon recognized the problem arising from the intrinsic precession of a spherical pendulum caused by unwanted ellipsoidal motion .
imperfections in the suspension or initial conditions of the pendulum generally cause this to quickly grow to the point that the precession due to the earth s turning is overwhelmed ..
Please generate the next two sentences of the article | the pendulum can come to precess in either sense ( clockwise or counterclockwise ) at almost any rate , or indeed even cease all precession .
these practical problems are mitigated in pendula of great length , and so most are constructed to have lengths of tens of meters , starting with the celebrated 67 m long device built by foucault in paris in 1851 . |
9,818 | Suppose that you have an abstract for a scientific paper: we present an automated method to detect populations of groups in galaxy redshift catalogs .
this method uses both analysis of the redshift distribution along lines of sight in fixed cells to detect elementary structures and a friend - of - friend algorithm to merge these elementary structures into physical structures .
we apply this method to the ssrs2 galaxy redshift catalog .
the groups detected with our method are similar to group catalogs detected with pure friend - of - friend algorithms .
they have similar mass distribution , similar abundance versus redshift , similar 2-point correlation function ( modeled by a power law : @xmath0 with @xmath1 and @xmath2 ) and the same redshift completeness limit , close to 5000 km / s .
if instead of ssrs2 , we use catalogs of the new generation ( deep redshift surveys obtained with 10 meters class telescopes ) , it would lead to a completeness limit of [email protected] .
we model the luminosity function for nearby galaxy groups by a schechter function with parameters m@xmath4=([email protected])+5logh and @[email protected] to compute the mass to light ratio .
the median value of the mass to light ratio is 360 hm@xmath7/l@xmath7 ( in the ssrs2 band , close to a b band magnitude ) and we deduce a relation between mass to light ratio and velocity dispersion @xmath8 ( @xmath9 ) .
the more massive the group , the higher the mass to light ratio , and therefore , the larger the amount of dark matter inside the group .
another explanation is a significant stripping of the gas of the galaxies in massive groups as opposed to low mass groups .
this extends to groups of galaxies the mild tendency already detected for rich clusters of galaxies .
finally , we detect a barely significant fundamental plane for these groups ( @xmath10 for groups with more than 8 galaxies ) but much less narrow than for clusters of galaxies .
galaxies : clusters : general ; cosmology : large - scale structure of universe .
And you have already written the first three sentences of the full article: the abundance evolution of galaxy structures is a major prediction of cosmological models ( e.g. oukbir @xmath11 blanchard 1992 , 1997 , romer et al .
2001 ) . the more distant the structure , the strongest the constraint . until now
, however , we are limited to the study of the most massive distant structures ..
Please generate the next two sentences of the article | this is because these structures are the easiest to detect at high redshift using for example x - ray selected samples ( e.g. borgani et al . 1999 , burke et al .
1997 , ebeling et al . |
9,819 | Suppose that you have an abstract for a scientific paper: we report rapid optical variability for the blazar s5 0716 + 71 during 2010 march 08 - 10 & 19 - 20 in the ccd observations made from mt .
abu infrared observatory .
the light curves are constructed for the duration longer than 3-hours each night , with very high temporal resolution(@xmath0 45 seconds in r - band ) . during 2010 march 08 source smoothly decayed by about 0.15 mag in 2.88 hours , apart from a fast flicker lasting about 30 mins .
s5 0716 + 71 brightened up during march @xmath1 and @xmath2 showing high activity while it was relatively faint ( @xmath3 14 mag in r ) albeit variable during march 19 - 20 . during march 9
& 10 , rapid flickers in the intensity modulate the long term intra - night ( @xmath4 3 hours ) variation .
the present observations suggest that the blazar s5 0716 + 71 showed night - to - night and intra - night variability at various time scales with 100% duty cycle for variation along with microvariability at significant levels . on night - to - night basis ,
the source exhibits mild bluer when brighter nature .
the interaction of shocks with local inhomogeneities in the jet appears to cause intra - night variations while microvariations could be due to small scale perturbations intrinsic to the jet . .
And you have already written the first three sentences of the full article: blazars are an extreme subclass of active galactic nuclei ( agns ) , seen at small angle ( @xmath5 ) to the relativistic jet emanating from very close to the black hole @xcite .
they are characterized by strong variability in flux and polarization at almost all the frequencies in the electromagnetic spectrum and their variability is often used to probe the central engine and nature of physical processes in agns .
blazars are known to show variations on different time scales- ranging from years to months to days to hours and minutes ..
Please generate the next two sentences of the article | the variations which occur during the course of night ( few hours ) are known as intra - night variations ( inov ) while microvariability is few tenths of magnitude change in brightness during hours or less .
some authors use these terms interchangeably @xcite . |
9,820 | Suppose that you have an abstract for a scientific paper: the low cost and high resolution gas - based multi - gap resistive plate chamber ( mrpc ) opens a new possibility to find an efficient alternative detector for time of flight ( tof ) based positron emission tomography , where the sensitivity of the system depends largely on the time resolution of the detector .
suitable converters can be used to increase the efficiency of detection of photons from annihilation . in this work ,
we perform a detailed geant4 simulation to optimize the converter thickness thereby improving the efficiency of photon conversion .
also we have developed a monte carlo based simulation of mrpc response thereby obtaining the intrinsic time resolution of the detector , making it possible to simulate the final response of mrpc - based systems for pet imaging .
the result of the cosmic ray test of a four - gap bakelite - based mrpc operating in streamer mode is discussed . .
And you have already written the first three sentences of the full article: under nuclear medicine , positron emission tomography ( pet ) is an important imaging technique in which a radio - pharmaceutical having positron emitter is injected into the object of study .
this radioactive element can be used to collect the morphological information from the object . inside the object , these positrons annihilate with the available electrons to produce two nearly back - to - back photons each having energy of 511 kev .
the simultaneous detection of these photons with efficient detectors can lead to the identification of annihilation point . as these positron emitters are injected via some physiological substances , mapping of the density of the positron sources.
Please generate the next two sentences of the article | can give the information about the activity inside the object of interest .
although pet gives various important information which the other imaging techniques are not able to provide , limitations due to a short field of view ( fov)(@xmath016 cm in standard pet scanners ) , long dead time of the electronics among others affect the sensitivity and the spatial resolution of the currently available pet scanners . |
9,821 | Suppose that you have an abstract for a scientific paper: a time delay of type ia supernova ( sn ia ) explosions hinders the imprint of their nucleosynthesis on stellar abundances .
however , some occasional cases give birth to stars that avoid enrichment of their chemical compositions by massive stars and thereby exhibit a sn ia - like elemental feature including a very low [ mg / fe ] ( @xmath0 ) .
we highlight the elemental feature of fe - group elements for two low - mg / fe objects detected in nearby galaxies , and propose the presence of a class of sne ia that yield the low abundance ratios of [ cr , mn , ni / fe ] .
our novel models of chemical evolution reveal that our proposed class of sne ia ( slow sne ia ) is associated with ones exploding on a long timescale after their stellar birth , and gives a significant impact on the chemical enrichment in the large magellanic cloud ( lmc ) . in the galaxy , on the other hand , this effect is unseen due to the overwhelming enrichment by the major class of sne ia that explode promptly ( prompt sne ia ) and eject a large amount of fe - group elements .
this nicely explains the different [ cr , mn , ni / fe ] features between the two galaxies as well as the puzzling feature seen in the lmc stars exhibiting very low ca but normal mg abundances .
furthermore , the corresponding channel of slow sn ia is exemplified by performing detailed nucleosynthesis calculations in the scheme of sne ia resulting from a 0.8 + 0.6 white dwarf merger . .
And you have already written the first three sentences of the full article: chemical abundance of long - lived stars is a powerful tool to probe nucleosynthesis in supernovae ( sne ) .
in fact , detailed chemical compositions for very metal - poor stars in the galaxy revealed by pioneering observations ( e.g. , * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ) for more than a decade have brought a remarkable progress in the understanding of nucleosynthesis in core - collapse sne , i.e. , type ii sne ( sne ii ) which first contribute to the chemical enrichment in the universe . on the other hand , owing to a long time delay until the explosion , the nucleosynthesis products from type ia sne ( sne ia ) are unavoidably superimposed on interstellar matter ( ism ) already enriched by numerous sne ii , which prevents us from directly assessing sn ia nucleosynthesis through an analysis of the observed data of stellar abundances |
9,822 | Suppose that you have an abstract for a scientific paper: using data mostly assembled by previous authors , we consider the linear correlation between the apparent radiative efficiency @xmath0 ( defined as the ratio of isotropic equivalent radiative output to inferred isotropic equivalent kinetic energy of the blast ) and @xmath1 where @xmath2 , for 17 of 22 grbs ( lloyd - ronning and zhang , 2004 ) .
we note in a quantitative manner that this is consistent with the hypothesis that @xmath0 and @xmath3 are influenced by viewing angle .
we suggest a more general theoretically derived expression for this correlation that could be tested with a richer data set . if the reduction in both @xmath0 and @xmath3 is due to viewing angle effects , then the actual radiative efficiency is @xmath4 .
we also find preliminary evidence ( with a small sample ) for a separate class of weak grb afterglows . .
And you have already written the first three sentences of the full article: it is well understood that the highly super - eddington luminosities associated with grb are liable to put most of their energy into a baryonic wind if the energy release is in a position to drag matter outward .
one solution for this ( meszaros and rees 1994 ) is that at distances @xmath5 cm from the central burster , internal shocks in a baryonic outflow release some fraction of the bulk expansion energy by accelerating particles , which then radiate @xmath6-rays .
this probably predicts that typically 10 to 50 percent of the energy can be recovered and put back into radiation ..
Please generate the next two sentences of the article | it also predicts that the @xmath6-rays are always accompanied by baryonic outflow along the same direction to within @xmath7 .
alternatively , it may be supposed that the energy release is originally devoid of baryons ( e.g. if the energy emerged along event horizon -threading field lines [ eichler and levinson , 1993 ] ) and the the baryon content of the grb fireball is whatever it swept up subsequently , either from the sides ( eichler and levinson 1999 , levinson and eichler 2003 ) , or from the ambient material into which the fireball expands ( e.g. meszaros and rees 1992 , lyutikov and blandford 2004 ) . if the fireball were able to sweep up ambient material without having any baryons originally , then afterglow would be `` guaranteed '' provided that the ambient medium has sufficient density . |
9,823 | Suppose that you have an abstract for a scientific paper: the spin - exchange effect in spin - polarized electron collisions with unpolarized open - shell molecules , o@xmath0 , b@xmath0 , s@xmath0 and si@xmath0 , has been studied by the r - matrix method with the fixed - bond approximation .
all of these molecules have @xmath1 symmetry in their ground states .
usual integrated cross sections with unpolarized electrons has also been studied .
we used the complete active space self consistent field orbitals and put more than 10 target electronic states in the r - matrix models . in electron o@xmath0 elastic collisions ,
calculated polarization fractions agree well with the experimental results , especially around the @xmath2 resonance . in e - b@xmath0 , s@xmath0 and si@xmath0 elastic collisions ,
larger spin - exchange effect is observed compared to the e - o@xmath0 elastic collisions . in all four cases ,
spin - exchange effect becomes prominent near resonances .
this association of resonance and magnitude of the spin - exchange effect was studied by explicitly removing the resonance configurations from the r - matrix calculations . in general , spin - exchange effect is larger in e - b@xmath0 collisions than in e - s@xmath0 and si@xmath0 collisions , and is smallest in e - o@xmath0 collisions . .
And you have already written the first three sentences of the full article: when electron collides elastically with open - shell atom or molecule , they can exchange their spins .
thus , spin polarization of the electron beam is in general reduced after scattering with unpolarized open - shell targets .
we can obtain more precise information of the scattering process by studying this depolarization @xcite , which is difficult to observe in usual experiment with spin - averaging procedure ..
Please generate the next two sentences of the article | collisions of spin - polarized electrons with atoms have been studied for long years ( see hegemann et al.@xcite and references therein ) .
in contrast , number of experiment on electron molecule system is limited . |
9,824 | Suppose that you have an abstract for a scientific paper: image denoising is an important pre - processing step in medical image analysis .
different algorithms have been proposed in past three decades with varying denoising performances . more recently ,
having outperformed all conventional methods , deep learning based models have shown a great promise .
these methods are however limited for requirement of large training sample size and high computational costs . in this paper
we show that using small sample size , denoising autoencoders constructed using convolutional layers can be used for efficient denoising of medical images .
heterogeneous images can be combined to boost sample size for increased denoising performance .
simplest of networks can reconstruct images with corruption levels so high that noise and signal are not differentiable to human eye .
image denoising , denoising autoencoder , convolutional autoencoder .
And you have already written the first three sentences of the full article: medical imaging including x - rays , magnetic resonance imaging ( mri ) , computer tomography ( ct ) , ultrasound etc .
are susceptible to noise @xcite .
reasons vary from use of different image acquisition techniques to attempts at decreasing patients exposure to radiation . as the amount of radiation is decreased , noise increases @xcite ..
Please generate the next two sentences of the article | denoising is often required for proper image analysis , both by humans and machines .
image denoising , being a classical problem in computer vision has been studied in detail . |
9,825 | Suppose that you have an abstract for a scientific paper: a scattering zipper is a system obtained by concatenation of scattering events with equal even number of incoming and out going channels .
the associated scattering zipper operator is the unitary equivalent of jacobi matrices with matrix entries and generalizes blatter - browne and chalker - coddington models and cmv matrices .
weyl discs are analyzed and used to prove a bijection between the set of semi - infinite scattering zipper operators and matrix valued probability measures on the unit circle .
sturm - liouville oscillation theory is developed as a tool to calculate the spectra of finite and periodic scattering zipper operators . .
And you have already written the first three sentences of the full article: a scattering zipper describes consecutive scattering events with a fixed number @xmath0 of incoming and out - going channels each .
it is specified by a sequence @xmath1 of unitary scattering matrices @xmath2 in the unitary group @xmath3 as well as two unitaries @xmath4 modeling the boundary scattering . the size @xmath5 of the system is supposed to be either even or infinite .
then the scattering zipper operator acting on @xmath6 is defined as @xmath7 where the two unitaries @xmath8 and @xmath9 are given by @xmath10 the main hypothesis on each of the scattering matrices @xmath2 is that its upper right entry of size @xmath11 is invertible . in the notation of section [ sec - prel ] below ,.
Please generate the next two sentences of the article | @xmath2 is in a subset @xmath12 of the unitary group .
this condition assures that the scattering is effective so that @xmath13 does not decouple into a direct sum of two or more parts . |
9,826 | Suppose that you have an abstract for a scientific paper: the annihilations of wimps produce high energy gamma - rays in the final state .
these high energy gamma - rays may be detected by imaging atmospheric cherenkov telescopes ( iacts ) . amongst
the plausible targets are the galactic center , the centre of galaxy clusters , dwarf sphreroidal galaxies and substructures in galactic haloes .
i will review on the recent results from observations of ongoing iacts . .
And you have already written the first three sentences of the full article: cosmological and astrophysical probes suggest that @xmath023% of the universe is composed of non - baryonic dark matter ( dm ) , commonly assumed to be in the form of weakly interacting massive particles ( wimps ) arising in extensions of the standard model of particle physics ( for reviews see , e.g. @xcite ) . amongst
the most widely discussed dm candidates are the lightest neutralino in supersymmetric extensions of the standard model @xcite and the first excitation of the kaluza - klein bosons ( lkp ) in universal extra dimension theories.@xcite the annihilation of wimp pairs can produce in the final state a continuum of gamma - rays whose flux extends up to the dm particle mass , from the hadronization and decay of the cascading annihilation products . in supersymmetric models ,
the gamma - ray spectrum from neutralino annihilation is not uniquely determined and the branching ratios ( brs ) of the open annihilation channels are not determined since the dm particle field content is not known _.
Please generate the next two sentences of the article | a priori_. in contrast , in kaluza - klein scenarios where the lightest kaluza - klein particle ( lkp ) is the first kk mode of the hypercharge gauge boson , the brs of the annihilation channels can be computed given that the field content of the dm particle is known .
the gamma - ray flux from annihilations of dm particles of mass @xmath1 accumulating in a spherical dm halo can be expressed in the form : @xmath2 as a product of a particle physics component with an astrophysics component . |
9,827 | Suppose that you have an abstract for a scientific paper: we compute the critical josephson current through a single - molecule junction . as a model for a molecule with a bistable conformational degree of freedom ,
we study an interacting single - level quantum dot coupled to a two - level system and weakly connected to two superconducting electrodes .
we perform a lowest - order perturbative calculation of the critical current and show that it can significantly change due to the two - level system . in particular , the @xmath0-junction behavior , generally present for strong interactions , can be completely suppressed . .
And you have already written the first three sentences of the full article: the swift progress in molecular electronics achieved during the past decade has mostly been centered around a detailed understanding of charge transport through single - molecule junctions,@xcite where quantum effects generally turn out to be important .
when two _ superconducting _ ( instead of normal ) electrodes with the same chemical potential but a phase difference @xmath1 are attached to the molecule , the josephson effect@xcite implies that an equilibrium current @xmath2 flows through the molecular junction . over the past decade ,
experiments have observed gate - tunable josephson currents through nanoscale junctions , @xcite including out - of - equilibrium cases , and many different interesting phenomena have been uncovered ..
Please generate the next two sentences of the article | in particular , the current - phase relation has been measured by employing a superconducting quantum interference device.@xcite for weakly coupled electrodes , the current - phase relation is@xcite @xmath3 with the _ critical current _ @xmath4 .
the above questions have also been addressed by many theoretical works . |
9,828 | Suppose that you have an abstract for a scientific paper: nanoparticles of rubidium cobalt hexacyanoferrate ( rb@xmath0co@xmath1[fe(cn)@xmath2@xmath3h@xmath4o ) were synthesized using different concentrations of polyvinylpyrrolidone ( pvp ) to produce four different batches of particles with characteristic diameters ranging from 3 to 13 nm . upon illumination with white light at 5 k , the magnetization of these particles increases .
the long - range ferrimagnetic ordering temperatures and the coercive fields evolve with nanoparticle size . at 2 k , particles with diameters less than approximately 10
nm provide a curie - like magnetic signal . .
