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5,400 | Suppose that you have an abstract for a scientific paper: the transparent sun is modeled as a spherically symmetric and centrally condensed gravitational lens using recent standard solar model ( ssm ) data .
the sun s minimum focal length is computed to a refined accuracy of 23.5 @xmath0 au , just beyond the orbit of uranus .
the sun creates a single image of a distant point source visible to observers inside this minimum focal length and to observers sufficiently removed from the line connecting the source through the sun s center .
regions of space are mapped where three images of a distant point source are created , along with their associated magnifications .
solar caustics , critical curves , and einstein rings are computed and discussed .
extremely high gravitational lens magnifications exist for observers situated so that an angularly small , unlensed source appears near a three - image caustic .
types of radiations that might undergo significant solar lens magnifications as they can traverse the core of the sun , including neutrinos and gravitational radiation , are discussed . .
And you have already written the first three sentences of the full article: our sun is known to act as a gravitational lens .
the angular shift of the apparent position of a star located behind the sun was first observed during the solar eclipse of 1919 @xcite , in conformity with the predictions of general relativity @xcite .
many years later , einstein ( 1936 ) discussed the lens like action of the sun s gravitational field more generally ..
Please generate the next two sentences of the article | the influence of that discussion has caused the ring seen by the observer during perfect alignment of the source , lens and the observer to be called the einstein ring around a point lens .
for an opaque lens , the result of exterior focusing of the parallel light rays incident with an impact parameter @xmath1 on the lens plane is a deflection @xmath2 . |
5,401 | Suppose that you have an abstract for a scientific paper: be it for taking advantage of stock undervaluation or in order to distribute part of their profits to shareholders , firms may buy back their own shares .
one of the way they proceed is by including accelerated share repurchases ( asr ) as part of their repurchase programs . in this article
, we study the pricing and optimal execution strategy of an asr contract with fixed notional .
in such a contract the firm pays a fixed notional @xmath0 to the bank and receives , in exchange , a number of shares corresponding to the ratio between @xmath0 and the average stock price over the purchase period , the duration of this period being decided upon by the bank . from a mathematical point of view , the problem is related to both optimal execution and exotic option pricing .
* key words : * optimal execution , asr contracts , optimal stopping , stochastic optimal control , utility indifference pricing . .
And you have already written the first three sentences of the full article: the traditional way for a firm to repurchase its own shares is through open - market repurchase programs ( omr ) .
however , as reported in @xcite , after they have announced they intend to buy back shares , a substantial number of firms do not commit to their initial plan .
unexpected shocks on prices or on the liquidity of the stock may indeed provide incentives to slow down , postpone , or even cancel repurchase programs . in order to make a credible commitment to buy back shares , an increasing number of firms enter accelerated share repurchase contracts with investment banks ..
Please generate the next two sentences of the article | accelerated share repurchase contracts are of several kinds and we traditionally distinguish between asr with fixed number of shares and fixed notional asr . in the case of an asr with fixed number of shares ( @xmath1 ) ,
the contract is the following : 1 . at time @xmath2 |
5,402 | Suppose that you have an abstract for a scientific paper: we calculate the resistance between two arbitrary grid points of several infinite lattice structures of resistors by using lattice green s functions . the resistance for @xmath0 dimensional hypercubic , rectangular , triangular and honeycomb lattices of resistors
is discussed in detail .
we give recurrence formulas for the resistance between arbitrary lattice points of the square lattice . for large separation between nodes
we calculate the asymptotic form of the resistance for a square lattice and the finite limiting value of the resistance for a simple cubic lattice .
we point out the relation between the resistance of the lattice and the van hove singularity of the tight - binding hamiltonian .
our green s function method can be applied in a straightforward manner to other types of lattice structures and can be useful didactically for introducing many concepts used in condensed matter physics . .
And you have already written the first three sentences of the full article: it is an old question to find the resistance between two adjacent grid points of an infinite square lattice in which all the edges represent identical resistances @xmath1 .
it is well known that the result is @xmath2 , and an elegant and elementary solution of the problem is given by aitchison @xcite .
the electric - circuit theory is discussed in detail in a classic text by van der pol and bremmer@xcite and they derive the resistance between nearby points on the square lattice . in doyle s and snells@xcite.
Please generate the next two sentences of the article | book the connection between random walks and electric networks is presented , including many interesting results and useful references .
recently venezian @xcite and atkinson et . |
5,403 | Suppose that you have an abstract for a scientific paper: the techniques of power recycling and signal recycling have proven as key concepts to increase the sensitivity of large - scale gravitational wave detectors by independent resonant enhancement of light power and signal sidebands within the interferometer .
developing the latter concept further , _ twin signal recycling _ was proposed as an alternative to conventional detuned signal recycling .
twin signal recycling features the narrow - band sensitivity gain of conventional detuned signal recycling but furthermore facilitates the injection of squeezed states of light , increases the detector sensitivity over a wide frequency band and requires a less complex detection scheme for optimal signal readout .
these benefits come at the expense of an additional recycling mirror , thus increasing the number of degrees of freedom in the interferometer which need to be controlled . in this article
we describe the development of a length sensing and control scheme and its successful application to a tabletop - scale power recycled michelson interferometer with twin signal recycling .
we were able to lock the interferometer in all relevant longitudinal degrees of freedom , enabling the long - term stable operation of the experiment .
we thus laid the foundation for further investigations of this interferometer topology to evaluate its viability for the application in gravitational wave detectors .
99 b. willke for the geo collaboration , `` the geo - hf project , '' class .
quantum grav .
* 23 , * s207s214 ( 2006 ) .
g. m. harry for the ligo scientific collaborations , `` advanced ligo : the next generation of gravitational wave detectors , '' class
. quantum grav .
* 27 , * 084006 ( 2010 )
. the virgo collaboration , `` status of the virgo project , '' class .
quantum grav .
* 28 , * 114002 ( 2011 ) .
k. somiya for the kagra collaboration , `` detector configuration of kagra the japanese cryogenic gravitational - wave detector , '' class .
quantum grav .
....
And you have already written the first three sentences of the full article: the international network of large - scale interferometric gravitational wave ( gw ) detectors is currently undergoing an extensive technological upgrade towards what is commonly referred to as the `` second generation '' of gw detectors . upon completion , these second generation observatories , namely geo - hf @xcite , advanced ligo @xcite and advanced virgo @xcite , complemented by the new observatory kagra @xcite , will reach unprecedented sensitivities to gw - induced strain .
this sensitivity improvement constitutes a major leap towards reaching the long - standing goal of the first direct measurement of gws . besides power recycling ( pr ) , which was already implemented in the first generation ligo and virgo interferometers , signal recycling
@xcite ( sr ) has been adopted for the optical layouts of all second generation detectors ..
Please generate the next two sentences of the article | dual recycling , i.e. the combination of pr and sr , has already been successfully implemented and operated in the geo600 detector @xcite .
furthermore , the injection of squeezed vacuum a technique proposed by caves to improve the quantum noise limited sensitivity of gw detectors @xcite will be employed to enhance the performance of geo - hf as well as the advanced ligo hanford observatory . |
5,404 | Suppose that you have an abstract for a scientific paper: we present a catalogue of h band spectra for 85 stars of approximately solar abundance observed at a resolving power of 3000 with the kpno mayall 4 m fts .
the atlas covers spectral types o7m5 and luminosity classes i - v as defined on the mk system .
we identify both atomic and molecular indices and line ratios which are temperature and luminosity sensitive allowing spectral classification to be carried out in the h band .
the line ratios permit spectral classification in the presence of continuum excess emission , which is commonly found in pre main sequence and evolved stars .
we demonstrate that with spectra of @xmath0 obtained at @xmath1 it is possible to derive spectral types within @xmath2 subclasses for late type stars .
these data are available electronically through the astronomical data center in addition to being served on the world wide web .
# 1#2#3#4#5#6#7 to = -0.2 truein .
And you have already written the first three sentences of the full article: with the recent development of large format infrared array detectors , high quality photometric surveys are routinely conducted at wavelengths between 12.5 @xmath3 m . soon the completion of the 2 micron all sky survey ( 2mass ; skrutskie 1997 ) and denis ( epchtein et al .
1997 ) will provide comprehensive catalogues of near infrared sources with detection limits sensitive to a wide variety of stellar and non stellar objects .
infrared spectra will be required for appropriate identification of many of these sources , and for further study of their astrophysical properties ..
Please generate the next two sentences of the article | the pioneering study of johnson and mendez ( 1970 ) was the first to explore the spectra of a large sample of normal stars in the near infrared .
however many years passed before improvements in instrumentation made possible similar observations of large numbers of targets of astrophysical interest . |
5,405 | Suppose that you have an abstract for a scientific paper: deep hst broad - band images taken with acs and wfpc2 of the giant ( @xmath0 au diameter ) dark silhouette proplyd 114 - 426 in the orion nebula show that this system is tilted , asymmetric , warped and photoevaporated .
the exquisite angular resolution of acs allows us to map the distribution of dust grains at the northern translucent edge of the disk , dominated by the photoevaporative flow . using the mie theory for standard circumstellar disk grains , we find evidence for a spatial gradient in grain size . the typical dust radius , @xmath1 m ( less than what reported by previous studies ) becomes smaller as the distance from the disk center increases , consistent with the expectations for the dynamic of dust entrained in a gaseous photoevaporative wind .
our analysis of the disk morphology and location within the nebula indicates that this system is photoevaporated by the diffuse radiation field of the orion nebula , while being shielded from the radiation coming directly from the central trapezium stars .
we estimate the mass - loss rate from the disk surface and the time - scale for total disk dissipation , which turns out to be of the order of @xmath2yr . such a short time , of the order of 1/100 of the cluster age ,
indicates that this system is seen on the verge of destruction .
this is compatible with the exceptional nature of the disk , namely its combination of huge size and low mass .
finally , we briefly discuss the viability of possible mechanisms that may lead to the peculiar morphology of this system : external uv flux , binary star and past close encounter . .
And you have already written the first three sentences of the full article: early _ hubble space telescope
_ ( hst ) images of circumstellar disks in the orion nebula cluster have provided the first direct evidence that protoplanetary disks in rich young stellar clusters may be photo - evaporated by uv radiation of nearby massive stars @xcite .
the typical signature of photo - evaporation is a bright ionized cusp pointing to the brightest stars of the cluster , @xmath3ori - c in particular ..
Please generate the next two sentences of the article | the cusps always surround a central low - mass star , that may occasionally be encircled by a compact dark disk seen in silhouette against the nebular background , or against the cusp itself .
the most recent atlas of protoplanetary disks ( `` proplyds '' ) in the orion nebula @xcite counts 178 of these comet - shaped sources . |
5,406 | Suppose that you have an abstract for a scientific paper: the band structure of fully hydrogenated si nanosheets and nanotubes are elucidated by the use of an empirical tight - binding model .
the hydrogenated si sheet is a semiconductor with indirect band gap of about @xmath0ev .
the symmetries of the wave functions allow us to explain the origin of the gap .
we predict that , for certain chiralities , hydrogenated si nanotubes represent a new type of semiconductor , one with co - existing direct and indirect gaps of exactly the same magnitude .
this behavior is different from the hamada rule established for non - hydrogenated carbon and silicon nanotubes .
comparison to an ab initio calculation is made . .
And you have already written the first three sentences of the full article: graphene exhibits electronic properties that conventional metals do not show , e.g. , charge carriers with zero effective mass , anomalous quantum hall effect , and a minimum conductivity when carrier concentrations tend to zero @xcite .
the unconventional electronic properties of graphene occur due to its linear energy dispersion in the vicinity of the dirac point and two - dimensional structure @xcite .
recent theoretical studies show , however , that a linear energy dispersion relation is not unique to graphene @xcite ..
Please generate the next two sentences of the article | for instance , a flat two - dimensional silicon ( si ) sheet with a honeycomb lattice ( silicene ) exhibits a linear energy dispersion too @xcite .
even buckling of the si honeycomb lattice ( si tends to form @xmath1 bonds rather than @xmath2 bonds ) does not remove the linearity in the energy dispersion relation nor does it open an energy gap @xcite . |
5,407 | Suppose that you have an abstract for a scientific paper: recent work has indicated that ghost imaging may have applications in standoff sensing . however , most theoretical work has addressed transmission - based ghost imaging . to be a viable remote - sensing system
, the ghost imager needs to image rough - surfaced targets in reflection through long , turbulent optical paths .
we develop , within a gaussian - state framework , expressions for the spatial resolution , image contrast , and signal - to - noise ratio of such a system .
we consider rough - surfaced targets that create fully developed speckle in their returns , and kolmogorov - spectrum turbulence that is uniformly distributed along all propagation paths .
we address both classical and nonclassical optical sources , as well as a computational ghost imager . .
And you have already written the first three sentences of the full article: ghost imaging is a transverse active - imaging technique that exploits the correlation between two light beams to image a target without spatially - resolving measurements of the light beam that has undergone target interaction .
the two beams are the signal , which interacts with the target and then is measured by a single - pixel bucket detector , and the reference , which is directly measured by a high spatial - resolution detector . an intensity cross - correlation between the signal beam that encounters the target and
the reference beam that impinges on the high spatial - resolution detector imparts target information the ghost image to the cross correlation between the photocurrents obtained from the two detectors , information that is unavailable from either photocurrent alone ..
Please generate the next two sentences of the article | most ghost - imaging experiments and related theory deal with the transmissive case , in which the bucket detector is placed behind the target , and we image the target s intensity - transmission profile . in the first ghost imaging experiment , the signal and reference beams were the quantum - mechanically entangled outputs from a spontaneous parametric downconverter ( spdc ) @xcite , which afforded them a phase - sensitive cross correlation stronger than permitted by classical physics @xcite .
the system was run at low flux , in which the spdc s post - selected output state , within the photodetectors response time , could be taken to be a biphoton ; the ghost image was then formed by counting coincidences between the bucket and high spatial - resolution detections instead of a photocurrent cross correlation . |
5,408 | Suppose that you have an abstract for a scientific paper: we present a real - time diagrammatic formalism to study adiabatic pumping in chains of tunnel - coupled metallic islands .
this approach is based on an expansion to linear order in the frequency of the time - dependent parameters and on a systematic perturbation expansion in the tunnel - coupling strength .
we apply our formalism to single - island and double - island systems . in the single - island setup , we find that the first - order contribution in the tunnel - coupling strength is purely due to the renormalization of the charging - energy gap . in the double - island system
, we investigate the transition between weak and strong pumping . .
And you have already written the first three sentences of the full article: the most common method to drive a current through a conductor is by applying a voltage . in nanostructures , due to the ease with
which parameters can be tuned , another possibility opens up : _ pumping .
_ in an electron pump a dc current can be generated in a nanoscale conductor , even at zero - bias voltage , by periodically changing some of its properties in time ..
Please generate the next two sentences of the article | if the time dependence of the parameters is slow compared to the internal time scales of the system , such as the dwell time of carriers , pumping is adiabatic . in this case
, the pumped charge does not depend on the detailed time evolution of the pumping cycle but only on its area . |
5,409 | Suppose that you have an abstract for a scientific paper: unless there is evidence for fractal scaling with a single exponent over distances @xmath0 then the widely accepted notion of scale invariance of the correlation integral for @xmath1 must be questioned .
the attempt to extract a scaling exponent @xmath2 from the correlation integral @xmath3 by plotting @xmath4 vs. @xmath5 is unreliable unless the underlying point set is approximately monofractal .
the extraction of a spectrum of generalized dimensions @xmath6 from a plot of the correlation integral generating function @xmath7 by a similar procedure is probably an indication that @xmath7 does not scale at all .
we explain these assertions after defining the term multifractal , mutually
inconsistent definitions having been confused together in the cosmology literature .
part of this confusion is traced to a misleading speculation made earlier in the dynamical systems theory literature , while other errors follow from confusing together entirely different definitions of `` multifractal '' from two different schools of thought .
most important are serious errors in data analysis that follow from taking for granted a largest term approximation that is inevitably advertised in the literature on both fractals and dynamical systems theory . .
And you have already written the first three sentences of the full article: knowlege of the three dimensional distribution of matter in the universe at @xmath8 is limited .
we do not know if the matter distribution over scales @xmath9 is homogeneous or isotropic ( background radiation , self consistency of the standard model based on the assumption of a _
stable _ uniform density , etc ..
Please generate the next two sentences of the article | do not provide direct evidence about the distribution of visible matter in the present epoch ) .
for @xmath10 the distribution of visible matter is clearly inhomogeneous , with large voids and clustering , and various analyses have produced results that are equivalent to claiming scale invariance for the correlation integral , that @xmath11 , with one school ( @xcite , @xcite ) reporting that @xmath12 for @xmath13 , whereas the other ( @xcite , @xcite ) reports that @xmath14 for @xmath15 . |
5,410 | Suppose that you have an abstract for a scientific paper: nonspherical perturbation theory has been necessary to understand the meaning of radiation in spacetimes generated through fully nonlinear numerical relativity .
recently , perturbation techniques have been found to be successful for the time evolution of initial data found by nonlinear methods .
anticipating that such an approach will prove useful in a variety of problems , we give here both the practical steps , and a discussion of the underlying theory , for taking numerically generated data on an initial hypersurface as initial value data and extracting data that can be considered to be nonspherical perturbations . .
And you have already written the first three sentences of the full article: the formation of a black hole is , in principle , one of the most efficient mechanisms for generation of gravitational waves .
such sources tie together two major research initiatives .
laser interferometric gravity wave detectors@xcite hold out a promise of the detection of gravitational waves from astrophysical events . to interpret the results of the gravitational wave signals , and to help find signals in the detector noise.
Please generate the next two sentences of the article | , a broad and detailed knowledge will be needed of astrophysical gravitational waveforms .
this is one of the underlying motivations for the `` grand challenge''@xcite in high performance computing , aimed at computing the coalescence of black hole binaries . |
5,411 | Suppose that you have an abstract for a scientific paper: we study two - particle long - range rapidity correlations arising in the early stages of heavy ion collisions in the saturation / color glass condensate framework , assuming for simplicity that one colliding nucleus is much larger than the other .
we calculate the two - gluon production cross section while including all - order saturation effects in the heavy nucleus with the lowest - order rescattering in the lighter nucleus .
we find four types of correlations in the two - gluon production cross section : ( i ) geometric correlations , ( ii ) hbt correlations accompanied by a back - to - back maximum , ( iii ) away - side correlations , and ( iv ) near - side azimuthal correlations which are long - range in rapidity . the geometric correlations ( i ) are due to the fact that nucleons are correlated by simply being confined within the same nucleus and may lead to long - range rapidity correlations for the produced particles without strong azimuthal angle dependence . somewhat surprisingly , long - range rapidity correlations ( iii ) and ( iv ) have exactly the same amplitudes along with azimuthal and rapidity shapes : one centered around @xmath0 with the other one centered around @xmath1 ( here @xmath2 is the azimuthal angle between the two produced gluons ) .
we thus observe that the early - time cgc dynamics in nucleus - nucleus collisions generates azimuthal non - flow correlations which are qualitatively different from jet correlations by being long - range in rapidity .
if strong enough , they have the potential of mimicking the elliptic ( and higher - order even - harmonic ) flow in the di - hadron correlators : one may need to take them into account in the experimental determination of the flow observables . .
And you have already written the first three sentences of the full article: long - range rapidity correlations between pairs of hadrons produced at small azimuthal angles with respect to each other were discovered recently in heavy ion ( @xmath3 ) @xcite , proton proton ( @xmath4 ) @xcite , and proton nucleus ( @xmath5 ) collisions @xcite . due to the particular shape of the corresponding correlation function , with a narrow correlation in the azimuthal angle @xmath2 and a wide correlation in pseudo - rapidity separation @xmath6 , these correlations are often referred to as the `` ridge '' .
there appears to be a consensus in the community that the origin of these long - range rapidity correlations is in the very early - time dynamics immediately following the collision .
a simple causality argument demonstrates that a correlation between two hadrons produced far apart in rapidity may arise only in their common causal past , that is , in the early stages of the collision @xcite ..
Please generate the next two sentences of the article | however , the detailed dynamical origin of these `` ridge '' correlations is not completely clear .
it has been proposed in the literature @xcite that the `` ridge '' correlations may arise in the classical gluon field dynamics of the parton saturation physics / color glass condensate ( cgc ) . |
5,412 | Suppose that you have an abstract for a scientific paper: we study the ultrafast dynamics of surface electromagnetic waves photogenerated on aluminum film perforated with subwavelength holes array by means of transient photomodulation with @xmath0 fs time resolution . we observed a pronounced _ blueshift _ of the resonant transmission band that reveals the important role of plasma attenuation in the dynamics and that is inconsistent with plasmon - polariton mechanism of extraordinary transmission .
the transient photomodulation spectra were successfully modeled within the boltzmann equation approach for the electron - phonon relaxation dynamics , involving non - equilibrium hot electrons and quasi - equilibrium phonons . .
And you have already written the first three sentences of the full article: on a smooth metal - dielectric interface light does not couple to elementary electronic excitations of the metal surfaces because of energy and momentum conservation .
but in a metal film that is perforated with a two - dimensional ( 2d ) periodic array of holes forming a 2d metallo - dielectric photonic crystal , the periodicity promotes zone folding that results in the formation of band structure .
the grating makes it possible for light to couple directly to surface electromagnetic waves by transfering them the reciprocal lattice momentum @xmath1 , where @xmath2 is the grating period @xcite ..
