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Suppose that you have an abstract for a scientific paper: rectification of microwave radiation ( 20 - 40 ghz ) by a line boundary between two two - dimensional metals on a silicon surface was observed and investigated at different temperatures , in - plane magnetic fields and microwave powers .
the rectified voltage @xmath0 is generated whenever the electron densities @xmath1 of the two metals are different , changing polarity at @xmath2 .
very strong nonlinear response is found when one of the two 2d metals is close to the electron density corresponding to the reported magnetic instability in this system .
-0.5 cm 2 .
And you have already written the first three sentences of the full article: dilute low dimensional systems have been the focus of a great deal of recent attention due to their interesting physical properties at low temperature@xcite .
a number of fascinating phenomena have been reported for low - density electron systems in high mobility silicon inversion layers as a function of magnetic field . a dramatic increase of the resistivity in response to in - plane magnetic field
has been shown to be associated at high electron density with complete spin polarization of the carriers @xcite ..
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a number of experiments have recently shown that the spin susceptibility increases substantially as the density is decreased @xcite , indicating a possible divergence and ferromagnetic instability at finite electron density . through a detailed study of the magnetoconductivity as a function of temperature and electron density ,
we have identified an energy scale @xmath3 associated with the response of the electrons to a magnetic field applied parallel to the plane of the electrons @xcite .
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10,301 |
Suppose that you have an abstract for a scientific paper: we consider exclusive @xmath0 production in ep - scattering . at high energies odderon and photon
exchange contribute .
the photon exchange contribution is evaluated exactly using data for the total virtual photon - proton absorption cross section .
the odderon exchange contribution is calculated in nonperturbative qcd , using functional integral techniques and the model of the stochastic vacuum . for the proton we assume a quark - diquark structure as suggested by the small odderon amplitude in @xmath1 and @xmath2 forward scattering .
we show that odderon exchange leads to a much larger inelastic than elastic @xmath0 production cross section . observing our process at hera
would establish the soft odderon . .
And you have already written the first three sentences of the full article: the soft ( nonperturbative ) odderon @xmath3 is introduced in elastic hadron - hadron scattering as the @xmath4 partner of the pomeron @xmath5 @xcite . in perturbation theory
the existence of @xmath4 contributions is clear ( 3-gluon exchange ) .
it is even believed @xcite , that 3-gluon exchange dominates the @xmath6-scattering amplitude @xmath7 for momentum transfers @xmath8 . on the other hand , for @xmath9.
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it seems that odderon contributions play no role asymptotically or even are absent .
an example is the measurement of @xmath10 at @xmath11 gev @xcite .
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10,302 |
Suppose that you have an abstract for a scientific paper: cells actively probe and respond to the stiffness of their surroundings . since mechanosensory cells in connective tissue are surrounded by a disordered network of biopolymers , their _ in vivo _ mechanical environment can be extremely heterogeneous . here , we investigate how this heterogeneity impacts mechanosensing by modeling the cell as an idealized local stiffness sensor inside a disordered fiber network . for all types of networks
we study , including experimentally - imaged collagen and fibrin architectures , we find that measurements applied at different points throughout a given network yield a strikingly broad range of local stiffnesses , spanning roughly two decades .
we verify via simulations and scaling arguments that this broad range of local stiffnesses is a generic property of disordered fiber networks , and show that the range can be further increased by tuning specific network features , including the presence of long fibers and the proximity to elastic transitions .
these features additionally allow for a highly tunable dependence of stiffness on probe length . finally , we show that to obtain optimal , reliable estimates of global tissue stiffness , a cell must adjust its size , shape , and position to integrate multiple stiffness measurements over extended regions of space .
mechanical cues can govern cellular behavior in decisive ways ( 1 - 2 ) .
the elastic properties of a cell s substrate have been shown to guide cell migration ( 3 , 4 ) and determine cell fate ( 5 , 6 ) .
eukaryotic cells , including fibroblasts , mesenchymal stem cells , and cancer cells , attach to substrates via transmembrane protein complexes called focal adhesions , allowing the cell to sense stiffness ( 2 , 7 - 10 ) .
knockdown studies have established that this mechanosensing contributes both to motility and to the regulation of cell shape in three - dimensional _ in vitro
_ systems that closely resemble _ in vivo _ cellular environments ( 10 - 13 ) , where cells are surrounded by a loosely....
And you have already written the first three sentences of the full article: cells in connective tissue can glean mechanical information about their surroundings by pulling on the individual biopolymers of the ecm .
however , on the short length scale of a typical cell , the measured mechanical response is sensitive to the intrinsic structural disorder of the ecm . to investigate the role of local mechanical disorder in a physiologically relevant system , we considered collagen networks , which form the primary structural component of the ecm ( 14 ) .
we prepared a sample network by reconstituting fluorescently - labeled collagen type - i monomers and imaged its three - dimensional structure ( 31 , _ supporting information _ ) . the network is loosely connected ( with an average coordination number @xmath0 ) and highly heterogeneous at the cellular scale ( with an average mesh size @xmath1 m ) ..
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this reconstituted collagen architecture was used as an input to construct a mechanical network model where the fibers are treated as elastic beams that can bend and stretch ( fig .
1__a _ _ ) . for simplicity , we modeled the stretching and bending of the beams , respectively , as springs and torsional springs connecting point - like vertices with stretching modulus @xmath2 and bending modulus @xmath3 .
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10,303 |
Suppose that you have an abstract for a scientific paper: analysis is performed on ultra - high resolution large - scale cosmological radiation - hydrodynamic simulations to , for the first time , quantify the physical environment of long - duration gamma - ray bursts ( grbs ) at the epoch of reionization .
we find that , on parsec scales , 13% of grbs remain in high density ( @xmath0@xmath1 ) low - temperature star - forming regions , whereas 87% of grbs occur in low - density ( @xmath2@xmath1 ) high temperature regions heated by supernovae .
more importantly , the spectral properties of grb afterglows , such as the neutral hydrogen column density , total hydrogen column density , dust column density , gas temperature and metallicity of intervening absorbers , vary strongly from sightline to sightline . although our model explains extant limited observationally inferred values with respect to circumburst density , metallicity , column density and dust properties , a substantially larger sample of high - z grb afterglows would be required to facilitate a statistically solid test of the model .
our findings indicate that any attempt to infer the physical properties ( such as metallicity ) of the interstellar medium of the host galaxy based on a very small number of ( usually one ) sightlines would be precarious . utilizing high - z grbs to probe interstellar medium and intergalactic medium should be undertaken properly taking into consideration the physical diversities of the interstellar medium .
= 1 .
And you have already written the first three sentences of the full article: very high redshift ( @xmath3 ) gamma - ray bursts ( grbs ) ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
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* ) provide an excellent probe of both the interstellar ( ism ) and intergalactic medium ( igm ) at the epoch of reionization ( eor ) using absorption spectrum techniques thanks to their simple power - law afterglow spectra and high luminosity @xcite , complimentary to quasar absorption spectrum observations @xcite . here
we present a first , detailed analysis of the physical properties of ism surrounding grbs , utilizing state - of - the - art radiation - hydrodynamic simulations , with the hope that they may aid in proper interpretations of observations of grb afterglows at eor with respect to both ism and igm .
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10,304 |
Suppose that you have an abstract for a scientific paper: since their invention , polar codes have received a lot of attention because of their capacity - achieving performance and low encoding and decoding complexity . successive cancellation decoding ( scd ) and belief propagation decoding ( bpd ) are two approaches for decoding polar codes .
scd is able to achieve good error - correcting performance and is less computationally expensive as compared to bpd .
however scd suffers from long latency due to the serial nature of the successive cancellation algorithm .
bpd is parallel in nature and hence is more attractive for low latency applications .
however , since it is iterative , the required latency and energy dissipation increases linearly with the number of iterations . in this work
, we borrow the idea of scd and propose a novel scheme based on sub - factor - graph freezing to reduce the average number of computations as well as the average number of iterations required by bpd , which directly translates into lower latency and energy dissipation .
simulation results show that the proposed scheme has no performance degradation and achieves significant reduction in computation complexity over the existing methods .
= 1 belief propagation decoding ( bpd ) ; successive cancellation decoding ( scd ) ; energy efficiency ; iterative decoders ; factor graph ; polar codes .
And you have already written the first three sentences of the full article: shanon proved existence of maximum data transmission rate , called channel capacity @xcite . since then
, different capacity - approaching codes have been designed , like turbo codes @xcite and ldpc codes @xcite .
the first provable capacity - achieving codes , polar codes , were recently invented by arikan @xcite ..
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polar codes are considered to be a major breakthrough in coding theory , since they are the first family of codes known to achieve channel capacity with explicit construction . besides achieving the capacity for binary - input symmetric memoryless channels @xcite
, polar codes were also proved in @xcite to be able to achieve the capacity for any discrete and continuous memoryless channel . moreover ,
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10,305 |
Suppose that you have an abstract for a scientific paper: the liquid droplet formula is applied to an analysis of the properties of geometrical ( anti)clusters formed in su(2 ) gluodynamics by the polyakov loops of the same sign . using this approach
, we explain the phase transition in su(2 ) gluodynamics as a transition between two liquids during which one of the liquid droplets ( the largest cluster of a certain polyakov loop sign ) experiences a condensation , while the droplet of another liquid ( the next to the largest cluster of the opposite sign of polyakov loop ) evaporates .
the clusters of smaller sizes form two accompanying gases , which behave oppositely to their liquids .
the liquid droplet formula is used to analyze the size distributions of the gaseous ( anti)clusters .
the fit of these distributions allows us to extract the temperature dependence of surface tension and the value of fisher topological exponent @xmath0 for both kinds of gaseous clusters .
it is shown that the surface tension coefficient of gaseous ( anti)clusters can serve as an order parameter of the deconfinement phase transition in su(2 ) gluodynamics .
the fisher topological exponent @xmath0 of clusters and anticlusters is found to have the same value 1.806 @xmath1 0.008 .
this value disagrees with the famous fisher droplet model , but it agrees well with an exactly solvable model of the nuclear liquid - gas phase transition .
this finding may evidence for the fact that the su(2 ) gluodynamics and this exactly solvable model of nuclear liquid - gas phase transition are in the same universality class . .
And you have already written the first three sentences of the full article: the lattice simulations are presently considered as the only first principle tool to investigate the deconfinement phase transition ( pt ) in quantum chromodynamics ( qcd ) .
such a pt is also expected in gluodynamics ( gd ) which is a pure non - abelian gauge theory .
the svetitsky - jaffe hypothesis @xcite relates the deconfinement pt in ( d+1)-dimensional su(n ) gd to the magnetic pt in z(n ) symmetric spin model in d - dimensions ..
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the local polyakov loops in gd are playing the role of spins in z(n ) symmetric spin model .
for the ( d+1)-dimensional lattice having the size @xmath2 the local polyakov loop is defined by the temporal gauge links @xmath3 as @xmath4 a high level of understanding of the spin systems along with the svetitsky - jaffe hypothesis led to a significant progress in studying the su(n ) gd properties in the pt vicinity .
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Suppose that you have an abstract for a scientific paper: we use a novel monte carlo method to study the mott transition in an anisotropic triangular lattice . the real space approach , retaining extended spatial correlations , allows an accurate treatment of non trivial magnetic fluctuations in this frustrated structure . choosing the degree of anisotropy to mimic the situation in the quasi - two dimensional organics , @xmath0(bedt - ttf)@xmath1cu[n(cn)@xmath1]-x
, we detect a wide pseudogap phase , with anomalous spectral and transport properties , between the ` ungapped ' metal and the ` hard gap ' mott insulator .
the magnetic fluctuations also lead to pronounced momentum dependence of quasiparticle damping and pseudogap formation on the fermi surface as the mott transition is approached .
our predictions about the ` bad metal ' state have a direct bearing on the organics where they can be tested via tunneling , angle resolved photoemission , and magnetic structure factor measurement .
the mott metal - insulator transition ( mit ) , and the proximity to a mott insulator in doped systems , are crucial issues in correlated electron systems @xcite .
the mott transition on a bipartite lattice is now well understood , but the presence of triangular motifs in the structure brings in geometric frustration @xcite .
this promotes incommensurate magnetic fluctuations whose nature , and impact on the mit , remain outstanding problems .
the organic salts provide a concrete testing ground for these effects @xcite .
the @xmath0(bedt - ttf)@xmath1cu[n(cn)@xmath1]-x salts are quasi two dimensional ( 2d ) materials where the bedt - ttf dimers define a triangular lattice with anisotropic hopping @xcite .
the large lattice spacing , @xmath3 , leads to a low bandwidth , enhancing electron correlation effects , while the triangular motif disfavours neel order .
the x@xmath4cl@xmath5br@xmath6 family shows a mit as @xmath7 drops below @xmath8 @xcite .
the metallic state is _ very incoherent _ above @xmath9k : the resistivity @xcite is large ,....
And you have already written the first three sentences of the full article: our starting point is the hubbard model @xmath165 we implement a rotation invariant decoupling of the hubbard interaction as follows .
first , one can write @xmath166 where @xmath167 is the charge density , @xmath168 is the local electron spin operator , and @xmath169 is an _
arbitrary unit vector_. the partition function of the hubbard model is @xmath170e^{-s } \cr s & = & \int_{0}^{\beta}d \tau { \cal l}(\tau ) \cr { \cal l } & = & \sum_{i\sigma } \bar{c}_{i\sigma}(\tau)\partial_{\tau}c_{i\sigma}(\tau ) + h(\tau ) \nonumber\end{aligned}\ ] ] we can introduce two space - time varying auxiliary fields for a hubbard - stratonovich transformation : ( i ) @xmath171 coupling to charge density , and ( ii ) @xmath172 coupling to electron spin density ( @xmath173 is real positive ) ..
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this allows us to define a su(2 ) invariant hs transformation ( see ref .
@xcite ) , @xmath174 the partition function now becomes : @xmath175 \nonumber\end{aligned}\ ] ] as discussed in the text , to make progress we need two approximations : ( i ) neglect the time ( @xmath176 ) dependence of the hs fields , ( ii ) replace the field @xmath39 by its saddle point value @xmath177 , since the important low energy fluctuations arise from the @xmath38 .
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10,307 |
Suppose that you have an abstract for a scientific paper: uvsipm is a light detector designed to measure the intensity of electromagnetic radiation in the 320900 nm wavelength range .
it has been developed in the framework of the astri project whose main goal is the design and construction of an end - to - end small size class telescope prototype for the cherenkov telescope array .
the uvsipm instrument is composed by a multipixel silicon photo - multiplier detector unit coupled to an electronic chain working in single photon counting mode with 10 nanosecond double pulse resolution , and by a disk emulator interface card for computer connection .
the detector unit of uvsipm is of the same kind as the ones forming the camera at the focal plane of the astri prototype .
eventually , the uvsipm instrument can be equipped with a collimator to regulate its angular aperture .
uvsipm , with its peculiar characteristics , will permit to perform several measurements both in lab and on field , allowing the absolute calibration of the astri prototype .
detector : sipm .
And you have already written the first three sentences of the full article: uvsipm is a stand - alone portable photon detector instrument designed to measure electromagnetic radiation in the 320900 nm wavelength range .
it has been developed in the framework of astri ( astrofisica con specchi a tecnologia replicante italiana ) project @xcite a `` flagship project '' financed by the italian ministry of education , university and research ( miur ) and led by the italian national institute of astrophysics ( inaf ) .
the astri project is focused , in its first phase , on the design and construction of an end - to - end small size scale telescope prototype for the cherenkov telescope array ( cta ) @xcite , the international next generation ground - based observatory for very high energy gamma - rays ( from a few tens of gev up to several hundred of tev ) ..
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the astri project will cover the highest part of the energy spectrum adopting innovative and challenging solutions never used in the framework of cherenkov telescopes : the optics system will be based on a double mirror in schwarzschild - couder configuration instead of the standard single mirror ; the camera will be composed by an array of monolithic multipixel silicon photo - multipliers ( sipm ) instead of the usual photo multiplier tubes ( pmt ) .
uvsipm , developed at iasf - palermo and based on the same sipm used for the astri prototype , has the aim of characterizing the device and evaluating its performance in lab ; the final goal is to use uvsipm as tool for the on field absolute calibration of the astri prototype .
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10,308 |
Suppose that you have an abstract for a scientific paper: the ground state of the @xmath0 antiferromagnetic heisenberg chain belongs to the haldane phase a well known example of symmetry - protected topological phase . a staggered field applied to the @xmath0 antiferromagnetic chain breaks all the symmetries that protect the haldane phase as a topological phase , reducing it to a trivial phase .
that is , the haldane phase is then connected adiabatically to an antiferromagnetic product state .
nevertheless , as long as the symmetry under site - centered inversion combined with a spin rotation is preserved , the phase is still distinct from another trivial phase .
we demonstrate the existence of such distinct symmetry - protected _ trivial _ phases using a field - theoretical approach and numerical calculations .
furthermore , a general proof and a non - local order parameter are given in terms of an matrix - product state formulation . _
_ introduction.__while symmetry broken phases can be completely classified using the landau theory , there still exists no exhaustive understanding of topological quantum phases .
topological quantum phases are gapped phases of matter that are distinct from trivially disordered states but can not be characterized by any local order parameter . over the past few years
, new theoretical frameworks have been developed to understand and classify many different topological phases .
for example , topological phases of noninteracting fermions are now completely classified using k - theory @xcite .
more generally , two gapped ground states belong to the same phase if and only if they can adiabatically connected with respect to local hamiltonians @xcite .
even when different states are connected by a general adiabatic process , it is possible that they can no longer be adiabatically connected if we impose symmetries on the hamiltonian .
these are either states with spontaneous symmetry breaking or belong to the class of symmetry - protected topological ( spt ) phase @xcite .
examples of spt phases include....
And you have already written the first three sentences of the full article: in this supplemental material , we present several numerical details about the spin-1 chain , @xmath126 .
\end{aligned}\ ] ] for @xmath63 and @xmath127 , from the divergent behavior of the correlation length in fig.1(a ) of the main text , we expect a gaussian transition at @xmath72 . to confirm this , we calculate the von neumann entanglement entropy @xmath128 for a bipartition of the system into two half chains as a function of the correlation length @xmath129 . from conformal field theory ,
the entanglement entropy is known to scale as @xcite @xmath130 where @xmath131 is the central charge , @xmath132 is the lattice spacing ( we set @xmath133 ) , and @xmath134 is a nonuniversal constant . as shown in fig ..
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[ fig : eeandmx ] ( a ) , the entanglement entropy @xmath128 at @xmath135 is well fitted by a linear function of @xmath136 , and the central charge is estimated as @xmath137 .
this is close to the expected value @xmath138 at the gaussian transition . for @xmath65 and @xmath139 ,
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10,309 |
Suppose that you have an abstract for a scientific paper: we study light propagation in a neutral weyl semimetal with the fermi level lying at the weyl nodes in the weak self - interacting regime .
the nontrivial topology induces a screening effect in one of the two transverse gauge fields , for which we find two branches of attenuated collective excitations .
in addition to the known topologically gaped photon mode , a novel massless and slightly damped excitation appears .
strikingly , at low energies this new excitation has a linear dispersion and it propagates with the same velocity than the electrons , while at energies well above the electron - hole continuum threshold it behaves as a massive attenuated photon with velocity similar to the speed of light in the material .
there is a crossover at certain momentum in the direction perpendicular to the separation of the weyl nodes above which the novel gapless mode enters into an overdamped regime .
regarding the unscreened gauge field we show that it is also attenuated , which is a non - topological property shared by dirac semimetals as well . .
And you have already written the first three sentences of the full article: weyl semimetals ( wsm ) are three dimensional topological electronic systems whose low energy band structure is described by pairs of weyl fermions separated in momentum space .
they were first proposed to occur in a class of iridate materials@xcite , but it was only recently that they were experimentally realized@xcite .
the topological properties of wsms are encoded in a chern - simons ( cs ) term that stems from the axial anomaly ..
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the anomaly is responsible of a plethora of phenomena like the axial magnetic effect@xcite , chiral separation effect@xcite , chiral magnetic waves@xcite and , more recently , a new mechanism for the phonon hall viscosity@xcite . the experimental evidence of the wsm phase is based on arpes and transport experiments@xcite , and on optical conductivity experiments@xcite (
optical measurements have been done in dirac semimetals as well@xcite ) .
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Suppose that you have an abstract for a scientific paper: using hydrodynamical numerical simulations we show that high - velocity ejecta with @xmath0 in the outbursts of the supernova impostor sn 2009ip and similar luminous blue variable ( lbv ) stars can be explained by the interaction of fast jets , having @xmath1 , with a circumbinary shell ( extended envelope ) .
the density profile in the shell is very steep such that the shock wave , that is excited by the jets interaction with the shell , accelerates to high velocities as it propagates outward .
the amount of very fast ejecta is small , but sufficient to account for some absorption lines .
such an extended envelope can be formed from the binary interaction and/or the unstable phase of the lbv primary star .
the jets themselves are launched by the more compact secondary star near periastron passages . .
And you have already written the first three sentences of the full article: the sn impostor sn 2009ip is an lbv star @xcite that experienced a series of outbursts starting in 2009 ( e.g. , @xcite ) .
there were two outbursts in 2012 : the 2012a outburst that was similar to the previous outbursts , and the 2012b outburst in september 2012 that was much more energetic than the previous outbursts ( e.g. , @xcite ) .
there is no consensus on the nature of the 2012a and 2012b outbursts ( e.g. @xcite ) , and not even on whether the lbv primary star survived the 2012 outbursts or exploded as a core collapse supernova ( ccsn ) ..
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the peak luminosity of the 2012b outburst and the p - cygni absorption wings that extend to @xmath2 brought @xcite to suggest that the 2012a outburst was a weak sn event , while the major 2012b outburst is a result of the collision of the sn ejecta with previously ejected gas ( also @xcite ) .
however , @xcite noted that the photosphere expansion velocity of @xmath3 during the 2012b outburst implies that the gas that accelerated the photosphere must have originated long after the peak of the 2012a event .
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Suppose that you have an abstract for a scientific paper: we study the renormalization group ( rg ) evolution of the couplings in a model with a real su(2 ) triplet in the higgs sector . insisting that the model remain valid up to 1 tev we show that it is possible for there to be no light higgs bosons without any otherwise dramatic deviation from the physics of the standard model . .
And you have already written the first three sentences of the full article: in this contribution we extend the study in ref .
@xcite of an extension of the standard model in which a real scalar @xmath0 triplet with zero hypercharge is added to the usual scalar @xmath0 doublet . for details
the scalar potential of the model in terms of the usual standard model higgs , @xmath1 , and the new triplet , @xmath2 , reads @xmath3 where @xmath4 are the pauli matrices ..
