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4,400 | Suppose that you have an abstract for a scientific paper: using a data sample of integrated luminosity of about 33 pb@xmath0 collected around 3.773 gev with the besii detector at the bepc collider , the semileptonic decays @xmath1 , @xmath2 and the hadronic decay @xmath3 are studied .
the upper limits of the branching fractions are set to be @xmath4 2.01% and @xmath5 2.04% at the 90% confidence level .
the ratio of the branching fractions for @xmath3 relative to @xmath6 is measured to be @xmath7 .
in addition , the branching fraction for @xmath3 is obtained to be @xmath8 . .
And you have already written the first three sentences of the full article: searching for new modes in charm decays is of great interest .
it not only investigates possible decay mechanism and finds its contribution to the total decay width , but is also useful to simulate accurately cascade decays of bottom mesons and to eliminate backgrounds of charm modes in studying bottom decays . in this paper
, the semileptonic and hadronic @xmath9 decays in which the final state particles contain a @xmath10 meson are studied . whenever a specific state or decay mode is mentioned in this work.
Please generate the next two sentences of the article | , the charge - conjugate state or decay mode is always implied .
the besii detector upgraded from the bes @xcite is a large solid - angle magnetic spectrometer described in detail elsewhere @xcite . a 12-layer vertex chamber ( vc ) surrounding the beryllium beam pipe |
4,401 | Suppose that you have an abstract for a scientific paper: we propose a three terminal heat engine based on semiconductor superlattices for energy harvesting .
the periodicity of the superlattice structure creates an energy miniband , giving an energy window for allowed electron transport .
we find that this device delivers a large power , nearly twice than the heat engine based on quantum wells , with a small reduction of efficiency .
this engine also works as a refrigerator in a different regime of the system s parameters .
the thermoelectric performance of the refrigerator is analyzed , including the cooling power and coefficient of performance in the optimized condition .
we also calculate phonon heat current through the system , and explore the reduction of phonon heat current compared to the bulk material .
the direct phonon heat current is negligible at low temperatures , but dominates over the electronic at room temperature and we discuss ways to reduce it . .
And you have already written the first three sentences of the full article: there has been increasing interest in developing high efficiency , high power thermoelectric devices , constructed from the bottom - up using nanoscale designs .
the primary applications driving interest in this area are energy - harvesting , the collection and conversion of waste heat to electrical power , produced from sources ranging from hand - held electronics to industrial sources of heat , and refrigeration , actively cooling a spatial region via electrons to evacuate heat out of an area .
the use of nanoscale architecture instead of bulk materials is motivated by the low figure of merit - or poor thermoelectric conversion efficiency - of bulk materials , whereas conduction through nanoscale electronics can reach carnot efficiency ..
Please generate the next two sentences of the article | one way to produce high thermodynamic efficiency in the conversion of heat to power is the use of structures with sharp spectral features , such as quantum dots @xcite .
the use of quantum dots in thermoelectric transport has been extensively researched in the past several years @xcite . |
4,402 | Suppose that you have an abstract for a scientific paper: we report on the discovery of hat - p-12b , a transiting extrasolar planet orbiting the moderately bright @xmath0 k4 dwarf gsc 03033 - 00706 , with a period @xmath1d , transit epoch @xmath2 ( bjd ) and transit duration @xmath3d .
the host star has a mass of @xmath4@xmath5 , radius of @xmath6@xmath7 , effective temperature k and metallicity @xmath8 = { \ifthenelse{\equal{{i}}{i}}{{\ensuremath{-0.29\pm0.05}}}{{\ensuremath{-0.36\pm0.04}}}}$ ] .
we find a slight correlation between the observed spectral line bisector spans and the radial velocity , so we consider , and rule out , various blend configurations including a blend with a background eclipsing binary , and hierarchical triple systems where the eclipsing body is a star or a planet .
we conclude that a model consisting of a single star with a transiting planet best fits the observations , and show that a likely explanation for the apparent correlation is contamination from scattered moonlight . based on this model
, the planetary companion has a mass of @xmath9@xmath10 , and radius of @xmath11@xmath12 yielding a mean density of @xmath13@xmath14 . comparing these observations with recent theoretical models
we find that hat - p-12b is consistent with a @xmath15 gyr , mildly irradiated , h / he dominated planet with a core mass @xmath16 .
hat - p-12b is thus the least massive h / he dominated gas giant planet found to date .
this record was previously held by saturn . .
And you have already written the first three sentences of the full article: transiting extrasolar planets ( teps ) provide unique opportunities to study the physical properties of planetary mass objects outside of the solar system . by combining time - series photometric observations taken during transit with radial velocity ( rv ) measurements of the star ,
it is possible to precisely measure the mass and radius of the planet , if the stellar mass and radius can be determined by other means . the bulk density of the planet
may then be compared with the predictions of theoretical planetary structure models ( e.g. * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ; * ? ? ? |
4,403 | Suppose that you have an abstract for a scientific paper: it is shown that a highly phase sensitive polarization squeezed @xmath0-photon state can be generated by subtracting a diagonally polarized photon from the @xmath1 photon component generated in collinear type ii downconversion .
this polarization wedge state has the interesting property that its photon number distribution in the horizontal and vertical polarizations remains sharply defined for phase shifts of up to @xmath2 between the circularly polarized components .
phase shifts at the heisenberg limit are therefore observed as nearly deterministic transfers of a single photon between the horizontal and vertical polarization components . .
And you have already written the first three sentences of the full article: one of the most fundamental applications of non - classical light field states is the improvement of measurement precision beyond the standard quantum limits for classical light sources . of particular interest
is the possible enhancement of phase sensitivity in interferometry @xcite , which could be useful in a wide range of fields , from quantum lithography @xcite to atomic clocks @xcite .
it is well known that the optimal phase resolution @xmath3 that can be achieved using a non - classical @xmath4-photon state is given by the heisenberg limit of @xmath5 ..
Please generate the next two sentences of the article | recently , few photon interferometry at this limit has been accomplished by new methods of generating @xmath4-photon path entangled states using parametric downconversion and post - selection @xcite .
such path entangled states are an equal superposition of the two @xmath4-photon states where all photons are located in the same optical mode , @xmath6 . |
4,404 | Suppose that you have an abstract for a scientific paper: in many realistic networks , the edges representing the interactions between the nodes are time - varying .
there is growing evidence that the complex network that models the dynamics of the human brain has time - varying interconnections , i.e. , the network is evolving . based on this evidence ,
we construct a patient and data specific evolving network model ( comprising discrete - time dynamical systems ) in which epileptic seizures or their terminations in the brain are also determined by the nature of the time - varying interconnections between the nodes .
a novel and unique feature of our methodology is that the evolving network model remembers the data from which it was conceived from , in the sense that it evolves to almost regenerate the patient data even upon presenting an arbitrary initial condition to it .
we illustrate a potential utility of our methodology by constructing an evolving network from clinical data that aids in identifying an approximate seizure focus nodes in such a theoretically determined seizure focus are outgoing hubs that apparently act as spreaders of seizures .
we also point out the efficacy of removal of such spreaders in limiting seizures .
* keywords : mathematical modeling , time - varying network , state forgetting property , focal epilepsy , discrete - time dynamical system , nonautonomous dynamical system * .
And you have already written the first three sentences of the full article: increasingly , many complex systems are being modeled as networks since the framework of nodes representing the basic elements of the system and the interconnections of the network representing the interaction between the elements fits well for a theoretical study .
when the complex systems are large - dimensional dynamical systems , the network framework comprises many interacting subsystems of smaller dimension each of which constitutes a node . as a particular example , the whole or a portion of the entire neuronal activity in the human brain can be regarded as the consequential dynamics of interacting subsystems , where the dynamics of a subsystem is generated by a group of neurons .
the enormously interconnected subsystems in the brain generate a wide variety of dynamical patterns , synchronised activities and rhythms ..
Please generate the next two sentences of the article | epilepsy is a disorder that affects the nerve cell activity which in turn intermittently causes seizures . during such seizures
, patients could experience abnormal sensations including loss of consciousness . |
4,405 | Suppose that you have an abstract for a scientific paper: we derived chemical abundances for c , n , o , na , mg and al in 20 asymptotic giant branch ( agb ) stars in the globular cluster ngc 6752 . all these elements ( but mg )
show intrinsic star - to - star variations and statistically significant correlations or anticorrelations analogous to those commonly observed in red giant stars of globular clusters hosting multiple populations .
this demonstrates that , at odds with previous findings , both first and second generation stars populate the agb of ngc 6752 .
the comparison with the na abundances of red giant branch stars in the same cluster reveals that second generation stars ( with mild na and he enrichment ) do reach the agb phase .
the only objects that are not observed along the agb of ngc 6752 are stars with extreme na enhancement .
this is also consistent with standard stellar evolution models , showing that highly na and he enriched stars populate the bluest portion of the horizontal branch and , because of their low stellar masses , evolve directly to the white dwarf cooling sequence , skipping the agb phase . .
And you have already written the first three sentences of the full article: the vast majority of galactic globular clusters ( gcs ) host multiple stellar populations ( mps ) characterized by different abundance ratios of selected light elements ( see , e.g. , * ? ? ? * for a review ) : some stars share the same light element abundance ratios measured in galactic field stars with similar metallicity , but a large fraction of the cluster population has enhanced n , na , and al and depleted c and o abundances .
the patterns are not random , but anticorrelated variations of the pairs c - n and o - na are commonly observed .
these are generally considered to arise from hot hydrogen burning in a previous generation of more massive stars , as asymptotic giant branch ( agb ) stars @xcite , fast - rotating massive stars @xcite , interacting massive binary stars @xcite , and/or super - massive stars @xcite ..
Please generate the next two sentences of the article | objects with standard composition are commonly denoted as first generation ( fg ) stars , and those with modified chemistry as second generation ( sg ) stars , although the assumption that they are formed in subsequent star formation episodes is sometimes questioned ( see , e.g. , * ? ? ?
* ) . in a few gcs |
4,406 | Suppose that you have an abstract for a scientific paper: we present the first reconstruction of the three - dimensional shape of magnetic loops in an active region from two different vantage points based on simultaneously recorded images .
the images were taken by the two euvi telescopes of the secchi instrument onboard the recently launched stereo spacecraft when the heliocentric separation of the two space probes was 12 degrees .
we demostrate that these data allow to obtain a reliable three - dimensional reconstruction of sufficiently bright loops .
the result is compared with field lines derived from a coronal magnetic field model extrapolated from a photospheric magnetogram recorded nearly simultaneously by soho / mdi .
we attribute discrepancies between reconstructed loops and extrapolated field lines to the inadequacy of the linear force - free field model used for the extrapolation . .
And you have already written the first three sentences of the full article: with the launch of nasa s stereo mission in october 2006 , a new dimension of solar coronal observations has been opened . for the first time , objects above the solar surface can be perceived in three dimensions by analysing the stereo image pairs observed with the secchi instruments onboard the stereo spacecraft and without making a - priori assumptions about their shape .
the two stereo spacecraft orbit the sun at approximately 1 au near the ecliptic plane with a slowly increasing angle of about 45 degrees / year between stereo a and stereo b. each spacecraft is equipped with , among other instruments , an euv telescope ( secchi / euvi ) . for the objectives of the mission and
more details about the euvi telescopes see @xcite and @xcite ..
Please generate the next two sentences of the article | the major building blocks of the solar corona are loops of magnetic flux which are outlined by emissions at , e.g. , euv wavelengths . in principle , the magnetic field in the lower corona can be derived from surface magnetograms by way of extrapolations ( e.g. * ? ? ?
. however , missing boundary values and measurement errors may introduce considerable uncertainties in the extrapolation results so that there is an obvious need for an alternative three - dimensional determination of the coronal magnetic field geometry . among other goals of the mission , |
4,407 | Suppose that you have an abstract for a scientific paper: the lower critical field of the grains , @xmath0 , and the intragrain critical current density , @xmath1 , were determined for the superconducting ruthenate - cuprate rusr@xmath2gd@xmath3ce@xmath4cu@xmath2o@xmath5 [ ru-1222(gd ) ] through a systematic study of the hysteresis in magnetoresistance loops .
a reliable method , based on the effects of the magnetization of the grains on the net local field at the intergranular junctions is provided , circumventing the problem of the strong masking of the superconducting diamagnetic signal by the ferromagnetic background .
the temperature dependency of @xmath0 and @xmath1 both exhibit a smooth increase on cooling without saturation down to @xmath6 @xmath7 0.2 .
the obtained @xmath0 values vary between 150 and 1500 oe in the 0.2 @xmath8 @xmath9 @xmath8 0.4 interval , for samples annealed in an oxygen flow ; oxygenation under high pressure ( 50 atm ) leads to a further increase .
these values are much larger than the previously reported rough assessments ( 25 - 50 oe ) , using conventional magnetization measurements .
high @xmath1 values of @xmath10 10@xmath11 a/@xmath12 , comparable to the high - t@xmath13 cuprates , were obtained .
the @xmath14 and @xmath15 dependencies are explained in the context of a magnetic phase separation scenario . .
And you have already written the first three sentences of the full article: since the discovery of the so called magnetic superconductors rusr@xmath2rcu@xmath16o@xmath17 ( ru-1212 ) and rusr@xmath2(r , ce)@xmath2cu@xmath2o@xmath5 ( ru-1222 ) , with r = gd , eu,@xcite considerable effort has been devoted to the understanding of the interplay between the ferromagnetic ( fm ) component , emerging from the long - range order of the ru moments , and the onset of the superconducting ( sc ) state.@xcite among several important topics , the possibility of @xmath18-phase formation across the ruo@xmath2 layers,@xcite the itinerant or localized character of the magnetism of the ru moments , mccrone01,tallon02,mccrone02 the magnetic phase separation scenario of nanoscale fm clusters with superconductivity nucleating only in the surrounding antiferromagnetic matrix,@xcite and the possibility of triplet paring,@xcite have been considered to explain how this puzzling coexistence may occur . on the other hand ,
some important superconducting parameters have been less thoroughly investigated .
reports include the determination of the coherence length @xmath19 and the higher critical field @xmath20,@xcite and the intragrain london penetration length @xmath21,@xcite and rough estimations of the lower critical field of the grains , @xmath0.@xcite in relation to the determination of @xmath0 , a diamagnetic signal has been observed in a few cases at the low field range of the @xmath22 magnetization loops in ru-1222 , with a negative minimum at about 25 oeawana and 50 oe.@xcite there are also fewer studies on relevant intrinsic superconducting properties , such as the intragrain critical current density , @xmath1,felner ijmp mainly because the strong fm contribution to the magnetization from the ru sublattice makes impracticable the use of the magnetic hysteresis loops to determine both @xmath0 and @xmath1 . in the present study.
Please generate the next two sentences of the article | we overcome this intrinsic difficulty and present a reliable method to determine these magnitudes and their temperature dependencies in ru-1222(gd ) , through a systematic study of the hysteresis in the isotemperature magnetoresistance @xmath23 curves .
since no single crystals are available for this compound , polycrystalline materials were used in the present investigation . |
4,408 | Suppose that you have an abstract for a scientific paper: using chiral symmetry we investigate the leading su(3 ) violation in the complete set of quark twist-3 light - cone distribution functions of the pion , kaon , and eta , including the two - parton distributions @xmath0 , @xmath1 , and the three - parton distribution @xmath2 .
it is shown that terms non - analytic in the quark masses do not affect the shape , and only appear in the normalization constants .
predictive power is retained including the leading analytic @xmath3 operators . with the symmetry violating corrections
we derive useful model - independent relations between @xmath4 , @xmath5 , @xmath6 , and @xmath7
. we also comment on the calculations of the moments of these distributions using lattice qcd and light - cone sum rules . .
And you have already written the first three sentences of the full article: meson light cone distribution functions ( lcdfs ) play important roles in high energy hadronic exclusive processes @xcite .
the same lcdfs contribute in many processes relevant to measuring fundamental parameters of the standard model @xcite , such as @xmath8 which give the cabibbo - kobayashi - maskawa ( ckm ) quark - mixing matrix element @xmath9 , @xmath10 used for tagging , and @xmath11 which are important for measuring cp violation . with the increasing accuracy in data from the @xmath12 factories ,
the flavor dependence in lcdfs becomes important to understand the flavor symmetry breaking in processes like @xmath13 and @xmath14 , where @xmath15 and @xmath16 are pseudoscalar and vector mesons , respectively . in ref ..
Please generate the next two sentences of the article | @xcite , chiral perturbation theory ( chpt ) was first applied to study the leading su(3 ) symmetry breaking effects in twist-2 lcdfs @xmath17 .
it was shown that terms non - analytic in the quark masses do not affect the shape , and only appear in the normalization constants . furthermore , with the symmetry violating corrections useful model - independent relations between @xmath18 , @xmath19 , @xmath20 , and @xmath21 were derived . |
4,409 | Suppose that you have an abstract for a scientific paper: a statistical theory is presented which allows to calculate the stationary state achieved by a driven system after a process of collisionless relaxation .
the theory is applied to study an electron beam driven by an external electric field .
the vlasov equation with appropriate boundary conditions is solved analytically and compared with the molecular dynamics simulation .
a perfect agreement is found between the theory and the simulations . the full current - voltage phase diagram is constructed . .
And you have already written the first three sentences of the full article: unlike the equilibrium thermodynamics and statistical mechanics , which are well developed after the pioneering works of boltzmann and gibbs , our understanding of non - equilibrium thermodynamics is restricted to some special models and cases .
stochastic lattice gases have provided a fertile testing ground for studying non - equilibrium stationary states in driven systems @xcite .
these models exhibit a variety of phase transition arising from a diffusive ( collisional ) relaxation ..
Please generate the next two sentences of the article | for some of these models local equilibrium and hydrodynamic equations have been derived rigorously @xcite .
there are , however , other physical systems for which the approach to final stationary state is through a process of collisionless relaxation @xcite . gravitational systems and |
4,410 | Suppose that you have an abstract for a scientific paper: we investigate the magnetic and electronic properties of the gd@xmath0zn@xmath1 ( @xmath2 = fe and co ) compounds using x - ray resonant magnetic scattering ( xrms ) , x - ray absorption near - edge structure ( xanes ) and x - ray magnetic circular dichroism ( xmcd ) techniques .
the xrms measurements reveal that the gdco@xmath3zn@xmath1 compound has a commensurate antiferromagnetic spin structure with a magnetic propagation vector @xmath4 = @xmath5 below the nel temperature ( @xmath6 5.7 k ) .
only the gd ions carry a magnetic moment forming an antiferromagnetic structure with magnetic representation @xmath7 . for the ferromagnetic gdfe@xmath3zn@xmath1 compound ,
an extensive investigation was performed at low temperature and under magnetic field using xanes and xmcd techniques .
a strong xmcd signal of about 12.5 @xmath8 and 9.7 @xmath8 is observed below the curie temperature ( @xmath9 85 k ) at the gd-@xmath10 and @xmath11 edges , respectively .
in addition , a small magnetic signal of about 0.06 @xmath8 of the jump is recorded at the zn @xmath12-edge suggesting that the zn 4@xmath13 states are spin polarized by the gd 5@xmath14 extended orbitals . .
And you have already written the first three sentences of the full article: the demand for new materials with interesting and useful physical properties has led to a fast development in material science .
properties such as superconductivity , magnetic ordering , nearly ferromagnetic fermi - liquid and heavy fermion behavior have been observed in many materials , including the family of complex intermetallic compounds @xmath15zn@xmath1 ( @xmath16 = rare earth , @xmath2 = transition metal).@xcite this family , first reported two decades ago by nasch @xmath17.@xcite , has been extensively used as a model system due to its rather unique structure which features a complex but well ordered crystal structure .
the @xmath15zn@xmath1 compounds have a cubic structure with @xmath18 ( no ..
Please generate the next two sentences of the article | 227 ) space group in which the @xmath16 and @xmath2 ions occupy the crystallographic sites 8@xmath19 and 16@xmath14 , respectively . moreover , these ions are each encapsulated in quasi - spherical cages formed exclusively by zn ions , which occupy three inequivalent wyckoff positions given by 16@xmath20 , 48@xmath21 , and 96@xmath22 as can be viewed in fig . [
fig : fig0 ] . |
4,411 | Suppose that you have an abstract for a scientific paper: using both wavelet and fourier analysis , a study has been undertaken of the changes in the quasi - periodic variations in solar photospheric fields in the build - up to one of the deepest solar minima experienced in the past 100 years .
this unusual and deep solar minimum occurred between solar cycles 23 and 24 .
the study , carried out using ground based synoptic magnetograms spanning the period 1975.14 to 2009.86 , covered solar cycles 21 , 22 and 23 . a hemispheric asymmetry in periodicities of the photospheric fields
was seen only at latitudes above @xmath045@xmath1 when the data was divided , based on a wavelet analysis , into two parts : one prior to 1996 and the other after 1996 .
furthermore , the hemispheric asymmetry was observed to be confined to the latitude range 45@xmath1 to 60@xmath1 .
this can be attributed to the variations in polar surges that primarily depend on both the emergence of surface magnetic flux and varying solar surface flows .
the observed asymmetry when coupled with the fact that both solar fields above @xmath045@xmath1 and micro - turbulence levels in the inner - heliosphere have been decreasing since the early to mid nineties @xcite suggests that around this time active changes occurred in the solar dynamo that governs the underlying basic processes in the sun .
these changes in turn probably initiated the build - up to the very deep solar minimum at the end of the cycle 23 .
the decline in fields above @xmath045@xmath1 for well over a solar cycle , would imply that weak polar fields have been generated in the past two successive solar cycles _ viz .
_ cycles 22 and 23 . a continuation of this declining trend beyond 22 years ,
if it occurs , will have serious implications on our current understanding of the solar dynamo . .
And you have already written the first three sentences of the full article: the delayed onset of solar cycle 24 , after one of the deepest solar minimum experienced in the past 100 years has had significant solar and heliospheric consequences .
solar cycle 23 has been characterized by a steady decline in solar activity @xcite , a continuous weakening of polar fields @xcite and a decline in micro - turbulence levels in the inner heliosphere since @xmath21995 @xcite .
investigations of the boundary of polar coronal holes during the declining phase of solar cycle 23 using images from the extreme ultraviolet imaging telescope ( eit ) on board the solar heliospheric observatory ( soho ) , have found a decrease in coronal hole area by @xmath215@xmath3 in comparison to that at the beginning of solar cycle 23 @xcite . using both ground - based and space - borne observations of photospheric magnetic fields @xcite and theoretical modeling @xcite ,.
