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Suppose that you have an abstract for a scientific paper: it is now widely accepted that dense filaments of molecular gas are integral to the process of stellar birth and potential star - forming cores often appear embedded within these filaments . although numerical simulations have largely succeeded in reproducing filamentary structure in dynamic environments such as in turbulent gas and while analytic calculations predict the formation of dense gas filaments via radial collapse , the exact process(es ) that generate / s such filaments which then form prestellar cores within them , is unclear . in this work we therefore study numerically the formation of a dense filament using a relatively simple set - up of a uniform - density cylinder in pressure equilibrium with its confining medium . in particular , we examine if its propensity to form a dense filament and further , to the formation of prestellar cores within this filament bears on the gravitational state of the initial volume of gas . we report a radial collapse leading to the formation of a dense filamentary cloud is likely when the initial volume of gas is at least critically stable ( characterised by the approximate equality between the mass line - density for this volume and its maximum value ) . though self - gravitating , this volume of gas , however , is not seen to be in free - fall . this post - collapse filament then fragments along its length due to the growth of a jeans - like instability to form prestellar cores like _ beads on a string_. we suggest , dense filaments in typical star - forming clouds classified as gravitationally super - critical under the assumption of : ( i ) isothermality when in fact , they are not , and ( ii ) extended radial profiles as against one that is pressure - truncated , thereby causing significant over - estimation of their mass line - density , are unlikely to experience gravitational free - fall . the radial density and temperature profile derived for this post - collapse filament is consistent with that deduced for typical filamentary clouds mapped in.... And you have already written the first three sentences of the full article: gas in giant molecular clouds ( gmcs ) is distributed non - uniformly and appears to aggregate itself into isolated dense clumps or more contiguous and elongated , filament - like structures . detailed observations of potential star - forming clouds have demonstrated the ubiquitous nature of filamentary clouds . for example , giant molecular filaments on scales of a few parsecs have been reported in the inter - arm regions of the milky - way ( ragan _ et al .. Please generate the next two sentences of the article

_ 2014 ; higuchi _ et al . _ 2014 and other references therein ) .

Suppose that you have an abstract for a scientific paper: we present the results of a new calculation of the photodisintegration of ultrahigh energy cosmic - ray ( uhcr ) nuclei in intergalactic space . the critical interactions for energy loss and photodisintegration of uhcr nuclei occur with photons of the 2.73 k cosmic background radiation ( cbr ) and with photons of the infrared background radiation ( ibr ) . we have reexamined this problem making use of a new determination of the ibr based on empirical data , primarily from iras galaxies , consistent with direct measurements and upper limits from tev @xmath0-ray observations . we have also improved the calculation by including the specific threshold energies for the various photodisintegration interactions in our monte carlo calculation . with the new smaller ibr flux , the steepness of the wien side of the now relatively more important cbr makes their inclusion essential for more accurate results . our results indicate a significant increase in the propagation time of uhcr nuclei of a given energy over previous results . we discuss the possible significance of this for uhcr origin theory . # 1#23.6pt . And you have already written the first three sentences of the full article: shortly after the discovery of the cosmic microwave background radiation ( cbr ) , it was shown that cosmic ray protons above @xmath160 eev ( @xmath2ev ) should be attenuated by photomeson interactions with cbr photons ( @xcite ) . it was later calculated that heavier cosmic ray nuclei with similar _ total _ energies would also be attenuated , but by a different process , _ viz . _ , photodisintegration interactions with ibr photons ( @xcite ) , hereafter designated psb ). Please generate the next two sentences of the article

. we will refer to such cosmic rays of total energies above 10 eev as ultrahigh energy cosmic rays ( uhcr ) . in the more conventional scenario , uhcrs are charged particles which must be accelerated to ultrahigh energies by electromagnetic processes at extragalactic sites , both because there are no known sites in our galaxy which can accelerate and magnetically contain them and also because most of the observed uhcr air shower events arrive from directions outside of the galactic plane . although such acceleration of charged particles to energies above 100 eev in cosmic sources pushes our present theoretical ideas to their extreme , it has been suggested that it may occur in hot spots in the lobes of radio galaxies ( @xcite ) .

Suppose that you have an abstract for a scientific paper: quantum systems out of equilibrium are now a subject of intensive research both in theoretical and experimental physics . in this paper we study periodically modulated quantum systems which are in contact with a stationary environment . within the framework of lindblad quantum master equation , the asymptotic states of such systems are described by time - periodic density operators . resolution of these operators is a non - trivial computational task . approaches based on spectral and iterative methods are restricted to systems with the dimension of the hosting hilbert space @xmath0 , while the direct long - time integration of the master equation becomes problematic for @xmath1 . to overcome these limitations we use the quantum trajectory method which unravels the deterministic master equation for the density operator into a set of stochastic processes for wave functions . this method avoids calculations of the kernel of the floquet superoperator ; instead the asymptotic density matrix is calculated by performing a statistical sampling preceded by a long transient propagation . we present a high - accuracy realization of this idea based on exponential propagators combined with a time - stepping technique . employing a scalable model of interacting bosons hoping over a dimer , we test the performance of the algorithm on a supercomputer . we demonstrate that the algorithm allows to resolve non - equilibrium asymptotic states of model systems with @xmath2 on a small computer cluster thus reaching the scale on which numerical studies of isolated periodically - modulated systems are currently performed . open quantum systems , lindblad equation , periodic modulations , quantum trajectories . And you have already written the first three sentences of the full article: any _ in vivo _ quantum system is in a contact with its environment . although typically weak , this interaction becomes relevant when studying the evolution of a system over long time scales . in particular , the asymptotic state of such an _ open _ system depends both on the unitary action induced by the system hamiltonian , and the action of the environment , conventionally called ` dissipation ' . a recent idea of `` engineering by dissipation '' @xcite ,. Please generate the next two sentences of the article

the creation of designated pure and highly entangled states of many - body quantum systems by using specially designed dissipative operators , has promoted dissipation to the same level of importance as the underlying unitary dynamics . the use of time - periodic modulations constitutes another channel to impact states of a quantum system . in the coherent limit ,

Suppose that you have an abstract for a scientific paper: the point sets of all known optimal rectilinear drawings of @xmath0 share an unmistakeable clustering property , the so called _ 3decomposability_. it is widely believed that the underlying point sets of all optimal rectilinear drawings of @xmath0 are @xmath1decomposable . we give a lower bound for the minimum number of @xmath2sets in a @xmath1decomposable @xmath3point set . as an immediate corollary , we obtain a lower bound for the crossing number @xmath4 of any rectilinear drawing @xmath5 of @xmath0 with underlying @xmath1decomposable point set , namely @xmath6 . this closes this gap between the best known lower and upper bounds for the rectilinear crossing number @xmath7 of @xmath0 by over 40% , under the assumption of @xmath1decomposability . . And you have already written the first three sentences of the full article: figure [ fig : figure1 ] shows the point set of an optimal ( crossing minimal ) rectilinear drawing of @xmath8 , with an evident partition of the @xmath9 vertices into @xmath1 highly structured clusters of @xmath1 vertices each : [ fig : figure1 ] are clustered into @xmath1 sets.,width=113 ] a similar , natural , highly structured partition into @xmath1 clusters of equal size is observed in _ every _ known optimal drawing of @xmath0 , for every @xmath3 multiple of @xmath1 ( see @xcite ) . even for those values of @xmath3 ( namely , @xmath10 ) for which the exact rectilinear crossing number @xmath7 of @xmath0 is not known , the best available examples also share this property @xcite . in all these examples , a set @xmath11 of @xmath3 points in general position is partitioned into sets @xmath12 and @xmath13 , with @xmath14 with the following properties : \(i ) there is a directed line @xmath15 such that , as we traverse @xmath15 , we find the @xmath15orthogonal projections of the points in @xmath16 , then the @xmath15orthogonal projections of the points in @xmath17 , and then the @xmath15orthogonal projections of the points in @xmath13 ; \(ii ) there is a directed line @xmath18 such that , as we traverse @xmath18 , we find the @xmath18orthogonal projections of the points in @xmath17 , then the @xmath18orthogonal projections of the points in @xmath16 , and then the @xmath18orthogonal projections of the points in @xmath13 ; and \(iii ) there is a directed line @xmath19 such that , as we traverse @xmath19 , we find the @xmath19orthogonal projections of the points in @xmath17 , then the @xmath19orthogonal projections of the points in @xmath13 , and then the @xmath19orthogonal projections of the points in @xmath16 . * definition * a point set that satisfies conditions ( i)(iii ) above is @xmath1 _ decomposable_.. Please generate the next two sentences of the article

we also say that the underlying rectilinear drawing of @xmath0 is @xmath1_decomposable_. a possible choice of @xmath20 , and @xmath19 for the example in figure [ fig : figure1 ] is illustrated in figure [ fig : figure2 ] . [ ht ] 1 cm 0.5 cm it is widely believed that all optimal rectilinear drawings of @xmath0 are @xmath1decomposable .

Suppose that you have an abstract for a scientific paper: we have directly measured the energy threshold and efficiency for bubble nucleation from iodine recoils in a cf@xmath0i bubble chamber in the energy range of interest for a dark matter search . these interactions can not be probed by standard neutron calibration methods , so we develop a new technique by observing the elastic scattering of @xmath1 negative pions . the pions are tracked with a silicon pixel telescope and the reconstructed scattering angle provides a measure of the nuclear recoil kinetic energy . the bubble chamber was operated with a nominal threshold of @xmath2 . interpretation of the results depends on the response to fluorine and carbon recoils , but in general we find agreement with the predictions of the classical bubble nucleation theory . this measurement confirms the applicability of cf@xmath0i as a target for spin - independent dark matter interactions and represents a novel technique for calibration of superheated fluid detectors . recent years have seen a resurgence in the use of superheated liquids and bubble chambers as continuously sensitive nuclear recoil detectors searching for dark matter in the form of weakly interacting massive particles ( wimps)@xcite . at a low degree of superheat , bubble chambers are insensitive to minimum ionizing backgrounds that normally plague wimp searches but retain sensitivity to the nuclear recoils that would be characteristic of wimp scattering . in a superheated liquid the process of radiation - induced bubble nucleation is described by the classical `` hot spike '' model @xcite . for the phase transition to occur , the energy deposited by the particle must create a critically sized bubble , requiring a minimum energy deposition in a volume smaller than the critical bubble . under mildly superheated conditions , the latter requirement renders the bubble chamber insensitive to minimum ionizing particles . the radius of the critical bubble is given by the condition that the bubble be in ( unstable ) equilibrium with the.... And you have already written the first three sentences of the full article: our bubble chambers are insensitive to minimum ionizing particles , allowing us to exploit a new calibration technique using charged pions as wimp surrogates to produce nuclear recoils by strong elastic scattering . we measure the pion scattering angle using silicon pixel detectors . the nuclear recoil kinetic energy can be calculated by @xmath26 on an event by event basis , where @xmath27 is the beam momentum , @xmath28 the scattering angle , and @xmath29 the nuclear mass of the target . for a cf@xmath0i target. Please generate the next two sentences of the article

, a measured scattering angle corresponds to a different recoil energy depending on which nucleus is involved in the interaction ; in this paper , we will refer to iodine equivalent recoil energy , @xmath30 , as the energy given to an iodine nucleus for a given pion scattering angle . for a @xmath1 pion beam , approximately @xmath31 of the rate of pions scattering into angles corresponding to @xmath30 between 5 and 20 kev is due to elastic scattering on iodine , with smaller contributions from carbon , fluorine , and inelastic scattering @xcite .

Suppose that you have an abstract for a scientific paper: we have calculated the nonlinear current of a number of single band s - wave electron - phonon superconductors . among issues considered were those of dimensionality , strong electron - phonon coupling , impurities , and comparison with bcs . for the case of two bands , particular attention is paid to the role of anisotropy , the integration effects of the off - diagonal electron - phonon interaction , as well as inter- and intraband impurities . for the specific case of mgb@xmath0 , we present results based on the known microscopic parameters of band theory . . And you have already written the first three sentences of the full article: with the advent of high temperature superconductivity in the cuprates and the possibility of exotic gap symmetry including nodal behavior , a renewed effort to find novel experimental probes of order parameter symmetry has ensued . one result of this effort was the proposal by sauls and co - workers@xcite to examine the nonlinear current response of d - wave superconductors . they showed that a nonanalyticity in the current - velocity relation at temperature @xmath1 is introduced by the presence of nodes in the order parameter .. Please generate the next two sentences of the article

one prediction was that an anisotropy should exist in the nonlinear current as a function of the direction of the superfluid velocity relative to the position of the node . this would be reflected in an anisotropy of a term in the inverse penetration depth which is linear in the magnetic field @xmath2 .

Suppose that you have an abstract for a scientific paper: three disjoint rays in @xmath0 form _ borromean rays _ provided their union is knotted , but the union of any two components is unknotted . we construct infinitely many borromean rays , uncountably many of which are pairwise inequivalent . we obtain uncountably many borromean hyperplanes . . And you have already written the first three sentences of the full article: for proper , locally flat embeddings in @xmath1 , it is well - known that : 1 . [ rlt ] a ray (= copy of @xmath2 ) knots if and only if @xmath3 . [ hlt ] a hyperplane (= copy of @xmath4 ) knots if and only if @xmath3 . both facts hold in the smooth , piecewise linear , and topological categories @xcite .. Please generate the next two sentences of the article

fox and artin discovered the first knotted ray @xcite . the boundary of a closed regular neighborhood of any knotted ray is a knotted hyperplane . for @xmath5 ,

Suppose that you have an abstract for a scientific paper: based on a recent formulation of the @xmath0parameter of a photonic crystal fiber we provide numerically based empirical expressions for this quantity only dependent on the two structural parameters the air hole diameter and the hole - to - hole center spacing . based on the unique relation between the @xmath0parameter and the equivalent mode field radius we identify how the parameter space for these fibers is restricted in order for the fibers to remain single mode while still having a guided mode confined to the core region . 10 s. g. johnson and j. d. joannopoulos , `` block - iterative frequency - domain methods for axwell s equations in a planewave basis , '' opt . express * 8 * , 173 ( 2001 ) , + http://www.opticsexpress.org/abstract.cfm?uri=opex-8-3-173 . t. p. white , b. t. kuhlmey , r. c. mcphedran , d. maystre , g. renversez , c. m. de sterke , and l. c. botton , `` multipole method for microstructured optical fibers . i. formulation , '' j. opt . soc . am . b * 19 * , 2322 ( 2002 ) . j. c. knight , t. a. birks , p. s. j. russell , and d. m. atkin , `` all - silica single - mode optical fiber with photonic crystal cladding , '' opt . lett . * 21 * , 1547 ( 1996 ) . a. w. snyder and j. d. love , _ optical waveguide theory _ ( chapman & hall , new york , 1983 ) . d. marcuse , `` gaussian approximation of the fundamental modes of graded - index fibers , '' j. opt . . am . * 68 * , 103 ( 1978 ) . n. a. mortensen , j. r. folkenberg , m. d. nielsen , and k. p. hansen , `` modal cut - off and the @xmath0parameter in photonic crystal fibers , '' opt . lett . * 28 * , 1879 ( 2003 ) . b. t. kuhlmey , r. c. mcphedran , and c. m. de sterke , `` modal cutoff in microstructured optical fibers , '' opt . lett . * 27 * , 1684 ( 2002 ) . j. r. folkenberg , n. a. mortensen , k. p. hansen , t. p. hansen , h. r. simonsen , and c. jakobsen , `` experimental investigation of cut - off phenomena in non - linear photonic crystal fibers.... And you have already written the first three sentences of the full article: theoretical descriptions of photonic crystal fibers ( pcfs ) have traditionally been restricted to numerical evaluation of maxwell s equations . in the most general case , a plane wave expansion method with periodic boundary conditions is employed @xcite while other methods , such as the multipole method @xcite , take advantage of the localized nature of the guided modes and to some extend the circular shape of the air - holes . the reason for the application of these methods is the relatively complex dielectric cross section of a pcf for which rotational symmetry is absent .. Please generate the next two sentences of the article

the aim of this work is to provide a set of numerically based empirical expressions describing the basic properties such as cutoff and mode - field radius of a pcf based on the fundamental geometrical parameters only . we consider the fiber structure first studied by knight _

Suppose that you have an abstract for a scientific paper: 1-nearest neighbor with the dynamic time warping ( dtw ) distance is one of the most effective classifiers on time series domain . since the global constraint has been introduced in speech community , many global constraint models have been proposed including sakoe - chiba ( s - c ) band , itakura parallelogram , and ratanamahatana - keogh ( r - k ) band . the r - k band is a general global constraint model that can represent any global constraints with arbitrary shape and size effectively . however , we need a good learning algorithm to discover the most suitable set of r - k bands , and the current r - k band learning algorithm still suffers from an overfitting phenomenon . in this paper , we propose two new learning algorithms , i.e. , band boundary extraction algorithm and iterative learning algorithm . the band boundary extraction is calculated from the bound of all possible warping paths in each class , and the iterative learning is adjusted from the original r - k band learning . we also use a silhouette index , a well - known clustering validation technique , as a heuristic function , and the lower bound function , lb_keogh , to enhance the prediction speed . twenty datasets , from the workshop and challenge on time series classification , held in conjunction of the sigkdd 2007 , are used to evaluate our approach . . And you have already written the first three sentences of the full article: classification problem is one of the most important tasks in time series data mining . a well - known 1-nearest neighbor ( 1-nn ) with dynamic time warping ( dtw ) distance is one of the best classifier to classify time series data , among other approaches , such as support vector machine ( svm ) @xcite , artificial neural network ( ann ) @xcite , and decision tree @xcite . for the 1-nn classification , selecting an appropriate distance measure is very crucial ; however , the selection criteria still depends largely on the nature of data itself , especially in time series data .. Please generate the next two sentences of the article

though the euclidean distance is commonly used to measure the dissimilarity between two time series , it has been shown that dtw distance is more appropriate and produces more accurate results . sakoe - chiba band ( s - c band ) @xcite originally speeds up the dtw calculation and later has been introduced to be used as a dtw global constraint .

Suppose that you have an abstract for a scientific paper: for random matrices with tree - like structure there exists a recursive relation for the local green functions whose solution permits to find directly many important quantities in the limit of infinite matrix dimensions . the purpose of this note is to investigate and compare expressions for the spectral density of random regular graphs , based on easy approximations for real solutions of the recursive relation valid for trees with large coordination number . the obtained formulas are in a good agreement with the results of numerical calculations even for small coordination number . . And you have already written the first three sentences of the full article: matrices with random ( or pseudo - random ) elements appear naturally in many different problems and are well investigated in physical and mathematical literature ( see e.g. @xcite ) . in this note we consider a special class of sparse random matrices , namely , matrices associated with tree ( or tree - like ) structures . a fundamental property of such matrices is that the number of non - zero elements in each row and column either remains finite or grows much slowly than the matrix dimension when the latter increases . as usual , a ( connected ). Please generate the next two sentences of the article

tree is a graph where any pair of vertices is connected by only one path without repeating vertices . vertices are labeled by integers . if a symmetric ( or hermitian ) matrix @xmath0 is such that its entries @xmath1 , @xmath2 , are non - zero if and only if vertices @xmath3 and @xmath4 are connected on a given tree , then the matrix @xmath0 is said to be associated with the tree .

Suppose that you have an abstract for a scientific paper: spin and chirality orderings of the three - dimensional heisenberg spin glass under magnetic fields are studied by large - scale equilibrium monte carlo simulations . it is found that the chiral - glass transition and the chiral - glass ordered state , which are essentially of the same character as their zero - field counterparts , occur under magnetic fields . the chiral - glass ordered state exhibits a one - step - like peculiar replica - symmetry breaking in the chiral sector , while it does not accompany the spin - glass order perpendicular to the applied field . critical perperties of the chiral - glass transition are different from those of the standard ising spin glass . magnetic phase diagram of the model is constructed , which reveals that the chiral - glass state is quite robust against magnetic fields . the chiral - glass transition line has a character of the gabay - toulouse line of the mean - field model , yet its physical origin being entirely different . these numerical results are discussed in light of the recently developed spin - chirality decoupling - recoupling scenario . implication to experimental phase diagram is also discussed . . And you have already written the first three sentences of the full article: in the studies of spin glasses , much effort has been devoted either exprimentally or theoretically to the properties under magnetic fields . unfortunately , our understanding of them still has remained unsatisfactory@xcite . on theoretical side , most of the numerical studies have focused on the properties of the simple ising model , especially the three - dimensional ( 3d ) edwards - anderson ( ea ) model . while the existence of a true thermodynamic spin - glass ( sg ) transition has been established for this model in zero field , the question of its existence or nonexistence in magnetic fields has remained unsettled . this question is closely related to the hotly debated issue of whether the ordered state of the 3d ising sg in zero field exhibits a replica - symmetry breaking ( rsb ) or not .. Please generate the next two sentences of the article

if one tries to understand real experimental sg ordering , one has to remember that many of real sg materials are more or less heisenberg - like rather than ising , in the sense that the random magnetic anisotropy is considerably weaker than the isotropic exchange interaction@xcite . for example , in widely studied canonical spin glasses , _

Suppose that you have an abstract for a scientific paper: we present a method for rejecting competing models from noisy time - course data that does not rely on parameter inference . first we characterize ordinary differential equation models in only measurable variables using differential algebra elimination . next we extract additional information from the given data using gaussian process regression ( gpr ) and then transform the differential invariants . we develop a test using linear algebra and statistics to reject transformed models with the given data in a parameter - free manner . this algorithm exploits the information about transients that is encoded in the model s structure . we demonstrate the power of this approach by discriminating between different models from mathematical biology . keywords : model selection , differential algebra , algebraic statistics , mathematical biology . And you have already written the first three sentences of the full article: given competing mathematical models to describe a process , we wish to know whether our data is compatible with the candidate models . often comparing models requires optimization and fitting time course data to estimate parameter values and then applying an information criterion to select a ` best ' model @xcite . however sometimes it is not feasible to estimate the value of these unknown parameters ( e.g. large parameter space , nonlinear objective function , nonidentifiable etc ) . the parameter problem has motivated the growth of fields that embrace a parameter - free flavour such as chemical reaction network theory and stoichiometric theory @xcite .. Please generate the next two sentences of the article

however many of these approaches are limited to comparing the behavior of models at steady - state @xcite . inspired by techniques commonly used in applied algebraic geometry @xcite and algebraic statistics @xcite , methods for discriminating between models without estimating parameters has been developed for steady - state data @xcite , applied to models in wnt signaling @xcite , and then generalized to only include one data point @xcite .