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the expansion of the field components is @xmath5 with @xmath6 and @xmath7 is the goldstone boson which is eaten by the @xmath8 .
the model violates custodial symmetry at tree level giving a prediction of @xmath9 for the @xmath10-parameter . in the neutral higgs sector
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Suppose that you have an abstract for a scientific paper: a two species reaction - diffusion model , in which particles diffuse on a one - dimensional lattice and annihilate when meeting each other , has been investigated .
mean field equations for general choice of reaction rates have been solved exactly .
cluster mean field approximation of the model is also studied .
it is shown that , the general form of large time behavior of one- and two - point functions of the number operators , are determined by the diffusion rates of the two type of species , and is independent of annihilation rates .
* cluster approximation solution of a two species annihilation model * 2 cm f. tabatabaee@xmath0 , a. aghamohammadi@xmath1 5 mm _ @xmath2 department of physics , alzahra university , tehran 19834 , iran .
_ _ @xmath3 institute for applied physics , tehran 15857 - 5878 iran . _
* pacs numbers : * * keywords : * reaction - diffusion , cluster mean field .
And you have already written the first three sentences of the full article: recently properties of systems far from equilibrium have been studied by many people .
although mean field techniques may give qualitatively correct results for higher dimensions , for low - dimensional systems fluctuations have important roles .
different methods have been used to study reaction - diffusion models , including analytical and approximational methods . among them.
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, there are methods to obtain some quantities can be obtained exactly .
for example in @xcite , imposing some constraints on the reaction rates leads to a closed set of equations for average number densities in each site .
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Suppose that you have an abstract for a scientific paper: recent observations have shown that the direct - impact algol systems u crb and rs vul possess gas located outside of the orbital plane , including a tilted accretion disc in u crb .
observations of circumstellar gas surrounding the mass donor in rs vul suggest magnetic effects could be responsible for deflecting the accretion stream out of the orbital plane , resulting in a tilted disc .
to determine whether a tilted disc is possible due to a deflected stream , we use three - dimensional hydrodynamic simulations of the mass transfer process in rs vul . by deflecting the stream @xmath0 out of the orbital plane and boosting the magnitude of the stream s velocity to mach 30 , we mimic the effects of magnetic activity near l1 .
we find that the modified stream parameters change the direct - impact nature of the system .
the stream misses the surface of the star , and a slightly warped accretion disc forms with no more than @xmath1 of disc tilt .
the stream - disc interaction for the deflected stream forces a large degree of material above the orbital plane , increasing the out - of - plane flow drastically . plotting the h@xmath2 emissivity in velocity space allows us to compare our results with tomographic observations . deflecting and boosting the stream increases the emissivity in each @xmath3 slice of the out - of - plane flow by at least three and up to eight orders of magnitude compared to the undeflected case .
we conclude that a deflected stream is a viable mechanism for producing the strong out - of - plane flows seen in the tomographic images of u crb and rs vul .
accretion , accretion discs hydrodynamics stars : binaries : close .
And you have already written the first three sentences of the full article: the recent use of three - dimensional doppler tomography to investigate the algol binaries u crb and rs vul has unveiled a significant amount of detail regarding the accretion process in these systems . as well as confirming the presence of a number of features seen in two - dimensional tomographic data , the new data have shown an unexpectedly large amount of gas located outside of the orbital plane in both systems .
u crb also displays a transient accretion disc inclined with respect to the orbital plane , which is not expected if mass transfer occurs as a result of gravitational and centrifugal forces alone .
the companions in short - period algols are rapidly rotating late - type stars that are likely to be magnetically active ..
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magnetic behavior occuring at or near the first lagrange point ( l1 ) may offer an explanation for the out - of - plane material .
the notion that large - scale magnetic effects may drastically influence the morphology and time - evolution of the accretion processes is evidenced by the observations of @xcite , who noted the similarity in the out - of - plane velocities located at l1 and magnetically active regions on the donor star in rs vul .
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Suppose that you have an abstract for a scientific paper: we consider the spectra of excitations around diagonal and intersecting d - brane configurations on tori .
these configurations are described by constant curvature connections in a dual gauge theory description .
the low - energy string fluctuation spectrum is reproduced exactly by the gauge theory in the case of vanishing field strength ; however , this correspondence breaks down for fixed nonzero field strength .
we show that in many cases the full born - infeld action correctly captures the low - energy spectrum in the case of non - vanishing field strength .
this gives a field theory description of the low - energy physics of systems of diagonally wound branes and branes at angles as considered by berkooz , douglas and leigh .
this description extends naturally to non - supersymmetric configurations , where the tachyonic instability associated with brane - anti - brane systems appears as an instability around a saddle point solution of the corresponding yang - mills / born - infeld theory . in some cases
, the field theory description requires a non - abelian generalization of the born - infeld action .
we follow tseytlin s recent proposal for formulating such an action . in the case of intersecting branes ,
the non - abelian born - infeld theory produces a transcendental relation which comes tantalizingly close to reproducing the correct spectrum ; however , a discrepancy remains which indicates that a further clarification of the non - abelian born - infeld action may be necessary .
= msbm10 at 12pt = msbm7 = msbm5 = = = # 1#1 = 6.5 in pupt-1693 + hep - th/9703217 * fluctuation spectra of tilted and intersecting d - branes from the born - infeld action * akikazu hashimoto and washington taylor iv _ department of physics _ + _ joseph henry laboratories _ + _ princeton university _ + _ princeton , new jersey 08544 , u.s.a . _
+ aki , wati @princeton.edu march 1997 .
And you have already written the first three sentences of the full article: d - branes @xcite have recently emerged as a key ingredient driving the non - perturbative dynamics of string theory .
these objects provide an exact description of string theory solitons , and have led to remarkable developments towards understanding the nature of stringy black holes @xcite .
d - branes also provide a fascinating connection between string theory and gauge theories ..
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the low - energy effective dynamics of @xmath0 parallel d - branes is precisely that of supersymmetric yang - mills theory with gauge group @xmath1 @xcite ; such a low - energy effective theory has in turn been conjectured to provide a reformulation of string theory itself @xcite .
the goal of this paper is to extend further the range of phenomena in d - brane physics which can be described precisely in the language of yang - mills field theory or its extension to born - infeld theory . in particular , we consider the correspondence between the perturbative fluctuation spectra of d - brane configurations wrapped on a torus and gauge theories with a constant background field on the dual torus .
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Suppose that you have an abstract for a scientific paper: consider an asymptotically flat riemannian manifold @xmath0 of dimension @xmath1 with nonempty compact boundary .
we recall the harmonic conformal class @xmath2_h$ ] of the metric , which consists of all conformal rescalings given by a harmonic function raised to an appropriate power .
the geometric significance is that every metric in @xmath2_h$ ] has the same pointwise sign of scalar curvature .
for this reason , the harmonic conformal class appears in the study of general relativity , where scalar curvature is related to energy density ( c.f .
@xcite ) . our purpose is to introduce and study invariants of the harmonic conformal class .
these invariants are closely related to constrained geometric optimization problems involving hypersurface area - minimizers and the adm mass . in the final section , we discuss possible applications of the invariants and their relationship with zero area singularities and the positive mass theorem . .
And you have already written the first three sentences of the full article: let @xmath3 be a smooth manifold of dimension @xmath1 , possibly with a smooth boundary @xmath4 .
recall that two riemannian metrics @xmath5 and @xmath6 on @xmath3 are _ conformal _ if there exists a smooth function @xmath7 on @xmath3 such that @xmath8 pointwise as quadratic functions on the fibers of @xmath9 .
conformality is obviously an equivalence relation , with the equivalence class of a metric @xmath5 called the _.
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conformal class _ of @xmath5 : @xmath10 = \left\{u^{\frac{4}{n-2 } } g : u > 0 \text { is a smooth function on } m\right\}.\ ] ] the conformal class is an indispensable object in geometric analysis . in the proof of the riemannian penrose inequality @xcite ,
bray observed the following fact : the relation on riemannian metrics @xmath11 defined by @xmath12 is an equivalence relation .
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Suppose that you have an abstract for a scientific paper: recent improvements to the limit of @xmath0 imply that pure superweak theories , while not excluded , no longer provide a good fit to the data . a class of general superweak theories is introduced in which all flavor changing interactions are governed by an approximate flavor symmetry which gives a `` 3 mechanism '' .
these theories are in good agreement with data , and predict low values for @xmath1 and cp asymmetries in b decays , and high values for @xmath0 and @xmath2 .
an important example of such a theory is provided by weak scale supersymmetric theories with soft @xmath3 violation .
the @xmath3 violation originates in the squark mass matrix , and , with phases of order unity , flavor symmetries can yield a correct prediction for the order of magnitude of @xmath4 . plus 1000pt minus 1000pt # 1 # 1= to # 1#2#1#2 # 1#2#3 ^ 2 # 1#2 # 3 # 1#1| # 1| # 1 # 1#1 # 1/ # 1| # 1| # 1#1^ lbnl-41104 + ucb - pth-97/57 + sns / ph/1997 - 8 + lal 97 - 91 .25 in * alternative theories of cp violation * 0.3 in riccardo barbieri@xmath5 , lawrence hall@xmath6 , achille stocchi@xmath7 , and neal weiner@xmath6 0.1 in @xmath5 _ scuola normale superiore , pisa , italy ; + and infn , sezione di pisa , italy + _ 0.1 in @xmath6 _ department of physics and lawrence berkeley national laboratory + university of california , berkeley , california 94720 + _ 0.1 in @xmath7 _ laboratoire de lacclrateur linaire + in2p3-cnrs et universit de paris - sud , f-91405 orsay _ .3 in .
And you have already written the first three sentences of the full article: all observed cp violation can be described by the complex parameter @xmath4 , which describes an imaginary contribution to the @xmath8 mixing of the neutral @xmath9 mesons .
such a mixing implies the existence of an effective hamiltonian @xmath10 where @xmath11 gev , and @xmath12 run over possible gamma matrix structures .
the dimensionless coefficients @xmath13 are real in a basis where the standard model @xmath14 effective hamiltonian has a real coefficient . in the case.
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that the dominant term is @xmath15 , @xmath16 the two basic issues of cp violation are * what is the underlying physics which leads to @xmath17 ? is it a very small effect originating at the weak scale , as suggested by the form @xmath18 , or is it a larger effect generated by physics at higher energies ? * how can the magnitude @xmath19 to @xmath20 be understood ?
in the standard model all information about flavor and cp violation originates from the yukawa coupling matrices .
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Suppose that you have an abstract for a scientific paper: we studied coherent backscattering ( cbs ) of light from opal photonic crystals in air at different incident inclination angles , wavelengths and along various @xmath0 $ ] directions inside the opals .
similar to previously obtained cbs cones from various random media , we found that when bragg condition with the incident light beam is not met then the cbs cones from opals show a triangular line shape in excellent agreement with light diffusion theory . at bragg condition , however , we observed a dramatic broadening of the opal cbs cones that depends on the incident angle and @xmath0 $ ] direction .
this broadening is explained as due to the light intensity decay in course of propagation along the bragg direction _ before the first _ and _ after the last _ scattering events .
we modified the cbs theory to incorporate the attenuation that results from the photonic band structure of the medium .
using the modified theory we extract from our cbs data the light mean free path and bragg attenuation length at different @xmath0 $ ] .
our study shows that cbs measurements are a unique experimental technique to explore photonic crystals with disorder , when other spectroscopical methods become ambiguous due to disorder - induced broadening . .
And you have already written the first three sentences of the full article: expreimental studies of coherent backscattering ( cbs ) of light from disordered media have been completed by many groups during the last decade.@xmath1 cbs measurements are of great interest because they have allowed to test the physics of weak localization , which was first uncovered in electronic transport,@xcite when applied to light waves and also to determine the light mean - free - path , @xmath2 in random media . in cbs measurements
the normalized reflected light intensity ( also called the albedo , @xmath3 ) is monitored versus the deviation angle , @xmath4 from the backscattering direction of the incident laser beam . in the multiple scattering regime interference effects are averaged out except in a small angular range around @xmath5 , where constructive interference originating from reciprocal light paths enhance the diffusive reflection from the sample . as a result a coherent scattering intensity cone is formed in the albedo , @xmath6 for small @xmath7 . from the full width , @xmath8 of the cbs cone at quarter maximum , @xmath2 is obtained using the relation @xmath9 , where @xmath10 is the impinging laser wavelengh .
the first cbs measurements were performed on suspensions of polystyrene spheres.@xcite since the suspension particles were very small in diameter , their brownian motion provided a natural ensemble averaging . for solid materials.
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, however cbs usually shows a noisy but repeatable mesoscopic pattern.@xcite under these conditions the cbs cone around @xmath5 can be obtained by applying an elaborate ensemble - averaging technique in order to suppress the dominant mesoscopic fluctuations . the averaging techniques employed to get the cone include spot variation,@xcite tilt angle variation,@xcite and sample spin - rotation.@xcite all the above experimental studies@xmath1 were performed on completely disordered , isotropic and homogeneous media .
photonic crystals have recently attracted a lot of attention@xcite because of potential optical device applications .
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Suppose that you have an abstract for a scientific paper: millimeter wave channels suffer from considerable degradation in the channel quality when the signal is non line of sight ( nlos ) between the source and the destination .
multihop relaying is thus anticipated to improve the communication between a source and its destination .
this is achieved by transmitting the signal to a sequence of relays in which a line of sight ( los ) signal exists between two nodes along the path , or more generally when the signal is better than the transmitted signal directly from the source to the destination . in this paper
, we consider a millimeter wave network composed of multiple source - destination pairs and a set of deployed relays .
we formulate the problem of multihop relaying as a cooperative network formation game in which each relay chooses which source - destination pair to assist in order to improve the end - to - end performance , that is , the multihop delay between the source and the destination .
further , we present an algorithm based on the nash bargaining solution to ensure fairness among the different source - destination pairs and assess its efficiency on numerical simulations . .
And you have already written the first three sentences of the full article: the interest in millimeter wave communications has been tremendously increased as a viable technology for fifth generation wireless cellular systems .
this is due to the fact that millimeter wave communications support the very high data rates necessary for broadband and multimedia communications thanks to the availability of large bandwidth at the high frequencies .
however , communications at these high frequencies suffer from two main drawbacks ..
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the first is that the millimeter wave signal suffers from severe pathloss . to overcome this
, there is an active research going on designing beamforming techniques in order to extend the signal range and enable communication between the targeted transmitter and receiver @xcite-@xcite .
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Suppose that you have an abstract for a scientific paper: we suggest a new model of @xmath0 kev right - handed neutrino dark matter inspired by a recent observation of @xmath1 x - ray line signal in the xmm - newton observatory .
it is difficult to derive the tiny masses with a suitable left - right mixing of the neutrino in a framework of ordinary simple type - i seesaw mechanism .
we introduce a new higgs boson , a dark matter - philic higgs boson , in which the smallness of its vacuum expectation value can be achieved .
we investigate suitable parameter regions where the observed dark matter properties are satisfied .
we find that the vacuum expectation value of dark matter - philic higgs boson should be about @xmath2
. 0.6 cm su - het-09 - 2014 * @xmath3 dark matter - philic higgs for 3.5 kev x - ray signal * 1.2 cm naoyuki haba , hiroyuki ishida and ryo takahashi 0.4 cm _ graduate school of science and engineering , shimane university , matsue , 690 - 8504 japan _ 0.2 cm .5 in .
And you have already written the first three sentences of the full article: the existence of dark matter ( dm ) is confirmed by a lot of astrophysical observations . however , there is no candidate in the standard model ( sm ) particle content .
one of properties required for dm is a long lifetime which should be longer than the age of our universe . to realize this stability
, an additional symmetry should be exist ..
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for example , when the dm particle has odd parity and others do even parity under a @xmath4 symmetry , the dm particle can be stable .
recent analyses of the observation of x - ray from the perseus galaxy clusters and the andromeda galaxy by the xmm - newton observatory reported an unknown x - ray line spectrum around @xmath1 @xcite .
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Suppose that you have an abstract for a scientific paper: since the first tev blazar markarian ( mrk ) 421 was detected in 1992 , the number of established tev @xmath0-ray emitting bl lac objects has grown to 6 , with redshifts ranging from 0.031 ( mrk 421 ) to 0.129 ( h 1426 + 428 ) .
the intensive study of these sources has had a major impact on our understanding of the blazar phenomenon .
the most notable observational results have been extremely fast large amplitude flux and spectral variability on hour time scales , and a pronounced x - ray - tev @xmath0-ray flux correlation . in this paper
we discuss recent observational results and report on progress in their theoretical interpretation .
galaxies : bl lacertae objects galaxies : jets gamma rays : observations gamma rays : theory .
And you have already written the first three sentences of the full article: the egret _ ( energetic gamma ray experiment telescope ) _ detector on board of the _ compton gamma - ray observatory _ discovered strong mev @xmath0-ray emission from 66 blazars , mainly from flat spectrum radio quasars and unidentified flat spectrum radio sources @xcite .
ground - based cherenkov telescopes discovered tev @xmath0-ray emission from 6 blazars , 4 of which have not been detected by egret .
all the established tev detections belong to the class of bl lac objects , blazars with relatively low luminosity but with spectral energy distributions ( seds ) that peak at extremely high energies ( see table [ detect ] ) ..
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+ .tev blazars with a significant detection by at least 2 experiments ( as of july 2003 ) . [ cols="^,^,^",options="header " , ] the large detection area of cherenkov telescopes of @xmath110@xmath2 m@xmath3 makes it possible to sample the @xmath0-ray lightcurves with a time resolution of several minutes . large amplitude flux variability on 30 min time scales implies that the tev emission originates from a small region very near the supermassive black hole @xcite .
the relativistic doppler factor of the emitting plasma is defined as @xmath4 , where @xmath5 is the bulk lorentz factor of the emitting plasma , @xmath6 is its bulk velocity in units of the speed of light , and @xmath7 is the angle between jet axis and the line of sight as measured in the observer frame .
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Suppose that you have an abstract for a scientific paper: a recent progress in the study of @xmath0-ray jets is reviewed , with a focus on some theoretical interpretations of the vhe emission from m87 , and possibly other misaligned blazars ; the connection between the gev breaks exhibited by bright lat blazars and opacity sources in the broad line region ; the consequences of the detection of gev emission from grbs to models of magnetic outflows ; and the implications of the thermal emission observed is some grbs to dissipation of the outflow bulk energy . .
And you have already written the first three sentences of the full article: observations by fermi and the various tev experiments , and advances in numerical techniques have led to a progress in our understanding of relativistic jets : i ) in m87 , combined vlba and tev data ( acciari et al .
2009 ) seem to indicate that the tev emission is produced on horizon scales by either some magnetospheric process , or at the base of the vlba jet .
the observational constraints raise interesting questions about the structure of the bh magnetosphere and the jet formation mechanism , that appear to be relevant also to other tev agns ..
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ii ) the lat spectrum of blazars provide now a better than before probe of opacity sources on sub - parsec scales .
the data reveal relationship between source power and spectral features that can be interpreted in terms of blr properties .
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Suppose that you have an abstract for a scientific paper: we report on the @xmath0 scattering length in the @xmath1 channel using the parametrized fixed point ( p - fp ) action .
pion masses of 320 mev were reached in this quenched calculation of the scattering length . .
And you have already written the first three sentences of the full article: the pion scattering length is an important observable characterizing dynamical effects of the strong interaction and its ab initio calculation on the lattice is an important nonperturbative test of qcd . in the literature several attempts to compute the scattering length with wilson fermions @xcite and staggered fermions @xcite can be found .
however , calculations with a chiral dirac operator which allows for a better control of the small mass region are still missing . in full qcd the scattering length is a quantity which vanishes in the chiral limit , while it is power divergent in the quenched theory @xcite and eventually a study in the full theory is desirable . in this contribution
, we present results of the scattering length calculated using the p - fp action ..
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( calculations with chirally improved fermions is also underway . )
the chiral and scaling properties of the light hadron spectrum using p - fp and chirally improved actions were reported by the collaboration in an earlier publication @xcite .
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Suppose that you have an abstract for a scientific paper: sliding window is one direct way to extend a successful recognition system to handle the more challenging detection problem . while action recognition decides only whether or not an action is present in a pre - segmented video sequence , action detection identifies the time interval where the action occurred in an unsegmented video stream .
sliding window approaches can however be slow as they maximize a classifier score over all possible sub - intervals .
even though new schemes utilize dynamic programming to speed up the search for the optimal sub - interval , they require offline processing on the whole video sequence . in this paper
, we propose a novel approach for online action detection based on 3d skeleton sequences extracted from depth data .
it identifies the sub - interval with the maximum classifier score in linear time .
furthermore , it is suitable for real - time applications with low latency . .
And you have already written the first three sentences of the full article: human action detection at real - time has become a topic of increasing interest due to its wide practical use .
applications like human - machine interaction , surveillance and gaming , all require accurate and low - latency action detection .
action detection on raw videos is difficult because it is first needed to localize a person in a scene full of objects and clutter , then try to recognize the type of action being performed . on the other hand , the recent low - cost depth sensors , like microsoft kinect , provided a more convenient way for data capture ..
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the 3d positions of body joints can be estimated from depth maps at low - latency and with acceptable accuracy .
filtering out background clutter , it is now more adequate to perform action detection based on skeleton data .
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Suppose that you have an abstract for a scientific paper: experiments with pedestrians could depend strongly on initial conditions
. comparisons of the results of such experiments require to distinguish carefully between transient state and steady state . in this work , a feasible algorithm - cumulative sum control chart
- is proposed and improved to automatically detect steady states from density and speed time series of bottleneck experiments .
the threshold of the detection parameter in the algorithm is calibrated using an autoregressive model . comparing the detected steady states with previous manually selected ones
, the modified algorithm gives more reproducible results .
for the applications , three groups of bottleneck experiments are analysed and the steady states are detected .
the study about pedestrian flow shows that the difference between the flows in all states and in steady state mainly depends on the ratio of pedestrian number to bottleneck width .
when the ratio is higher than a critical value ( approximately 115 persons / m ) , the flow in all states is almost identical with the flow in steady state .
thus we have more possibilities to compare the flows from different experiments , especially when the detection of steady states is difficult .
keywords : bottleneck , experiments , flow , steady state , cusum .
And you have already written the first three sentences of the full article: in recent years , several experiments under well - controlled laboratory conditions were carried out to explore pedestrian characteristics in bottlenecks .
most experiments focused on the relationship between bottleneck width and pedestrian flow @xcite .
the flow was once announced to grow in a stepwise manner along with lane formation @xcite ..