Please generate the next two sentences of the article | there have been continuous efforts to investigate and understand the behavior of solar photospheric fields and their correlation with meridional flows , to try and explain the delayed onset of cycle 24 and the cause of the deep minimum at the end of cycle 23 .
magnetic field measurements using data from the national solar observatory , kitt peak ( nso / kp ) synoptic magnetogram database , have shown that a decline in solar photospheric fields in the latitude range 45@xmath1 to 78@xmath1 began around the minimum of solar cycle 22 , in @xmath21995@xmath41996 @xcite . |
4,412 | Suppose that you have an abstract for a scientific paper: there have been many theoretical models constructed which aim to explain the neutrino masses and mixing patterns .
while many of the models will be eliminated once more accurate determinations of the mixing parameters , especially @xmath0 , are obtained , charged lepton flavor violation experiments are able to differentiate even further among the models . in this paper , we investigate various rare lepton flavor violation processes , such as @xmath1 and @xmath2 conversion , in five predictive supersymmetric ( susy ) @xmath3 models and their allowed soft - susy breaking parameter space in the constrained minimal susy standard model . utilizing the wilkinson microwave anisotropy probe dark matter constraints , we obtain lower bounds on the branching ratios of these rare processes and find that at least three of the five models we consider give rise to predictions for @xmath4 that will be tested by the meg collaboration at psi .
in addition , the next generation @xmath2 conversion experiment has sensitivity to the predictions of all five models , making it an even more robust way to test these models .
while generic studies have emphasized the dependence of the branching ratios of these rare processes on the reactor neutrino angle , @xmath5 , and the mass of the heaviest right - handed neutrino , @xmath6 , we find very massive @xmath6 is more significant than large @xmath5 in leading to branching ratios near to the present upper limits . .
And you have already written the first three sentences of the full article: the recent compilation of oscillation data from the atmospheric @xcite , reactor @xcite , and long baseline @xcite neutrino experiments has provided solid evidence that neutrinos have small but non - zero masses . a global fit
to current data gives the following @xmath7 limits for the mixing parameters @xcite , @xmath8 since then , the measurements of neutrino oscillation parameters have entered a precision era . on the other hand ,
as no information exists for the value of @xmath5 , the dirac or majorana nature of the neutrinos , the dirac and/or majorana cp phases , and the neutrino mass hierarchy , there are discoveries that are still yet to come . in the standard model ( sm ) , due to the lack of right - handed neutrinos and the conservation of lepton numbers , neutrinos are massless . to generate non - zero neutrino masses thus calls for physics beyond the sm ..
Please generate the next two sentences of the article | there have been many theoretical ideas proposed with an attempt to accommodate the experimentally observed small neutrino masses and the larger mixing angles among them . in ref .
@xcite , we have surveyed 63 models in the literature that are still viable candidates and have reasonably well - defined predictions for @xmath5 . we found that the predictions for @xmath9 of half of the models cover the range from 0.015 to the present upper bound of 0.13 . consequently , half of the models can be eliminated in the next generation of reactor experiments . |
4,413 | Suppose that you have an abstract for a scientific paper: in outburst sources , quasi - periodic oscillation ( qpo ) frequency is known to evolve in a certain way : in the rising phase , it monotonically goes up till a soft intermediate state is achieved . in the propagating oscillatory shock model , oscillation of the compton cloud
is thought to cause qpos .
thus , in order to increase qpo frequency , compton cloud must collapse steadily in the rising phase . in decline phases ,
exactly opposite should be true .
we investigate cause of this evolution of the compton cloud .
the same viscosity parameter which increases the keplerian disk rate , also moves the inner edge of the keplerian component , thereby reducing the size of the compton cloud and reducing the cooling time scale .
we show that cooling of the compton cloud by inverse comptonization is enough for it to collapse sufficiently so as to explain the qpo evolution .
in the two component advective flow ( tcaf ) configuration of chakrabarti - titarchuk , centrifugal force induced shock represents boundary of the compton cloud .
we take the rising phase of 2010 outburst of galactic black hole candidate h 1743 - 322 and find an estimation of variation of @xmath0 parameter of the sub - keplerian flow to be monotonically rising from @xmath1 to @xmath2 , well within the range suggested by magneto - rotational instability .
we also estimate the inward velocity of the compton cloud to be a few meters / second which is comparable to what is found in several earlier studies of our group by empirically fitting the shock locations with the time of observations . .
And you have already written the first three sentences of the full article: study of temporal variability including signatures of quasi - periodic oscillations ( qpos ) is an important aspect of astrophysics of black holes .
several models in the literature attempt to explain origin of low frequency qpos .
they include perturbation inside a keplerian disk @xcite , global disk oscillation @xcite , oscillation of wrapped disk @xcite , accretion ejection instability at the inner radius of a keplerian disk @xcite ..
Please generate the next two sentences of the article | @xcite , envisages a bounded region surrounding compact objects which is called the transition layer ( tl ) and identifies low frequency qpos as that associated with the viscous magneto - acoustic resonance oscillation of the bounded tl .
chakrabarti and his collaborators @xcite showed that the oscillations of centrifugal pressure supported accretion shocks @xcite could cause observed low frequency qpos . according to the two - component advective flow ( tcaf ) model @xcite |
4,414 | Suppose that you have an abstract for a scientific paper: let @xmath0 be a finite coxeter group acting linearly on @xmath1 . in this article we study support properties of @xmath0-invariant partial differential operator @xmath2 on @xmath1 with real analytic coefficients .
our assumption is that the principal symbol of @xmath2 has a special form , related to the root system corresponding to @xmath0 . in particular the zeros of the principal symbol
are supposed to be located on hyperplanes fixed by reflections in @xmath0 . we show that @xmath3 holds for all compactly supported smooth functions @xmath4 so that @xmath5 is @xmath0-invariant .
the main tools in the proof are holmgren s uniqueness theorem and some elementary convex geometry .
several examples and applications linked to the theory of special functions associated with root systems are presented . .
And you have already written the first three sentences of the full article: let @xmath2 be a linear partial differential operator on @xmath1 with constant coefficients .
then a classical theorem of lions and titchmarsch states that , for every distribution @xmath6 on @xmath1 with compact support , the convex hulls of the supports of @xmath7 and @xmath6 are equal : @xmath8 by regularization , this is equivalent to stating that for every compactly supported smooth function @xmath4 on @xmath1 , the convex hulls of the supports of @xmath9 and @xmath4 are equal : @xmath10 in fact , lions @xcite proved a more general version of the support theorem , namely @xmath11 we refer to @xcite for an elementary proof of this theorem .
the first version ( [ eq : supportconstantpdo ] ) obviously follows from the third one ( [ eq : suppconv ] ) by taking @xmath12 , the delta distribution at the origin ..
Please generate the next two sentences of the article | the comparison of the supports of @xmath4 and @xmath9 plays an important role at several places in analysis .
one typical situation is the study of solvability of differential operators . |
4,415 | Suppose that you have an abstract for a scientific paper: @xmath0ne has been known as a typical example of a nucleus with @xmath1 cluster structure ( @xmath2o+@xmath1 structure ) . however according to the spherical shell model , the spin - orbit interaction acts attractively for four nucleons outside of the @xmath2o core , and this spin - orbit effect can not be taken into account in the simple @xmath1 cluster models .
we investigate how the @xmath1 cluster structure competes with independent particle motions of these four nucleons . the antisymmetrized quasi - cluster model ( aqcm )
is a method to describe a transition from the @xmath1 cluster wave function to the @xmath3-coupling shell model wave function . in this model ,
the cluster - shell transition is characterized by only two parameters ; @xmath4 representing the distance between clusters and @xmath5 describing the breaking of @xmath1 clusters , and the contribution of the spin - orbit interaction , very important in the @xmath3-coupling shell model , can be taken into account by changing @xmath1 clusters to quasi clusters . in this article ,
based on aqcm , we apply @xmath2o plus one quasi cluster model for @xmath0ne . here
we focus on the @xmath6 transition matrix element , which has been known as the quantity characterizing the cluster structure .
the @xmath6 transition matrix elements are sensitive to the change of the wave functions from @xmath1 cluster to @xmath3-coupling shell model . .
And you have already written the first three sentences of the full article: @xmath0ne has been known as a typical example of a nucleus which has @xmath1 cluster structure .
there have been numerous works based on the cluster model , which explain the observed doublet rotational band structure .
in addition to the ground @xmath7 band , the negative parity band ( @xmath8 ) starting with the @xmath9 state at @xmath10 mev has been observed , and existence of this `` low - lying '' negative parity band is the strong evidence that simple spherical mean field is broken ..
Please generate the next two sentences of the article | these bands are well explained by the picture that @xmath1 cluster is located at some distance from the @xmath2o core @xcite .
recently `` container picture '' has been proposed to describe the non - localization of the @xmath1 cluster around @xmath2o @xcite . however , according to the shell model , four nucleons perform independent particle motions around the @xmath2o core , which has doubly closed shell of the @xmath11 shell , and the spin - orbit interaction acts attractively to them . |
4,416 | Suppose that you have an abstract for a scientific paper: we study the coupling induced destabilization in an array of identical oscillators coupled in a ring structure where the number of oscillators in the ring is large .
the coupling structure includes different types of interactions with several next neighbors .
we derive an amplitude equation of ginzburg - landau type , which describes the destabilization of a uniform stationary state in a ring with a large number of nodes . applying these results to unidirectionally coupled duffing oscillators
, we explain the phenomenon of a fast transition to chaos , which has been numerically observed in such systems .
more specifically , the transition to chaos occurs on an interval of a generic control parameter that scales as the inverse square of the size of the ring , i.e. for sufficiently large system , we observe practically an immediate transition to chaos . 34c15 , 34c23 , 34c28 , 37g35 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _....
And you have already written the first three sentences of the full article: networks of coupled oscillators have been the subject of extensive research in the last decade .
coupled systems can display a huge variety of dynamical phenomena , starting from synchronization phenomena in various types of inhomogeneous or irregular networks , up to complex collective behavior , such as for example various forms of phase transitions , traveling waves @xcite , phase - locked patterns , amplitude death states @xcite , or so called chimera states that display a regular pattern of coherent and incoherent motion @xcite .
of particular interest are situations , where complex spatio - temporal structures can emerge in regular arrays of identical units induced only by the coupling interaction . in many cases ,.
Please generate the next two sentences of the article | the resulting phenomena differ substantially from corresponding situations in continuous media @xcite and depend strongly on the underlying network topology .
our specific interest is in the emergence of spatio - temporal structures in a homogeneous array of identical units that have a stable uniform equilibrium at which the coupling vanishes . as a classical paradigm , |
4,417 | Suppose that you have an abstract for a scientific paper: inflationary predictions of the cosmic microwave background anisotropy are often based on the slow - roll approximation .
we study the precision of these predictions and compare them with the recent data from boomerang and maxima-1 . .
And you have already written the first three sentences of the full article: high quality measurements of anisotropies in the cosmic microwave background ( cmb ) probe the cosmic fluctuations generated during an inflationary epoch in the very early universe @xcite . recently ,
boomerang @xcite and maxima @xcite teams announced the clear detection of a first acoustic peak at an angular scale @xmath0 , which confirms the most important prediction of inflation : the universe seems to be spatially flat @xcite .
another generic prediction of inflation is that the primordial spectra of density perturbations and gravitational waves are _ almost _ scale - invariant ..
Please generate the next two sentences of the article | more cmb precision measurements will be available soon .
we argue @xcite that cmb predictions on the basis of the simplest inflationary model , slow - roll inflation @xcite , are not as precise as could be believed from the accuracy of the power spectra @xcite . |
4,418 | Suppose that you have an abstract for a scientific paper: we show that early stellar encounters can explain the high eccentricities and inclinations observed in the outer part ( @xmath0au ) of the edgeworth - kuiper belt ( ekb ) .
we consider the proto - sun as a member of a stellar aggregation that undergoes dissolution on a timescale @xmath1 yrs , such that the solar nebula experiences a flyby encounter at pericenter distance ( @xmath2 ) on the order of @xmath3au .
using numerical simulations we show that a stellar encounter pumps the velocity dispersion in the young solar nebula in the outer parts . in the case of a nearly parabolic encounter with a solar - mass companion the velocity dispersion at @xmath4
is pumped up to such an extent that collisions between planetesimals would be expected to become highly disruptive , halting further growth of planetesimals .
this has the consequence that planet formation is forestalled in that region .
we also find that a stellar encounter with pericenter distance @xmath5@xmath6au could have pumped up the velocity dispersion of ekb objects outside 42au to the observed magnitude while preserving that inside neptune s 3:2 mean - motion resonance ( located at 39.5au ) .
this allows for the efficient capture of objects by the resonance during a phase of orbital migration by proto - neptune , which we also test with simulations .
we point out that such a stellar encounter generally affects the dynamical and material structure of a protoplanetary disk and the planetesimal distribution can remain imprinted with this signature over much of the main sequence lifetime of the star . in particular , our results support the notion that an analogous process has operated in some recently observed extrasolar dust disks . .
And you have already written the first three sentences of the full article: stars commonly form in groups or clusters within turbulent molecular clouds on timescales which are of about a million years ( hillenbrand 1997 ) .
typical young stellar aggregates have sizes of roughly 1 pc and consist of a few hundred stars .
recent observations have also shown that most stars form in eccentric binary systems and that the binary frequency of young stars is about two times higher than that of main sequence stars in the solar neighbourhood ( ghez et al ..
Please generate the next two sentences of the article | 1997 , khler & leinert 1998 ) .
this reflects the fact that secular dynamical processes within newly formed stellar groups tend to reduce their binary fraction over time . |
4,419 | Suppose that you have an abstract for a scientific paper: on modern large - scale parallel computers , the performance of krylov subspace iterative methods is limited by global synchronization .
this has inspired the development of @xmath0-step ( or communication - avoiding ) krylov subspace method variants , in which iterations are computed in blocks of @xmath0 .
this reformulation can reduce the number of global synchronizations per iteration by a factor of @xmath1 , and has been shown to produce speedups in practical settings .
although the @xmath0-step variants are mathematically equivalent to their classical counterparts , they can behave quite differently in finite precision depending on the parameter @xmath0 .
if @xmath0 is chosen too large , the @xmath0-step method can suffer a convergence delay and a decrease in attainable accuracy relative to the classical method .
this makes it difficult for a potential user of such methods - the @xmath0 value that minimizes the time per iteration may not be the best @xmath0 for minimizing the overall time - to - solution , and further may cause an unacceptable decrease in accuracy . towards improving the reliability and usability of @xmath0-step krylov subspace methods , in this work
we derive the _ adaptive @xmath0-step cg method _
, a variable @xmath0-step cg method where in block @xmath2 , the parameter @xmath3 is determined automatically such that a user - specified accuracy is attainable . the method for determining @xmath3
is based on a bound on growth of the residual gap within block @xmath2 , from which we derive a constraint on the condition numbers of the computed @xmath4-dimensional krylov subspace bases .
the computations required for determining the block size @xmath3 can be performed without increasing the number of global synchronizations per block .
our numerical experiments demonstrate that the adaptive @xmath0-step cg method is able to attain up to the same accuracy as classical cg while still significantly reducing the total number of global synchronizations . .
And you have already written the first three sentences of the full article: in this paper , we consider the use of krylov subspace methods for solving large , sparse linear systems @xmath5 , where @xmath6 .
we will focus on the conjugate gradient ( cg ) method @xcite , which is used when @xmath7 is symmetric positive definite .
given an initial approximate solution @xmath8 and corresponding residual @xmath9 , the cg method iteratively updates the approximate solution using a sequence of nested krylov subspaces @xmath10 , where @xmath11 denotes the @xmath12-dimension krylov subspace with matrix @xmath7 and starting vector @xmath13 . in iteration @xmath12 , the updated approximate solution @xmath14 is chosen by imposing the galerkin condition @xmath15 ..
Please generate the next two sentences of the article | thus each iteration of cg requires a matrix - vector product with @xmath7 in order to expand the dimension of the krylov subspace and a number of inner products to perform the orthogonalization . on modern computer architectures ,
the speed with which the matrix - vector products and inner products can be computed is limited by communication ( i.e. , the movement of data ) . |
4,420 | Suppose that you have an abstract for a scientific paper: the approach for a network behavior description in terms of numerical time - dependant functions of the protocol parameters is suggested .
this provides a basis for application of methods of mathematical and theoretical physics for information flow analysis on network and for extraction of patterns of typical network behavior .
the information traffic can be described as a trajectory in multi - dimensional parameter - time space with dimension about 10 - 12 .
based on this study some algorithms for the proposed intrusion detection system are discussed .
network monitoring , intrusion detection , information flow .
And you have already written the first three sentences of the full article: information systems are threatened today as never before .
evolving network technologies have provided powerful information - transfer applications that have increased our reliance on computerized information systems at the same time that public access to the internet has increased the number and sophistication of those who seek to compromise these systems .
the diversity of existing software are hardware devices make the problem of the network the protection very more difficult ..
Please generate the next two sentences of the article | there are many approaches to study the attack tolerance of networks .
these approaches usually include the study of dependance of the network stability on the network complexity and topology ( see , for example @xcite and references therein ) , and signature - based analysis technique and statistical analysis and modelling of network traffic ( see , for example @xcite ) . some methods to study spatial traffic flows traversing the network @xcite and correlation functions of irregular sequences of numbers occurring in the operation of computer networks @xcite have been proposed recently . |
4,421 | Suppose that you have an abstract for a scientific paper: we address the ability of broad iron emission lines from black hole accretion disks to diagnose the spin of the black hole . using a high - resolution 3-dimensional mhd simulation of a geometrically - thin accretion disk in a pseudo - newtonian potential
, we show that both the midplane density and the vertical column density of the accretion flow drop dramatically over a narrow range of radii close to the innermost stable circular orbit ( isco ) .
we argue that this drop of density is accompanied by a sharp increase in the ionization parameter of the x - ray photosphere , and that the resulting imprint of the isco on the x - ray reflection spectrum can be used to constrain spin .
motivated by this simulation , we construct a simplified toy - model of the accretion flow within the isco of a kerr black hole , and use this model to estimate the systematic error on inferred black hole spin that may result from slight bleeding of the iron line emission to the region inside of the isco .
we find that these systematic errors can be significant for slowly spinning black holes but become appreciably smaller as one considers more rapidly rotating black holes . .
And you have already written the first three sentences of the full article: recent years have brought an increasing realization of the astrophysical importance of black hole spin .
ever since the seminal work of penrose ( 1969 ) and blandford & znajek ( 1977 ) , it has been recognized that black hole spin may be an important source of energy , especially for the powerful relativistic jets seen emerging from many black hole systems .
however , the importance of black hole spin goes beyond its role as a possible power source ..
Please generate the next two sentences of the article | the spins of stellar - mass black holes found in accreting galactic black hole binaries ( gbhbs ) are expected to be natal ( king & kolb 1999 ) and give us a window into the black hole forming core - collapse supernova .
the spin distribution of the supermassive black hole ( smbh ) population ( and its dependence on smbh mass ) encodes the black hole growth history , e.g. , the role of accretion versus mergers ( moderski & sikora 1996 ; volonteri et al . 2005 ) . |
4,422 | Suppose that you have an abstract for a scientific paper: in this paper we study the rank one discrete valuations of @xmath0 whose center in @xmath1\kern - 1.8pt ] } } $ ] is the maximal ideal @xmath2 . in sections 2 to 6
we give a construction of a system of parametric equations describing such valuations .
this amounts to finding a parameter and a field of coefficients .
we devote section 2 to finding an element of value 1 , that is , a parameter .
the field of coefficients is the residue field of the valuation , and it is given in section 5 .
the constructions given in these sections are not effective in the general case , because we need either to use the zorn s lemma or to know explicitly a section @xmath3 of the natural homomorphism @xmath4 between the ring and the residue field of the valuation @xmath5 .
however , as a consequence of this construction , in section 7 , we prove that @xmath6 can be embedded into a field @xmath7 , where the _ `` extended valuation '' is as close as possible to the usual order function_. valuation theory , local uniformization , formal power rings , completions .
13f25 , 13f30 , 14b05 , 16w60 .
And you have already written the first three sentences of the full article: let @xmath8 be an algebraically closed field of characteristic 0 , @xmath9\kern - 1.8pt ] } } $ ] , @xmath10 its maximal ideal and @xmath11 its quotient field .
let @xmath5 be a rank - one discrete valuation of @xmath12 , @xmath13 the valuation ring , @xmath14 the maximal ideal and @xmath15 the residue field of @xmath5 .
the center of @xmath5 in @xmath16 is @xmath17 . throughout this paper discrete valuation of @xmath12.
Please generate the next two sentences of the article | " means rank - one discrete valuation of @xmath12 whose center in @xmath16 is the maximal ideal @xmath18 " .
the dimension of @xmath5 is the transcendence degree of @xmath15 over @xmath8 . in order to simplify the redaction |
4,423 | Suppose that you have an abstract for a scientific paper: we develop and implement an algorithm for the quantitative characterization of cluster dynamics occurring on cellular automata defined on an arbitrary structure . as a prototype for such systems we focus on the ising model on a finite sierpsinski gasket , which is known to possess a complex thermodynamic behavior .
our algorithm requires the projection of evolving configurations into an appropriate partition space , where an information - based metrics ( rohlin distance ) can be naturally defined and worked out in order to detect the changing and the stable components of clusters .
the analysis highlights the existence of different temperature regimes according to the size and the rate of change of clusters .
such regimes are , in turn , related to the correlation length and the emerging `` critical '' fluctuations , in agreement with previous thermodynamic analysis , hence providing a non - trivial geometric description of the peculiar critical - like behavior exhibited by the system . moreover , at high temperatures , we highlight the existence of different time scales controlling the evolution towards chaos .
+ _ keywords _ : dynamical processes ( theory ) , classical phase transitions ( theory ) , classical monte carlo simulations .
And you have already written the first three sentences of the full article: the effect of inhomogeneity on the critical behaviour of magnetic systems has been considered in various contexts ( e.g. disorder , coupling randomness , quasiperiodic structures ) ; in particular , discrete - spin models defined on fractal topologies possess critical properties significantly different and richer than those found for translationally invariant systems @xcite .
the interest in fractal structures is not purely theoretical : many condensed - matter systems display strong nonuniformity on all length scales and can therefore be characterized as fractal objects ; examples include the backbone of percolation clusters , aggregates obtained from diffusion - limited growth processes , and absorbent surfaces .
one of the most known fractals is the sierpinski gasket ( sg ) , which , due to its exact decimability , allows analytical approaches ; in particular , by means of renormalization group techniques , it was proved that the ising model on the sg exhibits phase transition only at zero temperature , while at any finite temperature the system breaks into domains and loses long - range order @xcite . while this result was found in the thermodynamic limit , at the mesoscopic sizes peculiar and interesting thermodynamic properties arise @xcite ..
