Instruction: what is the prompt that generates the input?

Input: Technological innovation has extensively been studied to make firmssustainable and more competitive. Within this context, the most importantrecent issue has been the dynamics of collaborative innovation among firms. Wetherefore investigated a patent network, especially focusing on its spatialcharacteristics. The results can be summarized as follows. (1) The degreedistribution in a patent network follows a power law. A firm can then beconnected to many firms via hubs connected to the firm. (2) The neighbors'average degree has a null correlation, but the clustering coefficient has anegative correlation. The latter means that there is a hierarchical structureand bridging different modules may shorten the paths between the nodes in them.(3) The distance of links not only indicates the regional accumulations offirms, but the importance of time it takes to travel, which plays a key role increating links. (4) The ratio of internal links in cities indicates that wehave to consider the existing links firms have to facilitate the creation ofnew links.


Instruction: what is the prompt that generates the input?

Input: The spin-Hall effect in the two-dimensional electron gas (2DEG) generatessymmetric out-of-plane spin Sz accumulation about the current axis in theabsence of external magnetic field. Here we employ the real spaceLandauer-Keldysh formalism [B. K. Nikolic et al., Phys. Rev. Lett. 95, 046601(2005); Phys. Rev. B 73, 075303 (2006)] by considering a four-terminal setup toinvestigate the circumstances in which this symmetry is broken. For the absenceof Dresselhaus interaction, starting from the applied out-of-plane Bcorresponding to Zeeman splitting energy 0 - 0.5 times the Rashba hoppingenergy tR, the breaking process is clearly seen. The influence of the Rashbainteraction on the magnetization of the 2DEG is studied herein. For coexistedRashba tR and Dresselhaus tD spin-orbit couplings in the absence of B,interchanging tR and tD reverses the entire accumulation pattern.


Instruction: what is the prompt that generates the input?

Input: We study in general the time-evolution of correlation functions in a extendedquantum system after the quench of a parameter in the hamiltonian. We show thatcorrelation functions in d dimensions can be extracted using methods ofboundary critical phenomena in d+1 dimensions. For d=1 this allows to use thepowerful tools of conformal field theory in the case of critical evolution.Several results are obtained in generic dimension in the gaussian (mean-field)approximation. These predictions are checked against the real-time evolution ofsome solvable models that allows also to understand which features are validbeyond the critical evolution.  All our findings may be explained in terms of a picture generally valid,whereby quasiparticles, entangled over regions of the order of the correlationlength in the initial state, then propagate with a finite speed through thesystem. Furthermore we show that the long-time results can be interpreted interms of a generalized Gibbs ensemble. We discuss some open questions andpossible future developments.


Instruction: what is the prompt that generates the input?

Input: Instead of using local field equations - like the Dirac equation for spin-1/2and the Klein-Gordon equation for spin-0 particles - one could try to usenon-local field equations in order to describe scattering processes. The latterequations can be obtained by means of the relativistic energy together with thecorrespondence principle, resulting in equations with a square root operator.By coupling them to an electromagnetic field and expanding the square root (andtaking into account terms of quadratic order in the electromagnetic couplingconstant e), it is possible to calculate scattering matrix elements within theframework of quantum electrodynamics, e.g. like those for Compton scattering orfor the scattering of two identical particles. This will be done here for thescalar case. These results are then compared with the corresponding ones basedon the Klein-Gordon equation. A proposal of how to transfer these reflectionsto the spin-1/2 case is also presented.


Instruction: what is the prompt that generates the input?

Input: We study the pseudospectrum of a class of non-selfadjoint differentialoperators. Our work consists in a detailed study of the microlocal properties,which rule the spectral stability or instability phenomena appearing undersmall perturbations for elliptic quadratic differential operators. The class ofelliptic quadratic differential operators stands for the class of operatorsdefined in the Weyl quantization by complex-valued elliptic quadratic symbols.We establish in this paper a simple necessary and sufficient condition on theWeyl symbol of these operators, which ensures the stability of their spectra.When this condition is violated, we prove that it occurs some strong spectralinstabilities for the high energies of these operators, in some regions whichcan be far away from their spectra. We give a precise geometrical descriptionof them, which explains the results obtained for these operators in somenumerical simulations giving the computation of false eigenvalues far fromtheir spectra by algorithms for eigenvalues computing.


Instruction: what is the prompt that generates the input?

Input: A cascade model is described based on multiplier distributions determinedfrom 3D direct numerical simulations (DNS) of turbulent particle laden flows,which include two-way coupling between the phases at global mass loadings equalto unity. The governing Eulerian equations are solved using pseudo-spectralmethods on up to 512**3 computional grid points. DNS results for particleconcentration and enstrophy at Taylor microscale Reynolds numbers in the range34 - 170 were used to directly determine multiplier distributions (PDFs) onspatial scales 3 times the Kolmogorov length scale. The width of the PDFs,which is a measure of intermittency, decreases with increasing mass loadingwithin the local region where the multipliers are measured. The functional formof this dependence is not sensitive to Reynolds numbers in the rangeconsidered. A partition correlation probability is included in the cascademodel to account for the observed spatial anticorrelation between particleconcentration and enstrophy. Joint probability distribution functions ofconcentration and enstrophy generated using the cascade model are shown to bein excellent agreement with those derived directly from our 3D simulations.Probabilities predicted by the cascade model are presented at Reynolds numberswell beyond what is achievable by direct simulation. These results clearlyindicate that particle mass loading significantly reduces the probabilities ofhigh particle concentration and enstrophy relative to those resulting fromunloaded runs. Particle mass density appears to reach a limit at around 100times the gas density. This approach has promise for significant computationalsavings in certain applications.


Instruction: what is the prompt that generates the input?

Input: We study the expansion of the nearby Universe using a sample of Type Iasupernovae at redshifts below 0.08. These supernovae allow peculiar velocitiesto be measured at unprecedented precision. We have investigated in detail thepossibility of a varying Hubble constant with redshift and found no evidence ofa monopole term for the nearby Universe. A large scale streaming motion isfound at an amplitude of about $340^{63}_{-71}$ km/sec, aligned in thedirection of $(l_0, b_0) = (312^{\rm o}.0^{13.5}_{-7.4}, 25^{\rmo}.7^{8.0}_{-9.2})$, which is close to the direction of the center of Shapleysupercluster of galaxies. The large scale streaming motion is best fit by afunction involving a strong bipolar term. The streaming velocity field extendsfrom the lowest redshift ($\sim 0.007$) to beyond 0.025 and likely out to evenhigher redshifts. The velocity field at redshift below 0.01 can be equally welldescribed by a dipole field or by the same bipolar streaming velocity fieldthat reaches out to beyond $z \sim 0.025$. We are also able to deduce a robustestimate of the random velocity component of the peculiar velocity field.Within the volume of redshift below 0.01 (weighted average redshift of $\sim$0.067), this thermal component is found to be about 270 km/sec. Aftercorrecting this smooth streaming motion, we are able to significantly improvethe Hubble expansion fits of these supernovae. The CMAGIC method gives adramatic decrease of $\chi^2$ from 90 to 63 for 69 degrees of freedom, andyields a residual scatter of only 0.12 magnitude; the maximum light methodgives also a moderate improvement.


Instruction: what is the prompt that generates the input?

Input: For a smooth projective curve, the cycles of e-secant k-planes are among themost studied objects in classical enumerative geometry and there are well-knownformulas due to Castelnuovo, Cayley and MacDonald concerning them. Despitevarious attempts, surprisingly little is known about the enumerative validityof such formulas. The aim of this paper is to completely clarify this problemin the case of the generic curve C of given genus. Using degenerationtechniques and a few facts about the birational geometry of moduli spaces ofstable pointed curves we determine precisely under which conditions the cycleof e-secant k-planes in non-empty and we compute its dimension. We alsoprecisely determine the dimension of the variety of linear series on C carryinge-secant k-planes. In a different direction, in the last part of the paper westudy the distribution of ramification points of the powers of a line bundle onC having prescribed ramification at a given point.


Instruction: what is the prompt that generates the input?

Input: Spatial associations have been found between interstellar neutral hydrogen(HI) emission morphology and small-scale structure observed by the WilkinsonMicrowave Anisotropy Probe (WMAP) in an area bounded by l = 60 & 180 deg, b =30 & 70 deg, which was the primary target for this study. This area is markedby the presence of highly disturbed local HI and a preponderance ofintermediate- and high-velocity gas. The HI distribution toward the brightestpeaks in the WMAP Internal Linear Combination (ILC) map for this area isexamined and by comparing with a second area on the sky it is demonstrated thatthe associations do not appear to be the result of chance coincidence. Closeexamination of several of the associations reveals important new properties ofdiffuse interstellar neutral hydrogen structure. In the case of high-velocitycloud MI, the HI and WMAP ILC morphologies are similar and an excess of softX-ray emission and H-alpha emission have been reported for this feature. It issuggested that the small angular-scale, high frequency continuum emissionobserved by WMAP may be produced at the surfaces of HI features interacting oneanother, or at the interface between moving HI structures and regions ofenhanced plasma density in the surrounding interstellar medium. It is possiblethat dust grains play a role in producing the emission. However, the primarypurpose of this report is to draw attention to these apparent associationswithout offering an unambiguous explanation as to the relevant emissionmechanism(s).


Instruction: what is the prompt that generates the input?

Input: We report on transcritical bifurcations of periodic orbits in non-integrabletwo-dimensional Hamiltonian systems. We discuss their existence criteria andsome of their properties using a recent mathematical description oftranscritical bifurcations in families of symplectic maps. We then presentnumerical examples of transcritical bifurcations in a class of generalizedH\'enon-Heiles Hamiltonians and illustrate their stabilities and unfoldingsunder various perturbations of the Hamiltonians. We demonstrate that forHamiltonians containing straight-line librating orbits, the transcriticalbifurcation of these orbits is the typical case which occurs also in theabsence of any discrete symmetries, while their isochronous pitchforkbifurcation is an exception. We determine the normal forms of both types ofbifurcations and derive the uniform approximation required to includetranscritically bifurcating orbits in the semiclassical trace formula for thedensity of states of the quantum Hamiltonian. We compute the coarse-graineddensity of states in a specific example both semiclassically and quantummechanically and find excellent agreement of the results.


Instruction: what is the prompt that generates the input?