And you have already written the first three sentences of the full article: the investigation of magnetism in the molecule - based solid prussian blue , fe@xmath5[fe(cn)@xmath2@xmath6h@xmath4o , and related analogs has a rich history @xcite , dating back to 1928 @xcite .
measurements down to liquid helium temperatures identified the transition to long - range ferromagnetic order @xcite , but an understanding of the magnetic interactions remained elusive until the 1970s , when x - ray @xcite and neutron @xcite diffraction data identified the crystal structure and the spin delocalization from high - spin fe(iii ) to low - spin fe(ii ) .
interest in these materials was renewed in the 1990s with the synthesis of several mixed - metal prussian blue analogs with higher magnetic ordering temperatures , along with the 1996 discovery of long - lived photoinduced magnetism in k@xmath7co@xmath8[fe(cn)@xmath2@xmath9h@xmath4o @xcite ..
Please generate the next two sentences of the article | a flurry of experimental and theoretical research has elucidated the fundamental nature of the light - induced effects in three - dimensional bulk materials @xcite , and recent efforts have been made to integrate the photoinduced magnetism into films @xcite and nanoparticles , which have technical and biophysical applications .
there have been several efforts to synthesize nanoparticles of prussian blue analogs @xcite , but only a few examples of photoinduced magnetism in these particles have been reported , including work that isolated k@xmath0co@xmath1[fe(cn)@xmath2@xmath3h@xmath4o particles with typical diameters of @xmath10 nm within a silica xerogel @xcite and other research producing 11 nm @xmath11 70 nm nanorods of mo(cn)@xmath12cu@xmath4 protected by polyvinylpyrrolidone ( pvp ) @xcite . in each case , although photoinduced magnetism was observed , the particles did not exhibit long - range order . |
9,829 | Suppose that you have an abstract for a scientific paper: a homology cylinder over a surface consists of a homology cobordism between two copies of the surface and markings of its boundary .
the set of isomorphism classes of homology cylinders over a fixed surface has a natural monoid structure and it is known that this monoid can be seen as an enlargement of the mapping class group of the surface .
we now focus on abelian quotients of this monoid .
we show that both the monoid of all homology cylinders and that of irreducible homology cylinders are not finitely generated and moreover they have big abelian quotients .
these properties contrast with the fact that the mapping class group is perfect in general . the proof is given by applying sutured floer homology theory to homologically fibered knots studied in a previous paper . .
And you have already written the first three sentences of the full article: let @xmath0 be a compact oriented connected surface of genus @xmath1 with one boundary component .
_ homology cylinders _ over @xmath0 , each of which consists of a homology cobordism @xmath2 between two copies of @xmath0 and markings of both sides of the boundary of @xmath2 , appeared in the context of the theory of finite type invariants for 3-manifolds ( see goussarov @xcite , habiro @xcite , garoufalidis - levine @xcite and levine @xcite ) , and play an important role in a systematic study of the set of 3-manifolds . in our previous paper @xcite , we observed their relationship to knot theory by introducing _
homologically fibered knots_. the set @xmath3 of isomorphism classes of homology cylinders over @xmath0 becomes a monoid by the natural stacking operation ..
Please generate the next two sentences of the article | it is known that the monoid @xmath3 contains the mapping class group @xmath4 of @xmath0 as the group of units ( see example [ ex : mgtocg ] ) . moreover ,
many techniques and invariants to study @xmath4 such as johnson homomorphisms and the magnus representation can be extended to @xmath3 ( see @xcite , @xcite ) . by using them |
9,830 | Suppose that you have an abstract for a scientific paper: we review some recent developments in the study of gibbs and non - gibbs properties of transformed @xmath0vector lattice and mean - field models under various transformations .
also , some new results for the loss and recovery of the gibbs property of planar rotor models during stochastic time evolution are presented .
* ams 2000 subject classification : * 82b20 , 82b26 , 60k35 . *
keywords : * gibbs measures , non - gibbsian measures , @xmath0vector lattice models , @xmath0vector mean - field models , transformed model , dobrushin uniqueness , cluster expansion , spin - flop transitions . .
And you have already written the first three sentences of the full article: in the recent decade and a half there has been a lot of activity on the topic of non - gibbsian measures .
most of the original studies were based on the question of whether renormalised hamiltonians exist as properly defined objects , @xcite , with an emphasis on discrete - spin models .
another issue , which also arose in physics but somewhat later @xcite , was the following question : apply a ( stochastic ) dynamics which converges to a system at a temperature @xmath1 to an initial state at temperature @xmath2 for a finite time ..
Please generate the next two sentences of the article | is the resulting measure in this transient non - equilibrium regime a gibbs measure ? could it be described in terms of an effective temperature ( hopefully between initial and final one ) ?
again the first results @xcite were for discrete spins . afterwards more general dynamics and |
9,831 | Suppose that you have an abstract for a scientific paper: we carry out systematic and high - resolution studies of dynamo action in a shell model for magnetohydrodynamic ( mhd ) turbulence over wide ranges of the magnetic prandtl number @xmath0 and the magnetic reynolds number @xmath1 .
our study suggests that it is natural to think of dynamo onset as a nonequilibrium , first - order phase transition between two different turbulent , but statistically steady , states .
the ratio of the magnetic and kinetic energies is a convenient order parameter for this transition . by using this order parameter
, we obtain the stability diagram ( or nonequilibrium phase diagram ) for dynamo formation in our mhd shell model in the @xmath2 plane .
the dynamo boundary , which separates dynamo and no - dynamo regions , appears to have a fractal character .
we obtain hysteretic behavior of the order parameter across this boundary and suggestions of nucleation - type phenomena .
# 1 # 2 # 3 ( # 1,#2)(0,0 ) ( 0,0)(#1,#2)#3 .
And you have already written the first three sentences of the full article: the elucidation of dynamo action is a problem of central importance in nonlinear dynamics because it has implications for a variety of physical systems
. dynamo instabilities , which amplify weak magnetic fields in a turbulent conducting fluid , are believed to be the principal mechanism for the generation of magnetic fields in celestial bodies and in the interstellar medium @xcite , and in liquid - metal systems @xcite studied in laboratories . in these situations
the kinematic viscosity @xmath3 and the magnetic diffusivity @xmath4 can differ by several orders of magnitude , so the magnetic prandtl number @xmath5 can either be very small or very large ; e.g. , @xmath6 at the base of the sun s convection zone , @xmath7 in the liquid - sodium system , and @xmath8 in the interstellar medium ..
Please generate the next two sentences of the article | this prandtl number is related to the reynolds number @xmath9 and the magnetic reynolds number @xmath10 that characterize the conducting fluid ; here @xmath11 and @xmath12 are typical length and velocity scales in the flow ; clearly @xmath13 .
two dissipative scales play an important role here ; they are the kolmogorov scale @xmath14 [ @xmath15 at the level of kolmogorov 1941 ( k41 ) phenomenology @xcite ] and the magnetic - resistive scale @xmath16 [ @xmath17 in k41 ] . for large prandtl numbers , |
9,832 | Suppose that you have an abstract for a scientific paper: we theoretically study transport properties of nanowires with the dresselhaus [ 110 ] spin - orbit coupling under the in - plane zeeman potential and the proximity - induced @xmath0-wave pair potential . in the topologically nontrivial phase
, the nanowire hosts the majorana fermions at its edges and the number of the majorana bound states is equal to the number propagating channels @xmath1 . when we attach a normal metal to the superconductor , such majorana bound states penetrate into the dirty normal segment and form the @xmath2 resonant transmission channels there .
we show that chiral symmetry of the electronic states protects the majorana bound states at the zero energy even in the presence of impurities . as a result
, we find that the zero - bias conductance of normal - nanowire / superconducting - nanowire junctions is quantized at @xmath3 independent of the random potentials . .
And you have already written the first three sentences of the full article: majorana fermion , particle which is own antiparticle , was originally predicted by ettore majorana in high energy physics@xcite .
recently , however , physics of majorana fermion has been a hot issue in condensed matter physics since the emergence of majorana fermion was pointed out at surfaces of topologically nontrivial superconductors@xcite . detecting a majorana fermion and controlling of majorana bound states(mbss ) have been a desired subject to realize the fault - tolerant topological quantum computation@xcite .
there are several suggested systems hosting mbss such as @xmath4 wave superconductors@xcite , topological insulator / superconductor heterostructures@xcite , semiconductor / superconductor junctions with strong spin - orbit interaction@xcite , helical superconductors@xcite , and superconducting topological insulators@xcite ..
Please generate the next two sentences of the article | the most practical system among them is a semiconductor nanowire fabricated on top of a superconductor because of its controllability for the emergence of mbs by changing the chemical potential in the nanowire and by applying the zeeman field onto it@xcite .
the coexistence of the rashba spin - orbit coupling and the zeeman potential enables a topologically nontrivial superconducting state in the nanowire in the presence of proximity induced pair potential there . |
9,833 | Suppose that you have an abstract for a scientific paper: we consider magnetic breakdown in twisted bilayer graphene where electrons may hop between semiclassical @xmath0-space trajectories in different layers .
these trajectories within a doubled brillouin zone constitute a network in which an @xmath1-matrix at each saddle point is used to model tunneling between different layers .
matching of the semiclassical wavefunctions throughout the network determines the energy spectrum .
semiclassical orbits with energies well below that of the saddle points are landau levels of the dirac points in each layer .
these continuously evolve into _ both _ electron - like and hole - like levels above the saddle point energy .
possible experimental signatures are discussed .
_ introduction _ the fundamental description of electron dynamics in a crystal and a uniform magnetic field involves orbital motion in a plane perpendicular to the field , along contours of constant energy @xcite as a function of crystal momentum * k*. this behavior can be significantly modified when tunneling from one trajectory to another becomes important , a phenomenon known as magnetic breakdown ( mb ) @xcite .
mb is important when the closest approach between @xmath0-space trajectories is on the order of the inverse of magnetic length , @xmath2}$ ] nm , where @xmath3 is the magnetic field in tesla .
mb sometimes leads to the formation of open orbits , with dramatic transport signatures @xcite .
mb effects in bulk metals can be challenging to observe because saddle points in a band structure , where mb initially sets in as the electron energy changes @xcite , are often quite far from the fermi energy .
recently , excellent candidates to observe mb phenomena have become available in the form of twisted graphene bilayers @xcite and graphene deposited on boron nitride substrates @xcite .
these two - dimensional systems can support large unit cells in real space ( `` moir patterns '' ) , and correspondingly small brillouin zones , for which critical points in the energy....
And you have already written the first three sentences of the full article: near @xmath23 , the electron wavefunction may be taken as proportional to @xmath141 , with small @xmath142 , independent of layer index .
only @xmath143 is relevant to the spectrum in this small range of momentum , and small terms of order @xmath0 can be treated perturbatively .
the form of @xmath143 is simplified by the transformation @xmath144 with @xmath145}$ ] , and the transformed @xmath143 now has only one nonzero matrix element . with the unitary transformation , ^+_1,2=-^-_1,2=w , where @xmath147 is positive and we assume @xmath148 , @xmath149 . defining ket vectors in terms of eigenstates of @xmath150 , @xmath151 and the constant @xmath152 ,.
Please generate the next two sentences of the article | the normalized eigenvectors are given by < ^+_1|h_1|^+_2>=-k_2 .
these matrix elements define an approximate projection of @xmath158 into the positive eigenvalue subspace of the @xmath26 hamiltonian in eq . |
9,834 | Suppose that you have an abstract for a scientific paper: we introduce the study of quantum protocols that probabilistically simulate quantum channels from a sender in the future to a receiver in the past .
the maximum probability of simulation is determined by causality and depends on the amount and type ( classical or quantum ) of information that the channel can transmit .
we illustrate this dependence in several examples , including ideal classical and quantum channels , measure - and - prepare channels , partial trace channels , and universal cloning channels . for the simulation of partial trace channels ,
we consider generalized teleportation protocols that take @xmath0 input copies of a pure state in the future and produce @xmath1 output copies of the same state in the past . in this case , we show that the maximum probability of successful teleportation increases with the number of input copies , a feature that was impossible in classical physics . in the limit of asymptotically large @xmath0
, the probability converges to the probability of simulation for an ideal classical channel .
similar results are found for universal cloning channels from @xmath0 copies to @xmath2 approximate copies , exploiting a time - reversal duality between universal cloning and partial trace . .
And you have already written the first three sentences of the full article: quantum theory is generally formulated relative to a given causal structure .
this is the case both in quantum field theory , where the spacetime metric is given from the beginning , and in the operational framework of quantum information , where protocols and computations consist in sequences of operations performed at different times .
relative to the given causal structure , quantum theory has to satisfy the _ causality principle _ @xcite , stating that the probability of a measurement outcome at a given time be independent of the choice of operations performed at later times ..
Please generate the next two sentences of the article | the causality principle forbids any form of signalling from the future to the past : a sender in the future can not deterministically transfer the state of his system to a receiver in the past .
however , it is easy to imagine situations where the state of a system is transferred from the future to the past _ with some probability _ , without leading to signalling |
9,835 | Suppose that you have an abstract for a scientific paper: we present a method for extracting the angular diameter distances , @xmath0 , and the expansion rates , @xmath1 , of the universe from the _ two - dimensional _ baryon acoustic oscillations ( bao ) in the galaxy power spectrum .
our method builds upon the existing algorithm called the `` fit - and - extract '' ( fitex ) method , which allows one to extract only @xmath2 from a spherically averaged one - dimensional power spectrum .
we develop the fitex-2d method , an extension of the fitex method , to include the two - dimensional information , which allows us to extract @xmath0 and @xmath1 simultaneously .
we test the fitex-2d method using the millennium simulation as well as simplified monte carlo simulations with a bigger volume .
the baos , however , contain only a limited amount of information .
we show that the full modeling , including the overall shape of the power spectrum , yields much better determinations of @xmath0 and @xmath1 , hence the dark energy equation of state parameters such as @xmath3 and @xmath4 , than the bao - only analysis by more than a factor of two , provided that non - linear effects are under control . .
And you have already written the first three sentences of the full article: dark energy , discovered via the observed luminosity distances out to high-@xmath5 type ia supernovae @xcite , is the most mysterious element in physics today ( see * ? ? ?
* for a recent review ) .
as dark energy primarily affects the expansion rate of the universe , one can gain information on the nature of dark energy by measuring the cosmological distances as well as the expansion rates of the universe accurately ..
Please generate the next two sentences of the article | while the cosmic microwave background ( cmb ) and the type ia supernovae can be used for measuring the angular diameter distance out to @xmath6 and the luminosity distances out to @xmath7 , respectively , the power spectrum of matter distribution in the universe can be used to measure the angular diameter distances _ as well as _ the expansion rates of the universe out to a wider range of redshifts . _
two _ length scales are encoded in the matter power spectrum , @xmath8 ( see , e.g. , * ? ? ? |
9,836 | Suppose that you have an abstract for a scientific paper: in this work we continue our study of fully packed loop ( fpl ) configurations in a triangle .
these are certain subgraphs on a triangular subset of @xmath0 , which first arose in the study of the usual fpl configurations on a square grid .
we show that , in a special case , the enumeration of these fpls in a triangle is given by littlewood
richardson coefficients .
the proof consists of a bijection with knutson tao puzzles . .
And you have already written the first three sentences of the full article: fully packed loop configurations ( fpls ) are configurations on a square grid to which a certain link pattern @xmath1 is attached ( see section [ sub : fpl ] for definitions ) . as was first shown in @xcite , fpl configurations in a triangle ( tfpls ) occur naturally when studying certain properties of the usual fpls .
the connection is explained in more detail in @xcite , where in several properties of tfpls are also shown .
the study of tfpls was initially motivated by the desire to obtain an expression for the number @xmath2 of fpls with link pattern @xmath1 ; also , as conjectured in @xcite and proved in @xcite , there exist linear relations between fpls whose coefficients are defined in terms of tfpls ..
Please generate the next two sentences of the article | these relations are in fact recurrence formulas allowing to compute all @xmath3 .
the famous razumov - stroganov correspondence @xcite gives rise to a different set of relations characterizing the @xmath2 ; they concern fpls all on the same grid size , while the recurrence formulas express fpls of size @xmath4 in terms of fpls of size @xmath5 . boundaries of tfpls can be encoded by dyck words @xmath6 , to which partitions @xmath7 are attached ; our main result ( theorem [ th : main ] ) is : _ if @xmath8 , then the number of tfpl configurations with boundary @xmath6 is given by the littlewood - richardson coefficient @xmath9 . |
9,837 | Suppose that you have an abstract for a scientific paper: the interface chemistry of silicon nanocrystals ( ncs ) embedded in amorphous oxide matrix is studied through molecular dynamics simulations with the chemical environment described by the reactive force field model .
our results indicate that the si nc - oxide interface is more involved than the previously proposed schemes which were based on solely simple bridge or double bonds .
we identify different types of three - coordinated oxygen complexes , previously not noted . the abundance and the charge distribution of each oxygen complex is determined as a function of the nc size as well as the transitions among them .
the oxidation at the surface of nc induces tensile strain to si - si bonds which become significant only around the interface , while the inner core remains unstrained . unlike many earlier reports on the interface structure
, we do not observe any double bonds .
furthermore , our simulations and analysis reveal that the interface bond topology evolves among different oxygen bridges through these three - coordinated oxygen complexes . .
And you have already written the first three sentences of the full article: after a long arduous effort , photoluminescence from silicon has been achieved from its nanocrystalline form @xcite .
a critical debate , however , continues over the nature of the interface chemistry of silicon nanocrystals ( si - ncs ) embedded in amorphous silica which has direct implications on the optical activity of the interface @xcite .
_ reported that the oxidation of porous silicon quantum dots results in a red shift in the photoluminescence ( pl ) spectra which indicates the importance of oxygen - related interface bond toplogy @xcite ..
Please generate the next two sentences of the article | along this line , puzder and co - workers compared pl calculations of nanoclusters with different passivants and surface configurations and proposed the main reason for the red shift to be double si = o bonds @xcite . countering this , luppi _
et al . _ reported excitonic luminescence features caused by si - o - si bridge bonds at the surface of silicon nanoclusters @xcite . |
9,838 | Suppose that you have an abstract for a scientific paper: we theoretically study the transport properties of both monolayer and bilayer graphene in the presence of electron - hole puddles induced by charged impurities which are invariably present in the graphene environment .
we calculate the graphene conductivity by taking into account the non - mean - field two - component nature of transport in the highly inhomogeneous density and potential landscape , where activated transport across the potential fluctuations in the puddle regimes coexists with regular metallic diffusive transport .
the existence of puddles allows the local activation at low carrier densities , giving rise to an insulating temperature dependence in the conductivity of both monolayer and bilayer graphene systems .
we also critically study the qualitative similarity and the quantitative difference between monolayer and bilayer graphene transport in the presence of puddles .
our theoretical calculation explains the non - monotonic feature of the temperature dependent transport , which is experimentally generically observed in low mobility graphene samples .
we establish the 2-component nature ( i.e. , both activated and diffusive ) of graphene transport arising from the existence of potential fluctuation induced inhomogeneous density puddles .
the temperature dependence of the graphene conductivity arises from many competing mechanisms , even without considering any phonon effects , such as thermal excitation of carriers from the valence band to the conduction band , temperature dependent screening , thermal activation across the potential fluctuations associated with the electron - hole puddles induced by the random charged impurities in the environment , leading to very complex temperature dependence which depends both on the carrier density and the temperature range of interest . .