Suppose that you have an abstract for a scientific paper: using a high resolution hydrodynamical cosmological simulation of the formation of a massive spheroidal galaxy we show that elliptical galaxies can be very compact and massive at high redshift in agreement with recent observations . accretion of stripped in - falling stellar material increases the size of the system with time and the central concentration is reduced by dynamical friction of the surviving stellar cores . in a specific case of a spheroidal galaxy with a final stellar mass of @xmath0 we find that the effective radius @xmath1 increases from @xmath2 at z = 3 to @xmath3 at z = 0 with a concomitant decrease in the effective density of an order of magnitude and a decrease of the central velocity dispersion by approximately 20% over this time interval . a simple argument based on the virial theorem shows that during the accretion of weakly bound material ( minor mergers ) the radius can increase as the square of the mass in contrast to the usual linear rate of increase for major mergers . by undergoing minor mergers compact high redshift spheroids can evolve into present - day systems with sizes and concentrations similar to observed local ellipticals . this indicates that minor mergers may be the main driver for the late evolution of sizes and densities of early - type galaxies . . And you have already written the first three sentences of the full article: there is recent observational evidence that a significant fraction of massive evolved spheroidal stellar systems is already in place at redshift @xmath4 . however , only a small percentage of these galaxies is fully assembled @xcite . the galaxies are smaller by a factor of three to five compared to present - day ellipticals at similar masses .. Please generate the next two sentences of the article

their effective stellar mass densities are at least one order of magnitude higher @xcite with significantly higher surface brightnesses compared to their low redshift analogs . these observations are difficult to reconcile with some current idealized formation scenarios for elliptical galaxies .

Suppose that you have an abstract for a scientific paper: the reaction @xmath0 was measured at the mainz microtron mami at an invariant mass of @xmath1 and four - momentum transfers of @xmath2 , @xmath3 and @xmath4 . for each value of @xmath5 , a rosenbluth separation of the transverse and longitudinal cross sections was performed . an effective lagrangian model was used to extract the ` axial mass ' from experimental data . we find a value of @xmath6 which is @xmath7 larger than the axial mass known from neutrino scattering experiments . this is consistent with recent calculations in chiral perturbation theory . , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , and _ pacs : _ 13.60.le , 25.30.rw , 14.20.dh _ keywords : _ nucleon axial form factor , coincident pion electroproduction . And you have already written the first three sentences of the full article: there are basically two methods to determine the weak axial form factor of the nucleon . one set of experimental data comes from measurements of ( quasi)elastic ( anti)neutrino scattering on protons @xcite , deuterons @xcite and other nuclei ( al , fe ) @xcite or composite targets like freon @xcite and propane @xcite . in the ( quasi)elastic picture of ( anti)neutrino - nucleus scattering , the @xmath8 weak transition amplitude can be expressed in terms of the nucleon electromagnetic form factors @xmath9 and @xmath10 and the axial form factor @xmath11 .. Please generate the next two sentences of the article

the axial form factor is then extracted by fitting the @xmath5-dependence of the ( anti)neutrino - nucleon cross section , @xmath12 in which @xmath13 is contained in the bilinear forms @xmath14 , @xmath15 and @xmath16 of the relevant form factors and is assumed to be the only unknown quantity . it can be parameterised in terms of an ` axial mass ' @xmath17 as @xmath18 . as extracted from ( quasi)elastic neutrino and antineutrino scattering experiments .

Suppose that you have an abstract for a scientific paper: previous studies have shown that _ wise_-selected hyperluminous , hot dust - obscured galaxies ( hot dogs ) are powered by highly dust - obscured , possibly compton - thick agns . high obscuration provides us a good chance to study the host morphology of the most luminous agns directly . we analyze the host morphology of 18 hot dogs at @xmath0 using hubble space telescope / wfc3 imaging . we find that hot dogs have a high merger fraction ( @xmath1 ) . by fitting the surface brightness profiles , we find that the distribution of srsic indices in our hot dog sample peaks around 2 , which suggests that most of hot dogs have transforming morphologies . we also derive the agn bolometric luminosity ( @xmath2 ) of our hot dog sample by using ir seds decomposition . the derived merger fraction and agn bolometric luminosity relation is well consistent with the variability - based model prediction @xcite . both the high merger fraction in ir - luminous agn sample and relatively low merger fraction in uv / optical - selected , unobscured agn sample can be expected in the merger - driven evolutionary model . finally , we conclude that hot dogs are merger - driven and may represent a transit phase during the evolution of massive galaxies , transforming from the dusty starburst dominated phase to the unobscured qso phase . . And you have already written the first three sentences of the full article: both cosmic star formation rate and active galactic nucleus ( agn ) density have been found to reach their peaks at @xmath32 @xcite . in the local universe , a supermassive black hole ( smbh ) generically exists in the center of early - type galaxies with the black hole mass tightly correlating with that of the galaxy s stellar bulge @xcite . the connection and co - evolution between the central smbh and host galaxy have therefore been suggested @xcite . in one of the most popular co - evolution scenarios ,. Please generate the next two sentences of the article

galaxy mergers have been proposed to funnel gas into the center of galaxies , leading to a central starburst and rapid growth of a smbh @xcite . one promising approach to investigate the merger - driven co - evolution scenario is to study the merger features in agn host galaxies . however , previous studies have produced mixed results .

Suppose that you have an abstract for a scientific paper: adequate description of electro and gamma nuclear physics is of utmost importance in studies of electron beam - dumps and intense electron beam accelerators . i also is mandatory to describe neutron backgrounds and activation in linear colliders . this physics was elaborated in geant4 over the last year , and now entered into the stage of practical application . in the geant4 photo - nuclear data base there are at present about 50 nuclei for which the photo - nuclear absorption cross sections have been measured . of these , data on 14 nuclei are used to parametrize the gamma nuclear reaction cross - section the resulting cross section is a complex , factorized function of @xmath0 and @xmath1 , where @xmath2 is the energy of the incident photon . electro - nuclear reactions are so closely connected with photo - nuclear reactions that sometimes they are often called `` photo - nuclear '' . the one - photon exchange mechanism dominates in electro - nuclear reactions , and the electron can be substituted by a flux of photons . folding this flux with the gamma - nuclear cross - section , we arrive at an acceptable description of the electro - nuclear physics . final states in gamma and electro nuclear physics are described using chiral invariant phase - space decay at low gamma or equivalent photon energies , and quark gluon string model at high energies . we will present the modeling of this physics in geant4 , and show results from practical applications . . And you have already written the first three sentences of the full article: the photo - nuclear cross sections parameterized in the geant4 covers all incident photon energies from hadron production threshold up - wards . the parameterization is subdivided into five energy regions , each corresponding to the physical process that dominates . these are the giant dipole resonance ( gdr ) region , the `` quasi - deuteron '' region , the @xmath3 isobar region characterized by the dominant peak in the cross section which extends from the pion threshold to 450 mev , the roper resonance region that extends from roughly 450 mev to 1.2 gev , and the reggeon - pomeron region above 1.2 gev . from the geant4@xcite photo - nuclear data base. Please generate the next two sentences of the article

currently 14 nuclei are used in defining the parameterization : @xmath4h , @xmath5h , @xmath6he , @xmath7li , @xmath8li , @xmath9be , @xmath10c , @xmath11o , @xmath12al , @xmath13ca , cu , sn , pb , and u. the result is a function of @xmath0 and @xmath1 , where @xmath2 is the incident photon energy . the cross - section is the sum of the components which parameterize each energy region .

Suppose that you have an abstract for a scientific paper: the attenuation of heavy - flavored particles in nucleus nucleus collisions tests the microscopic dynamics of medium - induced parton energy loss and , in particular , its expected dependence on the identity ( color charge and mass ) of the parent parton . we discuss the comparison of theoretical calculations with recent single - electron data from rhic experiments . then , we present predictions for the heavy - to - light ratios of @xmath0 and @xmath1 mesons at lhc energy . address = universit degli studi di padova and infn , padova , italy address = dep . de fsica de partculas and igfae , universidade de santiago de compostela , spain address = lpthe , universit pierre et marie curie ( paris 6 ) , france address = department of physics , cern , theory division , genve , switzerland address = department of physics and astronomy , university of stony brook , ny , usa . And you have already written the first three sentences of the full article: believed to be the main origin of the jet quenching phenomena observed @xcite in nucleus nucleus collisions at rhic energy @xmath2@xmath3 , parton energy loss via gluon - radiation is expected to depend on the properties ( gluon density and volume ) of the ` medium ' formed in the collision and on the properties ( color charge and mass ) of the ` probe ' parton @xcite . hard gluons would lose more energy than hard quarks due to the stronger color coupling with the medium .. Please generate the next two sentences of the article

in addition , charm and beauty quarks are qualitatively different probes with respect to light partons , since their energy loss is expected to be reduced , as a consequence of a mass - dependent restriction in the phase - space into which gluon radiation can occur @xcite . we study quenching effects for heavy quarks by supplementing perturbative qcd calculations of the baseline @xmath4 distributions with in - medium energy loss , included via the bdmps quenching weights .

Suppose that you have an abstract for a scientific paper: monte carlo simulations using the newly proposed wang - landau algorithm together with the broad histogram relation are performed to study the antiferromagnetic six - state clock model on the triangular lattice , which is fully frustrated . we confirm the existence of the magnetic ordering belonging to the kosterlitz - thouless ( kt ) type phase transition followed by the chiral ordering which occurs at slightly higher temperature . we also observe the lower temperature phase transition of kt type due to the discrete symmetry of the clock model . by using finite - size scaling analysis , the higher kt temperature @xmath0 and the chiral critical temperature @xmath1 are respectively estimated as @xmath2 and @xmath3 . the results are in favor of the double transition scenario . the lower kt temperature is estimated as @xmath4 . two decay exponents of kt transitions corresponding to higher and lower temperatures are respectively estimated as @xmath5 and @xmath6 , which suggests that the exponents associated with the kt transitions are universal even for the frustrated model . . And you have already written the first three sentences of the full article: frustration is one of the interesting subjects in statistical physics , mainly because it can induce additional symmetry and lead the system to display rich low - temperature structures . the so - called two - dimensional ( 2d ) fully frustrated xy models have attracted an extensive investigation in the last two decades @xcite . due to the frustration the systems possess additional discrete reflection symmetry @xmath7 , apart from the global spin rotation symmetry @xmath8 . the breakdown of these symmetries are the onset of two types of phase transitions , namely one corresponding to the magnetic transition of kosterlitz - thouless ( kt ) type @xcite and the other to the chiral transition . whether these transitions are decoupled or occur at the same temperature has long been a controversy @xcite .. Please generate the next two sentences of the article

another debated issue is whether the universality class of the chiral ordering belongs to the ising universality class or not @xcite . the system has a corresponding physical realization on a planar arrays of coupled josephson junctions in a transverse magnetic field @xcite and discotic liquid crystals @xcite . as a 2d frustrated xy system ,

Suppose that you have an abstract for a scientific paper: we show how the standard ( strmer - verlet ) splitting method for differential equations of hamiltonian mechanics ( with accuracy of order @xmath0 for a timestep of length @xmath1 ) can be improved in a systematic manner without using the composition method . we give the explicit expressions which increase the accuracy to order @xmath2 , and demonstrate that the method work on a simple anharmonic oscillator . splitting - method , hamilton - equations , higher - order - accuracy , symplecticity . And you have already written the first three sentences of the full article: hamilton equations of motion constitute a system of ordinary first order differential equations , @xmath3 where the @xmath4 denotes differentiation with respect to time @xmath5 , and @xmath6 . they can be viewed as the characteristic equations of the partial differential equation @xmath7 with @xmath8 the first order differential operator @xmath9 generating a flow on phase space . if @xmath10 does not depend explicitly on @xmath5 , a formal solution of ( [ hamiltonianflow ] ) is @xmath11 in most cases this expression remain just formal , but one may often split the hamiltonian into two parts , @xmath12 , with a corresponding splitting @xmath13 such that the flows generated by @xmath14 and @xmath15 separately are integrable .. Please generate the next two sentences of the article

one may then use the cambell - baker - hausdorff formula to approximate the flow generated by @xmath8 . one obtains the strang splitting formula @xcite @xmath16\right]+\cdots},\ ] ] which shows that time stepping this expression with a timestep @xmath1 provides an approximation with relative accuracy of order @xmath0 , exactly preserving the symplectic property of the flow .

Suppose that you have an abstract for a scientific paper: single photon sources based on semiconductor quantum dots offer distinct advantages for quantum information , including a scalable solid - state platform , ultrabrightness , and interconnectivity with matter qubits . a key prerequisite for their use in optical quantum computing and solid - state networks is a high level of efficiency and indistinguishability . pulsed resonance fluorescence ( rf ) has been anticipated as the optimum condition for the deterministic generation of high - quality photons with vanishing effects of dephasing . here , we generate pulsed rf single photons on demand from a single , microcavity - embedded quantum dot under _ s_-shell excitation with 3-ps laser pulses . the @xmath0-pulse excited rf photons have less than 0.3@xmath1 background contributions and a vanishing two - photon emission probability . non - postselective hong - ou - mandel interference between two successively emitted photons is observed with a visibility of 0.97(2 ) , comparable to trapped atoms and ions . two single photons are further used to implement a high - fidelity quantum controlled - not gate . single photons have been proposed as promising quantum bits ( qubits ) for quantum communication @xcite , linear optical quantum computing @xcite and as messengers in quantum networks @xcite . these proposals primarily rely upon a high degree of indistinguishability between individual photons to obtain the hong - ou - mandel ( hom ) type interference @xcite which is at the heart of photonic controlled logic gates and photon - interference - mediated quantum networking @xcite . among different types of single - photon emitters @xcite , quantum dots ( qds ) are attractive solid - state devices since they can be embedded in high - quality nanostructure cavities and waveguides to generate ultra - bright sources of single and entangled photons @xcite . qds also provide a light - matter interface @xcite and can in principle be scaled to large quantum networks @xcite . two - photon hom.... And you have already written the first three sentences of the full article: in our experiment , we begin with an optical characterization of the qds and observe a significantly reduced spectral linewidth of the emitted photons from a resonantly driven single qd compared with incoherent excitation methods including via above - bandgap and p - shell using cw lasers . figure@xmath3s2(a - c ) present a direct comparison of the spectral linewidth of the emitted photons from a single qd ( qd2 ) neutral exciton for different cw - laser excitation methods . at moderate power regime ( around saturation ) , the cw photoluminescence spectra arising from above band - gap and _ p_-shell excitation yields a linewidth of @xmath52.5ghz ( see fig.@xmath3s2a ) and @xmath51.5ghz ( fig.@xmath3s2b ) , respectively . on the other hand , cw rf photons ( see fig.@xmath3s2c ) exhibit a significantly narrower linewidth of @xmath50.48ghz even at high power regime well above saturation ( 32@xmath46 ) where a mollow triplet arises @xcite . figure@xmath3s2d shows a series of cw rf spectra at different laser power .. Please generate the next two sentences of the article

the coherence time @xmath47 fitted ( using the corrected eqn.(1 ) from ref.@xcite ) from the cw rf spectra at @xmath46 is closest to being radiative lifetime limited : @xmath47/@xmath48=0.93(6 ) , where @xmath49 is the exciton lifetime which is measured separately to be of 390(10)ps using time - resolved pulsed rf . this is consistent with the prediction that the pure _ s_-shell resonant excitation can eliminate dephasings associated with the incoherent excitation methods @xcite .

Suppose that you have an abstract for a scientific paper: we propose a technique to prepare coherent superpositions of two nondegenerate quantum states in a three - state ladder system , driven by two simultaneous fields near resonance with an intermediate state . the technique , of potential application to enhancement of nonlinear processes , uses adiabatic passage assisted by dynamic stark shifts induced by a third laser field . the method offers significant advantages over alternative techniques : ( i ) it does not require laser pulses of specific shape and duration and ( ) it requires less intense fields than schemes based on two - photon excitation with non - resonant intermediate states . we discuss possible experimental implementation for enhancement of frequency conversion in mercury atoms . . And you have already written the first three sentences of the full article: efficient mechanisms to generate coherent superpositions of quantum states are central to a rich variety of applications in modern quantum physics . quantum logic gates , i.e. the key components of a quantum computer @xcite , rely on superpositions of two degenerate quantum states as qubits @xcite . quantum tunnelling and localization in a double well potential can be controlled @xcite by techniques that require preparation of coherent superpositions .. Please generate the next two sentences of the article

numerous authors have noted that nonlinear optical processes , e.g. resonantly enhanced frequency mixing in atomic vapours , can be significantly improved @xcite by preparing the nonlinear optical medium in a coherent superposition of nondegenerate quantum states . whereas numerous techniques exist to prepare coherent superpositions of degenerate states , as needed for qubits in quantum computing , nonlinear optics still hold challenges .

Suppose that you have an abstract for a scientific paper: we present a theoretical analysis of intraband optical transitions from the intermediate pseudo - band of confined states to the conduction band in a finite , inhomogeneous stack of self - assembled semiconductor quantum dots . the chain is modeled with an effective hamiltonian including nearest - neighbor tunnel couplings and the absorption under illumination with both coherent ( laser ) and thermal radiation is discussed . we show that the absorption spectrum already for a few coupled dots differs from that of a single dot and develops a structure with additional maxima at higher energies . we find out that this leads to an enhancement of the overall transition rate under solar illumination by up to several per cent which grows with the number of qds but saturates already for a few qds in the chain . the decisive role of the strength of inter - dot coupling for the stability of this enhancement against qd stack inhomogeneity and temperature is revealed . one of the ways to improve the efficiency of solar cells is to introduce an intermediate band in the energy spectrum of a photovoltaic structure @xcite . in this way , electrons can be sequentially promoted from the valence band to the intermediate band and then to the conduction band by absorbing photons with energies below the band gap which are not converted into useful electrochemical energy in a standard structure . as an implementation of this concept , a stack of quantum dots ( qds ) in the intrinsic region of a p - i - n junction solar cell has been proposed @xcite . this idea has indeed gained some experimental support in recent years @xcite . quantum - dot - embedded p - i - n solar cells show higher quantum efficiency in near infrared range but their overall efficiency still is lower than the efficiency of similar devices without qds @xcite . on the theory side , models involving a single qd were formulated to describe the kinetics of transitions from and into the intermediate levels @xcite . on the other hand , modeling.... And you have already written the first three sentences of the full article: we are interested in the transitions from a single - electron bound state @xmath0 ( with a wave function @xmath1 and energy @xmath2 ) to a continuum state @xmath3 ( with a wave function @xmath4 and energy @xmath5 ) ( fig . [ fig : sketch ] ) . ( a ) sketch of a qd chain , ( b ) energy diagram of a qd chain with an electron transition from the bound state @xmath6 in the intermediate band to the state @xmath3 in the conduction band .. Please generate the next two sentences of the article

, width=321 ] we model the confined electron states @xmath0 as superpositions of the ground states @xmath7 confined in the individual dots ( where @xmath8 numbers the dots ) . for simplicity , we assume that each of these single dot states has an identical wave function , @xmath9 where @xmath10 is the position of the @xmath8th dot ( we assume that the dots are stacked along the growth direction @xmath11 ) . the ground state electron energies in the dots , @xmath12 , may differ .

Suppose that you have an abstract for a scientific paper: in this paper , we consider phenomenology of a model with an @xmath0 gauge symmetry . since the muon couples to the @xmath0 gauge boson ( called @xmath1 boson ) , its contribution to the muon anomalous magnetic moment ( muon g-2 ) can account for the discrepancy between the standard model prediction and the experimental measurements . on the other hand , the @xmath1 boson does not interact with the electron and quarks , and hence there are no strong constraints from collider experiments even if the @xmath1 boson mass is of the order of the electroweak scale . we show an allowed region of a parameter space in the @xmath0 symmetric model , taking into account consistency with the electroweak precision measurements as well as the muon g-2 . we study the large hadron collider ( lhc ) phenomenology , and show that the current and future data would probe the interesting parameter space for this model . # 1 .75 in * muon g-2 and lhc phenomenology in the @xmath0 gauge symmetric model * .75 in keisuke harigaya@xmath2 , takafumi igari@xmath3 , mihoko m. nojiri@xmath4 , + michihisa takeuchi@xmath5 , and kazuhiro tobe@xmath6 0.25 in _ @xmath2kavli ipmu ( wpi ) , todias , university of tokyo , chiba , kashiwa , 277 - 8583 , japan _ _ @xmath3department of physics , nagoya university , aichi , nagoya 464 - 8602 , japan _ _ @xmath7theory center , kek , tsukuba , ibaraki 305 - 0801 , japan _ _ @xmath5theoretical particle physics and cosmology group , department of physics , king s college london , london wc2r 2ls , uk _ _ @xmath8kobayashi - maskawa institute for the origin of particles and the universe , + nagoya university , aichi , nagoya 464 - 8602 , japan _ .5 in kcl - ph - th/2013-*37 * kek - th-1684 ipmu 13 - 0213 . And you have already written the first three sentences of the full article: the standard model of elementary particles ( sm ) has been very successful in describing the nature at the electroweak ( ew ) scale . recently , the atlas and cms collaborations at the large hadron collider ( lhc ) have discovered a new particle @xcite , which is consistent with the sm higgs boson . this discovery also strengthens the correctness of the sm .. Please generate the next two sentences of the article

so far , no explicit evidence of physics beyond the sm has been reported from the lhc . several groups , however , have reported an anomaly of the muon anomalous magnetic moment @xmath9 ( muon g-2 ) , which has been precisely measured experimentally @xcite and compared with state - of - the - art theoretical predictions ( for example , see @xcite and references therein ) .