Input: Past work has shown that ions can pass through a membrane more readily in onedirection than the other. We demonstrate here in a model and an experiment thatfor a mixture of small and large particles such asymmetric diffusion can arisesolely from an asymmetry in the geometry of the pores of the membrane. Ourdeterministic simulation considers a two-dimensional gas of elastic disks oftwo sizes diffusing through a membrane, and our laboratory experiment examinesthe diffusion of glass beads of two sizes through a metal membrane. In bothexperiment and simulation, the membrane is permeable only to the smallerparticles, and the asymmetric pores lead to an asymmetry in the diffusion ratesof these particles. The presence of even a small percentage of large particlescan clog a membrane, preventing passage of the small particles in one directionwhile permitting free flow of the small particles in the other direction. Thepurely geometric kinetic constraints may play a role in common biologicalcontexts such as membrane ion channels.


Instruction: what is the prompt that generates the input?

Input: We evaluate the possibility of observable effects arising from collisionsbetween vacuum bubbles in a universe undergoing false-vacuum eternal inflation.Contrary to conventional wisdom, we find that under certain assumptions mostpositions inside a bubble should have access to a large number of collisionevents. We calculate the expected number and angular size distribution of suchcollisions on an observer's "sky," finding that for typical observers thedistribution is anisotropic and includes many bubbles, each of which willaffect the majority of the observer's sky. After a qualitative discussion ofthe physics involved in collisions between arbitrary bubbles, we evaluate theimplications of our results, and outline possible detectable effects. In anoptimistic sense, then, the present paper constitutes a first step in anassessment of the possible effects of other bubble universes on the cosmicmicrowave background and other observables.


Instruction: what is the prompt that generates the input?

Input: We present the first detailed study of the properties (temperatures,gravities, and masses) of the NGC 6791 white dwarf population. This uniquestellar system is both one of the oldest (8 Gyr) and most metal-rich ([Fe/H] ~0.4) open clusters in our Galaxy, and has a color-magnitude diagram (CMD) thatexhibits both a red giant clump and a much hotter extreme horizontal branch.Fitting the Balmer lines of the white dwarfs in the cluster, using Keck/LRISspectra, suggests that most of these stars are undermassive, <M> = 0.43 +/-0.06 Msun, and therefore could not have formed from canonical stellar evolutioninvolving the helium flash at the tip of the red giant branch. We show that atleast 40% of NGC 6791's evolved stars must have lost enough mass on the redgiant branch to avoid the flash, and therefore did not convert helium intocarbon-oxygen in their core. Such increased mass loss in the evolution of theprogenitors of these stars is consistent with the presence of the extremehorizontal branch in the CMD. This unique stellar evolutionary channel alsonaturally explains the recent finding of a very young age (2.4 Gyr) for NGC6791 from white dwarf cooling theory; helium core white dwarfs in this clusterwill cool ~3 times slower than carbon-oxygen core stars and therefore thecorrected white dwarf cooling age is in fact ~7 Gyr, consistent with the wellmeasured main-sequence turnoff age. These results provide direct empiricalevidence that mass loss is much more efficient in high metallicity environmentsand therefore may be critical in interpreting the ultraviolet upturn inelliptical galaxies.


Instruction: what is the prompt that generates the input?

Input: The physical characteristics of the Lyman-alpha forest cloud systems arecombined with observations on the baryonic mass density of the Universe andconstraints from primordial nucleosynthesis to set boundary conditions on theIntergalactic Medium (IGM) at the epoch of z=2.5. The Universe is considered aclosed system and allowed to expand adiabatically from the epoch when QSOsfirst ionized the IGM (5 <= z_on <= 20). The average kinetic energy of a gas iscalculated in the region where the gas transitions from relativistic tonon-relativistic behavior. All of the above measurements are then used todetermine the thermal history of the IGM in the redshift range 2.5 <= z <=z_on. The hot IGM is assumed to inverse Compton scatter photons from the CosmicMicrowave Background (CMBR) and consequently distort the CMBR as seen at thepresent epoch. The temperature of the IGM at z=2.5 and the epoch z_on areadjusted, within the constraints defined above, to give the best overallagreement with published data on the temperature of the IGM. We find that themodel of the IGM proposed here does not grossly distort the CMBR, and in factagrees quite closely with the preliminary results from the Cosmic BackgroundExplorer (COBE) satellite. However, our model of the IGM cannot explain theobserved cosmic x ray background.  This paper was originally written in 1990. It was never submitted forpublication.


Instruction: what is the prompt that generates the input?

Input: Arguments showing that exchange-only optimized effective potential (xOEP)methods, with finite basis sets, cannot in general yield the Hartree-Fock (HF)ground state energy, but a higher one, are given. While the orbital products ofa complete basis are linearly dependent, the HF ground state energy can only beobtained via a basis set xOEP scheme in the special case that all products ofoccupied and unoccupied orbitals emerging from the employed orbital basis setare linearly independent from each other. In this case, however, exchangepotentials leading to the HF ground state energy exhibit unphysicaloscillations and do not represent a Kohn-Sham (KS) exchange potential. Thesefindings solve the seemingly paradoxical results of Staroverov, Scuseria andDavidson that certain finite basis set xOEP calculations lead to the HF groundstate energy despite the fact that within a real space (or complete basis)representation the xOEP ground state energy is always higher than the HFenergy. Moreover, whether or not the occupied and unoccupied orbital productsare linearly independent, it is shown that basis set xOEP methods onlyrepresent exact exchange-only (EXX) KS methods, i.e., proper density-functionalmethods, if the orbital basis set and the auxiliary basis set representing theexchange potential are balanced to each other, i.e., if the orbital basis iscomprehensive enough for a given auxiliary basis. Otherwise xOEP methods do notrepresent EXX KS methods and yield unphysical exchange potentials.


Instruction: what is the prompt that generates the input?

Input: We construct a family of equations of state within a quasiparticle model byrelating pressure, energy density, baryon density and susceptibilities adjustedto first-principles lattice QCD calculations. The relation between pressure andenergy density from lattice QCD is surprisingly insensitive to details of thesimulations. Effects from different lattice actions, quark masses and latticespacings used in the simulations show up mostly in the quark-hadron phasetransition region which we bridge over by a set of interpolations to a hadronresonance gas equation of state. Within our optimized quasiparticle model wethen examine the equation of state along isentropic expansion trajectories atsmall net baryon densities, as relevant for experiments and hydrodynamicsimulations at RHIC and LHC energies. We illustrate its impact on azimuthalflow anisotropies and transverse momentum spectra of various hadron species.


Instruction: what is the prompt that generates the input?

Input: This paper focuses on supergravity duals of BPS states in N=4 superYang-Mills. In order to describe these duals, we begin with a sequence ofbreathing mode reductions of IIB supergravity: first on S^3, then S^3 x S^1,and finally on S^3 x S^1 x CP^1. We then follow with a complete supersymmetryanalysis, yielding 1/8, 1/4 and 1/2 BPS configurations, respectively (where inthe last step we take the Hopf fibration of S^3). The 1/8 BPS geometries, whichhave an S^3 isometry and are time-fibered over a six-dimensional base, aredetermined by solving a non-linear equation for the Kahler metric on the base.Similarly, the 1/4 BPS configurations have an S^3 x S^1 isometry and afour-dimensional base, whose Kahler metric obeys another non-linear,Monge-Ampere type equation.  Despite the non-linearity of the problem, we develop a universal bubbling AdSdescription of these geometries by focusing on the boundary conditions whichensure their regularity. In the 1/8 BPS case, we find that the S^3 cycleshrinks to zero size on a five-dimensional locus inside the six-dimensionalbase. Enforcing regularity of the full solution requires that the interior of asmooth, generally disconnected five-dimensional surface be removed from thebase. The AdS_5 x S^5 ground state corresponds to excising the interior of anS^5, while the 1/8 BPS excitations correspond to deformations (includingtopology change) of the S^5 and/or the excision of additional droplets from thebase. In the case of 1/4 BPS configurations, by enforcing regularityconditions, we identify three-dimensional surfaces inside the four-dimensionalbase which separate the regions where the S^3 shrinks to zero size from thosewhere the S^1 shrinks.


Instruction: what is the prompt that generates the input?

Input: We present new multicolor photo-polarimetry of stars behind the SouthernCoalsack. Analyzed together with multiband polarization data from theliterature, probing the Chamaeleon I, Musca, rho Opiuchus, R CrA and Taurusclouds, we show that the wavelength of maximum polarization (lambda_max) islinearly correlated with the radiation environment of the grains. UsingFar-Infrared emission data, we show that the large scatter seen in previousstudies of lambda_max as a function of A_V is primarily due to line of sighteffects causing some A_V measurements to not be a good tracer of the extinction(radiation field strength) seen by the grains being probed. The derived slopesin lambda_max vs. A_V, for the individual clouds, are consistent with a commonvalue, while the zero intercepts scale with the average values of the ratios oftotal-to-selective extinction (R_V) for the individual clouds. Within eachcloud we do not find direct correlations between lambda_max and R_V. Thepositive slope in consistent with recent developments in theory and indicatingalignment driven by the radiation field. The present data cannot conclusivelydifferentiate between direct radiative torques and alignment driven by H_2formation. However, the small values of lambda_max(A_V=0), seen in severalclouds, suggest a role for the latter, at least at the cloud surfaces. Thescatter in the lambda_max vs. A_V relation is found to be associated with thecharacteristics of the embedded Young Stellar Objects (YSO) in the clouds. Wepropose that this is partially due to locally increased plasma damping of thegrain rotation caused by X-rays from the YSOs.


Instruction: what is the prompt that generates the input?

Input: In this paper we present a new mathematical model for the density regionswhere a specific spectral line and its SACs/DACs are created in the Oe and Bestellar atmospheres. In the calculations of final spectral line function weconsider that the main reasons of the line broadening are the rotation of thedensity regions creating the spectral line and its DACs/SACs, as well as therandom motions of the ions. This line function is able to reproduce thespectral feature and it enables us to calculate some important physicalparameters, such as the rotational, the radial and the random velocities, theFull Width at Half Maximum, the Gaussian deviation, the optical depth, thecolumn density and the absorbed or emitted energy. Additionally, we cancalculate the percentage of the contribution of the rotational velocity and theions' random motions of the DACs/SACs regions to the line broadening. Finally,we present two tests and three short applications of the proposed model.


Instruction: what is the prompt that generates the input?