And you have already written the first three sentences of the full article: graphene , as a novel gapless two dimensional ( 2d ) chiral electron - hole system , has attracted great interest in recent years , both experimentally and theoretically@xcite .
its transport properties have been at the center of key fundamental and technological efforts with vast potential for applications in future nanotechnology@xcite . for monolayer graphene ( mlg ) ,
the fundamental interest arises from its unique linear chiral dirac carrier dispersion with a zero energy gap between conduction and valence band@xcite ..
Please generate the next two sentences of the article | the bilayer graphene ( blg ) is also intriguing as its physical properties lie between mlg and 2d semiconductor - based electron gas ( 2deg ) systems which are gapped and non - chiral with a quadratic band dispersion .
much of the early work on graphene transport focused on the density - dependent ( i.e. , gate voltage tuned)@xcite and temperature - dependent @xcite conductivity in homogeneous mlg and blg systems . |
9,839 | Suppose that you have an abstract for a scientific paper: there are six main things which any non - baryonic dark matter theory should endeavour to explain : ( 1 ) the basic dark matter particle properties [ mass , stability , darkness ] ; ( 2 ) the similarity in cosmic abundance between ordinary and non - baryonic dark matter , @xmath0 ; ( 3 ) large scale structure formation ; ( 4 ) microlensing ( macho ) events ; ( 5 ) asymptotically flat rotation curves in spiral galaxies ; ( 6 ) the impressive dama / nai annual modulation signal .
only mirror matter - type dark matter is capable of explaining all six of these desirable features .
the purpose of this article is to provide an up - to - date and pedagogical review of this dark matter candidate . .
And you have already written the first three sentences of the full article: there is a very strong scientific case that most of the matter in the universe consists of non - baryonic stable particles .
since the standard model of particle physics does not contain any heavy stable non - baryonic particles new particle physics is required .
but what is this new physics.
Please generate the next two sentences of the article | ? it is widely assumed that the particles comprising non - baryonic dark matter are weakly interacting in the sense that they interact with ordinary matter via exchange of w , z gauge bosons , higgs bosons or more exotic heavy particles . from collider bounds
( e.g. lack of new particles in decays of the w and z gauge bosons ) , the masses of any new weakly interacting particles should be ( typically ) greater than about 30 - 45 gev , unless indicated otherwise . ] depending on the model . |
9,840 | Suppose that you have an abstract for a scientific paper: in economics duopoly is a market dominated by two firms large enough to influence the market price .
stackelberg presented a dynamic form of duopoly that is also called ` leader - follower ' model .
we give a quantum perspective on stackelberg duopoly that gives a backwards - induction outcome same as the nash equilibrium in static form of duopoly also known as cournot s duopoly .
we find two qubit quantum pure states required for this purpose .
pacs : 03.67.lx 02.50.le 87.23.kg keywords : quantum game theory , nash equilibrium , backwards - induction outcome , stackelberg and cournot models of duopoly game . .
And you have already written the first three sentences of the full article: quantum game theory started from a seminal paper by meyer @xcite .
later eisert et .
@xcite studied the important bimatrix game of prisoner s dilemma ( pd ) while focussing on the concept of nash equilibrium ( ne ) from noncooperative game theory ..
Please generate the next two sentences of the article | this concept attracted much attention in other recent works in quantum game theory @xcite .
in fact cournot ( 1838 ) @xcite anticipated nash s definition of equilibrium by over a century but only in the context of a particular model of duopoly . in economics , |
9,841 | Suppose that you have an abstract for a scientific paper: a new type of peculiarity a splitting or asymmetry of strong absorption lines , is found in the optical spectra of selected post agb stars with c rich circumstellar envelopes .
the effect is maximal in baii lines whose profile is split into two three components .
the particular components of the split absorption lines are shown to be formed in a structured circumstellar envelope , suggesting an efficient dredge up of the heavy metals produced during the preceding evolution of this star into the envelope .
we suspect that the splitting ( or asymmetry ) of the profiles of strongest absorptions with low excitation potential of the low level can be associated with the kinematic and chemical properties of the circumstellar environment and with type of its morphology . .
And you have already written the first three sentences of the full article: now generally accepted that about half of abundances of chemical elements heavier than iron are produced by slow neutron captures ( s process ) in the deep layers of asymptotic giant branch ( agb ) stars .
mixing brings freshly synthesized heavy elements to the stellar surface ( the third dredge - up process ) and then stellar wind carries them away in the stellar enviroments .
this is a simplified description of the processes , the sequence of which enriches both circumstellar and interstellar medium with heavy metals . for more detail.
Please generate the next two sentences of the article | see , e.g. , @xcite and references there .
agb stars are therefore the principal suppliers of heavy metals and important suppliers of carbon and nitrogen to the interstellar medium , thereby participating in the chemical evolution of galaxies . in this article , we shall focus on the first observational evidences on the presence of circumstellar spectral features of heavy metals in the optical spectra of nearest descendants of agb - stars protoplanetary nebulae ( ppne ) . |
9,842 | Suppose that you have an abstract for a scientific paper: we propose a method to study the epoch of reionization based on the possible observation of 2p2s fine structure lines from the neutral hydrogen outside the cosmological h ii regions enveloping qsos and other ionizing sources in the reionization era .
we show that for parameters typical of luminous sources observed at @xmath0 the strength of this signal , which is proportional to the h i fraction , has a brightness temperature @xmath1 for a fully neutral medium .
the fine structure line from this redshift is observable at @xmath2 and we discuss prospects for the detection with several operational and future radio telescopes .
we also compute the characteristics of this signal from the epoch of recombination : the peak brightness is expected to be @xmath3 ; this signal appears in the frequency range 5 - 10 mhz .
the signal from the recombination era is nearly impossible to detect owing to the extreme brightness of the galactic emission at these frequencies . .
And you have already written the first three sentences of the full article: even though the existence of hydrogen fine structure lines and their explanation using dirac s atomic theory has been known for close to a century , a hydrogen fine structure line has never been detected from an astrophysical object .
an interesting hydrogen fine structure line is the @xmath4 transition .
the main difficulty in detecting this line is that the line strength is proportional to the population of either the @xmath5 or @xmath6 states which , being excited states , are not so readily populated in most astrophysical circumstances ..
Please generate the next two sentences of the article | moreover , the line width of the excited @xmath5 state , which is determined by its decay time , is large ( 99.8 mhz ) , making the detection of the fine structure line a difficult observation .
one astrophysical setting where the feasibility of detecting such a line has been studied is the interstellar h ii regions ( see , _ e.g. _ , dennison , turner , & minter 2005 and references therein ; ershov 1987 ) ; in h ii regions , the excited levels are populated by recombination . |
9,843 | Suppose that you have an abstract for a scientific paper: gain in current - driven semiconductor heterostructure devices is calculated within the theory of nonequilibrium green functions . in order to treat the nonequilibrium distribution self - consistently the full two - time structure of the theory
is employed without relying on any sort of kadanoff - baym ansatz .
the results are independent of the choice of the electromagnetic field if the variation of the self - energy is taken into account .
excellent quantitative agreement is obtained with the experimental gain spectrum of a quantum cascade laser .
calculations for semiconductor superlattices show that the simple 2-time miniband transport model gives reliable results for large miniband widths at room temperature . .
And you have already written the first three sentences of the full article: the prospect of a semiconductor laser in the infrared and thz region has been one of the key reasons for the development and study of semiconductor heterostructure elements , since the first proposal of semiconductor superlattices in 1970 @xcite .
a possible gain mechanism may be based on two different ideas : ( i ) at certain electrical fields resonant tunneling between different subbands can lead to population inversion associated with gain at the transition energy @xcite .
this idea was realized in the quantum cascade laser @xcite , which has become an important device in the infrared region ..
Please generate the next two sentences of the article | lasing in the thz region has been demonstrated very recently as well @xcite .
for further details , see the review @xcite . |
9,844 | Suppose that you have an abstract for a scientific paper: second fourier harmonics of jet quenching have been thoroughly explored in the literature and shown to be sensitive to the underlying jet path - length dependence of energy loss and the differences between the mean eccentricity predicted by glauber and cgc / kln models of initial conditions .
we compute the jet path - length dependence of energy - loss for higher azimuthal harmonics of jet - fragments in a generalized model of energy - loss for rhic energies and find , however , that even the high-@xmath0 second moment is most sensitive to the poorly known early - time evolution during the first fm / c .
moreover , we demonstrate that higher - jet harmonics are remarkably insensitive to the initial conditions , while the different @xmath1 vs. @xmath2 correlations between the moments of monojet and dijet nuclear modifications factors remain a most sensitive probe to differentiate between glauber and cgc / kln initial state sqgp geometries . .
And you have already written the first three sentences of the full article: heavy - ion collisions at the relativistc heavy ion collider ( rhic ) indicate the production of an opaque ( i.e. strongly jet - suppressing ) @xcite , strongly - coupled , fast - thermalizing medium that possibly needs to be described using methods derived from ads / cft string theory @xcite .
however , so far neither the initial conditions of the collisions nor the microscopic dynamics of the jet - energy loss are conclusively understood .
two models are commonly used to characterize the initial conditions . the glauber model @xcite , describing incoherent superpositions of proton - proton collisions , and the `` color glass condensate '' ( cgc ) @xcite , given e.g. by the kln model @xcite , where saturation effects are taken into account ..
Please generate the next two sentences of the article | they differ by their initial temperature gradients , their initial high-@xmath0 parton distribution , and the distance travelled by each parton , leading to a different opacity estimate .
in addition , both models exhibit large event - by - event fluctuations @xcite . |
9,845 | Suppose that you have an abstract for a scientific paper: this paper gives a personal impression of the conference `` asymmetrical pne ii : from origins to microstructures '' , flags some of the highlights , gathers together some facts and terminology , and indicates some promising future lines of work in this field .
# 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: these conference proceedings are the condensed result of the 2nd meeting on asymmetrical pne , held at mit during august of 1999 .
being the last such meeting of this millennium , and a successor of the successful 1st asymmetrical meeting held at oranim in israel during august 1994 , and published as anns.isr.phys.soc.,11 in 1995 , it was especially good to see that the subject has made significant progress over the last lustrum .
the main impact , as you can see immediately by just a quick skim through this volume , has come from the imaging done by the hubble space telescope ..
Please generate the next two sentences of the article | the wealth of complex detail revealed by these unprecedented images has left the theorists reeling , the observers gasping , and both groups with plenty ground based work ahead of them .
a special highlight of the meeting was the free hand out to participants of a cd with superb wfpc2 images by hajian & terzian ! |
9,846 | Suppose that you have an abstract for a scientific paper: we introduce two new exactly solvable ( stochastic ) interacting particle systems which are discrete time versions of @xmath0-tasep .
we call these geometric and bernoulli discrete time @xmath0-tasep .
we obtain concise formulas for expectations of a large enough class of observables of the systems to completely characterize their fixed time distributions when started from step initial condition .
we then extract fredholm determinant formulas for the marginal distribution of the location of any given particle
. underlying this work is the fact that these expectations solve closed systems of difference equations which can be rewritten as free evolution equations with @xmath1 two - body boundary conditions discrete @xmath0-deformed versions of the quantum delta bose gas .
these can be solved via a nested contour integral ansatz .
the same solutions also arise in the study of macdonald processes , and we show how the systems of equations our expectations solve are equivalent to certain commutation relations involving the macdonald first difference operator .
[ section ] [ section ] [ theorem]conjecture [ theorem]lemma [ theorem]proposition [ theorem]corollary [ theorem]claim [ theorem]critical point derivation [ theorem]experimental result # 1 # 1#1 # 1 [ theorem]remark [ theorem]example [ theorem]definition [ theorem]definitions .
And you have already written the first three sentences of the full article: the purpose of this paper is to introduce and analyze two exactly solvable discrete time versions of @xmath0-tasep . before introducing them we recall the continuous time poisson @xmath0-tasep which was previously studied in @xcite .
let us fix some notation used throughout . for @xmath2
we denote the state of @xmath0-tasep with @xmath3 particles as @xmath4 , where we have fixed a virtual particle at infinity by setting @xmath5 ..
Please generate the next two sentences of the article | the gap between particle @xmath6 and @xmath7 is denoted @xmath8 .
we define and provide some background for the continuous time poisson @xmath0-tasep . |
9,847 | Suppose that you have an abstract for a scientific paper: we review the appearance of slater - pauling rules in half - metallic magnets .
these rules have been derived using ab - initio electronic structure calculations and directly connect the electronic properties ( existence of minority - spin energy gap ) to the magnetic properties ( total spin magnetic moment ) in these compounds .
their exact formulation depends on the half - metallic family under study and they can be easily derived if the hybridization of the orbitals at various sites is taken into account .
+ + * keywords : * electronic structure calculations , magnetism , half - metals , slater - pauling + + * corresponding author :* _ postal address : department of materials science , university of patras , gr-26504 patra , tel.:+30 - 2610 - 969925 , fax:+30 - 2610 - 969925 , e - mail address : [email protected]_ .
And you have already written the first three sentences of the full article: the developments in electronics , combining the magnetic and semiconducting materials ( so - called magnetoelectronis or spintronics ) @xcite , have brought half - metallic magnets , initially predicted by de groot and collaborators in 1983 @xcite , to the center of scientific research . in these materials
the two spin bands show a completely different behavior . while the spin - up electronic band structure is metallic , in the spin - down band the fermi level falls within an energy gap as in semiconductors @xcite .
such half - metallic compounds exhibit , ideally , a 100% spin polarization at the fermi level and therefore they should have a fully spin - polarized current and be ideal spin injectors into a semiconductor , thus maximizing the efficiency of spintronic devices @xcite ..
Please generate the next two sentences of the article | the interest on half - metallic magnets has been mainly focused on the heusler compounds .
the are two distinct families of heuslers . |
9,848 | Suppose that you have an abstract for a scientific paper: the effect of electron - optical phonon interaction on the hydrogenic impurity binding energy in a cylindrical quantum wire is studied . by using landau and
pekar variational method , the hamiltonian is separated into two parts which contain phonon variable and electron variable respectively . a perturbative - variational technique is then employed to construct the trial wavefunction for the electron part .
the effect of confined electron - optical phonon interaction on the binding energies of the ground state and an excited state are calculated as a function of wire radius .
both the electron - bulk optical phonon and electron - surface optical phonon coupling are considered .
it is found that the energy corrections of the polaron effects on the impurity binding energies increase rapidliy as the wire radius is shrunk , and the bulk type optical phonon plays the dominant role for the polaron effects .
pacs : 71.38+i;73.20.dx;63.20.kr .
And you have already written the first three sentences of the full article: during the past decades the development of the epitaxial crystal growth techniques such as molecular beam epitaxy and metal - organic chemical vapor deposition has made the growth of the quasi - two - dimensional ( quantum well ) or quasi - one - dimensional ( quantum wire)@xcite systems with controllable well thickness or wire radius became possible .
these quantum structures have been applied to many semiconductor devices , such as high - electron - mobility transistors .
recent progresses in growth and fabrication techniques have been able to fabricate the quantum wires with radii less than 100 @xmath0 ..
Please generate the next two sentences of the article | theoretically , the electronic properties of a hydrogenic impurity in the quantum well5,6,7,8 and the quantum wire @xcite have been studied by many authors .
the impurity binding energies of a quantum wire with infinite or finite potential barrier @xcite and with different shapes of the cross - section@xcite have been discussed . |
9,849 | Suppose that you have an abstract for a scientific paper: in reply to ref . @xcite we demonstrate why the arguments made therein do not address the criticism exposed in ref .
@xcite on the fundamental shortcomings of the bayesian approach when it comes to the extraction of parameters of nature from experimental data . as for the isospin analysis and the ckm angle
@xmath0 it is shown that the use of uniform priors for the observed quantities in the explicit solution parametrization is equivalent to a frequentist construction resulting from a change of variables , and thus relies neither on prior pdfs nor on bayes theorem .
this procedure provides in this particular case results that are similar to the confidence level approach , but the treatment of mirror solutions remains incorrect and it is far from being general . in a second part it is shown that important differences subsist between the bayesian and frequentist approaches , when following the proposal of ref .
@xcite and inserting additional information on the hadronic amplitudes beyond isospin invariance . in particular the frequentist
result preserves the exact degeneracy that is expected from the remaining symmetries of the problem while the bayesian procedure does not .
moreover , in the bayesian approach reducing inference to the 68% or 95% credible interval is a misconception of the meaning of the posterior pdf , which in turn implies that the significant dependence of the latter to the chosen parametrization can not be viewed as a minor effect , contrary to the claim in ref . @xcite . .
And you have already written the first three sentences of the full article: in ref . @xcite we have shown through the example of the extraction of the cabibbo - kobayashi - maskawa ( ckm ) angle @xmath0 from @xmath1 decays that the bayesian treatment as done , e.g. , by the utfit collaboration @xcite , suffers from major difficulties .
the problems we have found are related to the presence of unknown free parameters which should actually be constrained by the data .
we have shown that the results of the bayesian analysis depend on the priors and the chosen parameterization in an uncontrollable manner , and may even diverge in some cases ..
Please generate the next two sentences of the article | furthermore we have demonstrated that the priors can not always be specified in a consistent way with respect to the symmetries of the problem , which results in the present example in an incorrect description of the @xmath2 limit .
the authors of ref . |
9,850 | Suppose that you have an abstract for a scientific paper: in this article two - loop qed corrections to the muon decay and corrections of order @xmath0 to the semileptonic decay of the bottom quark are considered .
we compute the imaginary part of the four - loop diagrams contributing to the corresponding fermion propagator in the limit of small external momentum .
the on - shell condition is obtained with the help of a conformal mapping and pad approximation . via this method
we confirm the existing results by an independent calculation . .