Suppose that you have an abstract for a scientific paper: a smooth five - dimensional @xmath0-cobordism becomes a smooth product if stabilized by a finite number @xmath1 of @xmath2)$ ] s . we show that for amenable fundamental groups , the minimal @xmath1 is subextensive in covers , i.e. , @xmath3 . we focus on the notion of sweepout width , which is a bridge between @xmath4-dimensional topology and coarse geometry . . And you have already written the first three sentences of the full article: let @xmath5 is an @xmath0-cobordism between smooth manifolds @xmath6 and @xmath7 . since pioneering work in the 1980 s it has been known that @xmath6 and @xmath7 are not necessarily diffeomorphic @xcite , but they are homeomorphic @xcite when the fundamental group is of a certain type , called `` good '' ( a kind of time - dependent definition ) by practitioners . good groups @xcite were built from the class of polynomial growth groups and later the more general subexponential class by closure under four operations : extension , quotient , direct limit , and subgroup .. Please generate the next two sentences of the article

it is tempting to guess that good groups can be extended to all amenable groups , but this is not presently known . though the question of any classification up to diffeomorphism seems completely intractable at this point , it was noticed by quinn @xcite in the 1970 s that these subtleties disappear under stabilization . that is , there exists a natural number @xmath1 so that @xmath8 is a product cobordism , where for a @xmath4-manifold @xmath6 ( or @xmath7 ) @xmath9 and for a @xmath10-dimensional cobordism @xmath5 , @xmath11 denotes the `` connected sum @xmath12 $ ] '' with @xmath13 summed parametrically along a vertical arc in @xmath5 . for the remainder of the paper

Suppose that you have an abstract for a scientific paper: we report a detailed nuclear magnetic resonance ( nmr ) study by combined @xmath0na and @xmath1as measurements over a broad range of doping to map the phase diagram of nafe@xmath2co@xmath3as . in the underdoped regime ( @xmath4 0.017 ) , we find a magnetic phase with robust antiferromagnetic ( afm ) order , which we denote the _ s_-afm phase , cohabiting with a phase of weak and possibly proximity - induced afm order ( _ w_-afm ) whose volume fraction @xmath5% is approximately constant . near optimal doping , at @xmath6 , we observe a phase separation between static antiferromagnetism related to the _ s_-afm phase and a paramagnetic ( pm ) phase related to _ w_-afm . the volume fraction of afm phase increases upon cooling , but both the nel temperature and the volume fraction can be suppressed systematically by applying a @xmath7-axis magnetic field . on cooling below @xmath8 , superconductivity occupies the pm region and its volume fraction grows at the expense of the afm phase , demonstrating a phase separation of the two types of order based on volume exclusion . at higher dopings , static antiferromagnetism and even critical afm fluctuations are completely suppressed by superconductivity . thus the phase diagram we establish contains two distinct types of phase separation and reflects a strong competition between afm and superconducting phases both in real space and in momentum space . we suggest that both this strict mutual exclusion and the robustness of superconductivity against magnetism are consequences of the extreme two - dimensionality of nafeas . . And you have already written the first three sentences of the full article: competing electronic phases underlie a number of the most unconventional phenomena in condensed matter systems . when this competition is sufficiently strong , the usual outcome is a phase separation . one outstanding example of this situation is provided by materials showing colossal magnetoresistance , where competing magnetic interactions lead to phase separation between conducting ferromagnetic and insulating antiferromagnetic ( afm ) regions @xcite . as a consequence , an external magnetic field can be used to control the resistance over many orders of magnitude , offering possible applications in electronic devices . in cuprate superconductors ,. Please generate the next two sentences of the article

the competition between antiferromagnetism and superconductivity forms the basis for the majority of the observed phenomena and for several classes of materials the debate can be phrased in terms of the extent to which phase separation is the outcome . the stripe phase , which has been the object of heated research interest for two decades , can be considered as a form of atomic - scale phase separation between afm and superconducting ( sc ) regions , and such self - organizing heterostructures are a direct reflection of the electronic correlations whose effects are essential to understanding the mechanism of high - temperature superconductivity @xcite . the competition between afm and sc phases also forms the foundation for the physics of iron - based superconductors @xcite , where it is manifest in the emergence of a tetragonal sc phase upon doping- or pressure - induced suppression of an orthorhombic afm phase .

Suppose that you have an abstract for a scientific paper: the basic ideas underlying the production dynamics and search techniques for disoriented chiral condensate are described . . And you have already written the first three sentences of the full article: these notes are an abbreviated version of lectures given at the 1997 zakopane school . they contain two topics . the first is a description in elementary terms of the basic ideas underlying the speculative hypothesis that pieces of strong - interaction vacuum with a rotated chiral order parameter , disoriented chiral condensate or dcc , might be produced in high energy elementary particle collisions .. Please generate the next two sentences of the article

the second topic is a discussion of the phenomenological techniques which may be applied to data in order to experimentally search for the existence of dcc . two other topics were discussed in the lectures but will not be mentioned in these notes other than in this introduction .

Suppose that you have an abstract for a scientific paper: several high - performance lab instruments suitable for manual assembly have been developed using low - pin - count 32-bit microcontrollers that communicate with an android tablet via a usb interface . a single android tablet app accommodates multiple interface needs by uploading parameter lists and graphical data from the microcontrollers , which are themselves programmed with easily - modified c code . the hardware design of the instruments emphasizes low chip counts and is highly modular , relying on small daughter boards `` for special functions such as usb power management , waveform generation , and phase - sensitive signal detection . in one example , a daughter board provides a complete waveform generator and direct digital synthesizer that fits on a 1.5''@xmath00.8 " circuit card . . And you have already written the first three sentences of the full article: in 2011 , i described a timing sequencer and related laser lab instrumentation based on 16-bit microcontrollers and a homemade custom keypad / display unit.@xcite since then , two new developments have enabled a far more powerful approach : the availability of high - performance 32-bit microcontrollers in low - pin - count packages suitable for hand assembly , and the near - ubiquitous availability of tablets with high - resolution touch - screen interfaces and open development platforms . this article describes several new instrument designs tailored for research in atomic physics and laser spectroscopy . each utilizes a 32-bit microcontroller in conjunction with a usb interface to an android tablet , which serves as an interactive user interface and graphical display .. Please generate the next two sentences of the article

these instruments are suitable for construction by students with some experience in soldering small chips , and are programmed using standard c code that can easily be modified . this offers both flexibility and educational opportunities .

Suppose that you have an abstract for a scientific paper: we study the entanglement dynamics of two qubits , each of which is embedded into its local amplitude - damping reservoir , and the entanglement distribution among all the bipartite subsystems including qubit - qubit , qubit - reservoir , and reservoir - reservoir . it is found that the entanglement can be stably distributed among all components , which is much different to the result obtained under the born - markovian approximation by c. e. lpez _ et al . _ [ phys . rev . lett . * 101 * , 080503 ( 2008 ) ] , and particularly it also satisfies an identity . our unified treatment includes the previous results as special cases . the result may give help to understand the physical nature of entanglement under decoherence . . And you have already written the first three sentences of the full article: entanglement in quantum multipartite systems is a unique property in quantum world . it plays an important role in quantum information processing @xcite . therefore , the study of its essential features and dynamical behavior under the ubiquitous decoherence of relevant quantum system has attracted much attention in recent years @xcite .. Please generate the next two sentences of the article

for example , it was found that the entanglement of qubits under the markovian decoherence can be terminated in a finite time despite the coherence of single qubit losing in an asymptotical manner @xcite . the phenomenon called as entanglement sudden death ( esd ) @xcite has been observed experimentally @xcite .

Suppose that you have an abstract for a scientific paper: the rosette hh1 jet is a collimated flow immersed in the strong uv radiation field of the rosette nebula . we investigate the physical properties of the rosette hh1 jet using high - quality narrow - band images and high - dispersion spectroscopy . the new images show that the axis of the jet is not precisely aligned with the star near the base of the jet . the high resolution of the spectra allows us to accurately determine the contributions from the region , jet , and star . the appoaching and receding sides of the expanding shell of the rosette nebula are at heliocentric velocities of 13 and 40 km s@xmath0 , while the jet reaches a maximum velocity offset at a heliocentric velocity of @xmath130 km s@xmath0 . the [ ] doublet ratios indicate an electron density of @xmath21000 @xmath3 in the jet and @xmath4100 @xmath3 in the region . with a careful subtraction of the nebular and jet components , we find the stellar h@xmath5 line is dominated by a broad absorption profile with little or no emission component , indicating a lack of substantial circumstellar material . the circumstellar material has most likely been photo - evaporated by the strong uv radiation field in the rosette nebula . the evaporation time scale is 10@xmath6 10@xmath7 yr . the rosette hh1 jet source provides evidence for an accelerated evolution from a ctts to a wtts due to the strong uv radiation field ; therefore , both cttss and wttss can be spatially mixed in regions with massive star formation . . And you have already written the first three sentences of the full article: herbig - haro ( hh ) objects immersed in an ultraviolet ( uv ) radiation field can be photoionized externally @xcite . the photoionized jets / outflows of hh objects become optically visible , and thus their detailed physical properties can be studied . such photoionized hh jet systems have been identified in the orion nebula and in the reflection nebula ngc 1333 @xcite .. Please generate the next two sentences of the article

recently , two such photoionized jet systems , the rosette hh1 and hh2 jets , were discovered within the central cavity of the rosette nebula @xcite . the rosette nebula is a spectacular region excavated by strong stellar winds from dozens of ob stars at the center of the young open cluster ngc 2244 , the primary component of a possible twin cluster recently identified using the 2mass ( two micron all sky survey ) database @xcite . at a distance of @xmath2 1.39 kpc @xcite , this emerging young open cluster is found to have a main sequence turn - off age of about 1.9 myr @xcite .

Suppose that you have an abstract for a scientific paper: we report a detection of the excited @xmath0 rotational transition of para- in apm 08279 + 5255 using the iram plateau de bure interferometer . at @xmath1 , this is the highest - redshift detection of interstellar water to date . from lvg modeling , we conclude that this transition is predominantly radiatively pumped and on its own does not provide a good estimate of the water abundance . however , additional water transitions are predicted to be detectable in this source , which would lead to an improved excitation model . we also present a sensitive upper limit for the hf @xmath2 absorption toward apm 08279 + 5255 . while the face - on geometry of this source is not favorable for absorption studies , the lack of hf absorption is still puzzling and may be indicative of a lower fluorine abundance at @xmath1 compared with the galactic ism . . And you have already written the first three sentences of the full article: molecules such as co or hcn have been commonly used as tracers of molecular gas in high - redshift galaxies . however , recent observations with the _ herschel space observatory _ @xcite have shown strong spectroscopic signatures from other light hydrides , such as water , h@xmath3o@xmath4 , or hf , in nearby active galaxies ( e.g. , @xcite ) . these lines are blocked by the earth s atmosphere , but can be observed , redshifted , in distant galaxies using the current millimeter and submillimeter facilities .. Please generate the next two sentences of the article

for example , @xcite have recently reported a detection of water in j090302 - 014127b ( sdp.17b ) at @xmath5 . one of the exciting recent results from hifi @xcite is the detection of widespread absorption in the fundamental @xmath2 rotational transition of hydrogen fluoride toward galactic sources @xcite .

Suppose that you have an abstract for a scientific paper: a huge amount of entropy is produced at places where fresh water and seawater mix , for example at river mouths . this mixing process is a potentially enormous source of sustainable energy , provided it is harnessed properly , for instance by a cyclic charging and discharging process of porous electrodes immersed in salt and fresh water , respectively [ d. brogioli , phys . . lett . * 103 * , 058501 ( 2009 ) ] . here we employ a modified poisson - boltzmann free - energy density functional to calculate the ionic adsorption and desorption onto and from the charged electrodes , from which the electric work of a cycle is deduced . we propose optimal ( most efficient ) cycles for two given salt baths involving two canonical and two grand - canonical ( dis)charging paths , in analogy to the well - known carnot cycle for heat - to - work conversion from two heat baths involving two isothermal and two adiabatic paths . we also suggest a slightly modified cycle which can be applied in cases that the stream of fresh water is limited . + bob evans about water ( 1998 ) . + + bob evans about ionic criticality ( 1998 ) . . And you have already written the first three sentences of the full article: where river water meets the sea , an enormous amount of energy is dissipated as a result of the irreversible mixing of fresh and salt water . the dissipated energy is about 2 kj per liter of river water , _ i.e. _ equivalent to a waterfall of 200 m @xcite .. Please generate the next two sentences of the article

it is estimated that the combined power from all large estuaries in the world could take care of approximately 20% of today s worldwide energy demand @xcite . extracting or storing this energy is therefore a potentially serious option that our fossil - fuel burning society may have to embrace in order to become sustainable .

Suppose that you have an abstract for a scientific paper: using molecular dynamics based on langevin equations with a coordinate- and velocity - dependent damping coefficient , we study the frictional properties of a thin layer of `` soft '' lubricant ( where the interaction within the lubricant is weaker than the lubricant - substrate interaction ) confined between two solids . at low driving velocities the system demonstrates stick - slip motion . the lubricant may or may not be melted during sliding , thus exhibiting either the `` liquid sliding '' ( ls ) or the `` layer over layer sliding '' ( lols ) regimes . the lols regime mainly operates at low sliding velocities . we investigate the dependence of friction properties on the misfit angle between the sliding surfaces and calculate the distribution of static frictional thresholds for a contact of polycrystalline surfaces . . And you have already written the first three sentences of the full article: the problem of boundary lubrication is very interesting from the physical point of view and important for practical applications , but it is not fully understood yet @xcite . conventional lubricants belong to the type of liquid ( `` soft '' ) lubricants , where the amplitude of molecular interactions within the lubricant , @xmath0 , is smaller than the lubricant - substrate interaction , @xmath1 . due to strong coupling with the substrates , lubricant monolayers cover the surfaces , and protect them from wear .. Please generate the next two sentences of the article

a thin lubricant film , when its thickness is lower than about six molecular layers , typically solidifies even if the conditions ( temperature and pressure ) are those corresponding to the bulk liquid state . as a result , the static friction force is nonzero , @xmath2 , and the system exhibits stick - slip motion , when the top substrate is driven through an attached spring ( which also may model the slider elasticity ) . in detail , at the beginning of motion the spring elongates , the driving force increases till it reaches the static threshold @xmath3 . then a fast sliding event takes place , the spring relaxes , the surfaces stick again , and the whole process repeats itself .

Suppose that you have an abstract for a scientific paper: we consider in this paper blow - up solutions of the semilinear wave equation in one space dimension , with an exponential source term . assuming that initial data are in @xmath0 or some times in @xmath1 , we derive the blow - up rate near a non - characteristic point in the smaller space , and give some bounds near other points . our result generalize those proved by godin under high regularity assumptions on initial data . . And you have already written the first three sentences of the full article: we consider the one dimensional semilinear wave equation : @xmath2 where @xmath3 and @xmath4 . we may also add more restriction on initial data by assuming that @xmath5 the cauchy problem for equation ( [ waveq ] ) in the space @xmath6 follows from fixed point techniques ( see section [ cauchy - problem ] below ) . + if the solution is not global in time , we show in this paper that it blows up ( see theorems [ th ] and [ new ] below ) .. Please generate the next two sentences of the article

for that reason , we call it a blow - up solution . the existence of blow - up solutions is guaranteed by ode techniques and the finite speed of propagation .

Suppose that you have an abstract for a scientific paper: generalized vorobev - yablonski polynomials have been introduced by clarkson and mansfield in their study of rational solutions of the second painlev hierarchy . we present new hankel determinant identities for the squares of these special polynomials in terms of schur polynomials . as an application of the identities , we analyze the roots of generalized vorobev - yablonski polynomials and provide formul for the boundary curves of the highly regular patterns observed numerically in @xcite . . And you have already written the first three sentences of the full article: let @xmath0 denote a solution of the second painlev equation @xmath1 it is known that for special values of the parameter @xmath2 the equation admits rational solutions . in fact vorobev and yablonski @xcite showed that for @xmath3 , the equation has a unique rational solution of the form @xmath4 which is constructed in terms of the vorobev - yablonski polynomials @xmath5 . these special polynomials can be defined via a differential - difference equation @xmath6 where @xmath7 , or equivalently @xcite in determinantal form : with @xmath8 for @xmath9 , @xmath10_{\ell , j=0}^{n-1},\ \ n\in\mathbb{z}_{\geq 1};\ \ \ \ \ \sum_{k=0}^{\infty}q_k(x)w^k=\exp\left[-\frac{4}{3}w^3+wx\right].\ ] ] for our purposes , it will prove useful to rewrite in terms of schur polynomials . in general ( cf .. Please generate the next two sentences of the article

@xcite ) , the schur polynomial @xmath11 $ ] in the variable @xmath12 associated to the partition @xmath13 with @xmath14 is determined by the jacobi - trudi determinant , [ jtrudi ] s _ ( ) = _ j , k=1^ ( ) . here , @xmath15 for @xmath16 is defined by the generating series [ hdef ] _

Suppose that you have an abstract for a scientific paper: we consider a gaussian sequence space model @xmath0 where @xmath1 has a diagonal covariance matrix @xmath2 . we consider the situation where the parameter vector @xmath3 is sparse . our goal is to estimate the unknown parameter by a model selection approach . the heterogenous case is much more involved than the direct model . indeed , there is no more symmetry inside the stochastic process that one needs to control since each empirical coefficient has its own variance . the problem and the penalty do not only depend on the number of coefficients that one selects , but also on their position . this appears also in the minimax bounds where the worst coefficients will go to the larger variances . however , with a careful and explicit choice of the penalty we are able to select the correct coefficients and get a sharp non - asymptotic control of the risk of our procedure . some simulation results are provided . . And you have already written the first three sentences of the full article: we consider the following sequence space model @xmath4 where @xmath5 are the coefficients of a signal and the noise @xmath6 has a diagonal covariance matrix @xmath7 . this heterogeneous model may appear in several frameworks where the variance is fluctuating , for example in heterogeneous regression , coloured noise , fractional brownian motion models or statistical inverse problems , for which the general literature is quite exhaustive @xcite . the goal is to estimate the unknown parameter @xmath8 by using the observations @xmath9 .. Please generate the next two sentences of the article

model selection is a core problem in statistics . one of the main reference in the field dates back to the aic criterion @xcite , but there has been a huge amount of papers on this subject ( e.g. , @xcite ) .

Suppose that you have an abstract for a scientific paper: data obtained during five months of 2001 with the gravitational wave ( gw ) detectors explorer and nautilus were studied in correlation with the gamma ray burst data ( grb ) obtained with the bepposax satellite . during this period bepposax was the only grb satellite in operation , while explorer and nautilus were the only gw detectors in operation . no correlation between the gw data and the grb bursts was found . the analysis , performed over 47 grb s , excludes the presence of signals of amplitude @xmath0 , with 95% probability , if we allow a time delay between gw bursts and grb within @xmath1 s , and @xmath2 , if the time delay is within @xmath3 s. the result is also provided in form of scaled likelihood for unbiased interpretation and easier use for further analysis . _ @xmath4 istituto nazionale di fisica nucleare infn , rome _ + _ @xmath5 university of rome `` tor vergata '' and infn , rome 2 _ + _ @xmath6 ifsi - cnr and infn , rome _ + _ @xmath7 university of laquila and infn , rome 2 _ + _ @xmath8 iess - cnr and infn , rome _ + _ @xmath9 university of rome `` la sapienza '' and infn , rome _ + _ @xmath10 istituto nazionale di fisica nucleare infn , frascati _ + _ @xmath11 university of ferrara and iasf - cnr , bologna _ + _ @xmath12 university of ferrara , ferrara _ + _ @xmath13 university of ferrara , ferrara and ita `` i. calvi '' , finale emilia , modena _ + _ @xmath14 university of rome `` tor vergata '' and infn , frascati _ + _ @xmath15 ifsi - cnr and infn , rome 2 _ + _ @xmath16 ifsi - cnr and infn , frascati _ + + . And you have already written the first three sentences of the full article: one of the most important astrophysical phenomena still lacking an explanation is the origin of the celestial gamma - ray bursts ( grb ) . these are powerful flashes of gamma - rays lasting from less than one second to tens of seconds , with isotropic distribution in the sky . they are observed above the terrestrial atmosphere with x gamma ray detectors aboard satellites @xcite .. Please generate the next two sentences of the article

thanks to the bepposax satellite @xcite , afterglow emission at lower wavelengths has been discovered @xcite and we now know that at least long ( @xmath17s ) grb s are at cosmological distances , with measured red shifts up to 4.5 ( see , e.g. , review by djorgovski @xcite and references therein ) . among the possible explanations of these events , which involve huge energy releases ( up to @xmath18 erg , assuming isotropic emission ) , the most likely candidates are the collapse of a very massive star ( hypernova ) and the coalescence of one compact binary system ( see , e.g. , reviews by piran @xcite and mszros @xcite and references therein ) . in both cases emission of gravitational waves ( gw ) is expected to be associated with them ( e.g. ref . @xcite ) . according to several models , the duration of a gw burst is predicted to be of the order of a few milliseconds for a variety of sources , including the coalescing and merging black holes and/or neutron star binaries .

