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Suppose that you have an abstract for a scientific paper: the basic question in the long - standing debate about free will ( fw ) is not whether fw can be demonstrated to exist nor even whether it exists , but instead how to define it scientifically .
if fw is not dismissed as an illusion nor identified with a variety of unpredictability , then logical paradoxes arise that make fw elusive to define .
we resolve these paradoxes through a model of fw , in which fw is a new causal primitive empowered to override physical causality under guidance .
we develop a simple mathematical realization of this model , that when applied to quantum theory , suggests that the exercise of fw corresponds to a nonlinear povm causing deviations from the born rule . in principle
, these deviations would stand in conflict with known conservation laws and invariance principles , implying that the brain , the presumed seat of fw , may be an arena of non - standard physics .
however , in practice it will be difficult to distinguish these deviations from quantum and neural noise , and statistical fluctuations .
we indicate possible neurobiological and neurological tests , implications and applications of our proposed model . .
And you have already written the first three sentences of the full article: free will ( fw ) , as we informally understand it in daily life , is the power of a rational agent to pick her / his own choice from among various alternative possbilities .
but what exactly is fw ?
the age - old question has provoked much debate among philosophers and scientists @xcite ..
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our outlook on the world implicitly assumes that human behavior is governed by fw : we choose , we plan and we normally hold people responsible for what they say or do , either because we imagine that they are at liberty also not to act so , or because we do nt have the freedom to believe otherwise ! neuroscience has been uncovering causal chains that appear to explain our choices , emotions and even beliefs , in terms of neurophysical events extending back to the pre - natal stage . as much as it is interesting and important to understand whether we have fw
, there is a more elementary and pressing problem to deal with : namely to try to define fw rigorously and scientifically in a way that agrees with the above intuitive notion .
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Suppose that you have an abstract for a scientific paper: we report on the mid - infrared imaging at 5 , 7 , 10 & 15 @xmath0 m of the galaxy cluster abell 2218 obtained with the isocam instrument onboard esa s infrared space observatory ( iso ) , as part of an on - going program to image gravitational arcs and arclets in distant clusters .
several cluster galaxies as well as field galaxies are detected .
we discuss their mid - ir flux properties . .
And you have already written the first three sentences of the full article: abell 2218 is a very rich galaxy cluster ( richness class 4 , according to abell et al .
1989 ) , characterized by a large velocity dispersion of the galaxy population ( @xmath1 km / s , le borgne et al .
1992 ) , and a high x - ray temperature and luminosity ( @xmath2 kev , see e.g. markevitch 1997 , @xmath3 erg / s km / s / mpc and @xmath4 in the energy band 0.54.4 kev , see e.g. kneib et al ..
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1996 ) . these properties , coupled to a relatively small distance ( @xmath5 , le borgne et al .
1992 ) , made this cluster an attractive target for studies of the sunyaev - zeldovich effect ( birkinshaw & hughes 1994 ) , and one of the closest clusters where gravitational arcs are detected .
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Suppose that you have an abstract for a scientific paper: we present a summary of our recent results on gas outflows in radio galaxies .
fast outflows ( up to 2000 @xmath0km@xmath0s@xmath1 ) have been detected both in ionized and neutral gas .
the latter is particularly surprising as it shows that , despite the extremely energetic phenomena occurring near an agn , some of the outflowing gas remains , or becomes again , neutral .
these results are giving new and important insights on the physical conditions of the gaseous medium around an agn .
# 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: fast nuclear gas outflows appear to be a relatively common phenomena in active galactic nuclei ( agns ) . they have been detected - using optical , uv and x - ray observations - in seyfert galaxies ( see for some examples crenshaw et al .
2000 ; aoki et al . 1996 ; capetti et al . 1999 and
refs therein ) , quasars ( see e.g. turnshek 1986 , krongold et al.2003 and refs therein ) , but also in starburst galaxies ( veilleux et al ..
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2002 , 2003 ) .
these gas outflows can have different origins , such as being jet - driven ( if the object is radio loud ) or related to starburst and agn winds .
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Suppose that you have an abstract for a scientific paper: for @xmath0 and @xmath1 a simple connected graph , a @xmath2-radio labeling @xmath3 of @xmath1 requires all pairs of distinct vertices @xmath4 and @xmath5 to satisfy @xmath6 . when @xmath7 , this requirement gives rise to the familiar labeling known as vertex coloring for which each vertex of a graph is labeled so that adjacent vertices have different colors " .
we consider @xmath2-radio labelings of @xmath1 when @xmath8 . in this
setting , no two vertices can have the same label , so graphs that have radio labelings of consecutive integers are one extreme on the spectrum of possibilities .
examples of such graphs of high diameter are especially rare and desirable .
we construct examples of arbitrarily high diameter , and explore further the tool we used to do this the cartesian product of graphs and its effect on radio labeling . .
And you have already written the first three sentences of the full article: a radio labeling of a graph is a generalization of vertex coloring . given a graph @xmath1 ( for us
, @xmath1 is simple and connected ) with vertex set @xmath9 , any function @xmath3 is a labeling of the vertices .
if that labeling satisfies the inequality @xmath10 for all distinct vertices @xmath11 , then @xmath12 is a coloring of @xmath1 ..
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this inequality is exactly the condition needed to guarantee that adjacent vertices are labeled with a different color " .
we can generalize this notion of graph coloring by changing the inequality to the following : @xmath13 for some @xmath14 , @xmath15 . a labeling satisfying this inequality for all vertices
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Suppose that you have an abstract for a scientific paper: we take an existing implementation of an algorithm for the maximum clique problem and modify it so that we can distribute it over an ad - hoc cluster of machines .
our goal was to achieve a significant speedup in performance with minimal development effort , i.e. a _
maximum costup_. we present a simple modification to a state - of - the - art exact algorithm for maximum clique that allows us to distribute it across many machines .
an empirical study over large hard benchmarks shows that speedups of an order of magnitude are routine for 25 or more machines . .
And you have already written the first three sentences of the full article: intel s tera - scale computing vision ( _ a parallel path to the future _ ) is to aim for hundreds of cores on a chip . in their white paper
@xcite intel puts `` programmability '' at the top of the list of challenges for the multi - core era , and considers the development of multi - core software to be amongst the greatest challenges for tera - scale computing .
however , hill and marty @xcite propose that in exploiting multi - cores we should not just aim for _ speedup _ but also _ costup _ , i.e. an increase in performance that is greater than the increase in cost , be it measured in money or energy . and that is our target , to maximise costup ..
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we were presented with the following challenge .
the second author had just completed an empirical study of exact algorithms for the maximum clique problem and a variety of algorithms had been implemented in java @xcite .
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Suppose that you have an abstract for a scientific paper: we consider two driven cavities ( capacitors ) connected in series via an edge state .
the cavities are driven such that they emit an electron and a hole in each cycle .
depending on the phase lag the second cavity can effectively absorb the carriers emitted by the first cavity and nullify the total current or the set - up can be made to work as a two - particle emitter .
we examine the precision with which the current can be nullified and with which the second cavity effectively counts the particles emitted by the first one . to achieve single - particle detection we examine pulsed cavities . .
And you have already written the first three sentences of the full article: the dynamics of a quantum coherent capacitor connected via a single contact to an electron reservoir have attracted experimental and theoretical interest .
a capacitor connected via a quantum point contact ( qpc ) to an edge state shows mesoscopic capacitance oscillations and a quantized charge relaxation resistance @xcite .
in addition a recent experiment demonstrated an `` electron gun '' emitting and absorbing a single electron in every oscillation cycle @xcite ..
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the emission process @xcite injects an electron into states above the fermi level , whereas absorption of an electron leaves a hole below the fermi energy .
the invention of lasers revolutionized optics .
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Suppose that you have an abstract for a scientific paper: ' '' '' we use standard distorted wave theory techniques and dimensional regularization to find out solutions of the nucleon - nucleon lippman schwinger equation with a potential that includes one pion exchange and additional contact terms with derivatives . though for simplicity , we restrict the discussion to the @xmath0 channel and to contact terms containing up to two derivatives , the generalization to higher waves and/or number of derivatives is straightforward .
the undetermined low energy constants emerging out of the renormalization procedure are fitted to data . .
And you have already written the first three sentences of the full article: over the last years , effective field theory ( eft ) methods have become the standard tool to deal with strong interactions in the non - perturbative regime . in the form of chiral perturbation theory ( chpt ) , they have been used with some success in both the mesonic and single nucleon sectors .
the eft of nuclear forces based on a chiral expansion was originally suggested by weinberg @xcite , and since then a lot of work has been devoted to gain a better understanding of the two - nucleon interaction at low and intermediate energies @xcite@xcite .
while at the beginning , these studies did not aim at substituting the highly successful _ realistic _.
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potentials built from meson exchanges ( bonn - jlich , nijmegen , argonne , @xmath1 potentials ) , the importance of uncovering such an eft can not be ignored , since this theory will allow for rigorous calculations of both elastic and inelastic processes in systems with two or more nucleons , in a framework consistent with the standard model of strong and electroweak interactions .
furthermore , the latter eft works provide an accurate description of nucleon - nucleon ( nn ) phase - shifts for several partial waves and in a wide range of energies @xcite .
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Suppose that you have an abstract for a scientific paper: we investigate an array of identical phase oscillators non - locally coupled without time delay , and find that chimera state with two coherent clusters exists which is only reported in delay - coupled systems previously .
moreover , we find that the chimera state is not stationary for any finite number of oscillators .
the existence of the two - cluster chimera state and its time - dependent behaviors for finite number of oscillators are confirmed by the theoretical analysis based on the self - consistency treatment and the ott - antonsen ansatz . .
And you have already written the first three sentences of the full article: an array of identical oscillators has been used to model a wide range of systems , such as neural networks , convecting fluids , laser arrays and coupled biochemical oscillators .
these systems exhibit rich collective behaviors including synchrony and spatiotemporal chaos @xcite .
most of the earlier theoretical works on these systems assume either local coupling ( nearest - neighbor interactions ) or global coupling ( infinite - range interactions ) ; a third type named non - locally coupling began to be explored in the past years , which is somewhere between local coupling and global coupling ..
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in non - local coupled systems , the oscillators interact with all others and the strength between oscillators varies with the distance between them .
chimera state is a spatiotemporal pattern in which some of the identical oscillators are coherent and synchronous while others remain incoherent @xcite .
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Suppose that you have an abstract for a scientific paper: we present parsec scale interferometric maps of hcn(1 - 0 ) and hco@xmath0(1 - 0 ) emission from dense gas in the star - forming region 30 doradus , obtained using the australia telescope compact array .
this extreme star - forming region , located in the large magellanic cloud ( lmc ) , is characterized by a very intense ultraviolet ionizing radiation field and sub - solar metallicity , both of which are expected to impact molecular cloud structure .
we detect 13 bright , dense clumps within the 30 doradus-10 giant molecular cloud .
some of the clumps are aligned along a filamentary structure with a characteristic spacing that is consistent with formation via the varicose fluid instability .
our analysis shows that the filament is gravitationally unstable and collapsing to form stars .
there is a good correlation between hco@xmath0 emission in the filament and signatures of recent star formation activity including h@xmath1o masers and young stellar objects ( ysos ) .
ysos seem to continue along the same direction of the filament toward the massive compact star cluster r136 in the southwest .
we present detailed comparisons of clump properities ( masses , linewidths , sizes ) in 30dor-10 to those in other star forming regions of the lmc ( n159 , n113 , n105 , n44 ) .
our analysis shows that the 30dor-10 clumps have similar mass but wider linewidths and similar hcn / hco@xmath0 ( 1 - 0 ) line ratios as clumps detected in other lmc star - forming regions .
our results suggest that the dense molecular gas clumps in the interior of 30dor-10 are well - shielded against the intense ionizing field that is present in the 30doradus region . .
And you have already written the first three sentences of the full article: throughout the years many studies on galactic star formation have been conducted ( e.g. kennicutt & evans 2009 ; mckee & ostriker 2007 ; zinnecker & yorke 2007 ) .
it has been observed and theorized that within giant molecular clouds ( gmcs ) there are clumps and small cores .
this resulted in the idea that gmcs are hierarchical in nature with substructures spanning a large range of sizes ..
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clumps are dense regions with masses @xmath210@xmath3 - 10@xmath4m@xmath5 and sizes of a few parsec , whereas cores are smaller ( @xmath20.1pc ) and denser .
it is here where individual star formation occurs ( williams et al .
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Suppose that you have an abstract for a scientific paper: the weak kaon production off the nucleon induced by neutrinos and antineutrinos is studied at low and intermediate energies of interest for some ongoing and future neutrino oscillation experiments .
we develop a microscopical model based on the su(3 ) chiral lagrangians .
the studied mechanisms are the main source of kaon production for neutrino energies up to 2 gev for the various channels and the cross sections are large enough to be amenable to be measured by experiments such as minerva , t2k and no@xmath0a . .
And you have already written the first three sentences of the full article: neutrino physics has become one of the important areas of intense theoretical and experimental efforts .
this is because neutrinos are instrumental in giving answer to some of the basic questions in cosmology , astro- , nuclear , and particle physics .
the @xmath1 scattering processes have been studied by several authors for the quasielastic , 1 pion production and for deep - inelastic scattering processes @xcite-@xcite . however , there are very few works where neutrino induced strange particle production have been been studied @xcite-@xcite ..
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these processes are important for the analysis of the precise determination of neutrino oscillation parameters . in the few - gev region
it allows the detailed study of the strange - quark content of the nucleon and gives some important information about the structure of the hadronic weak current .
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Suppose that you have an abstract for a scientific paper: experimental results for covalent glasses have highlighted the existence of a new self - organized phase due to the tendency of glass networks to minimize internal stress .
recently , we have shown that an equilibrated self - organized two - dimensional lattice - based model also possesses an intermediate phase in which a percolating rigid cluster exists with a probability between zero and one , depending on the average coordination of the network . in this paper
, we study the properties of this intermediate phase in more detail .
we find that microscopic perturbations , such as the addition or removal of a single bond , can affect the rigidity of macroscopic regions of the network , in particular , creating or destroying percolation .
this , together with a power - law distribution of rigid cluster sizes , suggests that the system is maintained in a critical state on the rigid / floppy boundary throughout the intermediate phase , a behavior similar to self - organized criticality , but , remarkably , in a thermodynamically equilibrated state .
the distinction between percolating and non - percolating networks appears physically meaningless , even though the percolating cluster , when it exists , takes up a finite fraction of the network .
we point out both similarities and differences between the intermediate phase and the critical point of ordinary percolation models without self - organization .
our results are consistent with an interpretation of recent experiments on the pressure dependence of raman frequencies in chalcogenide glasses in terms of network homogeneity . .
And you have already written the first three sentences of the full article: the concept of rigidity percolation , first introduced about 25 years ago by thorpe @xcite based on work by phillips @xcite , describes how an elastic network goes from floppy to rigid as constraints are added to it .
this theory has been applied with success to many systems , including covalent glasses @xcite and proteins @xcite . in the last decade , however , experimental studies have shown that the rigidity phase diagram could be more complex than initially thought , uncovering the presence of an intermediate phase between the floppy phase and the stressed - rigid phase , with the system in the intermediate phase being rigid but unstressed @xcite . a basic explanation for this new phase was first proposed by thorpe _
et al . _.
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it was shown that when the network self - organizes in order to minimize the stress , the rigid but unstressed intermediate phase can indeed arise . in the original work by thorpe and collaborators @xcite , as well as subsequent simplified models of chalcogenide glasses by micoulaut and phillips @xcite
, networks were constructed using an `` aggregation '' process , in which bonds or simple network units were added to the network without subsequent equilibration .
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Suppose that you have an abstract for a scientific paper: we use homogeneous samples of radio - quiet seyfert 1 galaxies and qsos selected from the sloan digital sky survey to investigate the connection between the velocity shift and the equivalent width ( ew ) of the [ oiii]@xmath0 emission line , and their correlations with physical parameters of active galactic nuclei ( agns ) . we find a significant and negative correlation between the ew of the core component , ew(core ) , and the blueshift of either the core ( the peak ) , the wing , or the total profile of [ oiii ] emission ; it is fairly strong for the blueshift of the total profile particularly
. however , both quantities ( ew and velocity shift ) generally have only weak , if any , correlations with fundamental agn parameters such as the nuclear continuum luminosity at 5100 ( @xmath1 ) , black hole mass ( @xmath2 ) , and the eddington ratio ( @xmath3 ) ; these correlations include the classical baldwin effect of ew(core ) , an inverse baldwin effect of ew(wing ) , and the relationship between velocity shifts and @xmath3 .
our findings suggest that both the large object - to - object variation in the strength of [ oiii ] emission and the blueshift
ew(core ) connection are not governed primarily by fundamental agn parameters such as @xmath1 , @xmath2 and @xmath3 .
we propose that the ism conditions of the host galaxies play a major role instead in the diversity of the [ oiii ] properties in active galaxies .
this suggests that the use of [ oiii]@xmath0 luminosity as proxy of agn luminosity does not depend strongly on the above - mentioned fundamental agn parameters . .
And you have already written the first three sentences of the full article: in terms of size , the narrow - line region ( nlr ) of active galactic nuclei ( agns ; including seyfert galaxies and quasars ) represents the link between the inner structure of the agn the dusty torus and the broad - line region ( blr)and the interstellar medium in the host galaxy .
the nlr bridges the region dominated by the gravitational field of the central massive black hole and the region dominated by the gravitational potential of the bulge stars of the host galaxy . to gain a complete understanding of the agn phenomenon , the role of the nlr therefore needs to be understood . unlike the blr , the nlr , or at least the outer parts of the nlr , can be spatially resolved in nearby agns . despite this
, however , the nlr remains remarkably poorly understood and there are many unanswered questions about the structure and kinematics of the nlr and its relationship to the blr / torus ..
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[ oiii]@xmath0 is one of the most important nlr lines .
its equivalent width ( ew ) in the agn ensemble varies dramatically by a factor of @xmath4 ( from @xmath5 to 157 ; baskin & laor 2005b ) , one of the things showing the most object - to - object variation in agns .
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Suppose that you have an abstract for a scientific paper: one of the mechanisms widely considered for driving relativistic jets in active galactic nuclei , galactic microquasars , and gamma - ray bursts is the electromagnetic extraction of the rotational energy of a central black hole , i.e. , the blandford - znajek process , although the origin of the electromotive force in this process is still under debate .
we study this process as the steady unipolar induction in the kerr black hole magnetosphere filled with a collisionless plasma screening the electric field ( the @xmath0 field ) along the magnetic field ( the @xmath1 field ) , i.e. , @xmath2 = 0 .
we extend the formulations and arguments made by komissarov , and generally show that the origin of the electromotive force is ascribed to the ergosphere .
it is explicitly shown that open magnetic field lines penetrating the ergosphere have a region where the @xmath0 field is stronger than the @xmath1 field in the ergosphere , and it keeps driving the poloidal currents and generating the electromotive force and the outward poynting flux .
the range of the possible value of the so - called angular velocity of the magnetic field line @xmath3 is deduced for the field lines threading the equatorial plane in the ergosphere .
we briefly discuss the relation between our conclusion and the ideal magnetohydrodynamic condition .
[ firstpage ] black hole physics magnetic fields relativistic processes . .
And you have already written the first three sentences of the full article: collimated outflows , or jets , with relativistic speeds are observed in active galactic nuclei and galactic microquasars , and are presumably driven in gamma - ray bursts .
possible mechanisms for driving relativistic jets include the electromagnetic extraction of the rotational energy of a central black hole ( bh ) @xcite , the electromagnetic extraction of the rotational energy of an accretion flow around a bh @xcite , and the thermal gas ejection from an accretion flow ( e.g. , * ? ? ?
* ; * ? ? ?.
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* ; * ? ? ?
* ; * ? ? ?
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Suppose that you have an abstract for a scientific paper: initial - boundary value problems for integrable nonlinear partial differential equations have become tractable in recent years due to the development of so - called unified transform techniques .
the main obstruction to applying these methods in practice is that calculation of the spectral transforms of the initial and boundary data requires knowledge of too many boundary conditions , more than are required make the problem well - posed .
the elimination of the unknown boundary values is frequently addressed in the spectral domain via the so - called global relation , and types of boundary conditions for which the global relation can be solved are called _ linearizable_. for the defocusing nonlinear schrdinger equation , the global relation is only known to be explicitly solvable in rather restrictive situations , namely homogeneous boundary conditions of dirichlet , neumann , and robin ( mixed ) type .
general nonhomogeneous boundary conditions are not known to be linearizable . in this paper
, we propose an explicit approximation for the nonlinear dirichlet - to - neumann map supplied by the defocusing nonlinear schrdinger equation and use it to provide approximate solutions of general nonhomogeneous boundary value problems for this equation posed as an initial - boundary value problem on the half - line .
our method sidesteps entirely the solution of the global relation .
the accuracy of our method is proven in the semiclassical limit , and we provide explicit asymptotics for the solution in the interior of the quarter - plane space - time domain . .