And you have already written the first three sentences of the full article: the fermi coupling constant , @xmath1 , constitutes together with the electromagnetic coupling constant and the mass of the @xmath2 boson the most precise input parameters of the standard model of elementary particle physics .
@xmath1 is defined through the muon lifetime , and the decay of the muon , as a purely leptonic process , is rather clean both experimentally and theoretically .
the one - loop corrections of order @xmath3 were computed more than 40 years ago @xcite whereas only recently the two - loop corrections of order @xmath4 have been evaluated @xcite ..
Please generate the next two sentences of the article | the large gap in time shows that this calculation is highly non - trivial .
the inclusion of the two - loop terms removed the relative theoretical error of @xmath5 which was an estimate on the size of the missing corrections . |
9,851 | Suppose that you have an abstract for a scientific paper: we present 109115ghz ( 3 mm ) wide - field spectral line observations of @xmath0co , @xmath1co and c@xmath2o molecular emission and 5.5 and 8.8ghz ( 6 and 3 cm ) radio continuum emission towards the high - mass star forming complex known as g305 .
the morphology of g305 is dominated by a large evacuated cavity at the centre of the complex driven by clusters of o stars surrounded by molecular gas .
our goals are to determine the physical properties of the molecular environment and reveal the relationship between the molecular and ionised gas and star formation in g305 .
this is in an effort to characterise the star - forming environment and constrain the star formation history in an attempt to evaluate the impact of high - mass stars on the evolution of the g305 complex .
analysis of co emission in g305 reveals 156 molecular clumps with the following physical characteristics ; excitation temperatures ranging from 725k , optical depths of 0.20.9 , h@xmath3 column densities of @xmath4@xmath5@xmath6 , clump masses ranging from @xmath7@xmath8m@xmath9 and a total molecular mass of @xmath10m@xmath9 .
the 5.5 and 8.8ghz radio continuum emission reveals an extended low surface brightness ionised environment within which we identify 15 large - scale features with a further eight smaller sources projected within these features . by comparing to mid infrared emission and archival data , we identify nine hii regions , seven compact hii regions , one region , four extended regions .
the total integrated flux of the radio continuum emission at 5.5ghz is @xmath11jy corresponding to a lyman continuum output of @xmath12photonss@xmath13 .
we compare the ionised and molecular environment with optically identified high - mass stars and ongoing star formation , identified from the literature .
analysis of this dataset reveals a star formation rate of 0.0080.016m@xmath9yr@xmath13 and efficiency of 712% , allows us to probe the star formation history of the region and discuss the impact of high - mass stars....
And you have already written the first three sentences of the full article: high - mass stars ( m@xmath14m@xmath9 ) are predominantly observed in young ( @xmath15myr ) , massive clusters ( m@xmath16m@xmath9 ) located within giant molecular clouds ( gmcs ) . despite their rarity and short life times , high - mass stars are responsible for injecting a significant amount of energy into the interstellar medium ( ism ) by means of stellar winds , ionising radiation and supernovae .
the impact of such feedback mechanisms from high - mass stars on the ism and star formation is still a topic of debate but is thought to play an important role in driving the evolution of gmcs .
feedback can be both constructive and destructive by sweeping up and clearing out parsec - scale cavities ( or bubbles ) in the ism @xcite resulting in dense gas shells or destroying and dispersing the molecular environment ..
Please generate the next two sentences of the article | this means that feedback from high - mass stars should have the potential to both inhibit or enhance subsequent star formation and profoundly influence the star formation history ( sfh ) of gmcs @xcite .
the g305 gmc complex is located within the scutum - crux arm of the milky way at @xmath17 , @xmath18 at a distance of @xmath19kpc and is one of the most massive and luminous star - forming regions in the galaxy @xcite . |
9,852 | Suppose that you have an abstract for a scientific paper: the large magellanic cloud ( lmc ) has a unique cluster formation history in that nearly all of its globular clusters were formed either @xmath0 13 gyr ago or less than @xmath0 3 gyr ago .
it is not clear what physical mechanism is responsible for the most recent cluster formation episode and thus the mysterious age gap between the lmc clusters .
we first present results of gas dynamical n - body simulations of the evolution of the lmc in the context of its galactic orbit and interactions with the smc , paying special attention to the effect of tidal forces .
we find that the first close encounter between the lmc and the small magellanic cloud ( smc ) about 4 gyr ago was the beginning of a period of strong tidal interaction which likely induced dramatic gas cloud collisions , leading to an enhancement of the formation of globular clusters which has been sustained by strong tidal interactions to the present day .
the tidal interaction results in the formation of a barred , elliptical , thick disk in the lmc .
the model also predicts the presence of a large , diffuse stellar stream circling the galaxy , which originated from the lmc . .
And you have already written the first three sentences of the full article: tidal interactions between galaxies are suggested , both from observations and theory , to dramatically change the formation rates of field stars and globular clusters due to the tidal compression of gas clouds and their efficient conversion into stars ( kennicutt 1998 ; ashman & zepf 1992 ; noguchi & ishibashi 1986 ; bekki & couch 2001 ; bekki et al .
the large and small magellanic clouds ( lmc and smc ) , which are the nearest pair of interacting galaxies in our vicinity , have served as unique laboratories for studying the interplay between galactic dynamical evolution and star formation activity in galaxies ( westerlund 1997 ; van den bergh 2000 ) .
a major curiosity in this context is that globular cluster formation which is considered to be a special mode of star formation ( harris & pudritz 1994 ; elmegreen & efremov 1997 ) is observed to be ongoing in the clouds but not in the galaxy ..
Please generate the next two sentences of the article | clearly the physical conditions required for cluster formation currently exist in the clouds but not in the galaxy ( westerlund 1997 ; van den bergh 2000 ) .
moreover , the age distribution of the lmc clusters shows a gap extending from 3 to 13 gyr with only one cluster in this age range suggesting a second epoch of cluster formation started abruptly in the lmc about 3 gyr ago ( e.g. , da costa 1991 ; geisler et al . |
9,853 | Suppose that you have an abstract for a scientific paper: the circumstellar ( cs ) environment is key to understanding progenitors of type ia supernovae ( sne ia ) , as well as the origin of a peculiar extinction property toward sne ia for cosmological application . it has been suggested that multiple _
scatterings _ of sn photons by cs dust may explain the non - standard reddening law . in this paper , we examine the effect of _ re - emission _ of sn photons by cs dust in the infrared ( ir ) wavelength regime .
this effect allows the observed ir light curves to be used as a constraint on the position / size and the amount of cs dust .
the method was applied to observed near - infrared ( nir ) sn ia samples ; meaningful upper limits on the cs dust mass were derived even under conservative assumptions .
we thereby clarify a difficulty associated with the cs dust scattering model as a general explanation for the peculiar reddening law , while it may still apply to a sub - sample of highly reddened sne ia .
for sne ia in general , the environment at the interstellar scale appears to be responsible for the non - standard extinction law .
furthermore , deeper limits can be obtained using the standard nature of sn ia nir light curves . in this application , an upper limit of @xmath0 yr@xmath1 ( for the wind velocity of @xmath2 km s@xmath1 )
is obtained for a mass loss rate from a progenitor up to @xmath3 pc , and @xmath4 yr@xmath1 up to @xmath5 pc .
[ firstpage ] circumstellar matter stars : mass - loss dust , extinction supernovae : general . .
And you have already written the first three sentences of the full article: type ia supernovae ( sne ia ) are mature standardised candles .
intrinsic dispersion of the peak absolute magnitude can be minimised to the level of @xmath6 magnitude or even smaller , and can be accurately used as a cosmological distance indicator @xcite .
however , this standardisation generally requires a non - standard extinction law , i.e. , @xmath7 , as opposed to the typical galactic value of @xmath8 ( e.g. , * ? ? ?.
Please generate the next two sentences of the article | this indicates that the properties of dust in sn ia host galaxies may be systematically different from those in our galaxy ( e.g. , * ? ? ?
alternatively , it has been suggested that multiple _ |
9,854 | Suppose that you have an abstract for a scientific paper: two charge- and current neutral plasma beams are modelled with a one - dimensional pic simulation .
the beams are uniform and unbounded .
the relative speed between both beams is 0.4c .
one beam is composed of electrons and protons and one out of protons and negatively charged oxygen ( dust ) . all species have the temperature 9 kev .
a buneman instability develops between the electrons of the first beam and the protons of the second beam .
the wave traps the electrons , which form plasmons .
the plasmons couple energy into the ion acoustic waves , which trap the protons of the second beam .
a proton phase space hole grows , which develops through its interaction with the oxygen and the heated electrons into a rarefaction pulse .
this pulse drives a strong ion acoustic double layer , which accelerates a beam of electrons to about 50 mev , which is comparable to the proton kinetic energy .
the proton distribution eventually evolves into an electrostatic shock .
beams of charged particles moving at such speeds may occur in the foreshock of supernova remnant shocks .
this double layer is thus potentially relevant for the electron acceleration ( injection ) into the diffusive shock acceleration by supernova remnants shocks . .
And you have already written the first three sentences of the full article: the blast shell of a supernova remnant ( snr ) can accelerate charged particles to cosmic ray energies through diffusive shock acceleration by the snr shocks @xcite . particles are scattered upstream and downstream of a shock and some particles cross the shock repeatedly , gaining energy each time @xcite .
diffusive shock acceleration requires a seed population of particles with energies well in excess of the thermal ones , since only such particles can cross the shock repeatedly and be scattered efficiently by the magnetohydrodynamic waves on either side of the shock .
the presence of shock - accelerated electrons is evidenced by the radio emissions of snrs ..
Please generate the next two sentences of the article | it is not clear yet how the electrons can reach the energy threshold for diffusive shock acceleration ; that requires that their kinetic energies are comparable to those of the ions .
some electrons must be accelerated locally , that is close to the snr shock or close to one of its precursors @xcite . |
9,855 | Suppose that you have an abstract for a scientific paper: analyzing the spectra from wolf - rayet stars requires adequate non - lte modeling of their expanding atmosphere .
the numerical schemes for solving the radiative transfer in the co - moving frame of reference have been developed by mihalas and co - workers 30 years ago .
the most elaborate codes can cope today with many hundred explicit non - lte levels or super - levels and account for metal - line blanketing .
the limited agreement with observed spectra indicates that the model simplifications are still severe .
one approximation that has to be blamed is homogeneity .
stellar - wind clumping on small scales was easily implemented , while `` macro - clumping '' is still a big challenge .
first studies showed that macro - clumping can reduce the strength of predicted p - cygni line profiles in o - star spectra , and largely affects the x - ray line spectra from stellar winds .
the classical model for radiation - driven winds by castor , abbot and klein fails to explain the very dense winds from wolf - rayet stars .
only when we solved the detailed non - lte radiative transfer consistently with the hydrodynamic equations , mass - loss rates above the single - scattering limit have been obtained .
address = universitt potsdam , germany address = universitt potsdam , germany , , altaddress = armagh observatory , northern ireland address = universitt potsdam , germany address = universitt potsdam , germany .
And you have already written the first three sentences of the full article: dimitri mihalas and co - workers developed the formalism and the numerical algorithms to model the atmospheres of hot stars in non - lte .
after having accomplished this task for the static , plane - parallel case , the problem of spherically expanding atmospheres was attacked in a series of seminal papers by mihalas , kunasz , and hummer in the years 1975/76 .
one important step was to realize that the radiative transfer in highly supersonic flows , where the doppler shifts are much larger than the width of the line absorption profile , are treated most conveniently in the co - moving frame of reference ( cmf ) ..
Please generate the next two sentences of the article | for the equations of statistical equilibrium the `` radiative transition rates '' are required , and these have to be evaluated with the ( angle - averaged ) radiation intensity in the cmf as it is `` seen '' by the matter . as a drawback , the equation of radiative transfer becomes a _ partial _ differential equation in the cmf : because the frequency @xmath0 is measured with respect to the co - moving frame , a photon is changing its frequency when propagating through the differentially moving medium . for a ray with coordinate @xmath1 , a velocity @xmath2 in radial direction , and angle @xmath3 between the radial direction and the ray ,
the cmf transfer is @xmath4 in spherically extended atmospheres , the radiation field becomes very anisotropic , and hence many rays of different angle ( or , impact parameter ) are needed for an accurate numerical representation . |
9,856 | Suppose that you have an abstract for a scientific paper: in the study of trapped two - component bose gases , a widely used dynamical protocol is to start from the ground state of a one - component condensate and then switch half the atoms into another hyperfine state . the slightly different intra - component and inter - component interactions can then lead to highly nontrivial dynamics .
we study and classify the possible subsequent dynamics , over a wide variety of parameters spanned by the trap strength and by the inter- to intra - component interaction ratio . a stability analysis suited to the trapped situation
provides us with a framework to explain the various types of dynamics in different regimes . .
And you have already written the first three sentences of the full article: two - component bose - einstein condensates ( becs ) are increasingly appreciated as a rich and versatile source of intricate non - equilibrium pattern dynamics phenomena .
in addition to experimental observations @xcite , pattern dynamics in two - component becs has attracted significant theoretical interest ( see , e.g. , @xcite and citations in @xcite ) . in a number of two - component bec experiments
reported over more than a decade , a standard technique has been to start from the equilibrium state of a single - component bec , e.g. , populating a single hyperfine state of @xmath0rb , and then using a @xmath1 pulse to switch half the atoms to a different hyperfine state @xcite ..
Please generate the next two sentences of the article | this results in a binary condensate where the two intra - species interactions ( @xmath2 and @xmath3 ) and one inter - species interaction ( @xmath4 ) are all slightly different from each other , but the starting state is the ground state determined by @xmath2 alone .
since it has been realized several times in several different laboratory setups , this is a paradigm non - equilibrium initial state for binary condensate dynamics . |
9,857 | Suppose that you have an abstract for a scientific paper: we study the effects of rotation on the torsional modes of oscillating relativistic stars with a solid crust .
earlier works in newtonian theory provided estimates of the rotational corrections for the torsional modes and suggested that they should become cfs unstable , even for quite low rotation rates . in this work ,
we study the effect of rotation in the context of general relativity using elasticity theory and in the slow - rotation approximation .
we find that the newtonian picture does not change considerably .
the inclusion of relativistic effects leads only to quantitative corrections .
the degeneracy of modes for different values of @xmath0 is removed , and modes with @xmath1 are shifted towards zero frequencies and become secularly unstable at stellar rotational frequencies @xmath2 20 - 30 hz .
[ firstpage ] relativity methods : numerical stars : neutron stars : oscillations stars : rotation .
And you have already written the first three sentences of the full article: neutron stars are objects of extremely rich internal structure .
although their interior structure is still very uncertain , it seems that observations and theoretical studies of neutron stars are quite in agreement concerning the structure of their exterior parts .
more specifically , there is agreement that neutron stars , 1 - 2 minutes after their formation , are cold enough to solidify their exteriors and form a crystal crust thanks to coulomb forces between the various atomic nuclei ..
Please generate the next two sentences of the article | the crust is covered by a very thin fluid ocean , while the interior is formed by a super - fluid mantle ( up to 5 km in size ) .
the composition of the core is highly uncertain . |
9,858 | Suppose that you have an abstract for a scientific paper: i consider compton scattering off the nucleon in the presence of @xmath0 violation .
i construct the compton tensor which possesses these features and consider low energy expansion ( lex ) of the corresponding amplitudes .
it allows to separate out the born contribution which only depends on the static properties of the nucleon , such as the electric charge , the mass , the magnetic moment , and the electric dipole moment ( edm ) .
i introduce new structure constants , the @xmath0-odd nucleon polarizabilities which parametrize the unknown non - born part .
these constants describe the response of the @xmath0-violating content of the nucleon to the external quasistatic electromagnetic field . as an estimate
, i provide a hbchpt calculation for these new polarizabilities and discuss the implications for the experiment . .
And you have already written the first three sentences of the full article: the first proposal of experimental search for @xmath1 violation effects in atoms was made almost 40 years ago @xcite .
the modern advanced experimental techniques realized in the experiments on electron s electric dipole moment ( edm ) are based on that idea and have the sensitivity of @xmath2 @xcite .
apart from the electron edm , experimental searches for the edm of the neutron are on - going @xcite ..
Please generate the next two sentences of the article | current sensitivity allows for detection of electric dipole moment ( edm ) of the neutron at the level of @xmath3 @xmath4 . from theoretical point of view
, a non - zero edm could imply non - zero values for the qcd @xmath5-term as the latter can induce an edm @xcite . an attractive idea to enhance the experimental sensitivity to the electron edm |
9,859 | Suppose that you have an abstract for a scientific paper: observations of grb _ 100724b _ with the fermi gamma - ray burst monitor ( gbm ) find that the spectrum is dominated by the typical band functional form , which is usually taken to represent a non - thermal emission component , but also includes a statistically highly significant thermal spectral contribution . the simultaneous observation of the thermal and non - thermal components allows us to confidently identify the two emission components .
the fact that these seem to vary independently favors the idea that the thermal component is of photospheric origin while the dominant non - thermal emission occurs at larger radii .
our results imply either a very high efficiency for the non - thermal process , or a very small size of the region at the base of the flow , both quite challenging for the standard fireball model .
these problems are resolved if the jet is initially highly magnetized and has a substantial poynting flux . .
And you have already written the first three sentences of the full article: the prompt emission detected from gamma - ray bursts ( grbs ) is believed to originate at large distances from the central engine , from within an ultrarelativistic outflow @xcite .
this ultra - relativistic motion is necessary to avoid strong @xmath0 annihilation , a signature that is not observed ( see , e.g. , * ? ? ?
thermal emission is naturally expected in such a scenario . indeed , since the densities at the base of the relativistic flow are very large , the medium is optically thick to radiation owing to thomson scattering by entrained electrons ..