Suppose that you have an abstract for a scientific paper: a simple mathematical definition of the 4-port model for pure prolog is given . the model combines the intuition of ports with a compact representation of execution state . forward and backward derivation steps are possible . the model satisfies a modularity claim , making it suitable for formal reasoning . . And you have already written the first three sentences of the full article: in order to formally handle ( specify and prove ) some properties of prolog execution , we needed above all a definition of a port . a port is perhaps the single most popular notion in prolog debugging , but theoretically it appears still rather elusive . the notion stems from the seminal article of l.byrd @xcite which identifies four different types of control flow in a prolog execution , as movements in and out of procedure _ boxes _ via the four _ ports _ of these boxes : * _ call _ , entering the procedure in order to solve a goal , * _ exit _ , leaving the procedure after a success , i.e. a solution for the goal is found , * _ fail _ , leaving the procedure after the failure , i.e. there are no ( more ) solutions , * _ redo _ , re - entering the procedure , i.e. another solution is sought for . in this work , we present a formal definition of ports , which is a calculus of execution states , and hence provide a formal model of pure prolog execution , s : pp .. Please generate the next two sentences of the article

our approach is to define ports by virtue of their effect , as _ port transitions_. a port transition relates two _

Suppose that you have an abstract for a scientific paper: we present an analysis of the behaviour of the ` coarse - grained ' ( ` mesoscopic ' ) rank partitioning of the mean energy of collections of particles composing virialized dark matter halos in a @xmath0-cdm cosmological simulation . we find evidence that rank preservation depends on halo mass , in the sense that more massive halos show more rank preservation than less massive ones . we find that the most massive halos obey arnold s theorem ( on the ordering of the characteristic frequencies of the system ) more frequently than less massive halos . this method may be useful to evaluate the coarse - graining level ( minimum number of particles per energy cell ) necessary to reasonably measure signatures of ` mesoscopic ' rank orderings in a gravitational system . . And you have already written the first three sentences of the full article: dissipationless n - body simulations of stellar systems indicate that scaling relations such as the so - called ` fundamental plane ' ( hereon , fp ) , that is , the systematic deviation from the expectations of the virial theorem applied to these systems , could be reproduced from the final products of hierarchical merging of galactic model progenitors @xcite . however , not all evolutionary conditions lead to fp - like relations : simple gravitational collapses do not . that is , objects resulted from mergers form a slightly non - homologous family ( and a fp - like relation ) , whereas collapses are homologous among themselves ( and show no deviation from the virial expectations ; see @xcite ) . at the same time ,. Please generate the next two sentences of the article

kandrup and collaborators @xcite argued on the existence of ` mesoscopic constraints ' of pure gravitational origin in systems relaxing towards virialization ( hereon , the ` kandrup effect ' ) . these constraints were inferred from the general preservation of the ` coarse - grained ' partitioning of the ranked energy distribution of particles , and seemed to regulate somehow the gravitational evolution of these galaxy models towards equilibrium .

Suppose that you have an abstract for a scientific paper: the prediction of cross sections for nuclei far off stability is crucial in the field of nuclear astrophysics . in recent calculations the nuclear level density as an important ingredient to the statistical model ( hauser - feshbach ) has shown the highest uncertainties . we present a global parametrization of nuclear level densities within the back - shifted fermi - gas formalism . employment of an energy - dependent level density parameter @xmath0 , based on microscopic corrections from a recent frdm mass formula , and a backshift @xmath1 , based on pairing and shell corrections , leads to a highly improved fit of level densities at the neutron - separation energy in the mass range @xmath2 . the importance of using proper microscopic corrections from mass formulae is emphasized . the resulting level description is well suited for astrophysical applications . the level density can also provide clues to the applicability of the statistical model which is only correct for a high density of excited states . using the above description , one can derive a `` map '' for the applicability of the model to reactions of stable and unstable nuclei with neutral and charged particles . . And you have already written the first three sentences of the full article: explosive nuclear burning in astrophysical environments produces unstable nuclei , which again can be targets for subsequent reactions . in addition , it involves a very large number of stable nuclei , which are not fully explored by experiments . thus , it is necessary to be able to predict reaction cross sections and thermonuclear rates with the aid of theoretical models . explosive burning in supernovae involves in general intermediate mass and heavy nuclei . due to a large nucleon number. Please generate the next two sentences of the article

they have intrinsically a high density of excited states . a high level density in the compound nucleus at the appropriate excitation energy allows to make use of the statistical model approach for compound nuclear reactions ( e.g. @xcite ) , which averages over resonances . in this paper , we want to present new results obtained within this approach and outline in a clear way , where its application is valid .

Suppose that you have an abstract for a scientific paper: we introduce and solve a model which considers two coupled networks growing simultaneously . the dynamics of the networks is governed by the new arrival of network elements ( nodes ) making preferential attachments to pre - existing nodes in both networks . the model segregates the links in the networks as intra - links , cross - links and mix - links . the corresponding degree distributions of these links are found to be power - laws with exponents having coupled parameters for intra- and cross - links . in the weak coupling case the model reduces to a simple citation network . as for the strong coupling , it mimics the mechanism of _ the web of human sexual contacts_. . And you have already written the first three sentences of the full article: today , with a vast amount of publications being produced in every discipline of scientific research , it can be rather overwhelming to select a good quality work ; that is enriched with original ideas and relevant to scientific community . more often this type of publications are discovered through the citation mechanism . it is believed that an estimate measure for scientific credibility of a paper is the number of citations that it receives , though this should not be taken too literally since some publications may have gone unnoticed or have been forgotten about over time .. Please generate the next two sentences of the article

knowledge of how many times their publications are cited can be seen as good feedback for the authors , which brings about an unspoken demand for the statistical analysis of citation data . one of the impressive empirical studies on citation distribution of scientific publications @xcite showed that the distribution is a power - law form with exponent @xmath0 .

Suppose that you have an abstract for a scientific paper: we present optical spectroscopic identifications of hard x - ray ( 5 - 10 kev ) selected sources belonging to the hellas sample obtained with _ bepposax _ down to a 5 - 10 kev flux limit of @xmath0@xmath1@xmath2 erg @xmath3 s@xmath4 . the sample consists of 118 sources . 25 sources have been identified trough correlations with catalogues of known sources . 49 have been searched for spectroscopic identification at the telescope . 13 fields resulted empty down to r=21 . 37 sources have been identified with type 1 agn and 9 with type 2 agn . the remaining are : 5 narrow emission line galaxies , 6 clusters , 2 bl lac , 1 radio galaxy and 1 star . combining these objects with other hard x - ray selected agns from _ asca _ and _ heao1 _ , we find that the local luminosity function of type 1 agn in the 2 - 10 kev band is fairly well represented by a double - power - law - function . there is evidence for significant cosmological evolution according to a pure luminosity evolution ( ple ) model @xmath5@xmath6@xmath7 , with @xmath8=2.12 and @xmath8=2.22 ( @xmath9@xmath10@xmath11 ) in a ( @xmath12,@xmath13)=(1.0,0.0 ) and in a ( @xmath12,@xmath13)=(0.3,0.7 ) cosmology , respectively . the data show an excess of faint high redshift type 1 agn which is well modeled by a luminosity dependent density evolution ( ldde ) , similarly to what observed in the soft x - rays . however , in both cosmologies , the statistic is not significant enough to distinguish between the ple and ldde models . the fitted models imply a contribution of agn1 to the 2 - 10 kev x - ray background from 35% up to 60% . . And you have already written the first three sentences of the full article: agn have first been discovered in the radio and soon after searched in the optical band . consequently , they have been classified using their optical characteristics and mainly divided into two categories : type 1 ( agn1 ) and 2 ( agn2 ) according to the presence or not of broad emission lines in their optical spectra ( we will keep this definition of agn1 throughout this paper ) . before the advent of the last generation of hard x - ray telescopes , agn samples where predominantly based on agn1 selected either in the optical or , later on , in the soft x - rays by _ einstein _ and _ rosat_. in these bands. Please generate the next two sentences of the article

the evolution of agn1 has been well measured ( see e.g. della ceca et al . 1992 ; boyle et al . 2000 ; miyaji , hasinger , & schmidt 2000 ) . on the contrary the production of samples of agn2 has been difficult at any wavelength and limited to few local surveys .

Suppose that you have an abstract for a scientific paper: we develop the notion of shower partons and determine their distributions in jets in the framework of the recombination model . the shower parton distributions obtained render a good fit of the fragmentation functions . we then illustrate the usefulness of the distributions in a problem where a jet is produced in the environment of thermal partons as in heavy - ion collisions . the recombination of shower and thermal partons is shown to be more important than fragmentation . application to the study of two - particle correlation in a jet is also carried out . @xmath0 2@xmath1 . And you have already written the first three sentences of the full article: the theoretical description of hadron production at large transverse momentum ( @xmath2 ) in either hadronic or nuclear collisions at high energies is traditionally framed in a two - step process that involves first a hard scattering of partons , followed by the fragmentation of the scattered parton to the detected hadron @xcite . the first part is calculable in perturbation qcd , while the second part makes use of fragmentation functions that are determined phenomenologically . such a production mechanism has recently been found to be inadequate for the production of particles at intermediate @xmath2 in heavy - ion collisions @xcite . instead of fragmentation. Please generate the next two sentences of the article

it is the recombination of partons that is shown to be the more appropriate hadronization process , especially when the soft partons are involved . although at extremely high @xmath2 fragmentation is still dominant , it is desirable to have a universal description that can be applied to any @xmath2 , based on the same hadronization scheme . to achieve that goal

Suppose that you have an abstract for a scientific paper: the explosive transition of a massive neutron star to a quark star ( the quark - nova ; qn ) releases in excess of @xmath0 erg in kinetic energy which can drastically impact the surrounding environment of the qn . a qn is triggered when a neutron star gains enough mass to reach the critical value for quark deconfinement to happen in the core . in binaries , a neutron star has access to mass reservoirs ( e.g. accretion from a companion or from a common envelope ; ce ) . we explain observed light - curves of hydrogen - poor superluminous supernovae ( slsne ia ) in the context of a qn occurring in the second ce phase of a massive binary . in particular this model gives good fits to light - curves of slsne with double - humped light - curves . our model suggests the qn as a mechanism for ce ejection and that they be taken into account during binary evolution . in a short period binary with a white dwarf companion , the neutron star can quickly grow in mass and experience a qn event . part of the qn ejecta collides with the white dwarf ; shocking , compressing ; and heating it to driving a thermonuclear runaway producing a sn ia impostor ( a qn - ia ) . unlike `` normal '' type ia supernovae where no compact remnant is formed , a qn - ia produces a quark star undergoing rapid spin - down providing additional power along with the @xmath1ni decay energy . type ia sne are used as standard candles and contamination of this data by qne - ia can infer an incorrect cosmology . . And you have already written the first three sentences of the full article: a qn is the explosive transition of a massive neutron star ( ns ) to a quark star ( qs ; the compact remnant ) . it ejects the outermost layers of the ns as the relativistic qn ejecta with kinetic energy exceeding excess @xmath2 erg . the interaction of this ejecta with its surroundings leads to unique phenomena and has important implications to astrophysics .. Please generate the next two sentences of the article

when occurring in binaries , quark - novae ( qne ) have the potential to transform our view of binary evolution and has serious implications to both high - energy astrophysics and cosmology . after a description of the qn and its energetics in section 2 , we briefly review two cases of qne in binaries . the first case is a qn - ia ( section 3 ) which is a qn going off in a short period binary consisting of ( the exploding ) ns and a white dwarf ( wd ) which is the mass reservoir .

Suppose that you have an abstract for a scientific paper: we present low - state iue spectroscopy of the rosat - discovered polar rxj1313.2@xmath03259 . the swp spectrum displays a broad absorption profile , which can be fitted with a two - temperature model of a white dwarf of @xmath1k with a hot spot of @xmath2k which covers @xmath3 of the white dwarf surface . the white dwarf temperature is atypically low for the long orbital period ( 4.18h ) of rxj1313.2@xmath03259 . this low temperature implies either that the system is a young cv in the process of switching on mass transfer or that it is an older cv found in a prolonged state of low accretion rate , much below that predicted by standard evolution theory . in the first case , we can put a lower limit on the life time as pre - cv of @xmath4yrs . in the second case , the good agreement of the white dwarf temperature with that expected from compressional heating suggests that the system has experienced the current low accretion rate for an extended period @xmath5yrs . a possible explanation for the low accretion rate is that rxj1313.2@xmath03259 is a hibernating post nova and observational tests are suggested . . And you have already written the first three sentences of the full article: most fundamental physical stellar parameters of field white dwarfs , such as effective temperature , surface gravity , and magnetic field strength can directly be measured with high precision from spectroscopic observations . assuming a mass - radius relation , both mass and radius may be inferred independently of the distance . determining these properties also for the accreting white dwarfs in cataclysmic variables ( cvs ) is a relatively new research field , essential not only for testing stellar ( binary ) evolution theory , but for understanding the physics of accretion in this whole class of binaries . the last years saw a rapid growth of identified polars , cvs containing a synchronously rotating magnetic white dwarf . despite the large number of know systems ( @xmath6 ) rather little. Please generate the next two sentences of the article

is known about the temperatures of the accreting white dwarfs in these systems . the main reasons for this scarcity are twofold .

Suppose that you have an abstract for a scientific paper: we performed _ spitzer _ infrared spectrograph mapping observations covering nearly the entire extent of the cassiopeia a supernova remnant ( snr ) , producing mid - infrared ( 5.5 - 35 @xmath0 m ) spectra every 5@xmath1 - 10@xmath1 . gas lines of ar , ne , o , si , s and fe , and dust continua were strong for most positions . we identify three distinct ejecta dust populations based on their continuum shapes . the dominant dust continuum shape exhibits a strong peak at 21 @xmath0 m . a line - free map of 21 @xmath0m - peak dust made from the 19 - 23 @xmath0 m range closely resembles the [ ar ii ] , [ o iv ] , and [ ne ii ] ejecta - line maps implying that dust is freshly formed in the ejecta . spectral fitting implies the presence of sio@xmath2 , mg protosilicates , and feo grains in these regions . the second dust type exhibits a rising continuum up to 21 @xmath0 m and then flattens thereafter . this `` weak 21 @xmath0 m '' dust is likely composed of al@xmath2o@xmath3 and c grains . the third dust continuum shape is featureless with a gently rising spectrum and is likely composed of mgsio@xmath3 and either al@xmath2o@xmath3 or fe grains . using the least massive composition for each of the three dust classes yields a total mass of m@xmath4 . using the most - massive composition yields a total mass of m@xmath4 . the primary uncertainty in the total dust mass stems from the selection of the dust composition necessary for fitting the featureless dust as well as 70 @xmath0 m flux . the freshly formed dust mass derived from cas a is sufficient from sne to explain the lower limit on the dust masses in high redshift galaxies . . And you have already written the first three sentences of the full article: the recent discovery of huge quantities of dust ( @xmath5 ) in very high redshifted galaxies and quasars ( isaak et al . 2002 ; bertoldi et al . 2003 ) suggests that dust was produced efficiently in the first generation of supernovae ( sne ) . theoretical studies ( kozasa et al . 1991 ; todini & ferrara 2001 , hereafter tf ; nozawa etal .. Please generate the next two sentences of the article

2003 , n03 ) predicted the formation of a significant quantity of dust ( @xmath6 @xmath7 ) in the ejecta of type ii sne , and the predicted dust mass is believed to be sufficient to account for the quantity of dust observed at high redshifts ( maiolino et al . 2006 ; meikle et al .

Suppose that you have an abstract for a scientific paper: we show that non - locality of quantum mechanics can not lead to superluminal transmission of information , even if most general local operations are allowed , as long as they are linear and trace preserving . in particular , any quantum mechanical approximate cloning transformation does not allow signalling . on the other hand , the no - signalling constraint on its own is not sufficient to prevent a transformation from surpassing the known cloning bounds . we illustrate these concepts on the basis of some examples . . And you have already written the first three sentences of the full article: the impossibility of superluminal communication through the use of quantum entanglement has already been vividly discussed in the past , see for example @xcite . recently this topic has re - entered the stage of present research in the context of quantum cloning : the no - signalling constraint has been used to derive upper bounds for the fidelity of cloning transformations @xcite . as the connection between approximate cloning and no - signalling is still widely debated , we aim at clarifying in this paper the quantum mechanical principles that forbid superluminal communication , and at answering the question whether they are the same principles that set limits to quantum cloning .. Please generate the next two sentences of the article

our scenario throughout the paper for the attempt to transmit information with superluminal speed is the well - known entanglement - based communication scheme@xcite . the idea is the following : two space - like separated parties , say alice and bob , share an entangled state of a pair of two - dimensional quantum systems ( qubits ) , for example the singlet state @xmath0 .

Suppose that you have an abstract for a scientific paper: in this introductory talk we will establish connections between the statistical analysis of galaxy clustering in cosmology and recent work in mainstream spatial statistics . the lecture will review the methods of spatial statistics used by both sets of scholars , having in mind the cross - fertilizing purpose of the meeting series . special topics will be : description of the galaxy samples , selection effects and biases , correlation functions , nearest neighbor distances , void probability functions , fourier analysis , and structure statistics . . And you have already written the first three sentences of the full article: one of the most important motivations of these series of conferences is to promote vigorous interaction between statisticians and astronomers . the organizers merit our admiration for bringing together such a stellar cast of colleagues from both fields . in this third edition , one of the central subjects is cosmology , and in particular , statistical analysis of the large - scale structure in the universe .. Please generate the next two sentences of the article

there is a reason for that the rapid increase of the amount and quality of the available observational data on the galaxy distribution ( also on clusters of galaxies and quasars ) and on the temperature fluctuations of the microwave background radiation . these are the two fossils of the early universe on which cosmology , a science driven by observations , relies . here

Suppose that you have an abstract for a scientific paper: we show that exclusive double - diffractive higgs production , @xmath0 , followed by the @xmath1 decay , could play an important role in identifying a ` light ' higgs boson at the lhc , provided that the forward outgoing protons are tagged . we predict the cross sections for the signal and for all possible @xmath2 backgrounds . ippp/02/41 + dcpt/02/82 + 3 july 2002 * forward proton tagging as a way to identify a light higgs boson at the lhc * a.d . martin , v.a . khoze and m.g . ryskin institute for particle physics phenomenology , + university of durham , dh1 3le , uk . And you have already written the first three sentences of the full article: the identification of the higgs boson(s ) is one of the main goals of the large hadron collider ( lhc ) being built at cern . there are expectations that there exists a ` light ' higgs boson with mass @xmath3 gev . in this mass range , its detection at the lhc will be challenging .. Please generate the next two sentences of the article

there is no obvious perfect detection process , but rather a range of possibilities , none of which is compelling on its own . some of the processes are listed in table 1 , together with the predicted event rates for the integrated luminosity of 30 fb@xmath4 expected over the first two or three year period of lhc running .

Suppose that you have an abstract for a scientific paper: in this work , we propose a new local optimization method to solve a class of nonconvex semidefinite programming ( sdp ) problems . the basic idea is to approximate the feasible set of the nonconvex sdp problem by inner positive semidefinite convex approximations via a parameterization technique . this leads to an iterative procedure to search a local optimum of the nonconvex problem . the convergence of the algorithm is analyzed under mild assumptions . applications in static output feedback control are benchmarked and numerical tests are implemented based on the data from the compl@xmath0ib library . . And you have already written the first three sentences of the full article: we are interested in the following nonconvex semidefinite programming problem : @xmath1 where @xmath2 is convex , @xmath3 is a nonempty , closed convex set in @xmath4 and @xmath5 ( @xmath6 ) are nonconvex matrix - valued mappings and smooth . the notation @xmath7 means that @xmath8 is a symmetric negative semidefinite matrix . optimization problems involving matrix - valued mapping inequality constraints have large number of applications in static output feedback controller design and topology optimization , see , e.g. @xcite . especially , optimization problems with bilinear matrix inequality ( bmi ) constraints have been known to be nonconvex and np - hard @xcite .. Please generate the next two sentences of the article

many attempts have been done to solve these problems by employing convex semidefinite programming ( in particular , optimization with linear matrix inequality ( lmi ) constraints ) techniques @xcite . the methods developed in those papers are based on augmented lagrangian functions , generalized sequential semidefinite programming and alternating directions .