And you have already written the first three sentences of the full article: consider the following initial - boundary value problem for the defocusing nonlinear schrdinger equation on the positive half - line @xmath0 with given initial data : @xmath1 and with a given ( generally nonhomogeneous ) dirichlet boundary condition at @xmath2 : @xmath3 here @xmath4 is an arbitrary parameter . assuming that @xmath5 , @xmath6 , and that the compatibility condition @xmath7 holds , carroll and bu @xcite have established the existence of a unique classical global solution of this problem that is a continuously differentiable map from @xmath8 to @xmath9 and that is a continuous map from @xmath10 to @xmath11 .
the defocusing nonlinear schrdinger equation is an integrable equation , being the compatibility condition for the existence of a simultaneous general solution @xmath12 of the equation @xmath13 and also of the equation @xmath14 here @xmath15 is a complex spectral parameter , and the compatibility condition is independent of @xmath15 .
these two linear equations for @xmath12 comprise the _ lax pair _ for ..
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one of the earliest applications of the lax pair representation of integrable equations was the development of a transform technique based on the spectral theory of the spatial equation of the lax pair , the _ inverse - scattering transform _ , for solving initial - value problems posed for @xmath16 with initial data given at @xmath17 ; see @xcite for a pedagogical description .
more recently , a _ unified transform method _ has been developed involving the simultaneous use of both equations of the lax pair to study mixed initial - boundary value problems of various types . as a general reference for these methods that includes the specific details we will need in this paper , we refer to @xcite ;
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Suppose that you have an abstract for a scientific paper: absorption spectra toward herschel 36 for the _ _
__@xmath0 @xmath1 _ _ x__@xmath2 transitions of ch@xmath3 in the @xmath4 = 1 excited rotational level and the _ _
__@xmath5 @xmath1 _ _ x__@xmath6 transition of ch in the @xmath4 = 3/2 excited fine structure level have been analyzed .
these excited levels are above their ground levels by 40.1 k and @xmath7 25.7 k and indicate high radiative temperatures of the environment , 14.6 k and 6.7 k , respectively .
the effect of the high radiative temperature is more spectacular in some diffuse interstellar bands ( dibs ) observed toward her 36 ; remarkable extended tails toward red ( etr ) were observed .
we interpret these etrs as due to a small decrease of rotational constants upon excitation of the excited electronic states . along with radiative pumping of a great many high-@xmath4 rotational levels
, this causes the etrs . in order to study this effect
quantitatively , we have developed a model calculation in which the effects of collision and radiation are treated simultaneously .
the simplest case of linear molecules is considered .
it has been found that the etr is reproduced if the fraction of the variation of the rotational constant , @xmath8 @xmath9 , is sufficiently high ( 3 @xmath10 5% ) and the radiative temperature is high ( @xmath11 @xmath12 50 k ) .
although modeling for general molecules is beyond the scope of this paper , the results indicate that the prototypical dibs @xmath135780.5 , @xmath135797.1 , and @xmath136613.6 which show the pronounced etrs are due to polar molecules sensitive to the radiative excitation .
the requirement of high @xmath8 favors relatively small molecules with 3 - 6 heavy atoms . dibs @xmath135849.8 , @xmath136196.0 , and @xmath136379.3 which do not show the pronounced etrs are likely due to non - polar molecules or large polar molecules with small @xmath8 . .
And you have already written the first three sentences of the full article: since their discovery ( heger 1922 ) , the diffuse interstellar bands ( dibs ) have been a persistent spectroscopic enigma representing unidentified ingredients in the physics and chemistry of the interstellar medium .
the dibs are ubiquitous in the ism with the strongest clearly visible toward even lightly reddened stars though their relative strengths can vary in different sight lines ( e.g. , kreowski & walker 1987 ) .
recent deep surveys have catalogued at least 540 dibs , to equivalent width limits of several m , in two sight lines with @xmath14(@xmath15 ) @xmath7 1.1 ( hobbs et al ..
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2008 , 2009 ) .
while the dibs are likely molecular in origin , attempts to identify specific carrier molecules by comparing interstellar spectra with laboratory spectra of various candidates have been unsuccessful ( e.g. , snow & mccall 2006 ; salama et al .
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Suppose that you have an abstract for a scientific paper: we develop a new theory for treating boundary problems for linear ordinary differential equations whose fundamental system may have a singularity at one of the two endpoints of the given interval .
our treatment follows an algebraic approach , with ( partial ) implementation in the theorema software system ( which is based on mathematica ) .
we study an application to graded kirchhoff plates for illustrating a typical case of such boundary problems .
boundary problems , singular boundary problems , generalized green s operator , green s functions , integro - differential operators , ordinary differential equations , kirchhoff plates , functionally graded materials .
And you have already written the first three sentences of the full article: the treatment of boundary problems in symbolic computation was initiated in the phd thesis @xcite under the guidance of bruno buchberger in cooperation with heinz engl ; see also @xcite and for the further development @xcite .
its implementation was originally carried out within the th@xmath0orem@xmath1project @xcite . up to now
, we have always assumed differential equations without singularity or , equivalently , monic differential operators ( leading coefficient function being unity ) . in this paper.
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, we develop for the first time an _ algebraic theory _ for treating boundary problems with a ( mild ) _ singularity at one endpoint_. for details , we refer to section [ sec : bp - one - sing ] .
our approach is very different from the traditional analysis setting in terms of the weyl - titchmarsh theory ( limit points and limit circles ) .
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Suppose that you have an abstract for a scientific paper: frank - kasper ( f - k ) phases form an important set of large - cell crystalline structures describing many inter - metallic alloys . they are usually described in term of their atomic environments , with atoms having @xmath0 and @xmath1 neighbours , coded into the canonical @xmath2 cells ( with @xmath3 the coordination number ) , the case @xmath4 corresponding to a local icosahedral environment . in addition , the long range structure is captured by the geometry of a network ( called either `` major skeleton '' or `` disclination network '' ) connecting only the non - icosahedral sites ( with @xmath5 ) .
another interesting description , valid for the so - called `` layered f - k phases '' , amounts to give simple rules to decorate specific periodic 2d tilings made of triangles and squares and eventually get the 3d periodic f - k phases .
quasicrystalline phases can sometime be found in the vicinity , in the phase diagram , of the f - k crystalline alloys ; it is therefore of interest to understand if and how the standard f - k construction rules can be generalized on top of an underlying quasiperiodic structure .
it is in particular natural to investigate how well square - triangle quasiperiodic tilings with dodecagonal symmetry , made of square and ( equilateral ) triangles , can be used as building frames to generate some f - k - like quasicrystalline structures .
we show here how to produce two types of such structures , which are quasiperiodic in a plane and periodic in the third direction , and containing ( or not ) @xmath6 sites .
_ it is a pleasure for us to contribute to a special issue of `` structural chemistry '' in honour of alan mackay , for his 90th birthay .
alan s work has been a source of inspiration for most of the researchers working in the field of complex atomic structures . _ to appear in `` structural chemistry '' . .
And you have already written the first three sentences of the full article: beside simple metallic systems found with b.c.c and f.c.c structures , with few atoms per unit cells , many intermetallic alloys display more or less intricate structures with polytetrahedral type of packing , and possibly a large number of atoms in the unit cell , like in the so - called frank - kasper ( f - k ) phases@xcite . it is standard in that case to focus on the local atomic environments , the canonical @xmath2 cells ( see fig . [
fig : f1 ] ) , the case @xmath4 corresponding to a local icosahedral environment .
a long - standing question in quasicrystal studies is to relate the atomic order present in quasicrystalline phases with that of f - k phases , some of which being identified as rational approximants of the former ; dually , these quasicrystalline phases ( close in the phase diagram ) could then be thought as mere quasperiodic generalizations of the periodic f - k phases ..
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the four main frank - kasper coordination polyhedra ( top figure ) @xmath7 , @xmath8 , @xmath9 and @xmath6 , represented also by their voronoi cells ( lower figures ) . frank - kasper lines ( or disclination lines ) , shown as black lines , start from the center of the coordination polyhedra and run through the black sites , or from the voronoi cell centres and go through hexagonal faces , defining a `` major skeleton '' in the structure . ]
as will be detailed below , f - k structures can also be generated with an atomic decoration procedure applied on top of a plane tiling made of triangles and/or squares , building simple atomic layers .
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Suppose that you have an abstract for a scientific paper: we present linear polarization observations of the exoplanet system hd 189733 made with the high precision polarimetric instrument ( hippi ) on the anglo - australian telescope ( aat ) .
the observations have higher precision than any previously reported for this object .
they do not show the large amplitude polarization variations reported by @xcite .
our results are consistent with polarization data presented by @xcite .
a formal least squares fit of a rayleigh - lambert model yields a polarization amplitude of 29.4 @xmath0 15.6 parts - per - million .
we observe a background constant level of polarization of @xmath1 5570 ppm , which is a little higher than expected for interstellar polarization at the distance of hd 189733 .
[ firstpage ] polarization techniques : polarimetric planets and satellites : atmospheres planets and satellites : individual : hd 189733b .
And you have already written the first three sentences of the full article: the characterisation of exoplanet atmospheres , particularly with ground based telescopes , is a difficult task .
polarimetry offers a useful approach , providing a strong contrast between the star and planet as the star s light is typically unpolarized @xcite .
large and tightly orbiting hot jupiter planets scatter enough light to potentially produce a polarisation signal dependent largely upon the composition of the atmosphere @xcite ..
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the detection of linearly polarized light from an exoplanet system can provide information about a planet s orbital orientation and about the properties of the particles that scatter the light in its atmosphere .
the technique therefore provides complementary information to other characterisation techniques such as transit and eclipse spectroscopy .
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Suppose that you have an abstract for a scientific paper: the vast majority of pulsars detected by the _ fermi
_ large area telescope ( lat ) display exponentially cutoff spectra with cutoffs falling in a narrow band around a few gev .
early spectral modelling predicted spectral cutoffs at energies of up to 100 gev , assuming curvature radiation .
it was therefore not expected that pulsars would be visible in the very - high energy ( vhe ) regime ( @xmath0 gev ) .
the _ veritas _ announcement of the detection of pulsed emission from the crab pulsar at energies up to @xmath1 gev ( and now up to 1.5 tev as detected by _
magic _ ) therefore raised important questions about our understanding of the electrodynamics and local environment of pulsars .
_ h.e.s.s .
_ has now detected pulsed emission from the vela pulsar down to tens of gev , making this the second pulsar detected by a ground - based cherenkov telescope .
deep upper limits have also been obtained by _ veritas _ and _ magic _ for the geminga pulsar .
we will review the latest developments in vhe pulsar science , including an overview of the latest observations , refinements , and extensions to radiation models and magnetic field structures , and the implementation of new radiation mechanisms .
this will assist us in understanding the vhe emission detected from the crab pulsar , and predicting the level of vhe emission expected from other pulsars , which is very important for the upcoming _ .
And you have already written the first three sentences of the full article: since the launch in june 2008 of _ fermi _ lat @xcite , a high - energy ( he ) satellite measuring @xmath2-rays in the range 20 mev@xmath3300 gev , two pulsar catalogues ( 1pc , @xcite ; 2pc , @xcite ) discussing the light curve and spectral properties of 117 pulsars have been released . the vast majority of the _ fermi_-detected pulsars display exponentially cutoff spectra with cutoffs around a few gev .
these spectra are believed to be due to curvature radiation ( cr ) , which is assumed to be the dominating emission process in the gev band ( see section [ subsection : radiationmechanisms ] ) . there
exist several physical radiation models that can be used to study he emission from pulsars ..
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these include the polar cap ( pc ; @xcite ) , slot gap ( sg ; @xcite ) , outer gap ( og ; @xcite ) , and the pair - starved polar cap ( pspc ; @xcite ) models , which can be distinguished from each other based on the different assumptions of the geometry and location of the ` gap regions ' .
the ` gap region ' is where particle acceleration takes place due to an unscreened , rotation - induced @xmath4-field parallel to the local @xmath5-field , as well as subsequent emission by these particles . in pc models emission from he particles
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Suppose that you have an abstract for a scientific paper: the suppression of high-@xmath0 particles in heavy ion collisions was one of the key discoveries at the relativistic heavy ion collider .
this is usually parameterized by the average rate of momentum - transfer squared to this particle , @xmath1 . here
we argue that measurements of identified particles at high @xmath0 can lead to complementary information about the medium .
the leading particle of a jet can change its identity through interactions with the medium .
tracing such flavor conversions could allow us to constrain the mean free path . here
we review the basic concepts of flavor conversions and discuss applications to particle ratios and elliptic flow .
we make a prediction that strangeness is enhanced at high @xmath0 at rhic energies while its elliptic flow is suppressed . for the past decade
high momentum particles and jets have been used to probe the quark gluon plasma ( qgp ) phase created at the relativistic heavy ion collider ( rhic ) .
the energy loss of a fast parton suffered in the medium carries information about the typical momentum transfer @xmath2 along the path , more precisely about the transport coefficient @xmath3 @xcite .
we have recently argued that the mean free path @xmath4 of a fast parton could be determined separately by measuring the change in hadro - chemistry induced by the medium @xcite .
here we discuss a model based on conversions of the leading particle of a jet .
just as partons can lose energy through collisions and induced radiation , they can scatter through channels in which the identity of the fastest parton in the initial and final state are not the same .
examples are binary collisions like @xmath5 or @xmath6 which can lead to conversions of quarks into gluons and vice versa . here
the first parton on each side has a large momentum ( the leading jet parton ) and the second parton in the initial state is a thermal parton from the quark gluon plasma .
the rate of flavor conversions depends on the mean free path @xmath4 of fast....
And you have already written the first three sentences of the full article: we acknowledge support by the riken / bnl research center and doe grant de - ac02 - 98ch10886 .
r. baier , y. l. dokshitzer , a. h. mueller , s. peigne and d. schiff , nucl .
b * 483 * , 291 ( 1997 ) ; nucl ..
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b * 484 * , 265 ( 1997 ) .
b. g. zakharov , jetp lett .
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Suppose that you have an abstract for a scientific paper: let @xmath0 be the sequence of partial sums of normalized dini functions @xmath1 where @xmath2 .
the aim of the present paper is to obtain lower bounds for @xmath3 @xmath4 @xmath5 and @xmath6 .
also we give a few geometric description regarding image domains of some functions . .
And you have already written the first three sentences of the full article: let @xmath7 denote the family of functions @xmath8 of the form @xmath9which are analytic in the open unit disk @xmath10 and satisfy the usual normalization condition @xmath11 let @xmath12 denote the subclass of @xmath7 which are univalent in @xmath13 .
also let @xmath14and @xmath15 denote the subclasses of @xmath7 consisting of functions which are starlike and convex in @xmath13,respectively .
these classes can characterize as follows:@xmath16@xmath17 some special functions like bessel functions play an important role in applied mathematics and physics . we know that the bessel functions of the first kind @xmath18 is defined by(see @xcite and @xcite)@xmath19where @xmath20 stands for euler gamma function and it is a particular solution of the second - order linear homogeneous differential equation(see , for details , @xcite and @xcite):@xmath21 y(z)=0 \label{1.5}\]]where @xmath22 now , we consider the function @xmath23 defined by(see @xcite ) @xmath24on the other hand we know that there is following relation in between pochhammer symbol ( or appell ) and euler s gamma function:@xmath25if we use the relation ( 1.7 ) we can obtain the following series representation for the functions @xmath26 given by ( 1.6):@xmath27where @xmath28 in this study.
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, we will investigate the ratio of a function of the form ( 1.8 ) to its sequence of partial sums @xmath29 when the coefficients of @xmath30 satisfy some conditions .
we will obtain lower bounds for @xmath31 @xmath32 @xmath33 and @xmath34 for interesting developments on the partial sums of some special functions and the some classes of analytic functions , the readers can browse to the works of orhan and yagmur @xcite , alar and deniz @xcite , brickman et al .
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Suppose that you have an abstract for a scientific paper: we study supersymmetric wilson loops in the @xmath0 supersymmetric @xmath1 chern - simons - matter ( csm ) theory , the abj theory , at finite @xmath2 , @xmath3 and @xmath4 .
this generalizes our previous study on the abj partition function . first computing the wilson loops in the @xmath5 lens space matrix model exactly
, we perform an analytic continuation , @xmath3 to @xmath6 , to obtain the wilson loops in the abj theory that is given in terms of a formal series and only valid in perturbation theory . via a sommerfeld - watson type transform
, we provide a nonperturbative completion that renders the formal series well - defined at all couplings .
this is given by @xmath7-dimensional integrals that generalize the `` mirror description '' of the partition function of the abjm theory .
using our results , we find the maps between the wilson loops in the original and seiberg dual theories and prove the duality . in our approach
we can explicitly see how the perturbative and nonperturbative contributions to the wilson loops are exchanged under the duality .
the duality maps are further supported by a heuristic yet very useful argument based on the brane configuration as well as an alternative derivation based on that of kapustin and willett .
@xmath8_school of physics and center for theoretical physics _
+ _ university of the witwatersrand _ + _ wits 2050 , johannesburg ,
south africa
_ + @xmath9_department of physics _ + _ nagoya university , nagoya 464 - 8602 , japan _ + @xmath10_yukawa institute for theoretical physics _ + _ kyoto university , kyoto 606 - 8502 , japan _
+ @xmath11_hakubi center , kyoto university , kyoto 606 - 8501 , japan _ .
And you have already written the first three sentences of the full article: duality is one of the most fascinating phenomena in quantum field theory .
it provides an alternative , often non - perturbative , understanding of the theory that is not accessible in the original description .
seiberg duality @xcite , under which weakly coupled gauge theory is mapped into strongly coupled one with different rank , and vice versa , is a prominent example ..
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although the mapping of local operators under seiberg duality is known to be rather simple @xcite , the transformation properties of non - local operators , such as wilson loops , are more non - trivial and less studied . by its strong - weak nature
, any checks of seiberg duality must involve a non - perturbative approach .
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Suppose that you have an abstract for a scientific paper: the transport in double - barrier heterostructures of electrons interacting with longitudinal optical phonons in the presence of parallel electric and magnetic fields is analyzed theoretically with the aid of a 3-dimensional quantum transport simulator .
inter landau state transitions induced by lo - phonon scattering - assisted resonant - tunneling is shown to be an important process with a probability comparable to that of intra landau state scattering .
analysis of the current - voltage characteristics reveals also that the current peak is a periodic function of the inverse of the magnetic field , with a period dependent on the quasi - resonant energy level . .
And you have already written the first three sentences of the full article: the magnetotransport phenomena @xcite in multiple - barrier heterostructures in which the magnetic is applied parallel to the electric field , was first reported by mendez , esaki and wang @xcite .
the experimental data acquired in the presence of a magnetic field exhibited abnormal features such as a shift of the onset voltage @xcite , an increase of the peak - to - valley current ratio , as well as the presence of additional shoulders in the valley region of the i - v characteristics @xcite .
however , these observations have not been fully accounted for on a theoretical basis ..
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this is partly due to the fact that a 3-dimensional treatment of the electron motion is required for rigorously analyzing the impact the quantization in the transverse plane has upon the longitudinal electron motion .
indeed relatively few works analyzing heterostructure devices with a magnetic field parallel to the electric field have been reported until now @xcite .
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Suppose that you have an abstract for a scientific paper: we investigate superconductor / ferromagnet ( s / f ) hybrid structures in the dirty limit , described by the usadel equations .
more precisely , the oscillations of the critical temperature and critical current with the thickness of the ferromagnetic layers are studied .
we show that spin - flip and spin - orbit scattering lead to the decrease of the decay length and the increase of the oscillations period .
the critical current decay is more sensitive to these pair - breaking mechanisms than that of the critical temperature .
these two scattering mechanisms should be taken into account to get a better agreement between experimental results and theoretical description .
we also study the influence of the interface transparency on the properties of s / f structures . .
And you have already written the first three sentences of the full article: it has been known for quite a long time that superconductivity ( s ) and ferromagnetism ( f ) are two antagonistic orderings and that they can hardly coexist in a same compound .
although they tend to avoid each other , their mutual interaction may be studied when they are spatially separated , which is realized in superconductor / ferromagnet ( s / f ) hybrid structures ( as a review , see @xcite ) . indeed , in such systems , superconductivity and ferromagnetism
can influence each other through the so called proximity effect. the main peculiarity of the proximity effect in s / f structures is the damping oscillatory behavior of the superconducting correlations in the f layers ( while they monotonically decay in normal layers of superconductor / normal metal structures ) . in the dirty limit and for large exchange field , the characteristic lengths of the decay and oscillations are the same ..