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however , it was shown afterwards by more detailed experiments to be linearly dependent on bottleneck width .
the slope of the linear function is approximately 1.9 ( m@xmath0s)@xmath1 with bottleneck width ranging from 0.7 m to 5.0 m @xcite . when bottleneck width is smaller than 0.7 m , the slope of the linear function decreases with increasing bottleneck width @xcite .
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Suppose that you have an abstract for a scientific paper: we investigate the interiors of 3 + 1 dimensional asymptotically flat charged and rotating black holes as described by observers who fall into the black holes at late times , long after any perturbations of the exterior region have decayed . in the strict limit of late infall times , the initial experiences of such observers are precisely described by the region of the limiting stationary geometry to the past of its inner horizon . however , we argue that late infall - time observers encounter a null shockwave at the location of the would - be outgoing inner horizon .
in particular , for spherically symmetric black hole spacetimes we demonstrate that freely - falling observers experience a metric discontinuity across this shock , that is , a _ gravitational shock - wave_. furthermore , the magnitude of this shock is at least of order unity .
a similar phenomenon of metric discontinuity appears to take place at the inner horizon of a generically - perturbed spinning black hole .
we compare the properties of this null shockwave singularity with those of the null weak singularity that forms at the cauchy horizon . .
And you have already written the first three sentences of the full article: in einstein - hilbert gravity coupled to various matter fields , the exterior geometry of a 3 + 1 dimensional asymptotically flat black hole ( bh ) spacetime typically approaches a stationary solution at late times .
non - stationary perturbations decay both by falling across the horizon and dispersing to infinity , as described by the ringdown of quasi - normal modes followed by power - law tails .
our purpose here is to explore a corresponding late - time limit of the associated black hole interiors ..
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we will argue that as far as the observations of late - infalling physical observers are considered , the result is well - described by a simple effective geometry which contains the part of the corresponding stationary bh solution to the past of the inner horizon .
however , the regular inner horizon is replaced by singular components of two different types : ( i ) the _ ingoing _ section of the inner horizon the cauchy horizon ( ch)is replaced by a null , weak , curvature singularity , and ( ii ) the _ outgoing _ section of the inner horizon is replaced by an outgoing shock - wave singularity .
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Suppose that you have an abstract for a scientific paper: we present an ` a`daptively ` b`iased ` m`olecular ` d`ynamics ( ` abmd ` ) method for the computation of the free energy surface of a reaction coordinate using non - equilibrium dynamics .
the ` abmd ` method belongs to the general category of umbrella sampling methods with an evolving biasing potential , and is inspired by the metadynamics method .
the ` abmd ` method has several useful features , including a small number of control parameters , and an @xmath0 numerical cost with molecular dynamics time @xmath1 .
the ` abmd ` method naturally allows for extensions based on _ multiple walkers _ and _ replica exchange _ , where different replicas can have different temperatures and/or collective variables . this is beneficial not only in terms of the speed and accuracy of a calculation , but also in terms of the amount of useful information that may be obtained from a given simulation .
the workings of the ` abmd ` method are illustrated via a study of the folding of the peptide in a gaseous and solvated environment . .
And you have already written the first three sentences of the full article: when investigating the equilibrium properties of a complex polyatomic system , it is customary to identify a suitable _ reaction coordinate _ @xmath2 that maps atomic positions @xmath3 onto the points of some manifold @xmath4 , and then to study its equilibrium probability density : @xmath5\big>,\ ; \xi\in\mathbb{q}\ ] ] ( angular brackets denote an ensemble average ) .
the density @xmath6 provides information about the relative stability of states corresponding to different values of @xmath7 along with useful insights into the transitional kinetics between various stable states . in practice , the landau free energy@xcite @xmath8 is typically preferred over @xmath6 , because it tends to be more intuitive .
either @xmath6 or @xmath9 is said to provide a coarse - grained description of the system in terms of @xmath7 alone with the rest of the degrees of freedom of the original system integrated out ..
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quite naturally , the reaction coordinate ( often also referred to as _ collective variable _ or _ order parameter _ ) is typically chosen to represent the slowest degrees of freedom of the original system , although this is not formally required . in the past few years
, several methods targeting the computation of @xmath9 using non - equilibrium dynamics have become popular .
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Suppose that you have an abstract for a scientific paper: the very high energy ( vhe ; @xmath0100 gev ) source hess j0632 + 057 has been recently confirmed as a @xmath1-ray binary , a subclass of the high mass x - ray binary ( hmxb ) population , through the detection of an orbital period of 321 days .
we performed a deep search for the emission of hess j0632 + 057 in the gev energy range using data from the _ fermi _ large area telescope ( lat ) .
the analysis was challenging due to the source being located in close proximity to the bright @xmath1-ray pulsar psr j0633 + 0632 and lying in a crowded region of the galactic plane where there is prominent diffuse emission .
we formulated a bayesian block algorithm adapted to work with weighted photon counts , in order to define the off - pulse phases of psr j0633 + 0632 .
a detailed spectral - spatial model of a 5@xmath2 circular region centred on the known location of hess j0632 + 057 was generated to accurately model the lat data .
no significant emission from the location of hess j0632 + 057 was detected in the 0.1100 gev energy range integrating over @xmath33.5 years of data ; with a 95% flux upper limit of f@xmath4 @xmath5 ph @xmath6 s@xmath7 . a search for emission over different phases of
the orbit also yielded no significant detection . a search for source emission on shorter timescales ( days months ) did not yield any significant detections .
we also report the results of a search for radio pulsations using the 100-m green bank telescope ( gbt ) .
no periodic signals or individual dispersed bursts of a likely astronomical origin were detected .
we estimated the flux density limit of @xmath8jy at 2/9ghz .
the lat flux upper limits combined with the detection of hess j0632 + 057 in the 136400 tev energy band by the magic collaboration imply that the vhe spectrum must turn over at energies @xmath9136 gev placing constraints on any theoretical models invoked to explain the @xmath1-ray emission .
[ firstpage ] binaries : individual : hess j0632 + 057 gamma - rays : observations ....
And you have already written the first three sentences of the full article: the population of @xmath1-ray binaries is a subclass of the high mass x - ray binary ( hmxb ) population ; they are binary systems comprised of a high mass ( @xmath10 m@xmath11 ) star and a compact object whose spectral energy distribution ( sed ) peaks above 1 mev .
indeed , they exhibit emission at high energies ( he ; 0.1100 gev ) and/or very high - energies ( vhe ; @xmath0100 gev ) .
the non - thermal high energy radiation from these objects indicates that they are sites of natural particle acceleration . at present only a handful of confirmed @xmath1-ray binaries are known : * ls i + 61@xmath2303 @xcite * ls5039 @xcite * psr b1259@xmath1263 * hess j0632 + 057 @xcite * 1fgl j1018.6@xmath125856 @xcite cyg x@xmath123 @xcite and cyg x@xmath121 @xcite show @xmath1-ray flaring activity , but their seds are peaked in x - rays ..
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so they do not belong to the population of the @xmath1-ray binaries .
ls i + 61@xmath2303 , ls5039 and psr b1259@xmath1263 have all been detected at both gev and tev energies ; 1fgl j1018.6@xmath12585 was discovered at gev energies solely with data from the _ fermi gamma - ray space telescope _ large area telescope ( _ fermi_-lat ) and has recently been reported to have a possible tev counterpart , hess j1018@xmath12589 @xcite .
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Suppose that you have an abstract for a scientific paper: a thin and dense plasma layer is created when a sufficiently strong laser pulse impinges on a solid target .
the nonlinearity introduced by the time - dependent electron density leads to the generation of harmonics .
the pulse duration of the harmonic radiation is related to the risetime of the electron density and thus can be affected by the shape of the incident pulse and its peak field strength .
results are presented from numerical particle - in - cell - simulations of an intense laser pulse interacting with a thin foil target . an analytical model which shows how the harmonics are created is introduced .
the proposed scheme might be a promising way towards the generation of attosecond pulses .
+ pacs number(s ) : 52.40.nk , 52.50.jm , 52.65.rr # 1#2 _ null_0 # 1 # 1#2 # 1#2 # 1([#1 ] ) .
And you have already written the first three sentences of the full article: in recent years several mechanisms generating harmonics of electromagnetic radiation have been discovered . among these harmonics from gases @xcite , harmonics from a laser pulse propagating through underdense plasma @xcite , and harmonics production from the plasma - vacuum boundary when a laser pulse impinges on a solid target @xcite are the most prominent ones .
especially the high - order gas - harmonics , exhibiting a `` plateau '' instead of a rapid decrease with the harmonic order , seem to be a promising source for xuv `` water - window''-radiation . apart from the effort to make progress towards shorter wavelengths , another goal is to achieve shorter pulse durations because the temporal resolution in pump - probe experiments clearly depends on the pulse length .
one scheme proposed to generate attosecond pulses is based on phase - matching pulse trains which are produced by a laser pulse focused into a jet of rare gases @xcite ..
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another method makes use of the fact that the efficiency of gas - harmonics generation is sensitive to the ellipticity of the incident laser light @xcite .
the method to generate an ultra - short _ low order _ harmonic laser pulse as proposed in this paper is based on the time - dependent electron density of the target material in laser pulse - solid interaction .
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Suppose that you have an abstract for a scientific paper: we consider general locally - interacting arbitrary - dimensional lattice spin systems that are gapped for any system size .
we show under reasonable conditions that nondegenerate ground states of such systems obey the entanglement area law . in so doing ,
we offer an intuitive picture on how a spectral gap restricts the correlations that a ground state can accommodate and leads to such a special feature . over the last decade or so
, quantum information theory has emerged as an indispensable tool in studying strongly - correlated many - body systems .
for example , entanglement is essential in classifying quantum phases of matter @xcite , especially topological quantum phases @xcite , the density matrix renormalization group ( dmrg ) method provides the best way to numerically simulate low energy physics of one - dimensional spin systems @xcite , and various universal features of general many - body systems have been explored with new tools and insights @xcite . while there are many different avenues in such quantum information approaches to many - body physics , they are essentially built upon the grounds of common theoretical foundations .
the entanglement area law ( or simply the area law ) is one of the prominent @xcite . for a many - body pure state @xmath0 ,
the bipartite entanglement between a subregion ( @xmath1 ) and the rest ( @xmath2 ) is quantified by the entanglement entropy @xmath3 , the von neumann entropy of the reduced density matrix @xmath4 .
when @xmath3 has an upper bound proportional to the surface area of @xmath1 , we say @xmath0 obeys the area law @xcite .
it turns out that ground states of local hamiltonians typically obey the area law @xcite , possibly with a multiplicative logarithmic correction @xcite , although one can deliberately construct a counterexample @xcite .
the area law is indeed a very special feature because in a large hilbert space , almost all states , in the sense of the haar measure , exhibit a volume - law scaling of the....
And you have already written the first three sentences of the full article: consider a system of 4-dimensional spins with basis states @xmath191 .
suppose the hamiltonian is written as @xmath192 where @xmath193 contains only @xmath194 , while @xmath195 contains only @xmath196 .
both @xmath193 and @xmath195 are gapped with a minimal gap @xmath13 , but the ground state energy of @xmath193 is zero for @xmath197 and @xmath13 for @xmath198 , whereas that of @xmath195 is @xmath13 for @xmath197 and zero for @xmath198 . the ground state is then spanned by @xmath194 for @xmath197 and by @xmath196 for @xmath198 . in this case , the overlap between @xmath199 and @xmath200 vanishes for any @xmath201 ..
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consider a mapping from @xmath15 to @xmath14 , as in fig . 1 of the main text .
as the hamiltonian @xmath9 differs from @xmath38 only by a local term @xmath202 , it is reasonable to approximate @xmath14 with @xmath79 by finding an optimal unitary operator @xmath203 supported on @xmath81 so that the approximation gets better as @xmath83 is increased .
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Suppose that you have an abstract for a scientific paper: in models with one universal extra dimension ( ued ) , the first kaluza - klein excitations of the hypercharge gauge boson , @xmath0 , and the neutral component of isospin gauge boson , @xmath1 , are each viable dark matter candidates . in either case , such particles are predicted to accumulate in the core of the sun , where they annihilate to generate a potentially observable flux of high energy neutrinos . in this article , we calculate the flux of neutrinos produced in this model and determine the constraints that can be placed on the ued parameter space from current icecube data . for the case of @xmath0 dark matter , we find that the present limits from icecube are stronger than those from direct dark matter detection experiments such as cdms and xenon10 . for @xmath1 dark matter ,
the present icecube data provides a constraint slightly weaker than direct detection experiments .
in addition , we also present the projected regions of ued parameter space that can be probed by icecube / deepcore in the near future and compare them to the prospects for future direct detection experiments . .
And you have already written the first three sentences of the full article: in models with one universal extra dimension ( ued ) @xcite , all of the standard model particles are promoted to 5 dimensional fields , propagating in a flat extra dimension ( for earlier ideas closely related to ued models see ref .
@xcite ) . in order to allow for the existence of chiral zero - mode fermions , the extra dimension is modded out by the orbifold , @xmath2 . due to the @xmath3 symmetry ,
the interactions between kaluza - klein ( kk ) modes respect what is known as kk - parity , which implies that kaluza - klein particles can only be produced or destroyed in pairs . among other consequences.
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, this leads to a lower bound on the kk mass scale of only @xmath4 @xcite .
furthermore , kk - parity guarantees the stability of the lightest kaluza - klein particle ( lkp ) , thus providing us with a potentially viable dark matter candidate . for a review of the ued model and its phenomenology , see ref .
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Suppose that you have an abstract for a scientific paper: we propose a general framework for reconstructing and denoising single entries of incomplete and noisy entries .
we describe : effective algorithms for deciding if and entry can be reconstructed and , if so , for reconstructing and denoising it ; and a priori bounds on the error of each entry , individually . in the noiseless case
our algorithm is exact . for rank - one matrices ,
the new algorithm is fast , admits a highly - parallel implementation , and produces an error minimizing estimate that is qualitatively close to our theoretical and the state - of - the - are nuclear norm and optspace methods .
= 1 .
And you have already written the first three sentences of the full article: matrix completion is the task to reconstruct low - rank matrices from a subset of its entries and occurs naturally in many practically relevant problems , such as missing feature imputation , multi - task learning @xcite , transductive learning @xcite , or collaborative filtering and link prediction @xcite .
almost all known methods performing matrix completion are optimization methods such as the max - norm and nuclear norm heuristics @xcite , or optspace @xcite , to name a few amongst many .
these methods have in common that in general ( a ) they reconstruct the whole matrix and ( b ) error bounds are given for all of the matrix , not single entries ..
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these two properties of existing methods are in particular unsatisfactory in the scenario when one is interested only in predicting ( resp . imputing ) one single missing entry or a set of interesting missing entries instead of all - which is for real data a more natural task than imputing all missing entries , in particular in the presence of large scale data ( resp .
big data ) .
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Suppose that you have an abstract for a scientific paper: the mollification @xmath0 put forward by feng is computed by analytic methods coming from the techniques of the ratios conjectures of @xmath1-functions .
the current situation regarding the percentage of non - trivial zeros of the riemann zeta - function on the critical line is then clarified . .
And you have already written the first three sentences of the full article: the riemann zeta - function @xmath2 is defined by the dirichlet series @xmath3 for @xmath4 , @xmath5 and @xmath6 .
the functional equation of @xmath2 is given by @xmath7 where @xmath8 this allows us to perform a meromorphic continuation to the whole complex plane except at @xmath9 where @xmath2 has a simple pole with residue equal to @xmath10 .
the connection with number theory comes from the euler product @xmath11 for @xmath12 , and where the product is taken over all the primes @xmath13 ..
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it is well - known from riemann and from von mangoldt that the non - trivial zeros @xmath14 of @xmath2 are located inside the critical strip @xmath15 .
moreover , if @xmath16 denotes the number of such zeros up to height @xmath17 then @xmath18 where @xmath19 as @xmath20 , see e.g. @xcite for properties of @xmath2 . to state the results , we let @xmath21 denote the number of non - trivial zeros up to height @xmath22 such that @xmath23 . similarly , let @xmath24 denote the number such zeros which are also simple .
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Suppose that you have an abstract for a scientific paper: we have studied the x - ray luminosity function ( xlf ) of low - mass x - ray binaries ( lmxbs ) in the nearby lenticular galaxy ngc 3115 , using the megasecond _ chandra _ x - ray visionary project observation . with a total exposure time of @xmath01.1 ms
, we constructed the xlf down to a limiting luminosity of @xmath0@xmath1 erg s@xmath2 , much deeper than typically reached for other early - type galaxies .
we found significant flattening of the overall lmxb xlf from @xmath3 above @xmath4 erg s@xmath2 to @xmath5 below it , though we could not rule out a fit with a higher break at @xmath0@xmath6 erg s@xmath2 .
we also found evidence that the xlf of lmxbs in globular clusters ( gcs ) is overall flatter than that of field lmxbs .
thus our results for this galaxy do not support the idea that all lmxbs are formed in gcs .
the xlf of field lmxbs seems to show spatial variation , with the xlf in the inner region of the galaxy being flatter than that in the outer region , probably due to contamination of lmxbs from undetected and/or disrupted gcs in the inner region .
the xlf in the outer region is probably the xlf of primordial field lmxbs , exhibiting @xmath7 up to a break close to the eddington limit of neutron star lmxbs ( @xmath0@xmath8 erg s@xmath2 ) .
the break of the gc lmxb xlf is lower , at @xmath0@xmath9 erg s@xmath2 .
we also confirm previous findings that the metal - rich / red gcs are more likely to host lmxbs than the metal - poor / blue gcs , which is more significant for more luminous lmxbs , and that more massive gcs are more likely to host lmxbs . .
And you have already written the first three sentences of the full article: population studies of x - ray binaries in nearby galaxies have been made possible thanks to the superb spatial resolution and excellent sensitivity of the _ chandra x - ray observatory _ @xcite .
the x - ray luminosity functions ( xlfs ) of point sources have been obtained for many galaxies , and they are found to be environment dependent ( see * ? ? ? * for a review ) . in young normal galaxies , high - mass x - ray binaries ( hmxbs )
dominate , and the xlfs follow a simple power law ( pl ) @xmath10 with @xmath11 over a large range of luminosity : @xmath12 erg s@xmath2 @xmath13 erg s@xmath2 @xcite ..
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in old normal galaxies or in the bulge of young normal galaxies , low - mass x - ray binaries ( lmxbs ) dominate , and the xlfs seem relatively complicated , showing both a high - luminosity break at @xmath14 erg s@xmath2 @xcite and a low - luminosity break at @xmath15 erg s@xmath2 @xcite .
the slope between these two breaks is @xmath161.82.2 . above the high - luminosity break ,
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Suppose that you have an abstract for a scientific paper: in the chiral quark soliton model the smallness of @xmath0 width is due to the cancellation of the coupling constants which are of different order in @xmath1 .
we show that taking properly into account the flavor structure of relevant su(3 ) representations for arbitrary number of colors enhances the nonleading term by an additional factor of @xmath1 , making the cancellation consistent with the @xmath1 counting .
moreover , we show that , for the same reason , @xmath0 width is suppressed by a group - theoretical factor @xmath2 with respect to @xmath3 and discuss the @xmath1 dependence of the phase space factors for these two decays .
tpju-11/2003 + bnl - nt-03/38 .
And you have already written the first three sentences of the full article: recently five experiments announced discovery of a narrow , exotic baryonic state called @xmath4 @xcite .
most probably this state belongs to the positive parity baryon antidecuplet , which naturally emerges in chiral soliton models @xcite .
early prediction of its mass @xcite obtained in the skyrme model @xcite extended to three flavors @xcite is in surprising agreement with the present experimental findings ..
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moreover , if the discovery of the heaviest members of the antidecuplet , @xmath5 , announced by na49 collaboration @xcite at 1860 mev is confirmed , again the same model will be off only by 70 mev @xcite .
however , the most striking experimental result is perhaps a very small width @xmath6 which is estimated to be of the order of a few tens mev or less @xcite .
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Suppose that you have an abstract for a scientific paper: we have included opacity tables in our stellar evolution code that enable us to accurately model the structure of stars composed of mixtures with carbon and oxygen independently enhanced relative to solar .
we present tests to demonstrate the effects of the new tables .
two of these are practical examples , the effect on the evolution of a thermally pulsing asymptotic giant branch star and a wolf - rayet star .
the changes are small but perceptible .
[ firstpage ] radiative transfer stars : carbon stars : evolution stars : general stars : agb stars : wolf - rayet .
And you have already written the first three sentences of the full article: the main source of a star s energy is the nuclear fusion reactions occurring either in its core or in thin burning shells around the core .
this energy is transported from the production site to the surface by radiative transfer or convection .
the first transports energy in the form of photons , while the second is a cyclic macroscopic mass motion that carries the energy in bulk . in regions where convection is stabilised.
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, radiative transfer leads to the equation of stellar structure , @xmath0 where @xmath1 is the luminosity at radius @xmath2 , @xmath3 the density , @xmath4 the stefan - boltzmann constant , @xmath5 the temperature and @xmath6 is the rosseland mean opacity .
opacity @xmath7 is a measure of the degree to which matter absorbs photons .
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Suppose that you have an abstract for a scientific paper: we discuss the effects of superfluidity on the shear viscosity in a neutron star core .
our study combines existing theoretical results for the viscosity coefficients with data for the various superfluid energy gaps into a consistent description .
in particular , we provide a simple model for the electron viscosity which is relevant both when the protons form a normal fluid and when they become superconducting .
this model explains in a clear way why proton superconductivity leads to a significant strengthening of the shear viscosity .
we present our results in a form which permits the use of data for any given modern equation of state ( our final formulas are explicitly dependent on the proton fraction ) .
we discuss a simple description of the relevant superfluid pairing gaps , and construct a number of models ( spanning the range of current uncertainty ) which are then used to discuss the superfluid suppression of shear viscosity .
we conclude by a discussion of a number of challenges that must be met if we are to make further progress in this area of research . .
And you have already written the first three sentences of the full article: neutron stars are often thought of as exciting cosmic laboratories .
this is natural since their description depends on much complex physics @xcite : with a mass of about one and a half times that of the sun compressed inside a radius of ten kilometers or so , they are compact enough to require a fully general relativistic description . with central densities several times the nuclear saturation density it may be energetically favourable for exotic phases of matter , like kaon condensates , hyperons and/or deconfined quarks , to be present in the core . with temperatures much below the fermi temperature for the various constituents , neutron stars are cold on the nuclear scale which means that the presence of both solid ( the outer layers form a kilometer sized nuclear lattice ) and superfluid regions is expected .
neutron star dynamics is also intriguing ..