Please generate the next two sentences of the article | the optical depth decreases during the relativistic expansion and the outflow eventually becomes transparent for its own radiation , at the photospheric radius .
any internal energy that is still carried out by the flow can be radiated at the photosphere and will be observed as a thermal component in the prompt spectrum . this expected photospheric emission in grb spectra |
9,860 | Suppose that you have an abstract for a scientific paper: we investigate , whether the alleged failure of standard photoionization codes of the diffuse ionized gas ( dig ) is simply caused by geometrical effects and the insufficient treatment of the radiative transfer .
standard photoionization models are applicable only to homogeneous and spherical symmetric nebulae with central ionizing stars , whereas the geometry of disk galaxies requires a 3d distribution of ionizing sources in the disk which illuminate the halo .
this change in geometry together with a proper radiative transfer model is expected to substantially influence ionization conditions .
therefore , we developed a new and sophisticated 3d monte carlo photoionization code , called _ soap _
( simulations of astrophysical plasmas ) , by adapting an existing 1d code for hii - regions @xcite such , that it self - consistently models a 3d disk galaxy with a gaseous dig halo .
first results from a simple ( dust - free ) model with exponentially decreasing gas densities are presented and the predicted ionization structure of disk and halo is discussed .
theoretical line ratios agree well with observed ones , e.g , . for the halo of ngc891 .
moreover , the fraction of ionizing photons leaving the halo of the galaxy is plotted as a function of varying gas densities .
this quantity will be of particular importance for forthcoming studies , because rough estimates indicate that about 7% ionizing photons escape from the halo and contribute to the ionization of the igm . given the relatively large number density of normal spiral galaxies , ob - stars could have a much stronger impact on the ionization of the igm than agn or qsos . .
And you have already written the first three sentences of the full article: various observational and theoretical studies have been carried out which aimed at the investigation of possible ionization mechanisms of the diffuse ionized gas ( dig , also called interstellar froth @xcite ) in the milky way ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ) as well as in external galaxies ( e.g. , * ? ? ? |
9,861 | Suppose that you have an abstract for a scientific paper: the radial structure of the continuous spectrum of shear alfvn waves is calculated in this paper within the separatrix of a magnetic island .
geometrical effects due to the noncircularity of the flux surface s cross section are retained to all orders . on the other hand , we keep only curvature effects responsible for the beta - induced gap in the low - frequency part of the continuous spectrum . modes with different helicity from that of the magnetic island are considered .
the main result is that , inside a magnetic island , there is a continuous spectrum very similar to that of tokamak plasmas , where a generalized safety factor @xmath0 can be defined and where a wide frequency gap is formed , analogous to the ellipticity induced alfvn eigenmode gap in tokamaks .
the presence of this gap is due to the strong eccentricity of the island cross section .
the importance of the existence of such a gap is recognized in potentially hosting magnetic - island induced alfvn eigenmodes ( miae ) . due to the frequency dependence of the shear alfvn wave continuum on the magnetic - island size , the possibility of utilizing miae frequency scalings as a novel magnetic - island diagnostic is also discussed .
+ pacs : 52.55.tn , 52.35.bj .
And you have already written the first three sentences of the full article: shear alfvn waves ( saw ) are electromagnetic plasma waves propagating as transverse waves along the magnetic field , with the characteristic alfvn velocity @xmath1 ( @xmath2 is the magnetic field and @xmath3 the mass density of the plasma ) . in fusion plasmas , fast ions in the mev energy range have velocities comparable with the typical alfvn speed . in addition , saw group velocity is directed along the magnetic field line and , therefore , fast ions can stay in resonance and effectively exchange energy with the wave @xcite . saw in a nonuniform equilibrium experience collisionless dissipation ( _ continuum damping _
@xcite ) , due to singular structures that are formed where the saw continuum is resonantly excited . in tokamaks ,
the magnetic field intensity varies along the field line ..
Please generate the next two sentences of the article | this creates gaps in the saw continuous spectrum @xcite due to translational symmetry breaking , analogous to electrons traveling in a periodic lattice @xcite .
two types of collective shear alfvn instabilities exist in tokamak plasmas : energetic - particle continuum modes ( epm ) @xcite , with frequency determined by fast particle characteristic motions , and discrete alfvn eigenmodes ( ae ) , with a frequency inside saw continuum gaps @xcite . |
9,862 | Suppose that you have an abstract for a scientific paper: using molecular dynamics simulations we investigate the ability of an analytical three - dimensional double well in reproducing static and dynamic anomalies found experimentally in liquid water .
we find anomalous behavior in the stable region of the phase diagram if the outer minimum is deeper than the inner minimum . in the case of a deeper inner minimum , anomalous behavior is also present but inside the unstable region .
core - softened potential , diffusion .
And you have already written the first three sentences of the full article: the prediction of structural , dynamic and thermodynamic properties and the phase behavior of fluids based solely on the shape of the intermolecular interaction potential is an important goal in the study of liquids and in the understanding of the peculiarities of the liquid state .
the simplicity of this surmise has not only theoretical interest but also practical consequences@xcite . in spite of these motivations and precepts of developing a much better molecular - level picture of the liquid matter , this goal is far from being achieved .
although for some simple potential the use of integral equations in the form of hypernetted - chain approximation can give an estimate of the phase stability @xcite , the mathematical complexity of the interaction potentials used even for simple liquid does not allow an analytical approach ..
Please generate the next two sentences of the article | despite of this , some progress can be made choosing only liquids that share the same type of structure , for instance , a tetrahedrical local structure .
the most familiar tetrahedral liquid is water not only due to its abundance but also because of the occurrence of some remarkable features such as the presence of structural , dynamic or thermodynamic anomalies . |
9,863 | Suppose that you have an abstract for a scientific paper: we derive new limits on light stops from diboson resonance searches in the @xmath0 , @xmath1 , @xmath2 , @xmath3 and @xmath4 channels from the first run of the lhc .
if the two - body decays of the light stop are mildly suppressed or kinematically forbidden , stoponium bound states will form in @xmath5 collisions and subsequently decay via the pair annihilation of the constituent stops to diboson final states , yielding striking resonance signatures .
remarkably , we find that stoponium searches are highly complementary to direct collider searches and indirect probes of light stops such as higgs coupling measurements . using an empirical quarkonia potential model and including the first two @xmath6-wave stoponium states , we find that in the decoupling limit @xmath7 gev is excluded for _ any _ value of the stop mixing angle and heavy stop mass by the combination of the latest resonance searches and the indirect constraints .
the @xmath8 searches are the most complementary to the indirect constraints , probing the stop `` blind spot '' parameter region in which the @xmath9 trilinear coupling is small .
interestingly , we also find that the @xmath10 searches give a stronger constraint , @xmath11 gev , if the stop is primarily left - handed . for a scenario with a bino lsp and stop nlsp , several gaps in the direct collider searches for stops can unambiguously be filled with the next run of the lhc . for a stop lsp decaying through an r - parity violating @xmath12 coupling
, the stoponium searches can fill the gap 100 gev @xmath13 gev in the direct searches for couplings @xmath14 . .
And you have already written the first three sentences of the full article: light stops are a quintessential feature of a natural supersymmetric theory @xcite , being responsible for the cancellation of the dominant higgs mass quadratic divergence coming from the top quark . however , after run 1 of the lhc the possible existence of light stops has been strongly constrained by a suite of dedicated searches by atlas and cms @xcite .
for instance , in a simplified scenario containing a neutralino as the lightest supersymmetric particle ( lsp ) and the stop as the next - to - lightest supersymmetric particle ( nlsp ) , with a few gaps and caveats , stop masses as high as @xmath15 gev and lsp masses as high as @xmath16 gev have been excluded @xcite . still , as is always the case with direct searches , the limits depend strongly on the spectrum and decays of the stops , and there remain open windows in which a light stop can hide from lhc searches .
examples include compressed @xcite or stealth @xcite stops and r - parity violating stop decays @xcite ..
Please generate the next two sentences of the article | it is therefore critical to continue to develop new strategies to directly search for light stops @xcite .
another opportunity to probe light stops is presented when the stop is long lived , which naturally occurs in a number of motivated scenarios . |
9,864 | Suppose that you have an abstract for a scientific paper: the production of photometric light curves from astronomical images is a very time - consuming task , taking several hours or even days .
larger data sets improve the resolution of the light curve , however , the time requirement scales with data volume .
the data analysis is often made more difficult by factors such as a lack of suitable calibration sources and the need to correct for variations in observing conditions from one image to another .
often these variations are unpredictable and corrections are based on experience and intuition .
the high efficiency image detection & identification ( heidi ) pipeline software rapidly processes sets of astronomical images , taking only a few minutes .
heidi automatically selects multiple sources for calibrating the images using a selection algorithm that provides a reliable means of correcting for variations between images in a time series .
the algorithm takes into account that some sources may intrinsically vary on short time scales and excludes these from being used as calibration sources .
heidi processes a set of images from an entire night of observation , analyses the variations in brightness of the target objects and produces a light curve all in a matter of minutes .
heidi has been tested on three different time series of 50 images each of asteroid 939 isberga and has produced consistent high quality photometric light curves in a fraction of the usual processing time .
the software can also be used for other transient sources , e.g. gamma - ray burst optical afterglows , gaia transient candidates .
heidi is implemented in the programming language python and processes time series astronomical images in fits format with minimal user interaction .
heidi processes up to 1000 images per run in the standard configuration .
this limit can be easily increased , with the only real limit being system capacity , e.g. disk space , memory .
heidi is not telescope - dependent and will process images even in the case that no telescope....
And you have already written the first three sentences of the full article: the process of analysing a time series of astronomical images to measure the variations in brightness of an object over time and to calibrate those variations against reference sources is a very time - consuming task .
an accurate understanding of the variation in brightness of an object over time , i.e. its photometric light curve , allows modelling of key characteristics of the object ( e.g. the shape of an asteroid , the type of a supernova or gamma - ray burst optical afterglow ) .
the measurement process often varies only little depending on the type of object , whether it is an asteroid tumbling through space , a supernova or the rapidly fading optical afterglow from a gamma - ray burst ..
Please generate the next two sentences of the article | the process usually involves examining the images in the time series for at least one suitable reference source in order to calibrate the brightness .
some processes require the reference sources to have particular characteristics , e.g. a specific spectral class or magnitude . |
9,865 | Suppose that you have an abstract for a scientific paper: infrared ( ir ) blocking filters are crucial for controlling the radiative loading on cryogenic systems and for optimizing the sensitivity of bolometric detectors in the far - ir .
we present a new ir filter approach based on a combination of patterned frequency selective structures on silicon and a thin ( 50 @xmath0 thick ) absorptive composite based on powdered reststrahlen absorbing materials . for a 300 k blackbody ,
this combination reflects @xmath150% of the incoming light and blocks > 99.8% of the total power with negligible thermal gradients and excellent low frequency transmission .
this allows for a reduction in the ir thermal loading to negligible levels in a single cold filter .
these composite filters are fabricated on silicon substrates which provide excellent thermal transport laterally through the filter and ensure that the entire area of the absorptive filter stays near the bath temperature .
a metamaterial antireflection coating cut into these substrates reduces in - band reflections to below 1% , and the in - band absorption of the powder mix is below 1% for signal bands below 750 ghz .
this type of filter can be directly incorporated into silicon refractive optical elements . .
And you have already written the first three sentences of the full article: [ [ section ] ] ir blocking filters are critical for optimizing bolometer - based receivers in the millimeter and submillimeter spectral region . in these bands ,
the ir power emitted from the telescope and surroundings ( typically 250 - 300 k for ground and balloon - based instruments ) is much brighter than the sky background .
it is therefore crucial to control this out - of - band power ..
Please generate the next two sentences of the article | filters serve to substantially reduce what would be a dominant source of noise and minimize the radiative loading on the cryogenic system .
in addition , the filters must not significantly radiate , reflect , or scatter in the band of interest . |
9,866 | Suppose that you have an abstract for a scientific paper: we classify ( possibly noncommutative ) algebras of low rank over a domain @xmath0 .
we first review results for algebras of rank 2 and for finite - dimensional division algebras over @xmath1 .
these results motivate us to consider which algebras possess a standard involution .
our main result is that algebras of rank 3 are either commutative or possess a standard involution .
thanks to my supportive parents barry and mara . comments and encouragement from my fellow master s degree students have been invaluable , particularly eric roma , mike klug , jared krogsrud , sam schiavone , brian lang , andy reagan , and jonathan godbout . i could not have completed this work without the background and skills i developed in my coursework , especially in the algebra and real analysis sequences taught by professors john voight and jonathan sands , respectively .
thank you to the members of the committee and to my advisor professor john voight , without whose guidance , tireless editing , and infectious energy this thesis would not exist .
thanks above all to my beloved wife , andrea . .
And you have already written the first three sentences of the full article: in a vector space we enjoy the ability to combine vectors by addition and to scale by elements of a field .
but we can not , in general , multiply vectors .
if we upgrade " our space to permit multiplication ( subject to a few restrictions ) , we obtain an algebra . generalizing from vector spaces to free modules over a domain , we make the following definition ..
Please generate the next two sentences of the article | let @xmath0 be a domain ( with @xmath2 ) .
@xmath0-_algebra _ is an associative ring @xmath3 ( with @xmath2 ) equipped with an embedding of @xmath0 into the center of @xmath3 that is free as an @xmath0-module . |
9,867 | Suppose that you have an abstract for a scientific paper: we have developed an automatic search procedure to identify low - energy spectral features in grbs . we have searched 133,000 spectra from 117 bright bursts and have identified 12 candidate features with significances ranging from our threshold of @xmath0 5e@xmath15 to @xmath0 1e@xmath17 .
several of the candidates have been examined in detail , including some with data from more than one batse spectroscopy detector .
the evidence for spectral features appears good ; however , the features have not conclusively been shown to be narrow lines .
= = = 1=1=0pt = 2=2=0pt .
And you have already written the first three sentences of the full article: narrow , low - energy ( @xmath2 kev ) spectral lines in grbs have been reported using the data of several instruments ( e.g. , see review @xcite ) . based on these reports , the batse team expected lines to be easy to find and looked for them manually @xcite .
the reality was different : lines were not obvious in burst spectra . in order to be sure that the manual search had not missed any lines
, we implemented a comprehensive , automatic computer search @xcite ..
Please generate the next two sentences of the article | bursts with at least one spectrum with a normed signal - to - noise ratio ( snr ) @xcite near 40 kev above 5.0 are searched . for each burst , we form spectra from each individual spectral record , every pair , triple , etc . the spectra so formed overlap in many cases .
once a burst is selected for the search , spectra are searched regardless of the presence of burst flux low snr spectra serve as controls . |
9,868 | Suppose that you have an abstract for a scientific paper: we show how the two - band nature of superconductivity in noncentrosymmetric compounds leads to a variety of novel nonuniform superconducting states induced by a magnetic field . at low fields ,
a two - band helical state is realized , with a distinctly non - bcs quasiparticle spectrum . at high fields ,
the superconducting state becomes unstable towards the formation of a lattice of topological phase solitons . .
And you have already written the first three sentences of the full article: the recent revival of interest in the properties of two - band ( or , more generally , multiband ) superconductors has been largely stimulated by the discovery of superconductivity in mgb@xmath0 ( ref . ) .
other candidates for multiband superconductivity include nickel borocarbides ( ref . ) , nbse@xmath0 ( ref . ) , cecoin@xmath1 ( ref . ) , and also the iron - based high - temperature superconductors , see ref . for a review .
these discoveries have shown that multiband superconductivity , which is characterized by a significant difference in the order parameter magnitudes and/or phases in different bands , might be a much more common phenomenon than it was previously thought ..
Please generate the next two sentences of the article | one important class of multiband superconductors is noncentrosymmetric compounds with a strong spin - orbit ( so ) coupling of conduction electrons with the lattice . since the discovery of superconductivity in cept@xmath2si ( ref . ) , the list of noncentrosymmetric superconductors has grown to include dozens of materials , such as uir ( ref . ) , cerhsi@xmath2 ( ref . ) , ceirsi@xmath2 ( ref . ) , y@xmath0c@xmath2 ( ref . ) , li@xmath0(pd@xmath3,pt@xmath4)@xmath2b ( ref . ) , and many others . in noncentrosymmetric crystals ,
the bloch bands are split by the so coupling and the cooper pairing of electrons from different bands is suppressed , resulting in an effectively two - band picture of superconductivity . |
9,869 | Suppose that you have an abstract for a scientific paper: we present an agent - based model inspired by the evolutionary minority game ( emg ) , albeit strongly adapted to the case of competition for limited resources in ecology .
the agents in this game become able , after some time , to predict the _ a priori _ best option as a result of an evolution - driven learning process .
we show that a self - segregated social structure can emerge from this process , i.e. , extreme learning strategies are always favoured while intermediate learning strategies tend to die out . this result may contribute to understanding some levels of organization and cooperative behaviour in ecological and social systems .
we use the ideas and results reported here to discuss an issue of current interest in ecology : the mistimings in egg laying observed for some species of bird as a consequence of their slower rate of adaptation to climate change in comparison with that shown by their prey .
our model supports the hypothesis that habitat - specific constraints could explain why different populations are adapting differently to this situation , in agreement with recent experiments . , and evolutionary learning , climate change , limited resources , predator - prey .
And you have already written the first three sentences of the full article: minority games ( challet and zhang , 1998 ) , and more recently evolutionary minority games ( emg ) ( johnson et .
al . , 1999a ; johnson et .
al . , 2000 ; de cara et ..
Please generate the next two sentences of the article | al . , 2000 ; johnson et .
al . , 2003 ; hod and nakar , 2002 ; hod , 2003 ; sysi - aho et . |
9,870 | Suppose that you have an abstract for a scientific paper: we present a second epoch of observations of the 44 ghz class i methanol maser line toward the star forming region omc-2 .
the observations were carried out with the very large array , and constitute one of the first successful zeeman effect detections with the new widar correlator . comparing to the result of our earlier epoch of data for this region , we find that the intensity of the maser increased by 50% , but the magnetic field value has stayed the same , within the errors .
this suggests that the methanol maser may be tracing the large - scale magnetic field that is not affected by the bulk gas motions or turbulence on smaller scales that is causing the change in maser intensity . .
And you have already written the first three sentences of the full article: the ability to carry out high angular resolution observations of several types of masers has increased tremendously due to the availability of interferometers at several different frequencies .
for example , 36 ghz methanol maser observations are now routine with the karl g. jansky very large array ( vla ) , e.g. , @xcite and @xcite .
since masers allow for the observation of magnetic fields at high angular resolution via the zeeman effect , there has often been speculation on whether they trace the large - scale magnetic field or only the field within the small - scale environments in which such masers form ( @xcite ; @xcite ; @xcite ) ..