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they are given by @xmath0 , where @xmath1 is the diffusion coefficient in the ferromagnet and @xmath2 is the exchange field acting on the electrons spins .
this unusual proximity effect leads to several striking phenomena , such as the non - monotonic dependence of the critical temperature and current of s / f multilayers on the f layers thickness and the realization of the so - called @xmath3 junction in s / f / s trilayers @xcite . although the existing theory provides rather good qualitative description of the observed _ _ _ _ effects , there is still no complete quantitative agreement with experiments .
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Suppose that you have an abstract for a scientific paper: the effects of the residual proton - neutron interactions on bandcrossing features are studied by means of shell model calculations for nucleons in a high - j intruder orbital .
the presence of an odd - nucleon shifts the frequency of the alignment of two nucleons of the other kind along the axis of rotation .
it is shown that the anomalous delayed crossing observed in nuclei with aligning neutrons and protons occupying the same intruder subshell can be partly attributed to these residual interactions . .
And you have already written the first three sentences of the full article: the cranked shell model ( csm ) approach @xcite accounts well for the overall systematics of bandcrossing phenomena in rapidly rotating medium and heavy mass nuclei . in this model
the protons and neutrons move independently in a fixed rotating potential . as a consequence of this assumption ,
the alignment of a pair of neutrons with the rotational axis occurs at the same rotational frequency for different proton configurations ..
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however , recently substantial deviations from this simple picture have been reported using the csm approach in the high - spin study of nuclei near @xmath0 @xcite and for nuclei with aligning neutrons and protons occupying the same intruder subshell @xcite . these deviations , concerning the crossing between the g - band and the s - band in the even - neutron systems referred to as the ( ab)-crossing , include : * the crossing in the odd - proton nuclei
is considerably delayed as compared to the neighboring even - even nuclei , * in the case of @xmath0 even - even nuclei , the ( ab)-crossing is substantially delayed as compared to the neighboring @xmath1 .
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Suppose that you have an abstract for a scientific paper: the formulation of qcd which contains no divergences and no renormalization procedure is presented .
it contains both perturbative and non - perturbative phenomena .
it is shown that , due to its asymptotically free nature , the theory is not defined uniquely .
the chiral symmetry breaking and the nature of the octet of pseudo - scalar particles as quasi - goldstone states are analysed in the theory with massless and massive quarks .
the @xmath0 problem is discussed .
-1 cm .0 cm .0 cm 9 in 6.5 in = 2ex `
bonn tk 97 - 08 * qcd at large and short distances + ( annotated version ) * vladimir gribov _ landau institute for theoretical physics , moscow + and + research institute for particle and nuclear physics , budapest + and + institut fr theoretische kernphysik der universitt bonn _
july 28 , 1997 .
And you have already written the first three sentences of the full article: in this paper i show how to formulate an asymptotically free theory in such a way that it includes perturbative and non - perturbative phenomena simultaneously .
the idea is the following .
contrary to an infrared free theory , in an asymptotically free theory the divergences prevent us from writing even perturbation expansions in a unique , well - defined way ..
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we can , however , make use of the fact that divergences in the theory enter only the green s functions and the vertices . on the other hand , knowing the green s functions and the vertices we can express all the other amplitudes through them perturbatively in a unique way .
thus , we have to formulate equations for green s functions and vertices in a form which does not contain any divergences .
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Suppose that you have an abstract for a scientific paper: rotational constraint representing a local external bias generally has non - trivial effect on the critical behavior of lattice statistical models in equilibrium critical phenomena . in order to study the effect of rotational bias in a out of equilibrium situation like self - organized criticality
, a new two state `` quasi - deterministic '' rotational sandpile model is developed here imposing rotational constraint on the flow of sand grains .
an extended set of new critical exponents are found to characterize the avalanche properties at the non - equilibrium steady state of the model .
the probability distribution functions are found to obey usual finite size scaling supported by negative time autocorrelation between the toppling waves .
the model exhibits characteristics of both deterministic and stochastic sandpile models . .
And you have already written the first three sentences of the full article: the phenomenon that a class of externally slow driven systems evolves naturally into a state of no single characteristic size or time without fine tuning of any parameter is known as self - organized criticality ( soc)@xcite . in soc , the system evolves into a non - equilibrium steady state characterized by long range spatio - temporal correlations and power law scaling behavior as observed in equilibrium critical phenomena@xcite .
the phenomenon is observed in many natural physical and chemical processes@xcite .
sandpile , a prototypical model , was introduced by bak , tang and wiesenfeld ( btw)@xcite for studying soc ..
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the system here is driven by adding sand grains , one at a time , randomly to the sites of a regular lattice . in btw
, the model evolves following certain deterministic rules for distributing grains of a sand column among all the nearest neighbors equally if the height of a column attains a predefined critical height .
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Suppose that you have an abstract for a scientific paper: we present a high statistic systematic study of the overlap correlation function well below the critical temperature in the three dimensional gaussian spin glass .
the off - equilibrium correlation function has been studied confirming the power law behavior for the dynamical correlation length . in particular
we have computed the dynamical critical exponent @xmath0 in a wide range of temperatures , @xmath1 , obtaining a dependence @xmath2 in a very good agreement with recent experiments .
moreover , we report a study of the violation of the fluctuation - dissipation theorem for very low temperatures @xmath3 and @xmath4 .
all our numerical results avoid a droplet model interpretation even when @xmath5 is as low as @xmath4 . .
And you have already written the first three sentences of the full article: the nature of the low temperature phase of finite dimensional spin glasses is still a subject of controversy @xcite .
recently bray , moore , bokil and drossel @xcite have questioned many of the numerical results obtained with monte carlo methods in the three dimensional edwards - anderson ( ea ) model @xcite . inspired by the study of the migdal - kadanoff approximation ( mka ) of the ea model , they argued that the numerical results , that were obtained at temperatures @xmath6 , could be strongly affected by finite size effects and that one should go to sizes larger than the crossover length @xmath7 in order to see the right ( droplet ) behavior .
they found ( in the framework of the mka ) that the crossover length is @xmath8 for @xmath9 and that it decreases for lower temperatures : @xmath10 when @xmath11 @xcite ( see also the comment @xcite ) ..
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this is maybe the main motivation that pushed us to study the ea model in the very low temperature region : verify whether the behavior already found at @xmath12 persists at @xmath13 .
in fact at these temperatures we can simulate ( using off - equilibrium techniques ) a system of size larger than @xmath7 ( in this paper , we will present data for sizes @xmath14 and @xmath15 ) .
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Suppose that you have an abstract for a scientific paper: we find a parametric resonance in the ghz range of the dna dynamics , generated by pumping hypersound .
there are localized phonon modes caused by the random structure of elastic modulii due to the sequence of base pairs . .
And you have already written the first three sentences of the full article: molecule of the dna has unusual elastic properties owing to its helicoidal symmetry and the sequence of base - pairs . from the physical view - point , i.e. neglecting its genetic information , the latter looks random .
the vibrational dynamics of the dna has an important bearing upon biological phenomenae in cell , @xcite , see also@xcite .
a specific feature of the dynamics is localized motions in the duplex which spread only over several base - pairs ..
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their existence has been confirmed by the experimental research using the raman scattering , @xcite,@xcite , @xcite , @xcite , the far - infrared absorption , @xcite,@xcite , and the brillouin scattering @xcite . in paper
@xcite the vibrational modes have been studied using the submillimeter - wave absorption spectroscopy in the range of @xmath0 thz .
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Suppose that you have an abstract for a scientific paper: we report on the most recent experimental progress on @xmath0 charmoniumlike meson states and their possible counterparts in the @xmath1 and @xmath2 systems . .
And you have already written the first three sentences of the full article: the results presented here are based on a data sample collected with the belle detector @xcite at the kekb asymmetric - energy @xmath3 collider @xcite .
the experiment is located at the high energy accelerator research organization ( kek ) in tsukuba , japan .
electrons and positrons are being collided at the center - of - mass ( cm ) energy of about 10.58 gev , corresponding to the mass of the @xmath4 resonance ..
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the main objective of the belle experiment is a study of the @xmath5 violation in the @xmath6 meson system produced from @xmath4 , however a large data sample collected with the belle detector and its excellent performance also make possible to perfrom searches for new hadronic states as well as studies of their properties .
there are several possible mechanisms of the particle production at @xmath6 factories : production in the @xmath6 meson decays , fragmentation of quarks in @xmath3 annihilation or two - photon collisions .
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Suppose that you have an abstract for a scientific paper: we propose a scenario in which roper octet can mix with a putative antidecuplet of exotic baryons and predict the properties of its strange members .
we show that @xmath0 and @xmath1 .
we also estimate total widths : @xmath2 and @xmath3 and branching ratios for different decay modes . .
And you have already written the first three sentences of the full article: at the end of 2002 japanese collaboration leps at spring-8 @xcite and the bubble chamber experiment diana at itep , moscow @xcite , announced evidence of a strange baryon , called @xmath4 , whose quantum numbers can not be constructed from 3 quarks .
this truly exotic state : ( @xmath5 ) has been anticipated already by the founders of the quark model , however it was believed to be rather heavy ( 1800 1900 mev ) and wide .
the excitement created by the findings of leps and diana was due to the low mass of the putative @xmath4 , of the order of 1530 mev , and a very small width ..
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such properties , however , are natural in chiral models where the antistrange quark is excited in form of a chiral field rather than as a constituent quark .
early predictions of the @xmath4 mass in different versions of the chiral models were very close to the experimental numbers of leps and diana @xcite , and moreover the width , as estimated by diakonov , petrov and polyakov in 1997 , was very small @xcite .
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Suppose that you have an abstract for a scientific paper: we re - examine the evidence for the existence of ultra - massive ( @xmath0 ) white dwarfs based on gravitational redshift of white dwarfs in common proper motion binaries or in clusters , on parallax measurements , on orbital solutions , and , finally , on the analysis of hydrogen line profiles .
we conclude that the best evidence is largely based on the analysis of balmer line profiles although the companion to the a8v star hr 8210 is a compelling case made initially using the large binary mass function and confirmed by an analysis of the lyman line spectrum .
the confirmation and identification of high - mass white dwarfs , more particularly non - da white dwarfs , using parallax measurements may prove critical in establishing the population fraction of these objects and in constraining the high - end of empirical initial - mass to final - mass relations .
the existence of a substantial population of ultra - massive white dwarfs supports the concept of a steeper initial - mass to final - mass relations linking @xmath1 progenitors with @xmath2 white dwarfs .
[ firstpage ] stars : evolution stars : fundamental parameters white dwarfs .
And you have already written the first three sentences of the full article: ultra - massive white dwarfs , generally defined as having masses exceeding @xmath3 , remained relatively rare until deep spectroscopic surveys uncovered these intrinsically faint objects . the hot hydrogen - rich ( da ) white dwarf gd 50 @xcite , the carbon - rich white dwarf g35 - 26 @xcite , and two da white dwarfs ( pg 1658 + 441 and pg 0136 + 251 ) from the palomar - green survey @xcite were rare examples of this phenomenon .
interestingly , spectroscopic follow - up of extreme ultraviolet ( euv ) surveys of the local ( @xmath4 pc ) , hot white dwarf population managed to identify many new ultra - massive white dwarfs on the basis of a _ large , spectroscopically determined surface gravity _ ( @xmath5 ) .
based on the _ extreme ultraviolet explorer _.
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( _ euve _ ) and rosat _ wide field camera _ ( _ wfc _ ) surveys , @xcite , @xcite , @xcite , and @xcite added a dozen new objects to the population .
more recently , a re - analysis of the palomar - green ( pg ) sample of da white dwarfs @xcite and a study of the white dwarf mass distribution in the sloan digital sky survey ( sdss ; * ? ? ?
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Suppose that you have an abstract for a scientific paper: we review several different approaches for computing casimir forces and related fluctuation - induced interactions between bodies of arbitrary shapes and materials . the relationships between this problem and well known computational techniques from classical electromagnetism are emphasized .
we also review the basic principles of standard computational methods , categorizing them according to three criteria choice of problem , basis , and solution technique that can be used to classify proposals for the casimir problem as well . in this way
, mature classical methods can be exploited to model casimir physics , with a few important modifications . .
And you have already written the first three sentences of the full article: thanks to the ubiquity of powerful , general - purpose computers , large - scale numerical calculations have become an important part of every field of science and engineering , enabling quantitative predictions , analysis , and design of ever more complex systems .
there are a wide variety of different approaches to such calculations , and there is no single `` best '' method for all circumstances not only are some methods better suited to particular situations than to others , but there are also often severe trade - offs between generality / simplicity and theoretical efficiency . even in relatively mature areas like
computational classical electromagnetism ( em ) , a variety of techniques spanning a broad range of sophistication and generality remain in widespread use ( and new variations are continually developed ) @xcite ..
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semi - analytical approaches also remain important , especially perturbative techniques to decompose problems containing widely differing length scales ( the most challenging situation for brute - force numerics ) .
nevertheless , many commonalities and guiding principles can be identified that seem to apply to a range of numerical techniques .
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Suppose that you have an abstract for a scientific paper: we consider dilute gases of dipolar bosons or fermions in the high - temperature limit in a spherically symmetric harmonic trapping potential . we examine the system using a virial expansion up to second order in the fugacity .
using the born approximation and assuming purely dipolar interactions , we find that the second - order virial coefficient for both bosons and fermions depends quadratically on the dipole length and is negative at high temperature , indicating that to lowest order in the dipole - dipole interactions the dipolar single - component quantum gases are repulsive . if the @xmath0-wave scattering length for the bosonic system is tunable and its absolute value is made small , then the @xmath0-wave interactions dominate and the dipolar gas behaves like a weakly - interacting bose gas with isotropic @xmath0-wave interactions .
if the generalized scattering lengths for the fermionic system are tunable , then the dipole length can enter linearly in the virial equation of state , enhancing the dipole - dipole effects in the thermodynamic observables . .
And you have already written the first three sentences of the full article: there has been much interest in the past few years in ultracold systems of dipoles @xcite .
anisotropic long - range interactions can arise due to the interactions between the magnetic moments of atoms or due to the interactions between heteronuclear diatomic molecules ( in this case , each molecule is treated as an electric dipole ) .
experimentally , dipole - dipole interactions play a prominent role in the dynamics of ultracold atomic clouds consisting of cr @xcite , dy @xcite , and er @xcite . in these systems , the effects of the dipole - dipole interactions have been observed in the degenerate regime via expansion cloud imaging @xcite ..
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additionally , polar molecules such as krb @xcite , rbcs @xcite and lics @xcite have been created and the effects of the anisotropic interactions have been observed in krb clouds with phase space densities just above degeneracy @xcite . it remains an open question whether the effects from the anisotropic and long - range dipole - dipole interactions can be observed in thermodynamic observables at high temperature , i.e. , at temperatures above the degeneracy temperature .
for isotropic short - range interactions , the high - temperature behavior of two - component fermi gases is well described by the virial equation of state @xcite . at unitarity ,
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Suppose that you have an abstract for a scientific paper: we analyze the evolution equation describing all multiple hard pomeron exchanges in a hadronic or nuclear structure functions that was proposed earlier in @xcite .
we construct a perturbation series providing us with an exact solution to the equation outside of the saturation region .
the series demonstrates how at moderately high energies the corrections to the single bfkl pomeron exchange contribution which are due to the multiple pomeron exchanges start unitarizing total deep inelastic scattering cross section .
we show that as energy increases the scattering cross section of the quark
antiquark pair of a fixed transverse separation on a hadron or nucleus given by the solution of our equation inside of the saturation region unitarizes and becomes independent of energy .
the corresponding @xmath0 structure function also unitarizes and becomes linearly proportional to @xmath1 .
we also discuss possible applications of the developed technique to diffraction .
16.5 cm -1 cm 22.4 cm cern - th/99 - 166 + nuc - mn-99/8-t + tpi - minn-99/26 * unitarization of the bfkl pomeron on a nucleus * + yuri v. kovchegov + + _ theory division , cern + ch-1211 , geneva , switzerland _ + + and + + _ school of physics and astronomy , university of minnesota , + minneapolis , mn 55455 , usa _ + + + .
And you have already written the first three sentences of the full article: the balitsky , fadin , kuraev and lipatov ( bfkl ) @xcite equation resums all leading logarithms of bjorken @xmath2 for hadronic cross sections and structure functions . the solution of the bfkl equation grows like a power of center of mass energy @xmath3 , therefore violating the unitarity bound at very high energies @xcite .
this is one of the major problems of small @xmath2 physics , since the froissart bound @xcite states that the total cross section should not raise faster than @xmath4 at asymptotically high energies .
there is a general belief that the unitarity problem could be cured by resumming all multiple bfkl pomeron exchanges in the total cross section , or , equivalently , in the structure function . as was argued by mueller in @xcite multiple pomeron exchanges.
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become important at the values of rapidity of the order of @xmath5 with @xmath6 the strong coupling constant , which is assumed to be small , and @xmath7 .
this result could be obtained if one notes that one pomeron contribution to the total cross section of , for instance , onium onium scattering , is parametrically of the order of @xmath8 $ ] and the contribution of the double pomeron exchange is @xmath9 $ ] . since multiple pomeron exchanges become important when the single and double pomeron exchange contributions become comparable , we recover eq .
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Suppose that you have an abstract for a scientific paper: the sn explosion in the closed binary can give the magnetospheric flare possessing the properties of grb .
the sn shock , flowing around the magnetosphere of a magnetized neutron star or a white dwarf , produces a narrow magnetic tail @xmath0 long , @xmath1 wide and a magnetic field of @xmath2 .
fast particles ( @xmath3 ) , generated in the tail by reconnection processes , radiate gamma rays of the @xmath4 - @xmath5 energies .
the duration of radiation @xmath6 corresponds to a short grb .
apart , the powerful shock can tear and accelerate part of the tail .
that is the relativistic ( @xmath7 ) , strongly magnetized jet , producing gamma radiation and also x - ray and optic afterglow .
that is a long ( @xmath8 ) grb .
the duration of the afterglow is inversely proportional to the photon energy and is several months for optic . , gamma rays bursts , supernovae , magnetic tail ( magnetosphere ) , synchrotron radiation 98.70.r , 97.60.b , 94.30.c .
And you have already written the first three sentences of the full article: identification of two tens of the long grb ( @xmath9 ) with the extragalactic objects located at cosmological distances ( @xmath10 ) raises a question about the source of energy release . for the spherical symmetry
the energy yield is turned to be as abnormally large as @xmath11 only in the band of thousands of @xmath12 .
such energy release is comparable with that of a supernova explosion ( sn ) , for which @xmath13 of the energy is escaped by neutrinos during the first several seconds . to overcome the energy catastrophe in the problem of grb a hypothesis.
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was suggested about a strong collimation of the gamma radiation in the narrow solid angle of @xmath14 .
this assumption gives a possibility to diminish the luminosity of grb , needed for the explanation of the observed gamma - ray flux , by a factor of @xmath15 which for @xmath14 gives the gain of @xmath16 .
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Suppose that you have an abstract for a scientific paper: use of non one - dimensional distributed feedback in vfel gives possibility of frequency tuning in wide range . in present work dependence of lasing process on the angle between resonant diffraction grating grooves and direction of electron beam velocity
is discussed .
volume free electron laser ( vfel ) , volume distributed feedback ( vdfb ) , diffraction grating , smith - purcell radiation , electron beam instability 41.60.c , 41.75.f , h , 42.79.d .
And you have already written the first three sentences of the full article: new advances in different areas require the development of tunable , wide - band , high - power sources of coherent electromagnetic radiation in gigahertz , terahertz and higher frequency ranges .
conventional electron vacuum devices have restricted possibility of frequency tuning ( usually it does not exceed 5 - 10% ) for the certain carrier frequency at certain e - beam energy .
volume free electron laser ( vfel)@xcite was proposed as a new type of free electron laser ..
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frequency tuning , possibility of use of wide electron beams ( several e - beams ) and reduction of threshold current density necessary for start of generation , provided by vfel , make it a basis for development of more compact , high - power and tunable radiation sources then conventional electron vacuum devices could let .
first lasing of vfel was reported at fel 2001 @xcite .