Please generate the next two sentences of the article | more precisely , the ising model defined on a finite sg exhibits critical - like features at nonzero , low temperatures and the solution found in the thermodynamic limit turns out to be a poor approximation .
this anomalous behavior has been investigated from a thermodynamic point of view and derives from long - range , slowly decaying correlations at low temperatures @xcite . |
4,424 | Suppose that you have an abstract for a scientific paper: by using a suitable set of the surface energy coefficient , nuclear radius , and universal function , the original proximity potential 1977 is modified .
the overestimate of the data by 4% reported in the literature is significantly reduced .
our modified proximity potential reproduces the experimental data nicely compared to its older versions . .
And you have already written the first three sentences of the full article: recently , great theoretical and experimental efforts are taken to studying the fusion of heavy nuclei leading to several new phenomena including the understanding of the formation of neutron -rich and super heavy elements @xcite .
the precise knowledge of the interaction potential between two nuclei is a difficult task and continuing efforts are needed in this direction .
this problem has been of very active research over the last three decades and remains one of the most widely studied subject in low - energy heavy - ion physics @xcite ..
Please generate the next two sentences of the article | the total interaction potential is sum of the long range coulomb repulsive force and short range nuclear attractive force .
the coulomb part of the interaction potential is well - known , whereas nuclear part is not clearly understood . |
4,425 | Suppose that you have an abstract for a scientific paper: we have studied the two - body production and decay of a heavy , right - handed neutrino to two light states using the full boltzmann equation instead of the usual integrated boltzmann equation which assumes kinetic equilibrium of all species .
decays and inverse decays are inefficient for thermalising the distribution function of the heavy neutrino and in some parameter ranges there can be very large deviations from kinetic equilibrium .
this leads to substantial numerical differences between the two approaches .
furthermore we study the impact of this difference on the lepton asymmetry production during leptogenesis and find that in the strong washout regime the final asymmetry is changed by 15 - 30% when the full boltzmann equation is used . .
And you have already written the first three sentences of the full article: leptogenesis is perhaps the most attractive model for generating the matter - antimatter asymmetry in our universe @xcite after inflation .
the process generates a lepton asymmetry via the production and subsequent decay of a heavy majorana neutrino .
this lepton asymmetry is partially converted to a baryon asymmetry via sphaleron processes @xcite which break both @xmath0 and @xmath1 , but conserve @xmath2 ..
Please generate the next two sentences of the article | the fraction of @xmath2 that ends up in @xmath0 by the sphaleron processes is given by @xmath3 giving @xmath4 where the @xmath5 is created by leptogenesis which gives a non zero value of @xmath1 ( see for instance @xcite ) .
in its simplest form ( within the context of the see - saw model ) leptogenesis consists of adding three heavy right - handed neutrinos to the standard model . in the hierarchical limit one of these right handed neutrinos , @xmath6 , |
4,426 | Suppose that you have an abstract for a scientific paper: we investigate numerically the combined effects of supersonic turbulence , strong magnetic fields and ambipolar diffusion on cloud evolution leading to star formation .
we find that , in clouds that are initially magnetically subcritical , supersonic turbulence can speed up star formation , through enhanced ambipolar diffusion in shocks .
the speedup overcomes a major objection to the standard scenario of low - mass star formation involving ambipolar diffusion , since the diffusion time scale at the average density of a molecular cloud is typically longer than the cloud life time . at the same time
, the strong magnetic field can prevent the large - scale supersonic turbulence from converting most of the cloud mass into stars in one ( short ) turbulence crossing time , and thus alleviate the high efficiency problem associated with the turbulence - controlled picture for low - mass star formation .
we propose that relatively rapid but inefficient star formation results from supersonic collisions of somewhat subcritical gas in strongly magnetized , turbulent clouds .
the salient features of this shock - accelerated , ambipolar diffusion - regulated scenario are demonstrated with numerical experiments . .
And you have already written the first three sentences of the full article: the standard scenario of low - mass star formation envisions quasi - static condensation of dense cores out of magnetically subcritical clouds and inside - out core collapse leading to star formation ( shu , adams & lizano 1987 ; mouschovias & ciolek 1999 ) .
an alternative is the turbulence - controlled star formation , with magnetic fields playing a minor role if any ( larson 1981 ; mac low & klessen 2004 ) . in this picture , dense cores arise from compression in the supersonic turbulence observed in molecular clouds ( padoan et al . 2001 ; gammie et al . 2003 ; li et al . 2003 ) .
the cores so formed are transient entities , however . even though some of them may have column density distributions resembling those of static bonnor - ebert spheres , their internal motions are typically dynamic , with transonic or even supersonic speeds ( ballesteros - paredes , klessen , & vzquez - semadeni 2003 ) which are difficult to reconcile with the subsonic internal motions inferred in low - mass starless cores ( lee , myers & tafalla 1999 ) ..
Please generate the next two sentences of the article | a potentially more serious difficulty with this picture is the rate and efficiency of star formation .
numerical simulations have shown that supersonic turbulence decays in one free - fall time or less , with or without a strong magnetization ( mac low et al . |
4,427 | Suppose that you have an abstract for a scientific paper: the teukolsky formalism of black hole perturbation theory describes weak gravitational radiation generated by a mildly dynamical hole near equilibrium .
a particular null tetrad of the background kerr geometry , due to kinnersley , plays a singularly important role within this formalism . in order to apply the rich physical intuition of teukolsky s approach to the results of fully non - linear numerical simulations
, one must approximate this kinnersley tetrad using raw numerical data , with no _ a priori _ knowledge of a background .
this paper addresses this issue by identifying the directions of the tetrad fields in a quasi - kinnersley frame .
this frame provides a unique , analytic extension of kinnersley s definition for the kerr geometry to a much broader class of space - times including not only arbitrary perturbations , but also many examples which differ non - perturbatively from kerr .
this paper establishes concrete limits delineating this class and outlines a scheme to calculate the quasi - kinnersley frame in numerical codes based on the initial - value formulation of geometrodynamics . .
And you have already written the first three sentences of the full article: after an early history marked by vigorous debate ( see , e.g. , @xcite ) , the existence of gravitational radiation has become accepted as a hallmark prediction of einstein s general theory of relativity . despite indirect evidence supporting this prediction , however , gravitational waves have yet to be observed directly . indeed , rough ,
order - of - magnitude calculations indicate a typical passing wave will produce only tiny material strains of order @xmath0 . a new generation of laser - interferometric gravitational wave observatories
have recently been commissioned , and several are already operational , which aim to observe such strains @xcite and thereby detect gravitational waves incident on earth ..
Please generate the next two sentences of the article | these experiments are necessarily extremely delicate and , as a result , both initial detection and the long - term goal of extracting new information about the distant sources of a particular gravitational wave must be aided by detailed theoretical predictions .
a community of theorists have turned to numerical simulations of the full , non - linear einstein equations to identify the characteristic features of the gravitational radiation generated by various sources . |
4,428 | Suppose that you have an abstract for a scientific paper: we apply the stellar population synthesis code by cid fernandes et al .
to model the stellar contribution for a sample of 209 type ii agns at @xmath0 from the sloan digital sky survey .
the reliable stellar velocity dispersions ( @xmath1 ) are obtained for 33 type ii agns with significant stellar absorption features . according to the @xmath2}$ ] criterion of @xmath3 , 20 of which
can be classified as type ii quasars .
we use the formula of greene & ho to obtain the corrected stellar velocity dispersions ( @xmath4 ) .
we also calculate the supermassive black holes masses from @xmath4 in these high - redshift type ii agns .
the [ o iii ] luminosity is correlated with the black hole mass ( although no correlation between the extinction - corrected [ o iii ] luminosity and the black hole mass ) , and no correlation is found between the eddington ratio and the [ o iii ] luminosity or the corrected [ o iii ] luminosity .
three sets of two - component profile are used to fit multiple emission transitions ( [ o iii]@xmath54959 , 5007 and [ o ii]@xmath53727 , 3729 ) in these 33 stellar - light subtracted spectra .
we also measure the gas velocity dispersion ( @xmath6 ) from these multiple transitions , and find that the relation between @xmath6 and @xmath4 becomes much weaker at higher redshifts than in smaller redshifts .
the distribution of @xmath7 is @xmath8 for the core [ o iii ] line and @xmath9 for the [ o ii ] line , which suggests that @xmath6 of the core [ o iii ] and [ o ii ] lines can trace @xmath4 within about 0.1 dex in the logarithm of @xmath4 . for the secondary driver , we find that the deviation of @xmath6 from @xmath4 is correlated with the eddington ratio .
galaxies : active galaxies : nuclei quasars : emission lines .
And you have already written the first three sentences of the full article: recent advances in the study of normal galaxies and active galactic nuclei ( agns ) are ample observational evidence for the existence of central supermassive black holes ( smbhs ) and the relationship between smbhs and bulge properties of host galaxies ( gebhardt et al . 2000 ;
ferrarese & merritt 2000 ; tremaine et al .
2002 ; begelman 2003 ; shen et al ..
Please generate the next two sentences of the article | we can use the stellar and/or gaseous dynamics to derive the smbhs masses in nearby inactive galaxies .
however , it is much more difficult for the case of agns . with the broad emission lines from broad - line regions ( blrs)(e.g . |
4,429 | Suppose that you have an abstract for a scientific paper: we examine the properties of 18 long period ( @xmath0 days ) and very luminous ( median absolute magnitude of m@xmath1 and m@xmath2 ) cepheids to see if they can serve as an useful distance indicator .
we find that these ultra long period ( ulp ) cepheids have a relatively shallow period - luminosity ( pl ) relation , so in fact they are more `` standard candle''-like than classical cepheids . in the reddening - free wesenheit index ,
the slope of the ulp pl relation is consistent with zero .
the scatter of our sample about the w@xmath3 pl relation is @xmath4 mag , approaching that of classical cepheids and type ia supernovae .
we expect this scatter to decrease as bigger and more uniform samples of ulp cepheids are obtained .
we also measure a non - zero period derivative for one ulp cepheid ( smc hv829 ) and use the result to probe evolutionary models and mass loss of massive stars .
ulp cepheids main advantage over classical cepheids is that they are more luminous , and as such show great potential as stellar distance indicators to galaxies up to @xmath5 mpc and beyond . .
And you have already written the first three sentences of the full article: a reliable method of measuring the physical distance to astrophysical objects has always been sought after in observational astronomy ( e.g. , * ? ? ? * ) . in the era of `` precision cosmology '' , the need for accurate physical distance measurements has been amplified ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | accurate and precise distance indicators hold the key to pinning down the value of the hubble constant @xmath6 and many other cosmological parameters ( see discussion in , e.g. , * ? ? ?
a number of methods have been employed to determine extragalactic distances , with varying degree of success ( e.g. , * ? ? ? |
4,430 | Suppose that you have an abstract for a scientific paper: supernovae play a large but poorly understood role in our attempts to explain the evolution of the baryonic universe .
numerous observations throughout astronomy can not be explained if we neglect their influence , yet our quantitative understanding of the ways in which supernovae affect the universe remains remarkably poor .
this is one of the most embarrassing gaps in our knowledge of the cosmos , and planned telescopes and surveys will probably not do much to fill it .
the problem is that these surveys will be optimized to observe galaxies and intergalactic material independently of each other , while ( in the author s view ) by far the best information will come from simultaneous surveys of galaxies and the intergalactic material ( igm ) in their vicinity .
only this will show directly how galaxies affect their surroundings and provide a rough energy scale for supernova - driven winds .
redshifts @xmath0 are ideal for the joint galaxy / igm surveys we advocate , because the comoving density of star formation is near its peak , because the lyman-@xmath1 forest is thin enough for qso spectra to reveal the locations of the dominant metallic species , and because bright background qsos are common . but a new uv - capable spectrograph in space will be required .
journalnameasp conference series @holderastronomical society of the pacific jourvol000 @year2002 @titlehubble s science legacy : future optical - ultraviolet astronomy from space @authork.r .
sembach , j.c .
blades , g.d .
illingworth , r.c .
kennicutt ( eds . )
slug @ [ cols= " < " , ] ps .
@paspcstitlemkbothgobbletwo oddhead oddfoot evenheadoddheadevenfootoddfoot ps .
@myheadingsmkbothgobbletwo oddhead__oddfootevenhead__evenfoot##1##1 leftmark#1#2@upcase#1 rightmark#1#2@upcase#2 # 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: fifteen years from now we will be awash in galaxies .
2df , sloan , and maybe a sloan successor will have given us redshifts for more than a million galaxies in the nearby universe .
deep and vvds will have added @xmath2 galaxies out to redshift @xmath3 ..
Please generate the next two sentences of the article | ngst and 30 m optical / ir telescopes on the ground may have detected thousands of galaxies to @xmath4some of the first sources of light in the universe .
these surveys and others will teach us a tremendous amount about galaxy and structure formation . |
4,431 | Suppose that you have an abstract for a scientific paper: the sao / nasa astrophysics data system ( ads ) grew up with and has been riding the waves of the information age , closely monitoring and anticipating the needs of its end - users .
by now , all professional astronomers are using the ads on a daily basis , and a substantial fraction have been using it for their entire professional career .
in addition to being an indispensable tool for professional scientists , the ads also moved into the public domain , as a tool for science education . in this paper
we will highlight and discuss some aspects indicative of the impact the ads has had on research and the access to scholarly publications .
the ads is funded by nasa grant nnx09ab39 g .
keywords : digital libraries ; sao / nasa astrophysics data system ; societal impact .
And you have already written the first three sentences of the full article: why do scientists publish ? first and foremost , because they want to share their findings and further science .
essential to this process is the ability for other people to ( efficiently ) discover these publications .
the process of information discovery has changed dramatically over the last two decades ..
Please generate the next two sentences of the article | remember the days of spending hours in a library , paging through a&a abstracts , catalogs and tables of contents ? sometimes a publication had to be retrieved via inter library loan , adding more time to the discovery process .
a lengthy discovery process not only means a long journey before finally acquiring enough fuel to set the first step towards your goal , it also means that the discovery process is a significant portion of the cost of employing a scientist . |
4,432 | Suppose that you have an abstract for a scientific paper: the pulsating da white dwarfs ( zz ceti stars ) are @xmath0-mode non - radial pulsators .
asteroseismology provides strong constraints on their global parameters and internal structure . since all the da white dwarfs falling in the zz ceti instability strip
do pulsate , the internal structure derived from asteroseismology brings knowledge for the da white dwarfs as a whole group .
hs 0507 + 0434b is one of the zz ceti stars which lies approximately in the middle of the instability strip for which we have undertaken a detailed asteroseismological study .
we carried out multisite observation campaigns in 2007 and from december 2009 to january 2010 . in total , 206 hours of photometric time - series have been collected .
they have been analysed by means of fourier analysis and simultaneous multi - frequency sine - wave fitting . in total , 39 frequency values are resolved including 6 triplets and a number of linear combinations .
we identify the triplets as @xmath1=1 @xmath0-modes split by rotation .
we derived the period spacing , the rotational splitting and the rotation rate . from the comparison of the observed periods with the theoretical periods of a series of models we estimate the fundamental parameters of the star : its total mass m@xmath2/m@xmath3 = 0.675 , its luminosity l / l@xmath3=3.5@xmath4 , and its hydrogen mass fraction m@xmath5/m@xmath2= 10@xmath6 .
[ firstpage ] stars : white dwarfs stars : oscillations stars : individual : hs 0507 + 0434b . .
And you have already written the first three sentences of the full article: as the end products of about 97% of the stars of the galaxy , white dwarf stars offer important clues about their prior evolutionary history .
they also provide potentially the age of the galactic disk and of the globular clusters they belong to ( winget et al . 1987 ; harris et al .
2006 ) through the age that can be estimated from cooling sequences ( ruiz & bergeron 2001 ) ..
Please generate the next two sentences of the article | however , determining the age of a white dwarf on its cooling sequence requires knowing its fundamental parameters : the total mass , the effective temperature , the luminosity , the fractional mass of the hydrogen and/or the helium outer layers , the core composition , etc .
asteroseismology of white dwarfs provides a unique tool to explore their internal structure and determine those fundamental parameters . |
4,433 | Suppose that you have an abstract for a scientific paper: the spectrum of meson and diquark excitations of dense quark matter is considered in the framework of the nambu jona - lasinio model with three types of massless quarks in the presense of a quark number chemical potential @xmath0 .
we investigate the effective action of meson- and diquark fields both at sufficiently large values of @xmath1 mev , where the color flavor locked ( cfl ) phase is realized , and in the chirally broken phase of quark matter ( @xmath2 ) . in the last case all nine pseudoscalar mesons are nambu
goldstone ( ng ) bosons , whereas the mass of the scalar meson nonet is twice the dynamical quark mass . in the chirally broken phase
the pseudoscalar diquarks are not allowed to exist as stable particles , but the scalar diquarks might be stable only at a rather strong interaction in the diquark channel . in the case of the cfl phase ,
all ng bosons of the model are realized as scalar and pseudoscalar diquarks .
moreover , it turns out that massive diquark excitations are unstable for this phase . in particular , for the scalar and pseudoscalar octets of diquark resonances a mass value around 230 mev was found numerically .
in contrast , mesons are stable particles in the cfl phase .
their masses lie in the interval 400@xmath3500 mev for not too large values of @xmath4 . .
And you have already written the first three sentences of the full article: it is well - known that at asymptotically high baryon densities the ground state of massless three - flavor qcd corresponds to the so - called color
flavor locked ( cfl ) phase @xcite . in this phase quarks of all three flavors as well as three colors undergo pairing near the fermi surface due to the attractive one - gluon exchange potential .
the properties of different collective modes , including nambu goldstone ( ng ) bosons , of the cfl phase were studied already in the framework of weak - coupling qcd @xcite . at intermediate baryon densities , related to compact star physics ,.
Please generate the next two sentences of the article | weak - coupling expansion of qcd is not applicable , so the description of color superconductivity , including the cfl phase , is more adequate in the framework of effective theories for the low energy qcd region . in particular ,
since massless excitations might play an important role in different transport phenomena , such as cooling processes of neutron stars etc , different chiral type effective theories for the pseudoscalar ng bosons of the cfl phase are usually used ( see , e.g. , @xcite ) . |
4,434 | Suppose that you have an abstract for a scientific paper: we study protoplanetary disc evolution assuming that angular momentum transport is driven by gravitational instability at large radii , and magnetohydrodynamic ( mhd ) turbulence in the hot inner regions . at radii of the order of 1 au such discs develop a magnetically layered structure , with accretion occurring in an ionized surface layer overlying quiescent gas that is too cool to sustain mhd turbulence .
we show that layered discs are subject to a limit cycle instability , in which accretion onto the protostar occurs in @xmath0 bursts with @xmath1 , separated by quiescent intervals lasting @xmath2 where @xmath3 .
such bursts could lead to repeated episodes of strong mass outflow in young stellar objects .
the transition to this episodic mode of accretion occurs at an early epoch ( @xmath4 ) , and the model therefore predicts that many young pre - main - sequence stars should have low rates of accretion through the inner disc . at ages of a few myr , the discs are up to an order of magnitude more massive than the minimum mass solar nebula , with most of the mass locked up in the quiescent layer of the disc at @xmath5 .
the predicted rate of low mass planetary migration is reduced at the outer edge of the layered disc , which could lead to an enhanced probability of giant planet formation at radii of 1 3 au .
psfig accretion , accretion discs mhd stars : pre - main - sequence stars : formation solar system : formation planets and satellites .
And you have already written the first three sentences of the full article: the structure and evolution of protoplanetary discs depend upon the rate at which gas can shed its angular momentum and thereby flow inwards .
two widely applicable physical mechanisms are known to lead to the required outward angular momentum transport . if the gas is coupled to a magnetic field , instabilities that inevitably arise in differentially rotating discs ( balbus & hawley 1991 ; chandrasekhar 1961 ; velikhov 1959 ) lead to turbulence and angular momentum transport ( stone et al .
1996 ; brandenburg et al . 1995 ; for a review see e.g. hawley & balbus 1999 ) ..
Please generate the next two sentences of the article | if the disc is massive enough , gravitational instability leads to additional transport ( toomre 1964 ; laughlin & bodenheimer 1994 ; nelson et al .
1998 ; pickett et al . |
4,435 | Suppose that you have an abstract for a scientific paper: models of a rotating universe have been studied widely since gdel @xcite , who showed an example that is consistent with general relativity ( gr ) . by now , the possibility of a rotating universe has been discussed comprehensively in the framework of some types of bianchi s models , such as type v , vii and ix @xcite , and different approaches have been proposed to constrain the rotation .
recent discoveries of some non - gaussian properties of the cosmic microwave background anisotropies ( cmba ) @xcite , such as the suppression of the quadrupole and the alignment of some multipoles draw attention to some bianchi models with rotation @xcite .
however , cosmological data , such as those of the cmba , strongly prefer a homogeneous and isotropic model .
therefore , it is of interest to discuss the rotation of the universe as a perturbation of the robertson - walker metric , to constrain the rotating speed by cosmological data and to discuss whether it could be the origin of the non - gaussian properties of the cmba mentioned above . here
, we derive the general form of the metric ( up to 2nd - order perturbations ) which is compatible with the rotation perturbation in a flat @xmath0-cdm universe . by comparing the 2nd - order sachs - wolfe effect @xcite due to rotation with the cmba data , we constrain the angular speed of the rotation to be less than @xmath1 rad yr@xmath2 at the last scattering surface .
this provides the first constraint on the shear - free rotation of a @xmath0cdm universe . .
And you have already written the first three sentences of the full article: in contrast to most astronomical objects ( such as planets , stars and galaxies ) , the universe as a whole is usually considered to be non - rotational . however , the possibility that the universe rotates should not be ignored , since solutions of gr corresponding to a rotating universe have been found @xcite indicating that a global rotation is physically allowed .
although it is widely assumed that galaxies align randomly and have zero net angular momentum , there have been many investigations on the general alignment of galaxies .
some even claim that a weak alignment of galaxies does exist@xcite ..