Input: We investigate the Gross-Pitaevskii equation for a classically chaoticsystem, which describes an atomic Bose-Einstein condensate confined in anoptical lattice and driven by a spatiotemporal periodic laser field. It isdemonstrated that the exact Floquet states appear when the externaltime-dependent potential is balanced by the nonlinear mean-field interaction.The balance region of parameters is divided into a phase-continuing region anda phase-jumping one. In the latter region, the Floquet states arespatiotemporal vortices of nontrivial phase structures and zero-density cores.Due to the velocity singularities of vortex cores and the blowing-up ofperturbed solutions, the spatiotemporal vortices are unstable periodic statesembedded in chaos. The stability and instability of these Floquet states arenumerically explored by the time evolution of fidelity between the exact andnumerical solutions. It is numerically illustrated that the stable Floquetstates could be prepared from the uniformly initial states by slow growth ofthe external potential.


Instruction: what is the prompt that generates the input?

Input: We utilize a recent formulation of a spherically symmetric spacetime endowedwith a general decomposition of the energy momentum tensor [Phys. Rev. D, 75,024031 (2007)] to derive equations governing spherically symmetricdistributions of electromagnetic matter. We show the system reduces to theReissner-Nordstrom spacetime in general, spherically symmetric coordinates inthe vacuum limit. Furthermore, we show reduction to the charged Vaidyaspacetime in non-null coordinates when certain equations of states are chosen.A model of gravitational collapse is discussed whereby a charged fluid resideswithin a boundary of finite radial extent on the initial hypersurface, and isallowed to radiate charged particles. Our formalism allows for the discussionof all regions in this model without the need for complicated matching schemesat the interfaces between successive regions. As further examples we considerthe collapse of a thin shell of charged matter onto a Reissner-Nordstrom blackhole. Finally, we reduce the entire system of equations to the static case suchthat we have the equations for hydrostatic equilibrium of a charged fluid.


Instruction: what is the prompt that generates the input?

Input: The 105-ms X-ray pulsar J1852+0040 is the central compact object (CCO) in SNRKes 79. We report a sensitive upper limit on its radio flux density of 12 uJyat 2 GHz using the NRAO GBT. Timing using XMM and Chandra over a 2.4 yr spanreveals no significant change in its spin period. The 2 sigma upper limit onthe period derivative leads, in the dipole spin-down formalism, to an energyloss rate E-dot < 7e33 ergs/s, surface magnetic field strength B_p < 1.5e11 G,and characteristic age tau_c = P/2P-dot > 8 Myr. This tau_c exceeds the age ofthe SNR by 3 orders of magnitude, implying that the pulsar was born spinning atits current period. However, the X-ray luminosity of PSR J1852+0040, L(bol) ~3e33(d/7.1 kpc)^2 ergs/s is a large fraction of E-dot, which challenges therotation-powered assumption. Instead, its high blackbody temperature,0.46+/-0.04 keV, small blackbody radius ~ 0.8 km, and large pulsed fraction, ~80%, may be evidence of accretion onto a polar cap, possibly from a fallbackdisk made of supernova debris. If B_p < 1e10 G, an accretion disk can penetratethe light cylinder and interact with the magnetosphere while resulting torqueson the neutron star remain within the observed limits. A weak B-field is alsoinferred in another CCO, the 424-ms pulsar 1E 1207.4-5209, from its steady spinand soft X-ray absorption lines. We propose this origin of radio-quiet CCOs:the B-field, derived from a turbulent dynamo, is weaker if the NS is formedspinning slowly, which enables it to accrete SN debris. Accretion excludesneutron stars born with both B_p < 1e11 G and P > 0.1 s from radio pulsarsurveys, where B_p < 1e11 G is not encountered except among very old (tau_c >40 Myr) or recycled pulsars. Finally, such a CCO, if born in SN 1987A, couldexplain the non-detection of a pulsar there.


Instruction: what is the prompt that generates the input?

Input: Order(N) Tight-Binding Molecular Dynamics (TBMD) simulations are performed toinvestigate the thermal stability of (10,10) metallic Single-Walled CarbonNanotubes (SWCNT). Periodic boundary conditions (PBC) are applied in axialdirection. Velocity Verlet algorithm along with the canonical ensemblemolecular dynamics (NVT) is used to simulate the tubes at the targetedtemperatures. The effects of slow and rapid temperature increases on thephysical characteristics, structural stability and the energetics of the tubeare investigated and compared. Simulations are carried out starting from roomtemperature and the temperature is raised in steps of 300K. Stability of thesimulated metallic SWCNT is examined at each step before it is heated to highertemperatures. First indication of structural deformation is observed at 600K.For higher heat treatments the deformations are more pronounced and the bondbreaking temperature is reached around 2500K. Gradual (slow) heating andthermal equilibrium (fast heating) methods give the value of radial thermalexpansion coefficient in the temperature range between 300K-600K as0.31x10^{-5}(1/K) and 0.089x10^{-5}(1/K), respectively. After 600K, bothmethods give the same value of 0.089x10^{-5}(1/K). The ratio of the totalenergy per atom with respect to temperature is found to be 3x10^{-4} eV/K.


Instruction: what is the prompt that generates the input?

Input: (Abridged) Using cosmological hydrodynamic simulations in combination withanalytic modeling, we show that the galaxy stellar mass-metallicity relation(MZR) provides strong constraints on galactic outflows across cosmic time. Wecompare three outflow models: No outflows, a "constant wind" (cw) model thatemulates the popular Dekel & Silk (1986) scenario, and a ``momentum-drivenwind" (vzw) model. We find that only the vzw scaling reproduces the observedz~2 MZR's slope, amplitude, and scatter. Comparing our fully three-dimensionalsimulations with a simple one-zone chemical evolution model, we find that theMZR can be understood in terms of three parameters: (1) The equilibriummetallicity Z_eq=y*SFR/ACC (where y=true yield), reflecting the enrichmentbalance between star formation rate SFR and gas accretion rate ACC; (2) thedilution time t_d=M_g/ACC, representing the timescale for a galaxy to return toZ_eq after a metallicity-perturbing interaction; and (3) the blowout massM_blowout, which is the galaxy stellar mass above which winds can escape itshalo. When outflows with mass loading factor MLF are present, galaxies belowM_blowout obey Z_eq = y/(1+MLF), while above M_blowout, Z_eq->y. Our cw modelhas M_blowout ~ 10^10 M_sun, which yields a sharp upturn in the MZR above thisscale and a flat MZR with large scatter below it, in strong disagreement withobservations. Our vzw model reproduces the observed Z_g \propto M_*^0.3 becauseZ_eq \propto MLF^-1 \propto M_*^1/3 when MLF >> 1 (i.e. at low masses). Theflattening of the MZR at M_* > 10^10.5 M_sun observed by Tremonti et al. (2004)reflects the mass scale where MLF~1, rather than a characteristic wind speed.The tight observed MZR scatter is ensured when t_d<1 dynamical time, which isonly satisified at all masses and epochs in our momentum-driven wind model.


Instruction: what is the prompt that generates the input?

Input: We present broadband NIR spectra of A0620-00 obtained with SpeX on the IRTF.The spectrum is characterized by a blue continuum on which are superimposedbroad emission lines of HI and HeII and a host of narrower absorption lines ofneutral metals and molecules. Spectral type standard star spectra scaled to thedereddened spectrum of A0620-00 in K exceed the A0620-00 spectrum in J and Hfor all stars of spectral type K7V or earlier, demonstrating that the donorstar, unless later than K7V, cannot be the sole NIR flux source in A0620-00. Inaddition, the atomic absorption lines in the K3V spectrum are too weak withrespect to those of A0620-00 even at 100% donor star contribution, restrictingthe spectral type of the donor star in A0620-00 to later than K3V. Comparisonof the A0620-00 spectrum to scaled K star spectra indicates that the COabsorption features are significantly weaker in A0620-00 than in field dwarfstars. Fits of scaled model spectra of a Roche lobe-filling donor star to thespectrum of A0620-00 show that the best match to the CO absorption lines isobtained when the C abundance is reduced to [C/H] = -1.5. The donor starcontribution in the H waveband is determined to be 82+-2%. Combined withprevious published results from Froning & Robinson (2001) and Marsh et al.(1994), this gives a precise mass for the black hole in A0620-00 of M_BH =9.7+-0.6 M_solar.


Instruction: what is the prompt that generates the input?

Input: There exist methods for determining effective conservative interactions incoarse grained particle based mesoscopic simulations. The resulting models canbe used to capture thermal equilibrium behavior, but in the model system westudy do not correctly represent transport properties. In this article wesuggest the use of force covariance to determine the full functional form ofdissipative and stochastic interactions. We show that a combination of theradial distribution function and a force covariance function can be used todetermine all interactions in dissipative particle dynamics. Furthermore we usethe method to test if the effective interactions in dissipative particledynamics (DPD) can be adjusted to produce a force covariance consistent with aprojection of a microscopic Lennard-Jones simulation. The results indicate thatthe DPD ansatz may not be consistent with the underlying microscopic dynamics.We discuss how this result relates to theoretical studies reported in theliterature.


Instruction: what is the prompt that generates the input?

Input: In the work, the new method for the design of the wavelength divisionmultiplexer on the basis of 2D photonic crystal integrated circuit for theultra-short pulses channel separation is proposed and investigated. The methodis based on the analysis of full photonic bandgap maps that allows defining theultra-short pulse demultiplexer parameters selection. For the methodapprobation, there was synthesized the device in which the wideband filters areused for the channel separation. As it was expected, the device effectivelyseparates 50 fs pulse channels with 1.31 and 1.55 microns wavelengths. Theobtained spectral characteristics and pulse pattern responses validate theefficiency of the proposed method and the applicability of such devices to theintegrated photonic information processing circuits.


Instruction: what is the prompt that generates the input?

Input: We study the evolution of a neutral $K$ meson prepared as an incoherent equalmixture of $K^0$ and $\bar{K^0}$. Denoting the density matrix by $\rho(t) ={1/2} N(t) [\1 + \vec{\zeta}(t) \cdot \vec{\sigma} ] $, the norm of the state$N(t)$ is found to decrease monotonically from one to zero, while the magnitudeof the Stokes vector $|\vec{\zeta}(t)|$ increases monotonically from zero toone. This property qualifies these observables as arrows of time. Requiringmonotonic behaviour of $N(t)$ for arbitrary values of $\gamma_L, \gamma_S$ and$\Delta m$ yields a bound on the CP-violating overlap $\delta =\braket{K_L}{K_S}$, which is similar to, but weaker than, the known unitaritybound. A similar requirement on $|\vec{\zeta}(t)|$ yields a new bound,$\delta^2 < {1/2} (\frac{\Delta \gamma}{\Delta m}) \sinh (\frac{3\pi}{4}\frac{\Delta \gamma}{\Delta m})$ which is particularly effective in limitingthe CP-violating overlap in the $B^0$-$\bar{B^0}$ system. We obtain the Stokesparameter $\zeta_3(t)$ which shows how the average strangeness of the beamevolves from zero to $\delta$. The evolution of the Stokes vector from$|\vec{\zeta}| = 0$ to $|\vec{\zeta}| = 1$ has a resemblance to an orderparameter of a system undergoing spontaneous symmetry breaking.