Suppose that you have an abstract for a scientific paper: it is shown using numerical simulations that flow patterns around an obstacle potential moving in a superfluid exhibit hysteresis . in a certain velocity region , there is a bistability between stationary laminar flow and periodic vortex shedding . the bistability exists in two and three dimensional systems . . And you have already written the first three sentences of the full article: the dynamics of fluids can exhibit hysteresis . for example , a flag - like object shows bistability between flapping and nonflapping states @xcite . hysteresis also exists in vortex shedding dynamics behind rigid objects , such as a vibrating cylinder @xcite , a multiple cylinder arrangement @xcite , a long cylinder in a three - dimensional flow @xcite , and a rod in a soap film @xcite . in these experiments ,. Please generate the next two sentences of the article

the transitions between laminar flow and vortex shedding states occur in a hysteretic manner as a function of the reynolds number . it is known that the taylor

Suppose that you have an abstract for a scientific paper: in this article , we study the new q - tensor model previously derived from onsager s molecular theory by han _ et al . _ [ _ arch . rational mech . anal . _ , 215.3 ( 2014 ) , pp . 741 - 809 ] for static liquid crystal modeling . taking density and q - tensor as order parameters , the new q - tensor model not only characterizes important phases while capturing density variation effects , but also remains computationally tractable and efficient . we report the results of two numerical applications of the model , namely the isotropic nematic smectic - a smectic - c phase transitions and the isotropic nematic interface problem , in which density variations are indispensable . meanwhile , we show the connections of the new q - tensor model with classical models including generalized landau - de gennes models , generalized mcmillan models , and the chen - lubensky model . the new q - tensor model is the pivot and an appropriate trade - off between the classical models in three scales . liquid crystals , q - tensor model , density variations , smectic phase , phase transition , isotropic - nematic interface . And you have already written the first three sentences of the full article: a proper choice of order parameters is the most important perspective for building a sound model for liquid crystals . the order parameters should be simple and explanatory in terms of mathematics and physics , while efficient in computations . from the viewpoint of theoretical analysis , it is desirable to adopt order parameters that are as simple as possible in order to capture essential phenomena of liquid crystals , with four phases the most important : isotropic(@xmath0 ) , nematic(@xmath1 ) , smectic - a(@xmath2 ) , and smectic - c(@xmath3 ) phases . as for computational aspects. Please generate the next two sentences of the article

, the order parameters should be discretely representable with reasonable dimensions while keeping the energy functional well - posed , concise , and efficient . the classical models for static liquid crystals can be classified into three scales : molecular models , tensor models , and vector models .

Suppose that you have an abstract for a scientific paper: an extensive search for distant giant radio galaxies on the southern hemisphere is justified . we emphasize the crucial role of optical spectroscopy in determination of their basic physical parameters , i.e. the distance , projected linear size , volume of their lobes or cocoon , luminosity , etc . , and argue that salt will be the best instrument for such a task . # 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: radio galaxies ( rgs ) represent the largest single objects in the universe . powered by an active galactic nucleus ( agn ) jets emerge from the central engine , which very likely is a super - massive black hole accreting matter surrounding it . there is a huge range of linear extent of the rgs : from less than @xmath0 pc gigahertz - peaked spectrum ( gps ) , through @xmath0 . Please generate the next two sentences of the article

@xmath1 pc compact steep spectrum ( css ) , @xmath1 @xmath2 pc normal - size sources , up to greater than 1 mpc

Suppose that you have an abstract for a scientific paper: we obtain the nuclear proximity potential by using semiclassical extended thomas fermi ( etf ) approach in skyrme energy density formalism ( sedf ) , and use it in the extended @xmath0-summed wong formula under frozen density approximation . this method has the advantage of allowing the use of different skyrme forces , giving different barriers . thus , for a given reaction , we could choose a skyrme force with proper barrier characteristics , not - requiring extra barrier lowering " or barrier narrowing " for a best fit to data . for the @xmath1ni+@xmath2mo reaction , the @xmath0-summed wong formula , with effects of deformations and orientations of nuclei included , fits the fusion - evaporation cross section data exactly for the force gski , requiring additional barrier modifications for forces siii and sv . however , the same for other similar reactions , like @xmath3ni+@xmath3ni , fits the data best for siii force . hence , the barrier modification effects in @xmath0-summed wong expression depends on the choice of skyrme force in extended etf method . . And you have already written the first three sentences of the full article: the unexpected behavior of some fusion - evaporation cross sections at energies far below the coulomb barrier , has challenged the theoretical models to explain the , so called , fusion hinderance phenomena in true coupled - channels calculations ( ccc ) for reactions such as @xmath4ni+@xmath4ni , @xmath1ni+@xmath1ni , and @xmath1ni+@xmath2mo @xcite . the ccc could , however , be sensitive to the so far unobserved , hence not - included , high - lying states . misicu and esbensen @xcite were the first who succeeded in describing the above said three reactions in terms of a density - dependent m3y interaction , modified by adding a repulsive core potential @xcite .. Please generate the next two sentences of the article

the repulsive core changes the shape of the inner part of the potential in terms of a thicker barrier ( reduced curvature @xmath5 ) and shallower pocket . here , deformations are included up to hexadecapole ( @xmath6 ) and the orientation degrees of freedom is integrated over all the allowed values in the same plane . the dynamical cluster - decay model ( dcm ) of preformed clusters by gupta and collaborators @xcite is found recently @xcite to have barrier modification effects as the inbuilt property , where barrier lowering " at sub - barrier energies arise in a natural way in its fitting of the only parameter of model , the neck - length parameter .

Suppose that you have an abstract for a scientific paper: we study non - adiabatic charge pumping through single - level quantum dots taking into account coulomb interactions . we show how a truncated set of equations of motion can be propagated in time by means of an auxiliary - mode expansion . this formalism is capable of treating the time - dependent electronic transport for arbitrary driving parameters . we verify that the proposed method describes very precisely the well - known limit of adiabatic pumping through quantum dots without coulomb interactions . as an example we discuss pumping driven by short voltage pulses for various interaction strengths . such finite pulses are particular suited to investigate transient non - adiabatic effects , which may be also important for periodic drivings , where they are much more difficult to reveal . . And you have already written the first three sentences of the full article: in 1983 thouless @xcite proposed a simple pumping mechanism to produce , even in the absence of an external bias , a quantized electron current through a quantum conductor by an appropriate time - dependent variation of the system parameters . experimental realizations of quantum pumps using quantum dots ( qds ) were already reported in the early 90 s @xcite . more recently , due to the technological advances in nano - lithography and control , such experiments have risen to a much higher sophistication level , making it possible to pump electron @xcite and spin @xcite currents through open nanoscale conductors , as well as through single and double qds @xcite .. Please generate the next two sentences of the article

early theoretical investigations where devoted to the adiabatic pumping regime within the single - particle approximation @xcite . this is well justified for experiments with open qds , where interaction effects are believed to be weak @xcite and the typical pumping parameters are slow with respect the characteristic transport time - scales , such as the electron dwell time @xmath0 .

Suppose that you have an abstract for a scientific paper: a case study in bifurcation and stability analysis is presented , in which reduced dynamical system modelling yields substantial new global and predictive information about the behaviour of a complex system . the first smooth pathway , free of pathological and persistent degenerate singularities , is surveyed through the parameter space of a nonlinear dynamical model for a gradient - driven , turbulence shear flow energetics in magnetized fusion plasmas . along the route various obstacles and features are identified and treated appropriately . an organizing centre of low codimension is shown to be robust , several trapped singularities are found and released , and domains of hysteresis , threefold stable equilibria , and limit cycles are mapped . characterization of this rich dynamical landscape achieves unification of previous disparate models for plasma confinement transitions , supplies valuable intelligence on the big issue of shear flow suppression of turbulence , and suggests targeted experimental design , control and optimization strategies . . And you have already written the first three sentences of the full article: the collective dynamics of complex distributed systems often can be usefully described in terms of a superposition of rate processes or frequencies which determine the changes in macroscopically measurable variables as energy flows through the system ; that is , a dynamical model expressed as a system of coupled ordinary differential equations in a few averaged state variables or mode coefficients and several , independently tunable , parameters that represent physical properties or external controls . this type of reduced ( or low - order or low - dimensional ) modelling averages over space , mode spectrum structure , single - particle dynamics and other details , but the payoff lies in its amenity to sophisticated analytic theory and methods that enable us to track important qualitative features in the collective dynamics , such as singularities , bifurcations , and stability changes , broadly over the parameter space . motivated by the need for improved guidance and control of the ( mostly bad ) behaviour of fusion plasmas in magnetic containers , i elaborate in this work a case study in bifurcation and stability analysis in which reduced dynamical system modelling yields new global and predictive information about gradient driven turbulence . Please generate the next two sentences of the article

flow energetics that is complementary to direct numerical simulation and can guide experimental design . reduced dynamical models are powerful tools for describing and analysing complex systems such as turbulent plasmas and fluids , primarily because they are supported by well - developed mathematics that gives qualitative and global insight , such as singularity , bifurcation , stability , and symmetry theory . in principle one can map analytically the bifurcation structure of the entire phase and parameter space of a reduced dynamical system , but this feat is not possible for an infinite - dimensional system , or partial differential equations , and not practicable for systems of high order .

Suppose that you have an abstract for a scientific paper: we present long monte carlo simulations of a simple model of biological macroevolution in which births , deaths , and mutational changes in the genome take place at the level of individual organisms . the model displays punctuated equilibria and flicker noise with a @xmath0-like power spectrum , consistent with some current theories of evolutionary dynamics . . And you have already written the first three sentences of the full article: the long - time dynamics of biological evolution have recently attracted considerable interest among statistical physicists @xcite , who find in this field new and challenging interacting nonequilibrium systems . an example is the bak - sneppen model @xcite , in which interacting species are the basic units , and less fit " species change by mutations " that trigger avalanches that may lead to a self - organized critical state . however , in reality both mutations and natural selection act on _ individual organisms _ , and it is desirable to develop and study models in which this is the case .. Please generate the next two sentences of the article

one such model was recently introduced by hall , christensen , and coworkers @xcite . to enable very long monte carlo ( mc ) simulations of the evolutionary behavior , we have developed a simplified version of this model , for which we here present preliminary results .

Suppose that you have an abstract for a scientific paper: we present the result of a search for a massive color - octet vector particle , ( e.g. a massive gluon ) decaying to a pair of top quarks in proton - antiproton collisions with a center - of - mass energy of 1.96 tev . this search is based on 1.9 fb@xmath0 of data collected using the cdf detector during run ii of the tevatron at fermilab . we study @xmath1 events in the lepton+jets channel with at least one @xmath2-tagged jet . a massive gluon is characterized by its mass , decay width , and the strength of its coupling to quarks . these parameters are determined according to the observed invariant mass distribution of top quark pairs . we set limits on the massive gluon coupling strength for masses between 400 and 800 gev@xmath3 and width - to - mass ratios between 0.05 and 0.50 . the coupling strength of the hypothetical massive gluon to quarks is consistent with zero within the explored parameter space . massive gluon , top quark 13.85.rm , 14.65.ha , 14.80.-j . And you have already written the first three sentences of the full article: the top quark is the heaviest known elementary particle , with a mass very close to the electroweak symmetry - breaking scale . as such , the top could be sensitive to physics beyond the standard model ( sm ) @xcite . new particles decaying to @xmath1 pairs can be scalar or vector , color - singlet or color - octet ; a scalar resonance is predicted in two - higgs - doublets models @xcite ; vector particles appear as massive @xmath4-like bosons in extended gauge theories @xcite , or as kaluza - klein states of the gluon and @xmath4 boson @xcite , or as colorons @xcite .. Please generate the next two sentences of the article

searches for a color - singlet particle decaying to a @xmath1 pair have been performed by cdf and d0 collaborations in run i @xcite and run ii @xcite . in this letter we describe a search for a massive color - octet vector particle @xmath5 , which we call generically a `` massive gluon '' .

Suppose that you have an abstract for a scientific paper: it is well known that the dark matter dominates the dynamics of galaxies and clusters of galaxies . its constituents remain a mystery despite an assiduous search for them over the past three decades . recent results from the satellite - based pamela experiment detect an excess in the positron fraction at energies between @xmath0 gev in the secondary cosmic ray spectrum . other experiments namely atic , hess and fermi show an excess in the total electron ( ps . + @xmath1 ) spectrum for energies greater 100 gev . these excesses in the positron fraction as well as the electron spectrum could arise in local astrophysical processes like pulsars , or can be attributed to the annihilation of the dark matter particles . the second possibility gives clues to the possible candidates for the dark matter in galaxies and other astrophysical systems . in this article , we give a report of these exciting developments . = 22.8 cm .6 true cm . And you have already written the first three sentences of the full article: the evidence for the existence of dark matter in various astrophysical systems has been gathering over the past three decades . it is now well - recognized that the presence of dark matter is required in order to explain the observations of galaxies and other astrophysical systems on larger scales . the clearest support for the existence of dark matter comes from the now well - known observation of nearly flat rotation curves or constant rotation velocity in the outer parts of galaxies @xcite .. Please generate the next two sentences of the article

surprisingly the rotation velocity is observed to remain nearly constant till the last point at which it can be measured . the simple principle of rotational equilibrium then tells one that the amount of dark to visible mass must increase at larger radii .

Suppose that you have an abstract for a scientific paper: it is shown that an exact chiral symmetry can be described for dirac - khler fermions using the two complexes of the geometric discretization . this principle is extended to describe exact flavour projection and it is shown that this necessitates the introduction of a new operator and two new structures of complex . to describe simultaneous chiral and flavour projection , eight complexes are needed in all and it is shown that projection leaves a single flavour of chiral field on each . . And you have already written the first three sentences of the full article: differential geometry has proven to be highly valuable in extracting the geometric meaning of continuum vector theories . of particular interest has been the dirac - khler formulation of fermionic field theory @xcite , which uses the antisymmetry inherent in the product between differential forms to describe the clifford algebra . in order to regularize calculations , we are required to introduce a discrete differential geometry scheme and it would be ideal if this had the same properties as the continuum and the correct continuum limit .. Please generate the next two sentences of the article

however , defining such a scheme has proven to be very challenging . the difficulties are usually exhibited by the hodge star , which maps a form to its complement in the space , and the wedge product between forms . in a discretization , we would like the latter to allow the product rule to be satisfied and we would like both to be local .

Suppose that you have an abstract for a scientific paper: a simple model is presented for the appearance of attraction between two like charged polyions inside a polyelectrolyte solution . the polyions are modeled as rigid cylinders in a continuum dielectric solvent . the strong electrostatic interaction between the polyions and the counterions results in counterion condensation . if the two polyions are sufficiently close to each other their layers of condensed counterions can become correlated resulting in attraction between the macromolecules . to explore the counterion induced attraction we calculate the correlation functions for the condensed counterions . it is found that the correlations are of very short range . for the parameters specific to the double stranded dna , the correlations and the attraction appear only when the surface - to - surface separation is less than @xmath0 . 2 . And you have already written the first three sentences of the full article: in the last few years a new phenomenon has attracted attention of the community of soft condensed matter physicists appearance of attraction between like charged macromolecules in solutions containing multivalent ions . the problem is particularly fascinating because it contradicts our well established intuition that like charged entities should repel @xcite . the fundamental point , however , is that the electrolyte solutions are intrinsically complex systems for which many body interactions play a fundamental role . the attraction between like charged macromolecules is important for many biological systems .. Please generate the next two sentences of the article

one particularly striking example is provided by the condensation of dna by multivalent ions such as @xmath1 , @xmath2 and various polyamines @xcite . this condensation provides an answer to the long standing puzzle of how a highly charged macromolecule , such as the dna , can be confined to a small volume of viral head or nuclear zone in procaryotic cell .

Suppose that you have an abstract for a scientific paper: previous observations of the middle - aged pulsar geminga with _ xmm - newton _ and _ chandra _ have shown an unusual pulsar wind nebula ( pwn ) , with a @xmath0 long central ( axial ) tail directed opposite to the pulsar s proper motion and two @xmath1 long , bent lateral ( outer ) tails . here we report on a deeper _ chandra _ observation ( 78 ks exposure ) and a few additional _ xmm - newton _ observations of the geminga pwn . the new _ chandra _ observation has shown that the axial tail , which includes up to three brighter blobs , extends at least @xmath2 ( i.e. , @xmath3 pc ) from the pulsar ( @xmath4 is the distance scaled to 250 pc ) . it also allowed us to image the patchy outer tails and the emission in the immediate vicinity of the pulsar with high resolution . the pwn luminosity , @xmath5 erg s@xmath6 , is lower than the pulsar s magnetospheric luminosity by a factor of 10 . the spectra of the pwn elements are rather hard ( photon index @xmath7 ) . comparing the two _ chandra _ images , we found evidence of pwn variability , including possible motion of the blobs along the axial tail . the x - ray pwn is the synchrotron radiation from relativistic particles of the pulsar wind ; its morphology is connected with the supersonic motion of geminga . we speculate that the outer tails are either ( 1 ) a sky projection of the limb - brightened boundary of a shell formed in the region of contact discontinuity , where the wind bulk flow is decelerated by shear instability , or ( 2 ) polar outflows from the pulsar bent by the ram pressure from the ism . in the former case , the axial tail may be a jet emanating along the pulsar s spin axis , perhaps aligned with the direction of motion . in the latter case , the axial tail may be the shocked pulsar wind collimated by the ram pressure . . And you have already written the first three sentences of the full article: pulsars lose their spin energy via relativistic pulsar winds ( pws ) of charged particles . the pw shocks in the ambient medium and forms a pulsar wind nebula ( pwn ) whose synchrotron radiation can be observed in a very broad energy range , from the radio to tev @xmath8-rays ( see kaspi et al . 2006 , gaensler & slane 2006 , and kargaltsev & pavlov 2008 [ kp08 hereafter ] for recent reviews ) .. Please generate the next two sentences of the article

the shocked pw is confined between the termination shock ( ts ) and contact discontinuity ( cd ) surface that separates the shocked pw from the shocked ambient medium between the cd and the forward shock ( fs ) . the shapes of the ts , cd , and fs depend on the wind outflow geometry and the ratio of the pulsar s speed to the sound speed in the ambient medium ( the mach number ) , @xmath9 .

Suppose that you have an abstract for a scientific paper: in this paper , a cognitive relay channel is considered , and amplify - and - forward ( af ) relay beamforming designs in the presence of an eavesdropper and a primary user are studied . our objective is to optimize the performance of the cognitive relay beamforming system while limiting the interference in the direction of the primary receiver and keeping the transmitted signal secret from the eavesdropper . we show that under both total and individual power constraints , the problem becomes a quasiconvex optimization problem which can be solved by interior point methods . we also propose two sub - optimal null space beamforming schemes which are obtained in a more computationally efficient way . _ index terms : _ amplify - and - forward relaying , cognitive radio , physical - layer security , relay beamforming . . And you have already written the first three sentences of the full article: the need for the efficient use of the scarce spectrum in wireless applications has led to significant interest in the analysis of cognitive radio systems . one possible scheme for the operation of the cognitive radio network is to allow the secondary users to transmit concurrently on the same frequency band with the primary users as long as the resulting interference power at the primary receivers is kept below the interference temperature limit @xcite . note that interference to the primary users is caused due to the broadcast nature of wireless transmissions , which allows the signals to be received by all users within the communication range .. Please generate the next two sentences of the article

note further that this broadcast nature also makes wireless communications vulnerable to eavesdropping . the problem of secure transmission in the presence of an eavesdropper was first studied from an information - theoretic perspective in @xcite where wyner considered a wiretap channel model . in @xcite ,

Suppose that you have an abstract for a scientific paper: ultrasensitive response motifs , which are capable of converting graded stimulus in binary responses , are very well - conserved in signal transduction networks . although it has been shown that a cascade arrangement of multiple ultrasensitive modules can produce an enhancement of the system s ultrasensitivity , how the combination of layers affects the cascade s ultrasensitivity remains an open - ended question for the general case . here we have developed a methodology that allowed us to quantify the effective contribution of each module to the overall cascade s ultrasensitivity and to determine the impact of sequestration effects in the overall system s ultrasensitivity . the proposed analysis framework provided a natural link between global and local ultrasensitivity descriptors and was particularly well - suited to study the ultrasensitivity in map kinase cascades . we used our methodology to revisit oshaughnessy et al . tunable synthetic mapk cascade , in which they claim to have found a new source of ultrasensitivity : ultrasensitivity generated de novo , which arises due to cascade structure itself . in this respect , we showed that the system s ultrasensitivity in its single - step cascade did not come from a cascading effect but from a ` hidden ' first - order ultrasensitivity process in one of the cascade s layer . our analysis also highlighted the impact of the detailed functional form of a module s response curve on the overall system s ultrasensitivity in cascade architectures . local sensitivity features of the involved transfer functions were found to be of the uttermost importance in this kind of setting and could be at the core of non - trivial phenomenology associated to ultrasensitive motifs . . And you have already written the first three sentences of the full article: sigmoidal input - output response modules are very well - conserved in cell signaling networks that might be used to implement binary responses , a key element in cellular decision processes . additionally , sigmoidal modules might be part of more complex structures , where they can provide the nonlinearities which are needed in a broad spectrum of biological processes [ 1,2 ] , such as multistability [ 3,4 ] , adaptation [ 5 ] , and oscillations [ 6 ] . there are several molecular mechanisms that are able to produce sigmoidal responses such as inhibition by a titration process [ 7,8 ] , zero - order ultrasensitivity in covalent cycles [ 9,10 ] , and multistep activation processes - like multisite phosphorylation [ 11 - 13 ] or ligand binding to multimeric receptors [ 14 ] .. Please generate the next two sentences of the article

sigmoidal curves are characterized by a sharp transition from low to high output following a slight change of the input . the steepness of this transition is called ultrasensitivity [ 15 ] . in general

Suppose that you have an abstract for a scientific paper: linear field perturbations of a black hole are described by the green function of the wave equation that they obey . after fourier decomposing the green function , its two natural contributions are given by poles ( quasinormal modes ) and a largely unexplored branch cut in the complex - frequency plane . we present new analytic methods for calculating the branch cut on a schwarzschild black hole for _ arbitrary _ values of the frequency . the branch cut yields a power - law tail decay for late times in the response of a black hole to an initial perturbation . we determine explicitly the first three orders in the power - law and show that the branch cut also yields a new logarithmic behaviour @xmath0 for late times . before the tail sets in , the quasinormal modes dominate the black hole response . for electromagnetic perturbations , the quasinormal mode frequencies approach the branch cut at large overtone index @xmath1 . we determine these frequencies up to @xmath2 and , formally , to _ arbitrary _ order . highly - damped quasinormal modes are of particular interest in that they have been linked to quantum properties of black holes . the retarded green function for linear field perturbations in black hole spacetimes is of central physical importance in classical and quantum gravity . an understanding of the make - up of the green function is obtained by performing a fourier transform , thus yielding an integration just above the real - frequency ( @xmath3 ) axis . in his seminal paper , leaver @xcite deformed this real-@xmath3 integration in the case of schwarzschild spacetime into a contour on the complex-@xmath3 plane . he thus unraveled three contributions making up the green function : ( 1 ) a high - frequency arc , ( 2 ) a series over poles of the green function ( quasinormal modes qnms ) , and ( 3 ) an integral of modes around a branch cut originating at @xmath4 and extending down the negative imaginary axis ( nia ) , which we refer to as branch cut modes ( bcms ) . the three.... And you have already written the first three sentences of the full article: after carrying out a fourier transform and a multipole decomposition , the radial and time parts of the retarded green function for linear fields on a schwarzschild black hole can be written as @xmath15 where @xmath16 , @xmath17 is the multipole number , @xmath18 , @xmath19 and @xmath20 is the wronskian of the two functions @xmath21 and @xmath22 . these functions are linearly independent solutions of the radial ode @xmath23\right\ } \psi_{\ell}=0 \ ] ] where @xmath24 and @xmath25 . the solutions are uniquely determined when @xmath26 by the boundary conditions : @xmath27 as @xmath28 and @xmath29 as @xmath30 .. Please generate the next two sentences of the article

the behaviour of the radial potential at infinity leads to a branch cut in the radial solution @xmath22 @xcite . the contour of integration in eq.([eq : green ] ) can be deformed in the complex-@xmath3 plane @xcite yielding a contribution from a high - frequency arc , a series over the residues ( the qnms ) and a contribution from the branch cut along the nia : @xmath31 where the bcms are @xmath32 with @xmath33 where @xmath34 $ ] is the discontinuity of @xmath22 across the branch cut .