Please generate the next two sentences of the article | such an alignment may be used to explain@xcite the recently discovered non - gaussian properties@xcite of the cmba .
furthermore , jaffe et al . |
4,436 | Suppose that you have an abstract for a scientific paper: in an attempt to quantitatively characterize the recently observed slow dynamics in the isotropic and nematic phase of liquid crystals , we investigate the single - particle orientational dynamics of rodlike molecules across the isotropic - nematic transition in computer simulations of a family of model systems of thermotropic liquid crystals .
several remarkable features of glassy dynamics are on display including non - exponential relaxation , dynamical heterogeneity , and non - arrhenius temperature dependence of the orientational relaxation time . in order to obtain a _ quantitative _ measure of glassy dynamics in line with the estbalished methods in supercooled liquids ,
we construct a relaxation time versus scaled inverse temperature plot , and demonstrate that one can indeed define a fragility index for thermotropic liquid crystals , that depends on density and aspect ratio .
the values of the fragility parameter are surprisingly in the range one observed for glass forming liquids .
a plausible correlation between the energy landscape features and the observed fragility is discussed . .
And you have already written the first three sentences of the full article: thermotropic liquid crystals exhibit exotic phase behavior upon temperature variation .
the nematic phase is rich with a long - ranged orientational order but lacks translational order . the isotropic - nematic (
i - n ) phase transition , which is believed to be weakly first order in nature with certain characteristics of the continuous transition , has been a subject of immense attention in condensed matter physics and material sciences @xcite ..
Please generate the next two sentences of the article | in contrast , the dynamics of thermotropic liquid crystals have been much less studied , the focus being mostly on the long - time behavior of orientational relaxation near the i - n transition @xcite . a series of optical kerr effect ( oke ) measurements have , however , recently studied collective orientational relaxation in the isotropic phase near the i - n transition over a wide range of time scales @xcite .
the dynamics have been found to be surprisingly rich , the most intriguing feature being the power law decay of the oke signal at short - to - intermediate times @xcite . |
4,437 | Suppose that you have an abstract for a scientific paper: the damage growth and surface modifications in si(100 ) , induced by 25 kev si@xmath0 cluster ions , as a function of fluence , @xmath1 , has been studied using atomic force microscopy ( afm ) and channeling rutherford backscattering spectrometry ( crbs ) .
crbs results indicate a nonlinear growth in damage from which it has been possible to get a threshold fluence , @xmath2 , for amorphisation as @xmath3 ions @xmath4 . for @xmath1 below @xmath2 , a growth in damage as well as surface roughness has been observed . at a @xmath1 of @xmath5 ions @xmath4 , damage saturation coupled with a much reduced surface roughness has been found . in this case
a power spectrum analysis of afm data showed a significant drop , in spectral density , as compared to the same obtained for a fluence , @xmath6 .
this drop , together with damage saturation , can be correlated with a transition to a stress relaxed amorphous phase .
irradiation with similar mass cs@xmath7 ions , at the same energy and fluence , has been found to result in a reduced accumulation of defects in the near surface region leading to reduced surface features . .
And you have already written the first three sentences of the full article: cluster ion implantation can be regarded as a forerunner technology as compared to the conventional ion implantation technique used to dope sub - micron devices @xcite . using cluster ions very shallow implantation
can be achieved at very low energy . however , with cluster implantation , nonlinear effects arising in the energy loss processes , as a result of the correlated motion of the constituent atoms , play an important role in deciding the defect structure near the target surface .
in addition to resulting in a nonlinear growth in subsurface damage , cluster ion impact , through sputtering , can also results in kinetic roughening and smoothening of the surface exposed @xcite . in view of all this.
Please generate the next two sentences of the article | , there has been a lot of activities involving low energy cluster ion irradiation related to nonlinear sputtering @xcite , nonlinear damage and defect production @xcite , along with the formation of various kind of surface features @xcite . in connection with the above ,
si , presents itself as a very important material where low energy cluster ions can be used for shallow implantation , of interest to technology . in some earlier work , |
4,438 | Suppose that you have an abstract for a scientific paper: let @xmath0 be a closed , connected subgroup of a connected , simple lie group @xmath1 with finite center .
the homogeneous space @xmath2 has a _ tessellation _ if there is a discrete subgroup @xmath3 of @xmath1 , such that @xmath3 acts properly discontinuously on @xmath2 , and the double - coset space @xmath4 is compact .
note that if either @xmath0 or @xmath2 is compact , then @xmath2 has a tessellation ; these are the obvious examples .
it is not difficult to see that if @xmath1 has real rank one , then only the obvious homogeneous spaces have tessellations .
thus , the first interesting case is when @xmath1 has real rank two .
in particular , r. kulkarni and t. kobayashi constructed examples that are not obvious when @xmath5 or @xmath6 . h. oh and d. witte constructed additional examples in both of these cases , and obtained a complete classification when @xmath7 .
we simplify the work of oh - witte , and extend it to obtain a complete classification when @xmath8 .
this includes the construction of another family of examples .
the main results are obtained from methods of y. benoist and t. kobayashi : we fix a cartan decomposition @xmath9 , and study the intersection @xmath10 .
our exposition generally assumes only the standard theory of connected lie groups , although basic properties of real algebraic groups are sometimes also employed ; the specialized techniques that we use are developed from a fairly elementary level .
# 1 latex@info#1 font@info#1 .
And you have already written the first three sentences of the full article: [ pddefn ] a group @xmath3 of homeomorphisms of a topological space @xmath11 acts _ properly discontinuously _ on @xmath11 if , for every compact subset @xmath12 of @xmath11 , @xmath13 classically , a discrete group @xmath3 of isometries of a riemannian manifold @xmath11 is a crystallographic group if @xmath3 acts properly discontinuously on @xmath11 , and the quotient @xmath14 is compact .
the @xmath3-translates of any fundamental domain for @xmath14 form a tessellation of @xmath11 .
these notions generalize to any homogeneous space , even without an invariant metric ..
Please generate the next two sentences of the article | [ tessdefn ] let * @xmath1 be a lie group and * @xmath0 be a closed subgroup of @xmath1
. a discrete subgroup @xmath3 of @xmath1 is a _ crystallographic group _ for @xmath2 if 1 . |
4,439 | Suppose that you have an abstract for a scientific paper: let @xmath0 be the dehn twist about a circle @xmath1 on an orientable surface .
it is well known that for each circle @xmath2 and an integer @xmath3 , @xmath4 , where @xmath5 is the geometric intersection number .
we prove a similar formula for circles on nonorientable surfaces . as a corollary
we prove some algebraic properties of twists on nonorientable surfaces .
we also prove that if @xmath6 is the mapping class group of a nonorientable surface @xmath7 , then up to a finite number of exceptions , the centraliser of the subgroup of @xmath6 generated by the twists is equal to the centre of @xmath6 and is generated by twists about circles isotopic to boundary components of @xmath7 . .
And you have already written the first three sentences of the full article: let @xmath8 be a smooth , nonorientable , compact surface of genus @xmath9 with @xmath10 boundary components and @xmath11 punctures . if @xmath10 and/or @xmath11 is zero then we omit it from the notation . if we do not want to emphasise the numbers @xmath12 , we simply write @xmath7 for a surface @xmath8 . recall that @xmath13 is a connected sum of @xmath9 projective planes and @xmath8 is obtained from @xmath14 by removing @xmath10 open disks and specifying a set @xmath15 of @xmath11 distinguished points in the interior of @xmath7 .
let @xmath16 be the group of all diffeomorphisms @xmath17 such that @xmath18 is the identity on each boundary component and @xmath19 .
by @xmath20 we denote the quotient group of @xmath16 by the subgroup consisting of the maps isotopic to the identity , where we assume that the isotopies fix @xmath15 and are the identity on each boundary component ..
Please generate the next two sentences of the article | @xmath20 is called the _ mapping class group _ of @xmath7 .
the mapping class group of an orientable surface is defined analogously , but we consider only orientation preserving maps . |
4,440 | Suppose that you have an abstract for a scientific paper: _ chandra _ images of the elliptical galaxy ngc 4261 have revealed an anisotropy in the spatial distribution of the off - nuclear x - ray sources , interpreted by zezas et al .
as evidence of an association with a young stellar population .
our independent analysis of archive x - ray ( _ chandra _ ) and optical ( int and _ hst _ ) observations confirms the anisotropy of the x - ray sources but conducts to a different interpretation for their origin .
we find that nearly half of the x - ray sources are associated to a globular cluster ( optical counterpart ) suggesting that they are accreting low - mass x - ray binaries .
where color index information is available , the x - ray sources are found to reside in red ( metal - rich ) systems .
the luminosity function of the x - ray sources is also consistent with the one drawn from a population of low mass x - ray binaries .
we further investigate the properties of the sample of point - like sources obtained from archival optical images that we suggest are good globular cluster candidates and for which we find that the projected spatial distribution is non - homogeneous .
in addition , we show that the distributions of the optical and x - ray populations are very similar , which leads us to conclude that the spatial anisotropy of the x - ray sources in ngc 4261 is mostly a reflection of the anisotropy of the globular cluster population . .
And you have already written the first three sentences of the full article: ngc 4261 is an early - type galaxy in the virgo west cloud , at the distance of 32 mpc ( @xcite ) .
it belongs to a group of galaxies ( @xcite ) that does not show prominent sign of gravitational interactions .
the h - band luminosity of ngc 4261 is @xmath0 corresponding to a dynamical mass of @xmath1 ( using a mass to light ratio of about 1.2 , from @xcite ) , ranking this galaxy among the most massive galaxies in virgo ..
Please generate the next two sentences of the article | the optical spectrum is consistent with a dominant population of old stars ( @xmath2 gyr , @xcite ) and the light distribution is smooth with no evidence of sub - structure ( @xcite ; @xcite ) .
ngc 4261 is a fri radio galaxy ( 3c 270 ) showing two radio jets emanating from a nucleus hosting a supermassive black hole with a mass of about 5 @xmath3 10@xmath4 m@xmath5 ( @xcite ) surrounded by a dusty torus and a nuclear disk ( @xcite ; @xcite ) . |
4,441 | Suppose that you have an abstract for a scientific paper: we report the discovery of supersonic downflows in a sunspot light bridge using measurements taken with the spectropolarimeter on board the _ hinode _ satellite .
the downflows occur in small patches close to regions where the vector magnetic field changes orientation rapidly , and are associated with anomalous circular polarization profiles .
an inversion of the observed stokes spectra reveals velocities of up to 10 km s@xmath0 , making them the strongest photospheric flows ever measured in light bridges .
some ( but not all ) of the downflowing patches are cospatial and cotemporal with brightness enhancements in chromospheric h filtergrams .
we suggest that these flows are due to magnetic reconnection in the upper photosphere / lower chromosphere , although other mechanisms can not be ruled out . .
And you have already written the first three sentences of the full article: light bridges ( lbs ) are bright structures in the otherwise dark umbra that often exhibit a granular - like morphology @xcite .
they represent a discontinuity or interruption in the regular umbral field @xcite .
lbs are known to harbor weak and inclined fields @xcite , but their origin and magnetic nature is still a matter of debate @xcite ..
Please generate the next two sentences of the article | one of the reasons that make lbs interesting is their chromospheric activity , seen as surges in h@xmath1 @xcite , localized brightenings in h filtergrams @xcite , and brightness enhancements in the upper chromosphere and transition region @xcite .
the stressed magnetic configuration associated with lbs is perceived to be responsible for this activity , but the precise relationship , if any , is yet to be established . |
4,442 | Suppose that you have an abstract for a scientific paper: electron density diagnostics based on a line intensity ratio of si x are applied to the x - ray spectra of procyon , @xmath0 cen a@xmath1b , capella and @xmath2 eri measured with the low energy transmission grating spectrometer ( letgs ) combined with high - resolution camera ( hrc ) on board the _ chandra x - ray observatory_. the ratio @xmath3 of the intensities of the si x lines at 50.524 and 50.691 is adopted .
a certain of the temperature effect in @xmath3 appears near the low - density limit region , which is due to the contamination of si x line at 50.703 . using the emission measure distribution ( emd ) model derived by audard et al .
( 2001 ) for capella and emissivities calculated with apec model by smith et al .
( 2001 ) , we successfully estimate contributions of fe xvi lines at 50.367 and 50.576 ( 73% and 62% , respectively ) . a comparison between observed ratios and theoretical predictions constrains the electron densities ( in logarithmic ) for procyon to be 8.61@xmath4 @xmath5 , while for @xmath0
cen a@xmath1b , capella and @xmath2 eri to be 8.81@xmath6 @xmath5 , 8.60@xmath7 @xmath5 , 9.30@xmath8 @xmath5 and 9.11@xmath9 @xmath5 , respectively .
the comparison of our results with those constrained by the triplet of he - like carbon shows a good agreement . for normal stars ,
our results display a narrow uncertainty , while for active stars , a relatively larger uncertainty , due to the contamination from fe xvi lines , is found .
another possible reason may be that the determination of the continuum level , since the emission lines of si x become weak for the active stars . for @xmath2 eri , an electron density in the c v forming region
was estimated firstly through si x emissions . .
And you have already written the first three sentences of the full article: since the seminal work by vaiana et al .
( 1981 ) , it has become clear that all late - type stars share the same basic coronal characteristics : hot thermal plasma with temperatures around 110 mk covering stellar surfaces , magnetic confinement , the presence of flares , etc .
a systemic investigation indicates that most active stars have x - ray luminosity up to 2 orders of magnitude higher than that of solar corona ( scelsi et al ..
Please generate the next two sentences of the article | 2005 ; peres et al . 2004 ) .
present popular assumption for interpretation of such difference can be attributed to their different composition in terms of various kinds of coronal structures ( ranging from the relatively faint and cool structures of the background corona to the very bright and hot flaring regions ) and to the number of x - ray emitting coronal structures present . |
4,443 | Suppose that you have an abstract for a scientific paper: we review recent applications of equivariant dimensional reduction techniques to the construction of yang - mills - higgs - dirac theories with dynamical mass generation and exactly massless chiral fermions .
( based on invited talk given by the first author at the 2nd school on `` quantum gravity and quantum geometry '' session of the 9th hellenic school on elementary particle physics and gravity , corfu , greece , september 1320 2009 . to be published in _ general relativity and gravitation_. ) .
And you have already written the first three sentences of the full article: the idea that the observed fundamental forces in 4-dimensions can be understood in terms of the dynamics of a simpler higher dimensional theory is now nearly 90 years old @xcite .
starting from a 5-dimensional theory on a manifold @xmath0 , where @xmath1 is a curved 4-dimensional space - time and the fifth dimension is a perfect circle with radius @xmath2 , and taking the 5-dimensional line element to be @xmath3 : @xmath4 where @xmath5 is a 4-dimensional vector potential , the 5-dimensional einstein action reduces to @xmath6 where @xmath7 is a @xmath8 field strength in 4-dimensions and @xmath9 . if we now introduce extra matter , e.g. a scalar field @xmath10 , and perform a harmonic expansion on @xmath11 , @xmath12 then the 5-dimensional kinetic term for @xmath10 gives rise to an infinite tower of massive fields in @xmath1 , @xmath13 , with masses @xmath14 .
a non - abelian generalisation of the kaluza - klein idea uses a @xmath15-dimensional manifold @xmath16 , with @xmath17 compact lie groups ..
Please generate the next two sentences of the article | the co - set space @xmath18 has isometry group @xmath19 and holonomy group @xmath20 . performing the integral @xmath21 over the internal space , with @xmath22 the @xmath19-invariant measure on @xmath18 , leads to yang - mills gauge theory in 4-dimensions with gauge group @xmath19
; e.g. @xmath23 , with @xmath24 isometry and @xmath8 holonomy , gives 4-dimensional einstein - yang - mills theory with gauge group @xmath24 , see e.g. @xcite . |
4,444 | Suppose that you have an abstract for a scientific paper: the @xmath0-ray binary ls i + 61 303 is one of the brightest fermi sources , with orbitally modulated emission across the electromagnetic spectrum .
here we present h@xmath1 spectra of ls i + 61 303 that exhibit a dramatic emission burst shortly before apastron , observed as a redshifted shoulder in the line profile . a correlated burst in radio , x - ray , and gev emission
is observed at the same orbital phase .
we interpret the source of the emission as a compact pulsar wind nebula that forms when a tidal mass stream from the be circumstellar disk interacts with the relativistic pulsar wind .
the h@xmath1 emission offers an important probe of the high energy emission morphology in this system . .
And you have already written the first three sentences of the full article: ls i + 61 303 is a high mass x - ray binary ( hmxb ) that consists of an optical star with spectral type b0 ve and an unknown compact companion in a highly eccentric , 26.5 day orbit @xcite . while the system has a relatively low x - ray luminosity for a hmxb , ls i + 61 303 is the 15th brightest @xmath0-ray source included in the _ fermi _ lat 1-year point source catalogue ( @xcite ) . the be disk interacts with the compact companion , producing emission that has been observed to vary with orbital phase at every wavelength across the electromagnetic spectrum , from radio to tev ( eg . @xcite , @xcite ) .
@xcite found periodic radio outbursts that peak near @xmath2 , and they defined the arbitrary reference for zero phase at hjd 2,443,366.775 that remains the conventional definition for ls i + 61 303 .
periastron occurs at @xmath3 @xcite ..
Please generate the next two sentences of the article | during 2008 october and november , we performed an intense multiwavelength observing campaign on ls i + 61 303 supported by a _
cycle 1 program . |
4,445 | Suppose that you have an abstract for a scientific paper: we study a class of models with long - range repulsive interactions of the generalized coulomb form @xmath0 .
we show that decreasing the interaction exponent in the regime @xmath1 dramatically depresses the charge ordering temperature @xmath2 in any dimension @xmath3 , reflecting the strong geometric frustration produced by long - range interactions .
a nearly frozen coulomb liquid then survives in a broad pseudogap phase found at @xmath4 , which is characterized by an unusual temperature dependence of all quantities .
in contrast , the leading critical behavior very close to the charge - ordering temperature remains identical as in models with short - range interactions .
pseudogap , coulomb , universality class , edmft .
And you have already written the first three sentences of the full article: the phenomenon of screening has long been known in presence of long - range coulomb interactions , and it is generally expected to render the observed behavior very similar to that of systems with short - range interactions . indeed , recent computational work has investigated the critical behavior close to charge ordering in lattice coulomb systems @xcite , suggesting the ising universality class .
in addition , analytical arguments have been presented @xcite supporting this view , for a broad class of lattice models with the generalized coulomb interaction of the form @xmath5 in @xmath3 dimensions .
we should mention , however , that long - range interactions are generally expected to produce mean - field like critical behavior for @xmath6 , while for @xmath7 one expect short - range critical behavior ..
Please generate the next two sentences of the article | the nontrivial effect of long - range interactions upon the critical behavior is possible only for @xmath8 , because in this regime the interaction is `` integrable '' ( no neutralizing background is needed ) , and screening becomes inoperative .
should one expect any interesting or novel physics in coulomb - like models ( @xmath1 ) , in comparison to the short - range situation ? |
4,446 | Suppose that you have an abstract for a scientific paper: in this article , the three point qcd sum rules is used to compute the strong coupling constants of vertices containing the strange bottomed ( charmed ) mesons with pion .
the coupling constants are calculated , when both the bottom ( charm ) and pion states are off - shell .
a comparison of the obtained results of coupling constants with the existing predictions is also made .
key words : strong coupling constant , meson , qcd sum rules , bottom , charm . .
And you have already written the first three sentences of the full article: during last ten years , there have been numerous published research articles devoted to the precise determination of the strong form factors and coupling constants of meson vertices via qcd sum rules ( qcdsr ) @xcite .
qcdsr formalism have also been successfully used to study some of the `` exotic '' mesons made of quark- gluon hybrid ( @xmath0 ) , tetraquark states ( @xmath1 ) , molecular states of two ordinary mesons , glueballs and many others @xcite .
coupling constants can provide a real possibility for studying the nature of the bottomed and charmed pseudoscalar and axial vector mesons ..
Please generate the next two sentences of the article | more accurate determination of these coupling constants play an important role in understanding of the final states interactions in the hadronic decays of the heavy mesons .
our knowledge of the form factors in hadronic vertices is of crucial importance to estimate hadronic amplitudes when hadronic degrees of freedom are used . when all of the particles in a hadronic vertex are on mass - shell , the effective fields of the hadrons describe point - like physics . |
4,447 | Suppose that you have an abstract for a scientific paper: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _....
And you have already written the first three sentences of the full article: argumentation frameworks ( afs ) are a convenient way to represent conflicting information and to deduce which subset of the information can be inferred .
for instance , they can be used to model dialogs between several agents @xcite or to analyze on - line discussion between social network users @xcite .
argumentation can also be useful in a mono - agent setting , for instance to infer non - trivial conclusions from an inconsistent knowledge base @xcite ..
Please generate the next two sentences of the article | the domain called _ dynamics of argumentation _ has become a hot topic in recent years , with numerous publications about it .
the first ones consider really classical debate scenarios as the source of the dynamic process @xcite . |
4,448 | Suppose that you have an abstract for a scientific paper: generating nonclassical states of photons such as polarization entangled states on a monolithic chip is a crucial step towards practical applications of optical quantum information processing such as quantum computing and quantum key distribution .
here we demonstrate two polarization entangled photon sources in a single monolithic semiconductor waveguide .
the first source is achieved through the concurrent utilization of two spontaneous parametric down - conversion ( spdc ) processes , namely type-0 and type - i spdc processes .
the chip can also generate polarization entangled photons via the type - ii spdc process , enabling the generation of both co - polarized and cross - polarized entangled photons in the same device . in both cases , polarization entanglement is generated directly on the chip without the use of any off - chip compensation , interferometry or bandpass filtering .
this enables direct , chip - based generation of both bell states @xmath0 and @xmath1 simultaneously utilizing the same pump source .
in addition , based on compound semiconductors , this chip can be directly integrated with it own pump laser .
this technique ushers an era of self - contained , integrated , electrically pumped , room - temperature polarization entangled photon sources . .
And you have already written the first three sentences of the full article: entangled photons are essential building blocks for optical quantum information processing , such as quantum computing ( qc ) @xcite and quantum key distribution ( qkd ) @xcite .
conventionally , entangled photons have been generated using a myriad of techniques , most notably by using the process of spontaneous parametric down - conversion ( spdc ) utilizing second order nonlinearities in crystals @xcite .
properties such as brightness , scalability , compact form - factor and room temperature operation play key roles in enabling us to fully profit from entangled photon sources in applications such as qc and qkd . as such , the physics and technology of generating and manipulating entangled photons in monolithic settings have recently been topics of immense interest ..