Please generate the next two sentences of the article | indeed , it was recently found@xcite that the optical transmission through hole arrays fabricated on optically thick metallic films is enhanced by orders of magnitude at resonances ; this phenomenon has been dubbed `` extraordinary transmission '' ( eot ) .
the maxima in the zero - order transmission spectrum is alternated by deep minima caused by wood s anomalies formed due to the diffraction grating of the corrugated film . |
5,413 | Suppose that you have an abstract for a scientific paper: astronomical observations have shown that small carbonaceous molecules can persist in interstellar clouds exposed to intense ultraviolet radiation .
current astrochemical models lack quantitative information on photodissociation rates in order to interpret these data .
we here present _
ab initio _ multi - reference configuration - interaction calculations of the vertical excitation energies , transition dipole moments and oscillator strengths for a number of astrophysically relevant molecules : c@xmath0 , c@xmath1 , c@xmath2h , @xmath3 and @xmath4c@xmath0h , @xmath3 and @xmath4c@xmath0h@xmath2 , hc@xmath0h , @xmath3c@xmath1h and @xmath3c@xmath5h .
highly excited states up to the 9th root of each symmetry are computed , and several new states with large oscillator strengths are found below the ionization potentials .
these data are used to calculate upper limits on photodissociation rates in the unattenuated interstellar radiation field by assuming that all absorptions above the dissociation limit lead to dissociation .
molecular data , excited electronic states , oscillator strengths , photodissociation , interstellar molecules 31.15.ar , 31.50.df , 33.15.fm , 33.20 , 33.70.ca , 33.80.gj , 95.30.ky , 98.38.bn , 98.38.-j .
And you have already written the first three sentences of the full article: of the more than 130 different molecules found in interstellar space , an important class is formed by the unsaturated carbonaceous species .
carbohydrides ranging from small molecules such as c@xmath2h @xcite to long chains like c@xmath6h @xcite and hc@xmath7n @xcite have been detected through their millimeter transitions in cold dark clouds like tmc-1 for several decades .
some of these molecules have also been seen in their cyclic form , with c - c@xmath0h@xmath2 as the best - known example @xcite ..
Please generate the next two sentences of the article | even negative ions , in particular c@xmath8h@xmath9 , have now been detected @xcite .
bare carbon chains are likely present as well but do not have a permanent dipole moment and can therefore not be observed through their pure rotational transitions in emission . instead , the smallest members of this family , c@xmath2 and c@xmath0 , have been detected in diffuse interstellar clouds , i.e . , clouds which are not completely opaque to visible and ultraviolet radiation through their electronic absorptions against bright background stars @xcite . |
5,414 | Suppose that you have an abstract for a scientific paper: galaxy mergers have been investigated for decades using smoothed particle hydrodynamics ( sph ) , but recent work highlighting inaccuracies inherent in the traditional sph technique calls into question the reliability of previous studies .
we explore this issue by comparing a suite of gadget-3 sph simulations of idealised ( i.e. , non - cosmological ) isolated discs and galaxy mergers with otherwise identical calculations performed using the moving - mesh code arepo .
when black hole ( bh ) accretion and active galactic nucleus ( agn ) feedback are not included , the star formation histories ( sfhs ) obtained from the two codes agree well . when bhs are included , the code- and resolution - dependent variations in the sfhs are more significant , but the agreement is still good , and the stellar mass formed over the course of a simulation is robust to variations in the numerical method . during a merger ,
the gas morphology and phase structure are initially similar prior to the starburst phase .
however , once a hot gaseous halo has formed from shock heating and agn feedback ( when included ) , the agreement is less good . in particular , during the post - starburst phase , the sph simulations feature more prominent hot gaseous haloes and spurious clumps , whereas with arepo , gas clumps and filaments are less apparent and the hot halo gas can cool more efficiently .
we discuss the origin of these differences and explain why the sph technique yields trustworthy results for some applications ( such as the idealised isolated disc and galaxy merger simulations presented here ) but not others ( e.g. , gas flows onto galaxies in cosmological hydrodynamical simulations ) .
[ firstpage ] hydrodynamics methods : numerical galaxies : interactions galaxies : starburst galaxies : active galaxies : formation . .
And you have already written the first three sentences of the full article: galaxy mergers are a natural and crucial ingredient of the @xmath0cdm hierarchical galaxy formation paradigm .
although the fraction of galaxies undergoing a merger at any given time is relatively small , nearly all galaxies will experience a merger at some point in their histories ( e.g. , * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
particularly significant are ` major ' mergers , which can be transformative . in these cases |
5,415 | Suppose that you have an abstract for a scientific paper: we present smarts consortium optical / ir light curves of sn 2006aj associated with grb 060218 .
we find that this event is broadly similar to two previously observed events sn 1998bw / grb 980425 and sn 2003lw / grb 031203 .
in particular , all of these events are greatly under - luminous in gamma - rays compared to typical long - duration grbs . we find that the observation by _
swift _ of even one such event implies a large enough true event rate to create difficulties in interpreting these events as typical grbs observed off - axis .
thus these events appear to be intrinsically different from and much more common than high - luminosity grbs , which have been observed in large numbers out to a redshift of at least 6.3 .
the existence of a range of intrinsic energies of grbs may present challenges to using grbs as standard candles . .
And you have already written the first three sentences of the full article: while some long - duration gamma - ray bursts ( grbs ) are clearly associated with supernovae ( sne ) , a deeper understanding of the grb / sn connection remains elusive .
the grb / sn link was first confirmed observationally with the detection of the low - reshift grb 980425/sn 1998bw ( @xmath0 ) @xcite .
grb 980425 , however , was not a typical grb ; it was under - luminous in gamma - rays and had no detected optical afterglow ( oag ) ..
Please generate the next two sentences of the article | sne were later associated with typical grbs at cosmological redshifts ( e.g. * ? ? ?
* ; * ? ? ? |
5,416 | Suppose that you have an abstract for a scientific paper: we consider a composite system consisting of coupled particles , and investigate decoherence due to coupling of the center - of - mass degree of freedom with the internal degrees of freedom . for a simple model of two bound particles ,
we show that in general such a decoherence effect exists , and leads to suppression of interference between different paths of the center - of - mass . for the special case of two harmonically - bound particles moving in an external potential in one dimension
, we show that the coupling between the center - of - mass and internal degrees of freedom can be approximated as parametric driving , and that nontrivial coupling depends on the second derivative of the external potential .
we find a partial solution to this parametric driving problem .
for a simple interference experiment , consisting of two wave packets scattering off of a square well , we perform numerical simulations and show a close connection between suppression of interference and entanglement between the center - of - mass and internal degrees of freedom .
we also propose a _ measure of compositeness _ which quantifies the extent to which a composite system can not be approximated as a single , indivisible particle .
we numerically calculate this quantity for our square well example system . .
And you have already written the first three sentences of the full article: though the fundamental components of all physical systems follow the laws of quantum mechanics , the objects in our everyday reality obey newton s laws .
clearly , in composite objects , the quantum interactions of numerous particles somehow conspire to produce a `` whole '' that obeys newtonian physics .
unfortunately , quantum theory does not provide a natural or obvious framework for the derivation of that classical reality , or for indicating the border between quantum and classical behavior . in the early days of quantum theory.
Please generate the next two sentences of the article | the demarcation between quantum and classical behavior was often placed , at least approximately , at the boundary between the microscopic and macroscopic . but this could nt be the ultimate answer , for no object is truly macroscopic in the sense that it is a single particle of macroscopic dimension and weight . instead , to call something macroscopic is to approximate it by ignoring the internal states of its microscopic components , thereby essentially reducing the problem to center - of - mass variables .
in the past few decades , the failures of the macro / micro distinction have also been highlighted by new experimental results . |
5,417 | Suppose that you have an abstract for a scientific paper: using the theory of elasticity of polymer gels we show that large - scale _ cross - link _ density patterns written into the structure of the network in the melt state , can be revealed upon swelling by monitoring the _ monomer _ density patterns .
we find that while isotropic deformations in good solvent yield magnified images of the original pattern , anisotropic deformations distort the image ( both types of deformation yield affinely stretched images in @xmath0 solvents ) . we show that in ordinary solids with spatially inhomogeneous profile of the shear modulus , isotropic stretching leads to distorted density image of this profile under isotropic deformation .
using simple physical arguments we demonstrate that the different response to isotropic stretching stems from fundamental differences between the theory of elasticity of solids and that of gels .
possible tests of our predictions and some potential applications are discussed . .
And you have already written the first three sentences of the full article: polymer networks are unique soft solids which can be significantly deformed without irreversible damage to their structure . a network is formed by cross - linking a melt or a semidilute solution of polymer chains .
once a homogeneous ( on length scales large compared to its `` mesh '' size ) network is formed , one can generate large - scale patterns in it by further cross - linking , followed by swelling ( and possibly stretching ) of the network , resulting in a gel inhomogeously swollen by solvent .
this can be done , for example , by adding light - sensitive cross - links to a transparent network . focusing a laser beam in regions inside the gel one can write information into gel structure in the form of @xmath1 or @xmath2 patterns of cross - linking density . in this paper.
Please generate the next two sentences of the article | we show that although such information is hidden at preparation conditions , it can be recovered by swelling the gel since unobservable variations of cross - link density in the melt are transformed into observable variations of monomer density in the swollen gel .
regions of a gel with increased cross - link concentration can be considered as inclusions with enhanced elastic modulus . |
5,418 | Suppose that you have an abstract for a scientific paper: quantization of constraint systems within the weyl - wigner - groenewold - moyal framework is discussed .
constraint dynamics of classical and quantum systems is reformulated using the skew - gradient projection formalism .
the quantum deformation of the dirac bracket is generalized to match smoothly the classical dirac bracket in and outside of the constraint submanifold in the limit @xmath0 . .
And you have already written the first three sentences of the full article: gauge symmetries provide mathematical basis for known fundamental interactions . within the generalized hamiltonian framework @xcite
, gauge theories correspond to first - class constraints systems . upon gauge fixing , these systems convert to second - class constraint systems .
the operator quantization schemes for constraints systems have been developed by dirac @xcite . the path integral quantization has also been developed and found to be especially effective for gauge theories ( for reviews see @xcite ) ..
Please generate the next two sentences of the article | besides conventional operator formulation of quantum mechanics and the path integral method , the popular approach to quantization of classical systems is based on the groenewold star - product formalism @xcite .
it takes the origin from the weyl s association rule @xcite between operators in the hilbert space and functions in phase space and the wigner function @xcite . |
5,419 | Suppose that you have an abstract for a scientific paper: within the framework of qcd light - cone sum rules ( lcsr ) , we calculate the form factor for @xmath0 transitions with chiral current correlator .
the resulting form factor depends on the distribution amplitude ( da ) of the @xmath1-meson .
we try to use three kinds of da models of the @xmath1-meson . in the velocity transfer region @xmath2 , which renders the operator product expansion ( ope ) near
light - cone @xmath3 go effectively , the yielding behavior of form factor is in agreement with that extracted from the data on @xmath4 , within the error . in the large recoil region @xmath5 ,
the results are observed consistent with those of perturbative qcd ( pqcd ) .
the presented calculation can play a bridge role connecting those from the lattice qcd , heavy quark symmetry and pqcd to have an all - around understanding of @xmath0 transitions .
* form factor for @xmath0 in the light - cone sum rules with chiral current correlator * * .3 cm fen zuo,@xmath6 zuo - hong li @xmath7 and tao huang @xmath8 * .
And you have already written the first three sentences of the full article: calculation of the form factors for semileptonic transitions of @xmath9 mesons has been being a subject discussed intensely .
recently , it has been shown that the @xmath10 transition form factor can be consistently analyzed by using the different approaches in the different @xmath11 regions @xcite . the perturbative qcd ( pqcd )
can be applied to the @xmath10 form factor in the large recoil ( small @xmath11 ) region and it is reliable when the involved energy scale is large enough @xcite ..
Please generate the next two sentences of the article | the qcd light - cone sum rules ( lcsr ) can involve both the hard and soft contributions to the @xmath10 form factor below @xmath12 @xcite .
the lattice qcd simulations of the @xmath10 transition form factor @xcite are available only for the soft region @xmath13 , because of the restriction to the @xmath14 energy smaller than the inverse lattice spacing . |
5,420 | Suppose that you have an abstract for a scientific paper: for systems in an externally controllable time - dependent potential , the optimal protocol minimizes the mean work spent in a finite - time transition between given initial and final values of a control parameter . for an initially thermalized ensemble ,
we consider both hamiltonian evolution for classical systems and schrdinger evolution for quantum systems . in both cases
, we show that for harmonic potentials , the optimal work is given by the adiabatic work even in the limit of short transition times .
this result is counter - intuitive because the adiabatic work is substantially smaller than the work for an instantaneous jump .
we also perform numerical calculations of the optimal protocol for hamiltonian dynamics in an anharmonic quartic potential . for a two - level spin system ,
we give examples where the adiabatic work can be reached in either a finite or an arbitrarily short transition time depending on the allowed parameter space . .
And you have already written the first three sentences of the full article: recently , there has been considerable progress in the thermodynamic description of small ( bio- ) systems @xcite which are prone to thermal fluctuations and typically driven far out of equilibrium . it has been shown that thermodynamic quantities obey various exact work and fluctuation theorems @xcite . the jarzynski relation connects the equilibrium free energy difference with an average of work values obtained from a series of nonequilibrium transitions @xcite .
while biomolecules are typically described by a langevin equation where effects of the thermal bath are included in friction and fluctuation terms , the jarzynski relation has originally been derived in the framework of purely hamiltonian dynamics with initial canonical equilibrium distribution @xcite .
this situation corresponds to an experiment where the heat bath of temperature @xmath0 is decoupled from a small hamiltonian system at time @xmath1 . during a time intevall.
Please generate the next two sentences of the article | @xmath2 $ ] a control parameter @xmath3 is varied time - dependently .
such dynamics has been used in various generalizations of the jarzynski relation @xcite and for the optimization of the free energy reconstruction from nonequilibrium work data @xcite . while this approach is elegant from a theoretical point of view , it is important to note that such a dynamics has quite different properties than a system subject to a permanent heat bath modelled _ |
5,421 | Suppose that you have an abstract for a scientific paper: the decay @xmath0 is discussed in the minimal supersymmetric standard model with general flavor mixing for squarks , at large @xmath1 . in this case , in addition to the chargino loop contributions which were analyzed in previous studies , @xmath1-enhanced contributions from the gluino and charged higgs boson loops might become sizable compared with the standard model contribution , at least in principle .
however , it is demonstrated that the experimental bounds on the new physics contributions to the radiative decay @xmath2 should strongly constrain these contributions to @xmath0 , especially on the gluino contribution .
we also briefly comment on a possible constraint from the @xmath3 decay .
tu-796 + youichi
yamada [ cols= " < " , ] pacs : 13.20.he , 12.60.jv .
And you have already written the first three sentences of the full article: recently , there has been significant experimental improvements in the measurements of flavor - changing neutral current ( fcnc ) processes of @xmath4 mesons at b factories and tevatron . for the @xmath5 transition , experimental data for @xmath2 and @xmath6 ( @xmath7 ) decays , @xmath8 oscillation , and @xmath3 decay have already started to constrain possible contributions from new physics beyond the standard model . here
we focus our attention to one of the @xmath5 processes , the decay into neutrino pairs @xcite , bs| .
[ eq - bsnunu ] it is known that the decays of the b mesons induced by the partonic process ( [ eq - bsnunu ] ) , especially the inclusive branching ratio @xmath9 , have small theoretical uncertainty due to the absence of photonic penguin and strong suppression of light quark contributions . on the other hand , experimental search of the decay ( [ eq - bsnunu ] ) is a hard task . at present , only the upper bounds are known for both inclusive @xcite and exclusive @xcite branching ratios , at 90% c.l . , & & _.
Please generate the next two sentences of the article | br(|bx_s|)<6.410 ^ -4 , + & & _
br(b^+k^+ |)<1.410 ^ -5 , + & & _ |
5,422 | Suppose that you have an abstract for a scientific paper: we present results from a short _ chandra_/acis - s observation of ngc 7618 , the dominant central galaxy of a nearby ( @xmath0=0.017309 , d=74.1 mpc ) group .
we detect a sharp surface brightness discontinuity 14.4 kpc n of the nucleus subtending an angle of 130@xmath1 with an x - ray tail extending @xmath2 70 kpc in the opposite direction . the temperature of the gas inside and outside the discontinuity is [email protected] and [email protected] kev , respectively .
there is marginal evidence for a discontinuous change in the elemental abundance ( @[email protected],@[email protected] at 90% confidence ) , suggesting that this may be an ` abundance ' front .
fitting a two - temperature model to the asca / gis spectrum of the ngc 7618/ugc 12491 pair shows the presence of a second , much hotter ( @[email protected] kev ) component .
we consider several scenarios for the origin of the edge and the tail including a radio lobe / igm interaction , non - hydrostatic ` sloshing ' , equal - mass merger and collision , and ram - pressure stripping . in the last case
, we consider the possibility that ngc 7618 is falling into ugc 12491 , or that both groups are falling into a gas poor cluster potential .
there are significant problems with the first two models , however , and we conclude that the discontinuity and tail are most likely the result of ram pressure stripping of the ngc 7618 group as it falls into a larger dark matter potential . .
And you have already written the first three sentences of the full article: the complex cluster morphology seen in x - ray images and in galaxy distributions gave support to the hypothesis that large structures form hierarchically ; that is , that small groups of galaxies merge to form low - mass subclusters , which then merge to form a massive rich cluster with the infalling groups aligned along large filaments .
galaxies and groups are the building blocks of the observable universe and contain the bulk of the observable baryons .
groups are estimated to contain a significant fraction , 20 - 30% , of the total matter in the universe ..
Please generate the next two sentences of the article | thus groups are important cosmological indicators of the distribution and properties of the dark matter . however , because they are not as luminous as clusters , they have received less study than their more massive cousins .
observations of rich clusters show many examples of pending or ongoing mergers of subclusters . |
5,423 | Suppose that you have an abstract for a scientific paper: we analyze the outcome of a mott insulator to superfluid transition for a two - component bose gas with two atoms per site in an optical lattice in the limit of slow ramping down the lattice potential .
this manipulation of the initial mott insulating state transforms local correlations between hyperfine states of atom pairs into multiparticle correlations extending over the whole system .
we show how to create macroscopic twin fock states in this way an that , in general , the obtained superfluid states are highly depleted even for initial ground mott insulator states . .
And you have already written the first three sentences of the full article: the experimental realization of degenerate atomic gases @xcite have opened up the possibility of engineering strongly correlated many - body quantum states .
such states are fundamental for the development of quantum technologies such as those implementing quantum information protocols and quantum computation .
a paramount example is the realization of a mott insulator ( mi ) @xcite in the lowest bloch band of an optical lattice which can serve as a quantum register @xcite ..
Please generate the next two sentences of the article | bose - einstein condensates of alkali atoms have also been proposed as systems to realize macroscopic superposition states @xcite or number correlated states ( also called twin fock states ) which are useful for quantum metrology @xcite .
in @xcite we proposed a method for engineering twin fock states via a two - component mi to superfluid ( sf ) transition . |
5,424 | Suppose that you have an abstract for a scientific paper: we describe a practical method for constructing axisymmetric two - integral galaxy models ( with distribution functions of the form @xmath0 , in which @xmath1 is the orbital energy , and @xmath2 is the vertical component of the angular momentum ) , based on schwarzschild s orbit superposition method .
other @xmath0-methods are mostly based on solving the jeans equations or on finding the distribution function directly from the density , which often places restrictions on the shape of the galaxy . here , no assumptions are made and any axisymmetric density distribution is possible .
the observables are calculated ( semi-)analytically , so that our method is faster than most previous , fully numerical implementations .
various aspects are tested extensively , the results of which apply directly to three - integral schwarzschild methods .
we show that a given distribution function can be reproduced with high accuracy and investigate the behaviour of the parameter that is used to measure the goodness - of - fit .
furthermore , we show that the method correctly identifies the range of cusp clopes for which axisymmetric two - integral models with a central black hole do not exist .
[ firstpage ] galaxies : elliptical and lenticular , cd - galaxies : kinematics and dynamics - galaxies : structure .
And you have already written the first three sentences of the full article: the fundamental quantity in galaxy dynamics is the distribution function ( df ) , which specifies the distribution of the stars in a galaxy over position and velocity . by jeans theorem ,
the df is a function of the isolating integrals that are conserved by the corresponding potential ( e.g. , lynden - bell 1962 ; binney 1982 ) .
axisymmetric galaxies , which we will study here , conserve at least the two classical integrals of motion , the energy @xmath1 and the vertical component of the angular momentum @xmath2 ..
Please generate the next two sentences of the article | the df can generally not be measured directly , but since observationally accessible quantities , such as the projected density and the line - of - sight velocity , are simple moments of the df , photometric and kinematic observations can provide information on its properties . in some cases , the part of a two - integral distribution function that is even in the velocities , @xmath3 , can be obtained analytically by using integral transforms to solve the relation between the df and the intrinsic density @xmath4 , where @xmath5 are the usual cylindrical coordinates . the odd part can be found similarly from @xmath6 , where @xmath7 is the mean streaming velocity .
these laplace ( lynden - bell 1962 ; lake 1981 ) , stieltjes ( hunter 1975b ) and laplace - mellin ( dejonghe 1986 ) transforms have the drawback that numerical implementation is difficult and that they require @xmath8 and @xmath9 to be explicit functions of the potential @xmath10 and the cylindrical radius @xmath11 . a more general formalism ( hunter & qian 1993 ; qian et al . 1995 , hereafter q95 ) , |
5,425 | Suppose that you have an abstract for a scientific paper: based on the analogue spacetime programme , and many other ideas currently mooted in `` quantum gravity '' , there is considerable ongoing speculation that the usual pseudo - riemannian ( lorentzian ) manifolds of general relativity might eventually be modified at short distances .
two specific modifications that are often advocated are the adoption of finsler geometries ( or more specifically , pseudo - finsler spacetimes ) and the possibility of birefringence ( or more generally , multi - refringence ) .
we have investigated the possibility of whether it is possible to usefully and cleanly deal with these two possibilities _ simultaneously_. that is , given two ( or more ) `` signal cones '' : is it possible to naturally and intuitively construct a `` unified '' pseudo - finsler spacetime such that the pseudo - finsler metric is null on these `` signal cones '' , _ but has no other zeros or singularities _ ?
our results are much less encouraging than we had originally hoped , and suggest that while pseudo - finsler spacetimes are certainly useful constructs , it is physically more appropriate to think of physics as taking place in a single topological manifold that carries several distinct pseudo - finsler metrics , one for each polarization mode
. [ section ] [ thm]corollary [ thm]lemma [ thm]proposition [ section ] [ section ] .