Suppose that you have an abstract for a scientific paper: stars with radiative envelopes , specifically the upper main sequence chemically peculiar ( ap ) stars , were among the first objects outside our solar system for which surface magnetic fields have been detected . currently magnetic ap stars remains the only class of stars for which high - resolution measurements of both linear and circular polarization in individual spectral lines are feasible . consequently , these stars provide unique opportunities to study the physics of polarized radiative transfer in stellar atmospheres , to analyze in detail stellar magnetic field topologies and their relation to starspots , and to test different methodologies of stellar magnetic field mapping . here i present an overview of different approaches to modeling the surface fields in magnetic a- and b - type stars . in particular , i summarize the ongoing efforts to interpret high - resolution full stokes vector spectra of these stars using magnetic doppler imaging . these studies reveal an unexpected complexity of the magnetic field geometries in some ap stars . . And you have already written the first three sentences of the full article: observational manifestations of magnetic fields in intermediate- and high - mass stars with radiative envelopes differ considerably from the magnetism of solar - type and low - mass stars . as directly observed for the sun and inferred for many late - type stars , vigorous envelope convection and differential rotation give rise to ubiquitous intermittent magnetic fields , which evolve on relatively short time - scales and generally exhibit complex surface topologies . although details of the dynamo operation in late - type stars , in particular the relative importance of the convective and tachocline dynamo mechanisms is a matter of debate @xcite and probably depends on the position in the h - r diagram , it is understood that essentially every cool star is magnetic .. Please generate the next two sentences of the article

chromospheric and x - ray emission and surface temperature inhomogeneities , which are responsible for characteristic photometric variability , provide an indirect evidence of the surface magnetic fields in cool stars . in contrast , stars hotter than about mid - f spectral type and more massive than @xmath01.5@xmath1 are believed to lack a sizable convective zone near the surface and therefore are incapable of generating observable magnetic fields through a dynamo mechanism .

Suppose that you have an abstract for a scientific paper: we studied the radio spectrum of psr b1259 - 63 in an unique binary with be star ls 2883 and showed that the shape of the spectrum depends on the orbital phase . we proposed a qualitative model which explains this evolution . we considered two mechanisms that might influence the observed radio emission : free - free absorption and cyclotron resonance . recently published results have revealed a new aspect in pulsar radio spectra . there were found objects with turnover at high frequencies in spectra , called gigahertz - peaked spectra ( gps ) pulsars . most of them adjoin such interesting environments as hii regions or compact pulsar wind nebulae ( pwn ) . thus , it is suggested that the turnover phenomenon is associated with the environment than being related intrinsically to the radio emission mechanism . having noticed the apparent resemblance between the b1259 - 63 spectrum and the gps , we suggest that the same mechanisms should be responsible for both cases . therefore , the case of b1259 - 63 can be treated as a key factor to explain the gps phenomenon observed for the solitary pulsars with interesting environments and also another types of spectra ( e.g. with break ) . . And you have already written the first three sentences of the full article: generally , the observed radio spectra of most pulsars can be modelled as a power law with negative spectral indices of about -1.8 ( @xcite ) . if a pulsar can be observed at frequencies low enough ( i.e. ) , it may also show a low - frequency turnover in its spectrum ( @xcite ; @xcite ) . on the other hand , lorimer ( 1995 ) mentioned three pulsars which have positive spectral indices in the frequency range 300 - 1600 mhz .. Please generate the next two sentences of the article

later , maron ( 2000 ) re - examined spectra of these pulsars taking into account the data obtained at higher frequencies ( above 1.6 ghz ) and consequently were the first to demonstrate a possible existence of spectra with turnover at high frequencies , about 1 ghz . kijak ( 2011a ) provided a definite evidence for a new type of pulsar radio spectra .

Suppose that you have an abstract for a scientific paper: we study andreev reflection in normal metal - superconductor junctions by using an extended blonder - tinkham - klapwijk model combined with transport calculations based on density functional theory . starting from a parameter - free description of the underlying electronic structure , we perform a detailed investigation of normal metal - superconductor junctions , as the separation between the superconductor and the normal metal is varied . the results are interpreted by means of transverse momentum resolved calculations , which allow us to examine the contributions arising from different regions of the brillouin zone . furthermore we investigate the effect of a voltage bias on the normal metal - superconductor conductance spectra . finally , we consider andreev reflection in carbon nanotubes sandwiched between normal and superconducting electrodes . . And you have already written the first three sentences of the full article: an electron incident on a superconductor from a normal metal , with an energy smaller than the superconducting energy gap , can not propagate into the superconductor and thus should be perfectly reflected . however , andreev discovered a mechanism for transmission , in which an electron may form a cooper pair with another electron and be transmitted across the superconductor . as a consequence of charge conservation a hole must be left behind , which , as a result of momentum conservation , should propagate in a direction opposite to that of the incident electron .. Please generate the next two sentences of the article

this process is termed andreev reflection @xcite . apart from providing a confirmation for the existence of cooper pairs and superconductor energy gaps @xcite , this process may also have applications in spintronics .

Suppose that you have an abstract for a scientific paper: we report a systematic first - principles study on the recent discovered superconducting ba@xmath0k@xmath1fe@xmath2as@xmath2 systems ( @xmath3 = 0.00 , 0.25 , 0.50 , 0.75 , and 1.00 ) . previous theoretical studies strongly overestimated the magnetic moment on fe of the parent compound bafe@xmath2as@xmath2 . using a negative on - site energy @xmath4 , we obtain a magnetic moment 0.83 @xmath5 per fe , which agrees well with the experimental value ( 0.87 @xmath5 ) . k doping tends to increase the density of states at fermi level . the magnetic instability is enhanced with light doping , and is then weaken by increasing the doping level . the energetics for the different k doping sites are also discussed . . And you have already written the first three sentences of the full article: the recent discovery of superconductivity in lafeas[o , f ] has intrigued tremendous interest in layered feas systems.@xcite intensive studies have revealed that , by substituting la with ce , sm , nd , pr , and gd , @xcite the superconducting temperature ( @xmath6 ) can be raised from 26 up to 53.3 k , and even higher ( about 55 k ) under high pressure.@xcite as we know , the parent compound of the these superconductors has a tetrahedral zrcusias - type structure with alternate stacking of tetrahedral feas layers and tetrahedral lao layers , and favors a stripe like antiferromagnetic ( afm ) ground state . the parent compound is not a superconductor but a poor metal with high density of states and low carrier density . @xcite the ground state of the parent compound is supposed to be a spin density wave ( sdw ) ordered state with a stripe like afm configuration .. Please generate the next two sentences of the article

@xcite superconducting occurs when the sdw instability is suppressed by replacing of o with f or importing o vacancies ( electron doping ) , or sr substituting of la ( hole doping).@xcite very recently , the family of feas - based supercondutors has been extended to double layered rfe@xmath2as@xmath2 ( r = sr , ba , ca ) . @xcite the electronic structure of the parent compound has been studied both experimentally @xcite and theoretically .

Suppose that you have an abstract for a scientific paper: in this article , i examine several observational trends regarding protoplanetary disks , debris disks and exoplanets in binary systems in an attempt to constrain the physical mechanisms of planet formation in such a context . binaries wider than about 100au are indistinguishable from single stars in all aspects . binaries in the 5100au range , on the other hand , are associated with shorter - lived but ( at least in some cases ) equally massive disks . furthermore , they form planetesimals and mature planetary systems at a similar rate as wider binaries and single stars , albeit with the peculiarity that they predominantly produce high - mass planets . i posit that the location of a stellar companion influences the relative importance of the core accretion and disk fragmentation planet formation processes , with the latter mechanism being predominant in binaries tighter than 100au . . And you have already written the first three sentences of the full article: the exponentially growing number of known extrasolar planets now enables statistical analyses to probe their formation mechanism . two theoretical frameworks have been proposed to account for the formation of gas giant planets : the slow and gradual core accretion model @xcite , and the fast and abrupt disk fragmentation model @xcite . the debate regarding their relative importance is still ongoing .. Please generate the next two sentences of the article

both mechanisms may contribute to planet formation , depending on the initial conditions in any given protoplanetary disk ( * ? ? ? * and references therein ) . by and large , our understanding of the planet formation process is focused on the case of a single star+disk system . yet ,

Suppose that you have an abstract for a scientific paper: the pivot algorithm for self - avoiding walks has been implemented in a manner which is dramatically faster than previous implementations , enabling extremely long walks to be efficiently simulated . we explicitly describe the data structures and algorithms used , and provide a heuristic argument that the mean time per attempted pivot for @xmath0-step self - avoiding walks is @xmath1 for the square and simple cubic lattices . numerical experiments conducted for self - avoiding walks with up to 268 million steps are consistent with @xmath2 behavior for the square lattice and @xmath3 behavior for the simple cubic lattice . our method can be adapted to other models of polymers with short - range interactions , on the lattice or in the continuum , and hence promises to be widely useful . 0 + + * keywords * self - avoiding walk ; polymer ; monte carlo ; pivot algorithm 0 0 . And you have already written the first three sentences of the full article: the self - avoiding walk ( saw ) model is an important model in statistical physics @xcite . it models the excluded - volume effect observed in real polymers , and exactly captures universal features such as critical exponents and amplitude ratios . it is also an important model in the study of critical phenomena , as it is the @xmath4 limit of the @xmath5-vector model , which includes the ising model ( @xmath6 ) as another instance .. Please generate the next two sentences of the article

indeed , one can straightforwardly simulate saws in the infinite volume limit , which makes this model particularly favorable for the calculation of critical parameters . exact results are known for self - avoiding walks in two dimensions @xcite and for @xmath7 ( mean - field behavior has been proved for @xmath8 @xcite ) , but not for the most physically interesting case of @xmath9 .

Suppose that you have an abstract for a scientific paper: we study distribution of orbits of a lattice @xmath0 in the the space @xmath1 of @xmath2-frames in @xmath3 ( @xmath4 ) . examples of dense @xmath5-orbits are known from the work of dani , raghavan , and veech . we show that dense orbits of @xmath5 are uniformly distributed in @xmath1 with respect to an explicitly described measure . we also establish analogous result for lattices in @xmath6 that act on the space of isotropic @xmath7-frames . . And you have already written the first three sentences of the full article: let @xmath8 and @xmath1 be the space of @xmath2-frames in @xmath3 ( i.e. the space of @xmath2-tuples of linearly independent vectors in @xmath3 ) , @xmath9 . the group @xmath10 acts on this space as follows : @xmath11 the action is transitive for @xmath12 . let @xmath5 be a lattice in @xmath10 ; that is , a discrete subgroup in @xmath10 such that the factor space @xmath13 has finite volume ( e.g. @xmath14 ) . the main result of this paper concerns distribution of @xmath5-orbits in @xmath1 . when @xmath15 , every orbit of @xmath5 is discrete the situation becomes much more interesting for @xmath12 .. Please generate the next two sentences of the article

let us recall known results : * ( dani , raghavan @xcite ) * [ th_dr ] let @xmath14 , and @xmath16 be an @xmath2-frame in @xmath3 , @xmath4 . then the orbit @xmath17 is dense in @xmath1 iff the space spanned by @xmath18 contains no nonzero rational vectors . * ( veech @xcite ) * [ th_ve ] if @xmath5 is a cocompact lattice in @xmath10 , then every orbit of @xmath5 in @xmath1 , @xmath4 , is dense .

Suppose that you have an abstract for a scientific paper: we calculate the lateral casimir force between corrugated parallel plates , described by @xmath0-function potentials , interacting through a scalar field , using the multiple scattering formalism . the contributions to the casimir energy due to uncorrugated parallel plates is treated as a background from the outset . we derive the leading- and next - to - leading - order contribution to the lateral casimir force for the case when the corrugation amplitudes are small in comparison to corrugation wavelengths . we present explicit results in terms of finite integrals for the case of the dirichlet limit , and exact results for the weak - coupling limit , for the leading- and next - to - leading - orders . the correction due to the next - to - leading contribution is significant . in the weak coupling limit we calculate the lateral casimir force exactly in terms of a single integral which we evaluate numerically . exact results for the case of the weak limit allows us to estimate the error in the perturbative results . we show that the error in the lateral casimir force , in the weak coupling limit , when the next - to - leading order contribution is included is remarkably low when the corrugation amplitudes are small in comparison to corrugation wavelengths . we expect similar conclusions to hold for the dirichlet case . the analogous calculation for the electromagnetic case should reduce the theoretical error sufficiently for comparison with the experiments . . And you have already written the first three sentences of the full article: the casimir force , as exhibited between neutral metallic parallel plates , was discovered theoretically in 1948 @xcite . the casimir torque between asymmetric materials was first studied in 1973 @xcite . recently , theoretical study of the lateral casimir force between corrugated parallel plates was pioneered and developed by the mit group in @xcite . in particular , in @xcite , the authors evaluated analytic expressions for the lateral casimir force , to the leading order , between two corrugated parallel plates perturbatively .. Please generate the next two sentences of the article

experimentally , the casimir interaction between corrugated surfaces was explored during the same period of time by roy and mohideen in @xcite . this experiment measured the lateral casimir force between a plate , with small sinusoidal corrugations , and a large sphere with identical corrugations .

Suppose that you have an abstract for a scientific paper: we present an @xmath0-covariant quantization of the free electromagnetic field in conformally flat spaces ( cfs ) . a cfs is realized in a six - dimensional space as an intersection of the null cone with a given surface . the smooth move of the latter is equivalent to perform a weyl rescaling . this allows to transport the @xmath0-invariant quantum structure of the maxwell field from minkowski space to any cfs . calculations are simplified and the cfs wightman two - point functions are given in terms of their minkowskian counterparts . the difficulty due to gauge freedom is surpassed by introducing two auxiliary fields and using the gupta - bleuler quantization scheme . the quantum structure is given by a vacuum state and creators / annihilators acting on some hilbert space . in practice , only the hilbert space changes under weyl rescalings . also the quantum @xmath0-invariant free maxwell field does not distinguish between two cfss . . And you have already written the first three sentences of the full article: the @xmath0-invariance of the maxwell equation was discovered by cunningham and bateman a century ago . however in order to quantize the maxwell field and due to gauge freedom , a gauge fixing condition is necessary . the lorenz gauge is usually used , which breaks the @xmath0 invariance .. Please generate the next two sentences of the article

nonetheless since such a symmetry mights apear to lack physical meaning , its breaking does not bother many people @xcite . the purpose of the present paper is to demonstrate the benefits of keeping this fundamental symmetry when quantizing the maxwell field in conformally flat spaces ( cfs ) .

Suppose that you have an abstract for a scientific paper: expressions for sudakov form factors for heavy quarks are presented . they are used to construct resummed jet rates in @xmath0 annihilation . predictions are given for production of bottom quarks at lep and top quarks at the linear collider . . And you have already written the first three sentences of the full article: the formation of jets is the most prominent feature of perturbative qcd in @xmath0 annihilation into hadrons . jets can be visualized as large portions of hadronic energy or , equivalently , as a set of hadrons confined to an angular region in the detector . in the past , this qualitative definition was replaced by quantitatively precise schemes to define and measure jets , such as the cone algorithms of the weinberg sterman @xcite type or clustering algorithms , e.g. the jade @xcite or the durham scheme ( @xmath1 scheme ) @xcite .. Please generate the next two sentences of the article

a refinement of the latter one is provided by the cambridge algorithm @xcite . equipped with a precise jet definition the determination of jet production cross sections and their intrinsic properties is one of the traditional tools to investigate the structure of the strong interaction and to deduce its fundamental parameters . in the past decade , precision measurements , especially in @xmath0 annihilation , have established both the gauge group structure underlying qcd and the running of its coupling constant @xmath2 over a wide range of scales . in a similar way ,

Suppose that you have an abstract for a scientific paper: we present a new model for the observed ly@xmath0 blobs ( labs ) within the context of the standard cold dark matter model . in this model , labs are the most massive halos with the strongest clustering ( proto - clusters ) undergoing extreme starbursts in the high - z universe . aided by calculations of detailed radiative transfer of @xmath1 photons through ultra - high resolution ( @xmath2pc ) large - scale ( @xmath3mpc ) adaptive mesh - refinement cosmological hydrodynamic simulations with galaxy formation , this model is shown to be able to , for the first time , reproduce simultaneously the global @xmath1 luminosity function and luminosity - size relation of the observed labs . physically , a combination of dust attenuation of @xmath1 photons within galaxies , clustering of galaxies , and complex propagation of @xmath1 photons through circumgalactic and intergalactic medium gives rise to the large sizes and frequently irregular isophotal shapes of labs that are observed . a generic and unique prediction of this model is that there should be strong far - infrared ( fir ) sources within each lab , with the most luminous fir source likely representing the gravitational center of the proto - cluster , not necessarily the apparent center of the @xmath1 emission of the lab or the most luminous optical source . upcoming alma observations should unambiguously test this prediction . if verified , labs will provide very valuable laboratories for studying formation of galaxies in the most overdense regions of the universe at a time when global star formation is most vigorous . = 1 . And you have already written the first three sentences of the full article: the physical origin of spatially extended ( tens to hundreds of kiloparsecs ) luminous ( @xmath4erg / s ) ly@xmath0 sources , also known as ly@xmath0 blobs ( labs ) first discovered more than a decade ago ( e.g. , * ? ? ? * ; * ? ? ? * ; * ? ? ?. Please generate the next two sentences of the article

* ; * ? ? ? * ) , remains a mystery . by now

Suppose that you have an abstract for a scientific paper: the problem of sheath formation in front of a conductive planar plate inserted into the plasma is formulated . initially , the plate is assumed to be neutral . it is shown that the charging - up process of the plate is accompanied by the excitation of electron plasma waves . _ @xmath0 plasma physics department , faculty of physics , al . i. cuza university , ro-700506 iasi , romania , + @xmath1j . stefan institute , university of ljubljana , jamova 39 , slo-1000 ljubljana , slovenia , + @xmath2 association euratom - oaw , department of theoretical physics , university of innsbruck , a-6020 innsbruck , austria , + @xmath3 permanent address : institute of physics , georgian academy of sciences , 380077 tbilisi , georgia , + @xmath4association euratom - oaw , department of ion physics , university of innsbruck , a-6020 innsbruck , austria _ . And you have already written the first three sentences of the full article: investigations of sheath formation in front of a floating plate have hitherto been restricted to fluid studies on the ion time scale [ 1 ] . by contrast , the response of the plasma in the very early stages of sheath formation is not well known . in this paper , we present pic simulations of the plasma dynamics over just a few electron plasma periods after the beginning of the process . these simulations have been performed by means of the bit1 code [ 2 ] , developed on the basis of the xpdp1 code from u. c. berkeley [ 3 ] . a floating plate is placed in contact with a uniform , quasi - neutral plasma , which is assumed to be infinitely extended on one side . due to the higher thermal velocity of the electrons ,. Please generate the next two sentences of the article

the plate starts charging up negatively , so that electrons are gradually repelled , ions are attracted , and a positive - space - charge sheath begins to form . an electron plasma wave is observed the properties of which strongly depend on the plasma characteristics ( electron and ion temperatures , plasma density , etc . ) .