Instruction: what is the prompt that generates the input?

Input: We consider maximum solution $g(t)$, $t\in [0, +\infty)$, to the normalizedRicci flow. Among other things, we prove that, if $(M, \omega) $ is a smoothcompact symplectic 4-manifold such that $b_2^+(M)>1$ and let$g(t),t\in[0,\infty)$, be a solution to (1.3) on $M$ whose Ricci curvaturesatisfies that $|\text{Ric}(g(t))|\leq 3$ and additionally $\chi(M)=3 \tau(M)>0$, then there exists an $m\in \mathbb{N}$, and a sequence of points$\{x_{j,k}\in M\}$, $j=1, ..., m$, satisfying that, by passing to asubsequence, $$(M, g(t_{k}+t), x_{1,k},..., x_{m,k})\stackrel{d_{GH}}\longrightarrow (\coprod_{j=1}^m N_j, g_{\infty},x_{1,\infty}, ...,, x_{m,\infty}),$$ $t\in [0, \infty)$, in the $m$-pointedGromov-Hausdorff sense for any sequence $t_{k}\longrightarrow \infty$, where$(N_{j}, g_{\infty})$, $j=1,..., m$, are complete complex hyperbolic orbifoldsof complex dimension 2 with at most finitely many isolated orbifold points.Moreover, the convergence is $C^{\infty}$ in the non-singular part of$\coprod_1^m N_{j}$ and$\text{Vol}_{g_{0}}(M)=\sum_{j=1}^{m}\text{Vol}_{g_{\infty}}(N_{j})$, where$\chi(M)$ (resp. $\tau(M)$) is the Euler characteristic (resp. signature) of$M$.


Instruction: what is the prompt that generates the input?

Input: We study five-dimensional black holes obtained by compactifying M theory onCalabi-Yau threefolds. Recent progress in solving topological string theory oncompact, one-parameter models allows us to test numerically various conjecturesabout these black holes. We give convincing evidence that a microscopicdescription based on Gopakumar-Vafa invariants accounts correctly for theirmacroscopic entropy, and we check that highly nontrivial cancellations -whichseem necessary to resolve the so-called entropy enigma in the OSV conjecture-do in fact occur. We also study analytically small 5d black holes obtained bywrapping M2 branes in the fiber of K3 fibrations. By using heterotic/type IIduality we obtain exact formulae for the microscopic degeneracies in variousgeometries, and we compute their asymptotic expansion for large charges.


Instruction: what is the prompt that generates the input?

Input: We study the effects produced by D-brane instantons on the holomorphicquantities of a D-brane gauge theory at an orbifold singularity. These effectsare not limited to reproducing the well known contributions of the gauge theoryinstantons but also generate extra terms in the superpotential or theprepotential. On these brane instantons there are some neutral fermioniczero-modes in addition to the ones expected from broken supertranslations. Theyare crucial in correctly reproducing effects which are dual to gauge theoryinstantons, but they may make some other interesting contributions vanish. Weanalyze how orientifold projections can remove these zero-modes and thus allowfor new superpotential terms. These terms contribute to the dynamics of theeffective gauge theory, for instance in the stabilization of runawaydirections.


Instruction: what is the prompt that generates the input?

Input: We present observations of pure rotational molecular hydrogen emission fromthe Herbig Ae star, AB Aurigae. Our observations were made using the TexasEchelon Cross Echelle Spectrograph (TEXES) at the NASA Infrared TelescopeFacility and the Gemini North Observatory. We searched for H2 emission in theS(1), S(2), and S(4) lines at high spectral resolution and detected all three.By fitting a simple model for the emission in the three transitions, we deriveT = 670 +/- 40 K and M = 0.52 +/- 0.15 earth masses for the emitting gas. Basedon the 8.5 km/s FWHM of the S(2) line, assuming the emission comes from thecircumstellar disk, and with an inclination estimate of the AB Aur system takenfrom the literature, we place the location for the emission near 18 AU.Comparison of our derived temperature to a disk structure model suggests thatUV and X-ray heating are important in heating the disk atmosphere.


Instruction: what is the prompt that generates the input?

Input: BACKGROUND: An important question is whether evolution favors properties suchas mutational robustness or evolvability that do not directly benefit anyindividual, but can influence the course of future evolution. Functionallysimilar proteins can differ substantially in their robustness to mutations andcapacity to evolve new functions, but it has remained unclear whether any ofthese differences might be due to evolutionary selection for these properties.  RESULTS: Here we use laboratory experiments to demonstrate that evolutionfavors protein mutational robustness if the evolving population is sufficientlylarge. We neutrally evolve cytochrome P450 proteins under identical selectionpressures and mutation rates in populations of different sizes, and show thatproteins from the larger and thus more polymorphic population tend towardshigher mutational robustness. Proteins from the larger population also evolvegreater stability, a biophysical property that is known to enhance bothmutational robustness and evolvability. The excess mutational robustness andstability is well described by existing mathematical theories, and can bequantitatively related to the way that the proteins occupy their neutralnetwork.  CONCLUSIONS: Our work is the first experimental demonstration of the generaltendency of evolution to favor mutational robustness and protein stability inhighly polymorphic populations. We suggest that this phenomenon may contributeto the mutational robustness and evolvability of viruses and bacteria thatexist in large populations.


Instruction: what is the prompt that generates the input?

Input: We report a computational first-principles study of positron trapping atvacancy defects in metals and semiconductors. The main emphasis is on theenergetics of the trapping process including the interplay between the positronstate and the defect's ionic structure and on the ensuing annihilationcharacteristics of the trapped state. For vacancies in covalent semiconductorsthe ion relaxation is a crucial part of the positron trapping process enablingthe localization of the positron state. However, positron trapping does notstrongly affect the characteristic features of the electronic structure, e.g.,the ionization levels change only moderately. Also in the case of metalvacancies the positron-induced ion relaxation has a noticeable effect on thecalculated positron lifetime and momentum distribution of annihilatingelectron-positron pairs.


Instruction: what is the prompt that generates the input?

Input: Berry phases and the quantum-information theoretic notion of fidelity havebeen recently used to analyze quantum phase transitions from a geometricalperspective. In this paper we unify these two approaches showing that theunderlying mechanism is the critical singular behavior of a complex tensor overthe Hamiltonian parameter space. This is achieved by performing a scalinganalysis of this quantum geometric tensor in the vicinity of the criticalpoints. In this way most of the previous results are understood on generalgrounds and new ones are found. We show that criticality is not a sufficientcondition to ensure superextensive divergence of the geometric tensor, andstate the conditions under which this is possible. The validity of thisanalysis is further checked by exact diagonalization of the spin-1/2 XXZHeisenberg chain.


Instruction: what is the prompt that generates the input?

Input: The mass loss properties of carbon AGB stars are not very well constrained atpresent. A variety of empirical or theoretical formulae with differentparameterisations are available in the literature and the agreement betweenthem is anything but good. These simple mass loss prescriptions are nonthelessused in many models of stellar evolution without much consideration of theirapplicability in various cases. We present here an on-going project aiming at abetter description of the mass loss, that could be used to improve stellarevolution models -- especially the evolution during the TP-AGB phase. As afirst step, we have considered the mass loss evolution during a He-shell flash.Using stellar parameters sampled from a stellar evolutionary track, we havecomputed the time evolution of the atmospheric layers and wind accelerationregion during a flash event with detailed frequency-dependentradiation-hydrodynamical models including dust formation. Based on theseresults, we have also simulated the subsequent long-term dynamical evolution ofthe circumstellar envelope (CSE), including the formation of a detached shell.We find that existing simple mass loss prescriptions imply different mass lossevolutions compared with our model. The second step of the project deals withthe dependence of mass loss on the basic stellar parameters. At the moment weare computing a large grid of wind models for C-rich AGB stars. Preliminaryresults show that simple parameterisations are difficult to obtain in certainregions of the parameter space considered, due to strong non-linearities in thewind mechanism.


Instruction: what is the prompt that generates the input?

Input: A number of recently discovered protein structures incorporate a ratherunexpected structural feature: a knot in the polypeptide backbone. These knotsare extremely rare, but their occurrence is likely connected to proteinfunction in as yet unexplored fashion. Our analysis of the complete ProteinData Bank reveals several new knots which, along with previously discoveredones, can shed light on such connections. In particular, we identify the mostcomplex knot discovered to date in human ubiquitin hydrolase, and suggest thatits entangled topology protects it against unfolding and degradation by theproteasome. Knots in proteins are typically preserved across species andsometimes even across kingdoms. However, we also identify a knot which onlyappears in some transcarbamylases while being absent in homologous proteins ofsimilar structure. The emergence of the knot is accompanied by a shift in theenzymatic function of the protein. We suggest that the simple insertion of ashort DNA fragment into the gene may suffice to turn an unknotted into aknotted structure in this protein.


Instruction: what is the prompt that generates the input?

Input: Electron-electron interactions play a major role in determining thelow-temperature rate of phase loss of electrons in mesoscopic systems. Thestudy of the dephasing rate is expected to contribute to the understanding ofthe many-body nature of such systems. Closed quantum dots are of specialinterest in this respect, due to theoretical predictions suggesting a possibletransition temperature below which the dephasing rate vanishes. This predictionhas attracted much attention, since closed quantum dots are prime candidatesfor storage units in quantum computers, and thus their phase coherenceproperties are of great importance. However, an effective method for measuringthe dephasing rate within a closed quantum dot is still lacking. Here we studytwo-level systems and show that the Fano factor has a sharp peak as a functionof the chemical potential, the location of which can be simply related to thedephasing rate. We thus suggest to use the properties of the Fano factor peakin the super-Poissonian regime as a probe for the dephasing rate.


Instruction: what is the prompt that generates the input?