And you have already written the first three sentences of the full article: motivation for our work @xcite comes from various speculations that came up mainly from : * the analogue spacetime programme @xcite ; * various different approaches to `` quantum gravity '' , + ( loop quantum gravity @xcite , string models @xcite , causal dynamical triangulations @xcite ) ; * various different approaches to `` quantum gravity phenomenology '' , + ( dsr @xcite , vsr @xcite , noncommutative geometry @xcite ) ; * various different approaches to `` exotic '' cosmologies @xcite .
many of these approaches strongly suggest the possibility of high energy lorentz symmetry breaking @xcite and/or birefringence ( or multi - refringence ) @xcite .
if we wish to create a geometric theory encoding causal relations more complicated than those of special relativity , then we must unfortunately depart from the standard concept of pseudo - riemannian geometry , and adopt something more general ..
Please generate the next two sentences of the article | this more general geometry is almost inevitably a non - positive definite analogue of finsler geometry @xcite , that is , a geometry which can most descriptively be called a pseudo - finsler geometry @xcite .
( one might also try to generalize the spacetime in a slightly different direction by adopting the notion of an `` area metric '' @xcite , but we shall not take that particular route for now . ) |
5,426 | Suppose that you have an abstract for a scientific paper: the totally asymmetric simple exclusion process ( tasep ) on @xmath0 with the bernoulli-@xmath1 measure as initial conditions , @xmath2 , is stationary .
it is known that along the characteristic line , the current fluctuates as of order @xmath3 .
the limiting distribution has also been obtained explicitly . in this paper
we determine the limiting multi - point distribution of the current fluctuations moving away from the characteristics by the order @xmath4 .
the main tool is the analysis of a related directed last percolation model .
we also discuss the process limit in tandem queues in equilibrium . .
And you have already written the first three sentences of the full article: _ continuous time tasep . _
the totally asymmetric simple exclusion process ( tasep ) is the simplest non - reversible interacting stochastic particle system . in tasep , particles are on the lattice of integers , @xmath0 , with at most one particle at each site ( exclusion principle ) .
the dynamics is defined as follows ..
Please generate the next two sentences of the article | particles jump to the neighboring right site with rate @xmath5 provided that the site is empty .
jumps are independent of each other and take place after an exponential waiting time with mean @xmath5 , which is counted from the time instant when the right neighbor site is empty . |
5,427 | Suppose that you have an abstract for a scientific paper: we study the growth of hyperbolic type distances in starlike domains .
we derive estimates for various hyperbolic type distances and consider the asymptotic sharpness of the estimates .
@equation=@theorem keywords : hyperbolic type distance , starlike domain msc2010 : 30f45 , 51m10 , 30c65 .
And you have already written the first three sentences of the full article: the hyperbolic distance has turned out to be a useful tool in geometric function theory .
the basic models for the hyperbolic distance are the unit ball model and the upper half space model . using these models in the plane case @xmath0
, we can find the hyperbolic distance in any domain with at least 2 boundary points via the riemann mapping theorem . in higher dimensions @xmath1 , there are no such results we could use to consider the hyperbolic distance in general domains ..
Please generate the next two sentences of the article | a solution to this is to use other distance functions , which approximate the hyperbolic distance and are easier to evaluate .
we call this kind of distance functions hyperbolic type distances . |
5,428 | Suppose that you have an abstract for a scientific paper: the inclusive jet , dijet and trijet production cross - sections in deep - inelastic scattering ( dis ) at @xmath0 @xmath1 have been measured at the electron - proton collider hera by the h1 and zeus collaborations using data taken in 19982000 .
the jet cross - sections have been measured differentially in four - momentum transfer squared @xmath2 and jet transverse energy in the breit - frame @xmath3 with a typical precision of 510% limited by systematic uncertainties such as hadronization corrections and hadronic energy scale .
all jet observables are well described by perturbative qcd ( pqcd ) predictions at next - to - leading order ( nlo ) within the estimated accuracy of these calculations which is limited by the absence higher orders , and which is in general inferior to the experimental precision .
the values for the coupling constant @xmath4 of the strong interaction as determined by fits of pqcd predictions to the inclusive jet cross - section and the trijet - to - dijet production ratio @xmath5 are consistent for both experiments and both observables , and also are in excellent agreement with the world average . combining the individual measurements , a common value of @xmath6 is obtained . .
And you have already written the first three sentences of the full article: one of the many ways to determine @xmath4 is through the measurement of jet production in dis since the production cross section in leading order of @xmath7 jets ( not counting the proton remnant ) is proportional to @xmath8 . at hera
this measurement is particularly interesting since the hadronic final state is opened up in pseudo - rapidity .
the measurements of jet production cross - section presented here have many points in common which facilitates comparison of the extracted values of @xmath4 ..
Please generate the next two sentences of the article | in particular , jets are measured throughout using the longitudinally invariant @xmath9 algorithm in the breit - frame of reference , where in the naive quark parton model the struck quark and the virtual boson collide head - on .
hence , substantial transverse energy @xmath3 in the breit frame stems necessarily from qcd radiation and provides a natural energy scale for the determination of @xmath4 . |
5,429 | Suppose that you have an abstract for a scientific paper: the one - dimensional ( 1d ) tight binding model with random nearest neighbor hopping is known to have a singularity of the density of states and of the localization length at the band center .
we study numerically the effects of random long range ( power - law ) hopping with an ensemble averaged magnitude @xmath0 becomes smaller than 2 . .
And you have already written the first three sentences of the full article: the one - dimensional ( 1d ) tight - binding model of non - interacting electrons with random nearest neighbor hopping has been extensively studied since dyson s exact solution to density of states of one - dimensional random harmonic oscillators @xcite , which can be mapped to the random nearest neighbor hopping model .
mertsching gave a node counting scheme to study the density of states in a similar model@xcite .
since the early 80s , supersymmetry methods have been used to study such problems with randomness@xcite ..
Please generate the next two sentences of the article | all these studies show that there is a singularity in the one - electron density of states @xmath1 at the band center of the form @xmath2 .
concurrently , as a consequence of the thouless theorem @xcite , there is a logarithmic divergence of the localization length @xmath3 @xcite . |
5,430 | Suppose that you have an abstract for a scientific paper: the hypothesis about the relation between the observed alignment of spots in the x - ray film in cosmic ray emulsion experiments and the features of events in which jets prevail at super high energies is tested .
due to strong dynamical correlation between jet axis directions and that between momenta of jet particles ( almost collinearity ) , the evaluated degree of alignment is considerably larger than that for randomly selected chaoticly located spots in the x - ray film .
it appears comparable with experimental data provided that the height of primary interaction , the collision energy and the total energy of selected clusters meet certain conditions .
the monte carlo generator pythia , which basically well describes jet events in hadron - hadron interactions , was used for the analysis .
= -15 mm # 1#23.6pt * jet activity versus alignment * i.p .
lokhtin@xmath0 , a.k .
managadze@xmath1 , l.i .
sarycheva@xmath2 , a.m. snigirev@xmath3 + m.v.lomonosov moscow state university , d.v.skobeltsyn institute of nuclear physics , + 119992 , vorobievy gory , moscow , russia + + @xmath0e - mail : [email protected] + @xmath1e - mail : [email protected] + @xmath2e - mail : [email protected] + @xmath3e - mail : [email protected] + .
And you have already written the first three sentences of the full article: the intriguing phenomenon , the strong collinearity of cores in emulsion experiments @xcite , closely related to coplanar scattering of secondary particles in the interaction , has been observed long time ago .
so far there is no simple satisfactory explanation of these cosmic ray observations in spite of numerous attempts to find it ( see , for instance , @xcite and references therein ) . among them ,
the jet - like mechanism @xcite looks very attractive and gives the natural explanation of alignment of three spots along the straight line which results from momentum conservation in a simple parton picture of scattering ..
Please generate the next two sentences of the article | besides , the strong momentum correlation of particles inside a jet and correlation between jet axes due to singularity of qcd matrix elements allow us to suggest the high degree of alignment for more than 3 spots .
this has been already demonstrated for the four cores in @xcite but using a simplified picture of hadronization . |
5,431 | Suppose that you have an abstract for a scientific paper: we investigate @xmath0 partition function of @xmath1 supersymmetric gauge theories . a gauge theory on the orbifold
has degenerate vacua specified by the holonomy .
the partition function is obtained by summing up the contributions of saddle points with different holonomies .
an appropriate choice of the phase of each contribution is essential to obtain the partition function .
we determine the relative phases in the holonomy sum in a few examples by using duality to non - gauge theories . in the case of odd @xmath2
the phase factors can be absorbed by modifying a single function appearing in the partition function . .
And you have already written the first three sentences of the full article: for last few years , there was large progress in supersymmetric field theories in three - dimension .
many physical quantities in strongly coupled field theories have been computed by using localization method .
for example , partition functions of @xmath3 supersymmetric field theories in @xmath4 @xcite and @xmath5 @xcite are computed exactly , and they have been used to study non - perturbative aspects of three - dimensional field theories , such as dualities among three - dimensional field theories @xcite and relation to m - theory via ads / cft correspondence @xcite in this paper , we investigate the partition function of three - dimensional @xmath3 supersymmetric field theories in the orbifold @xmath6 @xcite . due to the non - trivial homotopy of the orbifold , @xmath7 , a gauge theory defined in it has degenerate vacua specified by the holonomy associated with the gauge symmetry ..
Please generate the next two sentences of the article | their contributions are summed up to obtain the total partition function . in general , the partition function of a euclidean theory is complex .
we usually focus only on its absolute value and the phase is disregarded . |
5,432 | Suppose that you have an abstract for a scientific paper: the full dynamics of a synchronous recurrent neural network model with ising binary units and a hebbian learning rule with a finite self - interaction is studied in order to determine the stability to synaptic and stochastic noise of frozen - in states that appear in the absence of both kinds of noise .
both , the numerical simulation procedure of eissfeller and opper and a new alternative procedure that allows to follow the dynamics over larger time scales have been used in this work .
it is shown that synaptic noise destabilizes the frozen - in states and yields either retrieval or paramagnetic states for not too large stochastic noise .
the indications are that the same results may follow in the absence of synaptic noise , for low stochastic noise . .
And you have already written the first three sentences of the full article: the dynamics of recurrent neural network models with synchronous updating has been of interest ever since the work of little @xcite .
it is expected that little s model with binary units and symmetric hebbian couplings should exhibit either cycles of period two or fixed - point attractors and it has been suggested that the cycles could arise in statistical mechanics from a duplication of phase space by means of two state variables for every unit .
an equilibrium analysis , based on replica symmetry , predicted that period - two cycles associated with a full spin flip ( all units changing sign at each time step ) should occur in a zero temperature paramagnetic phase ..
Please generate the next two sentences of the article | this was recognized as an unphysical phase apparently disconnected from the ordinary high temperature paramagnetic phase . a somewhat large negative self - interaction @xmath0 ( the diagonal elements of the synaptic matrix ) between units turned out to be necessary for this cyclic solution with full spin flip to appear @xcite .
early numerical simulations failed to show the presence of those cycles and lead to the conjecture that the problem with the statistical mechanics approach could be due to the assumption of replica symmetry . |
5,433 | Suppose that you have an abstract for a scientific paper: we study distributions of persistent homology barcodes associated to taking subsamples of a fixed size from metric measure spaces .
we show that such distributions provide robust invariants of metric measure spaces , and illustrate their use in hypothesis testing and providing confidence intervals for topological data analysis . .
And you have already written the first three sentences of the full article: topological data analysis assigns homological invariants to data presented as a finite metric space ( a `` point cloud '' ) .
if we imagine this data as measurements sampled from some abstract universal space @xmath0 , the structure of that space is a metric measure space , having a notion both of distance between points and a notion of probability for the sampling . a standard homological approach to studying the samples is to assign a simplicial complex and compute its homology .
the construction of the associated simplicial complex for a point cloud depends on a choice of scale parameter ..
Please generate the next two sentences of the article | the insight of `` persistence '' is that one should study homological invariants that encode change across scales ; the correct scale parameter is a priori unknown . as such , a first approach to studying the homology of @xmath0 from the samples is to simply compute the persistent homology @xmath1 of simplicial complexes associated to the sampled point cloud @xmath2 .
we can gain some perspective from imagining that we could make measurements on @xmath0 directly and interpret these measurements in terms of random sample points . with this in mind |
5,434 | Suppose that you have an abstract for a scientific paper: neutron rich matter is at the heart of many fundamental questions in nuclear physics and astrophysics .
what are the high density phases of qcd ? where did the chemical elements come from ?
what is the structure of many compact and energetic objects in the heavens , and what determines their electromagnetic , neutrino , and gravitational - wave radiations ?
moreover , neutron rich matter is being studied with an extraordinary variety of new tools such as facility for rare isotope beams ( frib ) and the laser interferometer gravitational wave observatory ( ligo ) .
we describe the lead radius experiment ( prex ) that is using parity violation to measure the neutron radius in 208pb .
this has important implications for neutron stars and their crusts . using large scale molecular dynamics
, we model the formation of solids in both white dwarfs and neutron stars .
we find neutron star crust to be the strongest material known , some 10 billion times stronger than steel .
it can support mountains on rotating neutron stars large enough to generate detectable gravitational waves .
finally , we describe a new equation of state for supernova and neutron star merger simulations based on the virial expansion at low densities , and large scale relativistic mean field calculations . .
And you have already written the first three sentences of the full article: neutron rich matter is at the heart of many fundamental questions in nuclear physics and astrophysics .
* what are the high density phases of qcd ? * where did the chemical elements come from ?
* what is the structure of many compact and energetic objects in the heavens , and what determines their electromagnetic , neutrino , and gravitational - wave radiations ?.
Please generate the next two sentences of the article | furthermore , neutron rich matter is being studied with an extraordinary variety of new tools such as the facility for rare isotope beams ( frib ) , a heavy ion accelerator to be built at michigan state university , and the laser interferometer gravitational wave observatory ( ligo ) .
indeed there are many , qualitatively different , probes of neutron rich matter including precision laboratory experiments on stable nuclei and experiments with neutron rich radioactive beams . while astrophysical observations probe neutron rich matter with electromagnetic radiation , neutrinos , and gravitational waves . finally , there are new theoretical probes of neutron rich matter that have been enabled by tremendous advances in computational science . in this paper |
5,435 | Suppose that you have an abstract for a scientific paper: using the theory of plugs and the self - insertion construction due to the second author , we prove that a foliation of any codimension of any manifold can be modified in a real analytic or piecewise - linear fashion so that all minimal sets have codimension 1 . in particular , the 3-sphere @xmath0 has a real analytic dynamical system such that all limit sets are 2-dimensional .
we also prove that a 1-dimensional foliation of a manifold of dimension at least 3 can be modified in a piecewise - linear fashion so that so that there are no closed leaves but all minimal sets are 1-dimensional .
these theorems provide new counterexamples to the seifert conjecture , which asserts that every dynamical system on @xmath0 with no singular points has a periodic trajectory .
[ theorem]proposition [ theorem]lemma [ theorem]definition [ theorem]corollary 1dim # 1 by # 2 ( # 3 ) to # 2 ' '' '' width # 1 height 0pt depth 0pt .
And you have already written the first three sentences of the full article: in 1950 , h. seifert @xcite asked whether every dynamical system on the 3-sphere with no singular points has a periodic trajectory .
the conjecture that the answer is yes became known as the seifert conjecture .
seifert proved the conjecture for perturbations of the flow parallel to the hopf fibration . in 1974 , p. a. schweitzer @xcite found a @xmath1 counterexample to the seifert conjecture , which was modified to a @xmath2 counterexample by j. harrison @xcite . in 1993 , h. hofer @xcite proved the conjecture for contact flows ..
Please generate the next two sentences of the article | the main idea of this paper comes from the construction of a smooth counterexample to the seifert conjecture due to the second author @xcite . here
, we outline more general consequences of that idea . |
5,436 | Suppose that you have an abstract for a scientific paper: we consider a class of homogeneous partial differential operators on a finite - dimensional vector space and study their associated heat kernels .
the heat kernels for this general class of operators are seen to arise naturally as the limiting objects of the convolution powers of complex - valued functions on the square lattice in the way that the classical heat kernel arises in the ( local ) central limit theorem .
these so - called positive - homogeneous operators generalize the class of semi - elliptic operators in the sense that the definition is coordinate - free .
more generally , we introduce a class of variable - coefficient operators , each of which is uniformly comparable to a positive - homogeneous operator , and we study the corresponding cauchy problem for the heat equation . under the assumption that such an operator has hlder continuous coefficients , we construct a fundamental solution to its heat equation by the method of e. e. levi , adapted to parabolic systems by a. friedman and s. d. eidelman . though our results in this direction are implied by the long - known results of s. d. eidelman for @xmath0-parabolic systems ,
our focus is to highlight the role played by the legendre - fenchel transform in heat kernel estimates .
specifically , we show that the fundamental solution satisfies an off - diagonal estimate , i.e. , a heat kernel estimate , written in terms of the legendre - fenchel transform of the operator s principal symbol
an estimate which is seen to be sharp in many cases . _ dedicated to professor rodrigo bauelos on the occasion of his 60th birthday . _
* keywords : * semi - elliptic operators , quasi - elliptic operators , @xmath0-parabolic operators , heat kernel estimates , legendre - fenchel transform . + * mathematics subject classification : * primary 35h30 ; secondary 35k25 . .
And you have already written the first three sentences of the full article: in this article , we consider a class of homogeneous partial differential operators on a finite dimensional vector space and study their associated heat kernels .
these operators , which we call nondegenerate - homogeneous operators , are seen to generalize the well - studied classes of semi - elliptic operators introduced by f. browder @xcite , also known as quasi - elliptic operators @xcite , and a special positive " subclass of semi - elliptic operators which appear as the spatial part of s. d. eidelman s @xmath0-parabolic operators @xcite . in particular , this class of operators contains all integer powers of the laplacian . to motivate the definition of nondegenerate - homogeneous operators , given in the next section
, we first introduce the class of semi - elliptic operators ..
Please generate the next two sentences of the article | semi - elliptic operators are seen to be prototypical examples of nondegenerate - homogeneous operators ; in fact , the definition of nondegenerate - homogeneous operators is given to formulate the following construction in a basis - independent way .
given @xmath1-tuple of positive integers @xmath2 and a multi - index @xmath3 , set @xmath4 . |
5,437 | Suppose that you have an abstract for a scientific paper: in this paper we show that electron - positron pairs can be pumped inexhaustibly with a constant production rate from the one - dimensional well potential with oscillating depth or width .
bound states embedded in the the dirac sea can be pulled out and pushed to the positive continuum , become scattering states .
pauli block , which dominant the saturation of pair creation in the static super - critical well potential , can be broken by the ejection of electrons .
we find that the width oscillating mode is more efficient that the depth oscillating mode . in the adiabatic limit , pair number as a function of upper boundary of the oscillating , will reveal the diving of the bound states . .
And you have already written the first three sentences of the full article: since einstein s relativistic theory tell that the matter can convert into energy , the possibility of converting energy into matter , i.e. , the electron - positron pair , as predicted by dirac in quantum electrodynamics @xcite , has attracted a great deal of interest@xcite . in presence of a static and uniform electric field , the quantum electrodynamic ( qed ) vacuum may break down and decay into electron - positron pairs due to a quantum tunneling effect @xcite .
the critical schwinger field is @xmath0 , which can accelerate the electron to an energy of the order of its rest mass on its compton wavelength @xmath1 , where @xmath2 is the electron mass .
starting from the works of brezin and popov et.al @xcite , the schwinger mechanism was generalized to time dependent fields @xcite , where another mechanism may be responsible for the pair creation ..
Please generate the next two sentences of the article | if the frequency of the alternating field exceeds the gap @xmath3 , electrons in dirac sea can transit to positive states and pairs are triggered .
experimentally , pairs can be generated by the relativistic heavy - ion collisions@xcite or the collision of an intense laser pulse and a 46 gev electron beam@xcite , but pairs created from pure laser light has not been observed until now . |
5,438 | Suppose that you have an abstract for a scientific paper: the ruddlesden - popper ( rp ) homologous series sr@xmath0ti@xmath1o@xmath2 provides a useful template for the study and control of the effects of dimensionality and quantum confinement on the excited state properties of the complex oxide srtio@xmath3 .
we use _ ab initio _ many - body perturbation theory within the @xmath4 approximation and the bethe - salpeter equation approach to calculate quasiparticle energies and absorption spectrum of sr@xmath0ti@xmath1o@xmath2 for @xmath5 and @xmath6 .
our computed direct and indirect optical gaps are in excellent agreement with spectroscopic measurements .
the calculated optical spectra reproduce the main experimental features and reveal excitonic structure near the gap edge .
we find that electron - hole interactions are important across the series , leading to significant exciton binding energies that increase for small @xmath7 and reach a value of 330 mev for @xmath8 , a trend attributed to increased quantum confinement .
we find that the lowest - energy singlet exciton of sr@xmath9tio@xmath10 ( @xmath8 ) localizes in the 2d plane defined by the tio@xmath9 layer , and explain the origin of its localization .