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Suppose that you have an abstract for a scientific paper: it is shown that the inflationary era in early universe is realized due to the effect of backreaction of quantized matter fields .
in fact we start by quantizing a free scalar field in the friedmann - robertson - walker space - time , and the field is fluctuating quantum mechanically around the bottom of the mass potential .
we then obtain the vacuum expectation value of the energy density of the scalar field as a functional of the scale factor @xmath0 of the universe . by plugging it into the einstein equation
, a self - consistent equation is established in which the matter fields determine the time evolution of the universe .
we solve this equation by setting few conditions and find the following solution : the universe expands la de sitter with e - folding number @xmath1 and then it turns to shrink with a decreasing hubble parameter @xmath2 which rapidly goes to zero . * a new mechanism of realizing inflationary universe + * with recourse to backreaction of quantized free fields + inflation without inflaton + * * yoshinobu habara@xmath3 , hikaru kawai@xmath4 and masao ninomiya@xmath5 @xmath5okayama institute for quantum physics , 1 - 9 - 1 kyoyama , okayama 700 - 0015 , japan @xmath6department of physics , kyoto university , kyoto 606 - 8502 , japan [email protected] , + [email protected] , + [email protected] pacs numbers : 04.62.+v , 98.80.cq , 11.25.-w , 11.25.mj , 98.80.qc keywords : inflation , string theory , cosmic microwave background .
And you have already written the first three sentences of the full article: it is believed by most astro - cosmologists as well as astro - particle physicists that the only solution to resolve the flatness and horizon problems in the universe is to think of exponential expansion called inflation @xcite right after birth of our universe . in recent years
several observational results to confirm the inflation were reported @xcite .
in particular , the most important evidence in the present days to provide data is the temperature fluctuation of the cosmic microwave background radiation ( cmb ) which shows us quantitatively that there was the era of the inflation in the early universe . using this data we can investigate the mechanism of the inflationary expansion in detail ..
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the cmb is the photon emitted in the recombination era of which the wavelength is very long so that cmb reaches us without much scattering afterwards .
therefore cmb carries to us the information of the early universe .
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Suppose that you have an abstract for a scientific paper: a type iia string compactified on a calabi
yau manifold which admits a k3 fibration is believed to be equivalent to a heterotic string in four dimensions .
we study cases where a calabi yau manifold can have more than one such fibration leading to equivalences between perturbatively inequivalent heterotic strings .
this allows an analysis of an example in six dimensions due to duff , minasian and witten and enables us to go some way to prove a conjecture by kachru and vafa .
the interplay between gauge groups which arise perturbatively and nonperturbatively is seen clearly in this example . as an extreme case
we discuss a calabi
yau manifold which admits an infinite number of k3 fibrations leading to infinite set of equivalent heterotic strings .
epsf # 1date_#1 _ # 1thefnmarkfootnotetext1991 _ mathematics subject classification .
_ # 1 # 1thefnmarkfootnotetext _ key words and phrases .
_ # 1 ps . @firstpageps .
@empty oddhead evenheadoddhead # 1 .
And you have already written the first three sentences of the full article: 40004000 = 1000 = ifundefinedreset@font@font footnotetext#1 tempcntc citex[#1]#2@fileswauxout tempcnta@tempcntb@neciteaciteforciteb:=#2citeo#1 citeotempcnta > tempcntbcitea citea , m tempcnta = tempcntbtempcnta # 1 o p # 1#1 # 1 # 1 # 1 # 1 # 1#2 # 1#2_#1f_#2 # 1#1 # 1#1 _ # 1@xmath0 # 1 _ 0
it is now generally believed that the type iia string compactified down to six dimensions on a k3 surface gives the same physics as a heterotic string compactified on a four - torus ( see , for example , @xcite ) .
it was suggested in @xcite that much the same effect could be seen in four dimensions for @xmath1 theories ..
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that is , a type ii string compactified on a threefold could be equivalent to a heterotic string compactified on an object , essentially a k3 surface times a two - torus , for a suitable manifold .
let us suppose that we have a type iia string compactified on a manifold , @xmath2 .
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Suppose that you have an abstract for a scientific paper: we have examined @xmath0 vertex to obtain the limits on anomalous @xmath1 , @xmath2 and @xmath3 couplings in a model independent way through the @xmath4 collisions via the process @xmath5 .
the sensitivities to the anomalous couplings can be obtained as @xmath6 , @xmath7 for the integrated luminosity of @xmath8 at the lhc with @xmath9 tev . .
And you have already written the first three sentences of the full article: after the discovery of higgs boson by the atlas and cms collaborations at the lhc @xcite , properties of higgs boson have been studied extensively .
higgs boson couplings to the standard model ( sm ) particles are important because these couplings may give some hints for physics beyond the sm .
tree - level neutral bosons coupling for @xmath0 vanish within the electroweak interactions . therefore , any detected signals of these tree - level couplings would indicate the existence of new physics . in a common scenario beyond the sm.
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, the corrections from higher dimensional operators can be calculated through an effective lagrangian .
being consistent with lorentz and gauge invariance , the general structure for @xmath0 vertex can be written as @xcite , @xmath10,\ ] ] where @xmath11 and @xmath12 represent momentum of photon and @xmath13 boson , respectively .
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Suppose that you have an abstract for a scientific paper: quantum field theories with an energy gap can be approximated at long - range by _ topological _ quantum field theories .
the same should be true for suitable condensed matter systems .
for those with _ short range entanglement _ ( sre ) the effective topological theory is _
invertible _ , and so amenable to study via stable homotopy theory .
this leads to concrete topological invariants of gapped sre phases which are finer than existing invariants .
computations in examples demonstrate their effectiveness .
plus4.5pt minus9pt plus4.5pt 10.5pt plus4.5pt minus6pt = 15 truept .
And you have already written the first three sentences of the full article: the long - range behavior of gapped systems in condensed matter physics is accessible via topology . for noninteracting fermionic systems
there is a classification of topological phases using ideas related to @xmath0-theory @xcite . over the past few years
the interacting case has been vigorously studied , for both fermionic systems and bosonic systems , with an emphasis on _ short - range entanglement _ ( sre ) ; a small sampling of papers is @xcite ..
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symmetry protected topological _ ( spt ) phases are captured by group cohomology @xcite , but other investigations ( e.g. @xcite ) reveal the existence of additional sre phases and raise the question of a complete classification . in this paper
we propose an invariant of bosonic and fermionic sre topological phases constructed from effective field theory .
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Suppose that you have an abstract for a scientific paper: we use the evolving surface finite element method to solve a cahn - hilliard equation on an evolving surface with prescribed velocity .
we start by deriving the equation using a conservation law and appropriate transport formulae and provide the necessary functional analytic setting .
the finite element method relies on evolving an initial triangulation by moving the nodes according to the prescribed velocity .
we go on to show a rigorous well - posedness result for the continuous equations by showing convergence , along a subsequence , of the finite element scheme .
we conclude the paper by deriving error estimates and present various numerical examples . .
And you have already written the first three sentences of the full article: in this paper , we will study a cahn - hilliard equation posed on an evolving surface with prescribed velocity .
the key methodology is to discretise the equations using the evolving surface finite element method @xcite originally proposed for a surface heat equation .
the idea is to take a triangulation of the initial surface and evolve the nodes along the velocity field ..
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this leads to a family of discrete surfaces on which we can pose a variational form of the cahn - hilliard equation .
there are two key results in this paper : first , we show well posedness of the continuous scheme and , second , we show convergence of a finite element scheme .
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Suppose that you have an abstract for a scientific paper: star formation is evolving very fast in the second half of the universe , and it is yet unclear whether this is due to evolving gas content , or evolving star formation efficiency ( sfe ) . we have carried out a survey of ultra - luminous galaxies ( ulirg ) between z=0.2 and 1 , to check the gas fraction in this domain of redshift which is still poorly known .
our survey with the iram-30 m detected 33 galaxies out of 69 , and we derive a significant evolution of both the gas fraction and sfe of ulirgs over the whole period , and in particular a turning point around z=0.35 .
the result is sensitive to the co - to- conversion factor adopted , and both gas fraction and sfe have comparable evolution , when we adopt the low starburst conversion factor of @xmath0 = 0.8 m@xmath1 ( k pc@xmath2)@xmath3 .
adopting a higher @xmath0 will increase the role of the gas fraction .
using @xmath0 = 0.8 , the sfe and the gas fraction for [email protected] - 1.0 ulirgs are found to be significantly higher , by a factor 3 , than for local ulirgs , and are comparable to high redshift ones .
we compare this evolution to the expected cosmic abundance and the cosmic star formation history . .
And you have already written the first three sentences of the full article: star formation ( sf ) was processing at a much larger rate in galaxies in the first half of the universe history , and the most striking feature in the cosmic sf rate density is the decline by a factor @xmath4 10 since z=1 ( madau 1998 , hopkins & beacom 2006 ) .
several factors could be invoked to explain such a behavior : first the gas fraction in star forming galaxies is likely to have been higher in the past , as already suggested by co surveys , tracing the molecular gas content of galaxies . locally , the gas fraction for giant spirals is about 7 - 10% ( leroy 2008 , saintonge 2011a ) , while at [email protected] it increases to 34@xmath55% and at [email protected] to 44@xmath56% ( tacconi 2010 , daddi 2010 ) .
second , the star formation efficiency might have been higher in the past , due to the dynamical trigger of galaxy interactions , whose frequency increases with redshift ( e.g. conselice 2009 , kartaltepe 2010 ) , and also the more violent instabilities in more unstable disks , with lower bulge - to - disk ratios ..
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the star formation efficiency ( sfe ) defined as the ratio of sfr to gas content , has been observed to increase with redshift ( e.g. greve 2005 ) , even for the most extreme starbursts , represented by ultra - luminous infrared galaxies ( ulirg ) .
this tendency is however supported mainly by comparing local and high - z galaxies , at z@xmath61 , and very little is known about the molecular gas content of galaxies at intermediate redshift between z=0.2 and 1 .
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Suppose that you have an abstract for a scientific paper: we investigate a semiconductor @xmath0-@xmath1 junction in contact with superconducting leads that is operated under forward bias as a light - emitting diode .
the presence of superconductivity results in a significant increase of the electroluminescence in a sharp frequency window .
we demonstrate that the tunneling of cooper pairs induces an additional luminescence peak on resonance .
there is a transfer of superconducting to photonic coherence that results in the emission of entangled photon pairs and squeezing of the fluctuations in the quadrature amplitudes of the emitted light .
we show that the squeezing angle can be electrically manipulated by changing the relative phase of the order parameters in the superconductors .
we finally derive the conditions for lasing in the system and show that the laser threshold is reduced due to superconductivity .
this reveals how the macroscopic coherence of a superconductor can be used to control the properties of light . .
And you have already written the first three sentences of the full article: superconductors exhibit quantum coherence of electronic degrees of freedom on a macroscopic scale . for @xmath2-wave pairing they are characterized by a complex pairing amplitude @xmath3 with a well - defined phase
@xmath4 @xcite .
this is a consequence of the off - diagonal long - range order present in the two - particle density matrix @xcite ..
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the electrons condense into cooper pairs and form entangled two - electron singlet states .
the prospect of harvesting these useful coherence and entanglement properties for the manipulation of quantum states as required for example in quantum information processing and communication @xcite is a motivation to integrate superconducting elements in semiconductor solid - state nanostructures .
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Suppose that you have an abstract for a scientific paper: this paper is devoted to consideration of the hard exclusive processes @xmath0 , where @xmath1 .
experimental measurement of the cross section of the process @xmath2 at babar collaboration at large center mass energy @xmath3 gev and some low energy experimental data @xmath4 gev give us the possibility to study the cross section in the broad energy region . as the result
, we have determined the asymptotic behavior of the cross section of @xmath2 in the limit @xmath5 , which is in agreement with perturbative qcd prediction .
assuming that the same asymptotic behavior is valid for the other processes under consideration and using low energy experimental data we have predicted the cross sections of these processes at energies @xmath6 gev . in addition , we have calculated the cross sections of these processes at the same energies within perturbative qcd .
our results are in agreement with available experimental data . .
And you have already written the first three sentences of the full article: exclusive hadron production in high energy electron - positron annihilation is a very interesting task for theoretical and experimental investigations .
the presence of high energy scale @xmath7 that is much greater than typical hadronic scale allows one to separate the amplitude of such processes into hard part ( creation of quarks at very small distances ) and soft part ( subsequent hadronization of these quarks into experimentally observed mesons at larger distances ) .
the first part of the amplitude can be calculated within perturbative qcd ..
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the second part of the amplitude is described by distribution amplitudes ( da ) , which contain nonperturbative properties of final hadrons .
the description of hard exclusive hadron production within this pattern gives some very interesting predictions of the properties of hard exclusive processes @xcite .
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Suppose that you have an abstract for a scientific paper: we study distributed network flows as solvers in continuous time for the linear algebraic equation @xmath0 .
each node @xmath1 has access to a row @xmath2 of the matrix @xmath3 and the corresponding entry @xmath4 in the vector @xmath5 .
the first consensus + projection " flow under investigation consists of two terms , one from standard consensus dynamics and the other contributing to projection onto each affine subspace specified by the @xmath6 and @xmath4 .
the second projection consensus " flow on the other hand simply replaces the relative state feedback in consensus dynamics with projected relative state feedback . without dwell - time assumption on switching graphs , we prove that all node states converge to a common solution of the linear algebraic equation , if there is any .
the convergence is global for the consensus + projection " flow while local for the projection consensus " flow in the sense that the initial values must lie on the affine subspaces .
if the linear equation has no exact solutions , we show that the node states can converge to a ball around the least squares solution whose radius can be made arbitrarily small through selecting a sufficiently large gain for the consensus + projection " flow for a fixed bidirectional graph .
semi - global convergence to approximate least squares solutions is also demonstrated for switching balanced directed graphs under suitable conditions .
it is also shown that the projection consensus " flow drives the average of the node states to the least squares solution with a complete graph .
numerical examples are provided as illustrations of the established results . .
And you have already written the first three sentences of the full article: in the past decade , distributed consensus algorithms have attracted a significant amount of research attention @xcite , due to their wide applications in distributed control and estimation @xcite , distributed signal processing @xcite , and distributed optimization methods @xcite .
the basic idea is that a network of interconnected nodes with different initial values can reach a common value , namely an agreement or a consensus , via local information exchange as long as the communication graph is well connected .
the consensus value is informative in the sense that it can depend on all nodes initial states even if the value is not the exact average @xcite ; the consensus processes are robust against random or deterministic switching of network interactions as well as against noises @xcite . as a generalized notion ,.
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constrained consensus seeks to reach state agreement in the intersection of a number of convex sets , where each set serves as the supporting state space for a particular node @xcite .
it was shown that with doubly stochastic arc weights , a projected consensus algorithm , where each node iteratively projects a weighted average of its neighbor s values onto its supporting set , can guarantee convergence to constrained consensus when the intersection set is bounded and contains an interior point @xcite .
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Suppose that you have an abstract for a scientific paper: we study a random walk on a complex of finitely many half - lines joined at a common origin ; jumps are heavy - tailed and of two types , either one - sided ( towards the origin ) or two - sided ( symmetric ) .
transmission between half - lines via the origin is governed by an irreducible markov transition matrix , with associated stationary distribution @xmath0 .
if @xmath1 is @xmath2 for one - sided half - lines @xmath3 and @xmath4 for two - sided half - lines , and @xmath5 is the tail exponent of the jumps on half - line @xmath3 , we show that the recurrence classification for the case where all @xmath6 is determined by the sign of @xmath7 . in the case of two half - lines ,
the model fits naturally on @xmath8 and is a version of the _ oscillating random walk _ of kemperman . in that case , the cotangent criterion for recurrence becomes linear in @xmath9 and @xmath10 ; our general setting exhibits the essential non - linearity in the cotangent criterion .
for the general model , we also show existence and non - existence of polynomial moments of return times .
our moments results are sharp ( and new ) for several cases of the oscillating random walk ; they are apparently even new for the case of a homogeneous random walk on @xmath8 with symmetric increments of tail exponent @xmath11 . _
key words : _ random walk , heavy tails , recurrence , transience , passage time moments , lyapunov functions , oscillating random walk , cotangent criterion .
_ ams subject classification : _
60j05 ( primary ) ; 60j10 , 60g50 ( secondary ) .
And you have already written the first three sentences of the full article: we study markov processes on a complex of half - lines @xmath12 , where @xmath13 is finite , and all half - lines are connected at a common origin . on a given half - line
, a particle performs a random walk with a heavy - tailed increment distribution , until it would exit the half - line , when it switches ( in general , at random ) to another half - line to complete its jump . to motivate the development of the general model ,
we first discuss informally some examples ; we give formal statements later ..
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the _ one - sided oscillating random walk
_ takes place on two half - lines , which we may map onto @xmath8 . from the positive half - line ,
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Suppose that you have an abstract for a scientific paper: microlensing is a powerful tool for studying stellar atmospheres because as the source crosses regions of formally infinite magnification ( caustics ) the surface of the star is resolved , thereby allowing one to measure the radial intensity profile , both photometrically and spectroscopically .
however , caustic crossing events are relatively rare , and monitoring them requires intensive application of telescope resources .
it is therefore essential that the observational parameters needed to accurately measure the intensity profile are quantified .
we calculate the expected errors in the recovered radial intensity profile as a function of the unlensed flux , source radius , spatial resolution the recovered intensity profile , and caustic crossing time for the two principle types of caustics : point - mass and binary lenses .
we demonstrate that for both cases there exist simple scaling relations between these parameters and the resultant errors .
we find that the error as a function of the spatial resolution of the recovered profile , parameterized by the number of radial bins , increases as @xmath0 , considerably faster than the naive @xmath1 expectation .
finally , we discuss the relative advantages of binary caustic - crossing events and point - lens events .
binary events are more common , easier to plan for , and provide more homogeneous information about the stellar atmosphere .
however , a sub - class of point - mass events with low impact parameters can provide dramatically more information provided that they can be recognized in time to initiate observations .
# 1#2#1 10^#2 = + 0.2 in = 6.0 in = 8.0 in = 0.10 in = 0.5 in = 0.5 in # 1 = 0.4 in = 1 # 1 # 1 ccc 1 & 1 & 1 + 1 & 1 & 1 + 4 & 3 & 8 submitted to _ the astrophysical journal _ : feb 16 , 1998 preprint : osu - ta-2/98 .
And you have already written the first three sentences of the full article: originally proposed by paczyski ( 1986 ) as a method to detect the presence of massive compact objects in the halo of our galaxy , microlensing has increasingly been recognized as a tool for studying a broad range of astrophysical phenomena .
various applications include detection and characterization of binary and planetary systems ( mao & paczyski 1991 ; gould & loeb 1992 ) , reconstruction of the stellar mass function down to masses below the hydrogen burning limit ( paczyski 1991 ; griest et al .
1991 ; gould 1996 ) , measurement of the rotation speed of giants ( gould 1997 ) , measuring the transverse velocity of galaxies ( gould 1995a ) , and probing the central engines of quasars ( gould & gaudi 1997 ) ..
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recently , valls - gabaud ( 1994 , 1997 ) and sasselov ( 1996 ) have proposed using microlensing to study stellar atmospheres .
here we analyze this application in detail
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Suppose that you have an abstract for a scientific paper: electronic excitation energy transfer along a molecular wire depends on the relative orientation of the electronic transition dipole moments of neighboring chromophores . in porphycenes
this orientation is changed upon double proton transfer in the electronic ground state .
we explore the possibility to trigger such a double proton transfer reaction by means of an infrared pump - dump laser control scheme . to this end a quantum chemical characterization of an asymmetrically substituted porphycene is performed using density functional theory .
ground state geometries , the topology of the potential energy surface for double proton transfer , and transition energies are compared with the parent compound porphycene and a symmetric derivative . employing a simple two - dimensional model for the double proton transfer , which incorporates sequential and concerted motions , quantum dynamics simulations of the laser driven dynamics
are performed which demonstrate tautomerization control .
based on the orientation of the transition dipole moments this tautomerization may lead to an estimated change in the frster transfer coupling of about 60% . .
And you have already written the first three sentences of the full article: molecular photonic wires are of considerable interest as biomimetic models for photosynthetic light harvesting systems and as molecular devices @xcite .
lindsey et .
al . have been the first to demonstrate directed energy transfer through a porphyrin - based wire after selective excitation of a boron - dipyrrin donor @xcite ..
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subsequently , they described a number of different systems on the basis of multiporphyrin arrays @xcite including , for instance , shape persistent cyclic architectures @xcite or optoelectronic gates @xcite ( for a review , see also ref .
the energy transfer in these structures is dominated by a through - bond mechanism with some dependence on the nature of the bridge linking the chromophores @xcite .