Input: In braneworld cosmology the expanding Universe is realized as a brane movingthrough a warped higher-dimensional spacetime. Like a moving mirror causes thecreation of photons out of vacuum fluctuations, a moving brane leads tograviton production. We show that, very generically, Kaluza-Klein (KK)particles scale like stiff matter with the expansion of the Universe and cantherefore not represent the dark matter in a warped braneworld. We presentresults for the production of massless and KK gravitons for bouncing branes infive-dimensional anti de Sitter space. We find that for a realistic bounce theback reaction from the generated gravitons will be most likely relevant. Thisletter summarizes the main results and conclusions from numerical simulationswhich are presented in detail in a long paper [M.Ruser and R. Durrer, Phys.Rev. D 76, 104014 (2007), arXiv:0704.0790]


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Input: Employing Big Bear Solar Observatory (BBSO) deep magnetograms and H${\alpha}$images in a quiet region and a coronal hole, observed on September 14 and 16,2004, respectively, we have explored the magnetic flux emergence, disappearanceand distribution in the two regions. The following results are obtained: (1)The evolution of magnetic flux in the quiet region is much faster than that inthe coronal hole, as the flux appeared in the form of ephemeral regions in thequiet region is 4.3 times as large as that in the coronal hole, and the fluxdisappeared in the form of flux cancellation, 2.9 times as fast as in thecoronal hole. (2) More magnetic elements with opposite polarities in the quietregion are connected by arch filaments, estimating from magnetograms andH${\alpha}$ images. (3) We measured the magnetic flux of about 1000 magneticelements in each observing region. The flux distribution of network andintranetwork (IN) elements is similar in both polarities in the quiet region.For network fields in the coronal hole, the number of negative elements is muchmore than that of positive elements. However for the IN fields, the number ofpositive elements is much more than that of negative elements. (4) In thecoronal hole, the fraction of negative flux change obviously with differentthreshold flux density. 73% of the magnetic fields with flux density largerthan 2 Gauss is negative polarity, and 95% of the magnetic fields is negative,if we only measure the fields with their flux density larger than 20 Gauss. Ourresults display that in a coronal hole, stronger fields is occupied by onepredominant polarity; however the majority of weaker fields, occupied by theother polarity.


Instruction: what is the prompt that generates the input?

Input: We investigate the detailed dynamics of multidimensional Hamiltonian systemsby studying the evolution of volume elements formed by unit deviation vectorsabout their orbits. The behavior of these volumes is strongly influenced by theregular or chaotic nature of the motion, the number of deviation vectors, theirlinear (in)dependence and the spectrum of Lyapunov exponents. The differenttime evolution of these volumes can be used to identify rapidly and efficientlythe nature of the dynamics, leading to the introduction of quantities thatclearly distinguish between chaotic behavior and quasiperiodic motion on$N$-dimensional tori. More specifically we introduce the Generalized AlignmentIndex of order $k$ (GALI$_k$) as the volume of a generalized parallelepiped,whose edges are $k$ initially linearly independent unit deviation vectors fromthe studied orbit whose magnitude is normalized to unity at every time step.The GALI$_k$ is a generalization of the Smaller Alignment Index (SALI)(GALI$_2$ $\propto$ SALI). However, GALI$_k$ provides significantly moredetailed information on the local dynamics, allows for a faster and clearerdistinction between order and chaos than SALI and works even in cases where theSALI method is inconclusive.


Instruction: what is the prompt that generates the input?

Input: The sub-millimetre wavelength regime is perhaps the most poorly explored overlarge areas of the sky, despite the considerable effort that has been expendedin making deep maps over small regions. As a consequence the properties of thesub-millimetre sky as a whole, and of rare bright objects in particular,remains largely unknown. Here we describe a forthcoming survey (the SCUBA-2``All-Sky'' Survey, or SASSy) designed to address this issue by making alarge-area map of approximately one-fifth of the sky visible from the JCMT(4800 square degrees) down to a 1 sigma noise level of 30 mJy/beam. This mapforms the pilot for a much larger survey, which will potentially map theremaining sky visible from the JCMT, with the region also visible to ALMA as apriority. SASSy has been awarded 500 hours for the 4800 square degree pilotphase and will commence after the commissioning of SCUBA-2, expected in early2008.


Instruction: what is the prompt that generates the input?

Input: Phylogenetic mixtures model the inhomogeneous molecular evolution commonlyobserved in data. The performance of phylogenetic reconstruction methods wherethe underlying data is generated by a mixture model has stimulated considerablerecent debate. Much of the controversy stems from simulations of mixture modeldata on a given tree topology for which reconstruction algorithms output a treeof a different topology; these findings were held up to show the shortcomingsof particular tree reconstruction methods. In so doing, the underlyingassumption was that mixture model data on one topology can be distinguishedfrom data evolved on an unmixed tree of another topology given enough data andthe ``correct'' method. Here we show that this assumption can be false. Forbiologists our results imply that, for example, the combined data from twogenes whose phylogenetic trees differ only in terms of branch lengths canperfectly fit a tree of a different topology.


Instruction: what is the prompt that generates the input?

Input: Computational asymmetry, i.e., the discrepancy between the complexity oftransformations and the complexity of their inverses, is at the core of one-waytransformations. We introduce a computational asymmetry function that measuresthe amount of one-wayness of permutations. We also introduce the word-lengthasymmetry function for groups, which is an algebraic analogue of computationalasymmetry. We relate boolean circuits to words in a Thompson monoid, over afixed generating set, in such a way that circuit size is equal to word-length.Moreover, boolean circuits have a representation in terms of elements of aThompson group, in such a way that circuit size is polynomially equivalent toword-length. We show that circuits built with gates that are not constrained tohave fixed-length inputs and outputs, are at most quadratically more compactthan circuits built from traditional gates (with fixed-length inputs andoutputs). Finally, we show that the computational asymmetry function is closelyrelated to certain distortion functions: The computational asymmetry functionis polynomially equivalent to the distortion of the path length in Schreiergraphs of certain Thompson groups, compared to the path length in Cayley graphsof certain Thompson monoids. We also show that the results of Razborov andothers on monotone circuit complexity lead to exponential lower bounds oncertain distortions.


Instruction: what is the prompt that generates the input?

Input: Let $r>2$ and $\sigma\in(0,r-1)$ be integers. We require $t<2s$, where$t=2^{\sigma+1}-1$ and $s=2^{r-\sigma-1}$. Generalizing a known$\{K_4,T_{6,3}\}$-ultrahomogenous graph $G_3^1$, we find that a finite,connected, undirected, arc-transitive graph $G_r^\sigma$ exists each of whoseedges is shared by just two maximal subgraphs, namely a clique $X_0=K_{2s}$ anda $t$-partite regular-Tur\'an graph $X_1=T_{st,t}$ on $s$ vertices per part.Each copy $Y$ of $X_i$ ($i=0,1$) in $G_r^\sigma$ shares each edge with just onecopy of $X_{1-i}$ and all such copies of $X_{1-i}$ are pairwise distinct.Moreover, $G_r^\sigma$ is an edge-disjoint union of copies of $X_i$, for$i=0,1$. We prove that $G_r^\sigma$ is $\{K_{2s},T_{st,t}\}$-homogeneous if$t<2s$, and just $\{T_{st,t}\}$-homogeneous otherwise, meaning that there is anautomorphism of $G_r^\sigma$ between any two such copies of $X_i$ relating twopreselected arcs.


Instruction: what is the prompt that generates the input?

Input: Author offers and researched the new and revolutionary inflatableelectrostatic AB space towers (mast, new space elevator) up to one hundredtwenty thousands kilometers (or more) in height. The main innovation is fillingthe tower by electron gas, which can create pressure up one atmosphere, hasnegligible small weight and surprising properties.  The suggested mast has following advantages in comparison with conventionalspace elevator: 1. Electrostatic AB tower may be built from Earth surfacewithout the employment of any rockets. That decreases the cost of electrostaticmast by thousands of times. 2. One can have any height and has a big controlload capacity. 3. Electrostatic tower can have the height of a geosynchronousorbit (36,000 km) WITHOUT the additional top cable as the space elevator (up120,000 - 160,000 km) and counterweight (equalizer) of hundreds of tons. 4. Theoffered mast has less total mass than conventional space elevator. 5. Theoffered tower can have the high-speed electrostatic climbers moved byhigh-voltage electricity from Earth's surface. 6. The electrostatic mast canbend in any needed direction when we give the necessary electric voltage in therequired parts of the extended mast. 7. Control mast has stability for anyaltitude. Three projects 100 km, 36,000km (GEO), 120,000 km are computed andpresented.


Instruction: what is the prompt that generates the input?

Input: We present a model improving the two-angle model for interphase chromatin(E2A model). This model takes into account the cylindrical shape of the histoneoctamers, the H1 histones in front of the nucleosomes and the vertical distance$d$ between the in and outgoing DNA strands. Factoring these chromatin featuresin, one gets essential changes in the chromatin phase diagram: Not only theshape of the excluded-volume borderline changes but also the vertical distance$d$ has a dramatic influence on the forbidden area. Furthermore, we examinedthe influence of H1 defects on the properties of the chromatin fiber. Thus wepresent two possible strategies for chromatin compaction: The use of very densestates in the phase diagram in the gaps in the excluded volume borderline ormissing H1 histones which can lead to very compact fibers. The chromatin fibermight use both of these mechanisms to compact itself at least locally. Linedensities computed within the model coincident with the experimental values.


Instruction: what is the prompt that generates the input?

Input: We characterize the crystalline silicate content and spatial distribution ofsmall dust grains in a large sample of protoplanetary disks in theTaurus-Auriga young cluster, using Spitzer Space Telescope mid-infraredspectra. In turn we use the results to analyze the evolution of structure andcomposition of these 1-2 Myr-old disks around Solar- and later-type youngstars, and test the standard models of dust processing which result in theconversion of originally amorphous dust into minerals. We find strong evidenceof evolution of the dust crystalline mass fraction in parallel with that of thestructure of the disks, in the sense that increasing crystalline mass fractionis strongly linked to dust settling to the disk midplane. We also confirm thatthe crystalline silicates are confined to small radii, r < 10 AU. However, wesee no significant correlation of crystalline mass fraction with stellar massor luminosity, stellar accretion rate, disk mass, or disk/star mass ratio, aswould be expected in the standard models of dust processing based uponphoto-evaporation and condensation close to the central star,accretion-heating-driven annealing at r < 1 AU, or spiral-shock heating at r <10 AU, with or without effective radial mixing mechanisms. Either anothergrain-crystallizing mechanism dominates over these, or another process must beat work within the disks to erase the correlations they produce. We propose oneof each sort that seem to be worth further investigation, namely X-ray heatingand annealing of dust grains, and modulation of disk structure bygiant-planetary formation and migration.