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the obvious example of this is the glitches , which are taken as evidence of at least two weakly coupled interior components , observed in a number of radio pulsars @xcite .
in addition , the evolution of the sample of the neutron star population which is spinning rapidly may be affected by both hydrodynamical and/or radiation - driven instabilities @xcite .
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Suppose that you have an abstract for a scientific paper: in recent publications , the authors have considered inverse statistics of the dow jones industrial averaged ( djia ) @xcite .
specifically , we argued that the natural candidate for such statistics is the investment horizons distribution .
this is the distribution of waiting times needed to achieve a predefined level of return obtained from detrended historic asset prices .
such a distribution typically goes through a maximum at a time coined the
_ optimal investment horizon _ , @xmath0 , which defines the most likely waiting time for obtaining a given return @xmath1 .
by considering equal positive and negative levels of return , we reported in @xcite on a quantitative gain / loss asymmetry most pronounced for short horizons . in the present paper , this gain / loss asymmetry is re - visited for 2/3 of the individual stocks presently in the djia .
we show that this gain / loss asymmetry established for the djia surprisingly is _ not _ present in the time series of the individual stocks .
the most reasonable explanation for this fact is that the gain / loss asymmetry observed in the djia as well as in the sp500 and nasdaq are due to movements in the market as a whole , _
i.e. _ , cooperative cascade processes ( or `` synchronization '' ) which disappear in the inverse statistics of the individual stocks . .
And you have already written the first three sentences of the full article: what drives prices ?
this question has been studied for centuries with quantitative theories dating back at least to bachelier @xcite , who proposed the random walk hypothesis for price trajectories . as prices in general
do not become negative , economist later realized that a more realistic framework was obtained by assuming the random walk hypothesis for the logarithm of the price @xcite ..
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this has made relative returns the prime focus of financial investigation with only a few exceptions , such as hedge funds focusing on absolute returns , and benchmarking are almost exclusively done by the financial community by comparing relative returns with respect to a fixed time interval . within the current economic paradigm
the efficient market hypothesis ( emh ) @xcite the idea of randomly fluctuating prices in the absence of new hard information has been re - formulated in the framework of hard - working rational traders with complete knowledge of all available information whose continuing effort more or less instantaneously removes any imbalance in prices due to past differences in the expectations of traders . in short ,
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Suppose that you have an abstract for a scientific paper: this paper is the first one in a series devoted to the study of the dynamics of the atmospheres of long - period variable ( lpv ) stars .
results from a two - month - long monitoring of the mira variables rtcyg and xoph around maximum light with the elodie spectrograph at the haute - provence observatory are presented .
the monitoring covers phases 0.80 to 1.16 for rtcyg and phases 0.83 to 1.04 for xoph .
the cross - correlation profile of the spectrum of rtcyg with a k0iii mask confirms that the absorption lines of rtcyg in the optical domain appear double around maximum light .
no line doubling was found in the optical spectrum of xoph around maximum light , indicating that this feature is not common to all lpvs .
this paper also presents the application to rtcyg of a new tomographic technique deriving the velocity field across the atmosphere by cross - correlating the optical spectrum with numerical masks constructed from synthetic spectra and probing layers of increasing depths .
this technique reveals that both the temporal evolution of the line doubling , and its variation with depth in the atmosphere of rtcyg , are consistent with the ` scenario ' .
this scenario relates the temporal evolution of the red and blue peaks of the double absorption lines to the progression of a shock wave in the atmosphere . the temporal evolution of the balmer , , and emission lines around maximum light is also presented for rtcyg and xoph .
the velocity variations of and of the absorption lines are discussed in the framework of two competing models for the formation of balmer emission lines in lpv stars . .
And you have already written the first three sentences of the full article: long - period variable stars ( lpvs ) are cool giant stars showing more or less periodic light variations with amplitudes of several magnitudes in the visual and with periods of several hundred days . depending on their visual amplitudes and on the regularity of their variability cycles , they appear in several flavours , namely mira ceti - type variables ( mira stars or miras ) , semi - regular variables ( of the sra or srb subtypes ) or irregular variables ( of the lb subtype ) .
mira and sr variables represent one of the latest stages in the evolution of stars with initial masses in the approximate range 1 to 9 . it is known since long that the brightness variations of lpvs go along with spectral changes : ( i ) hydrogen and some metallic lines turn from absorption to emission after minimum light ( merrill 1921 ) , ( ii ) the velocity of the emission and absorption lines correlates with phase and excitation potential ( merrill 1923a ; adams 1941 ) , ( iii ) several absorption lines appear double around maximum light ( adams 1941 ; merrill & greenstein 1958 ; maehara 1968 ) . in a review on red stars ,
merrill ( 1955 ) was the first to suggest that the bright emission lines sometimes appearing in lpvs may be explained by some kind of `` hot front '' moving outward ..
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he further suggested that this running hot front may have the structure of a shock wave .
although the shock wave scenario is nowadays quite widely accepted ( see de la reza 1986 and references therein ) , the lack of self - consistent pulsation models for lpv stars ( due to the important role played by convection and the difficulty of modelling it ) prevents from grasping exactly how , why and where emission and double absorption lines form . as a consequence , several ( sometimes conflicting ) theories aiming at explaining
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Suppose that you have an abstract for a scientific paper: we want to select the best systems out of a given set of systems ( or rank them ) with respect to their expected performance . the systems allow random observations only and we assume that the joint observation of the systems has a multivariate normal distribution with unknown mean and covariance .
we allow dependent marginal observations as they occur when common random numbers are used for the simulation of the systems .
in particular , we focus on positively dependent observations as they might be expected in heuristic optimization where ` systems ' are different solutions to an optimization problem with common random inputs . in each iteration , we allocate a fixed budget of simulation runs to the solutions .
we use a bayesian setup and allocate the simulation effort according to the posterior covariances of the solutions until the ranking and selection decision is correct with a given high probability . here , the complex posterior distributions are approximated only but we give extensive empirical evidence that the observed error probabilities are well below the given bounds in most cases .
we also use a generalized scheme for the target of the ranking and selection that allows to bound the error probabilities with a bonferroni approach .
our test results show that our procedure uses less simulations than comparable procedures from literature even in most of the cases where the observations are not positively correlated .
* keywords : * sequential ranking and selection , common random numbers , bayesian statistics , multiple testing , missing data .
And you have already written the first three sentences of the full article: we consider ranking and selection of systems based on the average performance of the alternatives .
the particular set - up used here is motivated by problems from optimization under uncertainty .
often in operations research as well as in technical applications the performance of solutions depends on some random influence like market conditions , material quality , or simply measurement errors . we shall call such random influences a random _ scenario_. usually , the aim is then to find a solution with minimal expected costs taken over all scenarios ..
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we assume here that we can describe the random scenario mathematically by a random variable @xmath0 with a distribution @xmath1 .
let @xmath2 denote the cost of solution @xmath3 if it has been applied to random scenario @xmath4 then the average costs are given by the expectation @xmath5 . except for particularly simple cases , we will not be able to calculate this expression analytically . instead , we have to estimate @xmath5 based on a sample @xmath6 where @xmath7 are observations of the random variable @xmath8 , usually produced by a stochastic simulation model on a computer . with estimated costs , optimization can be performed by heuristic search methods like genetic algorithms or ant algorithms .
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Suppose that you have an abstract for a scientific paper: an original method to exactly solve the non - markovian master equation describing the interaction of a single harmonic oscillator with a quantum environment in the weak coupling limit is reported . by using a superoperatorial approach we succeed in deriving the operatorial solution for the density matrix of the system .
our method is independent of the physical properties of the environment .
we show the usefulness of our solution deriving explicit expressions for the dissipative time evolution of some observables of physical interest for the system , such as , for example , its mean energy . .
And you have already written the first three sentences of the full article: the problem of the quantum dynamics of a small system interacting with its environment has been extensively studied since the origin of quantum mechanics . however , in spite of the noticeable progresses in the theory of open quantum systems , many conceptual difficulties still remain . indeed
the understanding of the effects of the environment on the physical system of interest , in general , is not an easy task .
the conventional way to afford the problem of the description of the time evolution of an open quantum system consists in eliminating the degrees of freedom of the environment in order to derive an equation of motion for the reduced density matrix of the small system ..
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this procedure stems from the fact that we are usually only interested in the dynamics of this subsystem and do not really care about the state of the environment and its evolution .
the procedure of tracing over the environmental variables thus amounts at declaring that everything other than the small system is indifferent to us . in this way one reduces the number of variables one needs to take into account to study the problem .
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Suppose that you have an abstract for a scientific paper: the first ibis galactic plane survey has provided a list of high energy emitting objects above 20 kev ; these sources have been detected mostly in the crowded region of the galactic centre and partly along the galactic plane . in order to validate the detection procedure , to help in the identification process and to study the nature of these ibis sources ,
this list has been cross correlated with the data archive of the pds instrument on bepposax , which operated in a similar energy band and with a similar sensitivity .
we discover a number of associations whose detailed analysis will be particularly useful for the survey work .
also , thanks to the imaging capability of ibis / isgri , objects which could not be studied by the pds due to contamination from nearby sources can now be associated with a definite source or sources .
[ 2001/04/25 1.1 ( pwd ) ] .
And you have already written the first three sentences of the full article: the ibis / isgri survey ( bird et al . 2004 ) contains 123 high energy emitting objects detected with the unprecedented sensitivity of @xmath01 mcrab in the energy range 20 - 100 kev discovered by mosaicing all core program observations performed in the first year of the mission ; this first catalogue contains 23 high mass and 53 low mass binary systems , 5 agn , a few snr / x - ray pulsar systems , a few isolated pulsars and a handful of other objects .
around 30 remain at the moment unidentified and are the main targets of follow up observations .
observations of these and other sources in the ibis survey at x - ray wavelengths are useful in order to assess their nature and overall characteristics ; in this sense the bepposax / pds archive is a powerful tool as it can provide information on any spectral and/or flux variation provided that the pds observation was not contaminated by nearby sources . to this end , we have started a program to analyse all pds observations which contain in the field of view a source detected by ibis : the systematic search of the archive has provided a set of 68 objects which were targets of bepposax observations and so have both mecs / pds ( 2 - 100 kev band ) data . in this case.
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it is possible to reconsider the pds data in the light of the ibis images in order to exclude or evaluate any contamination present .
the pds field of view is 1.3@xmath1 ( fwhm ) , hexagonal in shape and with no imaging capability ( frontera et al .
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Suppose that you have an abstract for a scientific paper: the effect of color superconductivity on the cooling of quark stars and neutron stars with large quark cores is investigated .
various known and new quark - neutrino processes are studied . as a result , stars being in the color flavor locked ( cfl ) color superconducting phase cool down extremely fast .
quark stars with no crust cool down too rapidly in disagreement with x - ray data .
the cooling of stars being in the @xmath0 color superconducting ( 2sc ) phase with a crust is compatible with existing x - ray data .
also the cooling history of stars with hypothetic pion condensate nuclei and a crust does not contradict the data . .
And you have already written the first three sentences of the full article: the interiors of compact stars have been discussed as systems where high - density phases of strongly interacting matter do occur in nature , see @xcite and @xcite .
the consequences of different phase transition scenarios for the cooling behaviour of compact stars have been reviewed recently @xcite in comparison with existing x - ray data .
a particular discussion has been devoted to the idea that a strong attraction in three flavor @xmath1-quark matter may allow for the existence of super - dense anomalous nuclei and strange quark stars @xcite ..
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thereby , in dependence on the value of the bag constant @xmath2 different possible types of stars were discussed : ordinary neutron stars ( ns ) without any quark core , neutron stars with quark matter present only in their deep interiors ( for somewhat intermediate values of @xmath2 ) , neutron stars with a large quark core ( qcns ) and a crust typical for neutron stars , and quark stars ( qs ) with a tiny crust of normal matter and with no crust ( both for low @xmath2 values ) . by qcns
we understand compact stars in which the hadronic shell is rather narrow in the sense that it does not essentially affect the cooling which is mainly due to the quark core .
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Suppose that you have an abstract for a scientific paper: the wmap satellite , devoted to the observations of the anisotropies of the cosmic microwave background ( cmb ) radiation , has recently provided a determination of the baryonic density of the universe with unprecedented precision . using this ,
big bang nucleosynthesis ( bbn ) calculations predict a primordial @xmath0li abundance which is a factor @xmath1 higher than that observed in galactic halo dwarf stars . it has been argued that this discrepancy could be resolved if the @xmath2be(d , p)2@xmath3 reaction rate is around a factor of 100 larger than has previously been considered .
we have now studied this reaction , for the first time at energies appropriate to the big bang environment , at the cyclone radioactive beam facility at louvain - la - neuve .
the cross section was found to be a factor of 10 _ smaller _ than derived from earlier measurements .
it is concluded therefore that nuclear uncertainties can not explain the discrepancy between observed and predicted primordial @xmath0li abundances , and an alternative astrophysical solution must be investigated . .
And you have already written the first three sentences of the full article: using the wmap - determination of the baryonic density @xcite , one obtains predictions of the abundances of the light element isotopes produced in big bang nucleosynthesis @xcite . while the overall values from theoretical predictions and from the observational determinations of the abundances of d and @xmath4he are in good agreement , the theory tends to predict a higher @xmath0li abundance ( by a factor 2 to 3 ) than is observed in the atmospheres of halo dwarf stars @xcite .
the nacre compilation @xcite provided a new set of reaction rates that were used to update the predictions of contemporary big bang nucleosynthesis ( bbn ) @xcite . at that time , the baryonic densities obtained from cmb observations on the one hand and comparison between bbn calculations and spectroscopic data on the other hand were only marginally compatible @xcite . in order to improve the nuclear network ,
@xcite recently performed a re - analysis of low energy data from the 10 key nuclear reactions involved in bbn , by using r - matrix theory @xcite and evaluating the remaining uncertainties in a statistically robust formalism . using this improved network ,.
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@xcite have recently calculated bbn light element productions assuming for the baryonic density the very precise value provided by wmap @xcite and obtained @xmath2li / h@xmath5 compared to the observed value li / h @xmath6 , confirming the @xmath2li discrepancy .
however , it has been shown @xcite that the @xmath2be(d , p)2@xmath3 reaction ( which destroys the @xmath2be that is the source of @xmath2li at high baryonic density ) , would solve the @xmath2li problem _ if _ its cross section were much higher than assumed .
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Suppose that you have an abstract for a scientific paper: abstract after a brief review of spin networks and their interpretation as wave functions for the ( space ) geometry , we discuss the renormalisation of the area operator in loop quantum gravity .
in such a background independent framework , we propose to probe the structure of a surface through the analysis of the coarse - graining and renormalisation flow(s ) of its area .
we further introduce a procedure to coarse - grain spin network states and we quantitatively study the decrease in the number of degrees of freedom during this process .
finally , we use these coarse - graining tools to define the correlation and entanglement between parts of a spin network and discuss their potential interpretation as a natural measure of distance in such a state of quantum geometry . .
And you have already written the first three sentences of the full article: loop quantum gravity ( lqg ) proposes a background independent framework for a theory of quantum general relativity @xcite .
it realizes a canonical quantization of general relativity in 3 + 1 space - time dimensions and defines the hilbert space of quantum states of 3d space geometry and their dynamics ( through a hamiltonian constraint ) .
background independence means that there is no assumed background metric at all and that the quantum state of geometry describes the whole metric of space(-time ) and not simply the perturbations of the metric field around a fixed background metric ..
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the whole geometry of the space(-time ) needs to be reconstructed from the quantum state : all geometric notions , such as the distance , need to be constructed from scratch since you can not rely on a background geometry to define , for instance , a reference notion of distance that you could use to describe the metric perturbations .
the states of 3d space geometry are ( superpositions ) of spin networks .
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Suppose that you have an abstract for a scientific paper: most stars reside in binary / multiple star systems ; however , previous models of planet formation have studied growth of bodies orbiting an isolated single star . disk material has been observed around both components of some young close binary star systems .
additionally , it has been shown that if planets form at the right places within such disks , they can remain dynamically stable for very long times .
herein , we numerically simulate the late stages of terrestrial planet growth in circumbinary disks around ` close ' binary star systems with stellar separations 0.05 au @xmath0 0.4 au and binary eccentricities 0 @xmath1 0.8 . in each simulation ,
the sum of the masses of the two stars is 1 m@xmath2 , and giant planets are included .
the initial disk of planetary embryos is the same as that used for simulating the late stages of terrestrial planet formation within our solar system by chambers ( 2001 , making more terrestrial planets , icarus 152 , 205 - 224 ) , and around each individual component of the @xmath3 centauri ab binary star system by quintana et al .
( 2002 , terrestrial planet formation in the @xmath3 centauri system , astrophys .
j. 576 , 982 - 996 ) .
multiple simulations are performed for each binary star system under study , and our results are statistically compared to a set of planet formation simulations in the sun - jupiter - saturn system that begin with essentially the same initial disk of protoplanets .
the planetary systems formed around binaries with apastron distances @xmath4
@xmath5 @xmath6(1 + @xmath7 ) @xmath8 0.2 au are very similar to those around single stars , whereas those with larger maximum separations tend to be sparcer , with fewer planets , especially interior to 1 au .
we also provide formulae that can be used to scale results of planetary accretion simulations to various systems with different total stellar mass , disk sizes , and planetesimal masses and densities . _
keywords : _ planetary formation ; terrestrial planets ; extrasolar planets .
And you have already written the first three sentences of the full article: more than half of all main sequence stars , and an even larger fraction of pre - main sequence stars , are in binary / multiple star systems ( duquennoy and mayor 1991 ; mathieu et al .
virtually all previous models of planet formation , however , have assumed an isolated single star . of the first 131 extrasolar planet systems that have been confirmed , at least 30 are on so - called s - type orbits that encircle one component of a binary star system , including at least 3 that orbit one member of a triple - star system ( raghavan et al .
the effect of the stellar companion on the formation of these planets , however , remains unclear ..
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one planet has been detected in a p - type orbit which encircles both members of a binary star system .
this planet , which has a minimum mass of @xmath9 2.5 times the mass of jupiter ( m@xmath10 ) , orbits @xmath9 23 au from the center of mass of psr 1620 - 26 , a radio pulsar binary comprised of a neutron star and a white dwarf in a @xmath9 191 day stellar orbit ( lyne et al .
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Suppose that you have an abstract for a scientific paper: accurate and useful analytic approximations are developed for order parameter profiles and interfacial tensions of phase - separated binary mixtures of bose - einstein condensates .
the pure condensates 1 and 2 , each of which contains a particular species of atoms , feature healing lengths @xmath0 and @xmath1 .
the inter - atomic interactions are repulsive .
in particular , the effective inter - species repulsive interaction strength is @xmath2 . a triple - parabola approximation ( tpa )
is proposed , to represent closely the energy density featured in gross - pitaevskii ( gp ) theory .
this tpa allows us to define a model , which is a handy alternative to the full gp theory , while still possessing a simple analytic solution .
the tpa offers a significant improvement over the recently introduced double - parabola approximation ( dpa ) . in particular , a more accurate amplitude for the wall energy ( of a single condensate ) is derived and , importantly , a more correct expression for the interfacial tension ( of two condensates ) is obtained , which describes better its dependence on @xmath2 in the strong segregation regime , while also the interface profiles undergo a qualitative improvement . .
And you have already written the first three sentences of the full article: at ultralow temperature phase separation of quantum gases has been realized experimentally , in particular in binary mixtures of bose - einstein condensates ( becs ) . for a survey ,
see , e.g. , refs .
early theoretical studies on trapped multicomponent becs @xcite appeared at the same time as experiments that witnessed weakly segregated dual becs @xcite ..
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ten more years were necessary to observe bec components that are strongly segregated @xcite but by now these are commonly studied experimentally @xcite by use of becs with different spin states , isotopes and species .
these experiments also revived the theoretical interest , much of which is focused on physical phenomena where the interface , separating the bec components , plays a key role .
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Suppose that you have an abstract for a scientific paper: in the absence of an astrophysical standard candle , icecube can study the deficit of cosmic rays from the direction of the moon .
the observation of this `` moon shadow '' in the downgoing muon flux is an experimental verification of the absolute pointing accuracy and the angular resolution of the detector with respect to energetic muons passing through .
the moon shadow has been observed in the 40-string configuration of icecube .
this is the first stage of icecube in which a moon shadow analysis has been successful .
method , results , and some systematic error studies will be discussed .
icecube , moon shadow , pointing capability .
And you have already written the first three sentences of the full article: icecube is a kilometer - cube scale cherenkov detector at the geographical south pole , designed to search for muons from high energy neutrino interactions .
the arrival directions and energy information of these muons can be used to search for point sources of astrophysical neutrinos , one of the primary goals of icecube .
the main component of icecube is an array of optical sensors deployed in the glacial ice at depths between 1450 m and 2450 m. these digital optical modules ( doms ) , each containing a 25 cm diameter photomultiplier tube with accompanying electronics within a pressure housing , are lowered into the ice along `` strings . ''.
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there are currently 59 strings deployed of 86 planned ; the data analyzed here were taken in a 40 string configuration , which was in operation between april 2008 and april 2009 .
there are 13 lunar months of data within that time . in this analysis we present results from 8 lunar months of the 40 string configuration . for a muon with energy on the order of a tev
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Suppose that you have an abstract for a scientific paper: plus 1pt minus 1pt0.3 cm this is the first of two lectures on the technique of dimensional continuation employed by brown , preston , and singleton ( bps ) to calculate such quantities as the charged particle stopping power and the temperature equilibration rate in a plasma . in this exposition
we will examine some of the more basic points of dimensional continuation , with an emphasis on the coulomb logarithm for electron - ion temperature equilibration .
dimensional continuation , or dimensional regularization as it is more properly known in quantum field theory , was originally developed as part of the renormalization procedure for the theories of the electroweak and other fundamental interactions in particle physics .
dimensional continuation is so general , in fact , that any _ theory _ can be unambiguously lifted to dimensions beyond three , and therefore the technique is powerful enough to apply in many other settings .
the technique , however , is not well known outside the field theory and particle physics communities .
this exposition will therefore be self - contained , intended for those who are not specialists in quantum field theory , and i will either derive or motivate any requisite field theory results or concepts . of particular relevance is the analogy between the coulomb logarithm as calculated by lyman spitzer on the one hand , and the lamb shift as calculated by hans bethe on the other . while dimensional continuation is a well developed and a thoroughly tested method for regularizing any quantum field theory ,
bps employs the method in a novel way that provides the leading and subleading behavior for processes that involve competing disparate energy or length scales .
in particular , bps calculated the temperature equilibration rate to leading and next - to - leading order in the plasma number density for any two species in a plasma that are in thermal equilibrium with themselves , but not necessarily with each other .
no restriction is made on the charge , mass ,....
