87,392 research outputs found
The operational processing of wind estimates from cloud motions: Past, present and future
Current NESS winds operations provide approximately 1800 high quality wind estimates per day to about twenty domestic and foreign users. This marked improvement in NESS winds operations was the result of computer techniques development which began in 1969 to streamline and improve operational procedures. In addition, the launch of the SMS-1 satellite in 1974, the first in the second generation of geostationary spacecraft, provided an improved source of visible and infrared scanner data for the extraction of wind estimates. Currently, operational winds processing at NESS is accomplished by the automated and manual analyses of infrared data from two geostationary spacecraft. This system uses data from SMS-2 and GOES-1 to produce wind estimates valid for 00Z, 12Z and 18Z synoptic times
Properties of the mixed μ problem and its bounds
Upper and lower bounds for the mixed μ problem have recently been developed, and here we examine the relationship of these bounds to each other and to μ. A number of interesting properties are developed and the implications of these properties for the robustness analysis of linear systems and the development of practical computation schemes are discussed. In particular we find that current techniques can only guarantee easy computation for large problems when μ equals its upper bound, and computational complexity results prohibit this possibility for general problems. In this context we present some special cases where computation is easy and make some direct comparisons between mixed μ and “Kharitonov-type” analysis methods
Phonon Anomalies Induced by Superconductivity
We calculate the electronic polarizability in the superconducting state near
extremum vectors of the Fermi surface. A pole appears in the
polarizability at frequencies near the superconducting gap
which leads to a sharp peak at just below in the lattice
vibrations near . A second order transition to a charge density
wave state below the superconducting transition is shown to be unlikely. The
results are compared with the recent inelastic neutron scattering measurements
in compounds, , or .Comment: 11 pages, RevTex, 3 Postscript figures. Corrections and significant
additions in revisio
Matching Excluded Volume Hadron Resonance Gas Models and Perturbative QCD to Lattice Calculations
We match three hadronic equations of state at low energy densities to a
perturbatively computed equation of state of quarks and gluons at high energy
densities. One of them includes all known hadrons treated as point particles,
which approximates attractive interactions among hadrons. The other two
include, in addition, repulsive interactions in the form of excluded volumes
occupied by the hadrons. A switching function is employed to make the crossover
transition from one phase to another without introducing a thermodynamic phase
transition. A chi-square fit to accurate lattice calculations with temperature
MeV determines the parameters. These parameters quantify the
behavior of the QCD running gauge coupling and the hard core radius of protons
and neutrons, which turns out to be fm. The most physically
reasonable models include the excluded volume effect. Not only do they include
the effects of attractive and repulsive interactions among hadrons, but they
also achieve better agreement with lattice QCD calculations of the equation of
state. The equations of state constructed in this paper do not result in a
phase transition, at least not for the temperatures and baryon chemical
potentials investigated. It remains to be seen how well these equations of
state will represent experimental data on high energy heavy ion collisions when
implemented in hydrodynamic simulations.Comment: 19 pages, 9 figure
The development of aerodynamic uncertainties for the space shuttle orbiter
The Shuttle Program development schedule and the management decision to perform an orbital, manned mission on the first launch resulted in a requirement to develop realistic aerodynamic uncertainties for the preflight aerodynamic predictions. This paper addresses the methodology in developing two types of aerodynamic uncertainties. One involves the ability to reproduce aerodynamic results between various wind tunnel tests. The second addresses the difference between preflight aerodynamic predictions and flight results derived from analysis of past aircraft programs. Both types of uncertainties for pitching moment, lateral-directional stability, rudder power, and aileron power are presented. In addition, the application of uncertainties to flight control design and fight test planning is briefly reviewed
Net Baryon Fluctuations from a Crossover Equation of State
We have constructed an equation of state which smoothly interpolates between
an excluded volume hadron resonance gas at low energy density to a plasma of
quarks and gluons at high energy density. This crossover equation of state
agrees very well with lattice calculations at both zero and nonzero baryon
chemical potential. We use it to compute the variance, skewness, and kurtosis
of fluctuations of baryon number, and compare to measurements of proton number
fluctuations in central Au-Au collisions as measured by the STAR collaboration
in a beam energy scan at the Relativistic Heavy Ion Collider. The crossover
equation of state can reproduce the data if the fluctuations are frozen out at
temperatures well below than the average chemical freeze-out.Comment: 5 pages, 7 figures. arXiv admin note: substantial text overlap with
arXiv:1506.0340
Further studies of X-ray structure of the Perseus cluster
The X-ray sources in the Perseus cluster have been studied by many authors. Available data on the spatial and spectral distributions are examined and summarized. Based on these observations, a consistent model is proposed for the production of X-rays and gamma-rays in the region around NGC 1275. It is shown that good agreement with observations is obtained by assuming the emission of soft X-rays for thermal bremsstrahlung and of hard X-rays and gamma-rays from the inverse Compton process
A Candidate Subspecies Discrimination System Involving a Vomeronasal Receptor Gene with Different Alleles Fixed in \u3ci\u3eM. m. domesticus\u3c/i\u3e and \u3ci\u3eM. m. musculus\u3c/i\u3e
Assortative mating, a potentially efficient prezygotic reproductive barrier, may prevent loss of genetic potential by avoiding the production of unfit hybrids (i.e., because of hybrid infertility or hybrid breakdown) that occur at regions of secondary contact between incipient species. In the case of the mouse hybrid zone, where two subspecies of Mus musculus (M. m. domesticus and M. m. musculus) meet and exchange genes to a limited extent, assortative mating requires a means of subspecies recognition. We based the work reported here on the hypothesis that, if there is a pheromone sufficiently diverged between M. m. domesticus and M. m. musculus to mediate subspecies recognition, then that process must also require a specific receptor(s), also sufficiently diverged between the subspecies, to receive the signal and elicit an assortative mating response. We studied the mouse V1R genes, which encode a large family of receptors in the vomeronasal organ (VNO), by screening Perlegen SNP data and identified one, Vmn1r67, with 24 fixed SNP differences most of which (15/24) are nonsynonymous nucleotide substitutions between M. m. domesticus and M. m. musculus. We observed substantial linkage disequilibrium (LD) between Vmn1r67 and Abpa27, a mouse salivary androgen-binding protein gene that encodes a proteinaceous pheromone (ABP) capable of mediating assortative mating, perhaps in conjunction with its bound small lipophilic ligand. The LD we observed is likely a case of association rather than residual physical linkage from a very recent selective sweep, because an intervening gene, Vmn1r71, shows significant intra(sub)specific polymorphism but no inter(sub)specific divergence in its nucleotide sequence. We discuss alternative explanations of these observations, for example that Abpa27 and Vmn1r67 are coevolving as signal and receptor to reinforce subspecies hybridization barriers or that the unusually divergent Vmn1r67 allele was not a product of fast positive selection, but was derived from an introgressed allele, possibly from Mus spretus
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