17,519 research outputs found

    Patterns of behavior in lodgings exposed to traffic noise

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    Threshold values for public services interferent on the attenuation to noise nuisance were defined. Daily life at home was described and collected on the use of residences, the effects of noise on health and sleep, and the incidence of running away from home. A correlation was made with the equipment and noise insulation of homes. It is shown that there are behavior patterns in the modification of considerable manner in the way of life for people who live in apartments and in individual houses, above 66 dB during daytime

    Numerical radiative transfer with state-of-the-art iterative methods made easy

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    This article presents an on-line tool (rttools.irap.omp.eu) and its accompanying software ressources for the numerical solution of basic radiation transfer out of local thermodynamic equilibrium (LTE). State-of-the-art stationary iterative methods such as Accelerated Λ\Lambda-Iteration and Gauss-Seidel schemes, using a short characteristics-based formal solver are used. We also comment on typical numerical experiments associated to the basic non-LTE radiation problem. These ressources are intended for the largest use and benefit, in support to more classical radiation transfer lectures usually given at the Master level.Comment: 8 pages, 5 figures, accepted for Eur. J. Phys. - see also (and use!) http://rttools.irap.omp.e

    Effect of habituation on the susceptibility of the rat to restraint ulcers

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    The frequency and gravity of restraint ulcers were found to significantly diminish in rats previously exposed to brief periods of immobilization. The rats' becoming habituated to restraint conditions probably explains this phenomenon

    O/Fe in metal-poor main sequence and subgiant stars

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    A study of the O/Fe ratio in metal-poor main sequence and subgiant stars is presented using the [OI] 6300A line, the OI 7774A triplet, and a selection of weak FeII lines observed on high-resolution spectra acquired with the VLT UVES spectrograph. The [OI] line is detected in the spectra of 18 stars with -0.5 < [Fe/H] < -2.4, and the triplet is observed for 15 stars with [Fe/H] ranging from -1.0 to -2.7. The abundance analysis was made first using standard model atmospheres taking into account non-LTE effects on the triplet: the [OI] line and the triplet give consistent results with [O/Fe] increasing quasi-linearly with decreasing [Fe/H] reaching [O/Fe] ~ +0.7 at [Fe/H] = -2.5. When hydrodynamical model atmospheres representing stellar granulation in dwarf and subgiant stars replace standard models, the [O/Fe] from the [OI] and FeII lines is decreased by an amount which increases with decreasing [Fe/H]. The [O/Fe] vs [Fe/H] relation remains quasi-linear extending to [O/Fe] ~ +0.5 at [Fe/H] = -2.5, but with a tendency of a plateau with [O/Fe] ~ +0.3 for -2.0 < [Fe/H] < -1.0, and a hint of cosmic scatter in [O/Fe] at [Fe/H] ~ -1.0. Use of the hydrodynamical models disturbs the broad agreement between the oxygen abundances from the [OI], OI, and OH lines, but 3D non-LTE effects may serve to erase these differences.Comment: ps file, 18 pages (including 10 figures) - Accepted for publication in A&

    Modelling persistence in annual Australia point rainfall

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    Annual rainfall time series for Sydney from 1859 to 1999 is analysed. Clear evidence of nonstationarity is presented, but substantial evidence for persistence or hidden states is more elusive. A test of the hypothesis that a hidden state Markov model reduces to a mixture distribution is presented. There is strong evidence of a correlation between the annual rainfall and climate indices. Strong evidence of persistence of one of these indices, the Pacific Decadal Oscillation (PDO), is presented together with a demonstration that this is better modelled by fractional differencing than by a hidden state Markov model. It is shown that conditioning the logarithm of rainfall on PDO, the Southern Oscillation index (SOI), and their interaction provides realistic simulation of rainfall that matches observed statistics. Similar simulation models are presented for Brisbane, Melbourne and Perth.</p> <p style='line-height: 20px;'><b>Keywords: </b>Hydrological persistence,hidden state Markov models, fractional differencing, PDO, SOI, Australian rainfall</p

    Solitons from a direct point of view: padeons

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    AbstractA systematic approach to soliton interaction is presented in terms of a particular class of solitary waves (padeons) which are linear fractions with respect to the nonlinearity parameter ϵ. A straightforward generalization of the padeon to higher order rational fractions (multipadeon) yields a natural ansatz for N-soliton solutions. This ansatz produces multisoliton formulas in terms of an ‘interaction matrix’ A. The structure of the matrix gives some insight into the hidden IST-properties of a familiar set of ‘integrable’ equations (KdV, Boussinesq, MKdV, sine-Gordon, nonlinear Schrödinger). The analysis suggests a ‘padeon’ working definition of the soliton, leading to an explicit set of necessary conditions on the padeon equation

    Sub-gap conductance in ferromagnetic-superconducting mesoscopic structures

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    We study the sub-gap conductance of a ferromagnetic mesoscopic region attached to a ferromagnetic and a superconducting electrode by means of tunnel junctions. In the absence of the exchange field, the ratio r=γ/ϵTr= \gamma / \epsilon_T of the two tunnel junction resistances determines the behaviour of the sub-gap conductance which possesses a zero-bias peak for r≫1r\gg 1 and for r≪1r\ll 1 a peak at finite voltage. We show that the inclusion of the exchange field leads to a peak splitting for r≪1r\ll 1, while it shifts the zero-bias anomaly to finite voltages for r≫1r\gg 1.Comment: 5 pages revte

    Quantum Spin Fluctuations as a Source of Long-Range Proximity Effects in Diffusive Ferromagnet-Superconductor Structures

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    We show that quantum spin fluctuations in inhomogeneous ferromagnets drastically affect the Andreev reflection of electrons and holes at a ferromagnet-superconductor interface. As a result a strong long-range proximity effect appears, associated with electron-hole spin triplet correlations and persisting on a lenght scale typical for non-magnetic materials, but anomalously large for ferromagnets.Comment: 4 pages, 2 figure

    Suppression of Giant Magnetoresistance by a superconducting contact

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    We predict that current perpendicular to the plane (CPP) giant magnetoresistance (GMR) in a phase-coherent magnetic multilayer is suppressed when one of the contacts is superconducting. This is a consequence of a superconductivity-induced magneto-resistive (SMR) effect, whereby the conductance of the ferromagnetically aligned state is drastically reduced by superconductivity. To demonstrate this effect, we compute the GMR ratio of clean (Cu/Co)_nCu and (Cu/Co)_nPb multilayers, described by an ab-initio spd tight binding Hamiltonian. By analyzing a simpler model with two orbitals per site, we also show that the suppression survives in the presence of elastic scattering by impurities.Comment: 5 pages, 4 figures. Submitted to PR
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