And you have already written the first three sentences of the full article: this is the first of two lectures on a new technique for calculating the temperature equilibration rate between electrons and ions in a weakly to moderately coupled fully - ionized plasma , exact to leading and next - to - leading order in the plasma number density .
this calculation was first performed in section 12 of ref .
@xcite , a work whose primary focus was the charged particle stopping power in a plasma ..
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this paper assumed familiarity with a number of field theory concepts , and section 12 relied heavily on the charged particle stopping power results derived in previous sections of that work .
in contrast , these lectures will be self - contained .
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Suppose that you have an abstract for a scientific paper: the electromagnetic transition form factors of @xmath0 and @xmath1 are calculated in the light - cone perturbation theory .
we show that it is unreliable to determine the -mixing angle without any additional normalization conditions other than their decay widthes to two photons .
the possible intrinsic @xmath2 component in the flavor singlet is investigated .
the heavy quark pair has distinct properties from the light ones in electromagnetic transition processes of pseudoscalar mesons .
it is possible to explore the size of @xmath2 component and our numerical results disfavor a large portion of @xmath2 component . /#1#1/
# 1#1/ .
And you have already written the first three sentences of the full article: the recent cleo experiments related with and supply possibilities to extract the information about the structures of these two pseudoscalar mesons . for example , the cleo collaboration @xcite has reported very large branching ratios for inclusive production @xmath3 and for the exclusive decay @xmath4 @xmath5 to explain the abnormally large production of in the standard model , either large portion of intrinsic @xmath6 component in @xcite or large coupling of to @xmath7 @xcite , even both of them , must be concluded . at the same time , the data of the @xmath8 , @xmath9 and @xmath10 transition form factors at higher energies reported by cleo @xcite suggest that may have very different non - perturbative properties from @xmath11 and , while the latter two have similar wave functions .
it is reasonable because the physical and states consist dominantly of flavor su(3 ) octet @xmath12 and singlet @xmath13 , respectively .
the usual mixing scheme reads [ mixing ] latexmath:[\ ] ] from the bhl model ..
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the transition form factor of su(3 ) singlet or octet is @xmath92 where @xmath93 or 8 presents the singlet or octet .
the charge factors are @xmath94 , @xmath95 , @xmath96 , @xmath97 , @xmath98 , and @xmath99 .
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Suppose that you have an abstract for a scientific paper: we address the question of when cluster - tilted algebras of dynkin type @xmath0 are derived equivalent and as main result obtain a complete derived equivalence classification .
it turns out that two cluster - tilted algebras of type @xmath0 are derived equivalent if and only if their cartan matrices represent equivalent bilinear forms over the integers which in turn happens if and only if the two algebras are connected by a sequence of `` good '' mutations . for type @xmath1
all details are given in the paper , for types @xmath2 and @xmath3 we present the results in a concise form from which our findings should easily be verifiable .
derived equivalence classification of cluster - tilted algebras of dynkin type @xmath0 janine bastian@xmath4 , thorsten holm@xmath4 , and sefi ladkani@xmath5 @xmath4 leibniz universitt hannover , institut fr algebra , zahlentheorie und diskrete mathematik , welfengarten 1 , d-30167 hannover , germany + bastian,[email protected] @xmath5 max - planck - institut fr mathematik , vivatsgasse 7 , d-53111 bonn , germany + .
And you have already written the first three sentences of the full article: cluster algebras have been introduced by fomin and zelevinsky around 2000 and have enjoyed a remarkable success story in recent years .
they attractively link various areas of mathematics , like combinatorics , algebraic lie theory , representation theory , algebraic geometry and integrable systems and have applications to mathematical physics . in an attempt to categorify cluster algebras ( without coefficients ) , cluster categories have been introduced by buan , marsh , reiten , reineke , todorov @xcite .
more precisely , these are orbit categories of the form @xmath6 $ ] where @xmath7 is a quiver without oriented cycles , @xmath8 is the bounded derived category of the path algebra @xmath9 ( over an algebraically closed field @xmath10 ) and @xmath11 and @xmath12 $ ] are the auslander - reiten translation and shift functor on @xmath8 , respectively ..
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remarkably , these cluster categories are again triangulated categories by a result of keller @xcite .
quivers of dynkin types @xmath13 play a special role in the theory of cluster algebras since they parametrize cluster - finite cluster algebras , by a seminal result of fomin and zelevinsky @xcite .
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Suppose that you have an abstract for a scientific paper: we present models that reproduce the observed double - shell structure of the homunculus nebula around @xmath0 carinae , including the stratification of infrared h@xmath1 and [ fe ii ] emission seen in data obtained with the phoenix spectrograph on gemini south , as well as the corresponding stratified grain temperature seen in thermal - infrared data .
tuning the model to match the observed shell thickness allows us to determine the threshold density which permits survival of h@xmath1 .
an average density of @xmath2(0.51)@xmath310@xmath4 @xmath5 in the outer zone is required to allow h@xmath1 to exist at all latitudes in the nebula , and for fe@xmath6 to recombine to fe@xmath7 .
this gives independent confirmation of the very large mass of the homunculus , indicating a total of roughly 1535 m@xmath8 ( although we note reasons why the lower end of this range is favored ) . at the interface between the atomic and molecular zones , we predict a sharp drop in the dust temperature , in agreement with the bimodal dust color temperatures observed in the two zones . in the outer molecular shell
, the dust temperature drops to nearly the blackbody temperature , and becomes independent of grain size because of self - shielding at shorter uv wavelengths and increased heating at longer wavelengths .
this relaxes constraints on large grain sizes suggested by near - blackbody color temperatures .
finally , from the strength of infrared [ fe ii ] emission in the inner shell we find that the gas - phase fe abundance is roughly solar .
this is astonishing in such a dusty object , where one normally expects gaseous iron to be depleted by two orders of magnitude . .
And you have already written the first three sentences of the full article: the bipolar homunculus nebula surrounding @xmath0 carinae offers an unusually well - constrained laboratory to study a wide array of physical processes in the interstellar medium .
the distance , size , shape , orientation , and structure of the nebula are all known ( smith 2006 ; davidson et al .
2001 ) , as are its expansion velocity and age ( morse et al . 2001 ; currie & dowling 1999 ; smith & gehrz 1998 ) ..
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ionized ejecta outside the homunculus indicate nitrogen - rich gas ( davidson et al . 1986
; dufour et al . 1997 ; smith & morse 2004 ) , and the recent detection of ammonia in the homunculus suggests that it too is n - rich ( smith et al .
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Suppose that you have an abstract for a scientific paper: we use some of the largest order statistics of the random projections of a reference signal to construct a binary embedding that is adapted to signals correlated with such signal .
the embedding is characterized from the analytical standpoint and shown to provide improved performance on tasks such as classification in a reduced - dimensionality space .
binary embeddings , random projections .
And you have already written the first three sentences of the full article: the ever - increasing amount of information that is produced in the age of big data calls for efficient techniques for storage and processing of a large number of high - dimensional signals .
compact representations can be obtained with different methods depending whether the particular task requires signal reconstruction ( e.g. , image and video compression for delivery and visualization ) or the goal is to infer some information from the signals ( e.g. , in classification , regression , information retrieval , etc . ) .
embeddings provide compact representations of signals for the latter tasks ..
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formally , an embedding is a transformation that maps a set of signals in a high dimensional space to a lower dimensional space , in such a way that the geometry of the set is approximately preserved .
the concept of embedding has been successfully used in the context of information retrieval @xcite , where it is usually called `` hashing '' .
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Suppose that you have an abstract for a scientific paper: the monoidal category of soergel bimodules can be thought of as a categorification of the hecke algebra of a finite weyl group .
we present this category , when the weyl group is the symmetric group , in the language of planar diagrams with local generators and local defining relations . .
And you have already written the first three sentences of the full article: in the paper @xcite soergel gave a combinatorial description of a certain category of harish - chandra bimodules over a simple lie algebra @xmath0 .
this category was and continues to be of primary interest in the infinite - dimensional representation theory of simple lie algebras .
soergel described the category anew as a full subcategory of bimodules over a certain ring @xmath1 . the objects in this subcategory are now commonly called soergel bimodules ..
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the category of soergel bimodules is additive and monoidal , and soergel constructed an isomorphism between the grothendieck ring of his category and the integral form of the hecke algebra of the weyl group @xmath2 of @xmath0 .
hence , soergel s construction provides a categorification of the hecke algebra .
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Suppose that you have an abstract for a scientific paper: the effect of static electromagnetic fields on the propagation of light is analyzed in the context of a particular class of scalar - tensor gravitational theories .
it is found that for appropriate field configurations and light polarization , anomalous amplitude variations of the light as it propagates in either a magnetized or electrified vacuum are strong enough to be detectable in relatively simple laboratory experiments . .
And you have already written the first three sentences of the full article: scalar - tensor ( st ) gravitational theories are the most firm candidates for extensions of general relativity ( gr ) .
a great part of their interest comes from the fact that they are induced naturally in the reduction to four dimensions of string and kaluza - klein models@xcite , resulting mostly in the form of a brans - dicke ( bd ) type of st theorybransdicke , often involving also non - minimal coupling to matter , leading to the so called fifth force@xcite .
it is also interesting that st theories are shown to be mathematically equivalent to theories with action depending non - linearly on the ricci scalar , the so called @xmath0 theories@xcite ..
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finally , st theories are possibly the simplest extension of gr that could accommodate cosmological issues as inflation and universe - expansion acceleration , as well as possible space - time variation of fundamental constants@xcite . on the other hand , observational and experimental
evidence puts strong limits to the observable effects of a possible scalar field .
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Suppose that you have an abstract for a scientific paper: narrow - band @xmath0 wfpc2 images reveal a bow - shock - like halo around the region n30b toward the b[e ] supergiant hen s22 located within the larger deml106 nebula in the large magellanic cloud .
high - dispersion spectra of n30b show a narrow h@xmath1 emission component from the ionized gas ; the velocity variations indicate a gas flow of @xmath25 to @xmath210 km s@xmath3 in the vicinity of the regions , which is resultant from interactions with hen s22 s stellar wind and responsible for the bow - shock morphology .
spectra of n30b s halo show broad h@xmath1 profiles extending over @xmath4 km s@xmath3 , similar to that of hen s22 , indicating that the halo is a reflection nebula of hen s22 .
broad - band morphologies of n30b s halo are also consistent with the reflection nebula interpretation
. we use dust - scattering properties and the observed brightnesses of the reflection nebula and hen s22 to constrain the reflection geometry .
the reflected stellar h@xmath1 emission and absorption vary across the reflection nebula as a result of viewing s22 s anisotropic wind across varying angles .
this reflection nebula , together with the edge - on orientation of hen s22 s disk , provides an invaluable opportunity to study the disk and polar winds of a b[e ] supergiant . .
And you have already written the first three sentences of the full article: a _ hubble space telescope ( hst ) _ wfpc2 h@xmath1 image of the region deml106
@xcite in the large magellanic cloud ( lmc ) revealed a pair of bright , compact regions embedded within a large shell nebula @xcite .
deml106 has been previously cataloged by @xcite as n30 , and the two compact regions were identified as an knot and designated as n30b . as shown in figure 1 , while the main body of n30b is unremarkable , it is surrounded by a halo with sharp edges on the northern rim facing the luminous b[e ] supergiant hen s22.
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(= hd34664 ; * ? ? ?
b[e ] supergiants are known to possess stellar winds @xcite .
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Suppose that you have an abstract for a scientific paper: in the effort to obtain low cost routine space debris observations in low earth orbit , esa plans to utilise the radar facilities of the european incoherent scatter scientific association .
first demonstration measurements were performed from 11 to 23 february 2001 . in total
@xmath0 of radar signals were collected .
here we compare these initial measurements with the predictions of the esa master / proof99 model in order to assess the sensitivity as well as the reliability of the data .
we find that while the determination of object size needs to be reviewed , the altitude distribution provides a good fit to the model prediction .
the absolute number of objects detected in the various altitude bins indicates that the coherent integration method indeed increases the detection sensitivity when compared to incoherent integration . in the data presented here integration times from @xmath1 to @xmath2
were used .
as expected , orbit information can not be obtained from the measurements if they are linked to ionospheric measurements as planned .
in addition routine space debris observations provide also useful information for the validation of large - object catalogues .
( 0,0)(0,0 ) ( -50,180)pedas1-b1.4 - 0003 - 02 .
And you have already written the first three sentences of the full article: currently esa monitors the space debris population in low earth orbit ( leo ) in irregular intervals @xcite .
this is done in the frame of 24 hour radar beam - park experiments .
the data from these measurements are taken in order to constrain models of the population evolution of space debris in orbit @xcite ..
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the most prominent of the european space debris models is master / proof99 , which allows spacecraft operators to assess the risk of a debris impact for their mission .
as the 24 hour experiments only provide a snapshot of the environment , the temporal behaviour of the space debris population is difficult to determine .
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Suppose that you have an abstract for a scientific paper: based on the asymptotic analysis of ordinary differential equations , we classify all spherically symmetric self - similar solutions to the einstein equations which are asymptotically friedmann at large distances and contain a perfect fluid with equation of state @xmath0 with @xmath1 .
this corresponds to a `` dark energy '' fluid and the friedmann solution is accelerated in this case due to anti - gravity .
this extends the previous analysis of spherically symmetric self - similar solutions for fluids with positive pressure ( @xmath2 ) .
however , in the latter case there is an additional parameter associated with the weak discontinuity at the sonic point and the solutions are only asymptotically `` quasi - friedmann '' , in the sense that they exhibit an angle deficit at large distances . in the @xmath1 case
, there is no sonic point and there exists a one - parameter family of solutions which are _ genuinely _ asymptotically friedmann at large distances .
we find eight classes of asymptotic behavior : friedmann or quasi - friedmann or quasi - static or constant - velocity at large distances , quasi - friedmann or positive - mass singular or negative - mass singular at small distances , and quasi - kantowski - sachs at intermediate distances .
the self - similar asymptotically quasi - static and quasi - kantowski - sachs solutions are analytically extendible and of great cosmological interest .
we also investigate their conformal diagrams .
the results of the present analysis are utilized in an accompanying paper to obtain and physically interpret numerical solutions . .
And you have already written the first three sentences of the full article: there is great interest in spherically symmetric self - similar solutions to einstein s equations because of their numerous applications in astrophysics and cosmology @xcite .
indeed there is now considerable evidence for the similarity hypothesis , which postulates that spherically symmetric solutions may naturally evolve to self - similar form in a variety of situations .
the status of this hypothesis has been recently reviewed by carr and coley @xcite . in view of this.
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, it is clearly important to have as complete a classification of spherically symmetric self - similar solutions as possible .
spherically symmetric self - similar solutions have the feature that all dimensionless quantities can be expressed in terms of @xmath3 , where @xmath4 and @xmath5 are suitably chosen radial and time coordinates .
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Suppose that you have an abstract for a scientific paper: we report results of our search for fast oscillations in lightcurve of one of the brightest accretion powered pulsars on the sky v0332 + 53 with the help of data of the pca spectrometer of the rxte observatory .
in course of this search we have carefully explored complications appearing if one uses only sub - bands of the total bandpass of the pca spectrometer .
we show that lightcurves collected in the soft sub - band of the pca spectrometer contains an additional instrumental noise , lightcurves of harder sub - bands lack some fraction of the anticipated poisson noise .
we show that this noise is caused by a cross - talk of energy bands , which lasts up to @xmath0sec .
one hypothesis is that these effects are caused by temporarily drop of the pca detector gain after any occurred event due to slowly moving ions in the detector volume . in order to avoid this effect we searched for fast oscillations in flux of v0332 + 53 only in the total bandpass of the pca spectrometer 2 - 60 kev .
we have not detected any quasi - periodic oscillations in lightcurve of the source with an upper limit at the level of 0.5% in the fourier frequency range 200 - 1500 hz .
[ firstpage ] accretion , accretion discs , x - rays : binaries stars : individual : sco x-1 stars : individual : v0332 + 53 .
And you have already written the first three sentences of the full article: binary systems with a compact object are among the brightest sources in galaxies , in particular in the x - ray energy range . their bolometric luminosity is powered by accretion onto relativistic objects like neutron star ( ns ) or black hole ( bh ) .
luminosity of black hole accretors is produced by accretion disks @xcite , while neutron star accretors have additional structures on their surfaces . in case of non
magnetic neutron stars it is a boundary / spreading layer , in which rapidly rotating matter of the accretion disk decelerate to neutron star rotational velocity ( e.g. * ? ? ?.
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* ; * ? ? ?
* ; * ? ? ?
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Suppose that you have an abstract for a scientific paper: using the very long base array , we observed the young stellar object ec 95 in the serpens cloud core at eight epochs from december 2007 to december 2009 .
two sources are detected in our field , and are shown to form a tight binary system .
the primary ( ec 95a ) is a 45 @xmath0 proto - herbig aebe object ( arguably the youngest such object known ) , whereas the secondary ( ec 95b ) is most likely a low - mass t tauri star .
interestingly , both sources are non - thermal emitters .
while t tauri stars are expected to power a corona because they are convective while they go down the hayashi track , intermediate - mass stars approach the main sequence on radiative tracks .
thus , they are not expected to have strong superficial magnetic fields , and should not be magnetically active .
we review several mechanisms that could produce the non - thermal emission of ec 95a , and argue that the observed properties of ec 95a might be most readily interpreted if it possessed a corona powered by a rotation - driven convective layer . using our observations
, we show that the trigonometric parallax of ec 95 is @xmath1 = 2.41 @xmath2 0.02 mas , corresponding to a distance of 414.9@xmath3 pc .
we argue that this implies a distance to the serpens core of 415 @xmath2 5 pc , and a mean distance to the serpens cloud of 415 @xmath2 25 pc .
this value is significantly larger than previous estimates ( @xmath4 @xmath5 260 pc ) based on measurements of the extinction suffered by stars in the direction of serpens .
a possible explanation for this discrepancy is that these previous observations picked out foreground dust clouds associated with the aquila rift system rather than serpens itself . .
And you have already written the first three sentences of the full article: an accurate knowledge of the physical properties of young stellar objects ( like their mass , age and luminosity ) is important to constrain theoretical pre main sequence evolutionary models . the determination of these properties , however , depends critically on the availability of accurate distances .
unfortunately , since distances to regions of star formation are often uncertain by more than 20 or 30% , errors on the luminosity and age of young stars are typically about 70% .
significant progress has been possible in recent years thanks to very long baseline interferometry ( vlbi ) observations , particularly with the very long base array ( vlba loinard et al ..
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2005 , 2007 , 2008 ; torres et al . 2007 , 2009 ;
menten et al . 2007 ; xu et al .
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Suppose that you have an abstract for a scientific paper: stochastic dynamical systems arise as models for fluid particle motion in geophysical flows with random velocity fields .
escape probability ( from a fluid domain ) and mean residence time ( in a fluid domain ) quantify fluid transport between flow regimes of different characteristic motion .
we consider a quasigeostrophic meandering jet model with random perturbations .
this jet is parameterized by the parameter @xmath0 , where @xmath1 is the rotation rate of the earth , @xmath2 the earth s radius and @xmath3 the latitude .
note that @xmath1 and @xmath2 are fixed , so @xmath4 is a monotonic decreasing function of the latitude .
the unperturbed jet ( for @xmath5 ) consists of a basic flow with attached eddies . with random perturbations ,
there is fluid exchange between regimes of different characteristic motion .
we quantify the exchange by escape probability and mean residence time .
for an eddy , the average escape probability for fluid particles ( initially inside the eddy ) escape into the exterior retrograde region is smaller than escape into the jet core for @xmath6 , while for @xmath7 , the opposite holds . for a unit jet core near the jet troughs
, the average escape probability for fluid particles ( initially inside the jet core ) escape into the northern recirculating region is greater than escape into the southern recirculating region for @xmath8 , while for @xmath9 , the opposite holds .
moreover , for @xmath10 , fluid particles are about equally likely to escape into either recirculating regions .
furthermore , for a unit jet core near the jet crests , the situation is the opposite as for near the jet troughs .
the maximal mean residence time of fluid particles initially in an eddy increases as @xmath4 increases from @xmath11 to @xmath12 ( or as latitude decreases accordingly ) , then decreases as @xmath4 increases from @xmath12 to @xmath13 ( or as latitude decreases accordingly ) .
however , the maximal mean residence time of fluid particles initially in a....
And you have already written the first three sentences of the full article: stochastic dynamical systems are used as models for various scientific and engineering problems .
we consider the following class of stochastic dynamical systems @xmath15 where @xmath16 are two real independent wiener processes ( white noises ) and @xmath17 are given deterministic functions .
more complicated stochastic systems also occur in applications ( @xcite , @xcite , @xcite ) , @xcite , @xcite , @xcite ) . for.
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a planar bounded domain @xmath18 , we can consider the exit problem of random solution trajectories of ( [ eqn1])-([eqn2 ] ) from @xmath18 . to this end , let @xmath19 denote the boundary of @xmath18 and let @xmath20 be a part of the boundary @xmath19 .
the escape probability @xmath21 is the probability that the trajectory of a particle starting at @xmath22 in @xmath18 first hits @xmath19 ( or escapes from @xmath18 ) at some point in @xmath20 , and @xmath21 is known to satisfy ( @xcite , @xcite and references therein ) @xmath23 suppose that initial conditions ( or initial particles ) are uniformly distributed over @xmath18 .
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Suppose that you have an abstract for a scientific paper: we revisit the image charge method for the green s function problem of the poisson - boltzmann equation for a dielectric sphere immersed in ionic solutions . using finite mellin transformation ,
we represent the reaction potential due to a source charge inside the sphere in terms of one dimensional distribution of image charges .
the image charges are generically composed of a point image at the kelvin point and a line image extending from the kelvin point to infinity with an oscillatory line charge strength .
we further develop an efficient and accurate algorithm for discretization of the line image using pad approximation and finite fraction expansion .
finally we illustrate the power of our method by applying it in a multiscale reaction - field monte carlo simulation of monovalent electrolytes .
poisson - boltzmann equation , finite mellin transform , green s function , multiscale reaction field model , fast algorithm , pad approximation , finite fraction expansion 35j08 ; 65r10 ; 78a35 ; 82d15 .
And you have already written the first three sentences of the full article: the method of image charges is a classical technique @xcite for electrostatic problems .
its most elementary application is the problem of a point charge in a spherical cavity inside a conducting medium ( or the reciprocal problem of a point charge outside a conducting sphere ) . in 1845 , william thomson ( lord kelvin ) @xcite noticed that the vanishing - potential boundary condition of conductors can be automatically satisfied on the sphere by putting an image point charge at the kelvin point .
a natural extension is the problem of a dielectric sphere inside a different dielectric background , where a single point image charge no longer works . in 1883.