Please generate the next two sentences of the article | since the observation of magnetic fields is challenging in general ( e.g. , @xcite ) , the ability to measure the large - scale magnetic field with masers would prove to be invaluable , especially because magnetic fields play such an important role in the process of star formation ( e.g. , @xcite ; @xcite ) . at a distance of 450
pc ( @xcite ) , the orion molecular cloud 2 ( omc-2 ) is considered one of the nearest intermediate - mass star forming regions ( e.g. , @xcite ) . this region is located at an angular distance of 12@xmath0 northeast of the trapezium ob cluster , and along with omc-3 , it is part of a single long filament in orion ( @xcite ) . in 2011 , we reported the discovery of the zeeman effect in the 44 ghz class i ch@xmath1oh maser line toward omc-2 ( @xcite ) . in this paper , we report follow - up observations on the zeeman effect of this methanol maser line . |
9,871 | Suppose that you have an abstract for a scientific paper: we investigate the impact of starspots on the evolution of late - type stars during the pre - main sequence ( pre - ms ) .
we find that heavy spot coverage increases the radii of stars by 4 - 10% , consistent with inflation factors in eclipsing binary systems , and suppresses the rate of pre - ms lithium depletion , leading to a dispersion in zero - age ms li abundance ( comparable to observed spreads ) if a range of spot properties exist within clusters from 3 - 10 myr .
this concordance with data implies that spots induce a range of radii at fixed mass during the pre - ms .
these spots decrease the luminosity and of stars , leading to a displacement on the hr diagram .
this displacement causes isochrone derived masses and ages to be systematically under - estimated , and can lead to the spurious appearance of an age spread in a co - eval population . .
And you have already written the first three sentences of the full article: despite recent improvements in stellar modeling , several notable discrepancies remain between theoretical predictions of low mass stellar properties and high precision measurements from techniques such as eclipsing binary ( eb ) analysis and interferometry .
one such discrepancy is the inflated radius problem , where young , low - mass stellar radii are observed to be larger by @xmath0% than theoretical predictions .
a second discrepancy is between the observed lithium patterns of young clusters such as the pleiades , which host abundance dispersions in excess of an order - of - magnitude at fixed , and standard model theoretical predictions , which anticipate no dispersion at fixed ..
Please generate the next two sentences of the article | notably , the most li rich stars in the pleiades are also the most rapidly rotating , the opposite sense of the correlation expected from rotational mixing .
in two recent papers , we suggested that if some mechanism induced inflated radii in rapidly rotating , low - mass stars during the pre - ms , then the li destruction rate in the inflated stars would be suppressed , and one could explain both the inflated radius problem and the li - rotation correlation in the pleiades , with a single mechanism ( ( * ? ? ? |
9,872 | Suppose that you have an abstract for a scientific paper: we study the problem of conjunctive query evaluation over sets of queries ; this problem is formulated here as the relational homomorphism problem over a set of structures @xmath0 , wherein each instance must be a pair of structures such that the first structure is an element of @xmath0 .
we present a comprehensive complexity classification of these problems , which strongly links graph - theoretic properties of @xmath0 to the complexity of the corresponding homomorphism problem .
in particular , we define a binary relation on graph classes and completely describe the resulting hierarchy given by this relation .
this binary relation is defined in terms of a notion which we call graph deconstruction and which is a variant of the well - known notion of tree decomposition .
we then use this graph hierarchy to infer a complexity hierarchy of homomorphism problems which is comprehensive up to a computationally very weak notion of reduction , namely , a parameterized form of quantifier - free reductions .
we obtain a significantly refined complexity classification of homomorphism problems , as well as a unifying , modular , and conceptually clean treatment of existing complexity classifications .
we also present and develop the theory of pebble games which solve the homomorphism problems where the cores of the structures in @xmath0 have bounded tree depth ; as a fruit of this development , we characterize the homomorphism problems solvable in logarithmic space .
we also use our framework to classify the complexity of model checking existential sentences having bounded quantifier rank .
[ section ] [ theorem]conjecture [ theorem]corollary [ theorem]example [ theorem]examples [ theorem]proposition [ theorem]proposition [ theorem]lemma [ theorem]definition [ theorem]remark .
And you have already written the first three sentences of the full article: _ conjunctive queries _ are basic and heavily studied database queries , and can be viewed logically as formulas consisting of a sequence of existentially quantified variables , followed by a conjunction of atomic formulas . since the 1977 article of chandra and merlin @xcite ,
complexity - theoretic aspects of conjunctive queries have been a research subject of persistent and enduring interest which continues to the present day ( as discussed and evidenced , for example , by the works @xcite ) . in this article , we study _ conjunctive query evaluation _ , which is the problem of evaluating a conjunctive query on a relational structure .
conjunctive query evaluation is indeed equivalent to a number of well - known problems , including the homomorphism problem on relational structures , the constraint satisfaction problem , and conjunctive query containment @xcite ..
Please generate the next two sentences of the article | that this problem appears in many equivalent guises attests to its fundamental , primal nature , and this problem has correspondingly been approached and studied from a wide variety of perspectives and motivations . as has been eloquently articulated in the literature
, the employment of classical complexity notions such as polynomial - time tractability to grade the complexity of conjunctive query evaluation is not totally satisfactory : a typical scenario for example , in the database context is the evaluation of a relatively short query on a relatively large structure . |
9,873 | Suppose that you have an abstract for a scientific paper: radical - ion pairs and their reactions have triggered the study of quantum effects in biological systems .
this is because they exhibit a number of effects best understood within quantum information science , and at the same time are central in understanding the avian magnetic compass and the spin transport dynamics in photosynthetic reaction centers .
here we address radical - pair reactions from the perspective of quantum metrology .
since the coherent spin motion of radical - pairs is effected by an external magnetic field , these spin - dependent reactions essentially realize a biochemical magnetometer . using the quantum fisher information , we find the fundamental quantum limits to the magnetic sensitivity of radical - pair magnetometers . we then explore how well the usual measurement scheme considered in radical - pair reactions , the measurement of reaction yields , approaches the fundamental limits . in doing so , we find the optimal hyperfine interaction hamiltonian that leads to the best magnetic sensitivity as obtained from reaction yields .
this is still an order of magnitude smaller than the absolute quantum limit .
finally , we demonstrate that with a realistic quantum reaction control reminding of ramsey interferometry , here presented as a quantum circuit involving the spin - exchange interaction and a recently proposed molecular switch , we can approach the fundamental quantum limit within a factor of 2 .
this work opens the application of well - advanced quantum metrology methods to biological systems . .
And you have already written the first three sentences of the full article: the quantum dynamics of the radical - pair mechanism @xcite , underlying the avian magnetic compass @xcite and spin transport in photosynthetic reaction centers @xcite , have recently attracted the attention of the quantum physics community @xcite , since it was shown @xcite that radical - pairs offer an ideal system to study quantum coherence effects and explore quantum information processing in a complex biochemical setting .
radical - pair reactions consist of a coherent spin motion in a multi - spin system embedded in a biomolecule , interrupted by an electron transfer that results in the spin - dependent charge recombination of the radical - ion - pair and the termination of the reaction .
it is known that the coherent spin motion as well as the measurable reaction yields in radical - pair reactions are also influenced by the external magnetic field through the unpaired electrons zeeman interaction ..
Please generate the next two sentences of the article | hence radical - pair reactions are no different than other quantum systems used to measure a classical parameter , as for example are the well - developed atomic magnetometers @xcite using e.g. alkali vapors @xcite or nitrogen vacancy centers @xcite .
central in these studies have been the fundamental measurement precision limits set by the quantum dynamics of the system under consideration . |
9,874 | Suppose that you have an abstract for a scientific paper: @xmath0-detected nmr ( @xmath0-nmr ) has been used to study vortex lattice disorder near the surface of the high-@xmath1 superconductor yba@xmath2cu@xmath3o@xmath4 ( ybco ) .
the magnetic field distribution from the vortex lattice was detected by implanting a low energy beam of highly polarized @xmath5li@xmath6 into a thin overlayer of silver on optimally doped , twinned and detwinned ybco samples .
the resonance in ag broadens significantly below the transition temperature @xmath1 as expected from the emerging field lines of the vortex lattice in ybco . however , the lineshape is more symmetric and the dependence on the applied magnetic field is much weaker than expected from an ideal vortex lattice , indicating that the vortex density varies across the face of the sample , likely due to pinning at twin boundaries . at low temperatures
the broadening from such disorder does not scale with the superfluid density . .
And you have already written the first three sentences of the full article: the vortex state of cuprate superconductors is of central importance in understanding high-@xmath1 superconductivity ( htsc ) .
one the most well studied quantities is the internal magnetic field distribution @xmath7 associated with the vortex lattice ( vl).@xcite as discussed below , several methods can be used to measure @xmath7 , which depends on the london penetration depth @xmath8 , the coherence length @xmath9,@xcite and , to a lesser extent , the internal structure of the vortices,@xcite and non - linear and non - local effects.@xcite the form of @xmath7 has a distinctive asymmetric shape due to the spatial magnetic inhomogeneity characteristic of an ordered two - dimensional ( 2d ) lattice of vortices .
one basic feature in @xmath7 is a prominent high field tail associated with the vortex cores , which depends on the magnitude of @xmath9 ..
Please generate the next two sentences of the article | there is also a saddle point in the local field profile located between two vortices .
this gives rise to a van hove singularity or sharp peak in @xmath7 below the average field . |
9,875 | Suppose that you have an abstract for a scientific paper: we describe a method to compute thermodynamic quantities in the harmonic approximation for identical bosons and fermions in an external confining field .
we use the canonical partition function where only energies and their degeneracies enter .
the number of states of given energy and symmetry is found by separating the center of mass motion , and counting the remaining states of given symmetry and excitation energy of the relative motion .
the oscillator frequencies that enter the harmonic hamiltonian can be derived from realistic model parameters and the method corresponds to an effective interaction approach based on harmonic interactions . to demonstrate the method
, we apply it to systems in two dimensions .
numerical calculations are compared to a brute force method that is considerably more computationally intensive . .
And you have already written the first three sentences of the full article: the many - body problem can not be solved exactly for realistic interactions and systems .
numerous approximations have been formulated and applied over the years .
one of the problems is that many particles require a large hilbert space to allow for the many possible correlations ..
Please generate the next two sentences of the article | in fact , the space typically grows exponentially with the particle number .
the necessary reduction of the hilbert space to obtain a tractable problem has to be accompanied by a correponding transformation of the interaction which in turn has to be used in the smaller space . |
9,876 | Suppose that you have an abstract for a scientific paper: we used methods of bayesian statistical inference and the principle of maximum entropy to analytically continue imaginary - time green s function generated in quantum monte carlo simulations to obtain the real - time green s functions . for test problems , we considered chains of harmonic and anharmonic oscillators whose properties we simulated by a hybrid path - integral quantum monte carlo method . from the imaginary - time displacement - displacement green s function , we first obtained its spectral density . for harmonic oscillators
, we demonstrated the peaks of this function were in the correct position and their area satisfied a sum rule .
additionally , as a function of wavenumber , the peak positions followed the correct dispersion relation . for a double - well oscillator
, we demonstrated the peak location correctly predicted the tunnel splitting . transforming the spectral densities to real - time green s functions ,
we conclude that we can predict the real - time dynamics for length of times corresponding to 5 to 10 times the natural period of the model .
the length of time was limited by an overbroadening of the peaks in the spectral density caused by the simulation algorithm . .
And you have already written the first three sentences of the full article: one of the goals for doing computer simulations is the production of information useful in the interpretation and design of experiments .
notwithstanding important issues regarding hamiltonian selection and parameterization , the interface of simulations with experiment is particularly challenging for quantum systems . the current monte carlo algorithms , whether they impose quantum particle statistics constraints or not , are performed either in real - time @xmath0 or in imaginary - time ( euclidean time ) @xmath1 . in real - time , the propagator @xmath2 for a system , described by a hamiltonian @xmath3 , oscillates wildly at long - times .
analytically , these rapid oscillations self - cancel , but a monte carlo process , as it is typically used , has difficulty achieving this cancellation . as a consequence , modifications of the basic algorithms have been proposed to extend the simulations as long as possible in the real - time domain @xcite . with these new algorithms ,.
Please generate the next two sentences of the article | simulations typically produce dynamics extending to 2 to 3 times the natural periods of the systems . in imaginary - time , the propagator @xmath4 is diffusive and the rapid oscillations are avoided .
correlations functions @xmath5 , however , are now a function of imaginary - time , and such functions do not easily convey the actual dynamics of the system . in principle , real - time correlation ( green s ) functions @xmath6 can be obtained from the imaginary - time ones by the process of analytic continuation . in practice , this process is difficult because it is ill - posed and because the monte carlo data is incomplete and noisy . |
9,877 | Suppose that you have an abstract for a scientific paper: low - energy electron collisions with o@xmath0 molecules are studied using the fixed - bond r - matrix method .
in addition to the o@xmath0 @xmath1 ground state , integrated cross sections are calculated for elecron collisions with the @xmath2 and @xmath3 excited states of o@xmath0 molecules .
13 target electronic states of o@xmath0 are included in the model within a valence configuration interaction representations of the target states .
elastic cross sections for the @xmath2 and @xmath3 excited states are similar to the cross sections for the @xmath1 ground state . as in case of excitation from the @xmath1 state , the o@xmath4 @xmath5 resonance makes the dominant contribution to excitation cross sections from the @xmath2 and @xmath3 states .
the magnitude of excitation cross sections from the @xmath2 state to the @xmath3 state is about 10 time larger than the corresponding cross sections from the @xmath1 to the @xmath3 state . for this @xmath2 @xmath6
@xmath3 transition , our cross section at 4.5 ev agrees well with the available experimental value .
these results should be important for models of plasma discharge chemistry which often requires cross sections between the excited electronic states of o@xmath0 . .
And you have already written the first three sentences of the full article: an understanding of electron collision processes with oxygen molecules is important because of its role in chemistry of electrical discharge and the upper atmosphere . in recent attempts to an operate electrical discharge oxygen - iodine laser ,
a population inversion of iodine atoms was achieved by a near resonant energy transfer via the @xmath7 @xmath8 @xmath9 process .
in contrast to the traditional liquid chemistry singlet oxygen generator @xcite , recent studies @xcite utilize flowing electric discharges where electron collisions with o@xmath0 excited electronic states can be important @xcite . in such conditions ,.
Please generate the next two sentences of the article | even highly excited metastable states of o@xmath0(@xmath10 , @xmath11 , @xmath12 ) may play roles @xcite , in addition to the lower o@xmath0 @xmath2 and @xmath3 excited states .
however , most previous work has concentrated on electron collisions with the o@xmath13 ground state , so our knowledge of electron impact transitions from the o@xmath14 and @xmath3 excited states is limited . the past experimental and theoretical works concerning electron o@xmath0(@xmath15 , @xmath2 ) collisions were summarized by brunger and buckman @xcite . |
9,878 | Suppose that you have an abstract for a scientific paper: a pixel detector with a cvd diamond sensor has been studied in a 180 gev / c pion beam .
the charge collection properties of the diamond sensor were studied as a function of the track position , which was measured with a silicon microstrip telescope .
non - uniformities were observed on a length scale comparable to the diamond crystallites size . in some regions of the sensor , the charge drift appears to have a component parallel to the sensor surface ( i.e. , normal to the applied electric field ) resulting in systematic residuals between the track position and the hits position as large as 40 @xmath0 m .
a numerical simulation of the charge drift in polycrystalline diamond was developed to compute the signal induced on the electrodes by the electrons and holes released by the passing particles .
the simulation takes into account the crystallite structure , non - uniform trapping across the sensor , diffusion and polarization effects .
it is in qualitative agreement with the data .
additional lateral electric field components result from the non - uniform trapping of charges in the bulk .
these provide a good explanation for the large residuals observed . , , , , , diamond pixel detector , non - uniform charge collection 29.40.wk , 29.40.gx .
And you have already written the first three sentences of the full article: in the last decade the quality of chemical vapor deposited ( cvd ) diamond for particle detectors has greatly improved , and the use of this material has become a potentially attractive option for vertex detectors at high luminosity colliders ( such as the lhc after the proposed luminosity upgrade @xcite ) promising to provide the radiation resistance needed for the challenging particle fluxes expected .
diamond detectors are believed to be more radiation - hard than silicon @xcite . even after radiation exposures in excess of @xmath1
they can be operated at room temperature without significant leakage current ..
Please generate the next two sentences of the article | a loss in the charge signal of about 40% was observed with pion / proton radiation of @xmath2 @xcite . with neutrons a loss of 30%
was observed at a fluence of @xmath3 @xcite . |
9,879 | Suppose that you have an abstract for a scientific paper: we explore the computation of high - harmonic generation spectra by means of gaussian basis sets in approaches propagating the time - dependent schrdinger equation .
we investigate the efficiency of gaussian functions specifically designed for the description of the continuum proposed by kaufmann _
et al . _ [ j. phys .
b * 22 * , 2223 ( 1989 ) ] .
we assess the range of applicability of this approach by studying the hydrogen atom , i.e. the simplest atom for which `` exact '' calculations on a grid can be performed .
we notably study the effect of increasing the basis set cardinal number , the number of diffuse basis functions , and the number of gaussian pseudo - continuum basis functions for various laser parameters .
our results show that the latter significantly improve the description of the low - lying continuum states , and provide a satisfactory agreement with grid calculations for laser wavelengths @xmath0 = 800 and 1064 nm .
the kaufmann continuum functions therefore appear as a promising way of constructing gaussian basis sets for studying molecular electron dynamics in strong laser fields using time - dependent quantum - chemistry approaches . .
And you have already written the first three sentences of the full article: high - harmonic generation ( hhg ) is a highly nonlinear optical phenomenon @xcite of increasing interest because it can provide coherent xuv and soft x - ray radiation with attosecond ( @xmath1 s ) durations .
this property offers the opportunity to investigate unexplored research areas in atoms and molecules with unprecedented time resolution @xcite .
the hhg optical spectrum has a distinctive shape : a rapid decrease of the intensity for the low - order harmonics consistent with perturbation theory , followed by a broad plateau region where the harmonic intensity remains almost constant , and then an abrupt cutoff , beyond which almost no harmonics are observed ..
Please generate the next two sentences of the article | the hhg process can be understood by means of semi - classical pictures , such as the celebrated three - step model @xcite : ( i ) an electron escapes from the nuclei through tunnel ionization associated with the strong laser field , ( ii ) it is accelerated away by the laser field until the sign of the field changes , ( iii ) whereupon the electron is reaccelerated back to the nucleus , where it may emit a photon as it recombines to the ground state .
a key quantity emerging from the model is the maximum energy the field can provide to the electron , @xmath2 , where @xmath3 is the ionization potential and @xmath4 is the ponderomotive energy @xcite . |
9,880 | Suppose that you have an abstract for a scientific paper: we report our measurement of the rate of change of period with time ( @xmath0 ) for the 215s periodicity in the pulsating white dwarf g 117b15a , the most stable optical clock known . after 31 years of observations
, we have finally obtained a 4@xmath1 measurement @xmath2 .
taking into account the proper - motion effect of @xmath3 , we obtain a rate of change of period with time of @xmath4 .
this value is consistent with the cooling rate in our white dwarf models only for cores of c or c / o . with the refinement of the models ,
the observed rate of period change can be used to accurately measure the ratio of c / o in the core of the white dwarf . .