Instruction: what is the prompt that generates the input?

Input: I consider the question of the interaction between a QCD string and the spinof a quark or an antiquark on whose worldline the string terminates. Theproblem is analysed from the point of view of a string representation for theexpectation value of a Wilson loop for a spin-half particle. A stringrepresentation of the super Wilson loop is obtained starting from an effectivestring representation of a Wilson Loop. The action obtained in this manner isinvariant under a worldline supersymmetry and has a boundary term whichcontains the spin-string interaction. For rectangular loops the spin-stringinteraction vanishes and there is no spin-spin term in the resulting heavyquark potential. On the other hand if an allowance is made for the finiteintrinsic thickness of the flux-tube, by assuming that the spin-stringinteraction takes place not just at the boundary of the string world-sheet butextends to a distance of the order of the intrinsic thickness of the flux tube,then we do obtain a spin-spin interaction which falls as the fifth power of thedistance. Such a term was previously suggested by Kogut and Parisi in thecontext of a flux-tube model of confinement.


Instruction: what is the prompt that generates the input?

Input: Production of $D_{sJ}$(2317) mesons in relativistic heavy ion collisions atRHIC is studied. Using the quark coalescence model, we first determine theinitial number of $D_{sJ}$(2317) mesons produced during hadronization ofcreated quark-gluon plasma. The predicted $D_{sJ}$(2317) abundance dependssensitively on the quark structure of the $D_{sJ}$(2317) meson. Anorder-of-magnitude larger yield is obtained for a conventional two-quark thanfor an exotic four-quark $D_{sJ}$(2317) meson. To include the hadronic effecton the $D_{sJ}$(2317) meson yield, we have evaluated the absorption crosssections of the $D_{sJ}$(2317) meson by pion, rho, anti-kaon, and vectoranti-kaon in a phenomenological hadronic model. Taking into consideration theabsorption and production of $D_{sJ}$(2317) mesons during the hadronic stage ofheavy ion collisions via a kinetic model, we find that the final yield of$D_{sJ}$(2317) mesons remains sensitive to its initial number produced from thequark-gluon plasma, providing thus the possibility of studying the quarkstructure of the $D_{sJ}$(2317) meson and its production mechanism inrelativistic heavy ion collisions.


Instruction: what is the prompt that generates the input?

Input: We investigate the growth of half metallic phase in a ferromagnetic materialusing state-of-the-art full potential linearized augmented plane wave method.To address the issue, we have substituted Ti at the Ru-sites in SrRuO3, whereSrRuO3 is a ferromagnetic material. Calculated results establish Ti4+ valencestates (similar to SrTiO3), which was predicted experimentally. Thus, Tisubstitution dilutes the Ru-O-Ru connectivity, which is manifested in thecalculated results in the form of significant band narrowing leading to finitegap between t2g and eg bands. At 75% substitution, a large gap (> 2 eV) appearsat the Fermi level, e_F in the up spin density of states, while the down spinstates contributes at e_F characterizing the system a half-metallicferromagnet. The t2g - eg gap can be tailored judiciously by tuning Ticoncentrations to minimize thermal effects, which is often the major bottleneckto achieve high spin polarization at elevated temperatures in other materials.This study, thus, provides a novel but simple way to fabricate half-metallicityin ferromagnetic materials, which are potential candidates for spin-basedtechnology.


Instruction: what is the prompt that generates the input?

Input: The physical interpretation of scattering line polarization offers a noveldiagnostic window for exploring the thermal and magnetic structure of the quietregions of the solar atmosphere. Here we evaluate the impact of isotropiccollisions with neutral hydrogen atoms on the scattering polarization signalsof the 13 lines of multiplet 42 of Ti I and on those of the K line and of theIR triplet of Ca II, with emphasis on the collisional transfer rates betweennearby J-levels. To this end, we calculate the linear polarization produced byscattering processes considering realistic multilevel models and solving thestatistical equilibrium equations for the multipolar components of the atomicdensity matrix. We confirm that the lower levels of the 13 lines of multiplet42 of Ti I are completely depolarized by elastic collisions. We find thatupper-level collisional depolarization turns out to have an unnoticeable impacton the emergent linear polarization amplitudes, except for the ${\lambda 4536$line for which it is possible to notice a rather small depolarization caused bythe collisional transfer rates. Concerning the Ca II lines, we show that thecollisional rates play no role on the polarization of the upper level of the Kline, while they have a rather small depolarizing effect on the atomicpolarization of the metastable lower levels of the Ca II IR triplet.


Instruction: what is the prompt that generates the input?

Input: We present results of a 20 ksec X-ray observation of the Wolf-Rayet (WR)binary system WR 147 obtained with XMM-Newton. Previous studies have shown thatthis system consists of a nitrogen-type WN8 star plus an OB companion whosewinds are interacting to produce a colliding wind shock. X-ray spectra from thepn and MOS detectors confirm the high extinction reported from IR studies andreveal hot plasma including the first detection of the Fe K-alpha line complexat 6.67 keV. Spectral fits with a constant-temperature plane-parallel shockmodel give a shock temperature kT(shock) = 2.7 keV [T(shock) ~ 31 MK], close tobut slightly hotter than the maximum temperature predicted for a colliding windshock. Optically thin plasma models suggest even higher temperatures, which arenot yet ruled out. The X-ray spectra are harder than can be accounted for using2D numerical colliding wind shock models based on nominal mass-loss parameters.Possible explanations include: (i) underestimates of the terminal wind speedsor wind abundances, (ii) overly simplistic colliding wind models, or (iii) thepresence of other X-ray emission mechanisms besides colliding wind shocks.Further improvement of the numerical models to include potentially importantphysics such as non-equilibrium ionization will be needed to rigorously testthe colliding wind interpretation.


Instruction: what is the prompt that generates the input?

Input: We investigate non-perturbative features of a three-dimensional Abelian Higgsmodel with singly- and doubly-charged scalar fields coupled to a single compactAbelian gauge field. The model is pretending to describe various planar systemsof strongly correlated electrons such as high-Tc superconductivity in theoverdoped regime and exotic materials possessing excitations withfractionalized quantum numbers. The complicated phase structure of the model isstudied thoroughly using numerical tools and analytical arguments. In thethree-dimensional space of coupling parameters we identify the Fermi liquid,the spin gap, the superconductor and the strange metallic phases. The behaviorof three kinds of topological defects -- holon and spinon vortices andmonopoles - is explored in various phases. We also observe a new effect, thestrong enhancement of the phase transition strength reflected in a lower orderof the transition: at sufficiently strong gauge coupling the two second orderphase transitions -- corresponding to spinon-pair and holon condensation lines- join partially in the phase diagram and become a first order phase transitionin that region. The last observation may have an analogue in QuantumChromodynamics at non-zero temperature and finite baryon density. We argue thatat sufficiently large baryon density the finite-temperature transition betweenthe (3-flavor paired) color superconducting phase and the quark-gluon plasmaphases should be much stronger compared with the transition between 2-flavorpaired and 3-flavor paired superconducting phases.


Instruction: what is the prompt that generates the input?

Input: We present the results of a uniform analysis of the soft X-ray spectra offifteen type I AGN observed with the high resolution X-ray gratings on board\emph{Chandra}. We found that ten of the fifteen AGN exhibit signatures of anintrinsic ionized absorber. The absorbers are photoionized and outflowing, withvelocities in the range $\sim 10^{1}-10^{3}$ km $\rm{s}^{-1}$. The columndensity of the warm absorbing gas is $\sim 10^{20-23} \rm{cm}^{-2}$. Nine ofthe ten AGN exhibiting warm absorption are best--fit by multiple ionizationcomponents and three of the ten AGN \emph{require} multiple kinematiccomponents. The warm absorbing gas in our AGN sample has a wide range ofionization parameter, spanning roughly four orders of magnitude ($\xi \sim10^{0-4}$ ergs cm $\rm{s}^{-1}$) in total, and often spanning three orders ofmagnitude in the same gas. Warm absorber components with ionization parameter$\xi<10$ generate an unresolved transition array due to Fe in seven of the tenAGN exhibiting warm absorption. These low ionization state absorbers may alsocarry away the largest mass outflows from the AGN. The mass outflow ratedepends critically on the volume filling factor of the gas, which cannot yet bedirectly measured. However, upper limits on the mass outflow ratesfor fillingfactors of unity can be much greater than the expected accretion rate onto thecentral supermassive black hole and filling factors as small as 1% can giveoutflow rates comparable to the accretion rate. There appears to be a gap inthe outflow velocities in our sample between $\sim 300-500$ km $\rm{s}^{-1}$,the origin of which is not clear. The outflow components with velocities belowthis gap tend to be associated with lower column densities than those withvelocities above the gap.


Instruction: what is the prompt that generates the input?

Input: We introduce a new spinfoam vertex to be used in models of 4d quantum gravitybased on SU(2) and SO(4) BF theory plus constraints. It can be seen as theconventional vertex of SU(2) BF theory, the 15j symbol, in a particular basisconstructed using SU(2) coherent states. This basis makes the geometricinterpretation of the variables transparent: they are the vectors normal to thetriangles within each tetrahedron. We study the condition under which thesestates can be considered semiclassical, and we show that the semiclassical onesdominate the evaluation of quantum correlations. Finally, we describe how theconstraints reducing BF to gravity can be directly written in terms of the newvariables, and how the semiclassicality of the states might improveunderstanding the correct way to implement the constraints.


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Input: A model for charge transfer mechanism in YBa2Cu3O6+x high-Tc cuprate based oncritical chain length concept is proposed to account for 60K and 90K plateausin Tc(x) dependence. It has been shown, when the statistics of CuO chainformation was described in terms of two dimensional asymmetric next-to-nearestneighbor Ising (ASYNNNI) model, that at any constant temperature below the topof OII phase there exists a uniquely defined value of critical chain lengthlcr(T) that yields a constant doping p(x)=const over the regime of OII phase(related to 60K plateau of Tc(x)), while 90K plateau coincides with themonotonously increasing p(x) over optimal doping level p=0.16 in the regime ofOI phase. Short length chains (l<lcr(T)), together with the first lcr(T)-2holes in longer chains (l>lcr(T)), are taken as not capable of attractingelectrons from CuO2 planes.. It is shown that only a part (41%) of theremaining l-lcr(T)+1 holes in the long chains can capture electrons. Theresults obtained indicate that the ASYNNNI model and two-plateaus-like behaviorof Tc(x) in YBa2Cu3O6+x are closely connected.