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carl neumann @xcite discovered that a point image at the kelvin point together with a line image starting from the kelvin point to infinity solves the boundary condition .
this result has been independently re - derived by several authors , up to 1990s ; see the reviews @xcite for more details .
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Suppose that you have an abstract for a scientific paper: we have used the hartree - fock random phase approximation ( hf - rpa ) to study the interacting electron gas in a quantum wire .
the spectra of intersubband spin - flip excitations reveal a considerable red shift with respect to single - particle hf energies . that signals on appearance of collective intersubband spind - density excitations due to the exchange interaction .
the long wavelength dispersions of the intrasubband collective spin - density excitations are linear , but the sound velocities are renormalised due to the exchange interaction and screening
. the in - phase intrasubband charge - density excitation has the long wavelength form @xmath0^{1/2}$ ] .
we found good qualitative agreement of our results with experimental observations .
a semiconductor quantum wire can be fabricated by applying a voltage with a microstructured gate to a 2d electron gas .
the single - particle energy ( spe ) spectrum typically consists of subbands separated by several @xmath1 . at a 1d electron density about @xmath2@xmath3
more than one subband can be occupied . in recent years progress has been made in spectroscopic study of such systems . in angular
resolved raman spectra of gaas quantum wires@xcite , collective spin - density excitations ( sde ) and charge - density excitations ( cde , or plasmons ) were observed .
the measured spectra cover from low to high frequency , and for low - frequency intrasubband excitations , the wave - vector dependence of the spin - wave energy was found to be linear .
the correct interpretation of these experiments allows us not only to understand the interesting physical processes , but also to access important physical parameters .
the exchange interaction is crucial to the collective intrasubband and intersubband sde .
similar to the direct long range coulomb interaction which leads to the depolarisation shift of single - particle excitations and to the appearance of collective plasma modes , exchange interaction gives rise to the red - shift of....
And you have already written the first three sentences of the full article: .
Please generate the next two sentences of the article
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Suppose that you have an abstract for a scientific paper: we perform a first- principles derivation of the general master equation to study the non - markovian dynamics of a two - level atom ( 2la ) interacting with an electromagnetic field ( emf ) .
we use the influence functional method which can incorporate the full backreaction of the field on the atom , while adopting grassmannian variables for the 2la and the coherent state representation for the emf .
we find exact master equations for the cases of a free quantum field and a cavity field in the vacuum . in response to the search for mechanisms to preserve maximal coherence in quantum computations in ion trap prototypes , we apply these equations to analyse the decoherence of a 2la in an emf , and fine that decoherence time is close to relaxation time .
this is at variance to the claims by authors who studied the same system but used a different coupling model .
we explain the source of difference and argue that , contrary to common belief , the emf when resonantly coupled to an atom does not decohere it as efficiently as a bath does on a quantum brownian particle . the master - equations for non - markovian dynamics derived here
is expected to be useful for exploring new regimes of 2la - emf interaction , which is becoming physically important experimentally .
c i u plus 1000pt minus 1000pt # 1 # 1= to # 1= to # 1nucl .
phys .
# 1 # 1phys .
lett .
# 1 # 1phys .
rev .
lett .
# 1 # 1phys . rev . *
d * # 1 # 1phys . rev . * a * # 1 # 1prog .
theor .
phys .
# 1 #1astron . and astrophys .
# 1 # 1@xmath0 # 1 # 1)([#1 ] ) # 1(#1 ) = 8.5 in = 6.5 in = -.5 in = 0.in = 0.in addtoresetequationsection .
And you have already written the first three sentences of the full article: a two - level system ( 2ls ) interacting with a quantum field electromagnetic field ( emf ) in particular has proven to be a very useful model for a wide range of problems from atomic - optical @xcite and condensed matter @xcite processes to quantum computation @xcite . for the latter application stringent limits in maintaining the coherence of the the 2ls ( called qubits )
are required .
this prompted us to revisit the theoretical structure of the 2ls model , paying special attention to its coherence properties ..
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treatment of spontaneous emission and relaxation are standard textbook topics , whereas decoherence and dissipation , especially in the context of quantum computation , are the focus of more recent investigations @xcite .
because of the familiarity of the model ( see ii.a ) and its theoretical and practical values , we do not need to emphasize the general motivation , but can go right to the point about the aim and results of this paper .
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Suppose that you have an abstract for a scientific paper: we propose a novel measure of degree heterogeneity , for unweighted and undirected complex networks , which requires only the degree distribution of the network for its computation .
we show that the proposed measure can be applied to all types of network topology with ease and increases with the diversity of node degrees in the network .
the measure is applied to compute the heterogeneity of synthetic ( both random and scale free ) and real world networks with its value normalized in the interval @xmath0 $ ] . to define the measure ,
we introduce a limiting network whose heterogeneity can be expressed analytically with the value tending to 1 as the size of the network @xmath1 tends to infinity .
we numerically study the variation of heterogeneity for random graphs ( as a function of @xmath2 and @xmath1 ) and for scale free networks with @xmath3 and @xmath1 as variables . finally , as a specific application
, we show that the proposed measure can be used to compare the heterogeneity of recurrence networks constructed from the time series of several low dimensional chaotic attractors , thereby providing a single index to compare the structural complexity of chaotic attractors . * keywords : complex networks , heterogeneity measure , recurrence network analysis * .
And you have already written the first three sentences of the full article: a network is an abstract entity consisting of a certain number of nodes connected by links or edges .
the number of nodes that can be reached from a reference node @xmath4 in one step is called its degree denoted by @xmath5 . if equal number of nodes can be reached in one step from all the nodes , the network is said to be regular or homogeneous .
a regular lattice where nodes are associated with fixed locations in space and each node connected to equal number of nearest neighbours , is an example of a regular network ..
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however , in the general context of complex networks , it is defined in an abstract space with a set of nodes @xmath6 and a set of links denoted by @xmath7 . as the spectrum of @xmath8 values of the nodes increases ,
the network becomes more and more irregular and complex . over the last two decades
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Suppose that you have an abstract for a scientific paper: when studying the thermodynamic properties of mesoscopic systems the most appropriate microcanonical entropy is the volume entropy , i.e. the logarithm of the volume of phase space enclosed by the hypersurface of constant energy . for systems with broken ergodicity ,
the volume entropy has discontinuous jumps at values of energy that correspond to separatrix trajectories .
simultaneously there is a convex intruder in the entropy function and a region of negative specific heat below such critical energies .
we illustrate this with a simple model composed of a chain of 3 particles which interact via a lennard - jones potential . .
And you have already written the first three sentences of the full article: the work of d.h.e .
gross @xcite has recently pointed out the attention on the fact that a microcanonical description of systems which may display phase transitions is in general more adequate than the traditional canonical one .
this is because the canonical description may `` smear out '' important information contained in the microcanonical description which is richer @xcite ..
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for example negative specific heats , which have recently been observed experimentally in mesoscopic systems @xcite , can be accounted for in the microcanonical ensemble but not in the canonical one @xcite .
indeed it is well known that canonical ensemble and microcanonical ensemble are not in general equivalent , even when the thermodynamic limit is considered @xcite .
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Suppose that you have an abstract for a scientific paper: high - energy collisions at the lhc are now starting .
the new physics agenda of the lhc is reviewed , with emphasis on the hunt for the higgs boson ( or whatever replaces it ) and supersymmetry .
in particular , the prospects for discovering new physics in the 2010 - 2011 run are discussed .
cern - ph - th/2010 - 074 .
And you have already written the first three sentences of the full article: back in the dawn of prehistory , when i was a student , murray gell - mann was an inspiration to me . his work dominated the particle physics landscape that i entered then : strangeness , @xmath0 theory , the eightfold way , quarks , current algebra , the renormalization group , and so much more , and laid the basis for the developments that have occurred since .
these fundamental contributions are now so embedded in the fabric of particle physics that perhaps we sometimes forget to remember them and celebrate their originator with all the respect he deserves .
it is therefore a pleasure for me to participate in this meeting honouring murray and his achievements , and a privilege to be given the opportunity to speak here about the next chapter in particle physics that is now unfolding ..
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there is a standard list of open questions beyond the standard model of particle physics .
what is the origin of particle masses , and are they due to a single elementary higgs boson , or to something else ?
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Suppose that you have an abstract for a scientific paper: the fusion hindrance in heavy ion collisions is studied in the framework of the two - center liquid drop model .
it appears that the neck and the radial degrees of freedom might both be hampered by an inner potential barrier on their path between the contact configuration to the compound nucleus .
heavy ion reactions with and without the two kinds of fusion hindrance are classified through systematic calculations .
it is found that the number of reactions without radial fusion hindrance is much smaller than that without neck fusion hindrance , and for both kinds of fusion hindrance the number of reactions without fusion hindrance at small mass - asymmetry parameter @xmath0 is smaller than that at large @xmath0 . in the formation of a given compound nucleus ,
if a reaction with @xmath1 is not hindered , then other reactions with @xmath2 are also not hindered as it is well known experimentally . .
And you have already written the first three sentences of the full article: the fusion hindrance that appears in heavy ion reactions has been known for many years . now
the mechanism of fusion hindrance is gradually understood as to be due to an extra internal barrier between the touching configuration and the compound shape after overcoming the coulomb barrier @xcite .
however what causes the internal barrier is a difficult problem ..
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one of the hypotheses is that the internal barrier could be thought as the conditional saddle point in the liquid - drop potential as well as could be attributed to an effective barrier due to the dissipation of the incident kinetic energy @xcite .
since there are two barriers for the fusion , its theoretical description is divided into two consecutive steps : one is from infinity to the contact configuration passing over the coulomb barrier , and another one is from the contact point to the compound state overcoming the internal barrier .
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Suppose that you have an abstract for a scientific paper: we report the detection of a 3.6@xmath0 350@xmath1m - selected source in the botes deep field .
the source , the first short - wavelength submillimeter - selected galaxy ( ssg 1 ) , was discovered as part of a blank field extragalactic survey using the 350@xmath1m - optimised submillimeter high angular resolution camera ( sharc ii ) at the caltech submillimeter observatory . with multiwavelength photometry from noao - ndwfs ( r and i band ) , flamex ( j and k@xmath2 ) , _ spitzer _ ( irac and mips ) and the westerbork 1.4ghz deep survey ( radio upper limit ) , we are able to constrain the photometric redshift using different methods , all of which suggest a redshift @xmath31 . in the absence of long - wavelength submillimeter data we use sed templates to infer that this source is an ultraluminous infrared galaxy ( ulirg ) with a dust temperature of 30@xmath45k , occupying a region of luminosity - temperature space shared by modarate redshift _ iso_-selected ulirgs ( rather than high redshift scuba - selected smgs ) .
sharc ii can thus select smgs with moderately `` warm '' dust that might be missed in submillimeter surveys at longer wavelengths . .
And you have already written the first three sentences of the full article: submillimeter - selected galaxies ( smgs ) generally refer to the population detected in the pioneering lensed and blank deep field surveys using the submillimeter common user bolometer array ( scuba ; holland et al .
1999 ) instrument on the james clerk maxwell telescope ( jcmt ) ( e.g. , smail , ivison & blain 1997 ; hughes et al .
1998 ; barger et al . 1998 ; eales et al . 1999 ) ..
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they are regarded as the high redshift ( z@xmath323 ; chapman et al .
2005 ; chapman et al .
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Suppose that you have an abstract for a scientific paper: recent numerical analysis of keplerian disk formation in turbulent , magnetized cloud cores by @xcite demonstrated that reconnection diffusion is an efficient process to remove the magnetic flux excess during the build up of a rotationally supported disk .
this process is induced by fast reconnection of the magnetic fields in a turbulent flow . in a similar numerical study
, @xcite concluded that reconnection diffusion or any other non - ideal mhd effects would not be necessary and turbulence shear alone would provide a natural way to build up a rotating disk without requiring magnetic flux loss .
their conclusion was based on the fact that the mean mass - to - flux ratio ( @xmath0 ) evaluated over a spherical region with a radius much larger than the disk is nearly constant in their models . in this letter
we compare the two sets of simulations and show that this averaging over large scales can mask significant real increases of @xmath0 in the inner regions where the disk is built up .
we demonstrate that turbulence - induced reconnection diffusion of the magnetic field happens in the initial stages of the disk formation in the turbulent envelope material that is accreting .
our analysis is suggestive that reconnection diffusion is present in both sets of simulations and provides a simple solution for the `` magnetic braking catastrophe '' which is discussed in the literature in relation to the formation of protostellar accretion disks .
[ firstpage ] diffusion ism : magnetic fields mhd turbulence star formation accretion disks .
And you have already written the first three sentences of the full article: star formation theory for decades developed under the assumption that magnetic flux is frozen in highly conducting interstellar gas , unless a process of ambipolar diffusion carries neutrals across the magnetic field lines @xcite .
the flux freezing is , however , violated in turbulent fluids due to fast reconnection @xcite ( henceforth lv99 ) .
this prediction is now not only supported by successful numerical tests @xcite and observations @xcite , but also by formal mathematical derivations based on modern understanding of the lagrangian properties of mhd turbulence ( @xcite ) ..
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the diffusion of magnetic fields mediated by reconnection in turbulent fluids was predicted to be important for star formation by lazarian ( 2005 ) .
the process should be widely spread as turbulence is ubiquitous in the interstellar media ( armstrong et al .
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Suppose that you have an abstract for a scientific paper: we analyze neutral higgs boson decays into squark pairs in the minimal supersymmetric extension of the standard model and improve previous analyses .
in particular the treatment of potentially large higher - order corrections originating from the soft susy breaking parameters @xmath0 , the trilinear higgs coupling to sbottoms , and @xmath1 , the higgsino mass parameter , is investigated .
the remaining theoretical uncertainties including the susy - qcd corrections are analyzed quantitatively .
-1.0 cm psi
pr1101 neutral higgs boson decays to squark pairs reanalyzed e. accomando@xmath2 , g. chachamis@xmath3 , f. fugel@xmath3 , m. spira@xmath3 and m. walser@xmath4 _ @xmath2 university of southampton , theory group , southampton so17 1bj , united kingdom + @xmath3 paul scherrer institut , ch-5232 villigen psi , switzerland + @xmath5 institute for theoretical physics , eth zrich , ch8093 zrich , switzerland _ .
And you have already written the first three sentences of the full article: the search for higgs bosons plays one of the most important roles at high - energy collider experiments at the tevatron and the lhc .
the higgs boson is the remnant of electroweak symmetry breaking in the scalar higgs sector of the standard model ( sm ) and its supersymmetric extensions .
the minimal supersymmetric extension of the sm ( mssm ) requires the introduction of two higgs doublets in order to preserve supersymmetry @xcite ..
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this leads to the existence of five elementary higgs particles , two cp - even ( @xmath6 ) , one cp - odd ( @xmath7 ) and two charged ( @xmath8 ) states . at lowest order ( lo ) all couplings and masses of the mssm higgs sector
are described by two independent input parameters , which are usually chosen as @xmath9 , the ratio of the two vacuum expectation values @xmath10 , and the pseudoscalar higgs - boson mass @xmath11 . at lo ,
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Suppose that you have an abstract for a scientific paper: since 2007 , the telescope array ( ta ) experiment , based in utah , usa , has been observing ultra high energy cosmic rays to understand their origins .
the experiment involves a surface detector ( sd ) array and three fluorescence detector ( fd ) stations .
fd stations , installed surrounding the sd array , measure the air fluorescence light emitted from extensive air showers ( eass ) for precise determination of their energies and species .
the detectors employed at one of the three fd stations were relocated from the high resolution fly s eye experiment . at the other two stations ,
newly designed detectors were constructed for the ta experiment .
an fd consists of a primary mirror and a camera equipped with photomultiplier tubes . to obtain the eas parameters with high accuracies , understanding the fd optical characteristics
is important . in this paper , we report the characteristics and installation of new fds and the performances of the fd components .
the results of the monitored mirror reflectance during the observation time are also described in this report .
ultra high energy cosmic rays , extensive air showers , air fluorescence light detectors .
And you have already written the first three sentences of the full article: the telescope array project is a collaboration with 120 scientists from four nations ( japan , usa , korea , and russia ) , with the observatory located in utah , usa @xcite .
the detectors involved in the telescope array experiment consist of surface detectors ( sds ) arranged in an array and fluorescence detector ( fd ) telescopes . fig .
[ ta_map ] shows the detector map ( squares : sd positions , triangles : fd station positions ) ..
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the sd array consists of 507 sds , arranged over an area of approximately 700 km@xmath0 with 1.2 km spacing between the sds @xcite .
the sds measure the arrival timing and particle densities of extensive air showers ( eass ) using two - layered plastic scintillators of 3 m@xmath1 .
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Suppose that you have an abstract for a scientific paper: we study the stability of a bose - einstein condensate of harmonically trapped atoms with negative scattering length , specifically @xmath0li .
our method is to solve the time - dependent nonlinear schrdinger equation numerically . for an isolated condensate , with no gain or loss , we find that the system is stable ( apart from quantum tunneling ) if the particle number @xmath1 is less than a critical number @xmath2 for @xmath3 , the system collapses to high - density clumps in a region near the center of the trap .
the time for the onset of collapse is on the order of 1 trap period . within numerical uncertainty ,
the results are consistent with the formation of a `` black hole '' of infinite density fluctuations , as predicted by ueda and huang @xcite .
we obtain numerically @xmath4 .
we then include gain - loss mechanisms , i.e. , the gain of atoms from a surrounding `` thermal cloud '' , and the loss due to two- and three - body collisions .
the number @xmath1 now oscillates in a steady state , with a period of about 145 trap periods .
we obtain @xmath5 as the maximum value in the oscillations
. boxedeps [ theorem]acknowledgement [ theorem]algorithm [ theorem]axiom [ theorem]claim [ theorem]conclusion [ theorem]condition [ theorem]conjecture [ theorem]corollary [ theorem]criterion [ theorem]definition [ theorem]example [ theorem]exercise [ theorem]lemma [ theorem]notation [ theorem]problem [ theorem]proposition [ theorem]remark [ theorem]solution [ theorem]summary .
And you have already written the first three sentences of the full article: bose - einstein condensation has been observed in magnetically trapped dilute vapors of@xmath6 the alkali elements @xmath7rb @xcite , @xmath8na @xcite , @xmath0li @xcite , and @xmath9h @xcite . at the nanodegree temperatures of these experiments ,
the systems would have frozen solid long ago were they in free space . in the confining trap , however , zero - point motion keeps the atoms apart , and the systems remain gaseous .
the case of @xmath0li is special , however , in that the interatomic interaction is predominantly attractive , as indicated by a negative scattering length ..
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thus , the condensate in @xmath0li should be less stable than the other cases .
the purpose of this paper is to study the nature of the instability , its onset , and manifestations .
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Suppose that you have an abstract for a scientific paper: a generalized probe sequence typical of trapped ion experiments using shelving is studied .
detection efficiency is analyzed for finite shelved state lifetimes and using multi - modal count distributions .
multi - modal distributions are more appropriate for measurements that use a small number of ions than the simple poisson counting statistics usually considered and have a larger variance that may be significant in determining uncertainties and in making weighted fits .
optimal probe times and the resulting state detection efficiency and sensitivity are determined for arbitrary cooling rates , initial states and shelved state lifetimes , in terms of a probe coherance time @xmath0 . a universal optimal probe time of @xmath1 is shown to give an almost optimal probe sensitivity for most systems . .
And you have already written the first three sentences of the full article: experiments using trapped ions often provide a superior system for making precision measurements in applications such as determining atomic structure parameters[[sherman ] ] , microwave or optimal atomic clocks[[warrington],[itano ] ] , searches for time variations of fundamental constants[[itano],[peik ] ] , or making precision measurements of atomic parity violation[[fortson - ionpnc],[schacht],[koerber ] ] .
the precision possible in such experiments is fundamentally due to the intrinsic properties of a trapped ion system through its relatively clean and isolated environment , but is finally determined as it is for all experiments by systematics and sensitivity .
systematic issues are commonly analyzed extensively , but sensitivity has not yet been considered in the detail common to many more traditional precision atomic measurements such as atomic parity violation[[vetter],[wood ] ] . a careful consideration of the choice of certain experimental parameters can yield important improvements in sensitivity for many kinds of experiments and a corresponding improvement in the precision possible ..
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trapped ion experiments typically consist of many trials of some pump , interaction , probe sequence .
the pump stage prepares the ion in a particular state . during the interaction stage
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Suppose that you have an abstract for a scientific paper: during flares and coronal mass ejections , energetic electrons from coronal sources typically have very long lifetimes compared to the transit times across the systems , suggesting confinement in the source region .
particle - in - cell simulations are carried out to explore the mechanisms of energetic electron transport from the corona to the chromosphere and possible confinement .
we set up an initial system of pre - accelerated hot electrons in contact with ambient cold electrons along the local magnetic field , and let it evolve over time .
suppression of transport by a nonlinear , highly localized electrostatic electric field ( in the form of a double layer ) is observed after a short phase of free - streaming by hot electrons . the double layer ( dl )
emerges at the contact of the two electron populations .
it is driven by an ion - electron streaming instability due to the drift of the back - streaming return current electrons interacting with the ions .
the dl grows over time and supports a significant drop in temperature and hence reduces heat flux between the two regions that is sustained for the duration of the simulation .
this study shows transport suppression begins when the energetic electrons start to propagate away from a coronal acceleration site .
it also implies confinement of energetic electrons with kinetic energies less than the electrostatic energy of the dl for the dl lifetime , which is much longer than the electron transit time through the source region . .
And you have already written the first three sentences of the full article: in flares and coronal mass ejections , coronal electrons can be accelerated above 100 kev @xcite , i.e. , more than three orders of magnitudes higher than the ambient coronal temperature of 100 ev .
the energy is ultimately believed to come from magnetic fields through magnetic reconnection , which occurs throughout the corona .
x - rays and microwaves produced by these energetic electrons are observed in both the chromosphere and the corona ..
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how energetic electrons are transported from a coronal acceleration site to the chromosphere is a key issue in understanding the dynamics of flares .
recent time - of - flight measurements of hard x - ray emission during solar flares @xcite report relative time delays of arrival at the chromosphere by electrons of different energies propagating from the coronal acceleration site .
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Suppose that you have an abstract for a scientific paper: physicists believe , with some justification , that there should be a correspondence between familiar properties of newtonian gravity and properties of solutions of the einstein equations . the positive mass theorem ( pmt ) , first proved over twenty years ago @xcite , is a remarkable testament to this faith . however , fundamental mathematical questions concerning mass in general relativity remain , associated with the definition and properties of quasi - local mass .
central themes are the structure of metrics with non - negative scalar curvature , and the role played by minimal area 2-spheres ( black holes ) .