2.5 in 0.5 in # 1 strontium titanite ( srtio@xmath3 ) is a prototypical abo@xmath3 perovskite that , in pure , doped or strained form , displays important dielectric , optoelectronic , and transport properties , such as ferroelectricity @xcite , robust photocatalysis @xcite , superconductivity @xcite and high electron mobility at low temperatures @xcite .
atomically thin two - dimensional layers in srtio@xmath3 heterostructures display exotic electronic effects , such as an emergent two - dimensional electron gas @xcite , magnetism @xcite , and metal - insulator transitions @xcite . recently , anomalous excitonic phenomena have been observed in the optical spectrum of cubic srtio@xmath3 @xcite .
these effects , previously overlooked , arise due to strong coulomb interactions between excited electrons and holes in the absence of....
And you have already written the first three sentences of the full article: s.e.r .- l . thanks r.f . berger and t. birol for valuable discussions .
work at the molecular foundry was supported by the office of science , office of basic energy sciences , of the u.s .
department of energy , and laboratory directed research and development program at the lawrence berkeley national laboratory under contract no ..
Please generate the next two sentences of the article | de - ac02 - 05ch11231 . t.r . acknowledges support from the scidac program on excited state phenomena in energy materials .
f.b . acknowledges the enhanced eurotalent program and the france berkeley fund for supporting his sabbatical leave in uc berkeley . |
5,439 | Suppose that you have an abstract for a scientific paper: galaxies with stellar bulges are generically observed to host supermassive black holes ( smbhs ) .
the hierarchical merging of galaxies should therefore lead to the formation of smbh binaries .
merging of old massive galaxies with little gas promotes the formation of low - density nuclei where smbh binaries are expected to survive over long times .
if the binary lifetime exceeds the typical time between mergers , then triple black hole ( bh ) systems may form .
we study the statistics of close triple - smbh encounters in galactic nuclei by computing a series of 3-body orbits with physically - motivated initial conditions appropriate for giant elliptical galaxies .
our simulations include a smooth background potential consisting of a stellar bulge plus a dark matter halo , drag forces due to gravitational radiation and dynamical friction on the stars and dark matter , and a simple model of the time evolution of the inner density profile under heating and mass ejection by the smbhs .
we find that the binary pair coalesces as a result of repeated close encounters in @xmath085% of our runs , and in @xmath015% of cases a new eccentric binary forms from the third smbh and binary remnant and coalesces during the run time . in about 40% of the runs the lightest bh
is left wandering through the galactic halo or escapes the galaxy altogether , but escape of all three smbhs is exceedingly rare .
the triple systems typically scour out cores with mass deficits @xmath01 - 2 @xmath1 their total mass , which can help to account for the large cores observed in some massive elliptical galaxies , such as m87 .
the high coalescence rate , prevalence of very high - eccentricity orbits , and gravitational radiation `` spikes '' during close encounters in our runs , may provide interesting signals for the future laser interferometer space antenna ( lisa ) .
[ firstpage ] black hole physics cosmology : theory galaxies : elliptical and lenticular , cd galaxies : interactions galaxies : nuclei methods : numerical .
And you have already written the first three sentences of the full article: in the favored cold dark matter cosmology , present - day galaxies were assembled hierarchically from smaller building blocks at earlier cosmic times . since all nearby galaxies with stellar spheroids are observed to host nuclear smbhs @xcite , hierarchical merging leads inevitably to the formation of smbh binaries @xcite .
if the binary lifetime exceeds the typical time between mergers , then some galactic nuclei should contain systems of three or more smbhs .
these systems are particularly interesting as they often lead to the ejection of one of the bhs at a speed comparable to the galactic escape velocity @xcite . in massive elliptical galaxies.
Please generate the next two sentences of the article | the typical speeds are @xmath2 , far greater than attainable through gravitational radiation recoil @xcite . spatially resolved pairs of nuclei have been observed in a few active galaxies .
the most famous example is ngc 6240 , an ultraluminous infrared galaxy ( ulirg ) in which two distinct active galactic nuclei ( agn ) are clearly seen in hard x - rays at a projected separation of @xmath01 kpc @xcite . |
5,440 | Suppose that you have an abstract for a scientific paper: the extrasolar planets ( eps ) so far detected are very different to the planets in our own solar system .
many of them have jupiter - like masses and close - in orbits ( the so - called hot planets , hps ) , with orbital periods of only a few days . in this paper
, we present a new statistical analysis of the observed eps , focusing on the origin of the hps . among the several hp formation mechanisms proposed so far , the two main formation mechanisms are type ii migration and scattering . in both cases , planets form beyond the so - called snow - line of the protoplanetary disk and then migrate inward due to angular momentum and energy exchange with either the protoplanetary disk or with companion planets .
although theoretical studies produce a range of observed features , no firm correspondence between the observed eps and models has yet been established . in our analysis , by means of principal component analysis and hierarchical cluster analysis , we find convincing indications for the existence of two types of hps , whose parameters reflect physical mechanisms of type ii migration and scattering .
[ firstpage ] planets and satellites : formation planetary systems : formation planetary systems : protoplanetary discs . .
And you have already written the first three sentences of the full article: the present eps database consists of a rather heterogeneous sample of planets , showing great variety in all the measured quantities .
statistical analysis provides a necessary means to find correlations among various physical parameters involved in planetary formation and evolution .
nevertheless , we caution that statistical analysis may not be able to disclose important relationships due to the complex and -mostly unknown- interplay of the involved parameters . in order to overcome such problems.
Please generate the next two sentences of the article | , we performed a global statistical analysis of the eps , using a novel approach .
the underlying idea is to find groups of _ similar _ eps and to distinguish different ep groups on the basis of their _ diversity_. in this work , the concept of similarity and diversity among eps is quantified by means of a distance measure in the multifold space of physical parameters . |
5,441 | Suppose that you have an abstract for a scientific paper: the thermodynamic properties of a classical @xmath0-dimensional spin-@xmath1 heisenberg ferromagnet , with long - range interactions decaying as @xmath2 and in the presence of an external magnetic field , is investigated by means of the spectral density method in the framework of classical statistical mechanics .
we find that long - range order exists at finite temperature for @xmath3 with @xmath4 and for @xmath5 with @xmath6 , consistently with known theorems .
besides , the related critical temperature is determined and a study of the critical properties is performed . , and classical heisenberg model , long - range interactions .
05.20.-y , 75.10.hk , 64.60.fr .
And you have already written the first three sentences of the full article: the quantum two - time green function technique has provided a very powerful tool in condensed matter physics for exploring the equilibrium and transport properties of a wide variety of many - body systems . within this framework ,
the equation of motion method ( emm ) and the spectral density method ( sdm ) allow to obtain reliable approximations to treat typically unperturbative problems @xcite . the pioneering introduction of the two - time green functions and the emm in classical statistical mechanics by bogoljubov and sadovnikov @xcite , has opened the concrete possibility to describe classical and quantum systems on the same footing .
nextly , a classical version of the sdm ( csdm ) has been also formulated in extensive @xcite and nonextensive @xcite classical statistical mechanics and applied to classical magnetic chains @xcite ..
Please generate the next two sentences of the article | the last method , which seems to present many advantages with respect to the most conventional emm @xcite , offers a robust instrument for systematic and well tested approximations @xcite to explore the macroscopic properties of classical many - body systems as well .
unfortunately , both the mentioned methods have not received the due consideration in the classical context and further developments and applications are desiderable . along this direction , in this paper we apply the csdm to investigate the thermodynamic properties of a highly nontrivial @xmath7-dimensional classical spin-@xmath1 heisenberg ferromagnet with long - range interactions decaying as @xmath2 ( @xmath5 ) with the distance @xmath8 between spins in the presence of an external magnetic field . |
5,442 | Suppose that you have an abstract for a scientific paper: a sample of 286 gamma - ray bursts , detected by swift satellite , is studied statistically by the @xmath0 test and the student t - test , respectively .
the short and long subgroups are well detected in the swift data .
but no intermediate subgroup is seen .
the non - detection of this subgroup in the swift database can be explained , once it is assumed that in the batse database the short and the intermediate subgroups form a common subclass .
address = astronomical institute of the charles university , v holeovikch 2 , prague , czech republic address = astronomical institute of the charles university , v holeovikch 2 , prague , czech republic .
And you have already written the first three sentences of the full article: according to our knowledge , gamma - ray bursts ( grbs ) are the most powerful mysterious explosions the universe has ever seen since the big bang . with swift satellite , since november 20 , 2004 , we have a tool , which can solve the gamma - ray burst mystery .
we define two samples from the swift dataset @xcite : the sample of grbs without measured redshift @xmath1 ( 189 grbs ) , and the sample with measured @xmath1 ( 97 grbs ) .
the swift catalogue consists of the name of grb , its bat duration @xmath2 , bat fluence at range 15 - 150 kev , bat peak flux at range 15 - 150 kev , and redshift ..
Please generate the next two sentences of the article | the sample covers the period november 2004 - december 2007 ; the first / last event is grb041227 / grb071227 .
we have studied both samples separately and also together as the whole sample ( 286 grbs ) . |
5,443 | Suppose that you have an abstract for a scientific paper: we present results from our quantitative study of statistical and network properties of literary and scientific texts written in two languages : english and polish .
we show that polish texts are described by the zipf law with the scaling exponent smaller than the one for the english language .
we also show that the scientific texts are typically characterized by the rank - frequency plots with relatively short range of power - law behavior as compared to the literary texts .
we then transform the texts into their word - adjacency network representations and find another difference between the languages . for the majority of the literary texts in both languages
, the corresponding networks revealed the scale - free structure , while this was not always the case for the scientific texts .
however , all the network representations of texts were hierarchical .
we do not observe any qualitative and quantitative difference between the languages .
however , if we look at other network statistics like the clustering coefficient and the average shortest path length , the english texts occur to possess more clustered structure than do the polish ones .
this result was attributed to differences in grammar of both languages , which was also indicated in the zipf plots .
all the texts , however , show network structure that differs from any of the watts - strogatz , the barbasi - albert , and the erds - rnyi architectures . .
And you have already written the first three sentences of the full article: natural language is an evolving system whose present structure can doubtlessly be considered a product of long history of self - organization @xcite . like for many other self - organized systems known in nature ,
the observables associated with language , being , for example , written texts or spoken messages , reveal quite sophisticated dynamics .
any language sample by no means is an amorphous mixture of symbols ( letters , phonemes , morphemes , words , etc . ) but rather a highly organized sequence in which particular symbols are ordered according to specific rules most of which are defined by the language grammar . since the existence of grammar is an emergent phenomenon @xcite , language can be counted among the complex systems @xcite ..
Please generate the next two sentences of the article | the grammatical rules together with the information content impose on the language elements relations which can be most easily expressed in a form of network where , for instance , words are expressed by nodes and their relations by edges .
some earlier attempts along this way were presented in refs . |
5,444 | Suppose that you have an abstract for a scientific paper: we revisit recent claims about the instability of non - rotating tunnel coupled annular bose - einstein condensates leading to the emergence of angular - momentum josephson oscillation [ phys .
rev .
lett . * 98 * , 050401 ( 2007 ) ] .
it was predicted that all stationary states with uniform density become unstable in certain parameter regimes . by careful analysis
, we arrive at a different conclusion .
we show that there is a stable non - rotating and uniform ground state for any value of the tunnel coupling and repulsive interactions .
the instability of an excited state with @xmath0 phase difference between the condensates can be interpreted in terms of the familiar snake instability .
we further discuss the sign of the tunnel coupling through a separating barrier , which carries significance for the nature of the stationary states .
it is found to always be negative for physical reasons . .
And you have already written the first three sentences of the full article: bose - einstein condensates ( becs ) located in different minima of an external potential created by magnetic or light forces and coupled by tunneling through a potential barrier have been the host to many exciting developments and discoveries in recent years @xcite .
phenomena explored include analogs of the josephson effect in double or multiple quantum - well structures @xcite , gap solitons of repulsive becs @xcite , and quantum phase transitions @xcite
. often these systems are modeled by considering just one mode per potential minimum and their linear coupling provided by tunnling through a separating barrier ..
Please generate the next two sentences of the article | these simplified models , which are usually labelled as two - mode or multiple - mode models , variants of the bose - hubbard model , or the discrete nonlinear schrdinger equation , are tailored to describe certain properties or aspects of the dynamics of the many - body system under investigation . although there is an abundance of literature on such models @xcite ,
there still appear to exist misconceptions about the nature of the effective model parameters , especially the sign of the tunnel coupling , as only few works attempt to calculate such parameters based on a more complete theoretical treatment @xcite . |
5,445 | Suppose that you have an abstract for a scientific paper: we present the results from two radio integrations at 8.4 ghz using the vla .
one of the fields , at 13@xmath0 + 43@xmath1 ( sa13 field ) , has an rms noise level of @xmath2jy and is the deepest radio image yet made .
thirty - four sources in a complete sample were detected above @xmath3jy and 25 are optically identified to a limit of i=25.8 , using our deep hst and ground - based images .
the radio sources are usually located within @xmath4 ( typically 5 kpc ) of a galaxy nucleus , and generally have a diameter less than @xmath5 .
the second field at 17@xmath0 + 50@xmath1 ( hercules field ) has an rms noise of @xmath6jy and contains 10 sources .
we have also analyzed a complete flux density - limited sample at 8.4 ghz of 89 sources from five deep radio surveys , including the hubble deep and flanking fields as well as the two new fields .
half of all the optical counterparts are with galaxies brighter than i=23 mag , but 20% are fainter than i=25.5 mag .
we confirm the tendency for the micro - jansky radio sources to prefer multi - galaxy systems .
the distribution of the radio spectral index between 1.4 and 8.4 ghz peaks at @xmath7 ) , with a median value of @xmath8 .
the average spectral index becomes steeper ( lower values ) for sources below @xmath6jy , and for sources identified with optical counterparts fainter than i=25.5 mag .
this correlation may suggest that there is an increasing contribution from star - burst galaxies compared to active galactic nuclei ( agns ) at lower radio flux densities and fainter optical counterparts .
the differential radio count between 7.5 and 1000 @xmath9jy has a slope of @xmath10 and a surface density of 0.64 sources ( arcmin)@xmath11 with flux density greater than @xmath3jy . .
And you have already written the first three sentences of the full article: deep surveys of the extragalactic sky have been made at x - ray ( hasinger et al .
1998 ; cowie et al . 2001 ) , optical ( lilly et al.1996 ; madau et al .
1996 ; steidel et al ..
Please generate the next two sentences of the article | 1999 ) , infra - red ( goldschmidt et al . 1997 ; rowan - robinson et al . 1997 ; elbaz et al .
1999 ) , sub - mm ( hughes et al . 1998 ; barger et al . 1999 ; blain et al . 1999 ; barger et al . 2000 ; scott et al . |
5,446 | Suppose that you have an abstract for a scientific paper: we study the @xmath0 production mechanism in @xmath1 annihilations in the framework of hadronic molecules and investigate the consequence of such a picture in different decay channels . in the hadronic molecule picture the @xmath0
is described as a mixture state composed of a long - ranged @xmath2 molecule state and a compact @xmath3 component .
we show that the compositeness relation can still provide a reasonable constraint on the wavefunction renormalization parameter due to the dominance of the molecular component .
such a mechanism can be regarded as a natural consequence of the heavy quark spin symmetry ( hqss ) breaking .
this study elaborates the molecular picture for the @xmath0 in the @xmath1 annihilations and affirms that the cross section lineshape of @xmath4 in the vicinity of the @xmath0 should have a nontrivial behavior .
in this framework we predict that the upper limit of the @xmath0 leptonic decay width is about 500 ev .
we also investigate the coupling for @xmath5 in the @xmath6 quark model and examine the possible hqss breaking effects due to the deviation from the @xmath7 and @xmath8 ideal mixing .
this will in turn provide a constraint on the hqss breaking coupling for the @xmath0 to @xmath2 via its @xmath3 component . .
And you have already written the first three sentences of the full article: the study of hadron spectroscopy has made significant progress during the past decade benefiting from the experimental observations of a lot of new states in various processes . in particular , in the heavy flavor sector , a large number of the so - called @xmath9 , @xmath10 , @xmath11 states have been candidates for exotic hadrons which may contain more complicated quark - gluon structures than the conventional quark model picture . among all those exotic candidates ,
the @xmath0 is undoubtedly one of the most mysterious states and has initiated a lot of experimental and theoretical studies since its observation by babar collaboration in the @xmath12 channel in 2005 @xcite .
it was later confirmed by belle @xcite and cleo - c collaboration @xcite in the same decay channel , but evaded " from observation in its decays into open charm channels @xcite which is unexpected for conventional charmonium states above the @xmath13 threshold ..
Please generate the next two sentences of the article | nevertheless , in the @xmath14 value measurement the inclusive cross sections for @xmath1 annihilations appear to have a dip instead of a peak in the vicinity of the @xmath0 mass region .
another important observation which makes @xmath0 peculiar is that the successful potential quark model calculations did not predict a vector state in such an energy region and the conventional @xmath3 states have been assigned to other structures @xcite . |
5,447 | Suppose that you have an abstract for a scientific paper: sergey pinchuk found a polynomial map from the real plane to itself which is a local diffeomorphism but is not one - to - one .
the aim of this paper is to give a geometric description of pinchuk s map . .
And you have already written the first three sentences of the full article: in the paper @xcite pinchuk gave an example of a polynomial map @xmath0 with a non - vanishing jacobian such that @xmath1 is not a global diffeomorphism .
let us recall his construction .
we define the following auxiliary polynomials in variables @xmath2 , @xmath3 : @xmath4 and a polynomial @xmath5 then @xmath6 where @xmath7 and @xmath8 are given by @xmath9 our aim is to give a geometric description of pinchuk s map . as in @xcite.
Please generate the next two sentences of the article | we find the set of points at which @xmath1 is not proper .
it allows us to divide the image of @xmath1 into sets with constant multiplicity of fibers . |
5,448 | Suppose that you have an abstract for a scientific paper: we study the competition between the exchange and the direct coulomb interaction near the edge of a two - dimensional electron gas in a strong magnetic field using density - functional theory in a local approximation for the exchange - energy functional .
exchange is shown to play a significant role in reducing the spatial extent of the compressible edge channel regions obtained from an electrostatic description .
the transition from the incompressible edge channels of the hartree - fock picture to the broad , compressible strips predicted by electrostatics occurs within a narrow and experimentally accessible range of confinement strengths .
+ + pacs numbers : 73.20.dx ; 71.10.+x , 71.45.gm + + submitted to phys .
rev . .
And you have already written the first three sentences of the full article: the concept of current - carrying edge channels accounts for the magnetotransport properties of a two - dimensional electron gas ( 2deg ) in a high magnetic field , both in the integer@xcite and fractional@xcite quantum hall regime .
although the initial theoretical studies have used a noninteracting picture of edge channels , a considerable effort has recently been devoted to understand the effects of electron - electron interactions in the _ integer _ quantum hall regime.@xcite at present there are two incompatible pictures for the electronic ground state of edge channels in the integer quantum hall regime . in the hartree - fock approximation
the ground state wave function is a single slater determinant , which corresponds to occupation numbers zero and one.@xcite in this description the edge state is incompressible and the electron density drops rapidly at the edges , on a length scale which is typically of the order of the magnetic length ..
Please generate the next two sentences of the article | although the hartree - fock approximation is widely used for the description of quantum dots and wires,@xcite it has been challenged on the grounds that is does not take the global electrostatics into account properly.@xcite in the electrostatic description given in ref .
a more gradual variation of the electron density at the edge is found energetically favorable . here |
5,449 | Suppose that you have an abstract for a scientific paper: on the way to solid - state quantum computing , overcoming decoherence is the central issue . in this contribution
, we discuss the modeling of decoherence of a superonducting flux qubit coupled to dissipative electronic circuitry .
we discuss its impact on single qubit decoherence rates and on the performance of two - qubit gates .
these results can be used for designing decoherence - optimal setups .
quantum computation is one of the central interdisciplinary research themes in present - day physics @xcite .
it promises a detailed understanding of the often counterintuitive predictions of basic quantum mechanics as well as a qualitative speedup of certain hard computational problems . a generic ,
although not necessarily exclusive , set of criteria for building quantum computers has been put forward by divincenzo @xcite .
the experimental realization of quantum bits has been pioneered in atomic physics , optics and nmr . there
, the approach is taken to use microscopic degrees of freedom which are well isolated and can be kept quantum coherent over long times .
efficient controls are attached to these degrees of freedom . even though these approaches are immensely succesful demonstrating elementary operations , it is not evident how they can be scaled up to macroscopic computers .
solid - state systems on the other hand have proven to be scalable in present - day classical computers .
several proposals for solid - state based _ quantum _ computers have been put forward , many of them in the context of superconductors @xcite .
as solid - state systems contain a macroscopic number of degrees of freedom , they are very sensitive to decoherence . mastering and
optimizing this decoherence is a formidable task and requires deep understanding of the physical system under investigation .
recent experimental success @xcite suggests that this task can in principle be performed . in this contribution
, we are going to study decoherence of superconducting qubits coupled to an....
And you have already written the first three sentences of the full article: superconducting qubits @xcite are very well suited for the task of solid - state quantum computation , because two of the most obvious decoherence sources in solid - state systems are supressed : quasiparticle excitations experience an energy gap and phonons are frozen out at low temperatures @xcite .
the computational hilbert space is engineered using josephson tunnel junctions that are characterized by two competing energy scales : the josephson coupling of a junction with critical current @xmath0 , @xmath1 , and the charging energy @xmath2 of a single cooper pair on the geometric capacitance @xmath3 of the junction . here
@xmath4 is the superconducting flux quantum ..