Please generate the next two sentences of the article | harnessing such effects in a monolithic form - factor also enables further incorporation of other photonic components that may be necessary for the aforementioned applications @xcite .
this provided the drive that motivated the early work on implementing entangled sources in waveguides of crystals with appreciable second order nonlinearities such as lithium niobate @xcite . realizing entangled photon sources in monolithic settings enables much more than the inclusion of numerous necessary components simultaneously |
4,449 | Suppose that you have an abstract for a scientific paper: we present the results of high resolution sph simulations of the evolution of gravitationally unstable protoplanetary disks .
we report on calculations in which the disk is evolved using a locally isothermal or adiabatic equation of state ( with shock heating ) , and also on new simulations in which cooling and heating by radiation are explicitly modeled .
we find that disks with a minimum toomre parameter @xmath0 fragment into several gravitationally bound protoplanets with masses from below to a few jupiter masses .
this is confirmed also in runs where the disk is given a quiet start , growing gradually in mass over several orbital times .
a cooling time comparable to the orbital time is needed to achieve fragmentation , for disk masses in the range @xmath1 .
after about 30 orbital times , merging between the bound condensations always leads to 2 - 3 protoplanets on quite eccentric orbits .
# 1_#1 _ # 1_#1 _ = @scaling.95 # 1@scaling#1 # 1=@scaling the formation of gas giants as a result of fragmentation in a protoplanetary disk , an old idea ( kuiper 1951 , cameron 1978 ) , has been recently revived by a number of studies that are finally laying the ground for a quantitative understanding of such process ( boss 2001 , 2002 ; mayer et al .
2002 , 2003;pickett et al . 2000 , 2003 ) .
the renewed consideration of this mechanism stems from several problems faced by the conventional model of giant planet formation , in which first a rocky core is assembled over @xmath2 years and then a gaseous envelope is accreted in a few million years or more , the exact timescale being dependent on the details of the models like the disk surface density and the opacity of the mixture of gas and dust ( lissauer 1993 ) .
these timescales are an order of magnitude too long to form planets before the disk is dissipated by photoevaporation in highly irradiated environments like the orion nebula ( throop et al .
2001 ) , and are a bit too tight even when compared to the typical lifetime of disks in more....
And you have already written the first three sentences of the full article: the 3d disk models initially extend between 4 and 20 au .
the central star is modeled as a softened point mass with a mass of @xmath5 .
there are no fixed boundaries ; the disk is free to expand and contract and both the central star and the disk can respond to their mutual gravitational field ..
Please generate the next two sentences of the article | the disk surface density profile is of the type @xmath6 .
disk models have masses between @xmath7 and @xmath8 and initial temperature profiles as those used in ma02 . |
4,450 | Suppose that you have an abstract for a scientific paper: we present numerical simulations of the axisymmetric accretion of a massive magnetized plasma torus on a rotating black hole .
we use a realistic equation of state , which takes into account neutrino cooling and energy loss due to nucleus dissociations .
we simulated various magnetic field configurations and torus models , both optically thick and thin for neutrinos .
it is shown that the neutrino cooling does not significantly change either the structure of the accretion flow or the total energy release of the system .
the calculations evidence heating of the wind surrounding the collapsar by the shock waves generated at the jet - wind border .
this mechanism can give rise to a hot corona around the binary system like ss433 .
angular momentum of the accreting matter defines the time scale of the accretion . due to the absence of the magnetic dynamo in our calculations ,
the initial strength and topology of the magnetic field determines magnetization of the black hole , jet formation properties and the total energy yield .
we estimated the total energy transformed to jets as @xmath0 ergs which was sufficient to explain hypernova explosions like grb 980425 or grb 030329 .
gamma - rays : bursts , methods : numerical , ( magnetohydrodynamics ) mhd , black hole physics . .
And you have already written the first three sentences of the full article: in spite of significant progress in recent years , the nature of gamma - ray bursts ( grb ) , discovered by @xcite more than 30 years ago , is still enigmatic .
although the light curves and emission spectra of grbs are very diverse , they seem to split into two groups of possibly different origin : long bursts ( @xmath1 s ) with a softer spectrum and short bursts ( @xmath2 s ) with a harder spectrum @xcite .
the long grbs are often believed to be associated with star - formation regions @xcite ..
Please generate the next two sentences of the article | only these regions can host massive stars that have astronomically very short lifetime and die soon after the birth .
in fact , recent observations have provided strong arguments in favour of the connection of grbs with the deaths of massive stars . |
4,451 | Suppose that you have an abstract for a scientific paper: we treat continuum electrodynamics as an axiomatic formal theory based on the macroscopic maxwell
minkowski equations applied to a thermodynamically closed system consisting of an antireflection - coated block of a simple linear dielectric material situated in free - space that is illuminated by a quasimonochromatic field .
we prove that valid theorems of the formal theory of maxwellian continuum electrodynamics are inconsistent with energy
momentum conservation laws for the unimpeded , inviscid , incompressible flow of non - interacting particles , photons , in the continuum limit .
we also show that valid theorems of maxwellian continuum electrodynamics are contradicted by the index - independent lorentz factor of von laue s application of the einstein theory of special relativity to a dielectric .
therefore , the extant theoretical treatments of macroscopic electrodynamics , special relativity , and energy momentum conservation must be regarded as being mutually inconsistent in a region of space in which the effective speed of light is @xmath0 .
having proven the existing theories to be inconsistent , it is customary to propose alternatives .
we derive , from first principles , a self - consistent alternative theoretical treatment of electrodynamics , special relativity , and energy momentum conservation in an isotropic , homogeneous , linear dielectric - filled , flat , non - minkowski , continuous material spacetime .
there is sufficient commonality with the classic theories that the extensive theoretical and experimental work that is correctly described by maxwellian continuum electrodynamics , conservation , and von laue
einstein dielectric special relativity has an equivalent formulation in the new theory .
the more complex issues of the abraham minkowski momentum controversy and rosen s refractive index - dependent dielectric special relativity theory have robust resolutions in the new theory .
0.5 cm keywords : abraham minkowski controversy , energy momentum tensor ,....
And you have already written the first three sentences of the full article: the seminal experiments on electricity and magnetism in the @xmath1@xmath2 centuries were codified into a set of physical laws , gauss s law , ampre s law , faraday s law , and thompson s law , that form the foundation of early classical electromagnetism .
in the course of time , a crisis emerged when it was determined that ampre s law is not consistent with the continuity equation for charge and current . in 1865 , maxwell @xcite proposed a modification to ampre s law that resolved the inconsistency and established a new paradigm for electrodynamics that led to the prediction of electromagnetic wave phenomena . over two decades later , hertz @xcite demonstrated the existence of electromagnetic waves , providing experimental validation for the maxwell theory . with the replacement of ampre s law by the maxwell ampre law , the collective laws of classical electrodynamics are known as maxwell s equations , appearing in a microscopic formulation that applies to microscopic fields in the vacuum and in a macroscopic formulation as equations of motion for averaged fields in continuous media .
the maxwell equations for the components of the fields were recast as vector equations by heaviside and by minkowski . the maxwell .
Please generate the next two sentences of the article | minkowski equations are the dominant paradigms of microscopic classical electrodynamics and of macroscopic classical continuum electrodynamics . for over fifteen decades ,
maxwellian continuum electrodynamics has been extraordinarily successful in predicting and describing real - world phenomena that occur in dielectric materials . |
4,452 | Suppose that you have an abstract for a scientific paper: giant pulses ( gps ) , occasional individual pulses with an intensity 100 times the average intensity , have been detected in four pulsars todate .
their origin is not well understood , but studies suggest a connection between the strength of magnetic field at the light cylinder @xmath0 and the existence of gps . here , we report on detection of significant large amplitude pulses ( laps ) in two more pulsars with high values of @xmath0 , psrs j0218 + 4232 and b1957 + 20 , observed using giant meterwave radio telescope ( gmrt ) .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: giant pulses ( gps ) have been reported in four pulsars ( b0531 + 21 , b1937 + 21 , b1821@xmath124 and b0540@xmath169 ) todate ( staelin & reifenstein 1968 ; lundgren et al . 1995 ; cognard et al .
1996 ; romani & johnston 2001 ; johnston & romani 2003 ) .
three of these pulsars are millisecond pulsars ( msps ) and also show strongly pulsed hard x - ray profiles ( takahashi et al ..
Please generate the next two sentences of the article | the radio gps occur in a narrow phase window close to the high energy non - thermal pulse indicating a common magnetospheric origin .
all these pulsars have a high value of @xmath0 . |
4,453 | Suppose that you have an abstract for a scientific paper: we use halo effective field theory to analyze the universal features of proton halo nuclei bound due to a large s - wave scattering length . with a lagrangian built from effective core and valence - proton fields ,
we derive a leading - order expression for the charge form factor . within the same framework we also calculate the radiative proton capture cross section .
our general results at leading order are applied to study the excited @xmath0 state of fluorine-17 , and we give results for the charge radius and the astrophysical s - factor .
halo nuclei , charge radius , radiative capture , effective field theory .
And you have already written the first three sentences of the full article: exotic isotopes along the neutron and proton drip lines are important for our understanding of the formation of elements and they constitute tests of our understanding of nuclear structure .
the proton- and neutron - rich regimes in the chart of nuclei are therefore the focus of existing and forthcoming experimental facilities around the world @xcite .
the emergence of new degrees of freedom is one important feature of these systems ; exemplified , e.g. , by the discovery of several nuclear halo states along the drip lines @xcite ..
Please generate the next two sentences of the article | halo states in nuclei are characterized by a tightly bound core with weakly attached valence nucleon(s ) .
universal structures of such states can be considered a consequence of quantum tunneling , where tightly - bound clusters of nucleons behave coherently at low energies and the dynamics is dominated by relative motion at distances beyond the region of the short - range interaction . in the absence of the coulomb interaction , it is known that halo nuclei bound due to a large positive s - wave scattering length will show universal features @xcite . in the case of proton halo nuclei , however , the coulomb interaction introduces an additional momentum scale @xmath1 , which is proportional to the charge of the core and the reduced mass of the halo system . |
4,454 | Suppose that you have an abstract for a scientific paper: in this work , we studied the properties of the spherical indicatrices of involute curve of a space curve and presented some characteristic properties in the cases that involute curve and evolute curve are slant helices and helices , spherical indicatrices are slant helices and helices and we introduced new representations of spherical indicatrices . .
And you have already written the first three sentences of the full article: the specific curve pairs are the most popular subjects in curve and surface theory and involute - evolute pair is one of them .
we can see in most textbooks various applications not only in curve theory but also in surface theory and mechanic . in this study ,
the spherical indicatrices of involute of a space curve are given . in order to make a involute of a space curve and its evolute curve slant helix , the feature that spherical indicatrices curve s need to have.
Please generate the next two sentences of the article | are examined .
let @xmath0 be a curve with @xmath1 , where @xmath2 @xmath3 . |
4,455 | Suppose that you have an abstract for a scientific paper: we analyze archival _ hst_/stis / fuv - mama imaging and spectroscopy of 13 compact star clusters within the circumnuclear starburst region of m83 , the closest such example .
we compare the observed spectra with semi - empirical models , which are based on an empirical library of galactic o and b stars observed with _ iue _ , and with theoretical models , which are based on a new theoretical uv library of hot massive stars computed with wm - basic .
the models were generated with starburst99 for metallicities of @xmath0 and @xmath1 , and for stellar imfs with upper mass limits of 10 , 30 , 50 , and 100m@xmath2 .
we estimate the ages and masses of the clusters from the best fit model spectra , and find that the ages derived from the semi - empirical and theoretical models agree within a factor of 1.2 on average .
a comparison of the spectroscopic age estimates with values derived from _
multi - band photometry shows a similar level of agreement for all but one cluster .
the clusters have a range of ages from about 3 to 20myr , and do not appear to have an age gradient along m83 s starburst . clusters with strong p - cygni profiles have masses of a few@xmath3m@xmath2 , seem to have formed stars more massive than @xmath4m@xmath2 , and are consistent with a kroupa imf from @xmath5m@xmath2 .
field regions in the starburst lack p - cygni profiles and are dominated by b stars . .
And you have already written the first three sentences of the full article: in the context of disk galaxies , a nuclear or circumnuclear ring is a region of large gas surface density and enhanced star formation , located within 2 kpc of the galactic nucleus . @xcite
distinguish between nuclear disks and nuclear rings , by setting the maximum width of the ring to half the ring radius .
the most compact rings ( ultra - compact nuclear rings , ucnrs ) have radii smaller than 200 pc @xcite ..
Please generate the next two sentences of the article | the atlas of images of nuclear rings @xcite is the most complete atlas of galactic nuclear rings to date and includes 101 barred and unbarred disk galaxies with rings .
the dust nuclear rings around elliptical and s0 galaxies constitute a different class of galactic ring with no associated star formation . |
4,456 | Suppose that you have an abstract for a scientific paper: this paper outlines an approach to the approximation of probability density functions by quadratic forms of weighted orthonormal basis functions with positive semi - definite hermitian matrices of unit trace .
such matrices are called stochastic density matrices in order to reflect an analogy with the quantum mechanical density matrices .
the sdm approximation of a pdf satisfies the normalization condition and is nonnegative everywhere in contrast to the truncated gram - charlier and edgeworth expansions . for bases with an algebraic structure , such as the hermite polynomial and fourier bases , the sdm approximation can be chosen so as to satisfy given moment specifications and can be optimized using a quadratic proximity criterion .
we apply the sdm approach to the fokker - planck - kolmogorov pdf dynamics of markov diffusion processes governed by nonlinear stochastic differential equations .
this leads to an ordinary differential equation for the sdm dynamics of the approximating pdf . as an example
, we consider the smoluchowski sde on a multidimensional torus . .
And you have already written the first three sentences of the full article: practical solvability of performance analysis and control design problems for stochastic systems often depends on tractability of relevant quantities , such as moments of the system variables . for example , the kalman filtering and linear quadratic gaussian control theories @xcite substantially employ the preservation of gaussian nature of probability distributions of the state variables governed by linear sdes . under the linear dynamics , the first and second order moments of the variables ( and more complicated functionals of gaussian distributions )
are amenable to a complete analysis .
it is the convenience of linear gaussian models that makes them so popular in filtering / control with quadratic and related ( for example , risk - sensitive ) performance criteria ..
Please generate the next two sentences of the article | these advantages motivate the approximation of a nonlinear stochastic system by an effective linear model which underlies the stochastic linearization techniques .
the latter date back to @xcite and have recently been extended to quantum stochastic systems @xcite . |
4,457 | Suppose that you have an abstract for a scientific paper: we report on 25 sub - arcsecond binaries , detected for the first time by means of lunar occultations in the near - infrared as part of a long - term program using the isaac instrument at the eso very large telescope .
the primaries have magnitudes in the range k=3.8 to 10.4 , and the companions in the range k=6.4 to 12.1 .
the magnitude differences have a median value of 2.8 , with the largest being 5.4 .
the projected separations are in the range 6 to 748 milliarcseconds and with a median of 18 milliarcseconds , or about 3 times less than the diffraction limit of the telescope . among our binary detections
are a pre - main sequence star and an enigmatic mira - like variable previously suspected to have a companion .
additionally , we quote an accurate first - time near - ir detection of a previously known wider binary .
we discuss our findings on an individual basis as far as made possible by the available literature , and we examine them from a statistical point of view .
we derive a typical frequency of binarity among field stars of @xmath0% , in the resolution and sensitivity range afforded by the technique ( @xmath1 to @xmath2 , and k@xmath3mag , respectively ) .
this is in line with previous results by the same technique but we point out interesting differences that we can trace up to sensitivity , time sampling , and average distance of the targets .
finally , we discuss the prospects for further follow - up studies . .
And you have already written the first three sentences of the full article: lunar occultations ( los ) can efficiently yield high angular resolution observations from the analysis of the diffraction light curves generated when background sources are covered by the lunar limb .
the technique has been employed to measure hundreds of stellar angular diameters , binary stars , and sources with extended circumstellar emission ( see charm2 catalog , * ? ? ?
in the past few years , a program to observe los in the near - infrared at the eso very large telescope ( vlt ) has been very successful both in quantity , with over a thousand events recorded , and in quality with a combination of angular resolution far exceeding the diffraction limit of a single telescope ( @xmath4 ) and a sensitivity significantly better than that currently achieved by long - baseline interferometry ( k @xmath3mag ) ..
Please generate the next two sentences of the article | the drawbacks are that los are fixed - time events , yielding mainly a one - dimensional scan of the source , and that the source can not be chosen at will .
details on the los program at the vlt can be found in @xcite , and references therein . here , we report on 25 sources discovered to be binary with projected separations below one arcsecond , and in fact mostly below the 57 milliarcseconds ( mas ) diffraction limit of the telescope at the given wavelength . |
4,458 | Suppose that you have an abstract for a scientific paper: depending on whether electroweak physics beyond the standard model is based on a linear or on a non - linear implementation of the electroweak symmetry breaking , a linear or a chiral effective lagrangian is more appropriate . in this talk ,
the main low - energy signals that allow to recognize whether the observed `` higgs '' scalar is a dynamical ( composite ) particle or rather an elementary one are presented , in a model - independent way .
the patterns of effective couplings produced upon the assumption of specific composite higgs models are also discussed . .
And you have already written the first three sentences of the full article: the discovery of a light higgs boson at the lhc @xcite completes beautifully the standard model ( sm ) description of fundamental interactions . nonetheless , a number of questions about the theoretical consistency of the theory remain unanswered , and point to the existence of some new physics around or not far from the tev scale . in the lack of direct detection of any new particle , a worthy and rather model - independent tool for the study of beyond - standard model ( bsm ) physics is provided by lorentz and gauge - invariant effective lagrangians , which respect a given set of symmetries , including the low - energy established ones . in particular , with a light higgs observed , two main classes of effective lagrangians are pertinent , depending on how the electroweak ( ew ) symmetry breaking ( ewsb ) is assumed to be realized : linearly for elementary higgs particles or non - linearly for dynamical " -typically composite- ones . in elementary higgs scenarios , the higgs particle belongs to an @xmath0 doublet @xmath1 . if the new physics scale is @xmath2 , where @xmath3 is the ew vacuum expectation value ( vev ) , the corresponding linear effective lagrangian contains operators weighted by inverse powers of the cutoff scale @xmath4 : the leading corrections to the sm lagrangian have then canonical mass dimension @xmath5 @xcite .
a typical example of possible underlying physics are supersymmetric models . in dynamical higgs scenarios , on the other hand ,
the higgs particle is a composite field which happens to be a pseudo - goldstone boson ( gb ) of a global symmetry @xmath6 , that is broken down spontaneously to a subgroup @xmath7 at a scale @xmath8 , corresponding to the masses of the lightest strong resonances ..
Please generate the next two sentences of the article | the higgs mass is protected by the gb shift symmetry , thus avoiding the electroweak hierarchy problem .
explicit realizations include composite higgs models @xcite . |
4,459 | Suppose that you have an abstract for a scientific paper: by combining the 0.12 square degree f814w _ hubble space telescope _ ( _ hst _ ) and _ spitzer _ mips 24 imaging in the first look survey ( fls ) , we investigate the properties of interacting and merging mid - infrared bright and faint sources at @xmath0z@xmath1 .
we find a marginally significant increase in the pair fraction for mips 24 detected , optically selected close pairs , pair fraction@xmath2 at z@xmath31 , in contrast to @xmath4 at @xmath50.4 , while galaxies below our 24 mips detection limit show a pair fraction consistent with zero at all redshifts . additionally , 24 detected galaxies with fluxes @xmath6mjy are on average five times more likely to be in a close galaxy pair between @xmath0z@xmath1 than galaxies below this flux limit . using the 24 flux to derive the total far - ir luminosity we find that paired galaxies ( early stage mergers ) are responsible for @xmath7 of the ir luminosity density resulting from star formation at @xmath8 while morphologically classified ( late stage ) mergers make up @xmath9
this implies that @xmath10 of the infrared luminosity density and in turn @xmath11 of the star formation rate density at @xmath8 can be attributed to galaxies at some stage of a major merger or interaction .
we argue that , close pairs / mergers in a lirg / ulirg phase become increasingly important contributers to the ir luminosity and star formation rate density of the universe at @xmath120.7 . .
And you have already written the first three sentences of the full article: hierarchical models and observations suggest that galaxy mergers and interactions play a key role in galaxy assembly and star formation , but to what extent is still unclear .
studies of gas - rich mergers in the local universe ( e.g. , antennae ; see * ? ? ?
* ) and n - body simulations @xcite have revealed fundamental signatures of the galaxy merger process , including tidal tails , multiple nuclei , and violent bursts of star formation ..
Please generate the next two sentences of the article | while interaction - induced star formation is thought to be primarily responsible for ultra luminous infrared galaxies ( ulirgs , which have @xmath13 ) both locally and at high redshift @xcite , luminous infrared galaxies ( lirgs , @xmath14 ) appear to have multiple driving mechanisms , merger - induced star formation being only one .
luminous infrared ( ir ) galaxies are thought to be the dominant producers of the cosmic infrared background ( cirb ) , and major contributors to the evolution of the cosmic star formation rate ( csfr ) of galaxies , especially at @xmath15 @xcite . |
4,460 | Suppose that you have an abstract for a scientific paper: in a previous paper ( avotina _ et al . _ phys .
rev .
b * 71 * , 115430 ( 2005 ) ) we have shown that in principle it is possible to image the defect positions below a metal surface by means of a scanning tunnelling microscope .
the principle relies on the interference of electron waves scattered on the defects , which give rise to small but measurable conductance fluctuations .
whereas in that work the band structure was assumed to be free - electron like , here we investigate the effects of fermi surface anisotropy .
we demonstrate that the amplitude and period of the conductance oscillations are determined by the local geometry of the fermi surface .
the signal results from those points for which the electron velocity is directed along the vector connecting the point contact to the defect . for a general fermi surface geometry
the position of the maximum amplitude of the conductance oscillations is not found for the tip directly above the defect .
we have determined optimal conditions for determination of defect positions in metals with closed and open fermi surfaces . .
And you have already written the first three sentences of the full article: the interference of electron waves scattered by single defects results in an oscillatory dependence of the point contact conductance @xmath0 on the applied voltage @xmath1 this effect originates from quantum interference between the principal wave that is directly transmitted through the contact and the partial wave that is scattered by the contact and the defect or several defects .
such conductance oscillations have been observed in quantum point contacts @xcite and investigated theoretically in the papers ludoph , namir , avotina2,avotina3 . in our previous paper
@xcite the oscillatory voltage dependence of the conductance of a tunnel point contact in the presence of a single point - like defect has been analyzed theoretically and it has been shown that this dependence can be used for the determination of defect positions below a metal surface by means of a scanning tunnelling microscope ( stm ) . in the model of a spherical fermi surface ( fs ).