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Suppose that you have an abstract for a scientific paper: dna bending is biologically important for genome regulation and is relevant to a range of nanotechnological systems .
recent results suggest that sharp bending is much easier than implied by the widely - used worm - like chain model ; many of these studies , however , remain controversial .
we use a coarse - grained model , previously fitted to dna s basic thermodynamic and mechanical properties , to explore strongly bent systems . we find that as the end - to - end distance is decreased sufficiently short duplexes undergo a transition to a state in which the bending strain is localized at a flexible kink that involves disruption of base - pairing and stacking . this kinked state ,
which is not well - described by the worm - like chain model , allows the duplex to more easily be sharply bent .
it is not completely flexible , however , due to constraints arising from the connectivity of both dna backbones .
we also perform a detailed comparison to recent experiments on a `` molecular vice '' that probes highly bent dna .
close agreement between simulations and experiments strengthens the hypothesis that localised bending via kinking occurs in the molecular vice and causes enhanced flexibility of duplex dna .
our calculations therefore suggests that the cost of kinking implied by this experiment is consistent with the known thermodynamic and mechanical properties of dna . .
And you have already written the first three sentences of the full article: strong bending of dna plays a critical biological role in genome maintenance and regulation , most famously evident in dna - protein complexes such as those formed in conjunction with the lac repressor @xcite , the tata binding protein @xcite and the nucleosome @xcite .
experiments have confirmed that these large bending fluctuations are not an artefact of dna - protein co - crystallization , and are observed in a variety of sensitive solution - phase assays @xcite . in the regime
where dna is not strongly bent , worm - like chain ( wlc ) models @xcite that treat dna as a semi - flexible rod are sufficient to describe its configurational behaviour @xcite ..
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it has been claimed , however , that strongly bent configurations can be reached much more easily than would be predicted by the wlc as parameterized to small fluctuations . in particular , deviations from wlc behaviour have been reported in experiments on cyclization @xcite , multimerization @xcite , in dna minicircles @xcite , in a stressed ring system @xcite and a molecular vice @xcite .
much of the evidence for super - wlc flexibility , has , however , been contested .
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Suppose that you have an abstract for a scientific paper: we consider and compare four hamiltonian formulations of thermostated mechanics , three of them kinetic , and the other one configurational .
though all four approaches `` work '' at equilibrium , their application to many - body nonequilibrium simulations can fail to provide a proper flow of heat .
all the hamiltonian formulations considered here are applied to the same prototypical two - temperature `` @xmath0 '' model of a heat - conducting chain .
this model incorporates nearest - neighbor hookes - law interactions plus a quartic tethering potential .
physically correct results , obtained with the isokinetic gaussian and nos - hoover thermostats , are compared with two other hamiltonian results .
the latter results , based on constrained hamiltonian thermostats , fail correctly to model the flow of heat . .
And you have already written the first three sentences of the full article: computational `` thermostats '' arose as a means for controlling numerical simulations of both equilibrium and nonequilibrium stationary states . _ without _ thermostats systems driven away from equilibrium heat up . _ with _ thermostats the heat generated by irreversible processes can be steadily removed , making it possible to simulate nonequilibrium steady states@xcite . because most hamiltonian - based mechanics problems conserve energy , novel _ nonhamiltonian _
ideas are typically required when thermostats are to be included .
nevertheless , several approaches to hamiltonian thermostats have been developed ..
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here we consider various approaches pioneered by bill ashurst , carl dettmann , denis evans , wm .
g. hoover , tom leete , gary morriss , shuichi nos , and les woodcock over a span of about 25 years@xcite . the simplest thermostat type maintains a ( nearly ) constant kinetic energy by `` rescaling '' the velocities at the end of each computational timestep . for a more elegant , but equivalent , _ continuous _ approach to rescaling , see the `` gaussian isokinetic '' method described in section iib and illustrated in section vii . for @xmath1
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Suppose that you have an abstract for a scientific paper: the global phase diagram of the spinless falicov - kimball model in @xmath0 spatial dimensions is obtained by renormalization - group theory .
this global phase diagram exhibits five distinct phases .
four of these phases are charge - ordered ( co ) phases , in which the system forms two sublattices with different electron densities .
the co phases occur at and near half filling of the conduction electrons for the entire range of localized electron densities .
the phase boundaries are second order , except for the intermediate and large interaction regimes , where a first - order phase boundary occurs in the central region of the phase diagram , resulting in phase coexistence at and near half filling of both localized and conduction electrons .
these two - phase or three - phase coexistence regions are between different charge - ordered phases , between charge - ordered and disordered phases , and between dense and dilute disordered phases .
the second - order phase boundaries terminate on the first - order phase transitions via critical endpoints and double critical endpoints .
the first - order phase boundary is delimited by critical points .
the cross - sections of the global phase diagram with respect to the chemical potentials and densities of the localized and conduction electrons , at all representative interactions strengths , hopping strengths , and temperatures , are calculated and exhibit ten distinct topologies .
pacs numbers : 71.10.hf , 05.30.fk , 64.60.de , 71.10.fd .
And you have already written the first three sentences of the full article: the falicov - kimball model ( fkm ) was first proposed by l. m. falicov and kimball @xcite to analyze the thermodynamics of semiconductor - metal transitions in smb@xmath1 and transition - metal oxides @xcite .
the model incorporates two types of electrons : one type can undergo hopping between sites and the other type can not hop , thereby being localized at the sites .
thus , in its introduction , fkm described the coulomb interaction between mobile @xmath2 band electrons and localized @xmath3 band electrons ..
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there have been a multitude of subsequent physical interpretations based on this interaction , including that of localized ions attractively interacting with mobile electrons , which yields crystalline formation @xcite .
another physical interpretation of the model is as a binary alloy , in which the localized degree of freedom reflects a or b atom occupation @xcite . in this paper
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Suppose that you have an abstract for a scientific paper: an experimental search for an electric - dipole moment ( edm ) of the neutron has been carried out at the institut laue - langevin ( ill ) , grenoble .
spurious signals from magnetic - field fluctuations were reduced to insignificance by the use of a cohabiting atomic - mercury magnetometer .
systematic uncertainties , including geometric - phase - induced false edms , have been carefully studied .
two independent approaches to the analysis have been adopted .
the overall results may be interpreted as an upper limit on the absolute value of the neutron edm of ( 90% cl ) . .
And you have already written the first three sentences of the full article: measurements of particle electric - dipole moments ( edms ) @xcite are of significant interest because they provide some of the tightest constraints on extensions to the standard model , such as supersymmetry , that attempt to explain the mechanisms underlying cp violation @xcite . this neutron - edm experiment , and the performance of its cohabiting mercury magnetometer ,
have been discussed in earlier publications @xcite .
the final result presented in this letter incorporates a comprehensive analysis of systematic errors , some of which were undiscovered at the time of the earlier measurements ..
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the measurement was made with ultracold neutrons ( ucns ) stored in a trap permeated by uniform @xmath0- and @xmath1-fields .
this adds terms @xmath2 and @xmath3 to the hamiltonian determining the states of the neutron .
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Suppose that you have an abstract for a scientific paper: large - scale plasma flows in the sun s convection zone likely play a major role in solar dynamics on decadal timescales .
in particular , quantifying meridional motions is a critical ingredient for understanding the solar cycle and the transport of magnetic flux .
because the signal of such features can be quite small in deep solar layers and be buried in systematics or noise , the true meridional velocity profile has remained elusive .
we perform time - distance helioseismology measurements on several years worth of gong doppler data .
a spherical harmonic decomposition technique is applied to a subset of acoustic modes to measure travel - time differences to try to obtain signatures of meridional flows throughout the solar convection zone .
center - to - limb systematics are taken into account in an intuitive , yet ad hoc manner .
travel - time differences near the surface that are consistent with a poleward flow in each hemisphere and are similar to previous work are measured .
additionally , measurements in deep layers near the base of the convection zone suggest a possible equatorward flow , as well as partial evidence of a sign change in the travel - time differences at mid - convection zone depths .
this analysis on an independent data set using different measurement techniques strengthens recent conclusions that the convection zone may have multiple `` cells '' of meridional flow .
the results may challenge the common understanding of one large conveyor belt operating in the solar convection zone .
further work with helioseismic inversions and a careful study of systematic effects are needed before firm conclusions of these large - scale flow structures can be made . .
And you have already written the first three sentences of the full article: meridional circulation plays a critical role in models of solar dynamo , magnetic flux transport , and the solar cycle @xcite .
it is well established observationally that meridional flow is poleward in each hemisphere with an amplitude of about @xmath0 in the near - surface layers , peaking in strength at mid latitudes @xcite . since mass does not pile up at the poles , it is believed that a return equatorward flow in both hemispheres is operating somewhere in the convection zone , likely near its base .
one of the most promising and complete attempts to measure this meridional circulation was during the graduate work of p. giles @xcite . using the soho spacecraft s michelson doppler imager ( mdi ) helioseismic data.
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, giles found that the poleward meridional flows continued throughout almost all of the convection zone and that there was indirect evidence of a return equatorward flow near the tachocline of a few @xmath1 .
his methods and analysis imposed a constraint of mass conservation .
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Suppose that you have an abstract for a scientific paper: we report spectra obtained with the _ spitzer space telescope _ in the @xmath0 = 14 35 @xmath1 m range of 19 nearby main - sequence stars with infrared excesses . the six stars with strong dust emission show no recognizable spectral features , suggesting that the bulk of the emitting particles have diameters larger than 10 @xmath1 m .
if the observed dust results from collisional grinding of larger solids , we infer minimum masses of the parent body population between 0.004 m@xmath2 and 0.06 m@xmath2 .
we estimate grain production rates of @xmath310@xmath4 g s@xmath5 around @xmath0 boo and hr 1570 ; selective accretion of this matter may help explain their peculiar surface abundances .
there appear to be inner truncations in the dust clouds at 48 au , 11 au , 52 au and 54 au around hr 333 , hr 506 , hr 1082 and hr 3927 , respectively . .
And you have already written the first three sentences of the full article: the discovery with iras of a large infrared excess around vega ( aumann et al .
1984 ) initiated the detailed study of other planetary systems .
we can now use the dust emission from main sequence stars to constrain models for the origin and evolution of these environments ( lagrange , backman & artymowicz 2000 , zuckerman 2001 ) with the long - term goal of developing a more comprehensive understanding of the formation and evolution of planets and related minor bodies ..
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most previous studies of the dust around main - sequence stars have been restricted to using broad - band infrared fluxes ( e. g. habing et al .
2001 , spangler et al .
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Suppose that you have an abstract for a scientific paper: we describe the implementation of slitless radial velocity measurements of extragalactic planetary nebulae ( pns ) with the 8.2 m subaru telescope and its cassegrain imaging spectrograph , focas . as a first application
, we have extended a previous search for pns in ngc 4697 to larger angular distances from its center .
a total of 218 pns were detected , and their radial velocities were measured .
we have added 56 new pn detections to the existing sample of 535 , observed previously with the eso vlt + fors imaging spectrograph ; 36 of these new 56 pns are located at angular distances larger than 230 arcsec from the center of ngc 4697 .
we compare the new focas velocities with the earlier fors velocities , for 158 of the 162 reobserved sources , finding good agreement .
we now have kinematic information extending out to 5 effective radii from the center .
the outer line - of - sight velocity dispersion is a bit lower than estimated earlier .
this result is compatible with the existence of a dark matter halo plus some degree of radial anisotropy , but the dark matter halo is rather inconspicuous , and it is still unclear how massive it can be . a more detailed global dynamical study of the whole set of pn velocities will be required to decide if they permit to narrow down the range of possible dark matter distributions in ngc 4697 .
the new radial velocities reveal no evidence of rotation at 5 effective radii . .
And you have already written the first three sentences of the full article: planetary nebulae ( pns ) in the outskirts of elliptical galaxies offer valuable kinematic information that can be used to trace the angular momentum distribution and mass distribution in these galaxies .
the classic example is the study of pns in ngc 5128 by hui et al .
( 1995 ) , later extended by peng et al ..
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( 2004 ) to 780 pns .
a dark matter halo and significant outer rotation were detected .
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Suppose that you have an abstract for a scientific paper: parallel coordinate plots ( pcps ) are among the most useful techniques for the visualization and exploration of high - dimensional data spaces .
they are especially useful for the representation of correlations among the dimensions , which identify relationships and interdependencies between variables . however , within these high - dimensional spaces , pcps face difficulties in displaying the correlation between combinations of dimensions and generally require additional display space as the number of dimensions increases . in this paper , we present a new technique for high - dimensional data visualization in which a set of low - dimensional pcps are interactively constructed by sampling user - selected subsets of the high - dimensional data space . in our technique , we first construct a graph visualization of sets of well - correlated dimensions .
users observe this graph and are able to interactively select the dimensions by sampling from its cliques , thereby dynamically specifying the most relevant lower dimensional data to be used for the construction of focused pcps .
our interactive sampling overcomes the shortcomings of the pcps by enabling the visualization of the most meaningful dimensions ( i.e. , the most relevant information ) from high - dimensional spaces .
we demonstrate the effectiveness of our technique through two case studies , where we show that the proposed interactive low - dimensional space constructions were pivotal for visualizing the high - dimensional data and discovering new patterns .
visualization , high - dimensional data , parallel coordinate plots . .
And you have already written the first three sentences of the full article: many data analysis tasks can be facilitated by high - dimensional data visualization .
for example , it is often helpful to know what sets of dimensions in the data are correlated or have a significant impact in processes such as clustering , sampling , or labeling .
another important task is the discovery of hidden relationships between labels and numeric values in the analysis of labeled high - dimensional datasets ..
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several machine learning techniques such as deep neural networks or association rule mining are useful for this purpose but may require significant computational time when discovering relationships between labels and large arbitrary combinations of numeric dimensions
. moreover , in many application domains , high - dimensional data analysis requires interactive analysis and decision making by a domain expert to specify the rules between the labels and the numeric values .
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Suppose that you have an abstract for a scientific paper: we prove that the real four - dimensional euclidean noncommutative @xmath0-model is renormalisable to all orders in perturbation theory . compared with the commutative case
, the bare action of relevant and marginal couplings contains necessarily an additional term : an harmonic oscillator potential for the free scalar field action .
this entails a modified dispersion relation for the free theory , which becomes important at large distances ( uv / ir - entanglement ) .
the renormalisation proof relies on flow equations for the expansion coefficients of the effective action with respect to scalar fields written in the matrix base of the noncommutative @xmath1 .
the renormalisation flow depends on the topology of ribbon graphs and on the asymptotic and local behaviour of the propagator governed by orthogonal meixner polynomials . .
And you have already written the first three sentences of the full article: noncommutative @xmath0-theory is widely believed to be not renormalisable in four dimensions . to underline the belief one usually draws the non - planar one - loop two - point function resulting from the noncommutative @xmath0-action .
the corresponding integral is finite , but behaves @xmath2 for small momenta @xmath3 of the two - point function .
the finiteness is important , because the @xmath3-dependence of the non - planar graph has no counterpart in the original @xmath0-action , and thus ( if divergent ) can not be absorbed by multiplicative renormalisation ..
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however , if we insert the non - planar graph declared as finite as a subgraph into a bigger graph , one easily builds examples ( with an arbitrary number of external legs ) where the @xmath4 behaviour leads to non - integrable integrals at small inner momenta .
this is the so - called uv / ir - mixing problem @xcite .
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Suppose that you have an abstract for a scientific paper: we present for the first time metallicity maps generated using data from the wide field spectrograph ( wifes ) on the anu 2.3 m of 9 luminous infrared galaxies ( lirgs ) and discuss the abundance gradients and distribution of metals in these systems .
we have carried out optical integral field spectroscopy ( ifs ) of several several lirgs in various merger phases to investigate the merger process . in a major merger of two spiral galaxies with preexisting disk abundance gradients
, the changing distribution of metals can be used as a tracer of gas flows in the merging system as low metallicity gas is transported from the outskirts of each galaxy to their nuclei .
we employ this fact to probe merger properties by using the emission lines in our ifs data to calculate the gas - phase metallicity in each system .
we create abundance maps and subsequently derive a metallicity gradient from each map .
we compare our measured gradients to merger stage as well as several possible tracers of merger progress and observed nuclear abundances .
we discuss our work in the context of previous abundance gradient observations and compare our results to new galaxy merger models which trace metallicity gradient .
our results agree with the observed flattening of metallicity gradients as a merger progresses .
we compare our results with new theoretical predictions that include chemical enrichment .
our data show remarkable agreement with these simulations . .
And you have already written the first three sentences of the full article: galaxy collisions and mergers represent a key stage in the evolution of galaxies in the local universe and beyond . throughout cosmic time gravitational forces have assembled ever larger galactic systems from the collisions and mergers of smaller fragments . beginning with the theoretical @xcite sequence of merging galaxies , theoretical modeling of massive ,
merging galaxies now includes detailed physics , allowing us to make predictions about galaxy evolution over cosmic time .
the history of chemical enrichment is tied to both star formation and the dynamic redistribution of gas throughout the lifetime of a galaxy and is drastically modified by galaxy merger events @xcite ..
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theory predicts that major mergers encourage the formation of bars in the stellar and gas disks , which induce vigorous gas inflows as the gas looses angular momentum to the stellar component @xcite .
these inflows are thought to be responsible for fueling a massive central starburst and feeding agn and/or quasar activity @xcite . for a spiral galaxy with a preexisting metallicity gradient gas inflow flattens the gradient by diluting the higher abundance gas in the central regions with the lower abundance gas from the outer parts of the galaxy @xcite .
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Suppose that you have an abstract for a scientific paper: the coulomb gap observed in tunneling between parallel two - dimensional electron systems , each at half filling of the lowest landau level , is found to depend sensitively on the presence of an in - plane magnetic field . especially at low electron density ,
the width of the coulomb gap at first increases sharply with in - plane field , but then abruptly levels off .
this behavior appears to coincide with the known transition from partial to complete spin polarization of the half - filled lowest landau level .
the tunneling gap therefore opens a new window onto the spin configuration of two - dimensional electron systems at high magnetic field . .
And you have already written the first three sentences of the full article: in the presence of a large perpendicular magnetic field , coulomb interactions between electrons confined to a two - dimensional plane compete with disorder in determining the system s physical properties . in the clean limit interactions dominate and give rise to a wealth of exotic collective states , including both compressible and incompressible quantum liquids , various solid phases , and quantum nematic liquid crystals @xcite
. moreover , the relatively small spin zeeman energy in typical two - dimensional electron systems ( 2des ) can be so overwhelmed by these interactions that ground state spin configurations which defy simple pauli counting rules can be stabilized @xcite .
these unusual spin configurations have been detected and studied experimentally by various means , including conventional electrical transport , photo - luminescence and inelastic light scattering , nuclear magnetic resonance , etc . @xcite ..
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the effects of coulomb interactions on 2d electron systems at high magnetic field are most dramatically illustrated by the numerous fractional quantized hall effect states @xcite and the emergent gapless metallic phases of composite fermions ( cfs ) @xcite , all of which exist at specific fractional fillings of the landau levels created by the magnetic field .
nevertheless , these exotic phenomena actually represent relatively subtle variations in the strong electronic correlations that exist throughout the high field regime .
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Suppose that you have an abstract for a scientific paper: we investigate the possibility of the existence of nonsparse strongly summable ultrafilters on certain abelian groups .
in particular , we show that every strongly summable ultrafilter on the countably infinite boolean group is sparse .
this answers a question of hindman , steprns and strauss . .
And you have already written the first three sentences of the full article: the concept of the stone - ech compactification of a semigroup has become one of central importance , and has been studied extensively . throughout this paper , we think of the stone - ech compactification of a discrete abelian semigroup @xmath0 as the set @xmath1 of ultrafilters on @xmath0 , where the point @xmath2 is identified with the principal ultrafilter @xmath3 , and the basic open sets are those of the form @xmath4 , for @xmath5 .
then these sets are actually clopen , and @xmath6 is really the closure in @xmath1 of the set @xmath7 , regarded as a subset of @xmath1 under the aforementioned identification of points in @xmath0 with principal ultrafilters . the semigroup operation @xmath8 on @xmath0 is also extended by the formula @xmath9 which turns @xmath1 into a right topological semigroup , meaning that for each @xmath10 the mapping @xmath11 is continuous ( note that the extended operation @xmath8 need not be commutative , and , even if @xmath0 is a group , elements @xmath12 do not necessarily have inverses ) .
the details of this construction ( as well as a lot more information , along with applications ) can be seen in @xcite . in this paper.
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, we will focus mainly on the case when @xmath0 is a group .
the lowercase roman letters @xmath13 are reserved for ultrafilters , while the uppercase roman letters @xmath14 , with or without subscripts , will always denote subsets of the abelian group at hand .