Please generate the next two sentences of the article | there is a variety of qubit proposals classified by the ratio of this energies .
whereas another contribution in this volume @xcite focuses on the case of charge qubits , @xmath5 , this contribution is motivated by flux qubit physics , @xmath6 |
5,450 | Suppose that you have an abstract for a scientific paper: given a coxeter system @xmath0 equipped with an involutive automorphism @xmath1 , the set of _ twisted identities _
is @xmath2 we point out how @xmath3 shows up in several contexts and prove that if there is no @xmath4 such that @xmath5 is of odd order greater than @xmath6 , then the bruhat order on @xmath3 is a graded poset with rank function @xmath7 given by halving the coxeter length . under the same condition , it is shown that the order complexes of the open intervals either are pl spheres or @xmath8-acyclic . in the general case
, contractibility is shown for certain classes of intervals .
furthermore , we demonstrate that sometimes these posets are not graded . for the poincar series of @xmath3 , i.e. its generating function with respect to @xmath7 , a factorisation phenomenon is discussed . .
And you have already written the first three sentences of the full article: let @xmath0 be a coxeter system with an involutive automorphism @xmath1 .
a _ twisted identity _ is an element of the form @xmath9 for @xmath10 . in other words ,
the set @xmath3 of twisted identities is the orbit of the identity element under the twisted conjugation action of @xmath11 on itself ..
Please generate the next two sentences of the article | our terminology appeared in @xcite and stems from the fact that when @xmath12 , the only twisted identity is the identity element @xmath13 .
as will be demonstrated in section [ se : motivation ] , the study of @xmath3 is motivated by its appeareance in a variety of situations . |
5,451 | Suppose that you have an abstract for a scientific paper: new @xmath0 photometry and optical spectroscopy of the type iip supernova 2004dj in ngc 2403 , obtained during the first year since discovery , are presented .
the progenitor cluster , sandage 96 , is also detected on pre - explosion frames .
the light curve indicates that the explosion occured about 30 days before discovery , and the plateau phase lasted about @xmath1 days after that .
the plateau - phase spectra have been modelled with the @xmath2 spectral synthesis code using h , na i , ti ii , sc ii , fe ii and ba ii lines . the sn distance is inferred from the expanding photosphere method ( epm ) and the standard candle method ( scm ) applicable for sne iip .
they resulted in distances that are consistent with each other as well as earlier cepheid- and tully - fisher distances .
the average distance , @xmath3 mpc is proposed for sn 2004dj and ngc 2403 .
the nickel mass produced by the explosion is estimated as @xmath4 .
the sed of the progenitor cluster is reanalysed by fitting population synthesis models to our observed @xmath0 data supplemented by @xmath5 and @xmath6 magnitudes from the literature .
the @xmath7-minimization revealed a possible `` young '' solution with cluster age @xmath8 myr , and an `` old '' solution with @xmath9 - @xmath10 myr .
the `` young '' solution would imply a progenitor mass @xmath11 , which is higher than the previously detected progenitor masses for type ii sne .
[ firstpage ] stars : evolution supernovae : individual ( sn 2004dj ) galaxies : individual ( ngc 2403 ) .
And you have already written the first three sentences of the full article: type ii supernovae ( sne ) emerge from shock - driven explosion of massive ( @xmath12 ) stars initiated by core collapse @xcite .
in particular , plateau type ii sne ( sne iip ) result from core collapse of supergiants that have massive hydrogen - rich envelope .
the light curves of sne iip are characterized by a constant luminosity plateau lasting about 80 - 120 days after explosion @xcite ..
Please generate the next two sentences of the article | recently , the progenitors of a few sne iip have been directly identified on pre - explosion images @xcite , revealing that these are @xmath13 supergiants , close to the low - mass theoretical limit of the core collapse process .
sn 2004dj in ngc 2403 is an outstanding sn discovered by itagaki @xcite on july 31 , 2004 ( jd 2453218 ) , because it is one of the brightest and closest supernova observed ever . |
5,452 | Suppose that you have an abstract for a scientific paper: one century after einstein s work , brownian motion still remains both a fundamental open issue and a continous source of inspiration for many areas of natural sciences .
we first present a discussion about stochastic and deterministic approaches proposed in the literature to model the brownian motion and more general diffusive behaviours .
then , we focus on the problems concerning the determination of the microscopic nature of diffusion by means of data analysis . finally , we discuss the general conditions required for the onset of large scale diffusive motion . * brownian motion ( bm ) played a fundamental role in the development of molecular theory of matter , statistical mechanics and stochastic processes .
remarkably , one century after einstein s work , bm is still at the origin of scientific discussions as testified by a recent experiment performed to detect a trace of deterministic chaotic sources on macroscopic diffusion .
several authors , which discussed the results of such an experiment , argued that the possibility to discern experimentally between a deterministic chaotic and noisy dynamics , at the microscopic level , is severely limited by subtle technical and conceptual points .
however , the remarks raised by the scientific community have gone over the criticism and have led to a deeper understanding of the role of chaos in the diffusion . * after a short historical introduction to bm , we focus on the dynamical conditions to observe macroscopic diffusion .
in particular , we discuss the technical and conceptual limits in distinguishing , by means of data analysis , the deterministic or stochastic nature of diffusion .
a main tool for that is the @xmath0-entropy .
part of the discussion is devoted to the problem of macroscopic diffusion in deterministic non - chaotic dynamics . .
And you have already written the first three sentences of the full article: at the beginning of the twentieth century , the atomistic theory of matter was not yet fully accepted by the scientific community .
while searching for phenomena that would prove , beyond any doubt , the existence of atoms , einstein realized that `` _ ... according to the molecular - kinetic theory of heat , bodies of microscopically - visible size suspended in a liquid will perform movements of such magnitude that they can be easily observed in a microscope ... _ '' , as he wrote in his celebrated paper in 1905 @xcite . in this work ,
devoted to explain the irregular motion of browinan particles on theoretical grounds , einstein argued that the motion of these small bodies has a diffusive character ..
Please generate the next two sentences of the article | moreover , he discovered an important relation involving the diffusion coefficient @xmath1 , the fluid viscosity @xmath2 , the particles radius @xmath3 ( having assumed spherical particles ) , avogadro s number @xmath4 , the temperature @xmath5 and the gas constant @xmath6 : @xmath7 this relation can be employed , and actually had been , to determine experimentally the avogadro s number @xcite .
indeed , the diffusion coefficient can be measured by monitoring the growth , with time @xmath8 , of the particle displacement @xmath9 , which is expected to behave as @xmath10 einstein relation ( [ diff ] ) , that may be seen as the first example of the fluctuation - dissipation theorem @xcite , allowed for the determination of avogadro s number and gave one of the ultimate evidences of the existence of atoms . |
5,453 | Suppose that you have an abstract for a scientific paper: we consider a generalized version of knuth s parking problem , in which caravans consisting of a random number of cars arrive at random on the unit circle .
then each car turns clockwise until it finds a free space to park . extending a recent work by chassaing and louchard @xcite
, we relate the asymptotics for the sizes of blocks formed by occupied spots with the dynamics of the additive coalescent . according to the behavior of the caravan s size tail distribution ,
several qualitatively different versions of eternal additive coalescent are involved .
* keywords : * parking problem , additive coalescent , bridges with exchangeable increments . *
m.s.c .
code : * 60f17 , 60j25 . .
And you have already written the first three sentences of the full article: the original parking problem of knuth can be stated as follows . consider a parking lot with @xmath0 spaces , identified with the cyclic group @xmath1 .
initially the parking lot is empty , and @xmath2 cars in a queue arrive one by one .
car @xmath3 tries to park on a uniformly distributed space @xmath4 among the @xmath0 possible , independently of other cars , but if the space is already occupied , then it tries places labeled @xmath5 until it finally finds a free spot to park ..
Please generate the next two sentences of the article | as cars arrive , blocks of consecutive occupied spots are forming .
it appears that a _ phase transition _ occurs at the stage where the parking lot is almost full , more precisely when the number of free spots is of order @xmath6 . |
5,454 | Suppose that you have an abstract for a scientific paper: we introduce the voronoi functional of a triangulation of a finite set of points in the euclidean plane and prove that among all geometric triangulations of the point set , the delaunay triangulation maximizes the functional . this result
neither extends to topological triangulations in the plane nor to geometric triangulations in three and higher dimensions . .
And you have already written the first three sentences of the full article: the _ voronoi diagram _ of points @xmath0 in @xmath1-dimensional euclidean space decomposes @xmath2 into @xmath3 convex polyhedra , called _
voronoi domains_. the domain of @xmath4 is the set of points @xmath5 for which @xmath4 minimizes the euclidean distance : @xmath6 for points in general position , the geometrically realized nerve ( the straight - line dual in @xmath7 ) decomposes the convex hull of the points into simplices , called the _
delaunay triangulation_. it is a particular _ geometric triangulation _ of the points , which is a simplicial complex whose vertices are the given points and whose underlying space is convex ..
Please generate the next two sentences of the article | delaunay triangulations are used in numerous applications and often preferred over other geometric triangulations .
the question arises why the delaunay triangulation is better than others . in the plane , |
5,455 | Suppose that you have an abstract for a scientific paper: glueballs are particles whose valence degrees of freedom are gluons and therefore in their description the gauge field plays a dominant role .
we review recent results in the physics of glueballs with the aim set on phenomenology and discuss the possibility of finding them in conventional hadronic experiments and in the quark gluon plasma . in order to describe their properties
we resort to a variety of theoretical treatments which include , lattice qcd , constituent models , ads / qcd methods , and qcd sum rules .
the review is supposed to be an informed guide to the literature .
therefore , we do not discuss in detail technical developments but refer the reader to the appropriate references . .
And you have already written the first three sentences of the full article: quantum chromodynamics ( qcd ) is the theory of the hadronic interactions .
it is an elegant theory whose full non perturbative solution has escaped our knowledge since its formulation more than 30 years ago.@xcite the theory is asymptotically free@xcite and confining.@xcite a particularly good test of our understanding of the nonperturbative aspects of qcd is to study particles where the gauge field plays a more important dynamical role than in the standard hadrons . in particular glueballs , bound states of gluons , represent such a scenario .
the glueball spectrum has attracted much attention since the early days of qcd.@xcite the interest in this subject is related to the significant progress in the understanding of the properties of such states within qcd , as well as , in the new possibilities for their identification in modern experiments ..
Please generate the next two sentences of the article | historically the investigation of the glueball properties started in the bag model by jaffe and johnson.@xcite they found many glueball states with different quantum numbers lying in the mass interval 1000 - 2000 mev .
they emphasized that one should expect rather small widths for such states because their decays in conventional hadrons violate the okubo - zweig - iizuka ( ozi ) rule.@xcite after this pioneering work the study of glueballs was carried out by using various versions of constituent models , by exploiting the qcd sum rule approach and by performing lattice qcd calculations . |
5,456 | Suppose that you have an abstract for a scientific paper: we report interferometric mapping of the bipolar pre - planetary nebula iras08005 - 2356 ( i08005 ) with an angular - resolution of @xmath015 , using the submillimeter array ( sma ) , in the @xmath1co j=21 , 32 , @xmath2co j=21 and sio j=54 ( v=0 ) lines .
single - dish observations , using the smt 10-m , were made in these lines as well as in the co j=43 and sio j-65 ( v=0 ) lines .
the lines profiles are very broad , showing the presence of a massive ( @xmath3 ) , extreme high - velocity outflow ( @xmath4 ) directed along the nebular symmetry axis derived from the hst imaging of this object .
the outflow s scalar momentum far exceeds that available from radiation pressure of the central post - agb star , and it may be launched from an accretion disk around a main - sequence companion .
we provide indirect evidence for such a disk from its previously published , broad h@xmath5 emission profile , which we propose results from ly@xmath6 emission generated in the disk followed by raman - scattering in the innermost regions of a fast , neutral wind . .
And you have already written the first three sentences of the full article: following the ejection of half or more of their mass via isotropic , slowy expanding winds , agb stars evolve into planetary nebulae ( pne ) , which , surprisingly show a diverse range of aspherical ( e.g. , bipolar and multipolar ) morphologies ( e.g. , sahai & trauger 1998 , sahai , morris & villar 2011a ) . studies of pre - planetary nebulae ( ppns ) , objects in transition between the agb and planetary nebula ( pn ) evolutionary phases , are critical for characterising the physical processes responsible for this dramatic transformation . sahai & trauger ( 1998 ) proposed that fast collimated outflows or jets , operating during the ppn and/or very late agb phase , are the primary agents for the dramatic change in the mass - loss geometry and dynamics during the agb - to - pn evolutionary phase .
however , the physical mechanism for producing these fast outflows remains a mystery .
high - angular - resolution interferometric ( sub)millimeter - wave observations are the best way to quantitatively probe the fast outflow s dynamics and energetics crucial information for theoretical models ( e.g. , akashi & soker 2013 ) , and detailed numerical hydrodynamical simulations ( e.g. , lee & sahai 2003 , balick et al . 2013 ) , for pn shaping ..
Please generate the next two sentences of the article | such observations have resulted in the discovery of a handful of extreme - outflow " ppns objects in which the molecular outflows reach speeds in excess of @xmath0100 , e.g. , boomerang nebula ( sahai et al . 2013 ) , iras22036 + 5306 ( sahai et al .
2006 ) , iras19374 + 2359 ( s ' |
5,457 | Suppose that you have an abstract for a scientific paper: we report on results of a search for the decay mode @xmath0 conducted by the e162 experiment at kek .
we observed no events and set a 90% confidence level upper limit of @xmath1 for its branching ratio .
this is the first published experimental result on this decay mode .
1em _ pacs : _ 13.20.eb , 14.40.aq , , , , , , , , , , , .
And you have already written the first three sentences of the full article: chiral perturbation theory ( @xmath2pt ) is a very powerful tool to describe various @xmath3 decays in which long distance contributions are expected to dominate . for example , the decay mode @xmath4 has been observed recently , and compared with @xmath2pt @xcite .
the measured branching ratio and @xmath5 momentum spectrum are found to be consistent with the predictions , after fitting one free parameter contained in the theory .
the neutral counterpart , @xmath6 , is another decay mode , where detailed studies have been performed . in this case ,.
Please generate the next two sentences of the article | the lowest order @xmath7 calculation @xcite does not reproduce the measured branching ratio @xcite . extending the calculation to the next - to - leading order @xmath8 @xcite , and adding a vector meson contribution @xcite
, the prediction is now in good agreement with the branching ratio as well as distinct @xmath9 spectrum . |
5,458 | Suppose that you have an abstract for a scientific paper: standard density functional approximations often give questionable results for odd - electron radical complexes , with the error typically attributed to self - interaction . in density corrected density functional theory ( dc - dft ) , certain classes of density functional theory calculations are significantly improved by using densities more accurate than the self - consistent densities .
we discuss how to identify such cases , and how dc - dft applies more generally . to illustrate , we calculate potential energy surfaces of ho@xmath0cl@xmath1 and ho@xmath0h@xmath2o complexes using various common approximate functionals , with and without this density correction .
commonly used approximations yield wrongly shaped surfaces and/or incorrect minima when calculated self consistently , while yielding almost identical shapes and minima when density corrected .
this improvement is retained even in the presence of implicit solvent .
_ c # 1*#1 * .
And you have already written the first three sentences of the full article: odd - electron radical complexes like ho@xmath0cl@xmath3 and ho@xmath0h@xmath2o are of tremendous importance throughout chemistry and in related fields , such as in radiation chemistry , atmospheric chemistry , environmental chemistry , and cell biology@xcite . in particular , the behavior of anions in droplets is of critical importance to understanding atmospheric chemistry .
common sense suggests that anions are less perfectly screened near a water - air interface , and so have lower concentration there .
recent classical molecular dynamics ( md ) simulations have shown just the opposite@xcite , creating considerable controversy on this point ..
Please generate the next two sentences of the article | since anions are strongly quantum mechanical , it is logical to check traditional md simulations , using only classical force fields , against _ ab initio _ molecular dynamics ( aimd ) calculations , which use density functional theory ( dft ) to generate the potential energy surfaces ( pes ) .
unfortunately , standard dft approximations have issues for such systems@xcite . |
5,459 | Suppose that you have an abstract for a scientific paper: we investigate the effect of dephasing / decoherence on quantum transport through open chaotic ballistic conductors in the semiclassical limit of small fermi wavelength to system size ratio , @xmath0 .
we use the trajectory - based semiclassical theory to study a two - terminal chaotic dot with decoherence originating from : ( i ) an external closed quantum chaotic environment , ( ii ) a classical source of noise , ( iii ) a voltage probe , i.e. an additional current - conserving terminal .
we focus on the pure dephasing regime , where the coupling to the external source of dephasing is so weak that it does not induce energy relaxation .
in addition to the universal algebraic suppression of weak localization , we find an exponential suppression of weak - localization @xmath1 $ ] , with the dephasing rate @xmath2 .
the parameter @xmath3 depends strongly on the source of dephasing . for a voltage probe ,
@xmath3 is of order the ehrenfest time @xmath4 $ ] .
in contrast , for a chaotic environment or a classical source of noise , it has the correlation length @xmath5 of the coupling / noise potential replacing the fermi wavelength @xmath6 .
we explicitly show that the fano factor for shot noise is unaffected by decoherence .
we connect these results to earlier works on dephasing due to electron - electron interactions , and numerically confirm our findings . .
And you have already written the first three sentences of the full article: electronic systems in the mesoscopic regime are ideal testing - grounds for investigating the quantum - to - classical transition from a microscopic coherent world ( where quantum interference effects prevail ) to a macroscopic classical world @xcite . on one hand , their size is intermediate between macroscopic and microscopic ( atomic ) systems , on the other hand , today s experimental control over their design and precision of measurement allows one to investigate them in regimes ranging from almost fully coherent to purely classical @xcite
. the extent to which quantum coherence is preserved in these systems is usually determined by the ratio @xmath7 of the dephasing time @xmath8 to some relevant classical time scale @xmath9 .
for instance , @xmath9 can be the traversal time through one arm of a two - path interferometer @xcite , or the average dwell time spent inside a quantum dot @xcite . in a given experimental set - up ,.
Please generate the next two sentences of the article | @xmath8 can often be tuned from @xmath10 ( quantum coherent regime ) to @xmath11 ( purely classical regime ) by varying externally applied voltages or the temperature of the sample .
coherent effects abound in mesoscopic physics , the most important of them being weak - localization , universal conductance fluctuations and aharonov - bohm interferences in transport , as well as persistent currents @xcite . |
5,460 | Suppose that you have an abstract for a scientific paper: n - body algorithms for long - range unscreened interactions like gravity belong to a class of highly irregular problems whose optimal solution is a challenging task for present - day massively parallel computers . in this paper
we describe a strategy for optimal memory and work distribution which we have applied to our parallel implementation of the barnes & hut ( 1986 ) recursive tree scheme on a cray t3d using the craft programming environment .
we have performed a series of tests to find an _
optimal data distribution _ in the t3d memory , and to identify a strategy for the _ dynamic load balance _ in order to obtain good performances when running large simulations ( more than 10 million particles ) .
the results of tests show that the step duration depends on two main factors : the data locality and the t3d network contention .
increasing data locality we are able to minimize the step duration if the closest bodies ( direct interaction ) tend to be located in the same pe local memory ( contiguous block subdivison , high granularity ) , whereas the tree properties have a fine grain distribution . in a very large simulation , due to network contention ,
an unbalanced load arises . to remedy this
we have devised an automatic work redistribution mechanism which provided a good dynamic load balance at the price of an insignificant overhead . , , , , , and .
And you have already written the first three sentences of the full article: n - body simulations are one of the most important tools by which contemporary theoretical cosmologists try to investigate the evolution of the large scale structure of the universe . due to the long - range nature of the gravitational force ,
the number of particles required to reach a significant mass resolution is a few orders of magnitude larger than those allowed even by present - day state - of - the - art massively parallel supercomputers ( hereafter mpp ) .
work- and data - sharing programming techniques are customary tools exploited in the development of many parallel implementations of the n - body problem @xcite @xcite @xcite ..
Please generate the next two sentences of the article | the most popular algorithms are generally based on grid methods like the @xmath0 .
the main problem with this method lies in the fact that the grid has typically a fixed mesh size , while the cosmological problem is inherently highly irregular , because a highly clustered large - scale structure develops starting from a nearly homogeneous initial distribution . on the other hand |
5,461 | Suppose that you have an abstract for a scientific paper: at low metallicity , b - type stars show lower loss of mass and , therefore , angular momentum so that it is expected that there are more be stars in the magellanic clouds than in the milky way .
however , till now , searches for be stars were only performed in a very small number of open clusters in the magellanic clouds . using the eso / wfi in its slitless spectroscopic mode
, we performed a halpha survey of the large and small magellanic cloud .
eight million low - resolution spectra centered on halpha were obtained . for their automatic analysis
, we developed the album code . here , we present the observations , the method to exploit the data and first results for 84 open clusters in the smc .
in particular , cross - correlating our catalogs with ogle positional and photometric data , we classified more than 4000 stars and were able to find the b and be stars in them .
we show the evolution of the rates of be stars as functions of area density , metallicity , spectral type , and age . .
And you have already written the first three sentences of the full article: emission line stars ( els ) range from young to evolved stars ( ttauri , herbig ae / be , wr , planetary nebulae , etc ) , from hot to cool stars ( classical be star , oe , supergiant star , mira ceti , flare stars , etc ) . among the els , here ,
we focus on the classical be stars .
they are non - supergiant b type stars , which have displayed at least once emission lines in their spectra , mainly in the balmer series of the hydrogen ..