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Input: Gravitational lenses on galaxy scales are plausibly modelled as havingellipsoidal symmetry and a universal dark matter density profile, with a Sersicprofile to describe the distribution of baryonic matter. Predicting all lensingeffects requires knowledge of the total lens potential: in this work we giveanalytic forms for that of the above hybrid model. Emphasising that complexlens potentials can be constructed from simpler components in linearcombination, we provide a recipe for attaining elliptical symmetry in eitherprojected mass or lens potential. We also provide analytic formulae for thelens potentials of Sersic profiles for integer and half-integer index. We thenpresent formulae describing the gravitational lensing effects due tosmoothly-truncated universal density profiles in cold dark matter model. Forour isolated haloes the density profile falls off as radius to the minus fifthor seventh power beyond the tidal radius, functional forms that allow allorders of lens potential derivatives to be calculated analytically, whileensuring a non-divergent total mass. We show how the observables predicted bythis profile differ from that of the original infinite-mass NFW profile.Expressions for the gravitational flexion are highlighted. We show howdecreasing the tidal radius allows stripped haloes to be modelled, providing aframework for a fuller investigation of dark matter substructure in galaxiesand clusters. Finally we remark on the need for finite mass halo profiles whendoing cosmological ray-tracing simulations, and the need for readily-calculablehigher order derivatives of the lens potential when studying catastrophes instrong lenses.


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Input: The presence of dust at high redshift requires efficient condensation ofgrains in SN ejecta, in accordance with current theoretical models. Yet,observations of the few well studied SNe and SN remnants imply condensationefficiencies which are about two orders of magnitude smaller. Motivated by thistension, we have (i) revisited the model of Todini & Ferrara (2001) for dustformation in the ejecta of core collapse SNe and (ii) followed, for the firsttime, the evolution of newly condensed grains from the time of formation totheir survival - through the passage of the reverse shock - in the SN remnant.We find that 0.1 - 0.6 M_sun of dust form in the ejecta of 12 - 40 M_sunstellar progenitors. Depending on the density of the surrounding ISM, between2-20% of the initial dust mass survives the passage of the reverse shock, ontime-scales of about 4-8 x 10^4 yr from the stellar explosion. Sputtering bythe hot gas induces a shift of the dust size distribution towards smallergrains. The resulting dust extinction curve shows a good agreement with thatderived by observations of a reddened QSO at z =6.2. Stochastic heating ofsmall grains leads to a wide distribution of dust temperatures. This supportsthe idea that large amounts (~ 0.1 M_sun) of cold dust (T ~ 40K) can be presentin SN remnants, without being in conflict with the observed IR emission.


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Input: We report the detection of five Jovian mass planets orbiting high metallicitystars. Four of these stars were first observed as part of the N2K program andexhibited low RMS velocity scatter after three consecutive observations.However, follow-up observations over the last three years now reveal thepresence of longer period planets with orbital periods ranging from 21 days toa few years. HD 11506 is a G0V star with a planet of \msini = 4.74 \mjup in a3.85 year orbit. HD 17156 is a G0V star with a 3.12 \mjup planet in a 21.2 dayorbit. The eccentricity of this orbit is 0.67, one of the highest known for aplanet with a relatively short period. The orbital period for this planetplaces it in a region of parameter space where relatively few planets have beendetected. HD 125612 is a G3V star with a planet of \msini = 3.5 \mjup in a 1.4year orbit. HD 170469 is a G5IV star with a planet of \msini = 0.67 \mjup in a3.13 year orbit. HD 231701 is an F8V star with planet of 1.08 \mjup in a 142day orbit. All of these stars have supersolar metallicity. Three of the fivestars were observed photometrically but showed no evidence of brightnessvariability. A transit search conducted for HD 17156 was negative but coveredonly 25% of the search space and so is not conclusive.


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Input: N-body simulations give us a rough idea of how the shape of a simulatedobject appears in three-dimensional space. From an observational point of viewthis may give us a misleading picture. The faint stars may be the most commonstars in the system but the morphological information obtained by observationsof an object may be dominated by the color properties of the bright stars. Dueto dynamical effects, such as energy equipartition, different masses of starsmay populate different regions in the object. Since stars are evolving in massthe stellar evolution may also influence the dynamics of the system. Hence, ifone is interested in simulating what the morphology will look like through atelescope, one needs to simulate in addition evolving stars and weight them bytheir luminosity. Therefore we need to combine simulations of the dynamicalevolution and a stellar population synthesis at the same time. For thedynamical evolution part we use a parallel version of a direct N-body code,NBODY6++. This code also includes stellar evolution. We link the parametersfrom this stellar evolution routine to the BaSeL 2.0 stellar library. Forisolated clusters we found results assimilable to standard stellar populationsynthesis codes such as the PEGASE code. For clusters in a tidal field we foundthat the integrated colors become relatively bluer due to energy equipartitioneffects. In the time shortly before dissolution of the cluster the stellar M/Lratio becomes lower compared to isolated clusters. We compared the results ofour simulations to integrated spectra of galactic globular clusters. For thecluster NGC 1851 we found good agreement between simulation and observation.For extragalactic clusters in M81 and M31 we looked at medium band spectralenergy distributions and found for some clusters also a good agreement.


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Input: We show that the conditions which originate the spin and pseudospinsymmetries in the Dirac equation are the same that produce equivalent energyspectra of relativistic spin-1/2 and spin-0 particles in the presence of vectorand scalar potentials. The conclusions do not depend on the particular shapesof the potentials and can be important in different fields of physics. Whenboth scalar and vector potentials are spherical, these conditions forisospectrality imply that the spin-orbit and Darwin terms of either the uppercomponent or the lower component of the Dirac spinor vanish, making itequivalent, as far as energy is concerned, to a spin-0 state. In this case,besides energy, a scalar particle will also have the same orbital angularmomentum as the (conserved) orbital angular momentum of either the upper orlower component of the corresponding spin-1/2 particle. We point out a fewpossible applications of this result.


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Input: We study the application of AdS/CFT duality to longitudinal boost invariantBjorken expansion of QCD matter produced in ultrarelativistic heavy ioncollisions. As the exact (1+4)-dimensional bulk solutions for the(1+3)-dimensional boundary theory are not known, we investigate in detail the(1+1)-dimensional boundary theory, where the bulk is AdS_3 gravity. We find anexact bulk solution, show that this solution describes part of the spinlessBanados-Teitelboim-Zanelli (BTZ) black hole with the angular dimensionunwrapped, and use the thermodynamics of the BTZ hole to recover thetime-dependent temperature and entropy density on the boundary. Afterseparating from the holographic energy-momentum tensor a vacuum contribution,given by the extremal black hole limit in the bulk, we find that the boundaryfluid is an ideal gas in local thermal equilibrium. Including angular momentumin the bulk gives a boundary flow that is boost invariant but has a nonzerolongitudinal velocity with respect to the Bjorken expansion.


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Input: Star patterns, reminiscent of a wide range of diffusively controlled growthforms from snowflakes to Saffman-Taylor fingers, are ubiquitous features of icecovered lakes. Despite the commonality and beauty of these ``lake stars'' theunderlying physical processes that produce them have not been explained in acoherent theoretical framework. Here we describe a simple mathematical modelthat captures the principal features of lake-star formation; radial fingers of(relatively warm) water-rich regions grow from a central source and evolvethrough a competition between thermal and porous media flow effects in asaturated snow layer covering the lake. The number of star arms emerges from astability analysis of this competition and the qualitative features of thismeter-scale natural phenomena are captured in laboratory experiments.


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Input: We present a detailed analysis of the Galaxy Stellar Mass Function ofgalaxies up to z=2.5 as obtained from the VVDS. We estimate the stellar massfrom broad-band photometry using 2 different assumptions on the galaxy starformation history and show that the addition of secondary bursts to acontinuous star formation history produces systematically higher (up to 40%)stellar masses. At low redshift (z=0.2) we find a substantial population oflow-mass galaxies (<10^9 Msun) composed by faint blue galaxies (M_I-M_K=0.3).In general the stellar mass function evolves slowly up to z=0.9 and moresignificantly above this redshift. Conversely, a massive tail is present up toz=2.5 and have extremely red colours (M_I-M_K=0.7-0.8). We find a decline withredshift of the overall number density of galaxies for all masses (59+-5% forM>10^8 Msun at z=1), and a mild mass-dependent average evolution(`mass-downsizing'). In particular our data are consistent with mild/negligible(<30%) evolution up to z=0.7 for massive galaxies (>6x10^10 Msun). For lessmassive systems the no-evolution scenario is excluded. A large fraction (>=50%)of massive galaxies have been already assembled and converted most of their gasinto stars at z=1, ruling out the `dry mergers' as the major mechanism of theirassembly history below z=1. This fraction decreases to 33% at z=2. Low-masssystems have decreased continuously in number and mass density (by a factor upto 4) from the present age to z=2, consistently with a prolonged mass assemblyalso at z<1.


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Input: We present a comprehensive mass reconstruction of the rich galaxy cluster Cl0024+17 at z~0.4 from ACS data, unifying both strong- and weak-lensingconstraints. The weak-lensing signal from a dense distribution of backgroundgalaxies (~120 per square arcmin) across the cluster enables the derivation ofa high-resolution parameter-free mass map. The strongly-lensed objects tightlyconstrain the mass structure of the cluster inner region on an absolute scale,breaking the mass-sheet degeneracy. The mass reconstruction of Cl 0024+17obtained in such a way is remarkable. It reveals a ringlike dark mattersubstructure at r~75" surrounding a soft, dense core at r~50". We interpretthis peculiar sub-structure as the result of a high-speed line-of-sightcollision of two massive clusters 1-2 Gyr ago. Such an event is also indicatedby the cluster velocity distribution. Our numerical simulation with purelycollisionless particles demonstrates that such density ripples can arise byradially expanding, decelerating particles that originally comprised thepre-collision cores. Cl 0024+17 can be likened to the bullet cluster 1E0657-56,but viewed $along$ the collision axis at a much later epoch. In addition, weshow that the long-standing mass discrepancy for Cl 0024+17 between X-ray andlensing can be resolved by treating the cluster X-ray emission as coming from asuperposition of two X-ray systems. The cluster's unusual X-ray surfacebrightness profile that requires a two isothermal sphere description supportsthis hypothesis.