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Suppose that you have an abstract for a scientific paper: superfluid @xmath0he - a has domain - wall - like structures , which are called solitons .
we calculate numerically the structure of a splay soliton .
we study the effect of solitons on the nuclear - magnetic - resonance spectrum by calculating the frequency shifts and the amplitudes of the soliton peaks for both longitudinal and transverse oscillations of magnetization . the effect of dissipation caused by normal - superfluid conversion and spin diffusion is calculated .
the calculations are in good agreement with experiments , except a problem in the transverse resonance frequency of the splay soliton or in magnetic - field dependence of reduced resonance frequencies . .
And you have already written the first three sentences of the full article: nuclear magnetic resonance ( nmr ) has turned out to be very useful for studying the superfluid phases of liquid @xmath0he .
the two superfluid phases a and b are distinguished in the nmr spectrum by different frequency shifts of the absorption peaks.@xcite in addition to these `` bulk '' peaks , one often observes additional `` satellite '' peaks .
these are caused by topological objects and textures that appear in the superfluid order parameter . especially in superfluid @xmath0he - a ,.
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several different objects have been identified based on the frequency shifts of the satellite peaks.@xcite the simplest of these are solitons .
they are domain - wall - like structures where a planar object separates two different but degenerate bulk states .
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Suppose that you have an abstract for a scientific paper: the status of light @xmath0 , @xmath1 and @xmath2 mesons is discussed , particularly the separation of @xmath3 and @xmath4 states .
they fall into a simple scheme except for @xmath5 . a case
is made that this has been confused with the @xmath6 .
it should be possible to check this with existing or forthcoming data . * light @xmath7 and @xmath2 mesons * .
And you have already written the first three sentences of the full article: the objective of this paper is a critical review of the identification of light mesons with @xmath8 = @xmath7 and @xmath2 , particularly the separation of @xmath7 states into @xmath9 and @xmath4 .
that detail is important in its own right .
it will also be vital input information into the search for the @xmath7 glueball in radiative @xmath10 decays ..
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it is unrealistic that those data will be extensive enough to sort out the complex spectroscopy of @xmath11 states as well as glueballs .
section 2 reviews @xmath7 states .
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Suppose that you have an abstract for a scientific paper: we present data from high - dispersion echelle spectra and simultaneous @xmath0 photometry for @xmath1 doradus .
these data were obtained from several sites during 1994 november as part of the musicos-94 campaign .
the star has two closely - spaced periods of about 0.75 d and is the brightest member of a new class of variable early f - type stars . a previously suspected third period , very close to the other two , is confirmed .
previous observations indicated that sudden changes could be expected in the spectrum , but none were found during the campaign .
the radial velocities rule out the possibility of a close companion .
the phasing between the radial velocity and light curve of the strongest periodic component rules out the starspot model .
the only viable mechanism for understanding the variability is nonradial pulsation .
we used the method of moments to identify the modes of pulsation of the three periodic components .
these appear to be sectorial retrograde modes with spherical harmonic degrees , ( @xmath2 ) , as follows : @xmath3 = ( 3,3 ) , @xmath4 = ( 1,1 ) and @xmath5 = ( 1,1 ) .
the angle of inclination of the star is found to be @xmath6 .
stars : pulsation - stars : variables - stars : individual : @xmath1 dor . .
And you have already written the first three sentences of the full article: @xmath1 doradus ( f0v ) is the brightest member of what appears to be a new class of pulsating variable stars . in recent years , a number of late a- and early f - type dwarfs have been found to be variable with periods of the order of one day ( see krisciunas & handler , 1995 for a list )
this is too long for membership of the @xmath7 scuti class , where the periods are just a few hours .
the period is , in many cases , compatible with that expected for rotation , which suggests that the variability may be due to the rotation of a spotted star ( mantegazza , poretti & zerbi 1994 ) ..
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however , most stars appear to be multiperiodic and require improbably large differential rotation .
the starspot model for @xmath1 dor has been examined by balona , krisciunas & cousins ( 1994b ) who find that large overlapping spots would be required to give the observed light and colour amplitudes .
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Suppose that you have an abstract for a scientific paper: we show that a forward jet with large transverse momentum in an onium - onium collision is a hard probe which can be effectively characterized by a colour - dipole distribution at the time of the interaction .
the dipole distribution is computed , and compared to its counterpart for a virtual photon in the initial state .
we find that while in the photon case , the tail of large sizes is exponentially cut - off , it contributes sizeably in the forward - jet case , which signs the sensitivity of observables based on such events to the infrared region .
moreover , a direct probabilistic interpretation of the dipole distribution fails since it takes negative values in the large size region . .
And you have already written the first three sentences of the full article: the physics at hera has proved the successes of ( resummed ) perturbative qcd in describing many observables accurately measured there : inclusive ones like the structure function @xmath0 , but also more exclusive ones , like the diffractive structure function @xmath1 , or heavy meson production .
the justification for relying on a perturbative development is that the deep - inelastic scattering process naturally provides a well - controlled hard scale given by the photon virtuality @xmath2 , which makes the effective strong coupling constant @xmath3 small enough . on the one hand ,
the physics of these observables is usually well described by the renormalization group evolution @xcite between a lower scale @xmath4 at which the proton parton densities are parametrized and the scale @xmath2 . on the other hand ,.
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the cross - section for the events selected with the requirement that a forward jet of transverse momentum @xmath5 of the order of @xmath2 be present in the final state is seemingly not described by a straightforward dglap evolution ( see ref.@xcite and references therein ) : as a matter of fact , these regge - like kinematics are expected to select the bfkl dynamics @xcite . in @xmath6 collisions at the tevatron ,
no hard scale is provided by the initial state .
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Suppose that you have an abstract for a scientific paper: troubleshooting systems is integral to experimental physics in both research and instructional laboratory settings .
the recently adopted aapt lab guidelines identify troubleshooting as an important learning outcome of the undergraduate laboratory curriculum .
we investigate students model - based reasoning on a troubleshooting task using data collected in think - aloud interviews during which pairs of students attempted to diagnose and repair a malfunctioning circuit .
our analysis scheme is informed by the experimental modeling framework , which describes physicists use of mathematical and conceptual models when reasoning about experimental systems . we show that this framework is a useful lens through which to characterize the troubleshooting process . .
And you have already written the first three sentences of the full article: instructional physics laboratories are well - situated to promote student competence in physics practices , yet few studies focus on such environments especially at the upper - division level @xcite . recently , the american association of physics teachers ( aapt ) identified modeling as a major focus area for learning outcomes in undergraduate laboratory courses @xcite , consistent with model - based efforts in introductory instruction @xcite . over the last few years
, we have developed the experimental modeling framework ( emf ) to inform curricular transformation of upper - division laboratory courses @xcite .
the emf describes the process through which physicists iteratively revise system models , physical apparatus , and measurement tools in response to discrepant measurements and predictions ..
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the growing emphasis on modeling warrants continued application of the emf to a broad range of upper - division instructional laboratory contexts .
previous work demonstrated the utility of the emf as a tool for characterizing students model - based reasoning , focusing on an optical physics context @xcite . in the present work
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Suppose that you have an abstract for a scientific paper: the leading twist theory of nuclear shadowing predicts the shadowing correction to nuclear parton distributions at small @xmath0 by connecting it to the leading twist hard diffraction in electron - nucleon scattering .
the uncertainties of the predictions are related to the shadowing effects resulting from the interaction of the hard probe with @xmath1 nucleons .
we argue that the pattern of hard diffraction observed at hera allows one to reduce these uncertainties .
we develop a new approach to the treatment of these multiple interactions , which is based on the concept of the color fluctuations and accounts for the presence of both point - like and hadron - like configurations in the virtual photon wave function . using the developed framework
, we update our predictions for the leading twist nuclear shadowing in nuclear parton distributions of heavy nuclei at small @xmath0 . .
And you have already written the first three sentences of the full article: in this work , we consider the quark and gluon parton distribution functions ( pdfs ) in nuclei at small values of bjorken @xmath0 and their reduction as compared with the incoherent sum of the nucleon pdfs because of the phenomenon of nuclear shadowing .
most of experimental information on nuclear pdfs comes from inclusive deep inelastic scattering ( dis ) with nuclear targets which measures the nuclear structure function @xmath2 . for @xmath3 , @xmath4 , which is called nuclear shadowing [
@xmath5 is the isoscalar nucleon structure function and @xmath6 is the number of nucleons ] ..
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because of the factorization theorem for dis ( for a review , see ref .
@xcite ) , which relates @xmath2 to nuclear parton distributions @xmath7
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Suppose that you have an abstract for a scientific paper: we investigate the computational efficiency of two stochastic based alternatives to the sequential propagator method used in lattice qcd calculations of heavy - light semileptonic form factors . in the first method , we replace the sequential propagator , which couples the calculation of two of the three propagators required for the calculation , with a stochastic propagator so that the calculations of all three propagators are independent .
this method is more flexible than the sequential propagator method but introduces stochastic noise .
we study the noise to determine when this method becomes competitive with the sequential propagator method , and find that for any practical calculation it is competitive with or superior to the sequential propagator method .
we also examine a second stochastic method , the so - called one - end trick " , concluding it is relatively inefficient in this context .
the investigation is carried out on two gauge field ensembles , using the non - perturbatively improved wilson - sheikholeslami - wohlert action with @xmath0 mass - degenerate sea quarks .
the two ensembles have similar lattice spacings but different sea quark masses .
we use the first stochastic method to extract @xmath1-improved , matched lattice results for the semileptonic form factors on the ensemble with lighter sea quarks , extracting @xmath2 . .
And you have already written the first three sentences of the full article: experimental measurements of heavy - light semileptonic decays , combined with theoretical input , can be used to extract the cabibbo - kobayashi - maskawa ( ckm ) matrix elements @xmath3 , @xmath4 , @xmath5 , and @xmath6 .
the determination of these matrix elements provides constraints on the ckm unitarity triangle and thus tests the standard model .
conversely , @xmath5 and @xmath6 are known with high precision , and can be used to test the lattice techniques involved in calculating the decay rates of @xmath7 mesons ..
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recent progress reports of current @xmath7 meson semileptonic decay calculations are presented in refs .
the most recent study where systematic errors are taken into account was presented in ref .
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Suppose that you have an abstract for a scientific paper: we show that the metric ( line element ) is the first geometrical object to be associated to a discrete ( quantum ) structure of the spacetime without necessity of black hole - entropy - area arguments , in sharp contrast with other attempts in the literature . to this end ,
an emergent metric solution obtained previously in [ physics letters b 661 , 186 - 191 ( 2008 ) ] from a particular non - degenerate riemmanian superspace is introduced .
this emergent metric is described by a physical coherent state belonging to the metaplectic group @xmath0 with a poissonian distribution at lower @xmath1 ( number basis ) restoring the classical thermal continuum behaviour at large @xmath1 ( @xmath2 , or leading to non - classical radiation states , as is conjectured in a quite general basis by mean the bekenstein - mukhanov effect .
group - dependent conditions that control the behavior of the macroscopic regime spectrum ( thermal or not ) , as the relationship with the problem of area / entropy of the black hole are presented and discussed . .
And you have already written the first three sentences of the full article: the unification of gravity and quantum theory is one of the great challenges of physics .
the last years were dominated by attempts to reach this goal by rather radical new concepts , as is exemplified by the string theory and loop quantum gravity .
then , one of the main points treated in the current literature is the close relation between the quantum structure of the spacetime and its discretization at particular scale . in the pioneering works of the last century ,.
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the concept of fundamental scale was associated to the minimal length or , geometrically speaking , to the metric ( e.g.through the line element describing the spacetime ) .
actually , contrarily to these prior investigations , arguments favoring the use of the area as a fundamental entity were appearing in recent years .
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Suppose that you have an abstract for a scientific paper: we present evidence to suggest that the study of one dimensional quasi - exactly solvable ( qes ) models in quantum mechanics should be extended beyond the usual @xmath0 approach .
the motivation is twofold : we first show that certain quasi - exactly solvable potentials constructed with the @xmath0 lie algebraic method allow for a new larger portion of the spectrum to be obtained algebraically .
this is done via another algebraization in which the algebraic hamiltonian can not be expressed as a polynomial in the generators of @xmath0 .
we then show an example of a new quasi - exactly solvable potential which can not be obtained within the lie - algebraic approach . .
And you have already written the first three sentences of the full article: lie - algebraic and lie group theoretic methods have played a significant role in finding exact solutions to the schrdinger equation in quantum mechanics . in the classical applications
, the lie group appears as a symmetry group of the hamiltonian operator , and the associated representation theory provides an algebraic means for computing the spectrum .
of particular importance are the exactly solvable problems , such as the harmonic oscillator or the hydrogen atom , whose point spectrum can be completely determined using purely algebraic methods . the concept of a _.
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spectrum generating algebra _ dates back to a paper by goshen and lipkin @xcite , and was later rediscovered in the context of high energy physics by two different groups @xcite .
the study of spectrum generating algebras received much impetus in the subsequent years ( see the review @xcite ) and it was soon applied also in the field of molecular dynamics by iachello , levine , alhassid , grsey and their collaborators ( see the book @xcite for a survey of theory and applications ) .
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Suppose that you have an abstract for a scientific paper: we report on high spatial resolution observations , using the australia telescope compact array ( atca ) , of ground - state oh masers .
these observations were carried out toward 196 pointing centres previously identified in the southern parkes large - area survey in hydroxyl ( splash ) pilot region , between galactic longitudes of @xmath0 and @xmath1 and galactic latitudes of @xmath2 and @xmath3 .
supplementing our data with data from the magmo ( mapping the galactic magnetic field through oh masers ) survey , we find maser emission towards 175 of the 196 target fields .
we conclude that about half of the 21 non - detections were due to intrinsic variability . due to the superior sensitivity of the follow - up atca observations , and the ability to resolve nearby sources into separate sites
, we have identified 215 oh maser sites towards the 175 fields with detections . among these 215 oh maser sites ,
111 are new detections . after comparing the positions of these 215 maser sites to the literature
, we identify 122 ( 57 per cent ) sites associated with evolved stars ( one of which is a planetary nebula ) , 64 ( 30 per cent ) with star formation , two sites with supernova remnants and 27 ( 13 per cent ) of unknown origin .
the infrared colors of evolved star sites with symmetric maser profiles tend to be redder than those of evolved star sites with asymmetric maser profiles , which may indicate that symmetric sources are generally at an earlier evolutionary stage . .
And you have already written the first three sentences of the full article: ground - state ( @xmath4 , @xmath5 ) hydroxyl ( oh ) masers were first discovered towards several galactic hiiregions ( e.g. w3(oh ) ) by @xcite and @xcite . since their discovery , extensive work on ground - state oh masers
has shown that they are commonly associated with regions of high - mass star formation ( hmsf ) ( @xcite ; @xcite ) and these masers are predominantly strong in main - line transitions ( @xmath6 , @xmath7 ) ( i.e. 1665mhz and 1667mhz ; @xcite ) .
@xcite compiled a catalog of @xmath8375 ground - state oh maser sites associated with hmsf from the literature , representing an up to date compilation of this category of sources ..
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ground - state oh masers are also detected towards circumstellar envelopes of evolved giant and supergaint stars , such as miras and oh / ir stars ( @xcite ; @xcite , @xcite , @xcite ) , and are typically dominated by emission from the 1612 mhz satellite line ( i.e. @xmath9 , 1612mhz ; @xcite ) .
the maser emission in the 1720mhz satellite - line transition ( @xmath10 ) , is usually associated with supernova remnants ( snrs ) ( @xcite ) and traces the interaction between snrs and surrounding dense molecular clouds .
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Suppose that you have an abstract for a scientific paper: we discuss the prospects for parity non - conservation experiments with highly charged heavy ions .
energy levels and parity mixing for heavy ions with two to five electrons are calculated .
we investigate two - photon - transitions and the possibility to observe interference effects between weak - matrix elements and stark matrix elements for periodic electric field configurations . plus 12pt minus 1pt plus 1pt pacs numbers : 32.30.-r , 35.10.wb , 32.90.+a uftp preprint 408/1996 .
And you have already written the first three sentences of the full article: atomic physics tests of the standard model @xcite play a very special role because of the small momentum transfers involved .
comparisons between their results and high energy data are highly sensitive to radiative corrections and thus to extensions of the standard model @xcite . with the percent precision reached in the cs experiments described in @xcite , the effect of radiative corrections
is of the order of the experimental accuracy ..
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if a system is found for which a 0.1% accuracy can be reached the experimental results would allow most interesting and far reaching conclusions ( see e.g. @xcite ) . for the atoms and experimental setups studied so far this seems unluckily to be out of reach , which motivates the search for significantly different alternatives .
the possibility we want to discuss is the use of highly charged heavy ions , which can be produced and stored in great variety at , e.g. , gesellschaft fr schwerionenforschung in darmstadt , germany .
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Suppose that you have an abstract for a scientific paper: the theoretical analysis of @xmath0 correlation function in 10% most central au+au collisions at rhic energy @xmath1 gev shows that the contribution of residual correlations is the necessary factor to obtain a satisfactory description of the experimental data .
a neglecting of the residual correlation effect , leads to unrealistically low source radius , about 2 times smaller than the corresponding value for @xmath2 case , when one fits the experimental correlation function within lednick - lyuboshitz analytical model .
recently an approach accounting effectively for residual correlations for the baryon - antibaryon correlation function was proposed , and a good rhic data description was reached with the source radius extracted from the hydrokinetic model ( hkm ) . the @xmath3 scattering length , as well as the parameters characterizing the residual correlation effect annihilation dip amplitude and its inverse width were extracted from the corresponding fit . in this paper
we use these extracted values and simulated in hkm source functions for pb+pb collisions at the lhc energy @xmath4 tev to predict the corresponding @xmath5 and @xmath6 correlation functions .
keywords : _ final state interaction , baryons , lead - lead collisions , lhc , residual correlations _ .
And you have already written the first three sentences of the full article: the study of @xmath7 correlation functions ( cf ) ( along with the study of other two - particle correlations such as @xmath8 , @xmath9 ) allows one to obtain the information about the character of evolution of the matter formed in relativistic nuclear collisions , in particular about the character of collective flow .
another great possibility which is open for a researcher in baryon-(anti)baryon correlation analysis is the study of strong interaction between the particles of different sorts with final state interaction ( fsi ) correlation technique @xcite . since lhc produces copiously hadrons of different species , including multi - strange , charmed and beauty ones , the advantage of this approach is the ability to analyze the interactions even in exotic particle pairs , hardly achieved by other means .
fitting the experimental correlation function with some analytical formula , e. g. lednick - lyuboshitz model @xcite , allows one to extract the quantities describing both the interaction in corresponding pairs and the particle emission region size ..
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of course , if the source function @xmath10 , describing the spatial structure of the pair emission , is known , an extraction of unknown interaction parameters becomes more reliable . the corresponding spatial structure can be obtained from realistic collision model that simulates the evolution of the system formed in high energy heavy ion collisions . in the recent paper @xcite the hybrid variant of the hydrokinetic model ( hkm ) @xcite
was used for this purpose .
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Suppose that you have an abstract for a scientific paper: the presence of outliers in financial asset returns is a frequently occuring phenomenon and may lead to unreliable mean - variance optimized portfolios .
this fact is due to the unbounded influence that outliers can have on the mean returns and covariance estimators that are inputs in the optimization procedure . in the present paper
we consider new robust estimators of location and covariance obtained by minimizing an empirical version of a pseudodistance between the assumed model and the true model underlying the data .
we prove statistical properties of the new mean and covariance matrix estimators , such as affine equivariance , b - robustness and efficiency .
these estimators can be easily used in place of the classical estimators , thereby providing robust optimized portfolios . a monte carlo simulation study and an application to real data
show the advantages of the proposed approach .
robustness and sensitivity analysis , portfolio optimization .
And you have already written the first three sentences of the full article: since markowitz ( 1952 ) formulated the idea of diversification of investments , the mean - variance approach has been widely used in practice in asset allocation and portfolio management , despite many sophisticated models proposed in literature . on the other hand , some drawbacks of the standard markowitz approach are reported in literature ( michaud ( 1989 ) ) .
one of the critical weaknesses of the classical mean - variance analysis is its lack of robustness . since the classical estimators of the mean and the covariance matrix , which are inputs in the optimization procedure , are very sensitive to the presence of gross errors or atypical events in data , the weights of the resulted portfolio , which are outputs of this procedure , can be drastically affected by these atypical data
this fact was proved by perret - gentil and victoria - feser ( 2005 ) by using the influence function approach ..
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also , some other recent papers underline this idea and show that the large or small values of asset returns can have an abnormally large influence on the estimations leading to portfolio that are far to be optimal ( grossi and laurini ( 2011 ) ) . in order to remove this drawback and to construct portfolios
not overly affected by deviations of the data from the assumed model , many methods have been proposed in literature . for an overview on the methods used for robust portfolio optimization we refer to fabozzi et al .