Please generate the next two sentences of the article | the emission lines come from a circumstellar decretion disk formed by episodic matter ejection of the central star .
it appears that the be phenomenon is related to fast rotation and probably additional properties such as non - radial pulsation or magnetic fields . for a comprehensive review of |
5,462 | Suppose that you have an abstract for a scientific paper: the anomalous hall effect ( ahe ) is a consequence of spin - orbit coupling in a ferromagnetic metal and related primarily to density - matrix response to an electric field that is off - diagonal in band index .
for this reason disorder contributions to the ahe are difficult to treat systematically using a semi - classical boltzmann equation approach , even when weak localization corrections are disregarded . in this article
we explicitly demonstrate the equivalence of an appropriately modified semiclassical transport theory which includes anomalous velocity and side jump contributions and microscopic kubo - streda perturbation theory , with particular unconventional contributions in the semiclassical theory identified with particular feynman diagrams when calculations are carried out in a band - eigenstate representation .
the equivalence we establish is verified by explicit calculations for the case of the two - dimensional ( 2d ) dirac model hamiltonian relevant to graphene . .
And you have already written the first three sentences of the full article: in spite of its long history as a basic ferromagnetic metal characterization tool , the theory of the anomalous hall effect ( ahe ) continues to be a subject of confusion and debate.@xcite theoretical descriptions of the dc ahe invariably involve long and complex calculations and usually do not lead to simple general results with transparent interpretations .
theories of the ahe normally focus on particular simple model hamiltonians , and ignore interactions apart from mean - field exchange potentials that encode magnetic order . even with these simplifications , the ahe _ problem _ tends to be difficult because the effect usually follows mainly from density - matrix linear response that is off - diagonal in bloch state band indices , _
i.e. _ from induced interband coherence rather than simply from changes in bloch state occupations ..
Please generate the next two sentences of the article | farraginous theoretical results have followed from the application of different methods to the same models .
rigorous approaches based on green s function techniques , like the keldysh or kubo - streda formalisms , have the advantage of being systematic but can be technically more difficult to implement and are often not physically transparent . |
5,463 | Suppose that you have an abstract for a scientific paper: we prove explicit approximation hardness results for the graphic tsp on cubic and subcubic graphs as well as the new inapproximability bounds for the corresponding instances of the ( 1,2)-tsp .
the proof technique uses new modular constructions of simulating gadgets for the restricted cubic and subcubic instances .
the modular constructions used in the paper could be also of independent interest . .
And you have already written the first three sentences of the full article: we study the traveling salesman problem in the shortest path metric completion ( _ graphic tsp _ ) of cubic as well as subcubic graphs .
these two cases played a crucial role in some recent developments on _ graphic tsp _
@xcite , @xcite , @xcite , @xcite , @xcite ) ..
Please generate the next two sentences of the article | we shed some light on their inapproximability status and prove explicit approximation hardness bounds of 1153/1152 for the cubic graphic tsp and 685/684 for the subcubic case .
we design new @xmath0-regular gadget amplifier construction yielding the above bounds , and establish also new inapproximability bounds for the cubic and subcubic instances of the ( 1,2)-tsp of 1141/1140 and 673/672 , respectively . |
5,464 | Suppose that you have an abstract for a scientific paper: in this paper we explore how recent technologies can improve the security of optical networks .
in particular , we study how to use quantum key distribution ( qkd ) in common optical network infrastructures and propose a method to overcome its distance limitations .
qkd is the first technology offering information theoretic secret - key distribution that relies only on the fundamental principles of quantum physics .
point - to - point qkd devices have reached a mature industrial state ; however , these devices are severely limited in distance , since signals at the quantum level ( e.g. single photons ) are highly affected by the losses in the communication channel and intermediate devices . to overcome this limitation , intermediate nodes ( i.e. repeaters )
are used .
both , quantum - regime and trusted , classical , repeaters have been proposed in the qkd literature , but only the latter can be implemented in practice . as a novelty ,
we propose here a new qkd network model based on the use of not fully trusted intermediate nodes , referred as _
weakly trusted repeaters_. this approach forces the attacker to simultaneously break several paths to get access to the exchanged key , thus improving significantly the security of the network .
we formalize the model using network codes and provide real scenarios that allow users to exchange secure keys over metropolitan optical networks using only passive components .
moreover , the theoretical framework allows to extend these scenarios not only to accommodate more complex trust constraints , but also to consider robustness and resiliency constraints on the network .
network coding ; quantum key distribution ; passive optical networks ; trusted repeaters . .
And you have already written the first three sentences of the full article: optical network design has evolved over time to meet different challenges : high bandwidth , deployment flexibility , multiuser requirements , etc .
other characteristics were considered secondary at the time and added later , as their need or convenience became more pressing .
security has been one of these secondary requirements ..
Please generate the next two sentences of the article | it was usually taken for granted in optical networks due to the technical difficulty of spying the signal carried by an optical fiber @xcite .
however , technological advances and transformations in the structure of the network changed the panorama and this is no longer true @xcite . on one hand , sensitive detectors and small transponders are nowadays able to perform , at a fraction of the cost and size , the operations that previously needed rack - sized equipment . on the other , certain network architectures simply does not lend itself to security @xcite . as an example , downstream signals in a gigabit passive optical network ( gpon ) arrive to all users and are only dismissed by a well behaved optical network terminator ( ont ) . |
5,465 | Suppose that you have an abstract for a scientific paper: we find the quasinormal modes of the charged scalar and dirac fields in the background of the rotating charged black holes , described by the kerr - newman - de sitter solution .
the dependence of the quasinormal spectrum upon the black hole parameters mass @xmath0 , angular momentum @xmath1 , charge @xmath2 , as well as on values of the @xmath3-term and a field charge @xmath4 is investigated .
special attention is given to the near extremal limit of the black hole charge .
in particular , we find that for both scalar and dirac fields , charged perturbations decay quicker for @xmath5 and slower for @xmath6 for values of black holes charge @xmath2 less than than some threshold value , which is close to the extremal value of charge and depend on parameters of the black holes . .
And you have already written the first three sentences of the full article: quasinormal spectrum of black holes has been extensively investigated during recent years for a great variety of black hole backgrounds and fields , because it is an important characteristic for observation of the gravitational waves @xcite , stability analysis @xcite , ads / cft calculations of temperature green functions @xcite .
special attention has been paid to perturbations of a scalar field @xcite , as a simplest model , when the influence of the spin of the field is neglected . when one considers the charged black hole , the scalar electrodynamic can successfully model the interaction of the charged field with the electromagnetic background of the black hole .
therefore the calculation of the quasinormal modes of charged fields , initiated in @xcite for charged scalar field in the reissner - nordstm and dilaton backgrounds , was continued in the further research @xcite . in particular , in @xcite.
Please generate the next two sentences of the article | the quasinormal modes of the massive charged scalar field were found with the wkb accuracy . in @xcite and @xcite
it was shown that the quasinormal modes , corresponding to the charged scalar field , decay quicker than those of the neutral field unless the black hole charge is larger than some large near extremal value . |
5,466 | Suppose that you have an abstract for a scientific paper: periods of parallel exterior forms define natural coordinates on the deformation space of complete affine structures on the two - torus .
these coordinates define a differentiable structure on this deformation space , under which it is diffeomorphic to @xmath0 .
the action of the mapping class group of @xmath1 is equivalent in these coordinates with the standard linear action of @xmath2 on @xmath0 . .
And you have already written the first three sentences of the full article: conformal structures on the 2-torus @xmath1 ( elliptic curves ) are classified by a moduli space , which is the quotient of the upper half - plane @xmath3 by the action of the modular group @xmath2 by linear fractional transformations .
in other words , equivalence classes of elliptic curves correspond to orbits of @xmath2 on @xmath3 .
since @xmath4 is not a smooth manifold , it is often easier to study properties of elliptic curves in terms of the _ action _ of @xmath2 on the smooth manifold @xmath3 ..
Please generate the next two sentences of the article | this note concerns the analogous question for _ complete affine structures _ on @xmath1 .
complete affine structure _ on a manifold @xmath5 is a representation of @xmath5 as the quotient of affine space @xmath6 by a discrete group of affine transformations . |
5,467 | Suppose that you have an abstract for a scientific paper: a scheme for an atomic beam quantum self - eraser is presented .
the proposal is based on time reversal invariance on a quantum optical ramsey fringes experiment , where a realization of complementarity for atomic coherence can be achieved .
it consists of two high finesse resonators that are pumped and probed by the same atom .
this property relates quantum erasing with time reversal symmetry , allowing for a full quantum erasing of the which - way information stored in the cavity fields .
the outlined scheme also prepares and observes a non - local state in the fields of the resonators : a coherent superposition between correlated states of macroscopically separated quantum systems .
the proposed scheme emphasizes the role of entanglement swapping in delayed - choice experiments .
finally , we show that the quantum self - eraser violates temporal bell inequalities and analyze the relation between this violation and the erasability of which - way information . .
And you have already written the first three sentences of the full article: the complementarity principle has traditionally been addressed in order to illustrate the role of observer in quantum mechanics .
one of the most intriguing aspect of the issue is the possibility of delayed - choice experiments @xcite .
according to it , the experimenter may decide for instance to display wavelike aspects of an atomic system , long after it has been forced into a particle - like behavior @xcite ..
Please generate the next two sentences of the article | if the atomic state is entangled with a memory system available to the observer , i.e. , a which - way detector ( wwd ) , the experimenter may decide to postpone his decision even after the atom has been detected .
interference fringes can be recovered , provided the which - way information ( wwi ) is erased from the wwd @xcite . |
5,468 | Suppose that you have an abstract for a scientific paper: an alternative to the conventional see - saw mechanism is proposed to explain the origin of small neutrino masses in supersymmetric theories .
the masses and couplings of the right - handed neutrino field are suppressed by supersymmetry breaking , in a way similar to the suppression of the higgs doublet mass , @xmath0 .
new mechanisms for light majorana , dirac and sterile neutrinos arise , depending on the degree of suppression .
superpartner phenomenology is greatly altered by the presence of weak scale right - handed sneutrinos , which may have a coupling to a higgs boson and a left - handed sneutrino .
the sneutrino spectrum and couplings are quite unlike the conventional case - the lightest sneutrino can be the dark matter and predictions are given for event rates at upcoming halo dark matter direct detection experiments .
higgs decays and search strategies are changed .
copious higgs production at hadron colliders can result from cascade decays of squarks and gluinos .
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1#1 ucb - pth-00/18 + lbnl-46180 + hep - ph/0006312 + + .5 in * small neutrino masses + from supersymmetry breaking * .50 in nima arkani - hamed , lawrence hall , hitoshi murayama , david smith and neal weiner 0.05 in _ department of physics + university of california , berkeley , california 94720 _ 0.05 in and 0.05 in _ theoretical physics group + ernest orlando lawrence berkeley national laboratory + university of california , berkeley , california 94720 _ .5 in .5 in .
And you have already written the first three sentences of the full article: why are the neutrinos much lighter than the charged leptons , but not absolutely massless ? it is universally recognized that this can be simply and elegantly understood in an @xmath1 effective theory .
the most general , gauge - invariant interactions of dimension less than six , which can lead to masses for the known leptons from the vacuum expectation value ( vev ) of a higgs doublet , are : @xmath2 where @xmath3 and @xmath4 are the lepton doublet and singlet fields , and @xmath5 is the higgs doublet .
the dimensionless matrix of yukawa couplings , @xmath6 , has a hierarchy of eigenvalues to describe the masses of the charged leptons ..
Please generate the next two sentences of the article | such a hierarchy could result by promoting the couplings to fields , @xmath7 , which acquire vevs to sequentially , spontaneously break the flavor symmetry @xmath8 .
such a flavor symmetry will also result in a certain structure for the neutrino mass matrix via @xmath9 . |
5,469 | Suppose that you have an abstract for a scientific paper: the dark energy survey ( des ) is a project with the goal of building , installing and exploiting a new 74 ccd - camera at the blanco telescope , in order to study the nature of cosmic acceleration .
it will cover 5000 square degrees of the southern hemisphere sky and will record the positions and shapes of 300 million galaxies up to redshift 1.4 .
the survey will be completed using 525 nights during a 5-year period starting in 2012 .
about o(1 tb ) of raw data will be produced every night , including science and calibration images .
the des data management system has been designed for the processing , calibration and archiving of these data .
it is being developed by collaborating des institutions , led by ncsa . in this contribution
, we describe the basic functions of the system , what kind of scientific codes are involved and how the data challenge process works , to improve simultaneously the data management system algorithms and the science working group analysis codes . .
And you have already written the first three sentences of the full article: the dark energy survey data management ( desdm ) is the part of the dark energy survey project @xcite that will transfer , process and distribute the data generated by survey s camera decam @xcite .
desdm is a large , scalable system led by the national center for supercomputing applications at the university of illinois at urbana - champaign ( ncsa / uiuc ) consisting of : 1 . an archive system for different levels of data .
2 . scientific codes to process raw data ..
Please generate the next two sentences of the article | 3 . database to support calibration , provenance and data analyses .
4 . web portals providing process control and easy access to images and catalogs . 5 . hardware platforms for execution and storage . as of august 2011 , |
5,470 | Suppose that you have an abstract for a scientific paper: integrable equations exhibit interesting conformal properties and can be written in terms of the so - called conformal invariants .
the most basic and important example is the kdv equation and the corresponding schwarz - kdv equation .
other examples , including the camassa - holm equation and the associated camassa - holm equation are investigated in this paper .
it is shown that the bcklund transform is related to the conformal properties of these equations .
some particular solutions of the associated camassa - holm equation are discussed also . *
pacs : * 05.45.yv , 02.30.ik * key words : * schwarz derivative , conformal invariants , lax pair , integrable systems , solitons , positons , negatons . * conformal properties and bcklund transform for the associated camassa - holm equation + * * rossen ivanov@xmath0 * -.3 cm c -1 cm @xmath1_school of mathematics , trinity college , _
+ _ dublin 2 , ireland _ + _ tel : + 353 - 1 - 608 2898 _ + _ fax : + 353 - 1- 608 2282 _
+ + _ @xmath0e - mail : [email protected]_ + + -.8 cm .
And you have already written the first three sentences of the full article: integrable equations exhibit many extraordinary properties like infinitely many conservation laws , multi- hamiltonian structures , soliton solutions etc .
many integrable equations in 1 + 1 dimensions like kdv , mkdv , harry - dym , boussinesq equations possess interesting conformal properties as well @xcite .
they can be written in terms of the so - called independent conformal invariants of the function @xmath2 : [ eq1 ] p_1 & = & + p_2 & = & \{;x}- + here @xmath3 denotes the schwarz derivative ..
Please generate the next two sentences of the article | a quantity is called conformally invariant if it is invariant under the mbius transformation [ eq2 ] & & , .
for example , the kdv equation [ eq3 ] u_t+au_xxx+3uu_x=0 ( @xmath4 is a constant ) can be written in a schwarzian form , i.e. in terms of the conformal invariants ( [ eq1 ] ) as @xmath5 or [ eq3b ] + a\{;x}=0 where [ eq3a ] u = a\{;x}. the kdv and camassa - holm ( ch ) @xcite equations arise also as equations of the geodesic flow for the @xmath6 and @xmath7 metrics correspondingly on the bott - virasoro group @xcite . |
5,471 | Suppose that you have an abstract for a scientific paper: in this contribution i review the present status and discuss some prospects for indirect detection of dark matter with gamma - rays .
thanks to the fermi large area telescope , searches in gamma - rays have reached sensitivities that allow to probe the most interesting parameter space of the weakly interacting massive particles ( wimp ) paradigm . this gain in sensitivity
is naturally accompanied by a number of detection claims or indications , the most recent being the claim of a line feature at a dark matter particle mass of @xmath0 130 gev at the galactic centre , a claim which requires confirmation from the fermi - lat collaboration and other experiments , for example hess ii or the planned gamma-400 satellite .
predictions for the next generation air cherenkov telescope , cherenkov telescope array ( cta ) , together with forecasts on future fermi - lat constraints arrive at the exciting possibility that the cosmological benchmark cross - section could be probed from masses of a few gev to a few tev .
consequently , non - detection would pose a challenge to the wimp paradigm , but the reached sensitivities also imply that optimistically a detection is in the cards .
+ address = oskar klein centre , physics department , stockholm university .
And you have already written the first three sentences of the full article: observations from galactic to cosmological scales leave little room to explanations for dark matter ( dm ) other than that it is provided by a new type of particle .
the most studied option for this particle is a weakly interacting massive particle ( wimp ) .
the reason for this is sometime referred to as the `` wimp miracle '' : for a particle of mass of the weak scale ( @xmath0100 gev ) , the annihilation cross section is given approximately by : @xmath1 and at the same time @xmath2 , from considering the relic density of a stable particle produced thermally in the early universe ..
Please generate the next two sentences of the article | wimps are searched for in a variety of ways : by particle production at accelerators , by searching for signals of nuclear recoils ( direct detection ) and last but not least by searching for a signal from secondary products of wimp annihilation or decay , in particular gamma - rays .
+ spectral signatures in gamma - rays can be classified in smoking gun signals and ambiguous signals . |
5,472 | Suppose that you have an abstract for a scientific paper: the infrared behaviour of qcd green s functions in landau gauge has been focus of intense study .
different non - perturbative approaches lead to a prediction in line with the conditions for confinement in local quantum field theory as spelled out in the kugo - ojima criterion .
detailed comparisons with lattice studies have revealed small but significant differences , however . but are nt we comparing apples with oranges when contrasting lattice landau gauge simulations with these continuum results ?
the answer is yes , and we need to change that .
we therefore propose a reformulation of landau gauge on the lattice which will allow us to perform gauge - fixed monte - carlo simulations matching the continuum methods of local field theory which will thereby be elevated to a truly non - perturbative level at the same time . *
landau gauge qcd : functional methods versus lattice simulations international conference on _ selected problems of modern theoretical physics _ ( spmtp08 ) , bogoliubov laboratory of theoretical physics , dubna , russia , 23 27 june , 2008 . ] * lorenz von smekal + _ centre for the subatomic structure of matter , school of chemistry and physics , + the university of adelaide , sa 5005 , australia _ .
And you have already written the first three sentences of the full article: the green s functions of qcd are the fundamental building blocks of hadron phenomenology @xcite .
their infrared behaviour is also known to contain essential information about the realisation of confinement in the covariant formulation of qcd , in terms of local quark and gluon field systems .
the landau gauge dyson - schwinger equation ( dse ) studies of refs ..
Please generate the next two sentences of the article | @xcite established that the gluon propagator alone does not provide long - range interactions of a strength sufficient to confine quarks .
this dismissed a widespread conjecture from the 1970 s going back to the work of marciano , pagels , mandelstam and others . |
5,473 | Suppose that you have an abstract for a scientific paper: the prompt optical flash recently detected accompanying grb990123 suggests that , for at least some grbs , @xmath0-ray emission is accompanied by prompt optical - uv emission with luminosity @xmath1 , where @xmath2 is the solid angle into which @xmath0-ray and optical - uv emission is beamed .
such an optical - uv flash can destroy dust _ in the beam _ by sublimation out to an appreciable distance , @xmath3 pc , and may clear the dust out of as much as @xmath4 of molecular cloud material on an apparent time scale of @xmath5 ten seconds .
detection of time dependent extinction on this time scale would therefore provide strong constraints on the grb source environment .
dust destruction implies that existing , or future , observations of not - heavily - reddened fireballs are not inconsistent with grbs being associated with star forming regions . in this case , however , if @xmath0-ray emission is highly beamed , the expanding fireball would become reddened on a @xmath51 week time scale .
if the optical depth due to dust beyond @xmath6 pc from the grb is @xmath7 , most of the uv flash energy is converted to infra - red , @xmath8 m , radiation with luminosity @xmath9 extending over an apparent duration of @xmath10 day .
dust infra - red emission may already have been observed in grb970228 and grb980326 , and may possibly explain their unusual late time behavior .
# 1#2 epsfbox 16 you need to input epsf ; i ll do it for you epsf = # 2 1 # 1 1 16cant open # 1 1 .
And you have already written the first three sentences of the full article: a prompt , 9-th magnitude , optical flash has recently been detected ( @xcite ) accompanying the gamma ray burst ( grb ) grb990123 .
the most natural explanation of this flash is emission from a reverse shock propagating into fireball ejecta shortly after it interacts with surrounding gas ( @xcite ) .
although optical - uv emission from the reverse shock accompanying , or following shortly after , the @xmath0-ray emission has been predicted ( @xcite ) based on the simplest fireball models for gamma - ray bursts ( grbs ) , the intensity of optical emission could not have been reliably predicted due to the uncertainty in reverse shock parameters ..
Please generate the next two sentences of the article | the observations of grb990123 suggest that the electron and magnetic field energy fractions in the reverse shock are similar to those in the forward shock propagating into the surrounding gas and producing the long term afterglow .
this in turn implies that strong optical flashes accompanying @xmath0-ray emission is a generic grb characteristic . |
5,474 | Suppose that you have an abstract for a scientific paper: we outline the extension of the globally chirally invariant @xmath0 linear sigma model with vector and axial - vector degrees of freedom to @xmath1 .
we present preliminary results concerning the scalar meson masses . .
And you have already written the first three sentences of the full article: the experimental data on kaons and other mesons containing strange quarks are both abundant and rather precise [ ] .
these particles are expected to play an important role in meson vacuum phenomenology and at non - zero temperatures , most notably in the restoration of the chiral symmetry that is spontaneously [ ] and explicitly [ ] broken in vacuum .
their structure - at least in the scalar sector - is ambiguous , as in the case of the non - strange mesons [ ] ..