Suppose that you have an abstract for a scientific paper: the shell - model monte carlo ( smmc ) technique transforms the traditional nuclear shell - model problem into a path - integral over auxiliary fields . we describe below the method and its applications to four physics issues : calculations of @xmath0-@xmath1- shell nuclei , a discussion of electron - capture rates in @xmath1-shell nuclei , exploration of pairing correlations in unstable nuclei , and level densities in rare earth systems . . And you have already written the first three sentences of the full article: studies of nuclei far from stability have long been a goal of nuclear science . nuclei on either side of the stability region , either neutron - rich or deficient , are being produced at new radioactive beam facilities across the world . at these facilities , and with the help of advances in nuclear many - body theory , the community will address many of the key physics issues including : mapping of the neutron and proton drip lines , thus exploring the limits of stability ; understanding effects of the continuum on weakly bound nuclear systems ; understanding the nature of shell gap modifications in very neutron - rich systems ; determining nuclear properties needed for astrophysics ; investigating deformation , spin , and pairing properties of systems far from stability ; and analyzing microscopically unusual shapes in unstable nuclei .. Please generate the next two sentences of the article

the range and diversity of nuclear behavior , as indicated in the above list of ongoing and planned experimental investigations , have naturally engendered a host of theoretical models . short of a complete solution to the many - nucleon problem , the interacting shell model is widely regarded as the most broadly capable description of low - energy nuclear structure , and the one most directly traceable to the fundamental many - body problem .

Suppose that you have an abstract for a scientific paper: a systematic analysis is performed for quantum phase transitions in a bond - alternative one - dimensional ising model with a dzyaloshinskii - moriya ( dm ) interaction by using the fidelity of ground state wave functions based on the infinite matrix product states algorithm . for an antiferromagnetic phase , the fidelity per lattice site exhibits a bifurcation , which shows spontaneous symmetry breaking in the system . a critical dm interaction is inversely proportional to an alternating exchange coupling strength for a quantum phase transition . further , a finite - entanglement scaling of von neumann entropy with respect to truncation dimensions gives a central charge @xmath0 at the critical point . . And you have already written the first three sentences of the full article: recent advanced material technologies have made it possible to access low - dimensional quantum systems . furthermore , material synthesis has offered a great opportunity to explore more intriguing lower - dimensional spin systems rather than well - understood conventional spin systems @xcite . in such a low - dimensional system , for instance , alternating bond interactions and/or less symmetry interactions in spin lattices can be realizable in synthesizing two different magnetic atoms . of particular importance , therefore , is understanding quantum phase transitions in which one - dimensional spin systems are unlikely found naturally . normally , quantum fluctuations in a low - dimensional spin system are stronger than higher dimensional spin systems @xcite .. Please generate the next two sentences of the article

quantum phase transitions driven by stronger quantum fluctuations then exhibit more interesting and novel quantum phenomena in low - dimensional spin systems . the effects of alternating bond interactions , especially , have been intensively studied theoretically in spin systems such as antiferromagnetic heisenberg chains @xcite , heisenberg chains with next - nearest - neighbor bond alternations @xcite , a tetrameric heisenberg antiferromagnetic chain @xcite , and two - leg spin ladders @xcite .

Suppose that you have an abstract for a scientific paper: the double dissociation photoproduction cross section for the process @xmath0 , in which the systems @xmath1 and @xmath2 are separated by a large rapidity gap , is measured at large 4-momentum transfer squared @xmath3 by the h1 collaboration at hera . this measurement provides for the first time a direct measurement of the energy dependence of the gap production process at high @xmath4 . . And you have already written the first three sentences of the full article: it is now an established experimental fact that there are events with large rapidity gaps in the hadronic final state in which there is a large momentum transfer across the gap . such events have been observed at both the tevatron @xcite and hera @xcite in the rapidity gaps between jets process suggested for study by bjorken @xcite . the issue now for experimentalists and theorists alike is to address the question of what underlying dynamical process is responsible for such striking events .. Please generate the next two sentences of the article

it is clear that conventional regge phenomenology can not provide an answer , since the soft pomeron contribution has died away at much lower @xmath4 values due to shrinkage . the two best developed models currently available are the bfkl pomeron @xcite , calculated within the leading logarithmic approximation ( lla ) by mueller and tang @xcite and implemented into the herwig monte carlo @xcite , and the soft colour rearrangement model @xcite .

Suppose that you have an abstract for a scientific paper: we construct explicit bps and non - bps solutions of the yang - mills equations on the noncommutative space @xmath0 which have manifest spherical symmetry . using @xmath1-equivariant dimensional reduction techniques , we show that the solutions imply an equivalence between instantons on @xmath0 and nonabelian vortices on @xmath2 , which can be interpreted as a blowing - up of a chain of d0-branes on @xmath2 into a chain of spherical d2-branes on @xmath0 . the low - energy dynamics of these configurations is described by a quiver gauge theory which can be formulated in terms of new geometrical objects generalizing superconnections . this formalism enables the explicit assignment of d0-brane charges in equivariant k - theory to the instanton solutions . hep - th/0504025 + itp uh05/05 + hwm0503 + empg0504 + 1.5 cm * quiver gauge theory of nonabelian vortices + and noncommutative instantons in higher dimensions * alexander d. popov + _ institut fr theoretische physik , universitt hannover + appelstrae 2 , 30167 hannover , germany _ + and + _ bogoliubov laboratory of theoretical physics , jinr + 141980 dubna , moscow region , russia _ + email : popov@itp.uni-hannover.de + richard j. szabo + _ department of mathematics , heriot - watt university + colin maclaurin building , riccarton , edinburgh eh14 4as , u.k . _ + email : r.j.szabo@ma.hw.ac.uk . And you have already written the first three sentences of the full article: one of the most basic questions that arises in trying to understand the nonperturbative structure of string theory concerns the classification of vector bundles over real and complex manifolds . in the presence of d - branes one encounters gauge theories in spacetime dimensionalities up to ten . already more than 20 years ago , bps - type equations in higher dimensions were proposed @xcite as a generalization of the self - duality equations in four dimensions . for nonabelian gauge theory on a khler manifold the most natural bps condition lies in the donaldson - uhlenbeck - yau equations @xcite , which arise , for instance , in compactifications down to four - dimensional minkowski spacetime as the condition for at least one unbroken supersymmetry . while the criteria for solvability of these bps equations are by now very well understood , in practice it is usually quite difficult to write down explicit solutions of them .. Please generate the next two sentences of the article

one recent line of attack has been to consider noncommutative deformations of these field theories @xcite@xcite . in certain instances , d - branes can be realized as noncommutative solitons @xcite , which is a consequence @xcite of the relationship between d - branes and k - theory @xcite@xcite .

Suppose that you have an abstract for a scientific paper: young star clusters with masses similar to those of classical old globular clusters are observed not only in starbursts , mergers or otherwise disturbed galaxies , but also in normal spiral galaxies . some young clusters with masses as high as @xmath0 have been found in the disks of isolated spirals . dynamical mass estimates are available for a few of these clusters and are consistent with kroupa - type imfs . the luminosity ( and possibly mass- ) functions of young clusters are usually well approximated by power - laws . thus , massive clusters at the tail of the distribution are naturally rare , but appear to be present whenever clusters form in large numbers . while bound star clusters may generally form with a higher efficiency in environments of high star formation rate , many of the apparent differences between clusters in starbursts and `` normal '' galaxies might be simply due to sampling effects . it is a human habit to characterise those things with which we are most familiar as normal . although large spiral galaxies are not the most common type of galaxy in the universe , we happen to live within one and many astronomers would probably tend to characterise the milky way as a fairly normal galaxy . thus , at least for the purpose of this paper , `` normal '' galaxies mostly refer to non - interacting star forming disk galaxies . our location within the milky way gives us a unique perspective from which we can study many of its properties in great detail , and it naturally provides a benchmark for comparison with other galaxies . nevertheless , we should question whether it is justified to apply results obtained from studies of our own galaxy to other galaxies which may appear superficially similar to it . in the context of this workshop , it is of particular relevance to ask how similar the cluster system in the milky way is to those in other galaxies . an increasing amount of observational evidence is pointing to the conclusion that many spirals host `` young massive.... And you have already written the first three sentences of the full article: it may be worth recalling some of the main properties of the milky way open cluster system . the census of open clusters is still highly incomplete beyond distances of a few kpc from the sun , although the situation is improving with new surveys such as 2mass ( see e.g. the contributions by carpenter and hanson in this volume ) . the luminosity function of milky way open clusters was analysed by @xcite , who found it to be well modelled by a power - law @xmath1 over the range @xmath2 .. Please generate the next two sentences of the article

however , they also noted that extrapolation of this luminosity function would predict about 100 clusters as bright as @xmath3 in the galaxy , clearly at odds with observations , and thus suggested some flattening of the lf slope at higher luminosities . the brightest known young clusters ( e.g. ngc 3603 , @xmath4 and @xmath5 per ) have absolute @xmath6 magnitudes of @xmath7 , corresponding to total masses of several thousand . recently , there have been claims that the cyg ob2 association might be an even more massive cluster @xcite , but this object is probably too diffuse to be a bound star cluster ( though it does have a compact core ) .

Suppose that you have an abstract for a scientific paper: we analyse what happens with two merging constituent monopoles for the @xmath0 caloron . identified through degenerate eigenvalues ( the singularities or defects of the abelian projection ) of the polyakov loop , it follows that there are defects that are not directly related to the actual constituent monopoles . -1 cm . And you have already written the first three sentences of the full article: finite temperature instantons ( calorons ) have a rich structure if one allows the polyakov loop , @xmath1 in the periodic gauge @xmath2 , to be non - trivial at spatial infinity ( specifying the holonomy ) . it implies the spontaneous breakdown of gauge symmetry . for a charge one @xmath3 caloron , the location of the @xmath4 constituent monopoles can be identified through : i. points where two eigenvalues of the polyakov loop coincide , which is where the @xmath5 symmetry is partially restored to @xmath6 .. Please generate the next two sentences of the article

ii . the centers of mass of the ( spherical ) lumps . iii . the dirac monopoles ( or rather dyons , due to self - duality ) as the sources of the abelian field lines , extrapolated back to the cores .

Suppose that you have an abstract for a scientific paper: we present high signal to noise ratio _ spitzer _ infrared spectrograph observations of 17 virgo early - type galaxies . the galaxies were selected from those that define the colour - magnitude relation of the cluster , with the aim of detecting the silicate emission of their dusty , mass - losing evolved stars . to flux calibrate these extended sources we have devised a new procedure that allows us to obtain the intrinsic spectral energy distribution and to disentangle resolved and unresolved emission within the same object . we have found that thirteen objects of the sample ( 76% ) are passively evolving galaxies with a pronounced broad silicate feature which is spatially extended and likely of stellar origin , in agreement with model predictions . the other 4 objects ( 24% ) are characterized by different levels of activity . in ngc 4486 ( m 87 ) the line emission and the broad silicate emission are evidently unresolved and , given also the typical shape of the continuum , they likely originate in the nuclear torus . ngc 4636 shows emission lines superimposed on extended ( i.e. stellar ) silicate emission , thus pushing the percentage of galaxies with silicate emission to 82% . finally , ngc 4550 and ngc 4435 are characterized by polycyclic aromatic hydrocarbon ( pah ) and line emission , arising from a central unresolved region . a more detailed analysis of our sample , with updated models , will be presented in a forthcoming paper . # 1 # 2 _ mem . soc . astron . it . _ * # 1 * , # 2 # 1 # 2 _ the messenger _ # 1 , # 2 # 1 # 2 astron . nach . # 1 , # 2 # 1 # 2 a&a # 1 , # 2 # 1 # 2 a&a # 1 , l#2 # 1 # 2 a&ar # 1 , # 2 # 1 # 2 a&as # 1 , # 2 # 1 # 2 aj # 1 , # 2 # 1 # 2 ara&a # 1,#2 # 1 # 2 apj # 1 , # 2 # 1 # 2 apj # 1 , l#2 # 1 # 2 apjs # 1 , # 2 # 1 # 2 ap&ss # 1 , # 2 # 1 # 2 adv . space res . # 1 , # 2 # 1 # 2 bull . astron . inst . czechosl . # 1 , # 2 # 1 # 2 j. quant . spectrosc . radiat . transfer # 1 , # 2 # 1 # 2 mnras # 1 , # 2 # 1 # 2 mem.... And you have already written the first three sentences of the full article: bressan , granato & silva @xcite have suggested that the presence of dusty circumstellar envelopes around asymptotic giant branch(agb ) stars should leave a signature , a clear excess at 10 @xmath0 m , in the mid infrared ( mir ) spectral region of passively evolving stellar systems . early detections of such an excess were suspected in m32 ( impey et al . 1986 ) from ground based observations , and in a few ellipticals observed with isocam ( bregman et al . the first unambiguous confirmation of the existence of this feature , though barely resolved , was found in the iso cvf spectrum of ngc 1399 ( bressan et al . 2001 ) . since agb stars. Please generate the next two sentences of the article

are luminous tracers of intermediate age and old stellar populations , an accurate analysis of this feature has been suggested as a complementary way to disentangle age and metallicity effects among early type galaxies ( bressan et al . 1998 ; 2001 ) . more specifically ,

Suppose that you have an abstract for a scientific paper: directional dark matter detectors will be able to record the recoil momentum spectrum of nuclei hit by dark matter wimps . we show that the recoil momentum spectrum is the radon transform of the wimp velocity distribution . this allows us to obtain analytic expressions for the recoil spectra of a variety of velocity distributions . we comment on the possibility of inverting the recoil momentum spectrum and obtaining the three - dimensional wimp velocity distribution from data . . And you have already written the first three sentences of the full article: the identification of dark matter is one of the major open questions in physics , astrophysics , and cosmology . recent cosmological observations together with constraints from primordial nucleosynthesis point to the presence of non - baryonic dark matter in the universe . the nature of this non - baryonic dark matter is still unknown .. Please generate the next two sentences of the article

one of the preferred candidates for non - baryonic dark matter is a weakly interacting massive particle ( wimp ) . substantial efforts have been dedicated to wimp searches in the last decades @xcite .

Suppose that you have an abstract for a scientific paper: we investigate the ( electro-)geodesic structure of the majumdar - papapetrou solution representing static charged black holes in equilibrium . we assume only two point sources , imparting thus the spacetime axial symmetry . we study electrogeodesics both in and off the equatorial plane and explore the stability of circular trajectories via geodesic deviation equation . in contrast to the classical newtonian situation , we find regions of spacetime admitting two different angular frequencies for a given radius of the circular electrogeodesic . we look both at the weak- and near - field limits of the solution . we use analytic as well as numerical methods in our approach . _ keywords _ : electrogeodesic , majumdar - papapetrou , black hole , extreme reissner - nordstrm . And you have already written the first three sentences of the full article: study of geodesics has been one of the main tools in the investigation of the physical properties of spacetimes since the very establishment of general relativity for a general review of both geodesics and electrogeodesics for the reissner - nordstrm as well as other spacetimes , see , for example , the classical book by chandrasekhar @xcite . besides revealing the causal structure of the spacetime , geodesics help us build our intuition about the solution and connect it to the classical newtonian case , if possible . it may also be possible to interpret parameters appearing in the solution and restrict their ranges based on physically reasonable requirements on the behavior of geodesics . until this day , new papers are still appearing on geodesics in kerr @xcite , which is certainly very important for astrophysical applications , or even in schwarzschild @xcite . with the advent of the ads. Please generate the next two sentences of the article

/ cft conjecture there has been renewed interest in the geodetical structure of spacetimes involving the cosmological constant @xcite . in these cases , there is usually some test - particle motion which is not allowed in the schwarzschild spacetime or the interval of admissible radii extends farther , which is also the case here as we can reach the axis . the different allowed ranges could perhaps enable us to distinguish between the various solutions through direct observation .

Suppose that you have an abstract for a scientific paper: the parallel chip - firing game is a periodic automaton on graphs in which vertices `` fire '' chips to their neighbors . in 1989 , bitar conjectured that the period of a parallel chip - firing game with @xmath0 vertices is at most @xmath0 . though this conjecture was disproven in 1994 by kiwi et . al . , it has been proven for particular classes of graphs , specifically trees ( bitar and goles , 1992 ) and the complete graph @xmath1 ( levine , 2008 ) . we prove bitar s conjecture for complete bipartite graphs and characterize completely all possible periods for positions of the parallel chip - firing game on such graphs . furthermore , we extend our construction of all possible periods for games on the bipartite graph to games on complete @xmath2-partite graphs , @xmath3 , and prove some pertinent lemmas about games on general simple connected graphs . tian - yi jiang . And you have already written the first three sentences of the full article: the parallel chip - firing game or candy - passing game is a periodic automaton on graphs in which vertices , each of which contains some nonnegative number of chips , `` fire '' exactly one chip to each of their neighbors if possible . formally , let @xmath4 be an undirected graph with vertex set @xmath5 and edge set @xmath6 . define the _ parallel chip - firing game _ on @xmath4 to be an automaton governed by the following rules : * at the beginning of the game , @xmath7 chips are placed on each vertex @xmath8 in @xmath4 , where @xmath7 is a nonnegative integer . position _ of the parallel chip - firing game , denoted by @xmath9 , be the ordered pair @xmath10 containing the graph and the number of chips on each vertex of the graph . * at each _ move _ or _ step _ of the game , if a vertex @xmath8 has at least as many chips as it has neighbors , it will give ( _ fire _ ) exactly one chip to each neighbor .. Please generate the next two sentences of the article

such a vertex is referred to as _ firing _ ; otherwise , it is _ non - firing_. all vertices fire simultaneously ( in parallel ) . we employ the notation of levine @xcite .

Suppose that you have an abstract for a scientific paper: we propose a real - time machine translation system that allows users to select a news category and to translate the related live news articles from arabic , czech , danish , farsi , french , german , italian , polish , portuguese , spanish and turkish into english . the moses - based system was optimised for the news domain and differs from other available systems in four ways : ( 1 ) news items are automatically categorised on the source side , before translation ; ( 2 ) named entity translation is optimised by recognising and extracting them on the source side and by re - inserting their translation in the target language , making use of a separate entity repository ; ( 3 ) news titles are translated with a separate translation system which is optimised for the specific style of news titles ; ( 4 ) the system was optimised for speed in order to cope with the large volume of daily news articles . . And you have already written the first three sentences of the full article: being able to read news from other countries and written in other languages allows readers to be better informed . it allows them to detect national news bias and thus improves transparency and democracy . existing online translation systems such as _ google translate _ and _ _ bing translator _ _ are thus a great service , but the number of documents that can be submitted is restricted ( google will even entirely stop their service in 2012 ) and submitting documents means disclosing the users interests and their ( possibly sensitive ) data to the service - providing company . for these reasons , we have developed our in - house machine translation system onts .. Please generate the next two sentences of the article

its translation results will be publicly accessible as part of the europe media monitor family of applications , @xcite , which gather and process about 100,000 news articles per day in about fifty languages . onts is based on the open source phrase - based statistical machine translation toolkit moses @xcite , trained mostly on freely available parallel corpora and optimised for the news domain , as stated above .

Suppose that you have an abstract for a scientific paper: on 17 january 2005 two fast coronal mass ejections were recorded in close succession during two distinct episodes of a 3b / x3.8 flare . both were accompanied by metre - to - kilometre type - iii groups tracing energetic electrons that escape into the interplanetary space and by decametre - to - hectometre type - ii bursts attributed to cme - driven shock waves . a peculiar type - iii burst group was observed below 600 khz 1.5 hours after the second type iii group . it occurred without any simultaneous activity at higher frequencies , around the time when the two cmes were expected to interact . we associate this emission with the interaction of the cmes at heliocentric distances of about 25 r@xmath0 . near - relativistic electrons observed by the epam experiment onboard ace near 1 au revealed successive particle releases that can be associated with the two flare / cme events and the low - frequency type - iii burst at the time of cme interaction . we compare the pros and cons of shock acceleration and acceleration in the course of magnetic reconnection for the escaping electron beams revealed by the type iii bursts and for the electrons measured _ in situ_. . And you have already written the first three sentences of the full article: the acceleration of charged particles to high energies in the solar corona is related to flares , which reveal the dissipation of magnetically stored energy in complex magnetic field structures of the low corona , and to coronal mass ejections ( cmes ) , which are large - scale , complex magnetic - field - plasma structures ejected from the sun . cmes can drive bow shocks , and their perturbation of the coronal magnetic field can also give rise to magnetic reconnection , where energy can be released in a similar way as during flares . when several cmes are launched along the same path , a faster cme may overtake a slower preceding one , and the two cmes can merge into a single structure .. Please generate the next two sentences of the article

for this phenomenon @xcite introduced the term _ cme cannibalism_. the cme - cme interaction was found associated with a characteristic low - frequency continuum radio emission . @xcite interpreted this type of activity as the radio signature of non - thermal electrons originating either during reconnection between the two cmes or as the shock of the second , faster cme travels through the body of the first ( see * ? ? ?

Suppose that you have an abstract for a scientific paper: one of the main challenges faced by biometric - based authentication systems is the need to offer secure authentication while maintaining the privacy of the biometric data . previous solutions , such as secure sketch and fuzzy extractors , rely on assumptions that can not be guaranteed in practice , and often affect the authentication accuracy . in this paper , we introduce honeyfaces : the concept of adding a large set of synthetic faces ( indistinguishable from real ) into the biometric `` password file '' . this password inflation protects the privacy of users and increases the security of the system without affecting the accuracy of the authentication . in particular , privacy for the real users is provided by `` hiding '' them among a large number of fake users ( as the distributions of synthetic and real faces are equal ) . in addition to maintaining the authentication accuracy , and thus not affecting the security of the authentication process , honeyfaces offer several security improvements : increased exfiltration hardness , improved leakage detection , and the ability to use a two - server setting like in honeywords . finally , honeyfaces can be combined with other security and privacy mechanisms for biometric data . we implemented the honeyfaces system and tested it with a password file composed of 270 real users . the `` password file '' was then inflated to accommodate up to @xmath0 users ( resulting in a 56.6 tb `` password file '' ) . at the same time , the inclusion of additional faces does not affect the true acceptance rate or false acceptance rate which were 93.33% and 0.01% , respectively . biometrics ( access control ) , face recognition , privacy . And you have already written the first three sentences of the full article: biometric authentication systems are becoming prevalent in access control and in consumer technology . in such systems , the user submits their user name and his / her biometric sample , which is compared to the stored biometric template associated with this user name ( one - to - one matching ) . the popularity of biometric - based systems stems from a popular belief that such authentication systems are more secure and user friendly than systems based on passwords . at the same time. Please generate the next two sentences of the article

, the use of such systems raises concerns about the security and privacy of the stored biometric data . unlike passwords , replacing a compromised biometric trait is impossible , since biometric traits ( e.g. , face , fingerprint , and iris ) are considered to be unique . therefore , the security of biometric templates is an important issue when considering biometric based systems .