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Suppose that you have an abstract for a scientific paper: heavy quarkonia production is predicted to be sensitive to the formation of the quark gluon plasma in relativistic heavy ion collisions via competing mechanisms such as color screening and/or quark recombination . during 2004 and 2005
rhic data taking periods , the phenix collaboration has measured @xmath0 decay into lepton pairs both at mid and forward rapidity in au+au and cu+cu collisions at @xmath1 gev .
we present the @xmath0 nuclear modification factor and the @xmath0 mean square transverse momentum as a function of the collision centrality for both systems , as well as the rapidity dependence of the @xmath0 yield for different centrality classes .
it is compared to different theoretical predictions .
all au+au and cu+cu results shown here are preliminary . .
And you have already written the first three sentences of the full article: it has been established at lower energies that the @xmath0s created in nuclear collisions are suppressed when the system size and the centrality of the collision increase @xcite . for heavy enough nuclei
the suppression exceeds the _ normal _ nuclear absorption observed with light nuclei .
several mechanisms , including color screening in the quark gluon plasma , have been proposed to explain this _ abnormal _ suppression observed at low energy ..
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measurements performed at higher energy are therefore crucial to constrain the models and discriminate between them .
moreover they may uncover new mechanisms such as quark recombination .
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Suppose that you have an abstract for a scientific paper: the second - order phase transition into a hidden order phase in uru@xmath0si@xmath0 goes along with an order parameter which is still a mystery , despite 30 years of research .
however , it is understood that the symmetry of the order parameter must be related to the symmetry of the low lying local electronic @xmath1-states . here
we present results of a novel spectroscopy , namely core - level non - resonant inelastic x - ray scattering ( nixs ) .
this method allows for the measurement of local high - multipole excitations and it is bulk sensitive .
the observed anisotropy of the scattering function unambiguously shows that the 5@xmath1 ground state wave function is composed mainly , but essentially not purely , of the @xmath2 with majority @xmath3=@xmath4+@xmath5 and/or @xmath6 singlet states . .
And you have already written the first three sentences of the full article: the hidden order problem in uru@xmath0si@xmath0 is an unanswered question in the field of strongly correlated electron materials .
although it is studied since several decades there is still no consensus about how this new phase forms .
understanding the hidden order phase formation is not only an intellectual problem , it will also advance concepts for designing quantum materials with new exotic properties ..
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many hidden order scenarios are based on the assumption of certain ground state symmetries and the present study addresses this aspect . a novel spectroscopic technique , non - resonant inelastic x - ray scattering ( nixs ) , that has become available thanks to high brilliance synchrotrons , allows to measure directly in a bulk sensitive experiment the symmetry of the 5@xmath1 ground state wave function in uru@xmath0si@xmath0 . in heavy fermion rare earth or actinide compounds , the @xmath1 electrons are well localized at high temperatures , but as temperature is lowered hybridization with conduction electrons becomes increasingly effective , resulting in a more itinerant @xmath1-electron character at low temperatures .
these hybridized @xmath1 electrons form narrow bands and have large effective masses .
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Suppose that you have an abstract for a scientific paper: while evaporating solvent is a widely used technique to assemble nano - sized objects into desired superstructures , there has been limited work on how the assembled structures are affected by the physical aspects of the process .
we present large scale molecular dynamics simulations of the evaporation - induced assembly of nanoparticles suspended in a liquid that evaporates in a controlled fashion .
the quality of the nanoparticle crystal formed just below the liquid / vapor interface is found to be better at relatively slower evaporation rates , as less defects and grain boundaries appear .
this trend is understood as the result of the competition between the accumulation and diffusion times of nanoparticles at the liquid / vapor interface . when the former is smaller , nanoparticles are deposited so fast at the interface that they do not have sufficient time to arrange through diffusion , which leads to the prevalence of defects and grain boundaries .
our results have important implications in understanding assembly of nanoparticles and colloids in non - equilibrium liquid environments .
* i. introduction * large , defect - free crystalline arrays of nanoparticles ( nps ) are critical for many technologically important ultra thin film materials including filters , sensors , optical devices , and magnetic storage media.@xcite one common method for dispersing nanoparticles is to suspend them in solution , spread the suspension on a surface , and then evaporate the solvent.@xcite this technique has been used to assemble nps into desired structures such as nanoclusters , rings , wires , stripes , films , and superlattices .
@xcite the factors that influence the assembled structure include the evaporation kinetics of the solvent , the flow properties and concentration of nps in the solution , the np - np interactions , the interactions between nps and the liquid / vapor interface , and the wetting / dewetting behavior of the suspension on the solid surface.@xcite one ubiquitous example is the....
And you have already written the first three sentences of the full article: this research used resources of the national energy research scientific computing center ( nersc ) , which is supported by the office of science of the united states department of energy under contract no .
de - ac02 - 05ch11231 , and the oak ridge leadership computing facility located in the national center for computational sciences at oak ridge national laboratory , which is supported by the office of science of the united states department of energy under contract no .
de - ac05 - 00or22725 ..
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these resources were obtained through the advanced scientific computing research ( ascr ) leadership computing challenge ( alcc ) .
this work is supported by the laboratory directed research and development program at sandia national laboratories .
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Suppose that you have an abstract for a scientific paper: we study the evolution of dwarf ( @xmath0 @xmath1 10@xmath2 l@xmath3 ) star forming and quiescent galaxies in the virgo cluster by comparing their uv to radio centimetric properties to the predictions of multizone chemo - spectrophotometric models of galaxy evolution especially tuned to take into account the perturbations induced by the interaction with the cluster intergalactic medium .
our models simulate one or multiple ram pressure stripping events and galaxy starvation .
models predict that all star forming dwarf galaxies entering the cluster for the first time loose most , if not all , of their atomic gas content , quenching on short time scales ( @xmath4 150 myr ) their activity of star formation .
these dwarf galaxies soon become red and quiescent , gas metal - rich objects with spectrophotometric and structural properties similar to those of dwarf ellipticals .
young , low luminosity , high surface brightness star forming galaxies such as late - type spirals and bcds are probably the progenitors of relatively massive dwarf ellipticals , while it is likely that low surface brightness magellanic irregulars evolve into very low surface brightness quiescent objects hardly detectable in ground based imaging surveys .
the small number of dwarf galaxies with physical properties intermediate between those of star forming and quiescent systems is consistent with a rapid ( @xmath1 1 gyr ) transitional phase between the two dwarf galaxies populations .
these results , combined with statistical considerations , are consistent with the idea that most of the dwarf ellipticals dominating the faint end of the virgo luminosity function were initially star forming systems , accreted by the cluster and stripped of their gas by one or subsequent ram pressure stripping events . .
And you have already written the first three sentences of the full article: dwarf galaxies ( @xmath5 - 18 ) are the most common objects in the nearby universe ( ferguson & binggeli 1994 ) .
their importance resides in the fact that they represent in cold dark matter models the building blocks of hierarchical galaxy formation ( e.g. white & rees 1978 , white & frenk 1991 ) .
their study is thus fundamental for constraining models of galaxy formation and evolution ..
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+ observations of dwarf galaxies , necessarily limited to the nearby universe , revealed however a more complex origin than that predicted by models , making this class of galaxies even more interesting . among dwarf galaxies , dwarf ellipticals ( de ) and the less luminous dwarf spheroidals ( dsph )
are more common than star forming i m and bcds ( ferguson & binggeli 1994 ) .
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Suppose that you have an abstract for a scientific paper: in this paper we study the mapping properties of the averaging operator over a variety given by a system of homogeneous equations over a finite field . we obtain optimal results on the averaging problems over two dimensional varieties whose elements are common solutions of diagonal homogeneous equations . the proof is based on a careful study of algebraic and geometric properties of such varieties . in particular
, we show that they are not contained in any hyperplane and are complete intersections .
we also address partial results on averaging problems over arbitrary dimensional homogeneous varieties which are smooth away from the origin . .
And you have already written the first three sentences of the full article: analysis in finite fields is a useful subject because it interacts with other mathematical fields . in addition
, the finite field case serves as a typical model for the euclidean case and possesses structural advantages which enable us to relate our problems to other well - studied problems in number theory , arithmetic combinatorics , or algebraic geometry . for these reasons , problems in euclidean harmonic analysis
have been recently reformulated and studied in the finite field setting ..
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for example , see @xcite and references therein . in this paper
we investigate @xmath0 estimates of averaging operators over algebraic varieties given by a system of homogeneous polynomials in finite fields . for euclidean averaging problems
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Suppose that you have an abstract for a scientific paper: in this paper we discuss the uniaxial propagation of transient waves within a semi - infinite viscoelastic bessel medium .
first , we provide the analytic expression for the response function of the material as we approach the wave - front .
to do so , we take profit of a revisited version of the so called buchen - mainardi algorithm .
secondly , we provide an analytic expression for the long time behavior of the response function of the material .
this result is obtained by means of the tauberian theorems for the laplace transform .
finally , we relate the obtained results to a peculiar model for fluid - filled elastic tubes . .
And you have already written the first three sentences of the full article: in this paper we deal with a semi - infinite ( @xmath0 ) homogeneous and isotropic viscoelastic medium of density @xmath1 , which is assumed to be at rest for @xmath2 . for @xmath3 , the accessible extremum of the body ( defined by @xmath4 )
is subjected to a perturbation denoted by @xmath5 . here , we are interested in the solution of the wave equation for the response function of the material @xmath6 . in the framework of a linear theory , this problem can be analyzed by working in either the creep or the relaxation representation .
indeed , it is known that a linear viscoelastic body is featured by either the creep compliance ( the strain response to a step input stress ) or the relaxation modulus ( the stress response to a step input of strain ) , for further details see @xcite ..
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we fourther assume that the dynamics of the material is described in terms of a given bessel model of order @xmath7 ( see @xcite ) .
for such a model one has that the dynamical equation for the response function @xmath8 , in the creep representation , is given by @xmath9 \ ,
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Suppose that you have an abstract for a scientific paper: recent results from atlas and cms point to a narrow range for the higgs mass : @xmath0~{\rm gev}$ ] . given this range , a case may be made for new physics beyond the standard model ( sm ) because of the resultant vacuum stability problem , i.e. , the sm higgs quartic coupling may run to negative values at a scale below the planck scale .
we study representative minimal extensions of the sm that can keep the sm higgs vacuum stable to the planck scale by introducing new scalar or fermion interactions at the tev scale while solving other phenomenological problems .
in particular , we consider the type - ii seesaw model , which is introduced to explain the non - zero majorana masses of the active neutrinos .
similarly , we observe that if the stability of the sm higgs vacuum is ensured by the running of the gauge sector couplings , then one may require a series of new electroweak multiplets , the neutral component of which can be cold dark matter candidate . stability may also point to a new @xmath1 gauge symmetry , in which the sm higgs carries non - zero charge . .
And you have already written the first three sentences of the full article: in the standard model ( sm ) of particle physics , the higgs field @xcite provides the mechanism of spontaneous electroweak symmetry breaking and the origin of masses of the fundamental particles , but until recently the higgs boson itself left no signal in high - energy collider experiments .
the situation has clearly changed , however , as both the atlas @xcite and cms @xcite collaborations have announced observation of a bosonic particle at about the @xmath2 significance level .
the excess is driven by the two channels with the highest mass resolution @xmath3 and @xmath4 , and the equally sensitive but low resolution @xmath5 channel . assuming the boson spin is shown to be zero.
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, these results will provide conclusive evidence for the discovery of a higgs - like scalar particle with mass @xmath6 for atlas and @xmath7 for cms .
the discovery points to a favored mass range : @xmath8 , which is in agreement with the indirect detections from the electroweak precision constraints , @xmath9 @xcite .
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Suppose that you have an abstract for a scientific paper: we consider first - order differential operators with locally bounded measurable coefficients on vector bundles with measurable coefficient metrics . under a mild set of assumptions ,
we demonstrate the equivalence between the essential self - adjointness of such operators to a negligible boundary property .
when the operator possesses higher regularity coefficients , we show that higher powers are essentially self - adjoint if and only if this condition is satisfied . in the case
that the low - regularity riemannian metric induces a complete length space , we demonstrate essential self - adjointness of the operator and its higher powers up to the regularity of its coefficients .
we also present applications to dirac operators on dirac bundles when the metric is non - smooth . .
And you have already written the first three sentences of the full article: the problem of determining essential self - adjointness of smooth coefficient first - order differential operators , as well as their powers , is an important and well studied topic .
this paper considers similar problems but in the context of non - smooth coefficients .
more precisely , we consider first - order symmetric differential operators @xmath0 , as well as their powers , on smooth vector bundles @xmath1 , over smooth , noncompact manifolds @xmath2 ..
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we allow for the coefficients of the operator as well as the metrics on the bundle and the manifold to be non - smooth .
our primary focus is to understand the relationship between the regularity of the coefficients of @xmath0 and the essential self - adjointness of powers of @xmath0 .
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Suppose that you have an abstract for a scientific paper: we study the phase transition from two different topological phases to the ferromagnetic phase by focusing on points of the phase transition . to this end , we present a detailed mapping from such models to the ising model in a transverse field .
such a mapping is derived by re - writing the initial hamiltonian in a new basis so that the final model in such a basis has a well - known approximated phase transition point
. specifically , we consider the toric codes and the color codes on some various lattices with ising perturbation .
our results provide a useful table to compare the robustness of the topological codes and to explicitly show that the robustness of the topological codes depends on triangulation of their underlying lattices . * on the robustness of topological quantum codes : + ising perturbation + * mohammad hossein zarei + physics department , college of sciences , shiraz university , shiraz 71454 , iran + .
And you have already written the first three sentences of the full article: one of the important problems in the control of quantum systems is the decoherence which emerges from undesirable interactions @xcite .
specially in quantum computation processes , it is very important to find a quantum memory which is robust against emergent errors . in recent years , finding a solution for the decoherence problem has been one of the biggest challenges @xcite .
one of the options to circumvent this problem is topological quantum computation where topological nature of a physical system is used to perform a fault tolerant quantum computation @xcite ..
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+ the key property in the topological quantum computational model is topological order .
topological order is a new phase of matter which for the first time was presented by wen in 1980 @xcite .
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Suppose that you have an abstract for a scientific paper: we present an extensive study of lithium abundances in dwarf components of chromospherically active binary stars ( cabs ) .
since most of these binaries have known radii , masses and ages , this kind of data is especially useful for comparisons with theoretical models which try to explain the li depletion phenomenon .
we show that a significant part of these stars have clear li overabundances with respect to the typical values for stars of the same mass and evolutionary stage .
these excesses are evident when comparing our sample of cabs with binary and single stars belonging to open clusters of different ages , namely pleiades , hyades , ngc752 , m67 and ngc188 , which have ages ranging from 7@xmath010@xmath1 to 10@xmath2 yr .
the li excesses are more conspicuous for masses in the range 0.750.95 m@xmath3 , indicating that the rate of li depletion has been less pronounced in cabs than in single stars .
this phenomenon is interpreted in the context of transport of angular momentum from the orbit to the stellar rotation due to tidal effects .
this angular momentum transfer would avoid the radial differential rotation and the associated turbulent mixing of material in the stellar interior .
other explanations , however , can not be ruled out .
this is the case of transport of material induced by internal gravity waves , which could be inhibited due to the presence of strong magnetic fields associated with the effective dynamo in cabs .
the confirmed existence of a relation between li abundances and the fluxes in caii h&k lines can also be accommodated within both scenarios . .
And you have already written the first three sentences of the full article: the stellar group known as chromospherically active binary stars ( cabs ) is characterized by the presence of cool components which show emissions in caii h&k , h@xmath4 , mgii h&k , cii , civ and other spectral lines .
they have also other special characteristics , such as short orbital periods and high rotational velocities ( strassmeier et al .
1993 ) , and include rs cvn binaries , which contain at least an evolved component , and by dra stars , which are still in the main sequence ( ms ) ..
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this last group comprises young single stars with rapid rotation and close binary stars .
this paper belongs to an ongoing project designed to study the evolution and properties of cabs . in preliminary works ( fernndez figueroa et al .
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Suppose that you have an abstract for a scientific paper: the spin-_1/2 _ @xmath0 heisenberg magnet is considered for the case of the anisotropy parameter tending to infinity ( so - called , _ ising limit _ ) .
a thermal correlation function of the ferromagnetic string is calculated over the ground state .
the approach to the calculation of the correlation functions is based on the observation that the wave function in the limit considered is expressed in terms of the symmetric schur functions .
it is demonstrated that at low temperatures the amplitude of the asymptotical expression of the present correlation function is proportional to the squared numbers of strict boxed plane partitions
. 1.0 cm 1.0 cm .
And you have already written the first three sentences of the full article: the ising model was one of the favorite models of a. n. vassiliev .
his studies were concentrated on the scaling properties of this model @xcite .
it is remarkable that in a special limit of the anisotropy parameter tending to infinity , the hamiltonian of the spin_-1/2 _ heisenberg @xmath0 chain is transformed into the hamiltonian of one - dimensional ising model @xcite ..
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this limit is usually called as the _ ising limit _ of the @xmath0 chain @xcite . in our paper
we shall investigate the ising limit of the @xmath0 magnet using an effective hamiltonian which is commutative with the ising hamiltonian and has a complete system of the eigen - functions which is common with that of the ising hamiltonian .
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Suppose that you have an abstract for a scientific paper: a method to extract primary @xmath0-ray spectra from particle-@xmath0 coincidences at excitation energies up to the neutron binding energy is described . from these spectra , the level density and @xmath0-ray strength function can be determined . from the level density ,
several thermodynamical quantities are obtained within the microcanonical and canonical ensemble . also models for the @xmath0-ray strength function
are discussed .
+ + , m. hjorth - jensen , j. rekstad and s. siem + department of physics , university of oslo , box 1048 blindern , n-0316 oslo , norway + + a. schiller + lawrence livermore national laboratory , livermore , ca-94551 , usa + + a. voinov + frank laboratory of neutron physics , joint institute of nuclear research , 141980 dubna , moscow reg . ,
russia + .
And you have already written the first three sentences of the full article: the oslo cyclotron group has established a method to deduce experimental level densities and @xmath0-ray strength functions @xcite .
these data contain essential information on nuclear structure and thermal and electromagnetic properties . in the last couple of years several fruitful applications of the method have been reported [ 2 - 10 ] .
the most efficient way to create entropy in atomic nuclei is to break @xmath1 nucleon cooper pairs in the core ..
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a beautiful manifestation of pairbreaking is the backbending phenomena in rapidly rotating nuclei . in this work
, the pairbreaking process is studied as function of intrinsic excitation energy ( or temperature ) . of great interest
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Suppose that you have an abstract for a scientific paper: we present a thorough theoretical assessment of the stability of non - collinear spin arrangements in small palladium clusters .
we generally find that ferromagnetic order is always preferred , but that antiferromagnetic and non - collinear configurations of different sorts exist and compete for the first excited isomers .
we also show that the ground state is insensitive to the choice of atomic configuration for the pseudopotential used and to the approximation taken for the exchange and correlation potential .
moreover , the existence and relative stability of the different excited configurations also depends weakly on the approximations employed .
these results provide strong evidence on the transferability of pseudopotential and exchange and correlation functionals for palladium clusters as opposed to the situation found for the bulk phases of palladium .
= 10000 .
And you have already written the first three sentences of the full article: the magnetic properties of free - standing atomic clusters of 3d tm elements have been intensively scrutinized during the last two decades .
two different but related phenomena have specifically been discussed and essentially unravelled .
the first is the modification of local magnetic moments as compared with the values found in bulk materials ..
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the second is the competition between the possible ferromagnetic , antiferromagnetic and non - collinear arrangements of the local spins , as well as its interplay with the geometry of the nanostructure . in the case of ferromagnetic elements like fe , co and ni ,
the increase of the average cluster magnetic moment can be easily explained in terms of the reduced atomic coordination in the low - dimensional regime , with oscillations associated to structural ( symmetry ) changes .
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Suppose that you have an abstract for a scientific paper: we report the higher order moments of the net - charge multiplicity distributions for the au+au collisions at @xmath0= 7.7 , 11.5 , 19.6 , 27 , 39 , 62.4 and 200 gev in the star experiment at the relativistic heavy - ion collider ( rhic ) .
the energy and centrality dependence of higher moments and their products ( such as @xmath1 , @xmath2 and @xmath3 ) are presented .
the data are also compared to poisson expectations and hadron resonance gas model calculations . .
And you have already written the first three sentences of the full article: at extreme high temperature and/or chemical potential , hadronic matter undergoes a phase transition where color degrees of freedom plays important role , known as quark gluon plasma ( qgp ) .
the qcd based model calculations claim that at vanishing baryon chemical potential ( @xmath4 ) the transition is simply a crossover @xcite . at large @xmath4 ,
the phase transition is of first order @xcite ..