4.5 mm * 2000 mathematics subject classification : * 53c99 , 83c57 . * keywords and phrases : * quasi - local mass , einstein equations , scalar curvature . .
And you have already written the first three sentences of the full article: -5 mm the positive mass theorem provides a good example of _ `` the unreasonable effectiveness of physics in mathematics''_. the need to define mass in general relativity is motivated directly by the physics imperative to establish a correspondence between general relativity and classical newtonian gravity .
already difficulties arise : although the vacuum einstein equations @xmath0 for the lorentz metric @xmath1 suggest ( by analogy with the wave equation , for example ) that a mass ( energy ) which includes contributions from the gravitational field , should be built from the first derivatives of the field @xmath1 , it is clear that this is incompatible with coordinate invariance . the schwarzschild vacuum spacetime metric , for @xmath2
, @xmath3 provides an important clue , since the parameter @xmath4 governs the behaviour of timelike geodesics and may be regarded as the total mass . note that @xmath5 ensures the boundary @xmath6 is smooth and totally geodesic in the hypersurfaces @xmath7 ..
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a riemannian 3-manifold @xmath8 is said to be _ asymptotically flat _
if @xmath9 for some compact @xmath10 , and @xmath11 admits a metric @xmath12 which is flat outside @xmath10 , and the metric components @xmath13 in the induced rectangular coordinates satisfy @xmath14 the total mass of @xmath8 is defined informally by @xcite @xmath15 if the scalar curvature @xmath16 then @xmath17 is well - defined , independent of the choices of rectangular coordinates and of exhaustion of @xmath11 used to define @xmath18 see @xcite for weaker decay and smoothness assumptions . for simplicity ,
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Suppose that you have an abstract for a scientific paper: we report on the x - ray spectral properties of 10 short bursts from sgr 1900 + 14 observed with the narrow field instruments onboard _
bepposax _ in the hours following the intermediate flare of 2001 april 18 .
burst durations are typically shorter than 1 s , and often show significant temporal structure on time scales as short as @xmath010 ms .
burst spectra from the mecs and pds instruments were fit across an energy range from 1.5 to above 100 kev .
we fit several spectral models and assumed @xmath1 values smaller than 5@xmath2 @xmath3 , as derived from observations in the persistent emission .
our results show that the widely used _ optically thin thermal bremsstrahlung _ law provides acceptable spectral fits for energies higher than 15 kev , but severely overestimated the flux at lower energies .
similar behavior had been observed several years ago in short bursts from sgr 1806 - 20 , suggesting that the rollover of the spectrum at low energies is a universal property of this class of sources .
alternative spectral models - such as two blackbodies or a cut - off power law - provide significantly better fits to the broad band spectral data , and show that all the ten bursts have spectra consistent with the same spectral shape . .
And you have already written the first three sentences of the full article: the bursting activity from sgr 1900 + 14 is quite diverse .
the most common bursts observed are the recurrent , short bursts ( e.g. , aptekar et al .
they usually have durations of a few hundreds of ms and peak luminosities reaching @xmath010@xmath4 erg s@xmath5 ( for an assumed distance of 10 kpc ) ..
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the most rare but very luminous events are the so called ` giant ' flares : to now only one has been observed from sgr 1900 + 14 on 1998 august 27 ( feroci et al . 1999 , hurley et al .
1999b ) . the burst had a duration of about 300 s and its time evolution was characterized by a very intense , short and hard peak followed by a decaying tail that showed coherent pulsations at the frequency of the persistent pulsed emission .
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Suppose that you have an abstract for a scientific paper: fluctuation relations ( frs ) are among the few existing general results in non - equilibrium systems .
their verification requires the measurement of the total work ( or entropy production ) performed on a system .
nevertheless in many cases only a partial measurement of the work is possible .
here we consider frs in dual - trap optical tweezers where two different forces ( one per trap ) are measured . with this setup
we perform pulling experiments on single molecules by moving one trap relative to the other .
we demonstrate that work should be measured using the force exerted by the trap that is moved .
the force that is measured in the trap at rest fails to provide the full dissipation in the system leading to a ( incorrect ) work definition that does not satisfy the fr .
the implications to single - molecule experiments and free energy measurements are discussed . in the case of symmetric setups a new work definition , based on differential force measurements ,
is introduced .
this definition is best suited to measure free energies as it shows faster convergence of estimators .
we discuss measurements using the ( incorrect ) work definition as an example of partial work measurement .
we show how to infer the full work distribution from the partial one via the fr .
the inference process does also yield quantitative information , e.g. the hydrodynamic drag on the dumbbell .
results are also obtained for asymmetric dual - trap setups .
we suggest that this kind of inference could represent a new and general application of frs to extract information about irreversible processes in small systems . .
And you have already written the first three sentences of the full article: fluctuation relations ( frs ) provide general results about the full work ( or entropy production ) distributions in non - equilibrium systems . however , in many cases the full work is not measurable and only partial work measurements are possible .
the latter do not fulfill a fr and can not be used to extract free energy differences from irreversible work measurements .
we propose a new application of frs to infer the full work distribution from partial work measurements ..
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we prove this new type of inference using dual - trap optical tweezers where two forces ( one per trap ) are measured , allowing us to derive full and partial work distributions .
we derive a set of results of direct interest to single molecule scientists and , more in general , to physicists and biophysicists .
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Suppose that you have an abstract for a scientific paper: observations of the high redshift universe , interpreted in the context of a new generation of computer simulated model universes , are providing new insights into the processes by which galaxies and quasars form and evolve , as well as the relationship between the formation of virialized , star - forming systems and the evolution of the intergalactic medium .
we describe our recent measurements of the star - formation rates , stellar populations , and structure of galaxies and protogalactic fragments at @xmath02.5 , including narrow - band imaging in the near - ir , ir spectroscopy , and deep imaging from the ground and from space , using @xmath1 and @xmath2 . .
And you have already written the first three sentences of the full article: observations of the hubble deep field , and other surveys of high redshift galaxies described in these proceedings , are contributing to a new picture of how large galaxies such as the milky way were assembled .
one interpretation of the data so far is that large galaxies collapse out of what appears as several star - forming proto - galactic fragments at @xmath3 ( pascarelle et al .
1996 ; haehnelt , steinmetz @xmath4 rauch 1998 ) . here.
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we describe our search for h@xmath5 emission from the star - forming regions in high redshift galaxies , which is redshifted into the near - infrared .
we focus on one of the outstanding questions about these objects : is the burst of star - formation seen in the uv continuum producing the dominant stellar population ( by mass ) ?
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10,379 |
Suppose that you have an abstract for a scientific paper: in dense clusters a bewildering variety of interactions between stars can be observed , ranging from simple encounters to collisions and other mass - transfer encounters . with faster and special - purpose computers like grape
, the amount of data per simulation is now exceeding 1 tb . visualization of such data has now become a complex 4d data - mining problem , combining space and time , and finding interesting events in these large datasets .
we have recently starting using the virtual reality simulator , installed in the hayden planetarium in the american museum for natural history , to tackle some of these problem .
reports on our first `` observations '' , modifications needed for our specific experiments , and perhaps field ideas for other fields in science which can benefit from such immersion .
we also discuss how our normal analysis programs can be interfaced with this kind of visualization . .
And you have already written the first three sentences of the full article: ( teuben 1994 ) and are traditional programming environments with which n - body simulations can be setup , run and analyzed .
nemo also has a number of tools to import and export data in tables , ccd type images , fits files and a large number of other n - body formats .
nemo is more geared towards collisionless stellar dynamics , while starlab has more sophisticated programs to deal with close encounters , and can now also incorporate stellar evolution through the seba package ( portegies zwart et al . 2001 ) ..
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nemo and starlab present themselves to a user as a large set of programs , often glued together using pipes in shell scripts to set up and run complex simulations . for the programmer ,
a large set of classes and functions are available to construct new integrators and analysis programs .
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10,380 |
Suppose that you have an abstract for a scientific paper: brane - world models offer the possibility of explaining the late acceleration of the universe via infra - red modifications to general relativity , rather than a dark energy field .
however , one also expects ultra - violet modifications to general relativity , when high - energy stringy effects in the early universe begin to grow .
we generalize the dgp brane - world model via an ultra - violet modification , in the form of a gauss - bonnet term in the bulk action .
the combination of infra - red and ultra - violet modifications produces an intriguing cosmology .
the dgp feature of late - time acceleration without dark energy is preserved , but there is an entirely new feature there is no infinite - temperature big bang in the early universe .
the universe starts with finite density and pressure , from a sudden " curvature singularity . .
And you have already written the first three sentences of the full article: the standard cosmology based on general relativity and inflation has been remarkably successful .
but there remain deep puzzles left for theorists to resolve what is the cause of the late - time acceleration of the universe ( the dark energy " problem ) ?
how is the classical big bang singularity removed by quantum gravity effects ?.
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one approach to start tackling these problems is via the brane - world scenario , which is motivated by string theory .
most brane - world models , including those of randall - sundrum type @xcite , produce ultra - violet modifications to general relativity , with extra - dimensional gravity dominating at high energies .
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10,381 |
Suppose that you have an abstract for a scientific paper: the effect of the residual interaction between the nucleons ( quasiparticles ) on the thermodynamic behavior of spherical nuclei is considered .
thermodynamic relations are derived for the simplest model of the residual interaction that has the necessary macroscopic structure previously established .
the range of applicability of the theory is discussed . .
And you have already written the first three sentences of the full article: the nuclear physics data accumulated up to now indicate that there is an essential difference between spherical and nonspherical nuclei .
this difference does not reduce merely to nuclear shape effects " as such , but intimately involves the internal structure of the nucleus .
the shell oscillations of nuclear masses [ 1 ] can serve as an example of the phenomena associated with the difference between the structures of spherical and nonspherical nuclei ..
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the shell oscillations are due to the ordered grouping of one - quasiparticle levels in spherical nuclei that arises because of the existence of the orbital angular momentum quantum number @xmath0 of the quasiparticle [ 1,2 ] .
there is no such ordered grouping in nonspherical nuclei , and the trend of the mass of such nuclei as a function of the number of nucleons is entirely different .
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10,382 |
Suppose that you have an abstract for a scientific paper: in this spectroscopic study of infant massive star clusters , we find that continuum emission from ionized gas rivals the stellar luminosity at optical wavelengths .
in addition , we find that nebular line emission is significant in many commonly used broad - band _ hubble space telescope ( hst ) _ filters including the f814w @xmath0-band , the f555w @xmath1-band and the f435w @xmath2-band . two young massive clusters ( ymcs ) in the nearby starburst galaxy ngc 4449 were targeted for follow - up spectroscopic observations after @xcite discovered an f814w @xmath0-band excess in their photometric study of radio - detected clusters in the galaxy . the spectra were obtained with the dual imaging spectrograph ( dis ) on the 3.5 m apache point observatory ( apo ) telescope and have a spectral range of @xmath33800 - 9800 .
we supplement these data with _ hst _ and sloan digital sky survey ( sdss ) photometry of the clusters . by comparing our data to the starburst99 and galev evolutionary synthesis models , we find that nebular continuum emission competes with the stellar light in our observations and that the relative contribution from the nebular continuum is largest in the @xmath4- and @xmath0-bands , where the balmer ( 3646 ) and paschen jumps ( 8207 ) are located .
the spectra also exhibit strong line emission including the [ s iii ] @xmath5 lines in the _ hst _
f814w @xmath0-band .
we find that the _ combination _ of nebular continuum and line emission can account for the f814w @xmath0-band excess previously found by @xcite . in an effort to provide a benchmark for estimating the impact of ionized gas emission on photometric observations of young massive stellar populations , we compute the relative contributions of the stellar continuum , nebular continuum , and emission lines to the total observed flux of a 3 myr - old cluster through various _ hst _ filter / instrument combinations , including filters in the wide field camera 3 ( wfc3 ) .
we urge caution when comparing observations of....
And you have already written the first three sentences of the full article: massive star clusters are an important mode of star formation , having an impact on a wide range of galaxy properties .
however , the earliest stages of these clusters are notoriously challenging to study since the youngest clusters are still enshrouded in remnants of their gaseous and dusty birth cocoons . properly accounting for the effects of gas and dust on observations of young massive clusters ( ymcs )
is nontrivial , rendering it difficult to understand their formation and earliest phases of evolution ..
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some of these difficulties , such as interstellar extinction , are commonly dealt with in studies of young star clusters . while it is often not possible to completely disentangle the effects of extinction , the general effects are well - known and accounted for ( e.g. * ? ? ?
* ; * ? ? ?
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10,383 |
Suppose that you have an abstract for a scientific paper: any singular deviation from landau fermi - liquid theory appears to lead , for arbitrarily small concentration of impurities coupling to a non - conserved quantity , to a vanishing density of states at the chemical potential and infinite resistivity as temperature approaches zero .
applications to copper - oxide metals including the temperature dependence of the anisotropy in resistivity , and to other cases of non fermi - liquids are discussed .
the resistivity in the c - direction , @xmath0 , in the normal phase of most copper - oxide ( cuo ) compounds increases with decreasing temperature while the inplane resistivity @xmath1 has the opposite behavior , which for compositions near those for the highest @xmath2 is proportional to @xmath3 down to @xmath4.@xmath5 one may be led to suppose that , if superconductivity were not to intervene , @xmath6 while @xmath7 finite value as @xmath8 . for any finite quantum - mechanical transfer matrix element @xmath9 between adjacent planes ,
the asymptotic low temperature dependence in different directions must be identical for @xmath10 , where @xmath11 here @xmath12 is the inelastic scattering rate .
anderson and zhou@xmath13 conjectured that the renormalized matrix elements @xmath14 in cuo compounds at low temperatures due to orthogonality effects .
an alternative conjecture@xmath15 put forward to resolve the issue is that @xmath16 also @xmath17 as @xmath8 due to impurity scattering in a non fermi - liquid .
recent experiments@xmath18 measuring the resistivity at low temperatures by suppressing @xmath2 in a large magnetic field support this conjecture and find @xmath19 at low temperature .
similar behavior is also found ( without applying a magnetic field ) in samples of the single layer bi compound.@xmath20 here theoretical support for the conjecture that the resistivity of a non - fermi - liquid is infinity for @xmath8 for any finite concentration of impurities as well as the logarithm temperature dependence are obtained . a landau fermi - liquid....
And you have already written the first three sentences of the full article: 1 . see for example b. batlogg in _ high temperature superconductivity_.
the los alamos symposium - 1989 , edited by k. s. bedell et al .
( addison wesley , reading , ma ; 1989 ) ..
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2 . p. w. anderson and z. zhou , phys .
rev . lett . * 60 * , 2557 ( 1988 ) .
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10,384 |
Suppose that you have an abstract for a scientific paper: we find that the total spectrum of electron states in a bounded 2d electron gas with spin - orbit interaction contains two types of evanescent states lying in different energy ranges .
the first - type states fill in a gap , which opens in the band of propagating spin - splitted states if tangential momentum is nonzero .
they are described by a pure imaginary wavevector .
the states of second type lie in the forbidden band .
they are described by a complex wavevector .
these states give rise to unusual features of the electron transmission through a lateral potential barrier with spin - orbit interaction , such as an oscillatory dependence of the tunneling coefficient on the barrier width and electron energy .
but of most interest is the spin polarization of an unpolarized incident electron flow .
particularly , the transmitted electron current acquires spin polarization even if the distribution function of incident electrons is symmetric with respect to the transverse momentum .
the polarization efficiency is an oscillatory function of the barrier width .
spin filtering is most effective , if the fermi energy is close to the barrier height . .
And you have already written the first three sentences of the full article: the spin - orbit interaction ( soi ) in low - dimensional structures attracts a great deal of interest since it opens up the possibility to manipulate the electron spin in nonmagnetic structures using electrical means .
@xcite in this view , semiconductor heterostructures with 2d electrons are very promising since the rashba soi is effectively controlled @xcite by varying applied bias or gate voltages .
in recent years , predominant interest was paid to effects appearing when the soi modifies propagating electron modes with energy above the conduction band bottom ..
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suffice it to mention the spin - hall effect , @xcite or spin manipulation in strained semiconductors @xcite . in this paper
we show that interesting effects of the soi arise also when the electron energy is lower than or near to the conduction band bottom and evanescent states are involved .
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10,385 |
Suppose that you have an abstract for a scientific paper: we have carried out detailed experimental studies of the exchange bias effect of a series of coo / co(111 ) textured bilayers with different co layer thickness , using the magneto - optical kerr effect , squid magnetometry , polarized neutron reflectivity , x - ray diffraction , and atomic force microscopy .
all samples exhibit a pronounced asymmetry of the magnetic hysteresis at the first magnetization reversal as compared to the second reversal .
polarized neutron reflectivity measurements show that the first reversal occurs via nucleation and domain wall motion , while the second reversal is characterized by magnetization rotation .
off - specular diffuse spin - flip scattering indicates the existence of interfacial magnetic domains .
all samples feature a small positive exchange bias just below the blocking temperature , followed by a dominating negative exchange bias field with decreasing temperature . .
And you have already written the first three sentences of the full article: the exchange bias phenomenon is associated with the interfacial exchange coupling between ferromagnetic and antiferromagnetic spin structures , resulting in an unidirectional magnetic anisotropy that causes a shift of the hysteresis loop to negative field values as one cools the system through the nel temperature of the antiferromagnet(af ) in a positive magnetic field @xcite .
the exchange bias effect is essential for the development of magneto - electronic switching devices ( spin - valves ) and for random access magnetic storage units . for these applications a predictable , robust , and tunable exchange bias effect
is required ..
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extensive data have been collected on the exchange bias field @xmath0 , and the coercivity field @xmath1 , for a large number of bilayer systems , which are reviewed in ref .
the details of the eb effect depend crucially on the af / f combination chosen and on the structure and thickness of the films .
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10,386 |
Suppose that you have an abstract for a scientific paper: through detailed electronic structure simulations we show that the electronic orbital ordering ( between d@xmath0 and d@xmath1 bands ) takes place due to local breaking of in - plane symmetry that generates two non - equivalent @xmath2 , @xmath3 directions in 122 family of fe - based superconductors .
orbital ordering is strongly anisotropic and the temperature dependence of the corner zone orbital order maps to that of the orthorhombicity parameter .
orbital anisotropy results in two distinct spin density wave nesting wave vectors and causes inter - orbital charge and spin fluctuations .
temperature dependence of the orbital order is proportional to the nematic order and it sets in at a temperature where magnetic fluctuation starts building .
magnetic fluctuations in the orthorhombic phase is characterized through evolution of stoner factor which reproduces experimental findings very accurately .
orbital ordering becomes strongly spin dependent in presence of magnetic interaction .
occupation probabilities of all the fe - d - orbitals exhibit temperature dependence indicating their possible contribution in orbital fluctuation .
this need to be contrasted with the usual definition of nematic order parameter ( n@xmath4-n@xmath5 ) .
relationship among orbital fluctuations , magnetic fluctuations and nematicity are established .
fe - based superconductors , orbital fluctuation , nematicity , spin density wave .
And you have already written the first three sentences of the full article: the discovery of high temperature superconductivity in fe - based materials attaining t@xmath6 as large as 109k @xcite , has lead to a huge up surge of research for further discovery of such new materials @xcite .
seven years after its discovery , while a clear consensus on the mechanism of superconductivity has not yet been reached , understanding on the structural , magnetic transitions and their mutual influences on superconductivity remain central issue of frontier research @xcite .
a large number of undoped fe - based materials show spin density wave ( sdw ) magnetic state whose transition temperature coincides with that of the structural transition ( which gets separated through doping as well as pressure ) ..
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both the transitions being second order in nature , can have a conflict with landau theory of phase transition unless there would be a precursor transition at higher temperatures . according to landau theory , occurrence of two simultaneous transitions
may be purely coincidental , mutually independent , or one of the transitions be first order type or there must be a precursor to one of the transitions at a higher temperature .
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10,387 |
Suppose that you have an abstract for a scientific paper: oliinychenko , bugaev and sorin [ arxiv:1204.0103 [ hep - ph ] ] considered the role of conservation laws in discussing possible weaknesses of thermal models which are utilized in describing the hadron multiplicities measured in central nucleus - nucleus collisions . they argued to analyse the criteria for chemical freeze - out and to conclude that none of them were robust .
based on this , they suggested a new chemical freeze - out criterion .
they assigned to the entropy per hadron the _ ad hoc _ value @xmath0 and supposed to remain unchanged over the whole range of the baryo - chemical potentials . due to unawareness of recent literature
, the constant entropy per hadron has been discussed in ref .
[ fizika b18 ( 2009 ) 141 - 150 , europhys.lett .
75 ( 2006 ) 420 ] .
furthermore , it has been shown that the constant entropy per hadron is equivalent to constant entropy normalized to cubic temperature , an earlier criterion for the chemical freeze - out introduced in ref .
[ europhys.lett .
75 ( 2006 ) 420 , nucl.phys.a764 ( 2006 ) 387 - 392 ] . in this comment , we list out the ignored literature , compare between the entropy - number density ratio and two criteria of averaged energy per averaged particle number and constant entropy per cubic temperature .
all these criteria are confronted to the experimental results .
the physics of constant entropy per number density is elaborated .
it is concluded that this ratio ca nt remain constant , especially at large chemical potential related to ags and sis energies . . .
And you have already written the first three sentences of the full article: in the preprint @xcite , oliinychenko , bugaev and sorin have considered the role of conservation laws , the values of hard core radii along with the effects of the lorentz contraction of hadron eigen volumes in discussing the weaknesses of thermal models which are utilized in describing the hadron multiplicities measured in the central nucleus - nucleus collisions .
regardless the unawareness of earlier literature , the authors concluded that none of the criteria for the chemical freeze - out is robust . in doing this
, they entirely disregarded the experimental results in baryo - chemical potentials @xmath1 and their corresponding temperatures @xmath2 ..
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a systematic analysis of the four criteria describing the chemical freeze - out is introduced in @xcite .
furthermore , a comparison between these four criteria is elaborated in @xcite .