Please generate the next two sentences of the article | the amplitude of the conductance oscillations is maximal when the contact is placed directly above the defect .
the oscillatory part of the conductance @xmath2 for this situation is proportional to @xmath3where @xmath4 the depth of the defect and @xmath5 and @xmath6 are the fermi wave vector and effective mass of the electrons @xcite |
4,461 | Suppose that you have an abstract for a scientific paper: in paper i we studied the theory of gravitational microlensing for a planar distribution of point masses . in this second paper , we extend the analysis to a three - dimensional lens distribution .
first we study the lensing properties of three - dimensional lens distributions by considering in detail the critical curves , the caustics , the illumination patterns , and the magnification cross - sections @xmath0 of multiplane configurations with two , three , and four point masses . for @xmath1 point masses that are widely separated in lagrangian space ,
we find that there are @xmath2 critical curves in total , but that only @xmath3 of these produce prominent caustic - induced features at the high magnification end of @xmath0 . in the case of a low optical depth random distribution of point masses , we show that the multiplane lens equation near a point mass can be reduced to the single plane equation of a point mass perturbed by weak shear .
this allows us to calculate the caustic - induced feature in the macroimage magnification distribution @xmath4 as a weighted sum of the semi - analytic feature derived in paper i for a planar lens distribution .
the resulting semi - analytic caustic - induced feature is similar to the feature in the planar case , but it does not have any simple scaling properties , and it is shifted to higher magnification . the semi - analytic distribution is compared to the results of previous numerical simulations for optical depth @xmath5 , and they are in better agreement than a similar comparison in the planar case .
we explain this by estimating the fraction of caustics of individual lenses that merge with those of their neighbors . for @xmath6 ,
the fraction is @xmath7 , much less than the @xmath8 for the planar case .
= cmmib10 scaled 1200 = cmmib10 = cmbsy10 scaled 1200 = cmbsy10 = = = = = = = `` 710b = ' ' 710c = `` 710d = ' ' 710e = `` 710f = ' ' 7110 = `` 7111 = ' ' 7112 = `` 7113 = ' ' 7114 = `` 7115 = ' ' 7116 = `` 7117 = ' ' 7118 = `` 7119 = ' '....
And you have already written the first three sentences of the full article: the gravitational lensing effect of an ensemble of point masses has long been a subject of investigation ( see , e.g. , schneider , ehlers , & falco 1992 for a summary of earlier work ) .
most of the studies have focused on the situation where the spatial distribution of the point mass lenses is `` compact , '' i.e. , the size of the region within which the lenses are distributed is much smaller than the other distances ( those between the source and the lenses and between the observer and the lenses ) in the problem . for gravitational lensing calculations , a compact distribution of lenses
is usually approximated by its projection onto a single lens plane ..
Please generate the next two sentences of the article | the important case of low optical depth , single plane microlensing has been investigated in great detail ( kaiser 1992 ; mao 1992 ; rauch 1992 ; kofman 1996 , hereafter paper i ; see also schneider 1992 and references therein ) , and we now understand reasonably well the caustic structure , the illumination pattern , the probability distribution of macroimage magnification , and the flux variability of macroimages in this case . there are , however , situations in which the lensing objects are modeled by an `` extended '' ( or three - dimensional ) distribution of point masses , i.e. , by a point mass distribution that is comparable in scale to the other distances in the problem .
a well - known example is the microlensing of stars in the large magellanic cloud and the galactic bulge by foreground stars and possibly massive compact halo objects ( machos ) ( alcock 1993 ; aubourg 1993 ; udalski 1993 ) . |
4,462 | Suppose that you have an abstract for a scientific paper: we present submillimetre and mid - infrared imaging observations of five fields centred on quasi - stellar objects ( qsos ) at @xmath0 .
all @xmath1 qsos were detected previously at submillimetre wavelengths . at 850 ( 450 )
@xmath2 m we detect 17 ( 11 ) submillimetre galaxies ( smgs ) in addition to the qsos .
the total area mapped at 850 @xmath2 m is @xmath3 arcmin@xmath4 down to rms noise levels of @xmath5 mjy / beam , depending on the field .
integral number counts are computed from the 850 @xmath2 m data using the same analytical techniques adopted by ` blank - field ' submillimetre surveys .
we find that the ` qso - field ' counts show a clear excess over the blank - field counts at deboosted flux densities of @xmath6 mjy ; at higher flux densities the counts are consistent with the blank - field counts .
robust mid - infrared counterparts are identified for all four submillimetre detected qsos and @xmath7 per cent of the smgs .
the mid - infrared colours of the qsos are similar to those of the local ulirg / agn mrk 231 if placed at @xmath8 whilst most of the smgs have colours very similar to those of the local ulirg arp 220 at @xmath8 .
mid - infrared diagnostics therefore find no strong evidence that the smgs host buried agn although we can not rule out such a possibility .
taken together our results suggest that the qsos sit in regions of the early universe which are undergoing an enhanced level of major star - formation activity , and should evolve to become similarly dense regions containing massive galaxies at the present epoch .
finally , we find evidence that the level of star - formation activity in individual galaxies appears to be lower around the qsos than it is around more powerful radio - loud agn at higher redshifts .
galaxies : formation - galaxies : starburst - galaxies : evolution - galaxies : high redshift - submillimetre - qso : general .
And you have already written the first three sentences of the full article: the popular hierarchical model of galaxy formation predicts that elliptical galaxies found today in the cores of rich clusters formed at high redshifts and at rare high - density peaks of the dark matter distribution . within these regions ,
gas - rich proto - galaxies merge together rapidly , forming stars at a high rate .
the same reservoir of gas used to build the stellar mass can also fuel the growth of the supermassive black holes ( smbh ) found dormant in the centre of the galaxies at low redshift ( e.g. kauffmann & haehnelt 2000 ; page et al ..
Please generate the next two sentences of the article | 2001 ; hopkins et al . 2008 ) . since massive star formation is known to be a dusty phenomenon , the optical light from many young galaxies should be highly obscured .
dust enshrouded star formation is , however , a luminous phenomenon in the millimetre through far - infrared wavebands where the star - light absorbed by dust grains is re - emitted . |
4,463 | Suppose that you have an abstract for a scientific paper: the monogem ring is a bright , diffuse , @xmath0-diameter supernova remnant easily visible in soft x - ray images of the sky .
projected within the ring is a young radio pulsar , psr b0656 + 14 .
an association between the remnant and pulsar has been considered , but was seemingly ruled out by the direction and magnitude of the pulsar proper motion and by a distance estimate that placed the pulsar twice as far from earth as the remnant . here we show that in fact the pulsar was born very close to the center of the expanding remnant , both in distance and projection .
the inferred pulsar and remnant ages are in good agreement .
the conclusion that the pulsar and remnant were born in the same supernova explosion is nearly inescapable .
the remnant distance and age are in remarkable concordance with the predictions of a model for the primary cosmic ray energy spectrum in which the ` knee ' feature is produced by a single dominant source . .
And you have already written the first three sentences of the full article: a bright soft x - ray enhancement in the monoceros and gemini constellations was first detected in rocket experiments over thirty years ago @xcite , and resolved into a shell - like structure by _
heao-2 _ a decade later @xcite .
spectral studies with _ rosat _ confirmed that this so - called ` monogem ring ' is a supernova remnant , probably in the adiabatic expansion phase @xcite ..
Please generate the next two sentences of the article | the distance is poorly constrained by evolutionary arguments self - consistent sedov - taylor models were found by @xcite at all distances between 100 and 1300 pc but distances around 300 pc are preferred on grounds of supernova energetics . at this distance , the model age is 86,000 years , explosion energy is @xmath1 erg , and current radius is 66 pc .
the inferred interstellar medium density is @xmath2 , typical of the hot interstellar medium . |
4,464 | Suppose that you have an abstract for a scientific paper: we have recently described a novel method for the construction of a solid - state optical frequency reference based on doping @xmath0th into high energy band - gap crystals @xcite . since nuclear transitions are far less sensitive to environmental conditions than atomic transitions , we have argued that the @xmath0th optical nuclear transition may be driven inside a host crystal resulting in an optical frequency reference with a short - term stability of @xmath1 at 1 s and a systematic - limited repeatability of @xmath2 .
improvement by @xmath3 of the constraints on the variability of several important fundamental constants also appears possible .
here we present the results of the first phase of these experiments .
specifically , we have evaluated several high energy band - gap crystals ( th : nayf , th : ylf , th : licaf , na@xmath4thf@xmath5 , lisaf ) for their suitability as a crystal host by a combination of electron beam microprobe measurements , rutherford backscattering , and synchrotron excitation / fluorescence measurements .
these measurements have shown licaf to be the most promising host crystal , and using a @xmath6th doped licaf crystal , we have performed a mock run of the actual experiment that will be used to search for the isomeric transition in @xmath0th .
this data indicates that a measurement of the transition energy with a signal to noise ratio ( snr ) greater than 30:1 can be achieved at the lowest expected fluorescence rate . .
And you have already written the first three sentences of the full article: the existence of a low - lying state in @xmath0th , with an estimated natural linewidth , @xmath7 , in the range @xmath8 mhz @xcite , was indirectly established over 3 decades ago @xcite .
however , direct searches for emission from this m1 transition have so far been unsuccessful @xcite .
recently , a new indirect measurement has established that the transition energy is 7.8 @xmath9 0.5 ev @xcite , rather than 3.5 ev as orginally thought ..
Please generate the next two sentences of the article | although well into the vacuum ultraviolet ( vuv ) , this energy is amenable to study by laser spectroscopy , opening the door for use of this transition as a highly stable oscillator in next generation optical clocks . the transition is also predicted to show a 10@xmath10-fold enhancement in sensitivity to the time variation of several fundamental constants@xcite , _
e.g. _ the fine structure constant . while the current measurement uncertainty of the nuclear transition energy is very good by nuclear physics standards , |
4,465 | Suppose that you have an abstract for a scientific paper: the chemical abundances in damped lyman-@xmath0 systems ( dlas ) show more than 2 orders of magnitude variation at a given epoch , possibly because dlas arise in a wide variety of host galaxies .
this could significantly bias estimates of chemical evolution .
we explore the possibility that dlas in which h@xmath1 absorption is detected may trace cosmological chemical evolution more reliably since they may comprise a narrower set of physical conditions .
the 9 known h@xmath1 absorption systems support this hypothesis : metallicity exhibits a faster , more well - defined evolution with redshift than in the general dla population . the dust - depletion factor and ,
particularly , h@xmath1 molecular fraction also show rapid increases with decreasing redshift .
we comment on possible observational selection effects which may bias this evolution .
larger samples of h@xmath1-bearing dlas are clearly required and may constrain evolution of the uv background and dla galaxy host type with redshift .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: apart from providing independent supporting evidence of the big bang , the detection and subsequent study of cosmological chemical evolution provides the empirical details of galaxy formation and evolution .
how primordial and processed gas is consumed by star formation , the dominant feedback processes and merging scenarios , may all contribute to the overall evolution of chemical abundances .
one high - precision probe of this evolution is the spectroscopic study of damped lyman-@xmath0 systems ( dlas ) : absorbers with neutral hydrogen column densities @xmath2 ..
Please generate the next two sentences of the article | although these observations demonstrate that dlas arise along lines of sight through distant galaxies , they do not directly disclose details such as the galaxy s morphology , luminosity , mass or age .
there exists substantial evidence that dlas arise in a variety of galaxy types . at low-@xmath3 ( @xmath4 ) , |
4,466 | Suppose that you have an abstract for a scientific paper: in the framework of cavity qed , we propose a quantum repeater scheme that uses coherent light and chains of atoms coupled to optical cavities .
in contrast to conventional repeater schemes , we avoid the usage of two - qubit quantum logical gates by exploiting solely the cavity qed evolution . in our previous paper [ d. gonta and p. van loock : phys .
rev .
a * 88 * , 052308 ( 2013 ) ] , we already proposed a quantum repeater in which the entanglement between two neighboring repeater nodes was distributed using controlled displacements of input coherent light , while the produced low - fidelity entangled pairs were purified using ancillary ( four - partite ) entangled states . in this paper ,
the entanglement distribution is realized using a sequence of controlled phase shifts and displacements of input coherent light .
compared to previous coherent - state - based distribution schemes for two - qubit entanglement , the present scheme relies only upon a simple discrimination of two coherent states with opposite signs , which can be performed in a quantum mechanically optimal fashion via a beam splitter and two on - off detectors .
the entanglement purification utilizes a scheme that avoids the usage of ancillary entangled resources .
our repeater scheme exhibits reasonable fidelities and repeater rates providing an attractive platform for long - distance quantum communication . .
And you have already written the first three sentences of the full article: in classical data transmission , repeaters are used to amplify data signals ( bits ) when they become weaker during their propagation through the transmission channel .
in contrast to classical information , the above mechanism is impossible to realize when the transmitted data signals are the carriers of quantum information ( qubits ) , which can not be amplified or cloned without destroying the encoded information @xcite , @xcite .
therefore , the carrier has to propagate along the entire length of the transmission channel which , due to various losses , leads to an exponentially decreasing probability to receive it intact at the end of the channel . to circumvent this problem ,.
Please generate the next two sentences of the article | the quantum repeater was proposed in the seminal ref .
@xcite that encapsulates three building blocks ( i ) entanglement distribution , ( ii ) entanglement purification , and ( iii ) entanglement swapping , which have to be applied sequentially . using the first building block , a large set of low - fidelity entangled qubit pairs |
4,467 | Suppose that you have an abstract for a scientific paper: in this talk we present our recent studies for the unpolarized fragmentation functions for the pion and kaon , employing the nonlocal chiral quark model , which manifests the nonlocal interaction between the quarks and pseudoscalar mesons , in the light - cone frame . it turns out that the nonlocal interaction produces considerable differences in comparison to typical local - interaction models . .
And you have already written the first three sentences of the full article: recently , there has been an increasing interest for the nonperturbative quantities of quantum chromodynamics ( qcd ) , observed in hard scattering processes , together with the experimental and theoretical progresses . among those physical quantities ,
fragmentation and parton - distribution functions reveal important information on the internal structures of the hadrons .
especially , the fragmentation function plays an crucial role in describing semi - inclusive hadron productions in electron annihilation and deeply inelastic scattering ( dis ) processes . in ref ..
Please generate the next two sentences of the article | @xcite , various fragmentation functions are intensively investigated using the @xmath0 evolution equation , such as the dokshitzer - gribov - lipatov - altarelli - parisi ( dglap ) equation , resulting in empirical parametrizations for those fragmentation functions .
more practical approaches have been done for the fragmentation functions , taking into account the effective chiral models for qcd , i.e. liner ( pseudoscalar , ps ) and nonlinear ( pseudovector , pv ) @xmath1 models ( or quark - pseudoscalar ( ps ) meson coupling model ) @xcite , and nambu - jona - lasinio ( njl ) model @xcite . |
4,468 | Suppose that you have an abstract for a scientific paper: we calculated the @xmath0he trimer and tetramer ground and excited states with the lm2m2 potential using our gaussian expansion method ( gem ) for _ ab initio _ variational calculations of few - body systems .
the method has extensively been used for a variety of three- , four- and five - body systems in nuclear physics and exotic atomic / molecular physics .
the trimer ( tetramer ) wave function is expanded in terms of symmetric three-(four-)body gaussian basis functions , ranging from very compact to very diffuse , without assuming any pair correlation function .
calculated results of the trimer ground and excited states are in excellent agreement with the literature .
binding energies of the tetramer ground and excited states are obtained to be 558.98 mk and 127.33 mk ( 0.93 mk below the trimer ground state ) , respectively .
we found that precisely the same shape of the short - range correlation ( @xmath1 ) in the dimer appear in the ground and excited states of trimer and tetramer .
the overlap function between the trimer excited state and the dimer and that between the tetramer excited state and the trimer ground state are almost proportional to the dimer wave function in the asymptotic region ( up to @xmath2 )
. also the pair correlation functions of trimer and tetramer excited states are almost proportional to the squared dimer wave function .
we then come to propose a model which predicts the binding energy of the first excited state of @xmath0he@xmath3 ( @xmath4 ) measured from the @xmath0he@xmath5 ground state to be nearly @xmath6 using the dimer binding energy @xmath7 . .
And you have already written the first three sentences of the full article: in early 1970 s , efimov pointed out a possibility of having an infinite number of three - body bound states even when none exists in the separate two - body subsystems @xcite .
this occurs when the two - body scattering length is much larger than the range of the two - body interaction . as a candidate of such three - body states ,
efimov discussed about the famous hoyle state @xcite ( the second @xmath8 state at 7.65mev in the @xmath9c nucleus ) taking a model of three @xmath10 particles ( clusters of three @xmath0he nuclei ) as well as about the three - nucleon bound state ( @xmath11h nuclei ) . in nuclear systems , the borromean states , weakly bound three - body states though having no bound two - body subsystems , are familiar but not classified as efimov states . in atomic systems , triatomic @xmath0he ( trimer ) have been expected to have bound states of efimov type since the realistic @xmath0he-@xmath0he interactions @xcite give a large @xmath0he-@xmath0he scattering length ( @xmath12 ) , much greater than the potential range ( @xmath13 ) , and a very small @xmath0he dimer binding energy ( @xmath14 mk ) ..
Please generate the next two sentences of the article | ( experimentally , ref .
@xcite evaluated a scattering length of @xmath15 @xmath16 and a binding energy of @xmath17 mk ) . as is mentioned in recent reviews about the @xmath0he trimer @xcite ( further references therein ) , i ) a lot of three - body calculations using the realistic pair potentials have shown that the @xmath0he trimer possesses two bound states with binding energies of nearly @xmath18 mk and @xmath19 mk , rather well established that , if the @xmath0he trimer excited state exist |
4,469 | Suppose that you have an abstract for a scientific paper: the quantum loop suppressed electroweak processes appear to be very sensitive probes for the symmetry - breaking mechanisms .
since the standard model does not involve massive neutrinos , baryon or lepton number violations and the cold dark matter particle , there are great expectations in search for physics beyond the standard model .
the lhc experiments reported no new physics , except for the appearance of the 125 gev heavy resonance .
if this resonance turns out to be a higgs boson , we shall be faced with the paradox that the standard model , as a theoretically and experimentally incomplete and defective theory , is confirmed .
if , on the other hand , this resonance is a scalar or pseudoscalar meson - a mixture of a ( pseudo)scalar glueball and toponium , one has to study alternative symmetry - breaking mechanisms .
this paper is devoted to the evaluations of the gauge invariant electroweak functions that are relevant for the suppressed electroweak processes within the sm or the uv finite theory in which the noncontractible space breaks the gauge symmetry .
deviations from the sm amplitudes range from 10% to 30% , thus being measurable at the lhcb and future superb factories .
the most recent result of the lhcb , measuring certain b meson branching fraction , appears to be lower than the sm prediction , thus favouring our theory of noncontractible space .
+ pacs numbers : 12.60.-i ; 12.15.-y ; 11.15.ex .
And you have already written the first three sentences of the full article: the physics of suppressed electroweak ( ew ) processes by quantum loops figure as the best window for search into the new physics territory .
more than three decades of the theoretical work strengthens our ability to predict their amplitudes with high precision .
while electroweak and hard qcd calculations rely on the perturbative framework and the renormalization theory , the hadron matrix elements are most accurately evaluated within the lattice qcd ..
Please generate the next two sentences of the article | the extensive search for new physics at the lhc reveals a new boson particle @xcite with a mass around 125 gev .
since the standard model ( sm ) does not contain massive neutrinos , lepton or baryon number violations and a candidate particle for the cold dark matter , it is very unlikely that the new particle is the sm higgs boson . |
4,470 | Suppose that you have an abstract for a scientific paper: we analyze the wilson loop for a pure yang - mills theory , using a decoupling solution in close agreement with lattice computations . at one - gluon exchange level
it is seen that the potential can not yield a linear rising contribution as expected for a confining theory . next - to - leading order correction gives rise to a quartic term for momenta in the gluon propagator that , in agreement with gribov s view , yields a linear confining term .
this correction is due to a two - loop or sunrise integral that we need to evaluate in the low - momenta limit . in the infrared regime , the physical consistency of the theory
is determined by a natural cut - off , arising from the integration of the classical equations of the theory , fixing in this way the regularization scheme . .
And you have already written the first three sentences of the full article: since the groundbreaking work of kenneth wilson @xcite , a proof of confinement for quantum chromodynamics in the continuum limit is lacking .
this is expected to be one of the major goals for our understanding of low - energy behavior of hadronic matter . since then , a lot of fundamental work has been pursued reaching a deeper comprehension of the problem @xcite .
stated in its simplest way , the confinement problem can be expressed through the behavior of the expectation value of the wilson loop that , for a free theory , is just reduced to the computation of a double path integral on the propagator of the theory ..
Please generate the next two sentences of the article | when this expectation takes the simple form @xmath0 , being @xmath1 the area spanned by the loop and @xmath2 a constant called string tension , one has that the _ area law _ holds and the potential rises linearly with the distance granting completely bounded states .
this result has been confirmed by computations on lattice @xcite and is generally stated as `` cornell potential '' being the sum of coulombian and linearly rising terms . |
4,471 | Suppose that you have an abstract for a scientific paper: we develop a series of molecular dynamics computer simulations of liquid water , performed with a polarizable potential model , to calculate the spinodal line and the curve of maximum density inside the metastable supercooled region .
after analysing the structural properties , the liquid spinodal line is followed down to @xmath0 k. a monotonic decrease is found in the explored region .
the curve of maximum density bends on approaching the spinodal line .
these results , in agreement with similar studies on non polarizable models of water , are consistent with the existence of a second critical point for water . .
And you have already written the first three sentences of the full article: liquid water behaviour as a function of temperature and pressure differs from that of most liquids . as a major example
the presence of a line of maximum density ( tmd line ) in the p - t phase diagram is most significant , as it divides the entire p - t phase diagram into two regions with remarkably different properties : the coefficient of thermal expansion is negative on the low - temperature side of the tmd line , while it is positive on the high - temperature side .
similarly , several other thermodynamic and dynamical quantities show peculiar properties ..
Please generate the next two sentences of the article | for instance the isothermal compressibility and heat capacity exhibit a minimum as a function of temperature and show an anomalous behavior more pronounced in the supercooled liquid state @xcite . when decreasing temperature in fact the coefficient of thermal expansion , the isothermal compressibility and the constant - pressure specific heat increase rapidly .
these quantities appear to diverge at a temperature @xmath1 if they are extrapolated below the lowest temperatures at which they are measurable ( @xmath2 c at @xmath3 @xmath4 ) @xcite . |
4,472 | Suppose that you have an abstract for a scientific paper: the higgs potential of the standard model with an additional real higgs singlet is studied in order to examine if it may allow the strongly first order electroweak phase transition .
it is found that there are parameter values for which this model at the one - loop level with finite temperature effect may allow the desired phase transition .
those parameter values also predict that the masses of the neutral scalar higgs bosons of the model are consistent with the present experimental bound , and that their productions in @xmath0 collisions may be searched at the proposed ilc with @xmath1 = 500 gev in the near future . .