And you have already written the first three sentences of the full article: is a pulsating white dwarf with a hydrogen atmosphere , a dav , also called a zz ceti star @xcite .
these stars show multi - periodic non - radial @xmath5-mode pulsations that can be used to measure their internal properties and rate of evolution .
@xcite found the star was variable , and @xcite studied its light curve , finding 6 simultaneous pulsations ..
Please generate the next two sentences of the article | the dominant mode has a period of 215 s , a fractional amplitude of 22 mma ( milli - modulation amplitude = 1/1.086 milli magnitude ) , and is stable in amplitude and phase .
the other smaller pulsation modes vary in amplitude from night to night @xcite , suggesting the presence of unresolved components . because the davs appear to be normal stars except for their variability @xcite , i.e. , an evolutionary stage in the cooling of all white dwarfs , it is likely that the dav structural properties are representative of _ all _ da white dwarfs . |
9,881 | Suppose that you have an abstract for a scientific paper: we propose a quantum optics experiment where a single two - mode gaussian entangled state is used for realizing the paradigm of an amendable gaussian channel recently presented in phys .
rev . a , * 87 * , 062307 ( 2013 ) . depending on the choice of the experimental parameters the entanglement of the probe state
is preserved or not and the relative map belongs or not to the class of entanglement breaking channels .
the scheme has been optimized to be as simple as possible : it requires only a single active non - linear operation followed by four passive beam - splitters .
the effects of losses , detection inefficiencies and statistical errors are also taken into account , proving the feasibility of the experiment with current realistic resources . .
And you have already written the first three sentences of the full article: decoherence embodies the detrimental effects of noise on any quantum system whose coherence , in its widest sense , is smeared causing the loss of information of the initial state @xcite .
this represents a focal point in quantum information theory @xcite as it limits both the attainable fidelity and the variety of accessible protocols @xcite .
in particular , entanglement @xcite represents a fundamental resource in quantum computation @xcite and thus it should be protected against dechorence . in this regard ,.
Please generate the next two sentences of the article | the most undesirablefamily of quantum processes is given by the so - called entanglement breaking ( eb ) maps @xcite , under whose action any entanglement initially installed between the system and an external ancilla is completely lost .
these are maps acting on one component of an entangled pair leaving unperturbed the other . _ amendable channels _ strongly related to eb maps @xcite . |
9,882 | Suppose that you have an abstract for a scientific paper: we report the discovery of a quasi - periodic oscillation ( qpo ) in data obtained with the rossi x - ray timing explorer of the dipping and eclipsing low - mass x - ray binary exo 0748676 .
the qpo had a frequency between 0.58 and 2.44 hz changing on time scales of a few days , an rms amplitude between 8% and 12% , and was detected in the persistent emission , during dips and during type i x - ray bursts . during one observation , when the count rate was a factor 2 to 3 higher than otherwise , the qpo was not detected .
the strength of the qpo did not significantly depend on photon energy , and is consistent with being the same in the persistent emission , both during and outside the dips , and during type i x - ray bursts .
frequency shifts were observed during three of the four x - ray bursts .
we argue that the qpo is produced by the same mechanism as the qpo recently found by jonker et al .
( 1999 ) in 4u 132362 .
although the exact mechanism is not clear , it is most likely related to the high inclination of both systems .
an orbiting structure in the accretion disc that modulates the radiation from the central source seems the most promising mechanism . .
And you have already written the first three sentences of the full article: the low - mass x - ray binary ( lmxb ) exo 0748676 was discovered with _
exosat _ by parmar et al .
it showed periodic eclipses , irregular intensity dips , and type i x - ray bursts ( parmar et al . 1986 ) ..
Please generate the next two sentences of the article | the eclipses , due to obscuration of the central x - ray source by the companion star , occurred at a period of 3.82 hr . from the eclipse duration
an inclination of 75@xmath0 to 82@xmath0 was derived . |
9,883 | Suppose that you have an abstract for a scientific paper: we consider fluxon dynamics in a stack of inductively coupled long josephson junctions connected capacitively to a common resonant cavity at one of the boundaries .
we study , through theoretical and numerical analysis , the possibility for the cavity to induce a transition from the energetically favored state of spatially separated shuttling fluxons in the different junctions to a high velocity , high energy state of identical fluxon modes . .
And you have already written the first three sentences of the full article: thz emission from intrinsic josephson junctions of the bscco type has received much attention recently .
several experiments have been reported @xcite , in which thz radiation emitted from bscco single crystals were observed .
however in most cases the detected power is rather small , or the frequency is rather low , or the emitted radiation is detected indirectly on an on - chip detector ..
Please generate the next two sentences of the article | it has also been demonstrated that bscco can be considered a josephson junction with ac josephson effect even at frequencies as high as 2 thz @xcite . recently
a very convincing experiment was reported @xcite and it has attracted much focus and renewed experimental efforts . |
9,884 | Suppose that you have an abstract for a scientific paper: a quantum simulator based on ultracold optically trapped atoms for simulating the physics of atoms and molecules in ultrashort intense laser fields is introduced . the slowing down by about 13 orders of magnitude allows to watch in slow motion the tunneling and recollision processes that form the heart of attosecond science .
the extreme flexibility of the simulator promises a deeper understanding of strong - field physics , especially for many - body systems beyond the reach of classical computers .
the quantum simulator can experimentally straightforwardly be realized and is shown to recover the ionization characteristics of atoms in the different regimes of laser - matter interaction . in his renowned lecture , `` simulating physics with computers '' @xcite richard p. feynman suggested the use of quantum simulators , i.e. precisely controllable quantum systems , to simulate other quantum systems that can not be described theoretically due to their exponentially growing hilbert space .
for instance , the mott - insulator to superfluid phase transition in condensed - matter systems @xcite was predicted @xcite to be observable with ultracold atoms in an optical lattice and then successfully demonstrated @xcite .
also the higgs mechanism @xcite , high temperature superconductivity @xcite , or _
zitterbewegung _ @xcite ( to name just a few ) were successfully investigated by quantum simulation .
moreover , the quantum simulation of electrons in crystalline solids exposed to laser fields @xcite has been proposed .
strong - field physics has contributed considerably to the understanding of the light - matter interaction .
the progress leading to pulses on the attosecond timescale @xcite has even raised visions of real - time imaging of molecular processes @xcite and orbital tomography @xcite . yet
, attosecond many - body physics is challenging . an exact investigation on classical computers beyond
the single - active - electron approximation becomes prohibitively complex for many....
And you have already written the first three sentences of the full article: the proposed experimental realization of the quantum simulator is based on the extension of an existing experiment . in the experiment @xcite ,
the potential of a tight optical dipole trap is populated with a degenerate fermi gas consisting of @xmath45li atoms in two hyperfine states . by applying a
magnetic - field gradient and varying the trap depth the atoms tunnel out of the trap in a fully controlled way , ending up with a defined number of particles in a determined quantum state ..
Please generate the next two sentences of the article | the experimental dipole trap is described in good approximation by a gaussian - beam potential which results in a quasi 1d confinement with an aspect ratio of about 1:10 .
the beam profile in the longitudinal direction is approximately given by the lorentz potential @xmath46 \quad .\end{aligned}\ ] ] here , @xmath47 is a modulation factor which allows to vary the trap depth in the experiment , see @xcite , @xmath48 is the potential depth , @xmath49 the boltzmann constant , @xmath50 the rayleigh length with a laser wavelength of @xmath51 nm . in the experiment , |
9,885 | Suppose that you have an abstract for a scientific paper: we present three analogues of stern s diatomic sequence . .
And you have already written the first three sentences of the full article: stern s diatomic sequence @xmath0 is a particularly well studied sequence ( see , e.g. , @xcite , @xcite , @xcite and references therein , as well as @xcite ) .
the first section is devoted to showing that this sequence is _
interesting_. in particular , we shall look at the following properties ..
Please generate the next two sentences of the article | * @xmath1 is a bijection between the positive natural numbers and the positive rational numbers , * @xmath2 extends to a continuous strictly increasing function on @xmath3 $ ] known as `` conway s box function '' ( it s inverse is @xmath4 , minkowski s question - mark function ) , * it shares a number of similarities to the fibonacci sequence ; in particular , it has a binet type formula .
.1 in the remaining three sections are devoted to three analogues of stern s sequence : * we replace addition by another binary operation ; in particular , we define @xmath5 where @xmath6 . |
9,886 | Suppose that you have an abstract for a scientific paper: we investigate the core mass distribution ( cmd ) resulting from numerical models of turbulent fragmentation of molecular clouds .
in particular we study its dependence on the sonic root - mean - square mach number @xmath0 .
we analyze simulations with @xmath0 ranging from 1 to 15 to show that , as @xmath0 increases , the number of cores increases as well while their average mass decreases .
this stems from the fact that high - mach number flows produce many and strong shocks on intermediate to small spatial scales , leading to a highly - fragmented density structure .
we also show that the cmd from purely turbulent fragmentation does not follow a single power - law , but it may be described by a function that changes continuously its shape , probably more similar to a log - normal function .
the cmd in supersonic turbulent flows does not have a universal slope , and as consequence , cast some doubt on attempts to directly relate the cmd to a universal initial mass function . '
# 1#1i"13i # 1@xmath1 # 1@xmath2 # 110@xmath1 # 110@xmath2 .
And you have already written the first three sentences of the full article: an isothermal supersonic shock with a mach number @xmath0 creates density enhancements of @xmath3 , where @xmath4 and @xmath5 are the densities of the post- and pre - shocked gas ( e.g. , spitzer 1978 ) . since molecular clouds
are turbulent and supersonic , it can be expected that their internal density structure is , at first order ( i.e. , neglecting gravitational or thermal fragmentation ) , a direct consequence of the fragmentation by the chaotic , supersonic velocity field ( see , e.g. , the reviews by vzquez - semadeni et al . 2000 ; mac low & klessen 2004 ; scalo and elmegreen 2004 and references therein ) , a process which has been called _ turbulent fragmentation_. thus , it is reasonable to expect that supersonic turbulence plays a crucial role in determining the mass distribution of dense cores . in fact , the gravoturbulent scenario of star formation suggests that the cores are formed by compressible turbulent motions inside molecular clouds and that some of those cores may become gravitationally unstable and form stars , while others will redisperse in the ambient medium ( sasao 1973 ; hunter & fleck 1982 ; elmegreen 1993 ; ballesteros - paredes , vzquez - semadeni & scalo 1999 ; klessen et .
al . 2000 ; padoan et al . 2001 ; padoan & nordlund 2002 , hereafter pn02 ) ..
Please generate the next two sentences of the article | on the other hand , the mass distribution of young stars follows a well - known distribution called the initial mass function ( imf ) . for stellar masses
@xmath6 it shows a power - law behavior @xmath7 , with slope @xmath8 ( salpeter 1955 ; scalo 1998 ; kroupa 2002 ; chabrier 2003 ) . |
9,887 | Suppose that you have an abstract for a scientific paper: we present the first detections of the 3@xmath0 m water ice and 3.4@xmath0 m amorphous hydrocarbon ( hac ) absorption features in @xmath1@xmath22 ulirgs .
these are based on deep rest - frame 28@xmath0 m _ spitzer _ irs spectra of 11 sources selected for their appreciable silicate absorption .
the hac - to - silicate ratio for our @xmath1@xmath22 sources is typically higher by a factor of 25 than that observed in the milky way . this hac
` excess ' suggests compact nuclei with steep temperature gradients as opposed to predominantly host obscuration . beside the above molecular absorption features , we detect the 3.3@xmath0 m pah emission feature in one of our sources with three more individual spectra showing evidence for it .
stacking analysis suggests that water ice , hydrocarbons , and pah are likely present in the bulk of this sample even when not individually detected .
the most unexpected result of our study is the lack of clear detections of the 4.67@xmath0 m co gas absorption feature .
only three of the sources show tentative signs of this feature and at significantly lower levels than has been observed in local ulirgs .
overall , we find that the closest local analogs to our sources , in terms of 34@xmath0 m color , hac - to - silicate and ice - to - silicate ratios , as well as low pah equivalent widths are sources dominated by deeply obscured nuclei .
such sources form only a small fraction of ulirgs locally and are commonly believed to be dominated by buried agn .
our sample suggests that , in absolute number , such buried agn are at least an order of magnitude more common at @xmath1@xmath22 than today .
the presence of pah suggests that significant levels of star - formation are present even if the obscured agn typically dominate the power budget . .
And you have already written the first three sentences of the full article: @xmath3one of the most exciting recent discoveries in astronomy is the strong evolution and co - evolution of both the star - formation rate density , and black hole number density from @xmath1@xmath213 to today ( see e.g. * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | particularly interesting are composite or transition objects where quasars co - exist with powerful starbursts ( see e.g. * ? ? ?
* ; * ? ? ? |
9,888 | Suppose that you have an abstract for a scientific paper: this paper presents a new approach to studying galactic structures .
they are considered as the low - frequency normal modes in a disc of orbits precessing at different angular speeds .
such a concept is an adequate alternative to the commonly used approach of treating the disc as a set of individual stars rotating at near - circular orbits around the centre .
the problem of determining the normal modes is reduced to a simple integral equation in the form of the classical eigen - value problem , where the eigen - value is directly equal to the pattern speed of the mode , @xmath0 .
an examination of the general properties of the basic integral equation shows that two types of solutions exist , bar - like and spiral .
the numerical solutions of both types are obtained .
the characteristic pattern speeds are of the order of the mean orbit precession speed , although for the bar - modes @xmath0 can markedly exceed the maximum precessing speed of orbits .
it is shown that the bar - mode grows due to the immediate action of its gravitational field on the stars at the resonance regions .
as for the spiral mode , its excitation is probably due to the inner lindblad resonance that can promote mode growth .
[ firstpage ] keywords : galaxies : structure . .
And you have already written the first three sentences of the full article: a disc galaxy is primarily a set of stars which rotate around the centre at near - circular orbits at the angular velocity @xmath1 .
the observed spiral and bar - like structures are customarily treated as perturbations in such a differentially rotating disc .
thus , one might expect that the typical pattern speeds of these structures , @xmath0 , should be of the order of some average star angular velocity , @xmath2 . in reality.
Please generate the next two sentences of the article | , however , the pattern speeds @xmath0 are of the order of the characteristic precession speed of star orbits , @xmath3 , which is only a small fraction of @xmath2 . recall that @xmath4 for near - circular orbits , where @xmath5 is the epicyclic frequency . according to lynden - bell ( 1979 ) , if stars involved in the formation of the structures satisfy the inequality @xmath6 then each star orbit as a whole , but not the individual stars , participates in the perturbations .
consequently , for studying such structures , it is more reasonable to use the model of the disc of star orbits precessing with different speeds than the commonly used concept of the differentially rotating disc of individual stars . |
9,889 | Suppose that you have an abstract for a scientific paper: we will discuss the relevant conditions to observe a critical tunneling current [ new j. phys .
10 , 045018 ( 2008 ) ] in electron - double layer systems at a total filling factor of one and find they are related to the effective layer separation and the temperature .
our studies suggest that the intensity of the critical tunneling behavior is also directly linked to the area of the sample . .
And you have already written the first three sentences of the full article: under large perpendicular magnetic fields @xmath0 the motion of charged carriers in two - dimensional electron systems ( 2des ) is confined to small cyclotron orbitals .
this confinement suppresses the kinetic energy of the electrons but on the other hand amplifies their coulomb interactions . in single layers
these coulomb correlations can lead to the emergence of fractional quantum hall states ..
Please generate the next two sentences of the article | two individual but closely - spaced 2des may also exhibit a correlated state , however , the underlying physics is now also influenced by the coulomb interactions between the two systems . when the electron densities @xmath1 in both layers are identical and the individual filling factors @xmath2 are close to 1/2 ( i.e. , @xmath3 ) , the system may spontaneously develop interlayer phase coherence , provided the distance @xmath4 between the layers is sufficiently small .
this led to the prediction of josephson - type phenomena in bilayer systems @xcite nearly 20 years ago . |
9,890 | Suppose that you have an abstract for a scientific paper: an independent result for the two loop fermionic contributions to the muon lifetime in the standard model is obtained .
deviations are found with respect to @xcite , which result in a shift of the @xmath0 boson mass by approximately @xmath1 mev over the range of higgs boson masses from 100 gev to 1 tev .
supplied with the bosonic contributions from @xcite , this shift , due to the complete electroweak contributions , varies from @xmath2 mev to @xmath3 mev .
additionally , a new test of the matching procedure defining the fermi constant is presented , which uses fermion masses as infrared regulators . and .
And you have already written the first three sentences of the full article: the muon lifetime is one of the key observables of today s particle physics . not only is it measured very precisely , since the current experimental error is 18 ppm @xcite , but can be described to competing accuracy within the standard model , giving rise to a strong correlation between the masses of the heavy gauge bosons . as a low energy process
, the decay is expected to be governed by an effective interaction involving only the electron , muon and their respective neutrinos .
the dynamics of the system should be corrected mostly by qed , whereas the electroweak interactions determine solely the size of the coupling constant ..
Please generate the next two sentences of the article | the history of the calculation of the electroweak corrections , in which we are interested here , is rather long .
it started in the early eighties with the one loop contributions @xcite . |
9,891 | Suppose that you have an abstract for a scientific paper: we study ` myers effect ' for a bunch of @xmath0-branes with @xmath1 superstrings moving in one direction along the branes .
we show that the ` blown - up ' configuration is the helical @xmath0-brane , which is self - supported from collapse by the axial momentum flow .
the tilting angle of the helix is determined by the number of @xmath0-branes .
the radius of the helix is stabilized to a certain value depending on the number of @xmath0-branes and the momentum carried by @xmath1 superstrings .
this is actually t - dual version of the supertube recently found as the ` blown - up ' configuration of a bunch of @xmath2 superstrings carrying @xmath3-brane charge .
it is found that the helical @xmath0 configuration preserves one quarter of the supersymmetry of @xmath1 vacuum .
# 1#2#3nucl . phys . *
b#1 * ( # 2 ) # 3 # 1#2#3phys .
lett .