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10,388 |
Suppose that you have an abstract for a scientific paper: conformation of single polyelectrolytes in tetravalent salt solutions is investigated under the framework of a coarse - grained model , using langevin dynamics simulations .
the chain size , studied by the radius of gyration , shows three different variational behaviors with salt concentration , depending on the chain stiffness . according to the size variations , polyelectrolytes of fixed chain length
are classified into three categories : ( 1 ) flexible chain , for which the variation shows a curve similar to a tilted letter l ; ( 2 ) semiflexible chain , whose curve looks resemble of the letter u ; ( 3 ) rigid chain , for which the curve is a straight line . the worm - like chain model with persistence length predicted by the odijk - skolnick - fixman theory
is found to be able to qualitatively describe the end - to - end distance at low salt concentration , not only for semiflexible and rigid chains but also for flexible chain . in a low - salt region
, a flexible polyelectrolyte extends more significantly than a semiflexible chain , in reference of the size of their uncharged counterparts , and in a high - salt region , regardless of chain stiffness , a chain attains a dimension comparable to that of its neutral polymer .
the chain stiffness influences both the local and the global chain structures .
a flexible chain exhibits a zigzagged local structure in the presence of salt ions and the condensed structure is a disordered , random globule .
a semiflexible chain is locally smooth , and the condensed structure is orderly packed , taking a form such as hairpin or toroid .
moreover , the chain stiffness can also affect the nature of the coil - globule transition .
the transition is occurred in a discrete manner for semiflexible chain , whereas in a continuous way for flexible chain .
this discrete feature is happened not only at low salt concentration when a semiflexible chain is collapsed , but also at high salt concentration when the collapsed chain is reexpanded .
at the end ,....
And you have already written the first three sentences of the full article: there is a resurgent interest in studying the properties of polyelectrolytes in multivalent salt solutions because such system reveals many fascinating phenomena .
one vital example is the dna condensation , in which dna , a negatively - charged polyelectrolyte , undergoes a dramatic condensation from an extended structure to a compact , highly - ordered structure while multivalent salt is added to the solution @xcite .
the condensation induced by multivalent salt is not a privilege reserved only for dna but a common feature of polyelectrolytes @xcite ..
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usually trivalent salts or charged molecules of higher valence are demanded to induce the condensation @xcite .
experiments have shown that the morphology of the condensate depends strongly on the chain bending rigidity which balances the attractive collapsing force at a solvent quality .
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10,389 |
Suppose that you have an abstract for a scientific paper: in this study , we have investigated the photoionization cross section of an on - center hydrogenic impurity in a multi - layered spherical quantum dot .
the electronic energy levels and their wave functions have been determined fully numerically by shooting method .
also , we have calculated the binding energy of the impurity by using these energy values .
the photoionization cross section has also been computed as a function of the layer thickness and normalized photon energies .
we have discussed in detail the possible physical reasons behind the changes in the binding energies and photoionization cross section . it is observed that both the binding energies and the photoionization cross sections depend strongly on the layer thickness and photon energies . .
And you have already written the first three sentences of the full article: an ionization process is removal of one or more electrons from a quantum system , such as atom , molecule , quantum heterostructure etc .
, in any manners .
if the ionization process is induced by a photon , this process is called photoionization ..
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the photoionization of atomic systems provides the opportunity to investigate the dynamic interplay among many body electron - electron correlations and relativistic effects.@xcite it is the simplest process giving detailed information on the atomic and molecular structure.@xcite numerous experimental and theoretical studies on photoionization cross section of different atoms have been published by many authors.@xcite photoionization cross sections are of great significance due to its numerous applications in space research , astrophysics , radiation protection , laser designing , controlled thermonuclear research and different types of laboratory plasma.@xcite on the other hand , because quantum dot ( qd ) heterostructures exhibit atomic properties such as energy levels , density of states etc .
, they are called as artificial atoms.@xcite the investigation of photoionization cross section of a hydrogenic impurity in a qd is very important especially for different optoelectronic device applications such as quantum dot infrared photodetectors .
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10,390 |
Suppose that you have an abstract for a scientific paper: we present high sensitivity polarimetric observations ( @xmath0mjy ) in 6 bands covering the @xmath1ghz range of a complete sample of 53 compact extragalactic radio sources brighter than @xmath2mjy at @xmath3ghz .
the observations , carried out with the australia telescope compact array ( atca ) , achieved a @xmath4 detection rate ( at @xmath5 ) . within this frequency range the spectra of about @xmath6 of sources
are well fitted by double power laws , both in total intensity and in polarisation , but the spectral shapes are generally different in the two cases .
most sources were classified as either steep or peaked spectrum but less than @xmath7 have the same classification in total and in polarised intensity .
no significant trends of the polarisation degree with flux density or with frequency were found .
the mean variability index in total intensity of steep - spectrum sources increases with frequency for a @xmath8 year lag , while no significant trend shows up for the other sources and for the 8 year lag . in polarisation ,
the variability index , that could be computed only for the @xmath9 year lag , is substantially higher than in total intensity and has no significant frequency dependence .
[ firstpage ] galaxies : active radio continuum : galaxies polarisation . .
And you have already written the first three sentences of the full article: at high radio frequencies ( @xmath10ghz ) the bright ( @xmath11mjy ) extragalactic radio population is dominated by blazars ( bl lacs and flat - spectrum radio quasars , fsrqs ) , interpreted as sources whose relativistic jets are directed very close to the line - of - sight ( see , e.g. , blandford & knigl 1979 ) .
the jets are collimated by intense magnetic fields .
the blazar radio emission is synchrotron radiation from a series of blobs along the jet ..
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the observed flux densities are blue - shifted and greatly boosted by relativistic effects . in this scenario ,
the flat radio spectra are interpreted as the combination of components self - absorbed up to different frequencies .
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10,391 |
Suppose that you have an abstract for a scientific paper: density perturbations generated from inflation almost always have a spectral index @xmath0 which runs ( varies with the wavelength ) .
we explore a running spectral index scenario in which the scalar spectral index runs from blue ( @xmath1 ) on large length scales to red ( @xmath2 ) on short length scales . specifically , we look for a correlation between the length scale at which @xmath3 and the length scale at which tensor to scalar ratio @xmath4 reaches a minimum for single field slow roll inflationary models . by computing the distribution of length scale ratios ,
we conclude that there indeed is a new approximate consistency condition that is characteristic of running spectral index scenarios that run from blue to red .
specifically , with strong running , we expect 96% of the slow roll models to have the two length scales to be within a factor of 2 , with the length scale at which the tensor to scalar ratio reaching a minimum longer than the wavelength at which @xmath3 . .
And you have already written the first three sentences of the full article: it is currently widely accepted that inflationary cosmological scenarios offer most promising explanations for the initial conditions for structure formation in our universe .
almost all inflationary scenarios predict that the primordial density perturbation spectrum deviates slightly from a power law and is dominated by scalar density fluctuations .
typically , the scalar density perturbation spectrum is parameterized as @xmath5 where @xmath6 is a scale dependent function which is usually called the running ( scalar ) spectral index ( running refers to the change in the spectral index as a function of wavenumber @xmath7 ) . combining observations of cmb , galaxy surveys , and ly@xmath8 forest , there have been claims for evidence of strongly running spectral index ( see e.g. @xcite ) , but at the moment , combined data set favors no spectral index running ( e.g. @xcite ) . nonetheless , a significant running of the spectral index is still a debatable possibility that will be settled by future experiments . according to the cmb and 2dfgrs galaxy survey data @xcite , @xmath9 furthermore ,.
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as pointed out by @xcite , within the context of single field inflationary models , there is some indication that the spectral index quantity @xmath10 runs from positive values ( blue ) on long length scales to negative values ( red ) on short length scales ( positive to negative within about 5 e - folds ) .
it is well known @xcite that one robust check of slow roll inflationary scenario is what is usually referred to as the single field self - consistency condition @xmath11 where @xmath12 is the spectral index of tensor perturbation power spectrum parameterized as @xmath13 and @xmath14 is the slow roll parameter characterizing the tensor to scalar power spectrum ratio . in @xcite , it was pointed out that if running occurs from blue to red , then there may be another approximate consistency condition that we may observationally aim at checking regarding inflationary scenarios .
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10,392 |
Suppose that you have an abstract for a scientific paper: using both halo model calculations and a large sample of simulated sz maps , we demonstrate that high - mass clusters add significant non - gaussian variance to measurements of the sz power spectrum amplitude .
the difficulty in correctly accounting theoretically for the contribution of these objects to the uncertainty in @xmath0 leads to a reduced sensitivity to @xmath1 .
we show that a simple solution is to mask out the brightest clusters in the map before measuring the power spectrum .
we demonstrate that fairly conservative masking can reduce the variance and gaussianize the statistics significantly , thus increasing the sensitivity to cosmological parameters . choosing which objects to mask is non - trivial ; we found that using a fixed sky density produced a well - defined and well - behaved estimate that can easily be applied to real maps .
for example , masking the 10 ( 90 ) brightest clusters in a 100 deg@xmath2 sz map will improve the sensitivity to @xmath0 by a factor of two at @xmath3 ( 2000 ) and 1.5 at @xmath4 ( 4000 ) .
we show that even in the presence of astrophysical foregrounds ( primary cmb and point sources ) and instrument noise , one can increase the precision on measurements of @xmath1 by masking up to 0.9 clusters deg@xmath5 . .
And you have already written the first three sentences of the full article: the sunyaev - zeldovich ( sz ) effect has long been recognized as a powerful tool for probing the physics of the intra - cluster medium , large - scale structure formation and the dark energy equation of state @xcite .
simple but robust analytical arguments @xcite and hydrodynamical simulations of clusters @xcite have indicated that the integrated sz flux ( the integral of the temperature decrement across the surface area of a cluster ) should correlate tightly with cluster mass .
combined with a greater sensitivity than optical or x - ray surveys to high redshift objects , this makes sz - selected cluster samples well suited for measuring the evolution of the cluster mass function over a wide range in redshift ..
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experiments such as the atacama cosmology telescope @xcite and the south pole telescope @xcite are currently surveying the microwave sky to develop large catalogs of galaxy clusters that are uniformly selected by the sz flux .
however , in order to use cluster samples for this purpose , it is necessary to have a good understanding of both the selection function of the survey @xcite and of the mapping between the measured integrated sz flux and cluster mass ( and how this evolves with redshift ) . besides the slope and normalization of the flux - mass ( y - m ) relation
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10,393 |
Suppose that you have an abstract for a scientific paper: many networks exhibit the small - world property of the neighborhood connectivity being higher than in comparable random networks .
however , the standard measure of local neighborhood clustering is typically not defined if a node has one or no neighbor . in such cases , local clustering
has traditionally been set to zero and this value influenced the global clustering coefficient .
such a procedure leads to under - estimation of the neighborhood clustering in sparse networks .
we propose to include @xmath0 as the proportion of leafs and isolated nodes to estimate the contribution of these cases and provide a formula for estimating a clustering coefficient excluding these cases from the watts & strogatz @xcite definition of the clustering coefficient . excluding leafs and isolated nodes leads to values which are up to 140% higher than the traditional values for the observed networks indicating that neighborhood connectivity is normally underestimated .
we find that the definition of the clustering coefficient has a major effect when comparing different networks . for metabolic networks of 43 organisms ,
relations changed for 58% of the comparisons
when a different definition was applied .
we also show that the definition influences small - world features and that the classification can change from non - small - world to small - world network .
we discuss the use of an alternative measure , disconnectedness @xmath1 , which is less influenced by leafs and isolated nodes . .
And you have already written the first three sentences of the full article: many real - world networks show properties of small - world networks as their neighborhood connectivity , generally denoted by the clustering coefficient , is higher than in comparable random networks@xcite .
the local clustering coefficient for an individual node @xmath2 with @xmath3 neighbors and @xmath4 edges between its neighbors is @xmath5 this formula is basically not defined if the number of neighbors @xmath3 becomes zero or one as the denominator becomes zero @xcite .
these cases are usually treated as @xmath6 although some authors also set these values to one @xcite . in the current scheme.
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, these values would be part of the global calculation @xmath7 in addition , we tested an alternative and more widely used definition of the clustering coefficient @xcite in which @xmath8 this might lead to biased assessments of neighborhood clustering in the sense that values that are not defined ( division by zero ) should not be included in the averaging .
thus , instead of using @xmath9 as the number of evaluated nodes for the global @xmath10 , a new number @xmath11 indicating all nodes with defined local clustering should be used for a global measure @xmath12 .
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10,394 |
Suppose that you have an abstract for a scientific paper: the timescale of quasar variability is widely expected to show the effects of time dilation . in this paper
we analyse the fourier power spectra of a large sample of quasar light curves to look for such an effect .
we find that the timescale of quasar variation does not increase with redshift as required by time dilation .
possible explanations of this result all conflict with widely held consensus in the scientific community . .
And you have already written the first three sentences of the full article: time dilation is a fundamental property of an expanding universe . in fact the increase of timescale by a factor of @xmath0 represents a basic link between redshift and time which is essentially related to the definition of time and is independant of cosmological model parameters . as a consequence , time dilation has generally been assumed to be a property of the universe even though it has proved hard to measure directly .
recently there has been new interest in time dilation as a result of experiments where its effect is large and must be taken into account .
there have been a number of claims by groups working on gamma ray bursters @xcite that time dilation is seen in the stretching of peak - to - peak timescales ..
Please generate the next two sentences of the article
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this has then been used to support the argument that the bursts are at cosmological distances .
it is not clear however that the argument can be inverted to provide convincing evidence for the existence of time dilation .
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10,395 |
Suppose that you have an abstract for a scientific paper: a physical model of geant4-based simulation of galactic cosmic ray ( gcr ) particles interaction with the lunar surface matter has been developed to investigate the production rate of cosmogenic nuclei . in this model
the gcrs , mainly very high energy protons and @xmath0 particles , bombard the surface of the moon and produce many secondary particles such as protons and neutrons .
the energies of proton and neutron at different depths are recorded and saved into root files , and the analytical expressions for the differential proton and neutron fluxes are obtained through the best - fit procedure under the root software . to test the validity of this model
, we calculate the production rates of long - lived nuclei @xmath1be and @xmath2al in the apollo 15 long drill core by combining the above differential fluxes and the newly evaluated spallation reaction cross sections .
numerical results show that the theoretical production rates agree quite well with the measured data .
it means that this model works well .
therefore , it can be expected that this model can be used to investigate the cosmogenic nuclei in lunar samples returned by chinese lunar exploration program and can be extended to study other objects , such as the meteorites and the earth s atmosphere . .
And you have already written the first three sentences of the full article: galactic cosmic rays ( gcrs ) are high energy particles that pass through the interstellar space in our milky way galaxy .
the most abundant components of gcrs are protons and @xmath0 particles .
these energetic particles can interact with the matters both in the interstellar space and interplanetary space ..
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the former can be used to investigate the origin and evolution of gcr itself@xcite , and the latter provide us an useful tool to investigate the cosmic ray exposure history of extraterrestrial bodies such as the planets and the meteorites@xcite . among these bodies
the moon is an unique one in our solar system . due to the atmosphere
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10,396 |
Suppose that you have an abstract for a scientific paper: we compute the leading corrections to the properties of w and z bosons induced at the one - loop level in the su(5)/so(5 ) littlest higgs model with t parity , and perform a global fit to precision electroweak data to determine the constraints on the model parameters .
we find that a large part of the model parameter space is consistent with data .
values of the symmetry breaking scale @xmath0 as low as 500 gev are allowed , indicating that no significant fine tuning in the higgs potential is required .
we identify a region within the allowed parameter space in which the lightest t - odd particle , the partner of the hypercharge gauge boson , has the correct relic abundance to play the role of dark matter .
in addition , we find that a consistent fit to data can be obtained for large values of the higgs mass , up to 800 gev , due to the possibility of a partial cancellation between the contributions to the @xmath1 parameter from higgs loops and new physics .
hep - ph/0506042 + .5 cm * electroweak precision constraintson the littlest higgs model .3 cm with t parity * .2 cm * jay hubisz , patrick meade , andrew noble , maxim perelstein * + _ institute for high energy phenomenology , + f.r .
newman laboratory of elementary particle physics , + cornell university , ithaca , ny 14853 , usa _
+ 0.3truecm .
And you have already written the first three sentences of the full article: the mechanism of electroweak symmetry breaking ( ewsb ) remains the most pressing puzzle in elementary particle physics .
experimentally , this question will be addressed at the large hadron collider ( lhc ) . theoretically , several interesting possibilities have been proposed . in this article , we will concentrate on the `` little higgs '' proposal @xcite . in this approach ,
the higgs emerges as a pseudo - nambu - goldstone boson , whose properties are constrained by global symmetries ..
Please generate the next two sentences of the article
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these global symmetries are not exact , and their breaking allows the higgs to participate in non - derivative ( i.e. gauge and yukawa ) interactions .
at the same time , there is enough global symmetry left to ensure that the higgs mass term vanishes at tree level , and is only logarithmically sensitive to the unknown short distance ( ultraviolet , or uv ) physics at the one - loop level .
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10,397 |
Suppose that you have an abstract for a scientific paper: we calculate the branching ratio and direct cp asymmetry in nonleptonic two body @xmath0 decays @xmath1 . it is shown that the tree diagram and gluon fusion mechanism via penguin diagram have comparable contributions to these decays which , as a result , could provide an interesting venue for investigating cp violation .
our estimate shows that the direct cp asymmetry in the above decays could be as large as @xmath2 which along with a branching ratio @xmath3 should be accessible to experiment in the near future .
the discovery by the cleo collaboration of a larger than expected branching ratio for fast @xmath4 production in hadronic @xmath0 decays@xcite has led to extensive theoretical work on investigating the underlying mechanism .
one explanation which is based on the gluon - gluon-@xmath4 anomalous coupling , has been proposed by atwood and soni@xcite . in this mechanism , @xmath4 is produced by the fragmentation of the virtual gluon of the qcd @xmath5 penguin .
on the other hand , in order to formulate the inclusive @xmath6 and exclusive @xmath7 decays under the same mechanism , we proposed a nonspectator gluon fusion process using anomaly driven @xmath8 vertex@xcite .
the exclusive branching ratio @xmath9 obtained this way is in good agreement with experimantal data . in this paper , we focus on a different hadronic decay mode of @xmath0 mesons which may receive a significant contribution from the above mechanism .
indeed , if the anomalous @xmath8 vertex in conjunction with the qcd penguin is the underlying process for the fast @xmath4 production in @xmath0 meson decays , one could expect that the same mechanism also be an important part of the two body @xmath1 decay modes . the difference between these decay modes and @xmath7
decay is in that , unlike the latter one , the former decays receive a comparable contribution from the tree diagrams . as a result
, one could expect that the above decay modes provide a suitable avenue to investigate the direct cp asymmetry in charged....
And you have already written the first three sentences of the full article: the authors thank professors i. a. sanda and a. soni for useful discussions .
m. a. acknowledges support from the science and technology agency of japan .
e. k. acknowledges support from the japanese society for the promotion of science ..
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3.0 cm * figure 1 * : non - spectator contribution to @xmath99 decays .
+ 0.5 cm * figure 2 * : the current - current ( tree ) contribution to @xmath42 decay .
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10,398 |
Suppose that you have an abstract for a scientific paper: a few type ia supernovae ( sne ia ) have been suggested to be an explosion of a super - chandrasekhar - mass white dwarf ( wd ) to account for their large luminosities , requiring a large amount of @xmath0ni .
however , the candidate over - luminous sne ia 2003fg , 2006gz , and ( moderately over - luminous ) sn 1991 t , have very different observational features : the characteristic time - scale and velocity are very different . we examine if and how the diversity can be explained , by 1d _ spherical _ radiation transport calculations covering a wide range of model parameters ( e.g. , wd mass ) . the observations of sn 2006gz are naturally explained by the super - chandrasekhar - mass model .
sn 1991 t represents a marginal case , which may either be a chandrasekhar or a super - chandrasekhar - mass wd explosion . on the other hand ,
the low velocity and short time - scale seen in sn 2003fg indicate that the ejecta mass is smaller than the chandrasekhar - mass , which is an apparent contradiction to the large luminosity .
we suggest that the problem is solved if the progenitor wd , and thus the sn explosion , is aspherical .
this may reflect a rapid rotation of the progenitor star , likely a consequence of the super - chandrasekhar - mass wd progenitor .
the observed differences between sne 2003fg and 2006gz may be attributed to different viewing orientations .
[ firstpage ] white dwarfs radiative transfer supernovae : individual ( sn 2006gz , sn 2003fg , sn 1991 t ) .
And you have already written the first three sentences of the full article: type ia supernovae ( sne ia ) are currently the most mature cosmological distance indicator which led to the discovery of the acceleration of the universe ( riess et a. 1998 ; perlmutter et al .
their use as distance indicators relies on the well calibrated light curve characteristics , namely a phenomenological relation between the peak luminosity and the light curve width ( `` phillips relation '' or `` stretching factor '' ; phillips 1993 ; perlmutter et al . 1997 ; phillips et al .
1999 ) . by clarifying natures of progenitor system(s ) of sne ia ( livio 2000 : hillebrandt & niemeyer 2000 ; nomoto et al . 2003 ).
Please generate the next two sentences of the article
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, one expects to obtain deep knowledge on the origin of the light curve relation for the better luminosity calibration , as well as new application of sne ia to a range of cosmological study . a progenitor of normal sne ia ( branch et al .
1993 ; li et al .
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10,399 |
Suppose that you have an abstract for a scientific paper: we present a theoretical analysis of exciton transfer and decoherence effects in a photosynthetic dimer interacting with collective ( correlated ) and local ( uncorrelated ) protein - solvent environments .
our approach is based on the framework of the spin - boson model .
we derive explicitly the thermal relaxation and decoherence rates of the exciton transfer process , valid for arbitrary temperatures and for arbitrary ( in particular , large ) interaction constants between the dimer and the environments .
we establish a generalization of the marcus formula , giving reaction rates for dimer levels possibly individually and asymmetrically coupled to environments .
we identify rigorously parameter regimes for the validity of the generalized marcus formula .
the existence of long living quantum coherences at ambient temperatures emerges naturally from our approach .
la - ur-15 - 29509 .
And you have already written the first three sentences of the full article: when a sunlight photon is absorbed by a light - sensitive molecule ( such as chlorophyll or carotenoid ) in a light - harvesting photosynthetic complex ( lhc ) , the photon energy is stored in the molecule in the form of an exciton , an excited electron state of the molecule .
the exciton then travels very quickly ( some picoseconds ) inside the lhc and reaches the reaction center ( rc ) , where charge separation , and afterwards relatively slow chemical reactions take place @xcite .
both the primary processes of exciton dynamics and charge separation occur in the presence of a protein ( and solvent ) environment at ambient temperature . in the framework of frster s resonance excitation transfer theory @xcite.
Please generate the next two sentences of the article
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, the energy transfer is so fast that both fluorescence and recombination ( due to the environment ) can be neglected . when modeling these primary exciton transfer ( et ) processes , the light - sensitive molecule is usually associated with a geometrically localized site , @xmath0 , having excited electron energy @xmath1 @xcite .
the total number of sites , @xmath2 , depends on the photosynthetic system .
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