And you have already written the first three sentences of the full article: the possibility of baryogenesis by means of electroweak phase transition has recently been widely examined , since the electroweak baryogenesis can in principle be tested in the future accelerator experiments [ 1 ] .
if the electroweak phase transition is strongly first order , it can fulfil the departure from thermal equilibrium which is one of the three conditions required by sakharov that are necessary for the dynamic generation of the baryon asymmetry during the evolution of the universe [ 2 ] .
it has already been observed that in the standard model ( sm ) the electroweak phase transition can not be strongly first order unless the mass of the scalar higgs boson is smaller than its lower bound set experimentally by lep [ 3 ] ..
Please generate the next two sentences of the article | the sufficient strength of the first order electroweak phase transition is essential for preserving the generated baryon asymmetry at the electroweak scale . in the literature ,
a number of articles have been devoted to study the possibility of accommodating the strongly first order electroweak phase transition in various models beyond the sm [ 4 ] . among them |
4,473 | Suppose that you have an abstract for a scientific paper: we present molecular dynamics simulations of the influence of point defects on the shear elastic coefficients of copper .
we find that vacancies do not influence these coefficients at all , while the introduction of interstitials causes a large reduction in the elastic coefficients .
the simulations establish a phase diagram of the melting temperature as a function of the density of interstitials . a crystal having no free surface undergoes bulk mechanical melting as a result of the vanishing of @xmath0 once the specific volume reaches a critical value , equal to the experimental volume of liquid phase .
this critical volume is history independent , in the sense that it can be reached either by heating the crystal or by adding defects at a constant temperature .
these results generalize the born model of melting for the case where point defects are present . ] .
And you have already written the first three sentences of the full article: single phase models of bulk melting usually treat this process as a destabilization of the solid due to proliferation of crystalline defects or excitations . among these
, lindemann suggested that melting occurs when the amplitude of atomic vibrations exceeds a critical value@xcite .
born proposed that melting is connected with the vanishing of the shear elastic coefficients @xcite ..
Please generate the next two sentences of the article | other models suggest that melting is a consequence of the proliferation of intrinsic crystalline defects such as vacancies @xcite .
however , there is no clear experimental evidence supporting any one of these models , all of which rely on a single type of defect or excitation . |
4,474 | Suppose that you have an abstract for a scientific paper: recently , there has been renewed interest in the search for low - mass magnetic monopoles . at the university of oklahoma we are performing an experiment ( fermilab e882 ) using material from the old d0 and cdf detectors to set limits on the existence of dirac monopoles of masses of the order of 500 gev . to set such limits ,
estimates must be made of the production rate of such monopoles at the tevatron collider , and of the binding strength of any such produced monopoles to matter .
here we sketch the still primitive theory of such interactions , and indicate why we believe a credible limit may still be obtained . on the other hand ,
there have been proposals that the classic euler - heisenberg lagrangian together with duality could be employed to set limits on magnetic monopoles having masses less than 1 tev , based on virtual , rather than real processes .
the d0 collaboration at fermilab has used such a proposal to set mass limits based on the nonobservation of pairs of photons each with high transverse momentum .
we critique the underlying theory , by showing that the cross section violates unitarity at the quoted limits and is unstable with respect to radiative corrections .
we therefore believe that no significant limit can be obtained from the current experiments , based on virtual monopole processes . .
And you have already written the first three sentences of the full article: the notion of magnetic charge has intrigued physicists since dirac @xcite showed that it was consistent with quantum mechanics provided a suitable quantization condition was satisfied : for a monopole of magnetic charge @xmath0 in the presence of an electric charge @xmath1 , that quantization condition is ( in this paper we use rationalized units ) @xmath2 where @xmath3 is an integer . for a pair of dyons , that is , particles carrying both electric and magnetic charge ,
the quantization condition is replaced by @xcite @xmath4 where @xmath5 and @xmath6 are the charges of the two dyons . ) below . ] with the advent of `` more unified '' non - abelian theories , classical composite monopole solutions were discovered @xcite .
the mass of these monopoles would be of the order of the relevant gauge - symmetry breaking scale , which for grand unified theories is of order @xmath7 gev or higher ..
Please generate the next two sentences of the article | but there are models where the electroweak symmetry breaking can give rise to monopoles of mass @xmath8 tev @xcite .
even the latter are not yet accessible to accelerator experiments , so limits on heavy monopoles depend either on cosmological considerations @xcite , or detection of cosmologically produced ( relic ) monopoles impinging upon the earth or moon @xcite . |
4,475 | Suppose that you have an abstract for a scientific paper: kaluza
klein compactifications with four - dimensional inflationary geometry combine the attractive idea of higher dimensional models with an attempt to incorporate four - dimensional early - time or late - time cosmology .
we analyze the mass spectrum of cosmological perturbations around such compactifications , including the scalar , vector and tensor sector . whereas scalar perturbations were discussed before ,
the spectrum of vector and tensor perturbations is a new result of this paper .
moreover , the complete analysis shows that possible instabilities of such compactifications are restricted to the scalar sector .
the mass squares of the vector and tensor perturbations are all non - negative .
we discuss form fields with a non - trivial background flux in the extra space as matter degrees of freedom .
they provide a source of scalar and vector perturbations in the effective four - dimensional theory .
we analyze the perturbations in freund - rubin compactifications .
although it can only be considered as a toy model , we expect the results to qualitatively generalize to similar configurations .
we find that there are two possible channels of instabilities in the scalar sector of perturbations , whose stabilization has to be addressed in any cosmological model that incorporates extra dimensions and form fields .
one of the instabilities is associated with the perturbations of the form field . .
And you have already written the first three sentences of the full article: in higher dimensional supergravity and string theories compactifications of spacetimes are an essential tool to make contact with the four - dimensional phenomenology . in the past
the majority of research was focused on the investigation of compactifications to four - dimensional minkowski or anti - de sitter spacetime .
klein spectrum of such compactifications was studied in detail to analyze the properties of the resulting supergravity theories @xcite . in contrary.
Please generate the next two sentences of the article | , cosmology motivates the study of effective four - dimensional geometries that correspond to an expanding universe .
the successful cosmological model with quasi - de sitter epochs during inflation and dark energy domination today gradually shifts the interest towards higher dimensional models that provide possibilities for incorporating effective four - dimensional cosmology . |
4,476 | Suppose that you have an abstract for a scientific paper: we present the first measurement of the rate of type ia supernovae at high redshift .
the result is derived using a large subset of data from the supernova cosmology project as described in more detail at this meeting by perlmutter et al .
( 1996 ) .
we present our methods for estimating the numbers of galaxies and the number of solar luminosities to which the survey is sensitive , the supernova detection efficiency and hence the control time .
we derive a rest - frame type ia supernova rate at @xmath0 of @xmath1 @xmath2 snu where the first uncertainty is statistical and the second includes systematic effects . .
And you have already written the first three sentences of the full article: beginning with the discovery of sn 1992bi ( perlmutter et al 1995 ) , we have developed search techniques and rapid analysis methods that allow systematic discovery and follow up of `` batches '' of high - redshift supernovae . the observing strategy developed compares large numbers of galaxies in each of @xmath350 fields observed twice with a separation of @xmath33 weeks .
this search schedule makes it possible to precisely calculate the `` control time , '' the effective time during which the survey is sensitive to a type ia event . for this analysis ,
we have studied a set of 52 similar search fields observed in december 1993 and january 1994 ..
Please generate the next two sentences of the article | the data were obtained using the `` thick '' @xmath4 eev5 camera at the 2.5 m isaac newton telescope , la palma .
the projected pixel size is @xmath5 , giving an image area of approximately @xmath6 . |
4,477 | Suppose that you have an abstract for a scientific paper: in paper i ( mickaelian et al .
1999 ) , we compared the surface density of qsos in the bright quasar survey ( bqs ) and in the first byurakan survey ( fbs ) and concluded that the completeness of the bqs is of the order of 70% rather than 3050% as suggested by several authors .
a number of new observations recently became available , allowing a re - evaluation of this completeness .
we now obtain a surface density of qsos brighter than @xmath0 16.16 in a subarea of the fbs covering @xmath12250 deg@xmath2 , equal to 0.012 deg@xmath3 ( 26 qsos ) , implying a completeness of 53@xmath410% . .
And you have already written the first three sentences of the full article: in paper i , by comparing the fbs ( markarian et al . 1989 ) and bqs ( green et al .
1986 ) surveys in their area in common , we derived a completeness of @xmath170% for the bqs .
a number of bright agns have since been discovered in the area which , together with our new spectroscopic observations , allowed us to refine our previous estimate of the bqs completeness ..
Please generate the next two sentences of the article | we have obtained new spectra for 11 fbs objects .
the observations were carried out on november 25 , 1998 and january 1415 , 1999 at the byurakan astrophysical observatory ( bao ) and at the observatoire de haute - provence ( ohp ) , respectively . |
4,478 | Suppose that you have an abstract for a scientific paper: of concern in the paper is a study of steady incompressible viscoelastic and electrically conducting fluid flow and heat transfer in a parallel plate channel with stretching walls in the presence of a magnetic field applied externally .
the flow is considered to be governed by walter s liquid b fluid .
the problem is solved by developing a suitable numerical method .
the results are found to be in good agrement with those of earlier investigations reported in existing scientific literatures .
the study reveals that a back flow occurs near the central line of the channel due to the stretching walls and further that this flow reversal can be stopped by applying a strong external magnetic field .
the study also shows that with the increase in the strength of the magnetic field , the fluid velocity decreases but the temperature increases .
thus the study bears potential applications in the study of the haemodynamic flow of blood in the cardiovascular system when subjected to an external magnetic field . + * keywords : * non - newtonian fluid , mhd flow , viscoelasticity , stretching walls , + heat transfer 0.8 cm -.1 in -.1 in 0.1 cm 20.5 cm [ section ] [ theorem]definition [ theorem]observation [ theorem ] [ theorem]proposition [ theorem]rule 22.5 cm = currsize .
And you have already written the first three sentences of the full article: in recent years , the study of magnetohydrodynamic ( mhd ) flow of blood through artery has gained considerable interest because of its physiological applications .
investigations on mhd flow and heat transfer of non - newtonian fluids over a stretching sheet also find many important applications in engineering and industry .
for example in the extrusion of a polymer sheet from a die , the sheet is sometimes stretched ..
Please generate the next two sentences of the article | the properties of the end product depend considerably on the rate of cooling . by drawing such a sheet in a visco - elastic electrically conducting
fluid subjected to the action of a magnetic field , the rate of cooling can be controlled and the final product can be obtained with desired characteristics . crane@xcite |
4,479 | Suppose that you have an abstract for a scientific paper: these are the notes for a course at the 18th brazilian school of probability held from august 3rd to 9th , 2014 in mambucaba .
the aim of the course is to introduce the basic problems of non linear pdes with stochastic and irregular terms .
we explain how it is possible to handle them using two main techniques : the notion of energy solutions @xcite and that of paracontrolled distributions , recently introduced in @xcite . in order to maintain a link with physical intuitions ,
we motivate such singular spdes via a homogenization result for a diffusion in a random potential . .
And you have already written the first three sentences of the full article: the aim of these lectures is to explain how to apply controlled path ideas @xcite to solve simple problems in singular pdes .
the hope is that the insight gained by doing so can inspire new applications or the construction of other more powerful tools to analyze a wider class of problems .
we discuss some problems involving singular stochastic non .
Please generate the next two sentences of the article | linear parabolic equations from the point of view of controlled paths .
to understand the origin of such singular equations , we have chosen to present the example of a homogenization problem for a singular potential in a linear parabolic equation . |
4,480 | Suppose that you have an abstract for a scientific paper: nucleon structure functions , as measured in deep - inelastic lepton scattering , are studied within a covariant scalar diquark spectator model . regarding the nucleon as an approximate two - body bound state of a quark and diquark ,
the bethe - salpeter equation ( bse ) for the bound state vertex function is solved in the ladder approximation .
the valence quark distribution is discussed in terms of the solutions of the bse .
= 15.9 cm = -1 cm adp-96 - 5/t210 , hep - ph/9603260 + _ talk given at the joint japan - australia workshop on quarks , hadrons + and nuclei , adelaide , south australia , november 15 - 24 , 1995 + ( to appear in the conference proceedings ) _ * structure functions of the nucleon + in a covariant scalar spectator model * + k. kusaka@xmath0 , g. piller@xmath1 , a.w .
thomas@xmath2 and a.g .
williams@xmath2 + _ @xmath0department of physics and mathematical physics , university of adelaide , + s.a . 5005 , australia _ + + _
@xmath3institute for theoretical physics , university of adelaide , s.a . 5005 ,
australia _ + e - mail : _ kkusaka , awilliam , [email protected]_ + .
And you have already written the first three sentences of the full article: in recent years many attempts have been made to understand nucleon structure functions as measured in lepton deep - inelastic scattering ( dis ) .
although perturbative qcd is successful in describing the dependence of structure functions on the squared momentum transfer , their magnitude is governed by the non - perturbative physics of composite particles , and is up to now not calculable directly from qcd .
a variety of models have been invoked to describe nucleon structure functions ..
Please generate the next two sentences of the article | the so called `` spectator model '' is a typical covariant approach amongst them@xcite . in this approach the leading twist , non - singlet quark distributions
are calculated from the process in which the target nucleon splits into a valence quark , which is scattered by the virtual photon , and a spectator system carrying baryon number @xmath4 . |
4,481 | Suppose that you have an abstract for a scientific paper: we numerically analyze the evolution of a long - duration gamma - ray burst jet as it leaves the progenitor star and propagates to the photospheric radius , where radiation can be released .
we find that the interaction of the relativistic material with the progenitor star has influences well beyond the stellar surface .
tangential collimation shocks are observed throughout the jet evolution , out to about 100 stellar radii , which is the whole range of our simulation .
we find that the jet is internally hot at the photospheric radius and we compute the photospheric emission .
the photosphere is a very efficient radiator , capable of converting more than half of the total energy of the jet into radiation .
we show that bright photospheres are a common feature of jets born inside massive progenitor stars and that this effect can explain the high radiative efficiency observed in long - duration bursts . .
And you have already written the first three sentences of the full article: long - duration gamma - ray bursts ( grbs ) are believed to arise when a very massive star collapses to a black hole , powering a hyper - relativistic outflow ( woosley 1993 ; hjorth et al .
2003 ; stanek et al . 2003 ; malesani et al . 2004
; woosley & bloom 2006 ) ..
Please generate the next two sentences of the article | they are the brightest explosions in the present day universe , releasing , in a matter of few tens of seconds , a large amount of energy ( @xmath0 erg ) in the form of a hot , possibly magnetized , outflow .
grbs are able to radiate a large fraction of their energy in the form of photons , with an efficiency sometimes approaching 100% ( zhang et al . |
4,482 | Suppose that you have an abstract for a scientific paper: binary linear @xmath0 $ ] codes that are proper for error detection are known for many combinations of @xmath1 and @xmath2 . for the remaining combinations , existence of proper codes
is conjectured . in this paper , a particular class of @xmath0 $ ] codes
is studied in detail . in particular
, it is shown that these codes are proper for many combinations of @xmath1 and @xmath2 which were previously unsettled .
error detection , proper codes , satisfactory codes , simplex codes , punctured codes , ugly codes . .
And you have already written the first three sentences of the full article: in this paper , we study binary linear @xmath0 $ ] codes ( codes of length @xmath1 and dimension @xmath2 ) used for error detection on the binary symmetric channel . a comprehensive introduction to the field
is given in @xcite .
the basic definitions are given in section [ sub : errordetection ] ..
Please generate the next two sentences of the article | a main quantity is the _ probability of undetected error _ of a code .
if the probability of undetected error is an increasing function on the interval @xmath3 $ ] , the code is known as _ proper _ for error detection . |
4,483 | Suppose that you have an abstract for a scientific paper: non - abelian lattice spin models with symmetry group @xmath0 or @xmath1 can be formulated in terms of link variables which are subject to the bianchi constraints .
using this representation we derive exact and local dual formulation for the partition function of such models on a cubic lattice in arbitrary dimension @xmath2 .
locality means that the dual action is given by a sum over some subset of hypercubes of the dual lattice and the interaction between dual variables ranges over one given hypercube .
dual variables are in general discrete - valued and live on @xmath3-cell of the dual lattice , in close analogy with the @xmath4 model .
we use our construction to study in details the dual of @xmath5 principal chiral model in two dimensions .
we give dual expressions also for two - point correlation function in arbitrary representation and for the free energy of defects .
leading terms of the asymptotic expansion of the dual boltzmann factor are computed and it is proven that at low temperatures it converges to a certain gaussian distribution uniformly in all fluctuations of dual variables . this result enables us to define the semiclassical limit of the dual formulation and to determine an analog of the vortex spin - wave representation for the partition function .
such representation is used to extract leading perturbative contribution to the correlation function which shows power - like decay at weak coupling .
we also present some analytical evidences that the low - temperature limit of the dual formulation is completely described by @xmath6-like approximation of @xmath5 matrix elements .
* dual formulations of non - abelian spin models : local representation and low - temperature asymptotics * * o. borisenko , v. kushnir * + .
And you have already written the first three sentences of the full article: two - dimensional ( @xmath7 ) lattice spin models , besides being interesting on their own right as models of ferromagnets can be viewed as mathematically well defined scheme of the nonperturbative regularization of quantum continuum field theories like @xmath0 principal chiral model or @xmath8 nonlinear sigma model . being a discrete theory lattice models can be simulated on computers by monte - carlo method , and this is nowadays the most important tool of obtaining physical results near the continuum limit . among major analytical methods one could mention the strong coupling expansion and the perturbation theory ( pt ) .
the pt is essentially the only analytical tool which provides systematic expansion of different physical quantities in the region of weak coupling , i.e. in the region relevant for the construction of the continuum limit .
however , at the best pt is only applicable for studying short - distance quantities and the most important and interesting phenomena , like the mass gap generation can not be described in its frameworks . when attempting to go beyond pt in the region of weak bare coupling , one runs into various mathematical problems , the most important being an absence of any analytical control over exponentially small contributions and , hence the absence of any reliable method to study long - distance physics where nonperturbative effects dominate even if they are exponentially suppressed ..
Please generate the next two sentences of the article | these facts impelled people to look for different , though equivalent representations which would allow to study the long - distance physics .
one of such popular and promising representations is known as a dual formulation and is based on a certain non - classical change of variables . |
4,484 | Suppose that you have an abstract for a scientific paper: we observe that , for fixed @xmath0 , each of the artin groups of finite type @xmath1 , @xmath2 , and affine type @xmath3 and @xmath4 is a central extension of a finite index subgroup of the mapping class group of the @xmath5-punctured sphere .
( the centre is trivial in the affine case and infinite cyclic in the finite type cases ) . using results of ivanov and korkmaz on abstract commensurators of surface mapping class groups we are able to determine the automorphism groups of each member of these four infinite families of artin groups . #
1#1 hs a rank @xmath6 _ coxeter matrix _ is a symmetric @xmath7 matrix @xmath8 with integer entries @xmath9 where @xmath10 for @xmath11 , and @xmath12 for all @xmath13 . given any rank @xmath6 coxeter matrix @xmath8 , the _ artin group _ of type @xmath8 is defined by the presentation @xmath14 adding the relations @xmath15 to this presentation
yields a presentation of the coxeter group of type @xmath8 generated by standard reflections @xmath16 and such that the rotation @xmath17 has order @xmath18 , for all @xmath19 . a coxeter matrix @xmath8 and its artin group @xmath20
are said to be of _ finite type _ if the associated coxeter group @xmath21 is finite , and of _ affine ( or euclidean ) type _ if @xmath21 acts as a proper , cocompact group of isometries on some euclidean space with the generators @xmath22 acting as affine reflections .
the information contained in the coxeter matrix @xmath8 is often displayed in the form of a graph , the _ coxeter graph _ , whose vertices are numbered @xmath23 and which has an edge labelled @xmath18 between the vertices @xmath24 and @xmath25 whenever @xmath26 or @xmath27 . with this particular convention ,
one usually suppresses the labels which are equal to @xmath28 ( but not the corresponding edges ! ) .
note that the absence of an edge between two vertices indicates that the corresponding generators of @xmath20 commute .
we say that an artin group is _ irreducible _ if its coxeter graph is connected and....
And you have already written the first three sentences of the full article: the following is a special case of theorem 8.5a of ivanov s survey article @xcite .
it is a consequence of ideas laid out in the papers of ivanov on the mapping class groups of higher genus orientable surfaces and the work of korkmaz @xcite on the complex of curves associated to an @xmath69-punctured sphere . for simplicity we shall write @xmath72 for the 2-sphere with @xmath69 points removed .
if @xmath73 is an orientable surface ( without boundary ) , we denote by @xmath74 the group of all diffeomorphisms of @xmath73 ( not necessarily respecting orientation ) modulo diffeotopy ..
Please generate the next two sentences of the article | [ ivanovkthm ] let @xmath75 .
if @xmath76 is an isomorphism between finite index subgroups @xmath77 , then @xmath78 is the restriction to @xmath79 of an inner automorphism of @xmath80 ( conjugation by some element @xmath81 ) . |
4,485 | Suppose that you have an abstract for a scientific paper: high - precision multi - band _ hst _ photometry reveals that the main sequence ( ms ) of the globular cluster ngc 6397 splits into two components , containing @xmath030% and @xmath070% of the stars .
this double sequence is consistent with the idea that the cluster hosts two stellar populations : ( _ i _ ) a primordial population that has a composition similar to field stars , and containing @xmath030% of the stars , and ( _ ii _ ) a second generation with enhanced sodium and nitrogen , depleted carbon and oxygen , and a slightly enhanced helium abundance ( @[email protected] ) .
we examine the color difference between the two sequences across a variety of color baselines and find that the second sequence is anomalously faint in @xmath2 .
theoretical isochrones indicate that this could be due to nh depletion . .
And you have already written the first three sentences of the full article: globular clusters ( gcs ) were once thought to be composed of stars of a single composition and a single age , with few exceptions ( such as @xmath3 centauri ) .
it had long been known that most clusters contained red - giant stars with anomalies in their light - element abundances ( kraft 1979 ) , but it was not clear whether this came as a result of internal mixing or a variation in the primordial abundances .
high - resolution spectroscopy ( e. g. ramirez & cohen 2002 , carretta et al ..