Please generate the next two sentences of the article | + open questions regarding the strange mesons can be addressed , for example , within the linear sigma model [ ] , as has been done , e.g. , in ref .
[ ] . however , our approach is different in comparison to ref . [ ] in that our calculations are based on a globally chirally invariant @xmath1 lagrangian that contains the scalar and pseudoscalar but also vector and axial - vector degrees of freedom . in this paper |
5,475 | Suppose that you have an abstract for a scientific paper: einstein s theory of general relativity is the benchmark example for empirical success and mathematical elegance in theoretical physics .
however , in spite of being the most successfully tested theory in physics , there are strong theoretical and observational arguments for why general relativity should fail .
it is not a question of if , but rather a question of where and when ! i start by recounting the tremendous success in observational cosmology over the past three decades , that has led to the era of precision cosmology .
i will then summarize the pathologies in einstein s theory of gravity , as the cornerstone of standard cosmological model .
attempts to address these pathologies are either inspired by mathematical elegance , or empirical falsifiability .
here , i provide different arguments for why a falsifiable solution should violate lorentz symmetry , or revive `` gravitational aether '' .
deviations from einstein s gravity are then expected in : 1 ) cosmological matter - radiation transition , 2 ) neutron stars , 3 ) gravitomagnetic effect , 4 ) astrophysical black holes , and their potential connection to dark energy , and 5 ) early universe , where the predictions are ranked by their degree of robustness and falsifiability .
[ firstpage ] cosmology : theory gravitation dark energy neutron stars black hole physics
early universe .
And you have already written the first three sentences of the full article: observational cosmology has come a long way since the early days of being `` the science of two numbers '' .
the revolution could be traced back to the discovery of the cosmic microwave background ( cmb ) in 1964 by penzias and wilson @xcite , which won them the nobel prize in 1978 , and confirmed an earlier prediction of george gamow @xcite .
gamow had realized that the observed abundance of light nuclei can be explained from a hot uniform big bang phase , which is the inevitable beginning of an expanding universe in general relativity ..
Please generate the next two sentences of the article | however , it also predicts a relic background of radiation with @xmath0 k , which is reasonably close to the current observed value of @xmath1 k ( e.g. , * ? ? ?
gamow s triumph could be arguably thought of as the beginning of physical cosmology , as it bore all the marks of scientific method as we know it : a self - consistent theory is devised based on observations ( cosmic expansion and stellar elemental abundances ) , which makes predictions for completely different observables ( microwave background radiation ) , that are later confirmed . |
5,476 | Suppose that you have an abstract for a scientific paper: the effect of crystal lattice disorder on the conductivity and colossal magnetoresistance in la@xmath0ca@xmath1mno@xmath2 ( @xmath3 ) films has been examined .
the lattice defects are introduced by irradiating the film with high - energy ( @xmath4 mev ) electrons with a maximal fluence of about @xmath5 @xmath6 .
this comparatively low dose of irradiation produces rather small radiation damage in the films .
the number of displacements per atom ( dpa ) in the irradiated sample is about @xmath7
. nevertheless , this results in an appreciable increase in the film resistivity .
the percentage of the resistivity increase in the ferromagnetic metallic state ( below the curie temperature @xmath8 ) was much greater than that observed in the insulating state ( above @xmath8 ) .
at the same time irradiation has much less effect on @xmath8 or on the magnitude of the colossal magnetoresistance .
a possible explanation of such behavior is proposed .
# 1@xmath9#1 .
And you have already written the first three sentences of the full article: in recent years considerable attention has been focussed on the structural , magnetic and electron transport properties of perovskite oxides of the type r@xmath0a@xmath1mno@xmath2 ( where @xmath10 is a rare - earth element , @xmath11 a divalent alkaline - earth element ) .
this interest was caused by observation of an extremely large negative magnetoresistance in these compounds @xcite , which was called colossal magnetoresistance ( cmr ) .
along with fundamental importance for condensed matter physics , this phenomenon also offers applications in advanced technology ..
Please generate the next two sentences of the article | therefore the problem of cmr continues to be topical .
the doped manganites undergo a phase transition with decreasing temperature from a paramagnetic insulating state into a highly conducting ferromagnetic phase . |
5,477 | Suppose that you have an abstract for a scientific paper: channel polarization , originally proposed for binary - input channels , is generalized to arbitrary discrete memoryless channels .
specifically , it is shown that when the input alphabet size is a prime number , a similar construction to that for the binary case leads to polarization .
this method can be extended to channels of composite input alphabet sizes by decomposing such channels into a set of channels with prime input alphabet sizes .
it is also shown that all discrete memoryless channels can be polarized by randomized constructions .
the introduction of randomness does not change the order of complexity of polar code construction , encoding , and decoding .
a previous result on the error probability behavior of polar codes is also extended to the case of arbitrary discrete memoryless channels .
the generalization of polarization to channels with arbitrary finite input alphabet sizes leads to polar - coding methods for approaching the true ( as opposed to symmetric ) channel capacity of arbitrary channels with discrete or continuous input alphabets .
capacity - achieving codes , channel polarization , polar codes . .
And you have already written the first three sentences of the full article: channel polarization was introduced in @xcite for binary input discrete memoryless channels as a coding technique to construct codes called polar codes for data transmission .
polar codes are capable of achieving the ` symmetric capacity ' of any binary input channel , using low - complexity encoding and decoding algorithms . in terms of the block - length @xmath0
, polar codes can be encoded and decoded in complexity @xmath1 and achieve a block error probability that decays roughly like @xmath2 ..
Please generate the next two sentences of the article | the latter result was shown in @xcite .
the aim of this note is to extend these results of @xcite to dmcs with @xmath3-ary inputs for any finite integer @xmath4 . to that end , we recall the polarization construction and outline how the results above were shown . |
5,478 | Suppose that you have an abstract for a scientific paper: we report on the formation and evolution of two large - scale , synchrotron - emitting jets from the black hole candidate h following its reactivation in 2003 . in november 2003
after the end of its 2003 outburst , we noticed , in observations with the australia telescope compact array , the presence of a new and variable radio source about 4.6 to the east of h , that was later found to move away from h. in february 2004 , we detected a radio source to the west of h , symmetrically placed relative to the eastern jet . in 2004 , follow - up x - ray observations with _
chandra _ led to the discovery of x - ray emission associated with the two radio sources .
this likely indicates that we are witnessing the interaction of relativistic jets from h with the interstellar medium causing in - situ particle acceleration .
the spectral energy distribution of the jets during the decay phase is consistent with a classical synchrotron spectrum of a single electron distribution from radio up to x - rays , implying the production of very high energy ( @xmath0 10 tev ) particles in those jets .
we discuss the jet kinematics , highlighting the presence of a significantly relativistic flow in h almost a year after the ejection event . .
And you have already written the first three sentences of the full article: relativistic jets are now believed to be a common occurrence in black hole x - ray binaries ( e.g. corbel 2004 , fender 2004 ) .
the optically thin synchrotron spectra of the discrete ejection events ( the so - called superluminal jets ) imply that the emission becomes much fainter at higher frequencies . for that reason , such events
were only observed at radio frequencies ..
Please generate the next two sentences of the article | however , sams et al .
( 1996 ) reported the detection of extended infrared emission in after a massive ejection event that could be of synchrotron nature . |
5,479 | Suppose that you have an abstract for a scientific paper: theoretical research on extragalactic masers ( and hence this review ) is almost entirely directed toward 22 ghz water masers in circumnuclear disks with the focus being the near ideal masing disk at the nucleus of the galaxy ngc4258 .
the discussion here is organized around ( 1 ) the excitation and conditions for the masers , ( 2 ) the spatial and spectral appearance of the maser emission , and ( 3 ) the mass accretion rate and structure of the disk . in addition , a summary is given of the basic physics ( spectral linebeadths and maser polarization ) that underlies certain interpretations of these and other astrophysical masers . # 1#2 .
And you have already written the first three sentences of the full article: although there are some thirty galaxies in which h@xmath0o masers are observed ( certain others have oh masers ) , there is little in the way of theory " other than for the few where there is evidence for disk structure . even for these , almost all of the theoretical activity has been directed toward ngc4258 where the highly refined observations of 22 ghz water masers in a near ideal , thin keplerian disk provide the best opportunity for applying and testing ideas .
my discussion of the theory and extraglactic masers " is thus largely a summary of theory directed toward the masers in a single galaxy but it is a paradigm of considerable importance , and the ideas involve the basic description of molecular accretion disks near active galactic nuclei .
analysis of the structure of this disk utilizing information from maser observations potentially provides opportunities to assess the mass accretion rate which , when related to the energy emitted from this nucleus in other wavebands ( x - ray , infrared ) , bears on current issues concerning active galactic nuclei especially , on the possibility for advection dominated accretion flows . such analysis also may help clarify the nature of the long sought mechanism for viscosity in accretion disks ..
Please generate the next two sentences of the article | further , the masing disk in ngc4258 provides arguably the best evidence for massive black hole at the nucleus of an active ( or at least mildly active ) galaxy .
see moran , greenhill , & herrnstein ( 1999 ) for a summary of the observational data about extragalactic h@xmath0o masers . |
5,480 | Suppose that you have an abstract for a scientific paper: we investigate an explicite formula for ground state energy of the anisotropic xy chain in transverse magnetic field .
in particular , we examine the smoothness properties of this expression .
we explicitly demonstrate that the ground - state energy is infinitely differentiable on the boundary between ferromagnetic and oscillatory phases .
we also confirm known 2d - ising type behaviour in the neighbourhood of certain lines of phase diagram and give more detailed information there , calculating a few next - to - leading exponents as well as the corresponding amplitudes . .
And you have already written the first three sentences of the full article: the quantum xy spin chain and its extensions have been studied for a very long time and from many different perspectives .
it is due to a couple of reasons .
first of all , it is possible to obtain an exact solution ( for spin one - half case ) in the language of non - interacting fermions @xcite ..
Please generate the next two sentences of the article | it is interesting for its own , and moreover it can be used in testing various techniques that are applied to a wide range of non - integrable systems @xcite .
another motivation is to use the model to describe the experimental data of quasi - one - dimensional systems @xcite . and |
5,481 | Suppose that you have an abstract for a scientific paper: the uv upturn phenomenon observed in elliptical galaxies is attractive for its potential value as an age indicator of old stellar systems .
we present our most recent population models for the uv evolution of elliptical galaxies .
we confirm that the dominant uv sources are either metal - poor or metal - rich hot horizontal - branch ( hb ) stars in local giant ellipticals , but we also note that the contribution from post - asymptotic - giant - branch ( pagb ) stars overwhelms the uv spectrum at higher redshifts ( look - back times ) .
the model uv spectral energy distribution ( sed ) is therefore strongly affected by the current uncertainty of the mean mass of pagb stars at higher redshifts .
fortunately , our models suggest that the far - uv observations at @xmath0 could produce strong constraint on the pagb mass , while observations at lower redshifts ( @xmath1 ) would still provide constraints on the models on the origin of the uv upturn .
future observations of ellipticals from the _ stis / hst _ and planned _ galex _ space uv facility will provide crucial database required for more concrete calibration of our uv dating techniques for old stellar systems . .
And you have already written the first three sentences of the full article: recent observations on the origin of the uv upturn phenomenon of elliptical galaxies showed that hot hb and post - hb stars are the dominant uv sources in these systems ( ferguson et al .
1991 ; oconnell et al . 1992 ; king et al . 1992 ; bertola et al . 1995 ; brown et al 1997 ) . as demonstrated in our recent investigation ( yi et al .
1999 ) , it is still not clear , however , whether the dominant uv sources are metal poor ( metal - poor hb model " ; lee 1994 ; park & lee 1997 ) or metal rich ( metal - rich hb model " ; bressan et al ..
Please generate the next two sentences of the article | 1994 ; dorman et al 1995 ; yi et al 1998 ) .
the metal - poor hb model " suggests that the dominant uv sources are very old , hot metal - poor hb stars and their post - hb progeny , although metal - rich pagb stars also contribute some uv flux . in this picture , |
5,482 | Suppose that you have an abstract for a scientific paper: we report the discovery of a bright ( j = [email protected] ) methane brown dwarf , or t dwarf , by the two micron all sky survey .
this object , 2massi j0559191 - 140448 , is the first brown dwarf identified by the newly commissioned cormass instrument mounted on the palomar 60-inch telescope .
near - infrared spectra from 0.9 - 2.35 @xmath1 show characteristic ch@xmath2 bands at 1.1 , 1.3 , 1.6 , and 2.2 @xmath1 , which are significantly shallower than those seen in other t dwarfs discovered to date . coupled with the detection of an feh band at 0.9896 and two sets of k i doublets at j - band
, we propose that 2mass j0559 - 14 is a warm t dwarf , close to the transition between l and t spectral classes .
the brightness of this object makes it a good candidate for detailed investigation over a broad wavelength regime and at higher resolution . .
And you have already written the first three sentences of the full article: t dwarfs are brown dwarfs that exhibit methane absorption bands at 1.6 and 2.2 @xmath1 @xcite , and thus have effective temperatures t@xmath3 @xmath4 1200 - 1300 k @xcite .
the prototype for this class , gl 229b @xcite , was identified as a cool companion to the nearby m1v star gl 229a .
recently , seven field objects @xcite and another companion object @xcite have also been identified as t dwarfs ..
Please generate the next two sentences of the article | the rapid discovery of these cool brown dwarfs has been driven by new sky surveys , such as the two micron all sky survey ( * ? ? ? * hereafter 2mass ) and the sloan digital sky survey @xcite ; and deep near - infrared surveys , such as the eso new technology telescope deep field @xcite .
the t dwarfs identified to date are remarkably similar to gl 229b , with colors in the range @xmath50.2 @xmath4 j - k@xmath6 @xmath4 0.2 . |
5,483 | Suppose that you have an abstract for a scientific paper: in this study , one of the mean - field theories in nematics , the maier - saupe theory ( mst ) , is generalized within tsallis thermostatistics ( tt ) .
the variation of the order parameter versus temperature has been investigated and compared with experimental data for paa ( p - azoxyanisole ) . so far we believe that this is the first attempt of the application of tt in liquid crystals .
it is well known that mst fails to explain the experimental data for some of the nematics , one of which is paa .
however generalized mst ( gmst ) is able to account for the experimental data for a long range of temperatures .
also in this study , the effect of nonextensivity is shown for various values of the entropic index . _
pacs number(s ) : 05.20.-y , 05.70.-a , 61.30.-v , 61.30.cz , 61.30.gd_ .
And you have already written the first three sentences of the full article: there is a growing interest in the nonextensive generalization of the conventional boltzmann -gibbs statistical mechanics .
tsallis thermostatistics ( tt ) is one of these generalization attempts [ 1 ] and in this study , we generalize the maier - saupe theory ( mst ) [ 2 ] , a mean field theory especially used in nematic liquid crystals , and the variation of the order parameter of paa ( p - azoxyanisole , a nematic liquid crystals ) versus temperature is investigated within tt formalism .
mst fails to explain the experimental data for some of the nematics and paa is one of these nematics ..
Please generate the next two sentences of the article | it is well known that boltzmann - gibbs statistics ( bg ) seems to fail for the systems , ( i ) with long range microscopic interactions , ( ii ) with long range memory effects and ( iii ) which evolves in a multifractal space - time .
therefore there is a tendency for nonextensive formalisms . |
5,484 | Suppose that you have an abstract for a scientific paper: we construct an explicit model to describe fermions confined on a four dimensional brane embedded in a five dimensional anti - de sitter spacetime .
we extend previous works to accommodate massive bound states on the brane and exhibit the transverse structure of the fermionic fields .
we estimate analytically and calculate numerically the fermion mass spectrum on the brane , which we show to be discrete .
the confinement life - time of the bound states is evaluated , and it is shown that existing constraints can be made compatible with the existence of massive fermions trapped on the brane for durations much longer than the age of the universe
. 0.25 cm .
And you have already written the first three sentences of the full article: the idea that our universe may be a hypermembrane in a five dimensional spacetime has received some attention in the last few years after it was realized that gravity could be localized on a three - brane embedded in an anti - de sitter spacetime @xcite . since then
, much work has been done in a cosmological context @xcite and there is hope that a consistent ( i.e. , mathematically self - contained and observationally satisfying ) high dimensional model might soon be formulated .
for instance , it has been proposed that a model @xcite based on such ideas could present itself as an alternative to the inflationary paradigm , although for the time being the controversy as to whether or not such a model might have anything in common with our universe is still going on @xcite ..
Please generate the next two sentences of the article | the idea is not new however , but has evolved from the standard kaluza - klein approach to that of particle localization on a higher dimensional defect @xcite . in particular , it has been shown that massless bulk scalars and gravitons share the property to have a zero mode localized on the brane @xcite in the randall - sundrum model .
various mechanisms @xcite have been invoked according to which it would be possible to confine massless gauge bosons on a brane , so that there is hope to achieve a reasonable model including all the known interactions in a purely four dimensional effective model . |
5,485 | Suppose that you have an abstract for a scientific paper: many correlated materials display a quantum critical point between a paramagnetic and a spin - density wave ( sdw ) state .
the sdw wave vector connects points , so - called hot spots , on opposite sides of the fermi surface .
the fermi velocities at these pairs of points are in general not parallel . here
we consider the case where pairs of hot spots coalesce , and the wave vector @xmath0 of the sdw connects hot spots with parallel fermi velocities . using the specific example of electron - doped cuprates , we first show that kanamori screening and generic features of the lindhard function make this case experimentally relevant .
the temperature dependence of the correlation length , the spin susceptibility and the self - energy at the hot spots are found using the two - particle - self - consistent theory and specific numerical examples worked out for band and interaction parameters characteristic of the electron - doped cuprates .
while the curvature of the fermi surface at the hot spots leads to deviations from perfect nesting , the pseudo - nesting conditions lead to drastic modifications of the temperature dependence of these physical observables : neglecting logarithmic corrections , the correlation length @xmath1 scales like @xmath2 , namely @xmath3 instead of the naive @xmath4 , the @xmath0 static spin susceptibility @xmath5 like @xmath6 , and the imaginary part of the self - energy at the hot spots like @xmath7 . the correction @xmath8 to the korringa nmr relaxation rate is subdominant .
we also consider this problem at zero temperature , or for frequencies larger than temperature , using a field - theoretical model of gapless collective bosonic modes ( sdw fluctuations ) interacting with fermions .
the imaginary part of the retarded fermionic self - energy close to the hot spots scales as @xmath9 .
this is less singular than earlier predictions of the form @xmath10 .
the difference arises from the effects of umklapp terms that were not included in previous studies . .
And you have already written the first three sentences of the full article: quantum phase transitions between a fermi liquid and magnetic phases have been a subject of experimental and theoretical investigations for several decades @xcite .
the transition to a spin - density - wave ( sdw ) in particular is relevant to problems of current interest . in the cuprates ,
daou _ et al . _.
Please generate the next two sentences of the article | @xcite argued that the fermi surface change associated with this transition is a key to understanding anomalous normal state properties .
recent studies in the pnictides @xcite , heavy fermion materials @xcite and organic superconductors @xcite focus on the relation between the sdw and superconductivity . |
5,486 | Suppose that you have an abstract for a scientific paper: this article is devoted to the computation of jack connection coefficients , a generalization of the connection coefficients of two classical commutative subalgebras of the group algebra of the symmetric group : the class algebra and the double coset algebra .
the connection coefficients of these two algebraic structures are of significant interest in the study of schur and zonal polynomials as well as the irreducible characters of the symmetric group and the zonal spherical functions .
furthermore they play an important role in combinatorics as they give the number of factorizations of a permutation into a product of permutations with given cyclic properties and , in some cases , the number of hypermaps embedded in orientable and locally orientable surfaces with specified vertex degree distribution .
+ usually studied separately , these two families of coefficients share strong similar properties . first ( partially ) introduced by goulden and jackson in 1996 , jack connection coefficients provide a natural unified approach closely related to the theory of jack polynomials , a family of bases in the ring of symmetric functions indexed by a parameter @xmath0 that generalizes both schur ( case @xmath1 ) and zonal polynomials ( case @xmath2 ) .
jack connection coefficients are also directly linked to jack characters , a general view of the characters of the symmetric group and the zonal spherical functions .
goulden and jackson conjectured that these coefficients are polynomials in @xmath0 with nice combinatorial properties , the so - called _ matchings - jack conjecture_. + in this paper , we use the theory of jack symmetric functions and the laplace beltrami operator to show the polynomial properties of jack connection coefficients in some important cases .
we also provide explicit formulations including notably a generalization of a classical formula of denes for the number of minimal factorizations of a permutation into transpositions . .
And you have already written the first three sentences of the full article: for any integer @xmath3 we note @xmath4 the symmetric group on @xmath3 elements and @xmath5 an integer partition of @xmath6 with @xmath7 parts sorted in decreasing order .
if @xmath8 is the number of parts of @xmath9 that are equal to @xmath10 , then we may write @xmath9 as @xmath11 $ ] and define @xmath12 and @xmath13 .
a partition @xmath14 is usually represented as a young diagram of @xmath15 boxes arranged in @xmath16 lines so that the @xmath10-th line contains @xmath17 boxes . given a box @xmath18 in the diagram of @xmath14 , let @xmath19 be the number of boxes to the north , south , east , west of @xmath18 respectively ..