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the presence of these two types of transition , at two extreme limit of @xmath4 , urges to have an end point in the first order phase transition in qcd phase diagram , known as the qcd critical point ( cp ) . to probe the cp and
map the phase boundary in phase diagram , the beam energy scan program @xcite has been undertaken with successful data taking in year 2010 and 2011 . the star experiment has collected data for au+au collisions at @xmath0= 7.7 to 200 gev covering large range of @xmath4= 20 to 410 mev @xcite in the phase diagram . + the various qcd
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Suppose that you have an abstract for a scientific paper: the germanium detector array ( ) experiment at the gran sasso underground laboratory ( lngs ) of infn is searching for neutrinoless double beta ( @xmath0 ) decay of @xmath1ge .
the signature of the signal is a monoenergetic peak at 2039 kev , the @xmath2 value of the decay . to avoid bias in the signal search
, the present analysis does not consider all those events , that fall in a 40 kev wide region centered around @xmath2 .
the main parameters needed for the @xmath0 analysis are described .
a background model was developed to describe the observed energy spectrum .
the model contains several contributions , that are expected on the basis of material screening or that are established by the observation of characteristic structures in the energy spectrum .
the model predicts a flat energy spectrum for the blinding window around @xmath2 with a background index ranging from 17.6 to 23.8@xmath3@xmath4 cts/(kev@xmath3kg@xmath3yr ) . a part of the data not considered before
has been used to test if the predictions of the background model are consistent .
the observed number of events in this energy region is consistent with the background model .
the background at @xmath2 is dominated by close sources , mainly due to @xmath5k , @xmath6bi , @xmath7th , @xmath8co and @xmath9 emitting isotopes from the @xmath10ra decay chain .
the individual fractions depend on the assumed locations of the contaminants .
it is shown , that after removal of the known @xmath11 peaks , the energy spectrum can be fitted in an energy range of 200 kev around @xmath2 with a constant background .
this gives a background index consistent with the full model and uncertainties of the same size .
example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave .4 setgray fill grestore stroke grestore .
And you have already written the first three sentences of the full article: some even - even nuclei are energetically forbidden to decay via single @xmath12 emission , while the decay via emission of two electrons and two neutrinos is energetically allowed .
the experimentally observed neutrino accompanied double beta ( @xmath13 ) decay is a second order weak process with half lives of the order of 10@xmath14 yr @xcite .
the decay process without neutrino emission , neutrinoless double beta ( @xmath0 ) decay , is of fundamental relevance as its observation would imply lepton number violation indicating physics beyond the standard model of particle physics ..
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the gerda experiment @xcite is designed to search for @xmath0 decay in the isotope @xmath1ge .
this process is identified by a monoenergetic line in the energy sum spectrum of the two electrons at 2039 kev @xcite , the @xmath2-value of the decay .
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Suppose that you have an abstract for a scientific paper: the possibility of using antihydrogen for igniting inertial confinement fusion pellets or triggering large - scale thermonuclear explosions is investigated .
the number of antiproton annihilations required to start a thermonuclear burn wave in either @xmath0 or @xmath1 is found to be about @xmath2 , where @xmath3 is the compression factor of the fuel to be ignited .
we conclude that the financial and energy investments needed to produce such amounts of antiprotons would confine applications of antimatter triggered thermonuclear devices to the military domain . .
And you have already written the first three sentences of the full article: matter - antimatter interaction produces more energy per unit mass than any other means of energy production . for example , proton - antiproton annihilation releases 275 times more energy in the form of kinetic energy of charged particles than nuclear fission or @xmath0 fusion .
this energy is released by simple contact of antimatter with matter so that , in principle , no ignition energy is required to start the reaction .
it is therefore not surprising that the concept of using antimatter as an energy source has been in scientific literature for decades @xcite ..
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other practical applications of antimatter are under consideration .
for example , antimatter propulsion systems @xcite , space based power generators @xcite , directed energy weapons @xcite , cancer therapy @xcite . finally , both edward teller @xcite and andrei sakharov @xcite
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Suppose that you have an abstract for a scientific paper: the effect of weak localization on spin relaxation in a two - dimensional system with a spin - split spectrum is considered .
it is shown that the spin relaxation slows down due to the interference of electron waves moving along closed paths in opposite directions . as a result
, the averaged electron spin decays at large times as @xmath0 .
it is found that the spin dynamics can be described by a boltzmann - type equation , in which the weak localization effects are taken into account as nonlocal - in - time corrections to the collision integral .
the corrections are expressed via a spin - dependent return probability .
the physical nature of the phenomenon is discussed and it is shown that the `` nonbackscattering '' contribution to the weak localization plays an essential role .
it is also demonstrated that the magnetic field , both transversal and longitudinal , suppresses the power tail in the spin polarization . .
And you have already written the first three sentences of the full article: the relaxation of non - equilibrium spin polarization is the central phenomenon in spin - dependent transport in semiconductor nanostructures .
@xcite one of the most efficient mechanisms of electron spin relaxation in iii - v semiconductors is the well - known dyakonov - perel mechanism @xcite based on the classical picture of angular diffusion of the spin vector in a random magnetic field .
the field originates from the momentum - dependent spin - orbit splitting of the conduction band in the crystals with zinc - blend structure ..
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@xcite while passing through the crystal , the electron is scattered by impurities and its momentum changes randomly with time . as a consequence , the effective magnetic field also changes randomly with a correlation time of the order of the momentum relaxation time @xmath1 .
the spin relaxation time @xmath2 is a characteristic time of the spin angular diffusion @xcite @xmath3 , where @xmath4 is the typical angle of the spin precession for the momentum relaxation time and @xmath5 is the frequency of precession in the effective magnetic field proportional to the conduction band splitting .
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12,391 |
Suppose that you have an abstract for a scientific paper: in this paper we explore the spin - orbit - induced bound state and molecular signature of the degenerate fermi gas in a narrow feshbach resonance based on a generalized two - channel model . without the atom - atom interactions ,
only one bound state can be found even if spin - orbit coupling exists .
moreover , the corresponding bound - state energy depends strongly on the strength of spin - orbit coupling , but is influenced slightly by its type .
in addition , we find that when increasing the strength of spin - orbit coupling , the critical point at which the molecular fraction vanishes shifts from zero to the negative detuning . in the weak spin - orbit coupling ,
this shifting is proportional to the square of its strength .
finally , we also show that the molecular fraction can be well controlled by spin - orbit coupling . .
And you have already written the first three sentences of the full article: recently , the investigation of spin - orbit ( so ) coupling in neutral atoms has attracted much attentions @xcite . in particular , a one - dimensional ( 1d ) equal rashba and dresselhaus so coupling has been first realized in the ultracold @xmath0rb atoms by a couple of raman lasers @xcite . by applying the same laser technique , this 1d so
coupling has been also achieved experimentally in the degenerate fermi gas with @xmath1k @xcite and @xmath2li @xcite .
theoretical investigations have been revealed that in the presence of so coupling , the degenerate fermi gas can exhibit the interesting physics in both three jpv , gm , yzq , hh , jpv1,iskin , lj , wy1,ld , li , ks , kz , rl , zhangp1,peng1,hly1,ld1 and lower dimensions @xcite ..
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for example , by increasing the strength of so coupling , the density of state at the fermi surface is increased , and the cooper paring gap can be thus enhanced significantly @xcite .
more importantly , this system may be changed from the bardeen - cooper - schrieffer ( bcs ) superfluid to the bose - einstein condensate ( bec ) with a new two - body bound state called rashbon @xcite . when an effective zeeman field is applied , the 2d degenerate fermi gas with the rashba so coupling exhibits an exotic topological superfluid supporting the majorana fermions @xcite , which is the heart for realizing the topological quantum computing @xcite .
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Suppose that you have an abstract for a scientific paper: the magnetic properties of a quasi two - dimensional superconductor , sn - metal graphite ( mg ) , are studied using dc and ac magnetic susceptibility .
sn - mg has a unique layered structure where sn metal layer is sandwiched between adjacent graphene sheets .
this compound undergoes a superconducting transition at @xmath0 = 3.75 k at @xmath1 = 0 .
the @xmath1-@xmath2 diagram of sn - mg is similar to that of a quasi two - dimensional superconductors .
the phase boundaries of vortex liquid , vortex glass , and vortex lattice phase merge into a multicritical point located at @xmath3 = 3.4 k and @xmath4 = 40 oe . there are two irreversibility lines denoted by @xmath5 ( de almeida - thouless type ) and @xmath6 ( gabay - toulouse type ) , intersecting at @xmath7= 2.5 k and @xmath8 = 160 oe .
the nature of slow dynamic and nonlinearity of the vortex glass phase is studied .
vortex glass phase , phase diagram , magnetic irreversibility 74.25.ha , 74.25.dw , 74.60.ec , 74.80.dm .
And you have already written the first three sentences of the full article: the existence of vortex glass phase in the mixed state of quasi two - dimensional ( 2d ) high-@xmath0 superconductors such as yba@xmath9cu@xmath10o@xmath11 in the presence of magnetic field ( @xmath1 ) attracts considerable attention @xcite .
mller et al .
@xcite have pointed out for the first time the existence of the glassy phase in la@xmath9cuo@xmath12:ba ..
Please generate the next two sentences of the article
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they have shown that the boundary between the vortex liquid phase and the vortex glass phase corresponds to the de almeida - thouless ( at ) @xcite line for the spin glass behavior . since
then there have been a number of experimental works on the vortex glass phase in quasi 2d superconductors .
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Suppose that you have an abstract for a scientific paper: we consider nanojunctions in the single - electron tunnelling regime which , due to a high degree of spatial symmetry , have a degenerate many body spectrum . as a consequence ,
interference phenomena which cause a current blocking can occur at specific values of the bias and gate voltage .
we present here a general formalism to give necessary and sufficient conditions for interference blockade also in the presence of spin polarized leads . as an example we analyze a triple quantum dot single electron transistor ( set ) . for a set - up with parallel polarized leads ,
we show how to selectively prepare the system in each of the three states of an excited spin triplet without application of any external magnetic field . .
And you have already written the first three sentences of the full article: single particle interference is one of the most genuine quantum mechanical effects . since the original double - slit experiment @xcite
, it has been observed with electrons in vacuum @xcite and even with the more massive @xmath0 molecules @xcite .
mesoscopic rings threaded by a magnetic flux provided the solid - state analogous @xcite ..
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intra - molecular interference has been recently discussed in molecular junctions for the case of strong @xcite and weak @xcite molecule - lead coupling . what unifies these realizations of quantum interference is that the travelling particle has two ( or more ) _ spatially equivalent _ paths at disposal to go from one point to another of the interferometer .
interference , though is hindered by decoherence .
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Suppose that you have an abstract for a scientific paper: cubic heterostructured ( * ba * ) particles of prussian blue analogues , composed of a shell of ferromagnetic k@xmath0ni[cr(cn)@xmath1@xmath2h@xmath3o ( * a * ) , @xmath4 k , surrounding a bulk core of photoactive ferrimagnetic rb@xmath5co[fe(cn)@xmath1@xmath6h@xmath3o ( * b * ) , @xmath7 k , have been studied . below @xmath4 k , these samples exhibit a persistent photoinduced decrease in low - field magnetization , and these results resemble data from other core - shell particles and analogous * aba * heterostructured films .
this net decrease suggests that the photoinduced lattice expansion in the * b * layer generates a strain - induced decrease in the magnetization of the * a * layer , similar to a pressure - induced decrease observed by others in a pure * a*-like material and by us in our * ba * cubes . upon further examination
, the data also reveal a significant portion of the * a * material whose superexchange , @xmath8 , is perturbed by the photoinduced strain from the * b * constituent . .
And you have already written the first three sentences of the full article: molecule - based magnets present an intriguing field of materials due to their combination of magnetism with various other physical phenomena .
specifically , those materials which exhibit photomagnetic properties provide a vast potential for technological applications . in recent years , prussian blue analogues ( pbas )
have piqued the interest of the molecular magnetism community due to their range of magnetic properties ..
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although examples exist that are known to order magnetically at or above room temperature @xcite , the feature that distinguishes a particularly appealing subset of pbas is the phenomenon of a charge - transfer - induced spin transition ( ctist ) @xcite , which is linked with that of persistent photoinduced magnetism ( ppim ) @xcite . when these properties are combined with long - range magnetic order , the potential for information storage applications begins to emerge .
a quintessential example of such a material is the cofe - pba , a@xmath9co[fe(cn)@xmath1@xmath10h@xmath3o , where a is a monovalent alkali cation .
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Suppose that you have an abstract for a scientific paper: we prove a sufficient condition for frame - type wavelet series in @xmath0 , the hardy space @xmath1 , and @xmath2 .
for example , functions in these spaces are shown to have expansions in terms of the mexican hat wavelet , thus giving a strong answer to an old question of meyer .
bijectivity of the wavelet frame operator acting on hardy space is established with the help of new frequency - domain estimates on the caldern zygmund constants of the frame kernel . .
And you have already written the first three sentences of the full article: one of the first wavelets ever considered was the mexican hat ( see figure [ mexican ] ) , which is @xmath3 the mexican hat function @xmath4 , and its fourier transform @xmath5 . ]
the mexican hat function @xmath4 , and its fourier transform @xmath5 . ]
morlet @xcite generated the mexican hat system @xmath6 and applied it to geophysical problems as if it were orthonormal ( which it is not ) ..
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daubechies @xcite explained why morlet s approach succeeded : the system is an almost - tight _ frame _ , with its frame operator @xmath7 being a bijection on @xmath8 , and indeed being rather close to the identity . in other words ,
analysis followed by synthesis with the mexican hat system provides almost - perfect reconstruction in @xmath8 .
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Suppose that you have an abstract for a scientific paper: the dependence of wakefield amplitude and phase on beam and plasma parameters is studied in the parameter area of interest for self - modulating proton beam - driven plasma wakefield acceleration .
the wakefield sensitivity to small parameter variations reveals the expected level of shot - to - shot jitter of experimental results .
of all the parameters , the plasma density stands out , as the wakefield phase is extremely sensitive to this parameter .
the study of large variations determines the effects that limit the achievable accelerating field in different parts of the parameter space : nonlinear elongation of the wakefield period , insufficient charge of the drive beam , emittance - driven beam divergence , and motion of plasma ions . .
And you have already written the first three sentences of the full article: the concept of proton driven plasma wakefield acceleration emerged five years ago @xcite .
the main motivation for using protons is that the energy content of state - of - the - art proton beams is sufficiently high to bring a substantial amount of electrons to tev energy scale in a single plasma section .
since plasmas can support extremely strong accelerating fields @xcite , this concept may open a path to the future of high - energy particle physics @xcite . in the initial proposal @xcite ,.
Please generate the next two sentences of the article
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the proton beam was assumed to be longitudinally compressed to the sub - millimeter length . that was necessary for driving the plasma wave with the wavelength of 1 mm or shorter .
however , as available proton beams have lengths of about 10 cm , such strong compression seems unrealistic to obtain with conventional techniques @xcite .
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Suppose that you have an abstract for a scientific paper: the results of 3d modelling of the flow structure in the classical symbiotic system z andromedae are presented .
outbursts in systems of this type occur when the accretion rate exceeds the upper limit of the steady burning range .
therefore , in order to realize the transition from a quiescent to an active state it is necessary to find a mechanism able to sufficiently increase the accretion rate on a time scale typical to the duration of outburst development .
our calculations have confirmed the transition mechanism from quiescence to outburst in classic symbiotic systems suggested earlier on the basis of 2d calculations ( bisikalo et al , 2002 ) .
the analysis of our results have shown that for wind velocity of 20 km / s an accretion disc forms in the system .
the accretion rate for the solution with the disc is @xmath0 of the mass loss rate of the donor , that is , @xmath1 @xmath2/yr for z and .
this value is in agreement with the steady burning range for white dwarf masses typically accepted for this system .
when the wind velocity increases from 20 to 30 km / s the accretion disc is destroyed and the matter of the disc falls onto the accretor s surface .
this process is followed by an approximately twofold accretion rate jump .
the resulting accretion rate growth is sufficient for passing the upper limit of the steady burning range , thereby bringing the system into an active state .
the time during which the accretion rate is above the steady burning value is in a very good agreement with observations .
the analysis of the results presented here allows us to conclude that small variations in the donor s wind velocity can lead to the transition from the disc accretion to the wind accretion and , as a consequence , to the transition from quiescent to active state in classic symbiotic stars . .
And you have already written the first three sentences of the full article: symbiotic stars are characterized by peculiar spectra where molecular absorption bands - the characteristic features of a cool giant - are present together with emission lines corresponding to a high excitation level .
the red and infrared spectra of symbiotic stars are typical of cool giants while in the uv range they are characterized by a very hot continuum .
it is widely assumed that most symbiotic stars are detached binaries consisting of a cool giant and a white dwarf surrounded by a nebulosity [ [ boyar67 ] ] ..
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mass exchange in these systems is driven by stellar wind .
the goal of this work is to carry out a study of classical symbiotic systems using as example one of the most well - studied representatives of this class - z and . according to the analyses of its energy distribution in a wide spectral range [ [ fc88 ] ] , the components of z and have the following characteristics : the cool m3.5iii giant has a mass @xmath3 and a radius @xmath4 100@xmath5 , while the white dwarf has a mass @xmath6 , a radius @xmath4 0.07@xmath5 and a temperature @xmath7 k. the giant loses mass at the rate of @xmath8/yr .
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Suppose that you have an abstract for a scientific paper: in this paper , we consider homology groups induced by the exterior algebra generated by a simplicial compliment of a simplicial complex @xmath0 .
these homology groups are isomorphic to the tor - groups @xmath1}({\mathbf{k}}(k),{\mathbf{k}})$ ] of the face ring @xmath2 , which is very useful and much studied in toric topology . by using ech homology theory and alexander duality theorem , we prove that these homology groups have dualities with the simplicial cohomology groups of the full subcomplexes of @xmath0 .
then we give a new proof of hochster s theorem . .
And you have already written the first three sentences of the full article: throughout this paper , @xmath3 is a field or the ring of integers @xmath4 .
@xmath5={\mathbf{k}}[v_1,\dots , v_m]$ ] is the graded polynomial algebra on @xmath6 variables , deg@xmath7 .
the _ face ring _.
Please generate the next two sentences of the article
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( also known as the _ stanley - reisner ring _ ) of a simplicial complex @xmath0 with @xmath6 vertices is the quotient ring @xmath8/\mathcal { i}_k\ ] ] where @xmath9 is the ideal generated by those square free monomials @xmath10 for which @xmath11 is not a simplex in @xmath0 . for any simple polytope @xmath12 , davis and januszkiewicz @xcite introduced a @xmath13-manifold @xmath14 with orbit space @xmath12 .
after that buchstaber and panov @xcite generalized this definition to any simplicial complex @xmath0 with vertex set @xmath15=\{1,2,\dots , m\}$ ] , and named it the _ moment - angle complex _ associated to @xmath0 : @xmath16 where @xmath17 , @xmath18 if @xmath19 and @xmath20 if @xmath21 .
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12,399 |
Suppose that you have an abstract for a scientific paper: we use the representation theory of @xmath0 superconformal algebra to study the elliptic genera of calabi yau ( cy ) @xmath1-folds .
we compute the entropy of cy manifolds from the growth rate of multiplicities of the massive ( non - bps ) representations in the decomposition of their elliptic genera .
we find that the entropy of cy manifolds of complex dimension @xmath1 behaves differently depending on whether @xmath1 is even or odd .
when @xmath1 is odd , cy entropy coincides with the entropy of the corresponding hyperkhler @xmath2-folds due to a structural theorem on jacobi forms . in particular
, we find that the calabi
yau @xmath3-fold has a vanishing entropy . at @xmath4 , using our previous results on hyperkhler manifolds , we find @xmath5 .
when @xmath1 is even , we find the behavior of cy entropy behaving as @xmath6 .
these agree with cardy s formula at large @xmath1 .
yitp report 10 - 14 .
And you have already written the first three sentences of the full article: the @xmath0 superconformal algebra ( sca ) is a basic tool in the world - sheet analysis of string compactifications on calabi yau ( cy ) manifold with complex dimension-@xmath1 .
it is well - known that in @xmath0 sca there exist two types of representations : bps ( massless ) and non - bps ( massive ) representations .
bps representations appear when the conformal weight @xmath7 of their highest - weight state hits the unitarity bound @xmath8 ( in the ramond sector ) where @xmath9 denotes the central charge of sca . on the other hand.
Please generate the next two sentences of the article
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non - bps representations appear at @xmath10 .
we study the decomposition of the elliptic genus for calabi
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