Please generate the next two sentences of the article | 2009 ) has shown that these abundance anomalies in the giants almost usually manifest themselves as an anticorrelation between na and o abundances , which is indicative of contamination from high - temperture hydrogen - burning products ( denisenkov & denisenkova 1989 ) .
a similar anticorrelation has also been observed in some un - evolved main - sequence ( ms ) stars ( gratton et al . |
4,486 | Suppose that you have an abstract for a scientific paper: our main result is a positive answer to the question whether one can find homogeneous distances on the heisenberg groups that have the besicovitch covering property ( bcp ) .
this property is well known to be one of the fundamental tools of measure theory , with strong connections with the theory of differentiation of measures .
we prove that bcp is satisfied by the homogeneous distances whose unit ball centered at the origin coincides with an euclidean ball .
such homogeneous distances do exist on any carnot group by a result of hebisch and sikora . in the heisenberg groups ,
they are related to the cygan - kornyi ( also called kornyi ) distance .
they were considered in particular by lee and naor to provide a counterexample to the goemans - linial conjecture in theoretical computer science .
to put our result in perspective , we also prove two geometric criteria that imply the non - validity of bcp , showing that in some sense our example is sharp .
our first criterion applies in particular to commonly used homogeneous distances on the heisenberg groups , such as the cygan - kornyi and carnot - carathodory distances that are already known not to satisfy bcp . to put a different perspective on these results and for sake of completeness
, we also give a proof of the fact , noticed by d. preiss , that in a general metric space , one can always construct a bi - lipschitz equivalent distance that does not satisfy bcp . .
And you have already written the first three sentences of the full article: covering theorems are known to be among some of the fundamental tools of measure theory .
they reflect the geometry of the space and are commonly used to establish connections between local and global behavior of measures .
covering theorems and their applications have been studied for example in @xcite and @xcite ..
Please generate the next two sentences of the article | there are several types of covering results , all with the same purpose : from an arbitrary cover of a set in a metric space , one extracts a subcover as disjointed as possible .
we will consider more specifically here the so - called besicovitch covering property ( bcp ) which originates from the work of besicovitch ( @xcite , @xcite , see also @xcite , @xcite , @xcite ) in connection with the theory of differentiation of measures . |
4,487 | Suppose that you have an abstract for a scientific paper: in this paper we describe a procedure for calculating the number of regular octahedrons that have vertices with coordinates in the set @xmath0 . as a result
, we introduce a new sequence in _ the online encyclopedia of integer sequences _ ( a178797 ) and list the first one hundred terms of it .
we adapt the method appeared in @xcite which was used to find the number of regular tetrahedra with coordinates of their vertices in @xmath0 .
the idea of this calculation is based on the theoretical results obtained in @xcite .
a new fact proved here helps increasing the speed of all the programs used before .
the procedure is put together in a series of commands written for maple .
[ section ] [ theorem ] proposition [ theorem ] corollary [ theorem ] lemma [ theorem ] definition [ theorem ] problem [ theorem ] conjecture [ theorem ] example [ theorem ] remark # 1#1 # 1#1 # 1*#1 * .
And you have already written the first three sentences of the full article: in this note we complete the work begun in the sequence of papers @xcite , @xcite-@xcite about equilateral triangles , regular tetrahedra , cubes , and regular octahedrons all with vertices having integer coordinates . very often we will refer to this property by saying that the various objects are in @xmath1 . strictly speaking these geometric objects
are defined as being more than the set of their vertices that determines them , but for us here , these are just the vertices .
so , for instance , an equilateral triangle is going to be a set of three points in @xmath2 for which the euclidean distances between every two of these points are the same ..
Please generate the next two sentences of the article | the main purpose of the paper is to take a close look at the regular octahedrons in @xmath2 .
the simplest example of a regular octahedron with integer coordinates for its vertices is @xmath3 , [ 1 , 0 , 1 ] , [ 1 , 1 , 0 ] , [ 1 , 1 , 2 ] , [ 1 , 2 , 1 ] , [ 2 , 1 , 1]\},\ ] ] which can be obtained from the usual unit cube in @xmath4 , multiplying the vertices by a factor of two and then taking the coordinates of the centers of the new faces . |
4,488 | Suppose that you have an abstract for a scientific paper: we describe a new approach to the schubert calculus on complete flag varieties using the volume polynomial associated with gelfand zetlin polytopes .
this approach allows us to compute the intersection products of schubert cycles by intersecting faces of a polytope . .
And you have already written the first three sentences of the full article: in this paper , we explore the connection between the schubert calculus and the volume polynomial on spaces of convex polytopes .
we give various representations of schubert cycles in a complete flag variety by sums of faces of the gelfand
zetlin polytope ..
Please generate the next two sentences of the article | our work is motivated by the rich interplay between algebraic geometry and convex polytopes , originally explored for toric varieties and recently extended to a more general setting in @xcite .
one of our main tools is a construction of @xcite , which , to every convex polytope @xmath0 , associates a graded commutative ring @xmath1 ( called the _ polytope ring _ ) satisfying the poincare duality ( see @xcite or section [ s.polytopes ] ) . for an _ integrally simple _ polytope @xmath2 ( simple means that there are exactly @xmath3 edges meeting at each vertex , and integrally simple means that primitive integer vectors parallel to the edges generate the lattice @xmath4 ) , the ring @xmath1 is isomorphic to the chow ring of the corresponding smooth toric variety @xmath5 @xcite . |
4,489 | Suppose that you have an abstract for a scientific paper: employing profits data of japanese companies in 2002 and 2003 , we confirm that pareto s law and the pareto index are derived from the law of detailed balance and gibrat s law .
the last two laws are observed beyond the region where pareto s law holds . by classifying companies into job categories
, we find that companies in a small scale job category have more possibilities of growing than those in a large scale job category .
this kinematically explains that the pareto index for the companies in the small scale job class is larger than that for the companies in the large scale job class .
pacs code : 04.60.nc + keywords : econophysics ; pareto law ; gibrat law ; detailed balance ; reflection law .
And you have already written the first three sentences of the full article: the pioneering discovery by pareto @xcite is not only an important cue for research in fractal but also a significant issue in economics .
the pareto law states that a cumulative number distribution @xmath0 obeys power - law for income @xmath1 which is larger than a certain observational threshold @xmath2 : @xmath3 where the exponent @xmath4 is called pareto index .
recently pareto s law is checked with high accuracy by using digitalized data @xcite ..
Please generate the next two sentences of the article | although the number of persons or companies in the range where pareto s law ( [ pareto ] ) holds is a few percent , the amount of the income occupies a large part of the total income .
high income persons or high income companies can , therefore , influence economics . |
4,490 | Suppose that you have an abstract for a scientific paper: a close study is made of the static structure factor for graphene in a magnetic field at integer filling factors @xmath0 , with focus on revealing possible signatures of @xmath1relativistic `` quantum field theory in the low - energy physics of graphene .
it is pointed out , in particular , that for graphene even the vacuum state has a nonzero density spectral weight , which , together with the structure factor for all @xmath0 , grows significantly with increasing wave vector ; such unusual features of density correlations are a ' ' relativistic " effect deriving from massless dirac quasiparticles in graphene .
remarkably it turns out that the zero - energy landau levels of electrons or holes , characteristic to graphene , remain indistinguishable in density response from the vacuum state , although they are distinct in hall conductance . .
And you have already written the first three sentences of the full article: a great deal of attention has recently been directed to graphene , a monolayer of carbon atoms , both experimentally @xcite and theoretically @xcite .
graphene is marked with its novel charge carriers that behave like massless dirac fermions with effective speed of light @xmath2
m / s @xmath3 ..
Please generate the next two sentences of the article | it thus provides a special opportunity to study @xmath1relativistic " quantum dynamics in condensed - matter systems .
experiments have revealed a number of exotic transport properties of graphene , such as the half - integer quantum hall ( qh ) effect and minimal conductivity . |
4,491 | Suppose that you have an abstract for a scientific paper: we have studied the properties of the stellar populations in the field of the ngc346 cluster in the small magellanic cloud , using the results of a novel self - consistent method that provides a reliable identification of pre - main sequence ( pms ) objects actively undergoing mass accretion , regardless of their age .
the 680 identified bona - fide pms stars show a bimodal age distribution , with two roughly equally numerous populations peaked respectively at @xmath0myr , and @xmath1myr .
we use the age and other physical properties of these pms stars to study how star formation has proceeded across time and space in ngc346 .
we find no correlation between the locations of young and old pms stars , nor do we find a correspondence between the positions of young pms stars and those of massive ob stars of similar age .
furthermore , the mass distribution of stars with similar age shows large variations throughout the region .
we conclude that , while on a global scale it makes sense to talk about an initial mass function , this concept is not meaningful for individual star - forming regions .
an interesting implication of the separation between regions where massive stars and low - mass objects appear to form is that high - mass stars might not be `` perfect '' indicators of star formation and hence a large number of low - mass stars formed elsewhere might have so far remained unnoticed .
for certain low surface density galaxies this way of preferential low - mass star formation may be the predominant mechanism , with the consequence that their total mass as derived from the luminosity may be severely underestimated and that their evolution is not correctly understood . .
And you have already written the first three sentences of the full article: with over 30 o - type stars amongst its denizens ( massey , parker & garmany 1989 ; evans et al .
2006 ) , the ngc346 cluster is the site of most intense star formation in the small magellanic cloud ( smc ) as well as one of the most active in the local group .
the massive young stars in ngc346 are responsible for the ionisation of the surrounding n66 nebula , the largest hii region in the smc ( henize 1956 ) ..
Please generate the next two sentences of the article | the location of ngc346 and n66 in the smc , their geometry and the limited amount of foreground extinction have made these regions an ideal place to study the effects of massive objects on the surrounding medium , including whether they can effectively trigger the formation of new generations of stars , as some theories of sequential star formation suggest ( e.g. elmegreen & lada 1977 ) . over the past 20 years , many authors have attempted to give an answer to these questions .
massey , parker & garmany ( 1989 ) conducted a photometric and spectroscopic study of ngc346 , revealing not only 33 o - type stars ( @xmath2 of which earlier than o@xmath3 ) , but also several lower - mass stars ( @xmath4m@xmath5 ) forming a distinct subgroup @xmath6 to the sw of the centre and with an estimated age of order 15myr . |
4,492 | Suppose that you have an abstract for a scientific paper: events with tagged photons in the process of electron positron annihilation into hadrons are considered .
the initial state radiation is suggested to scan the hadronic cross section with the energy .
qed radiative corrections are taken into account .
the results for the total and exclusive cross sections are given in an analytic form .
some numerical estimates are presented .
@xmath0 _ joint institute for nuclear research , dubna , 141980 , russia + @xmath1 _ institute of physics and technology , kharkov , 310108 , ukraine + @xmath2 _ dipartimento di fisica , universit di parma and infn , + gruppo collegato di parma , 43100 parma , italy _ _ _ + pacs 13.65.+i hadron production by electron positron annihilation , + 12.15.lk electroweak radiative corrections .
And you have already written the first three sentences of the full article: experiments with tagged photons , radiated from the initial state in electron proton and electron positron collisions , can become particularly attractive .
the reason is that these radiative processes will permit to extract information about the final states at continuously varying values of the collision energy . to investigate deep inelastic scattering the authors of ref .
@xcite suggested to use radiative events instead of running colliders at reduced beam energies ..
Please generate the next two sentences of the article | the method takes advantage of a photon detector ( pd ) placed in the very forward direction , as seen from the incoming electron beam . the effective beam energy , for each radiative event ,
is determined by the energy of the hard photon is observed in pd . |
4,493 | Suppose that you have an abstract for a scientific paper: we investigate the quantum phase transitions of the extended hubbard model at half - filling with periodic boundary conditions employing the entanglement of particles , as opposed to the more traditional entanglement of modes .
our results show that the entanglement has either discontinuities or local minima at the critical points .
we associate the discontinuities to first order transitions , and the minima to second order ones .
thus we show that the entanglement of particles can be used to derive the phase diagram , except for the subtle transitions between the phases sdw - bow , and the superconductor phases ts - ss . .
And you have already written the first three sentences of the full article: the connection between two important disciplines of physics , namely quantum information theory and condensed matter physics , has been the subject of great interest recently , generating much activity at the border of these fields , with numerous interesting questions addressed so far @xcite . in particular , the properties of entanglement in many - body systems , and the analysis of its behavior in critical systems deserve special attention . in this work
we deal with the entanglement of indistinguishable fermionic particles in the one dimensional extended hubbard model ( ehm ) .
we focus in the half - filling case ..
Please generate the next two sentences of the article | the model is a generalisation of the hubbard model @xcite , which encompasses more general interactions between the fermionic particles , such as an inter - site interaction , thus describing more general phenomena and a richer phase diagram .
precisely , it is given by , @xmath0 where @xmath1 is the lattice size , @xmath2 and @xmath3 are creation and annihilation operators , respectively , of a fermion with spin @xmath4 at site @xmath5 , @xmath6 , @xmath7 , and we consider periodic boundary conditions ( pbc ) , @xmath8 . |
4,494 | Suppose that you have an abstract for a scientific paper: the final results of the macro experiment on atmospheric neutrino oscillations are presented and discussed . the data concern different event topologies with average neutrino energies of @xmath0 and @xmath1 gev .
multiple coulomb scattering of the high energy muons in absorbers was used to estimate the neutrino energy of each event .
the angular distributions , the @xmath2 distribution , the particle ratios and the absolute fluxes all favour @xmath3 oscillations with maximal mixing and @xmath4 .
a discussion is made on the monte carlos used for the atmospheric neutrino flux .
some results on neutrino astrophysics are also briefly discussed .
+ _ keywords : astroparticle physics ; underground detectors ; neutrino oscillations .
+ pacs nos . : 13.15.+g ; 14.60.pq ; 96.40.de ; 96.40.tv_
[ 1]\{. .
And you have already written the first three sentences of the full article: macro was a large area multipurpose underground detector @xcite designed to search for rare events and rare phenomena in the penetrating cosmic radiation .
the experiment obtained important results on atmospheric @xmath5 oscillations and performed @xmath5 astronomy studies , indirect searches for wimps and searches for low energy @xmath6 from stellar gravitational collapses @xcite .
the detector was located in hall b of the underground gran sasso lab at an average rock overburden of 3700 m.w.e . ; it started data taking with part of the apparatus in @xmath7 ; it was completed in @xmath8 and was running in its final configuration until december 2000 ..
Please generate the next two sentences of the article | the detector had global dimensions of @xmath9 and provided a total acceptance to an isotropic flux of particles of @xmath10 .
the detector was composed of three horizontal layers of liquid scintillation counters , 14 layers of limited streamer tubes and one layer of nuclear track detectors , fig . |
4,495 | Suppose that you have an abstract for a scientific paper: we measured the near - infrared orbital light curve of the black hole binary a062000 in 1995 and 1996 .
the light curves show an asymmetric , double - humped modulation with extra emission in the peak at orbital phase 0.75 .
there were no significant changes in the shape of the light curve over the one - year observation period .
there were no sharp dips in the light curves nor reversals of the asymmetry between the two peaks as seen in earlier observations .
the light curves are well fit by models incorporating ellipsoidal variations from the mass - losing k - type star plus a beamed bright spot on the accretion disk around the compact star .
the long - term stability of the light curve shape rules out superhumps and star spots as sources of asymmetry when we observed a062000 .
the ellipsoidal variations yield a lower limit @xmath0 on the orbital inclination .
the light curves show no eclipse features , which places an upper limit @xmath1 .
this range of inclinations constrains the mass of the compact object to @xmath2 @xmath3 .
the light curves do not further constrain the orbital inclination because the contribution of the accretion disk to the observed flux is unknown .
we argue that a previous attempt to measure the near - infrared flux from the accretion disk using the dilution of the @xmath4co(2,0 ) bandhead in the spectrum of the k star is not reliable because the band strength depends strongly on surface gravity . .
And you have already written the first three sentences of the full article: the bright x - ray nova a062000 ( v616 mon ) was discovered when it erupted in 1975 @xcite .
observations obtained after its return to quiescence revealed that a062000 is an interacting binary system with a k star donating mass to a compact star via an accretion disk @xcite .
early fits to the radial velocity variations of the k star gave a semi - amplitude of @xmath5 km s@xmath6 , which , when combined with the orbital period ( @xmath7 hr ) , yielded a mass function @xmath8 @xmath3 ..
Please generate the next two sentences of the article | the mass function equals the minimum dynamical mass of the compact star .
since the mass function for a062000 is greater than the theoretical maximum mass for a neutron star , a062000 became a strong candidate for a black hole binary @xcite . |
4,496 | Suppose that you have an abstract for a scientific paper: given a finite simple graph @xmath0 with chromatic number @xmath1 and chromatic polynomial @xmath2 .
every vertex graph coloring @xmath3 of @xmath4 defines an index @xmath5 satisfying the poincar - hopf theorem @xcite @xmath6 . as a variant to the index expectation result
@xcite we prove that @xmath7 $ ] is equal to curvature @xmath8 satisfying gauss - bonnet @xmath9 @xcite , where the expectation is the average over the finite probability space containing the @xmath10 possible colorings with @xmath1 colors , for which each coloring has the same probability . .
And you have already written the first three sentences of the full article: differential geometric ideas were used in graph coloring problems early on .
wernicke @xcite promoted already gauss - bonnet type ideas to the four color problem and used what we today call curvature to graph theory . the discharging method introduced by heesch @xcite
was eventually used by appel and haken @xcite to prove the four color theorem ..
Please generate the next two sentences of the article | this method is conceptionally related to geometric evolution methods : deform the geometry until a situation is reached which can be understood by classification .
birkhoff @xcite and later tutte attached polynomials to graphs which relate modern topological invariants like the jones polynomial . |
4,497 | Suppose that you have an abstract for a scientific paper: extending deep observations of the neutral atomic hydrogen ( hi ) to the environment around galaxy groups can reveal a complex history of group interactions which is invisible to studies that focus on the stellar component .
hickson compact group 44 ( hcg 44 ) is a nearby example and we have combined hi data from the karoo array telescope , westerbork synthesis radio telescope , and arecibo legacy fast alfa survey , in order to achieve high column density sensitivity ( @xmath0 @xmath1 ) to the neutral gas over a large field - of - view beyond the compact group itself . we find the giant hi tail north of hcg 44 contains @xmath2 m@xmath3 of gas and extends 450 kpc from the compact group : twice as much mass and 33% further than previously detected .
however , the additional gas is still unable to account for the known hi deficiency of hcg 44 .
the tail likely formed through a strong tidal interaction and hi clouds in the tail have survived for 1 gyr or more after being stripped .
this has important implications for understanding the survival of neutral clouds in the intragroup and circumgroup medium , and we discuss their survival in the context of simulations of cold gas in hot halos .
hcg 44 is one of a growing number of galaxy groups found to have more extended hi in the intragroup and circumgroup medium than previously measured .
our results provide constraints for simulations on the properties of galaxy group halos , and reveal a glimpse of what will be seen by future powerful hi telescopes and surveys .
[ firstpage ] galaxies : evolution galaxies : interactions galaxies : ism radio lines : galaxies galaxies : groups : individual : hcg 44 .
And you have already written the first three sentences of the full article: large area redshift surveys such as sdss @xcite and gama @xcite have established a new paradigm regarding the clustering of galaxies @xcite .
the evolutionary effects imposed by this range of environments are not fully understood , largely due to the complexity of n - body interactions on star formation and gas dynamics .
however , the relatively unexplored regime of neutral hi in the context of galaxy groups has the potential to revolutionise our understanding of the mechanisms influencing how galaxies mature ..
Please generate the next two sentences of the article | targeted observations of the hi content in nearby groups have often revealed the presence of intragroup material , for example , with the very large array ( vla e.g. * ? ? ?
* ; * ? ? ? |
4,498 | Suppose that you have an abstract for a scientific paper: the effect of interstitial hydrogen on the elastic properties of @xmath0-iron is investigated using _
ab initio _ density functional theory .
we find that while the overall strength properties are reduced by h , the effects are mainly due to the resulting local volume expansion .
we use these concentration - dependent elastic moduli to model the effects of homogeneous strain fields on h solubility and make extrapolations to h - solubility in the spatially - varying strain fields of realistic dislocations .
we find that h is strongly trapped by dislocations of both the edge and screw variety , leading to a remarkable increase in the local h concentration near the dislocation cores .
the strain dependence of the solution energy leading to accumulation of h near dislocation cores , as well as the reduction of elastic moduli which our calculations predict , is consistent with numerous experimental studies which indicate that the trapping of h near dislocations plays a significant role in the embrittlement of iron and steels . .
And you have already written the first three sentences of the full article: hydrogen degrades the performance of many metals by lowering the failure stress , leading to fracture at unpredictable loading conditions @xcite .
several mechanisms have been proposed to explain the h - embrittlement of iron : the hydrogen - enhanced decohesion ( hede ) mechanism @xcite , h - vacancy effects @xcite , hydrogen - enhanced localised plasticity ( help ) @xcite , or a combination thereof .
however , none of these explanations alone seems to provide a complete explanation of the experimentally - observed features of h - embrittlement . in the hede mechanism ,.
Please generate the next two sentences of the article | h weakens the cohesive bonds between the metal atoms , leading to failure at interfaces , as h exhibits increased solubility in the tensile strain field of a crack opening .
vacancies containing h can order themselves along critical slip directions , leading to fracture @xcite . within the help mechanism , |
4,499 | Suppose that you have an abstract for a scientific paper: we study the family of closed riemannian @xmath0-manifolds with holonomy group isomorphic to @xmath1 , which we call generalized hantzsche - wendt manifolds .
we prove results on their structure , compute some invariants , and find relations between them , illustrated in a graph connecting the family . .
And you have already written the first three sentences of the full article: a flat manifold is a closed riemannian manifold with zero sectional curvature . from bieberbach theorems
, it is known that in each dimension there is only a finite number of such manifolds , up to affine equivalence , and the problem of classifying them is important .
recently , this has been achieved up to dimension six ( cf.@xcite ) , but it is not possible to do it in general ..
Please generate the next two sentences of the article | hence some interesting families of flat manifolds have been considered , as for instance those with first betti number zero or those with holonomy group @xmath2 .
the purpose of this article is to study another special class of flat manifolds , namely those of dimension @xmath0 with holonomy group isomorphic to @xmath3 . in dimension two |
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