Please generate the next two sentences of the article | these statistics are called * co - leglength , leglength , armlength , co - armlength * respectively .
we note for some parameter @xmath0 : @xmath20 moreover , @xmath21 is the conjugate of partition @xmath9 , for two integer partitions @xmath9 and @xmath22 , we denote @xmath23 if for all @xmath24 , @xmath25 and we denote @xmath26 the quantity @xmath27 let @xmath28 be the ring of symmetric functions |
5,487 | Suppose that you have an abstract for a scientific paper: we report on the excitation energy dependence of the inner ring in the exciton emission pattern .
the contrast of the inner ring is found to decrease with lowering excitation energy .
excitation by light tuned to the direct exciton resonance is found to effectively suppress excitation - induced heating of indirect excitons and facilitate the realization of a cold and dense exciton gas .
the excitation energy dependence of the inner ring is explained in terms of exciton transport and cooling . .
And you have already written the first three sentences of the full article: an indirect exciton in a coupled quantum well structure ( cqw ) is a bound pair of an electron and a hole confined to spatially separated qws .
the small overlap of the electron and the hole wavefunctions increases the lifetime of indirect excitons by orders of magnitude compared to the lifetime of regular direct excitons .
in addition , indirect excitons are oriented dipoles with a built - in dipole moment @xmath0 , where @xmath1 is close to the separation between the qw centers ..
Please generate the next two sentences of the article | the repulsive dipole - dipole interaction between indirect excitons allows them to screen in - plane disorder in the structure @xcite . as a result
, indirect excitons can travel over large distances before optically decaying @xcite . |
5,488 | Suppose that you have an abstract for a scientific paper: we explore the many body physics of a bose condensed atom gas at finite temperature through the raman transition between two hyperfine levels . unlike the bragg scattering where the phonon - like nature of the collective excitations has been observed ,
a different branch of thermal atom excitation is found theoretically in the raman scattering .
this excitation is predicted in the generalized random phase approximation ( grpa ) and has a gapped and parabolic dispersion relation .
the gap energy results from the exchange interaction and is released during the raman transition .
the scattering rate is determined versus the transition frequency @xmath0 and the transferred momentum @xmath1 and shows the corresponding resonance around this gap .
nevertheless , the raman scattering process is attenuated by the superfluid part of the gas .
the macroscopic wave function of the condensate deforms its shape in order to screen locally the external potential displayed by the raman light beams
. this screening is total for a condensed atom transition in order to prevent the condensate from incoherent scattering .
the experimental observation of this result would explain some of the reasons why a superfluid condensate moves coherently without any friction with its surrounding . .
And you have already written the first three sentences of the full article: among the various approximations existing in the literature to describe a diluted bose condensed gas at finite temperature , the generalized random phase approximation ( grpa ) has been the subject of several studies @xcite .
this approximation has attracted a special attention since it is the only one in the literature with two important properties : 1 ) in agreement with the hugenholtz - pines theorem @xcite , it predicts the observed gapless and phonon - like excitations ; 2 ) the mass , momentum and energy conservation laws are fulfilled in the gas dynamical description . an approximation that satisfies these properties is said to be _ gapless _ and _ conserving _ @xcite .
besides these unique features , the grpa predicts also other phenomena , namely a second branch of excitations and the dynamical screening of the interaction potential ..
Please generate the next two sentences of the article | these phenomena appear also in the case of a gas of charged particles or plasma .
the possibility of a second kind of excitation has been explained quite extensively in @xcite . |
5,489 | Suppose that you have an abstract for a scientific paper: in this paper , we study the coxeter transformations of the derived categories of coherent sheaves on smooth complete varieties .
we first obtain that if the rank of the grothendieck group is finite , say @xmath0 , then its characteristic polynomials is @xmath1 , where @xmath2 is dimension of the variety .
we then study the jordan canonical forms of the coxeter transformations for rational surfaces , smooth complete toric varieties with ample canonical or anticanonical bundles , and prove that their jordan canonical forms can determine and be determined by the betti numbers of these varieties . as an application , we compute the jordan canonical forms of tensor products of matrices .
xy [ section ] [ theorem]acknowledgement [ theorem]algorithm [ theorem]axiom [ theorem]case [ theorem]claim [ theorem]conclusion [ theorem]condition [ theorem]conjecture [ theorem]construction [ theorem]corollary [ theorem]criterion [ theorem]definition [ theorem]example [ theorem]exercise [ theorem]lemma [ theorem]notation [ theorem]problem [ theorem]proposition [ theorem]remark [ theorem]solution [ theorem]summary p corresponding author ] .
And you have already written the first three sentences of the full article: coxeter transformations play an important role in the development of lie group and lie algebra theory . for a compact lie group , a coxeter transformation or a coxeter element is defined to be the product of all the reflections in the root system initially . h. s. coxeter studies these elements and their eigenvalues in @xcite .
he also observes that the number of roots in the corresponding root system is equal to the product of the order of the coxeter transformation ( called the coxeter number ) and the number of eigenvalues of the coxeter transformation , which is proved by a. j. coleman in @xcite .
+ in @xcite , v. f. subbotin and r. b. stekolshchik consider the eigenvalues and the jordan canonical forms of the coxeter transformations for symmetrizable cartan matrices ..
Please generate the next two sentences of the article | they prove that the jordan canonical form of the coxeter transformation is diagonal if and only if the tits form is non - degenerate .
for an extended dynkin diagram , the jordan canonical form of the coxeter transformation contains only one @xmath3 jordan block and all eigenvalues have norm @xmath4 . |
5,490 | Suppose that you have an abstract for a scientific paper: we draw attention to the close relationship between the anisotropy parameter @xmath0 for stellar orbits in elliptical galaxies and the temperature @xmath1 of the hot interstellar gas . for nearly spherical galaxies
, the gas density @xmath2 can be accurately determined from x - ray observations and the stellar luminosity density @xmath3 can be accurately found from the optical surface brightness .
the jeans equation and hydrostatic equilibrium establish a connection between @xmath0 and @xmath1 that must be consistent with the observed stellar velocity dispersion .
optical observations of the bright elliptical galaxy ngc 4472 indicate @xmath4 within the effective radius .
however , the x - ray gas temperature profile @xmath1 for ngc 4472 requires significantly larger anisotropy , @xmath5 , about twice as large as the optical value .
this strong preference for radial stellar orbits must be understood in terms of the formation history of massive elliptical galaxies .
conversely , if the smaller , optically determined @xmath0 is indeed correct , we are led to the important conclusion that the temperature profile @xmath1 of the hot interstellar gas in ngc 4472 must differ from that indicated by x - ray observations , or that the hot gas is not in hydrostatic equilibrium .
.2 in .
And you have already written the first three sentences of the full article: the anisotropy of stellar orbits in elliptical galaxies can be estimated from the temperature of the hot interstellar gas through which they move .
these two quite different galactic attributes are intimately related by the jeans equation for the stars and the condition for hydrostatic equilibrium in the gas .
this simple relationship is valuable since both the anisotropy and gas temperature are difficult to extract from optical and x - ray observations , respectively ..
Please generate the next two sentences of the article | many massive elliptical galaxies are nearly spherical ( merritt & trembly 1996 ) and slowly rotating , but their stellar velocity ellipsoids are not in general isotropic .
the non - spherical nature of the stellar velocity dispersion is represented by the parameter @xmath6 where @xmath7 is the radial stellar velocity dispersion and @xmath8 is the dispersion in a transverse direction , i.e. @xmath9 . if the orbits are predominantly radial , @xmath10 , the line of sight velocity profile becomes more strongly peaked than a gaussian profile with increasing projected radius @xmath11 ; if the orbits are mostly tangential , @xmath12 , the profile is more flat - topped and becomes broader with increasing radius . |
5,491 | Suppose that you have an abstract for a scientific paper: _ we show , using quantum field theory , that performing a large number of identical repetitions of the same measurement does not only preserve the initial state of the wave function ( the zeno effect ) , but also produces additional physical effects .
we first demonstrate that a zeno type effect can emerges also in the framework of quantum field theory , that is , as a quantum field phenomenon .
we also derive a zeno type effect from quantum field theory for the general case in which the initial and final states are different .
the basic physical entities dealt with in this work are not the conventional once - perfomed physical processes , but their @xmath0 times repetition where @xmath0 tends to infinity .
we show that the presence of these repetitions entails the presence of additional excited state energies , and the absence of them entails the absence of these excited energies . _ .
And you have already written the first three sentences of the full article: the problem of obtaining additional physical effects only due to multiple repetitions of the same measurement or interaction has been discussed both analytically @xcite and experimentally @xcite .
these phenomena , in which one may preserves in time an initially prepared state or even `` guide '' its time evolution to another final predetermined state @xcite in contrast to the known rules of quantum mechanics by which the result of measurement can not be known beforehand , are collectively termed quantum zeno effect @xcite .
they were discussed exclusively at the level of either the schroedinger equation @xcite , or by using the density matrix @xcite ..
Please generate the next two sentences of the article | we show in this work , using specific examples , that these phenomena may be found also in the context of quantum field theory .
moreover , it has been shown @xcite , using the spin example , that these repetitions not only preserves or guide to some predetermined state but also may result in entirely new effects as will be explained . |
5,492 | Suppose that you have an abstract for a scientific paper: the power spectrum of local field potentials ( lfps ) has been reported to scale as the inverse of the frequency , but the origin of this `` @xmath0 noise '' is at present unclear .
macroscopic measurements in cortical tissue demonstrated that electric conductivity ( as well as permittivity ) is frequency dependent , while other measurements failed to evidence any dependence on frequency . in the present paper , we propose a model of the genesis of lfps which accounts for the above data and contradictions .
starting from first principles ( maxwell equations ) , we introduce a macroscopic formalism in which macroscopic measurements are naturally incorporated , and also examine different physical causes for the frequency dependence .
we suggest that ionic diffusion primes over electric field effects , and is responsible for the frequency dependence .
this explains the contradictory observations , and also reproduces the @xmath0 power spectral structure of lfps , as well as more complex frequency scaling
. finally , we suggest a measurement method to reveal the frequency dependence of current propagation in biological tissue , and which could be used to directly test the predictions of the present formalism . .
And you have already written the first three sentences of the full article: macroscopic measurements of brain activity , such as the electroencephalogram ( eeg ) , magnetoencephalogram or local field potentials ( lfp ) , display approximately @xmath0 frequency scaling in their power spectra @xcite .
the origin of such @xmath0 `` noise '' is at present unclear .
@xmath0 spectra can result from self - organized critical phenomena @xcite , suggesting that neuronal activity may be working according to such states @xcite ..
Please generate the next two sentences of the article | alternatively , the @xmath0 scaling may be due to filtering properties of the currents through extracellular media @xcite .
the latter hypothesis , however , was resting on indirect evidence , and still needs to be examined theoretically , which is one of the motivations of the present paper . a _ continuum model _ @xcite of lfps incorporated the inhomogeneities of the extracellular medium into continuous spatial variations of conductivity ( @xmath1 ) and permittivity ( @xmath2 ) parameters . |
5,493 | Suppose that you have an abstract for a scientific paper: the metastable vapor - liquid coexistence of short - range attractive fluids hinders the formation of crystal nuclei , which in turn makes difficult the progress of the system towards its vapor - solid ground state . in this letter
we show that crystal growth can be assisted by imposing temperature fluctuations . by
so doing the obtained solid is nearly a fcc monocrystal in contrast with the extreme polycrystalline structure obtained at low temperatures .
the study is carried out by combining the replica exchange monte carlo method and the standard slab technique .
the obtained results suggest a pathway for growing coherent crystals from the metastable liquid .
this is particularly relevant for the crystallization of globular proteins . .
And you have already written the first three sentences of the full article: the temperature - density phase diagram drastically changes with the range of the attractive part of the interparticle potential @xcite .
so that , when it is less than half of the particle s radius , the critical point locates below the freezing curve and the corresponding vapor - liquid phases are metastable @xcite .
this inhibits crystal formation . to overcome this obstacle ,.
Please generate the next two sentences of the article | it was proposed to take advantage of natural fluctuations occurring in the vicinity of the critical point , which may produce the first stable seed to grow the crystal phase @xcite .
this pathway for crystallization was unsuccessfully applied to globular proteins solutions , which are known to follow the phase behavior described by short - range attractive model fluids @xcite . alternatively , temporal variations of protein concentration enhance crystallization , pointing out that fluctuations , though externally imposed , indeed promote nucleation and the crystal growth @xcite . |
5,494 | Suppose that you have an abstract for a scientific paper: we consider the behavior of a collective variable in a complex system formed by a finite number of interacting subunits .
each of them is characterized by a degree of freedom with an intrinsic nonlinear bistable stochastic dynamics .
the lack of ergodicity of the collective variable requires the consideration of a feedback mechanism of the collective behavior on the individual dynamics .
we explore numerically this issue within the context of two simple finite models with a feedback mechanism of the weiss mean - field type : a global coupling model and another one with nearest neighbors coupling . .
And you have already written the first three sentences of the full article: complex hierarchical systems admit several levels of description . at a microscopic level ,
the interest lies on the dynamical behavior of the constituent elements .
thus , at this level of description , one needs to follow the time evolution of very many microscopic variables . on the other hand , at the macroscopic level.
Please generate the next two sentences of the article | , one describes the system in terms of just a few collective variables characterizing it as a whole .
the laws describing the behavior of collective variables could , in principle , be deduced from the dynamical laws governing the elementary constituents . in practice |
5,495 | Suppose that you have an abstract for a scientific paper: we analyze the way topological constraints and inhomogeneity in the excitability influence the dynamics of spiral waves on spheres and punctured spheres of excitable media .
we generalize the definition of an index such that it characterizes not only each spiral but also each hole in punctured , oriented , compact , two - dimensional differentiable manifolds and show that the sum of the indices is conserved and zero . we also show that heterogeneity and geometry are responsible for the formation of various spiral wave attractors , in particular , pairs of spirals in which one spiral acts as a source and a second as a sink the latter similar to an antispiral .
the results provide a basis for the analysis of the propagation of waves in heterogeneous excitable media in physical and biological systems . .
And you have already written the first three sentences of the full article: geometry and inhomogeneity influence pattern formation in chemical and biological systems .
@xcite one example where these two factors play a crucial role is in the experimental observations of distinctive spiral wave dynamics on the surfaces of spherical beads , which are excitable inhomogeneous chemical media @xcite .
a biological example is the origin of abnormal cardiac rhythms in the human heart which depend on the anatomical substrate ..
Please generate the next two sentences of the article | the heart possesses a complex nonplanar geometry with multiple chambers , with holes corresponding to valves and blood vessels .
some serious arrhythmias are associated with circulating spiral waves similar to those observed in chemical media @xcite . since |
5,496 | Suppose that you have an abstract for a scientific paper: a @xmath0-dimensional framework is an embedding of the vertices and edges of a graph in @xmath1 .
a @xmath0-dimensional framework is globally rigid if every other @xmath0-dimensional framework with the same edge lengths has the same pairwise distances between the vertices .
a graph is generically globally rigid in dimension @xmath0 ( @xmath0-ggr ) if every generic framework is globally rigid .
the @xmath0-dimensional framework of a @xmath0-ggr graph is universally rigid if for @xmath2 every @xmath3-dimensional framework with the same edge lengths has the same pairwise distances between the vertices .
we establish a strong connection between global and universal rigidity by showing that all 1 and 2-ggr graphs and an infinite number of higher dimensional @xmath0-ggr graphs have a generic universally rigid framework .
= 1 .
And you have already written the first three sentences of the full article: an interesting and difficult problem in graph theory is the graph embedding problem .
the problem is as follows : given a collection of vertices in @xmath1 and the pairwise distances between some of them , find the positions of the vertices up to some arbitrary rigid motion .
the problem has shown to be np - hard @xcite ; however , solutions may be found using semidefinite programming @xcite ..
Please generate the next two sentences of the article | unfortunately the embeddings given by semidefinite programming may be in some larger dimensional space rather than @xmath0-dimensional .
however , if the framework is _ universally rigid _ then solutions are automatically constrained to be @xmath0-dimensional . this paper seeks to address the question raised by gortler and thurston : `` for a graph @xmath4 which is @xmath0-ggr is there always a generic framework in the space of @xmath0-dimensional frameworks , @xmath5 that is universally rigid?''@xcite . |
5,497 | Suppose that you have an abstract for a scientific paper: inertial sensors relying on atom interferometry offer a breakthrough advance in a variety of applications , such as inertial navigation , gravimetry or ground and space based tests of fundamental physics .
these instruments require a quiet environment to reach their performance and using them outside the laboratory remains a challenge . here , we report the first operation of an airborne matter wave accelerometer set up aboard a 0-g plane and operating during the standard gravity ( 1-g ) and microgravity ( 0-g ) phases of the flight . at 1-g ,
the sensor can detect inertial effects more than 300 times weaker than the typical acceleration fluctuations of the aircraft .
we describe the improvement of the interferometer sensitivity in 0-g , which reaches @xmath0 with our current setup .
we finally discuss the extension of our method to airborne and spaceborne tests of the universality of free fall with matter waves .
matter wave inertial sensing relies on the capability of controling the wave nature of matter to build an interferometer and accurately measure a phase difference @xcite . since the particle associated to the matter wave senses inertial or gravitational effects , the interferometer represents an accurate inertial probe .
in particular , atom interferometers ( ais ) have benefited from the outstanding developments of laser - cooling techniques and reached accuracies comparable to those of inertial sensors based on optical interferometry .
thanks to their long term stability , ais offer a breakthrough advance in accelerometry , gyroscopy and gravimetry , for applications to inertial guidance @xcite , geoid determinations @xcite , geophysics @xcite and metrology @xcite .
in addition , ais are excellent candidates for laboratory - based tests of general relativity ( gr ) that could compete with the current tests which consider astronomical or macroscopic bodies @xcite .
for example , ais may provide new answers to the question of whether the free fall acceleration of a particle....
And you have already written the first three sentences of the full article: our experiment relies on the coherent manipulation of atomic quantum states using light pulses @xcite .
we use telecom based laser sources that provide high frequency stability and power in a compact and integrated setup @xcite . starting from a @xmath2 vapor , we load in @xmath5 a cloud of about @xmath6 atoms laser cooled down to 10 @xmath7k , and select the atoms in a magnetic field insensitive ( @xmath8 ) zeeman sublevel .
we then apply a velocity selective raman light pulse @xcite carrying two counterpropagating laser fields so as to keep @xmath9 atoms which enter the ai with a longitudinal velocity distribution corresponding to a temperature of 300 nk ..
Please generate the next two sentences of the article | the raman laser beams are aligned along the plane wings direction ( y axis , figure 1 ) and are retroreflected by a mirror attached to the aircraft structure and following its motion .
the ai consists of a sequence of three successive raman light pulses to split , redirect and recombine the atomic wavepackets ( see figure 1d ) . |
5,498 | Suppose that you have an abstract for a scientific paper: using a multiphase transport model , we study the relative importance of @xmath0 suppression mechanisms due to plasma screening , gluon scattering , and hadron absorption in heavy ion collisions at the relativistic heavy ion collider .
we find that for collisions between heavy nuclei such as au+au , both plasma screening and gluon scattering are important . as a result ,
the effect due to absorption by hadrons becomes relatively minor .
the final @xmath0 survival probability in these collisions is only a few percent . in the case of collisions between light nuclei such as s+s ,
the effect of plasma screening is , however , negligible in spite of the initial high parton density .
the final @xmath0 survival probability thus remains appreciable after comparable absorption effects due to gluons and hadrons . .
And you have already written the first three sentences of the full article: according to the fundamental theory of the strong interactions , quantum chromo - dynamics ( qcd ) , normal nuclear matter is expected to undergo a phase transition to deconfined quarks and gluons when its density and/or temperature are high @xcite .
to produce such a quark - gluon plasma ( qgp ) in the laboratory , experiments involving collisions of nuclei at relativistic energies have been carried out at the cern sps @xcite .
possible evidences for the production of this new phase of matter have recently been announced @xcite ..
Please generate the next two sentences of the article | further experiments at the relativistic heavy ion collider ( rhic ) , which allows collisions at much high energies than those available previously , are expected to provide a better opportunity to create the quark - gluon plasma and to study its properties . since
quarks and gluons can not be directly detected in experiments , many indirect observables have been proposed as possible signatures for the qgp . |
5,499 | Suppose that you have an abstract for a scientific paper: the mixing effectiveness , i.e. , the enhancement of molecular diffusion , of a flow can be quantified in terms of the suppression of concentration variance of a passive scalar sustained by steady sources and sinks . the mixing enhancement defined this way is the ratio of the rms fluctuations of the scalar mixed by molecular diffusion alone to the ( statistically steady - state ) rms fluctuations of the scalar density in the presence of stirring .
this measure of the effectiveness of the stirring is naturally related to the enhancement factor of the equivalent eddy diffusivity over molecular diffusion , and depends on the pclet number .
it was recently noted that the maximum possible mixing enhancement at a given pclet number depends as well on the structure of the sources and sinks .
that is , the mixing efficiency , the effective diffusivity , or the eddy diffusion of a flow generally depends on the sources and sinks of whatever is being stirred . here
we present the results of particle - based simulations quantitatively confirming the source - sink dependence of the mixing enhancement as a function of pclet number for a model flow . .
And you have already written the first three sentences of the full article: mixing by fluid flows is a ubiquitous natural phenomenon that plays a central role in many of the applied sciences and engineering .
a geophysical example is the mixing of aerosols ( e.g. , @xmath0 supplied by a volcano , say , or by human activity ) in the atmosphere .
aerosols are dispersed by molecular diffusion on the smallest scales but are more effectively spread globally by atmospheric flows ..
Please generate the next two sentences of the article | the density and density fluctuations of some aerosols influence the albedo of the earth and thus have a significant environmental impact .
hence it is important to understand fundamental properties of dispersion , mixing , and the reduction of concentration fluctuations by stirring flow fields . |
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