Suppose that you have an abstract for a scientific paper: in a new classification of merging binary neutron stars ( nss ) we separate short gamma - ray bursts ( grbs ) in two sub - classes . the ones with @xmath0 erg coalesce to form a massive ns and are indicated as short gamma - ray flashes ( s - grfs ) . the hardest , with @xmath1 erg , coalesce to form a black hole ( bh ) and are indicated as genuine short - grbs ( s - grbs ) . within the fireshell model , s - grbs exhibit three different components : the p - grb emission , observed at the transparency of a self - accelerating baryon-@xmath2 plasma ; the prompt emission , originating from the interaction of the accelerated baryons with the circumburst medium ; the high - energy ( gev ) emission , observed after the p - grb and indicating the formation of a bh . grb 090510 gives the first evidence for the formation of a kerr bh or , possibly , a kerr - newman bh . its p - grb spectrum can be fitted by a convolution of thermal spectra whose origin can be traced back to an axially symmetric dyadotorus . a large value of the angular momentum of the newborn bh is consistent with the large energetics of this s - grb , which reach in the @xmath3@xmath4 kev range @xmath5 erg and in the @xmath6@xmath7 gev range @xmath8 erg , the most energetic gev emission ever observed in s - grbs . the theoretical redshift @xmath9 that we derive from the fireshell theory is consistent with the spectroscopic measurement @xmath10 , showing the self - consistency of the theoretical approach . all s - grbs exhibit gev emission , when inside the _ fermi_-lat field of view , unlike s - grfs , which never evidence it . the gev emission appears to be the discriminant for the formation of a bh in grbs , confirmed by their observed overall energetics . . And you have already written the first three sentences of the full article: thanks to a fortunate coincidence of observations by agile , _ fermi _ , and _ swift _ satellites , together with the optical observations by the vlt / fors2 and the nordic optical telescope , it has been possible to obtain an unprecedented set of data , extending from the optical - uv , through the x - rays , all the way up to the high energy ( gev ) emission , which allowed detailed temporal / spectral analyses on grb 090510 @xcite . in contrast with this outstanding campaign of observations , a theoretical analysis of the broadband emission of grb 090510 has been advanced within the synchrotron / self - synchrotron compton ( ssc ) and traditional afterglow models ( see , e.g. , sections 5.2.1 and 5.2.2 in * ? ? ? * ) . paradoxically , this same methodology has been applied in the description of markedly different type of sources : e.g. , @xcite for the low energetic long grb 060218 , @xcite for the high energetic long grb 130427a , and @xcite for the s - grf 051221a . in the meantime , it has become evident that grbs can be subdivided into a variety of classes and sub - classes @xcite , each of them characterized by specific different progenitors which deserve specific theoretical treatments and understanding . in addition. Please generate the next two sentences of the article

every sub - class shows different episodes corresponding to specifically different astrophysical processes , which can be identified thanks to specific theoretical treatments and data analysis . in this article , we take grb 090510 as a prototype for s - grbs and perform a new time - resoved spectral analysis , in excellent agreement with the above temporal and spectral analysis performed by , e.g. , the _ fermi _ team . now this analysis , guided by a theoretical approach successfully tested in this new family of s - grbs @xcite , is directed to identify a precise sequence of different events made possible by the exceptional quality of the data of grb 090510 .

Suppose that you have an abstract for a scientific paper: electroweak precision data have been extensively used to constrain models containing physics beyond that of the standard model . when the model contains higgs scalars in representations other than singlets or doublets , and hence @xmath0 at tree level , a correct renormalization scheme requires more inputs than the three commonly used for the standard model case . in such cases , the one loop electroweak results can not be split into a standard model contribution plus a piece which vanishes as the scale of new physics becomes much larger than @xmath1 . we illustrate our results by presenting the dependence of @xmath1 on the top quark mass in a model with a higgs triplet and in the @xmath2 left - right symmetric model . in these models , the allowed range for the lightest neutral higgs mass can be as large as a few tev . . And you have already written the first three sentences of the full article: measurements at lep , sld , and the tevatron have been used extensively to limit models with physics beyond that of the standard model ( sm)@xcite . by performing global fits to a series of precision measurements , information about the parameters of new models can be inferred@xcite . the simplest example of this approach is the prediction of the @xmath3 boson mass . in the standard model , the @xmath3- boson mass , @xmath1 ,. Please generate the next two sentences of the article

can be predicted in terms of other parameters of the theory . the predicted @xmath3 boson mass is strongly correlated with the experimentally measured value of the top quark mass , @xmath4 , and increases quadratically as the top quark mass is increased .

Suppose that you have an abstract for a scientific paper: the passage of cold cesium 49s@xmath0 rydberg atoms through an electric - field - induced multi - level avoided crossing with nearby hydrogen - like rydberg levels is employed to prepare a cold , dipolar rydberg atom gas . when the electric field is ramped through the avoided crossing on time scales on the order of 100 ns or slower , the 49s@xmath0 population adiabatically transitions into high-_l _ rydberg stark states . the adiabatic state transformation results in a cold gas of rydberg atoms with large electric dipole moments . after a waiting time of about @xmath1s and at sufficient atom density , the adiabatically transformed highly dipolar atoms become undetectable , enabling us to discern adiabatic from diabatic passage behavior through the avoided crossing . we attribute the state - selectivity to @xmath2-mixing collisions between the dipolar atoms . the data interpretation is supported by numerical simulations of the passage dynamics and of binary @xmath2-mixing collisions . . And you have already written the first three sentences of the full article: atoms in highly excited rydberg states ( principal quantum number @xmath3 ) have large radii and electric - dipole transition matrix elements ( @xmath4 ) , large polarizabilities ( @xmath5 ) and strong van - der - waals interactions ( @xmath6 ) @xcite.these properties have led to a variety of interesting investigations and applications , including quantum information and logic gates @xcite , single - photon sources @xcite enabled by the rydberg excitation blockade effect @xcite , and many - body physics with strong long - range interactions @xcite . the large polarizability makes rydberg atoms sensitive to external fields , giving rise to applications in field measurement @xcite , quantum control @xcite and studies involving collisions @xcite and novel molecules @xcite . ( circles ) are prepared at an electric field @xmath7 = 3.14 v / cm .. Please generate the next two sentences of the article

the field is then linearly ramped to @xmath8 = 3.99 v / cm with a rise time @xmath9 across a selected avoided crossing . the rydberg atoms undergo adiabatic / diabatic passage through the avoided crossing .

Suppose that you have an abstract for a scientific paper: our aim in the present work is to develop approximations for the collisional dynamics of traveling waves in the context of granular chains in the presence of precompression . to that effect , we aim to quantify approximations of the relevant hertzian fpu - type lattice through both the korteweg - de vries ( kdv ) equation and the toda lattice . using the availability in such settings of both 1-soliton and 2-soliton solutions in explicit analytical form , we initialize such coherent structures in the granular chain and observe the proximity of the resulting evolution to the underlying integrable ( kdv or toda ) model . while the kdv offers the possibility to accurately capture collisions of solitary waves propagating in the same direction , the toda lattice enables capturing both co - propagating and counter - propagating soliton collisions . the error in the approximation is quantified numerically and connections to bounds established in the mathematical literature are also given . . And you have already written the first three sentences of the full article: granular crystals are material systems based on the assembly of particles in one- , two- and three - dimensions inside a matrix ( or a holder ) in ordered closely packed configurations in which the grains are in contact with each other @xcite . the fundamental building blocks constituting such systems are macroscopic particles of spherical , toroidal , elliptical or cylindrical shapes @xcite , arranged in different geometries . the mechanical , and more specifically dynamic , properties of these systems are governed by the stress propagation at the contact between neighboring particles .. Please generate the next two sentences of the article

this confers to the overall system a highly nonlinear response dictated , in the case of particles with an elliptical or spherical contact , by the discrete hertzian law of contact interaction @xcite . geometry and/or material anisotropy between particles composing the systems allows for the observation of interesting dynamic phenomena deriving from the interplay of discreteness and nonlinearity of the problem ( i.e. anomalous reflections , breathers , energy trapping and impulse fragmentation ) @xcite .

Suppose that you have an abstract for a scientific paper: we show that the centrality and system - size dependence of elliptic flow measured at rhic are fully described by a simple model based on eccentricity scaling and incomplete thermalization . we argue that the elliptic flow is at least 25% below the ( ideal ) `` hydrodynamic limit '' , even for the most central au - au collisions . this lack of perfect equilibration allows for estimates of the effective parton cross section in the quark - gluon plasma and of its viscosity to entropy density ratio . we also show how the initial conditions affect the transport coefficients and thermodynamic quantities extracted from the data , in particular the viscosity and the speed of sound . when two ultrarelativistic nuclei collide at non - zero impact parameter , their overlap area in the transverse plane has a short axis , parallel to the impact parameter , and a long axis perpendicular to it . this almond shape of the initial profile is converted by the pressure gradient into a momentum asymmetry , so that more particles are emitted along the short axis @xcite . the magnitude of this effect is characterized by elliptic flow , defined as @xmath0 where @xmath1 is the azimuthal angle of an outgoing particle , @xmath2 is the azimuthal angle of the impact parameter , and angular brackets denote an average over many particles and many events . the unexpected large magnitude of elliptic flow at rhic @xcite has generated a lot of activity in recent years . elliptic flow results from the interactions between the produced particles , and can be used to probe local thermodynamic equilibrium . if the produced matter equilibrates , it behaves as an ideal fluid . hydrodynamics predicts that at a given energy , @xmath3 scales like the eccentricity @xmath4 of the almond @xcite . it is independent of its transverse size @xmath5 , as a consequence of the scale invariance of ideal - fluid dynamics . if , on the other hand , equilibration is incomplete , then eccentricity scaling is broken and @xmath6 also.... And you have already written the first three sentences of the full article: j.y.o . thanks b. alver , a.h . mueller and d. schiff for helpful discussions . is supported through bmbf grant 05 cu5ri1/3 . j. y. ollitrault , phys .. Please generate the next two sentences of the article

d * 46 * , 229 ( 1992 ) . k. h. ackermann _ et al .

Suppose that you have an abstract for a scientific paper: we study the rotor - router walk on the infinite square lattice with the outgoing edges at each lattice site ordered clockwise . in the previous paper [ j.phys.a : math . theor . 48 , 285203 ( 2015 ) ] , we have considered the loops created by rotors and labeled sites where the loops become closed . the sequence of labels in the rotor - router walk was conjectured to form a spiral structure obeying asymptotically an archimedean property . in the present paper , we select a subset of labels called `` nodes '' and consider spirals formed by nodes . the new spirals are directly related to tree - like structures which represent the evolution of the cluster of vertices visited by the walk . we show that the average number of visits to the origin @xmath0 by the moment @xmath1 is @xmath2 where @xmath3 is the average number of rotations of the spiral . _ keywords _ : rotor - router walk , archimedean spiral , sub - diffusion . . And you have already written the first three sentences of the full article: the rotor mechanism , firstly proposed in the theory of self - organized criticality @xcite under name `` eulerian walk '' @xcite , was rediscovered independently as a tool for a derandomization of the random walk @xcite . the subsequent studies were concerned with collective properties of the medium `` organized '' by the walk and with statistical properties of the walk itself @xcite . the dynamics of the rotor - router walk can be described as follows .. Please generate the next two sentences of the article

consider a square lattice with arrows attached to the lattice sites . arrows attached to the lattice sites are directed toward one of their neighbors on the lattice .

Suppose that you have an abstract for a scientific paper: the density matrix of hawking radiation is calculated in the model of black hole with fluctuating horizon . quantum fluctuations smear the classical horizon of black hole and modify the density matrix of radiation producing the off - diagonal elements . the off - diagonal elements may store information of correlations between radiation and black hole . the smeared density matrix was constructed by convolution of the density matrix calculated with the instantaneous horizon with the gaussian distribution over the instantaneous horizons . the distribution has the extremum at the classical radius of the black hole and the width of order of the planck length . calculations were performed in the model of black hole formed by the thin collapsing shell which follows a trajectory which is a solution of the matching equations connecting the interior and exterior geometries . * density matrix of radiation of black hole with fluctuating horizon * * mikhail z. iofa * skobeltsyn institute of nuclear physics moscow state university moscow 119991 , russia . And you have already written the first three sentences of the full article: from the time of hawking s discovery that black holes radiate with the black - body radiation , the problem of information stored in a black hole @xcite attracted much attention . different ideas were discussed , in particular those of remnants @xcite , `` fuzziness '' of the black hole @xcite and refs . therein , quantum hair @xcite and refs.therein . , and smearing of horizon by quantum fluctuations @xcite .. Please generate the next two sentences of the article

the underlying idea of the last approach is that small fluctuations of the background geometry lead to corrections to the form of the density matrix of radiation . these corrections are supposed to account for correlations between the black hole and radiation and contain the imprint of information thrown into the black hole with the collapsing matter .

Suppose that you have an abstract for a scientific paper: an exp - algebraic curve consists of a compact riemann surface @xmath0 together with @xmath1 equivalence classes of germs of meromorphic functions modulo germs of holomorphic functions , @xmath2 , \cdots , [ h_n ] \}$ ] , with poles of orders @xmath3 at points @xmath4 . this data determines a space of functions @xmath5 ( respectively , a space of @xmath6-forms @xmath7 ) holomorphic on the punctured surface @xmath8 with exponential singularities at the points @xmath4 of types @xmath9 , \cdots , [ h_n]$ ] , i.e. , near @xmath10 any @xmath11 is of the form @xmath12 for some germ of meromorphic function @xmath13 ( respectively , any @xmath14 is of the form @xmath15 for some germ of meromorphic @xmath6-form ) . for any @xmath14 the completion of @xmath16 with respect to the flat metric @xmath17 gives a space @xmath18 obtained by adding a finite set @xmath19 of @xmath20 points , and it is known that integration along curves produces a nondegenerate pairing of the relative homology @xmath21 with the derham cohomology group defined by @xmath22 . there is a degree zero line bundle @xmath23 associated to an exp - algebraic curve , with a natural isomorphism between @xmath7 and the space @xmath24 of meromorphic @xmath23-valued @xmath6-forms which are holomorphic on @xmath16 , so that @xmath21 maps to a subspace @xmath25 . we show that the exp - algebraic curve @xmath26 is determined uniquely by the pair @xmath27 . [ section ] [ theorem]proposition [ theorem]lemma [ theorem]corollary [ theorem]definition . And you have already written the first three sentences of the full article: a choice of nonconstant meromorphic function @xmath28 on a compact riemann surface @xmath0 realizes @xmath0 as a finite sheeted branched covering of the riemann sphere @xmath29 . _ log - riemann surfaces of finite type _ are certain branched coverings , in a generalized sense , of @xmath30 by a punctured compact riemann surface , namely , which are given by certain transcendental functions of infinite degree .. Please generate the next two sentences of the article

formally a log - riemann surface consists of a riemann surface together with a local holomorphic diffeomorphism @xmath31 from the surface to @xmath30 such that the set of points @xmath19 added to the surface , in the completion @xmath18 with respect to the path - metric induced by the flat metric @xmath32 , is discrete . log - riemann surfaces were defined and studied in @xcite ( see also @xcite ) , where it was shown that the map @xmath31 restricted to any small enough punctured metric neighbourhood of a point @xmath33 in @xmath19 gives a covering of a punctured disc in @xmath30 , and is thus equivalent to either @xmath34 restricted to a punctured disc @xmath35 ( in which case we say @xmath33 is a ramification point of order @xmath1 ) or to @xmath36 restricted to a half - plane @xmath37 ( in which case we say @xmath33 is a ramification point of infinite order ) . a log - riemann surface is said to be of finite type if it has finitely many ramification points and finitely generated fundamental group .

Suppose that you have an abstract for a scientific paper: predator - prey relationships are one of the most studied interactions in population ecology . however , little attention has been paid to the possibility of role exchange between species once determined as predators and preys , despite firm field evidence of such phenomena in the nature . in this paper , we build a model capable of reproducing the main phenomenological features of one reported predator - prey role - reversal system , and present results for both the homogeneous and the space explicit cases . we find that , depending on the choice of parameters , our role - reversal dynamical system exhibits excitable - like behaviour , generating waves of species concentrations that propagate through space . . And you have already written the first three sentences of the full article: in 1988 , a. barkai and c.d mcquaid reported a novel observation in population ecology while studying benthic fauna in south african shores @xcite : a predator - prey role reversal between a decapod crustacean and a marine snail . specifically , in malgas island , the rock lobster _ jasus lalandii _ preys on a type of whelk , _ burnupena papyracea_. as could be easily expected , the population density of whelks soared upon extinction of the lobsters in a nearby island ( marcus island , just four kilometers away from malgas ) .. Please generate the next two sentences of the article

however , in a series of very interesting controlled ecological experiments , barkai and mcquaid reintroduced a number of _ jasus lalandii _ in marcus island , to investigate whether the equilibrium observed in the neighboring malgas island could be restored . the results were simply astounding : _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ `` the result was immediate .

Suppose that you have an abstract for a scientific paper: because of the lack of reliable sunspot observation , the quality of sunspot number series is poor in the late 18th century , leading to the abnormally long solar cycle ( 17841799 ) before the dalton minimum . using the newly recovered solar drawings by the 1819th century observers staudacher and hamilton , we construct the solar butterfly diagram , i.e. the latitudinal distribution of sunspots in the 1790 s . the sudden , systematic occurrence of sunspots at high solar latitudes in 17931796 unambiguously shows that a new cycle started in 1793 , which was lost in traditional wolf s sunspot series . this finally confirms the existence of the lost cycle that has been proposed earlier , thus resolving an old mystery . this letter brings the attention of the scientific community to the need of revising the sunspot series in the 18th century . the presence of a new short , asymmetric cycle implies changes and constraints to sunspot cycle statistics , solar activity predictions , solar dynamo theories as well as for solar - terrestrial relations . . And you have already written the first three sentences of the full article: starting from the first telescopic sunspot observations by david and johannes fabricius , galileo galilei , thomas harriot and christoph scheiner , the 400-year sunspot record is one of the longest directly recorded scientific data series , and forms the basis for numerous studies in a wide range of research such as , e.g. , solar and stellar physics , solar - terrestrial relations , geophysics , and climatology . during the 400-year interval , sunspots depict a great deal of variability from the extremely quiet period of the maunder minimum @xcite to the very active modern time @xcite . the sunspot numbers also form a benchmark data series , upon which virtually all modern models of long - term solar dynamo evolution , either theoretical or ( semi)empirical , are based .. Please generate the next two sentences of the article

accordingly it is important to review the reliability of this series , especially since it contains essential uncertainties in the earlier part . the first sunspot number series was introduced by rudolf wolf who observed sunspots from 1848 until 1893 , and constructed the monthly sunspot numbers since 1749 using archival records and proxy data @xcite .

Suppose that you have an abstract for a scientific paper: we discuss one of the most prominent features of the very recent preliminary elliptic flow data of @xmath0 meson from the phenix collaboration @xcite . even within the the rather large error bars of the measured data a negative elliptic flow parameter ( @xmath1 ) for @xmath0 in the range of @xmath2 is visible . we argue that this negative elliptic flow at intermediate @xmath3 is a clear and qualitative signature for the collectivity of charm quarks produced in nucleus - nucleus reactions at rhic . within a parton recombination approach we show that a negative elliptic flow puts a lower limit on the collective transverse velocity of heavy quarks . the numerical value of the transverse flow velocity @xmath4 for charm quarks that is necessary to reproduce the data is @xmath5 and therefore compatible with the flow of light quarks . the main goal of the current and past heavy ion programs is the search for a new state of matter called the quark - gluon - plasma ( qgp ) @xcite . major breakthroughs for the potential discovery @xcite of this new state of matter were the observation of constituent quark number scaling of the elliptic flow @xmath6 , with @xmath7 being the number of constituent quarks in the respective hadron as well as the observation of jet quenching at intermediate transverse momenta @xcite . together with the standard hydrodynamical interpretation this implies a rapid thermalization and a strong collective flow of the qcd matter created at rhic . however , open questions remain : how can one obtain a consistent description of the high @xmath3 suppression and the elliptic flow of heavy flavour quarks and hadrons . i.e. is the collectivity at rhic restricted to light quarks ( up , down , strange ) or do even charm ( bottom ) quarks participate in the collective expansion of the partonic system and reach local kinetic equilibrium ? previously , it was assumed that local equilibrium of ( heavy ) quarks could not be achieved within pqcd transport simulations . in fact , older.... And you have already written the first three sentences of the full article: this work was supported by gesellschaft fr schwerionenforschung , darmstadt ( gsi ) and by the loewe initiative of the state of hessen through the helmholtz international center for fair . s. a. bass , m. gyulassy , h. stoecker and w. greiner , j. phys . g * 25 * , r1 ( 1999 ) [ arxiv : hep - ph/9810281 ] .. Please generate the next two sentences of the article

k. adcox _ et al . _ [ phenix collaboration ] , nucl .