* b#1 * ( # 2 ) # 3 # 1#2#3phys . rev . lett.*#1 * ( # 2 ) # 3 # 1#2#3phys . rev
. * d#1 * ( # 2 ) # 3 # 1#2#3ann . phys . *
# 1 * ( # 2 ) # 3 # 1#2#3phys . rep .
* # 1 * ( # 2 ) # 3 # 1#2#3rev .
mod .
phys . *
# 1 * # 1#2#3comm . math .
phys . *
# 1 * ( # 2 ) # 3 # 1#2#3mod .
. lett .
* # 1 * ( # 2 ) # 3 # 1#2#3class .
quantum grav . * # 1 * ( # 2 ) # 3 .
And you have already written the first three sentences of the full article: @xmath4-branes interacting with higher form rr - fields ( @xmath5-form for example ) become @xmath6-branes , which was first suggested by emparan @xcite and nontrivial interactions were explicitly obtained by myers @xcite . in the presence of magnetic rr - fields ,
these interactions are caused by the motion of the branes . with the motion in compact space ( thus carrying angular momentum ) , the higher dimensional brane increases its size .
since the size is bounded in the compact space , the angular momentum is also bounded ..
Please generate the next two sentences of the article | this fact possibly explains the stringy exclusion principle in the dual gravity setup @xcite .
recently mateos and townsend showed that this angular momentum can be given in a different guise @xcite . in some special setup of tubular @xmath7-brane |
9,892 | Suppose that you have an abstract for a scientific paper: spin fluctuation is presumed to be one of the key properties in understanding the microscopic origin of heavy - fermion - like behavior in the class of transition - metal compounds , including liv@xmath0o@xmath1 , y(sc)mn@xmath0 , and ymn@xmath0zn@xmath2 . in this review ,
we demonstrate by our recent study of muon spin rotation / relaxation that the temperature ( @xmath3 ) dependence of the longitudinal spin relaxation rate ( @xmath4 ) in these compounds exhibits a common trend of leveling off to a constant value ( @xmath5 . ) below a characteristic temperature , @xmath6 .
this is in marked contrast to the behavior predicted for normal metals from the korringa relation , @xmath7 , where the spin fluctuation rate ( @xmath8 ) in the pauli paramagnetic state is given as a constant , @xmath9 $ ] [ with @xmath10 being the density of states at the fermi energy ] .
thus , the observed behavior of @xmath11 implies that the spin fluctuation rate becomes linearly dependent on temperature , @xmath12 , suggesting that heavy quasiparticles develop in a manner satisfying @xmath13 at lower temperatures ( @xmath14 determined by the electronic dispersion ) . considering that the theory of spin correlation for intersecting hubbard chains as a model of pyrochlore lattice predicts @xmath12 , our finding strongly indicates the crucial role of @xmath15 bands which preserve the one - dimensional character at low energies due to the geometrical frustration specific to the undistorted pyrochlore lattice . .
And you have already written the first three sentences of the full article: geometrical frustration in electronic degrees of freedom such as spin , charge , and orbit , which is often realized in the stages of highly symmetric crystals , has been one of the major topics in the field of condensed matter physics . in particular , the heavy fermion ( hf ) behavior in y@xmath16sc@xmath17mn@xmath0 [ y(sc)mn@xmath0]@xcite and liv@xmath0o@xmath1 @xcite has attracted broad interest , where such a local electronic correlation specific to the highly symmetric pyrochlore structure may be of direct relevance to the formation of the heavy quasiparticle ( qp ) state .
however , despite decades of studies , the microscopic mechanism by which the local correlation is transformed into the heavy qp mass of itinerant @xmath19-electrons in these compounds still remains controversial . in general , the development of heavy qps accompanies narrowing of the effective band width ( @xmath20 ) or an increase in the density of states ( dos ) at the fermi energy [ @xmath10 ] .
it is thus expected from a naive consideration based on heisenberg s uncertainty principle that the hf behavior should manifest itself in the spin dynamics as reduction of the spin fluctuation rate ( @xmath8 ) because these quantities are mutually linked by the following relation : @xmath22 since the effective qp mass is directly connected to the dos via the relation @xmath23^{2/3}$ ] for a three - dimensional ( 3d ) fermi gas , studies on the spin fluctuation with particular emphasis on relatively low energies should provide valuable information on the mechanism of heavy qp formation . as a probe of spin fluctuation , muon spin rotation ( @xmath24sr ) has a unique frequency window with high sensitivity for @xmath25 s@xmath26 , filling the gap between those covered by nuclear magnetic resonance ( nmr ) and neutron scattering ..
Please generate the next two sentences of the article | this provides promising perspectives for the @xmath24sr study of @xmath19-electron hf - like compounds . here
, we establish that the longitudinal spin relaxation rate ( @xmath4 ) in the above - mentioned compounds exhibits a common feature that it asymptotically becomes independent of temperature upon cooling below a crossover temperature of @xmath27@xmath28 k. this , within the framework of fermionic qps , means that the spin fluctuation rate becomes linearly dependent on temperature , @xmath12 , which is in marked contrast to ordinary metals , where @xmath8 is independent of @xmath3 as determined by the dos at the fermi level . |
9,893 | Suppose that you have an abstract for a scientific paper: remarkable research activities and major advances have been occurred over the past decade in multiuser multiple - input multiple - output ( mu - mimo ) systems . several transmission technologies and precoding techniques
have been developed in order to exploit the spatial dimension so that simultaneous transmission of independent data streams reuse the same radio resources .
the achievable performance of such techniques heavily depends on the channel characteristics of the selected users , the amount of channel knowledge , and how efficiently interference is mitigated . in systems where the total number of receivers is larger than the number of total transmit antennas , user selection becomes a key approach to benefit from multiuser diversity and achieve full multiplexing gain .
the overall performance of mu - mimo systems is a complex joint multi - objective optimization problem since many variables and parameters have to be optimized , including the number of users , the number of antennas , spatial signaling , rate and power allocation , and transmission technique .
the objective of this literature survey is to provide a comprehensive overview of the various methodologies used to approach the aforementioned joint optimization task in the downlink of mu - mimo communication systems .
downlink transmission , multi - user mimo , precoding , resource allocation , spatial multiplexing , user scheduling . .
And you have already written the first three sentences of the full article: wireless systems require fundamental and crisp understanding of design principles and control mechanisms to efficiently manage network resources .
resource allocation policies lie at the heart of wireless communication networks , since they aim at guaranteeing the required quality of service ( qos ) at the user level , while ensuring efficient and optimized operation at the network level to maximize operators revenue .
resource allocation management in wireless communications may include a wide spectrum of network functionalities , such as scheduling , transmission rate control , power control , bandwidth reservation , call admission control , transmitter assignment , and handover @xcite . in this survey ,.
Please generate the next two sentences of the article | a resource allocation policy is defined by the following components : _ i _ ) a multiple access technique and a scheduling component that distributes resources among users subject to individual qos requirements ; _ ii _ ) a signaling strategy that allows simultaneous transmission of independent data streams to the scheduled users ; and _ iii _ ) rate allocation and power control that guarantee qos and harness potential interference .
[ fig : mu - mimo - layered - tasks ] illustrates these components and the interconnection between them . |
9,894 | Suppose that you have an abstract for a scientific paper: we present the results of a search for variable stars in the faint sparse globular cluster e3 . we have found two variable stars : an sx phe variable ( v1 ) and a w uma eclipsing binary ( v2 ) .
we have applied period - luminosity and period - color - luminosity relations to the variables to obtain their distance moduli .
v1 seems to be a blue straggler belonging to e3 , based on its distance modulus and location on the cmd .
v2 is probably located behind the cluster , in the milky way halo .
we also present @xmath0 and @xmath1 color magnitude diagrams of e3 . .
And you have already written the first three sentences of the full article: we present the results of a search for variable stars in the faint sparse globular cluster e3 , located at @xmath2 , @xmath3 .
the cluster was discovered on the eso b schmidt survey of the southern sky by lauberts ( 1976 ) .
the first @xmath4 photometry of the cluster was presented by van den bergh , demers & kunkel ( 1980 ) ..
Please generate the next two sentences of the article | numerous candidates for blue stragglers were identified .
the photoelectric photometry of frogel & twarog ( 1983 ) confirmed this finding . a subsequent study by hesser et al . |
9,895 | Suppose that you have an abstract for a scientific paper: we present a measurement of the microlensing optical depth toward the galactic bulge based on 4 years of the ogle - ii survey .
we consider only bright sources in the extended red clump giant ( rcg ) region of the color - magnitude diagram , in 20 bulge fields covering @xmath0 deg@xmath1 between @xmath2 and @xmath3 .
using a sample of 32 events we find @xmath4 at @xmath5 .
taking into account the measured gradient along the galactic latitude @xmath6 , @xmath7\times 10^{-6}$ ] , this value is consistent with previous measurements using rcg sources and recent theoretical predictions .
we determine the microlensing parameters and select events using a model light curve that allows for flux blending .
photometric quality delivered by difference image analysis ( dia ) combined with the 1.3 median seeing of the ogle - ii images are sufficient to constrain and reject the majority of strong blends .
we find that @xmath8% of the ogle - ii events which appear to have rcg sources are actually due to much fainter stars blended with a bright companion .
we show explicitly that model fits without blending result in similar @xmath9 estimates through partial cancellation of contributions from higher detection efficiency , underestimated time - scales and larger number of selected events . the near cancellation of the optical depth bias and the fact that microlensing event selection based on models without blending discriminates against blends have been utilized by previous analyses based on rcg sources .
the latter approach , however , leads to biased time - scale distributions and event rates . consequently
, microlensing studies should carefully consider source confusion effects even for bright stars . .
And you have already written the first three sentences of the full article: following the suggestion of @xcite and @xcite several teams have carried out microlensing surveys toward the galactic bulge ( gb ) . to date , well over @xmath10 microlensing events in the gb have been detected by those groups : ogle ( @xcite ) , moa ( @xcite ) , macho ( @xcite ) and eros ( @xcite ) .
thousands of detections are expected in the upcoming years from moa and ogle - iii .
it is now well understood that these observations are useful for studying the structure , kinematics and dynamics of the galaxy , and the stellar mass function , as the event rate and time - scale distributions are related to the masses and velocities of lens objects ..
Please generate the next two sentences of the article | the magnification of a microlensing event is described by ( @xcite ) @xmath11 where @xmath12 is the projected separation of the source and lens in units of the einstein radius @xmath13 which is given by @xmath14 where @xmath15 is the lens mass , @xmath16 is the normalized lens distance and @xmath17 and @xmath18 are the observer - lens and the observer - source distances .
the time variation of @xmath19 is @xmath20 where @xmath21 , @xmath22 , @xmath23 and @xmath24 are , respectively , the minimum impact parameter in units of @xmath13 , the time of maximum magnification , the event time - scale and the transverse velocity of the lens relative to the line of sight toward the source star . from light curve alone , one can determine the values of @xmath21 , @xmath22 and @xmath25 , but not the values of @xmath15 , @xmath26 or @xmath24 . |
9,896 | Suppose that you have an abstract for a scientific paper: we investigate the excited states of the quasi - one - dimensional quantum antiferromagnets on hexagonal lattices , including the longitudinal modes based on the magnon - density waves .
a model hamiltonian with a uniaxial single - ion anisotropy is first studied by a spin - wave theory based on the one - boson method ; the ground state thus obtained is employed for the study of the longitudinal modes .
the full energy spectra of both the transverse modes ( i.e. , magnons ) and the longitudinal modes are obtained as functions of the nearest - neighbor coupling and the anisotropy constants .
we have found two longitudinal modes due to the non - collinear nature of the triangular antiferromagnetic order , similar to that of the phenomenological field theory approach by affleck .
the excitation energy gaps due to the anisotropy and the energy gaps of the longitudinal modes without anisotropy are then investigated .
we then compare our results for the longitudinal energy gaps at the magnetic wavevectors with the experimental results for several antiferromagnetic compounds with both integer and non - integer spin quantum numbers , and we find good agreement after the higher - order contributions are included in our calculations .
pacs numbers : : 75.10.jm , 75.30.ds , 75.50.ee . .
And you have already written the first three sentences of the full article: the excitations of the quasi - one - dimensional ( 1d ) heisenberg antiferromagnets systems have been studied extensively since haldane predicted an energy gap in the excitation spectra of the isotropic _ integer_-spin heisenberg chains in 1983 @xcite .
now it is well established that there is an energy gap separating the singlet ground state from the triplet lowest - energy - excitation states for the _ integer_-spin heisenberg chains , contrast to the gapless excitation states of the _ half - odd - integer_-spin heisenberg systems @xcite .
this theoretical prediction has been confirmed by buyers _.
Please generate the next two sentences of the article | et al _ @xcite in the inelastic - neutron - scattering experiments on the quasi-1d antiferromangetic compound csnicl@xmath0 .
some subsequent experimental investigations @xcite and numerical calculations @xcite also support haldane s prediction . at very low temperature , |
9,897 | Suppose that you have an abstract for a scientific paper: we determine and examine the star - formation rates of 50 well known , local blue compact dwarf ( bcd ) galaxies based on their 1.4ghz and 60@xmath0 m luminosities .
we find that in cases for which both radio and far - infrared luminosities are available , the resulting star - formation rates agree extremely well with one another .
we determine that the star - formation rates of the bcd galaxies in our sample span nearly five orders of magnitude , from approximately a few times 10@xmath1 to several times 10@xmath2m@xmath3yr@xmath4 , with a median sfr of about 0.3@xmath5m@xmath3yr@xmath4 .
we discuss trends of metallicity ( primarily oxygen abundance ) with star - formation rate , and explore the connections between sfr and galaxy mass estimates . .
And you have already written the first three sentences of the full article: blue compact dwarf ( bcd ) galaxies provide evidence that isolated , small , low - metallicity galaxies may experience vigorous star formation in the present epoch , challenging our current understanding of galaxy formation .
the very nature of bcds remains puzzling in spite of thirty years of research since they were first recognized as an interesting class of galaxy @xcite .
for instance , it is still debated whether some primeval " bcds are perhaps in the process of undergoing their very first starburst , or whether bcds undergo several episodic starbursts separated by long quiescent intervals , what triggers the star formation in bcds , and whether starburst - induced supernova - driven winds can cause the transformation of bcds into one of the other known types of dwarf galaxy ( * ? ? ? * for a recent review ) ..
Please generate the next two sentences of the article | while star - formation rates ( sfrs ) are central to discussions of the evolution of bcds , there are surprisingly few quantitative sfrs for bcds available in the literature .
the earliest and most quoted quantitative sfrs are based on direct measures of the ultraviolet luminosity of massive stars in formation . |
9,898 | Suppose that you have an abstract for a scientific paper: a summary is given on the experimental bounds for the couplings and masses of scalar and vector leptoquarks associated to the first fermion generation .
we investigate to which extent an interpretation of the recently reported excess of events in the large @xmath0 and @xmath1 range at hera in terms of single leptoquark production is compatible with other experimental results .
desy 97032 + hep - ph/9703287 + march 8 , 1997 + z. phys .
* c * ( 1997 ) , in print .
* on the expectations for leptoquarks * + + johannes blmlein + + _ platanenallee 6 , d15735 zeuthen , germany
_ + .
And you have already written the first three sentences of the full article: one of the remarkable properties of the @xmath2 standard model is the cancellation of the triangle anomalies , which is implied by the relation @xmath3 between the electromagnetic and the left and righthanded weak charges of the leptons and quarks for each fermion family .
this relation is of fundamental importance , because it renders the standard model renormalizable .
although not being enforced by every possible scenario , it might be a dynamical consequence of an as yet unknow underlying theory . in many extensions of the standard model new bosons , the leptoquarks @xmath4 , which carry both lepton and baryon number , are predicted ..
Please generate the next two sentences of the article | this applies both to grand unified theories @xcite as well as models based on compositeness @xcite or technicolor @xcite .
whereas in grand unified theories leptoquarks emerge as gauge bosons with masses in the range of @xmath5 and couplings which do not conserve baryon ( b ) and lepton ( l ) number , other approaches contain also leptoquarks with b- and l - conserving couplings . |
9,899 | Suppose that you have an abstract for a scientific paper: since the discovery of the first double neutron star ( dns ) system in 1975 by hulse and taylor , there are currently 8 confirmed dns in our galaxy . for every system , the masses of both neutron stars , the orbital semi - major axis and eccentricity are measured , and proper motion is known for half of the systems . using the orbital parameters and kinematic information , if available , as constraints for _ all system _ _ , we investigate the immediate progenitor mass of the second - born neutron star and the magnitude of the supernova kick it received at birth , with the primary goal to understand the core collapse mechanism leading to neutron star formation .
compared to earlier studies , we use a novel method to address the uncertainty related to the unknown radial velocity of the observed systems . for psr b1534 + 12 and psr b1913 + 16 ,
the kick magnitudes are 150 - 270 km / s and 190 - 450 km / s ( with 95% confidence ) respectively , and the progenitor masses of the 2nd born neutron stars are 1.3 - 3.4 m@xmath0 and 1.4 - 5.0 m@xmath0 ( 95% ) , respectively .
these suggest that the 2nd born neutron star was formed by an iron core collapse supernova in both systems . for psr j0737 - 3039 , on the other hand ,
the kick magnitude is only 5 - 120 km / s ( 95% ) , and the progenitor mass of the 2nd born neutron star is 1.3 - 1.9 m@xmath0 ( 95% ) . because of the relatively low progenitor mass and kick magnitude , the formation of the 2nd born neutron star in psr j0737 - 3039 is potentially connected to an electron capture supernova of a massive @xmath1 white dwarf . for
the remaining 5 galactic dns , the kick magnitude ranges from several tens to several hundreds of km / s , and the progenitor mass of the 2nd formed neutron star can be as low as @xmath21.5 m@xmath0 , or as high as @xmath28 m@xmath0 .
therefore in these systems , it is not clear which type of supernova is more likely to form the 2nd neutron star . _ _ _ .
And you have already written the first three sentences of the full article: over the years , computation modeling and hydrodynamic calculations of supernova explosions due to core - collapse of massive stars have improved our theoretical understanding of how compact objects form . at present ,
two types of supernovae are actively discussed in the literature : ( i ) after iron is synthesized within a massive star , the core completes its final nuclear burning state .
it then becomes degenerate and keeps growing in mass due to silicon shell burning outside the core ..
Please generate the next two sentences of the article | eventually , it crosses the chandrasekhar mass limit and ensues collapse .
when the core reaches nuclear density , it bounces back and explodes the star as a supernova . |
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