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Input: We combined sensitive near-infrared data obtained with ground-based imagerson the ESO NTT and VLT telescopes with space mid-infrared data acquired withthe IRAC imager on the Spitzer Space Telescope to calculate the extinction lawA_\lambda/A_K as a function of \lambda between 1.25 and 7.76 micron to anunprecedented depth in Barnard 59, a star forming, dense core located in thePipe Nebula. The ratios A_\lambda/A_K were calculated from the slopes of thedistributions of sources in color-color diagrams \lambda-K vs. H-K. Thedistributions in the color-color diagrams are fit well with single slopes toextinction levels of A_K ~ 7 (A_V ~ 59 mag). Consequently, there appears to beno significant variation of the extinction law with depth through the B59 lineof sight. However, when slopes are translated into the relative extinctioncoefficients A_\lambda/A_K, we find an extinction law which departs from thesimple extrapolation of the near-infrared power law extinction curve, andagrees more closely with a dust extinction model for a cloud with a total toselective absorption R_V=5.5 and a grain size distribution favoring largergrains than those in the diffuse ISM. Thus, the difference we observe could bepossibly due to the effect of grain growth in denser regions. Finally, theslopes in our diagrams are somewhat less steep than those from the study ofIndebetouw et al. (2005) for clouds with lower column densities, and thisindicates that the extinction law between 3 and 8 micron might vary slightly asa function of environment.


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Input: We investigate the gravitational wake due to, and dynamical friction on, aperturber moving on a circular orbit in a uniform gaseous medium using asemi-analytic method. This work is a straightforward extension of Ostriker(1999) who studied the case of a straight-line trajectory. The circular orbitcauses the bending of the wake in the background medium along the orbit,forming a long trailing tail. The wake distribution is thus asymmetric, givingrise to the drag forces in both opposite (azimuthal) and lateral (radial)directions to the motion of the perturber, although the latter does notcontribute to orbital decay much. For subsonic motion, the density wake with aweak tail is simply a curved version of that in Ostriker and does not exhibitthe front-back symmetry. The resulting drag force in the opposite direction isremarkably similar to the finite-time, linear-trajectory counterpart. On theother hand, a supersonic perturber is able to overtake its own wake, possiblymultiple times, and develops a very pronounced tail. The supersonic tailsurrounds the perturber in a trailing spiral fashion, enhancing the perturbeddensity at the back as well as far front of the perturber. We provide thefitting formulae for the drag forces as functions of the Mach number, whoseazimuthal part is surprisingly in good agreement with the Ostriker's formula,provided Vp t=2 Rp, where Vp and Rp are the velocity and orbital radius of theperturber, respectively.


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Input: We report on a theoretical derivation of the electronic dielectric responseof semiconductor nanocrystals using a tight-binding framework. Extending to thenanoscale the Hanke and Sham approach [Phys. Rev. B 12, 4501 (1975)] developedfor bulk semiconductors, we show how local field effects can be included in thestudy of confined systems. A great advantage of this scheme is that of beingformulated in terms of localized orbitals and thus it requires very fewcomputational resources and times. Applications to the optical and screeningproperties of semiconductor nanocrystals are presented here and discussed.Results concerning the absorption cross section, the static polarizability andthe screening function of InAs (direct gap) and Si (indirect gap) nanocrystalscompare well to both first principles results and experimental data. We alsoshow that the present scheme allows us to easily go beyond the continuumdielectric model, based on the Clausius-Mossotti equation, which is frequentlyused to include the nanocrystal surface polarization. Our calculations indicatethat the continuum dielectric model, used in conjunction with a size dependentdielectric constant, underestimates the nanocrystal polarizability, leading toexceedingly strong surface polarization fields.


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Input: We present in this paper three dynamic clustering techniques forObject-Oriented Databases (OODBs). The first two, Dynamic, Statistical &Tunable Clustering (DSTC) and StatClust, exploit both comprehensive usagestatistics and the inter-object reference graph. They are quite elaborate.However, they are also complex to implement and induce a high overhead. Thethird clustering technique, called Detection & Reclustering of Objects (DRO),is based on the same principles, but is much simpler to implement. These threeclustering algorithm have been implemented in the Texas persistent object storeand compared in terms of clustering efficiency (i.e., overall performanceincrease) and overhead using the Object Clustering Benchmark (OCB). The resultsobtained showed that DRO induced a lighter overhead while still achievingbetter overall performance.


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Input: In this paper we address the problem of finding the sensing capacity ofsensor networks for a class of linear observation models and a fixed SNRregime. Sensing capacity is defined as the maximum number of signal dimensionsreliably identified per sensor observation. In this context sparsity of thephenomena is a key feature that determines sensing capacity. Precluding the SNRof the environment the effect of sparsity on the number of measurementsrequired for accurate reconstruction of a sparse phenomena has been widelydealt with under compressed sensing. Nevertheless the development there wasmotivated from an algorithmic perspective. In this paper our aim is to derivethese bounds in an information theoretic set-up and thus provide algorithmindependent conditions for reliable reconstruction of sparse signals. In thisdirection we first generalize the Fano's inequality and provide lower bounds tothe probability of error in reconstruction subject to an arbitrary distortioncriteria. Using these lower bounds to the probability of error, we derive upperbounds to sensing capacity and show that for fixed SNR regime sensing capacitygoes down to zero as sparsity goes down to zero. This means thatdisproportionately more sensors are required to monitor very sparse events. Ournext main contribution is that we show the effect of sensing diversity onsensing capacity, an effect that has not been considered before. Sensingdiversity is related to the effective \emph{coverage} of a sensor with respectto the field. In this direction we show the following results (a) Sensingcapacity goes down as sensing diversity per sensor goes down; (b) Randomsampling (coverage) of the field by sensors is better than contiguous locationsampling (coverage).


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Input: We present numerical studies for finitely extensible nonlinear elastic (FENE)dumbbells which are dispersed in a turbulent plane shear flow at moderateReynolds number. The polymer ensemble is described on the mesoscopic level by aset of stochastic ordinary differential equations with Brownian noise. Thedynamics of the Newtonian solvent is determined by the Navier-Stokes equations.Momentum transfer of the dumbbells with the solvent is implemented by anadditional volume forcing term in the Navier-Stokes equations, such that bothcomponents of the resulting viscoelastic fluid are connected by a two-waycoupling. The dynamics of the dumbbells is given then by Newton's second law ofmotion including small inertia effects. We investigate the dynamics of the flowfor different degrees of dumbbell elasticity and inertia, as given byWeissenberg and Stokes numbers, respectively. For the parameters accessible inour study, the magnitude of the feedback of the polymers on the macroscopicproperties of turbulence remains small as quantified by the global energybudget and the Reynolds stresses. A reduction of the turbulent drag by up to20% is observed for the larger particle inertia. The angular statistics of thedumbbells shows an increasing alignment with the mean flow direction for both,increasing elasticity and inertia. This goes in line with a growing asymmetryof the probability density function of the transverse derivative of thestreamwise turbulent velocity component. We find that dumbbells get stretchedreferentially in regions where vortex stretching or bi-axial strain dominatethe local dynamics and topology of the velocity gradient tensor.


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Input: Inspired by a recent astro-ph posting, I propose a creation of an AlternativeHistory astro-ph archive (althistastro-ph). Such an archive would serve as afinal resting place for the various telescope (and possibly other) proposalsthat were not successful. As we all know, from both submitting proposals andalso from serving on various time allocation committees, many excellentproposals ``do not make it''. Creating such an AltHist archive would serve manygoals, including venting the frustration of the authors and also providingpossible amusement for the readers. These are worthy goals, but they alonewould not warrant creating such an archive. The truly useful role ofAltHistAstro-ph archive would be to match astronomers with unappreciated ideaswith other astronomers with underutilized resources, hopefully leading in somecases to resurrection of old proposals and resulting publications in theregular astro-ph archive. Given the possible danger of a low signal-to-noiseand possible confusion, a creation of a separate archive seems like a goodidea, although it should be noted that low signal-to-noise is achieved onastro-ph quite often already. Finally, I include my own excellent, but rejected(twice), HST proposal, as an example of a potential AltHistAstro-ph posting.


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Input: The $n$-dimensional complex hyperquadric is a compact complex algebraichypersurface defined by the quadratic equation in the $(n+1)$-dimensionalcomplex projective space, which is isometric to the real Grassmann manifold oforiented 2- planes and is a compact Hermitian symmetric space of rank 2. Inthis paper we study geometry of compact Lagrangian submanifolds in complexhyperquadrics from the viewpoint of the theory of isoparametric hypersurfacesin spheres. From this viewpoint we provide a classification theorem of compacthomogeneous Lagrangian submanifolds in complex hyperquadrics by using themoment map technique. Moreover we determine the Hamiltonian stability ofcompact minimal Lagrangian submanifolds embedded in complex hyperquadrics whichare obtained as Gauss images of isoparametric hypersurfaces in spheres with$g(=1,2,3)$ distinct principal curvatures.


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Input: There is a large literature devoted to the problem of finding an optimal(min-cost) prefix-free code with an unequal letter-cost encoding alphabet ofsize. While there is no known polynomial time algorithm for solving itoptimally there are many good heuristics that all provide additive errors tooptimal. The additive error in these algorithms usually depends linearly uponthe largest encoding letter size.  This paper was motivated by the problem of finding optimal codes when theencoding alphabet is infinite. Because the largest letter cost is infinite, theprevious analyses could give infinite error bounds. We provide a new algorithmthat works with infinite encoding alphabets. When restricted to the finitealphabet case, our algorithm often provides better error bounds than the bestprevious ones known.


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Input: We show that observations of high-redshift Ly-alpha emitters (LAEs) have thepotential to provide definitive evidence for reionization in the near future.Using 200 Mpc radiative transfer simulations, we calculate the effect thatpatchy reionization has on the line profile, on the luminosity function, and,most interestingly, on the clustering of emitters for several realistic modelsof reionization. Reionization increases the measured clustering of emitters,and we show that this enhancement would be essentially impossible to attributeto anything other than reionization. Our results motivate looking for thesignature of reionization in existing LAE data. We find that for stellarreionization scenarios the angular correlation function of the 58 LAEs in theSubaru Deep Field z = 6.6 photometric sample is more consistent with a fullyionized universe (mean volume ionized fraction x_i = 1) than a universe withx_i < 0.5 at >2-sigma confidence level. Measurements in the next year on Subaruwill increase their z = 6.6 LAE sample by a factor of five and tighten theselimits. If the clustering signature of reionization is detected in a LAEsurvey, a comparison with a Lyman-break or a H-alpha survey in the same fieldwould confirm the reionization hypothesis. We discuss the optimal LAE surveyspecifications for detecting reionization, with reference to upcoming programs.