18,218 research outputs found

    Effect of 6-day hypokinesia on oxygen metabolism indices in elderly and senile subjects

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    After a strict 6 day confinement to bed of elderly and senile subjects the oxygen supply of the subcutaneous cellular tissue was impaired, and the intensity of its tissue respiration was somewhat reduced. The vacat-oxygen of the blood and urine, the coefficient of incomplete oxidation, and the oxygen deficiency in the organism were increased

    Statistical characteristics of irreversible predictability time in regional ocean models

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    Probabilistic aspects of regional ocean model predictability is analyzed using the probability density function (PDF) of the irreversible predictability time (IPT) (called τ-PDF) computed from an unconstrained ensemble of stochastic perturbations in initial conditions, winds, and open boundary conditions. Two-attractors (a chaotic attractor and a small-amplitude stable limit cycle) are found in the wind-driven circulation. Relationship between attractor's residence time and IPT determines the τ-PDF for the short (up to several weeks) and intermediate (up to two months) predictions. The τ-PDF is usually non-Gaussian but not multi-modal for red-noise perturbations in initial conditions and perturbations in the wind and open boundary conditions. Bifurcation of τ-PDF occurs as the tolerance level varies. Generally, extremely successful predictions (corresponding to the τ-PDF's tail toward large IPT domain) are not outliers and share the same statistics as a whole ensemble of predictions

    Semileptonic decays of heavy mesons

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    The semileptonic and leptonic decays of heavy mesons are studied as a phenomenological application and exploration of a heavy-quark limit of Dyson-Schwinger equations. The single form factor, ξ(w)\xi(w), which characterises the semileptonic decay in this limit, is calculated and compares well with recent experimental extractions. We obtain a lower bound of 1/3 on the slope-parameter ρ2ξ(1)\rho^2 \equiv -\xi^\prime(1), which, in calculations with realistic input, is exceeded by a great deal: agreement with experimental data requiring ρ21.21.6\rho^2 \sim 1.2 - 1.6. The flavour and momentum dependence of the light-quark propagators has observable consequences.Comment: 11 pages, LaTeX, epsfig.sty, elsart.st

    Leptonic and semileptonic decays of heavy mesons

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    A heavy-quark limit of the Dyson-Schwinger equations is introduced and used in an exploratory study of leptonic and semileptonic decays of heavy mesons. The application of this framework to heavy-to-light semileptonic decays, which require a good knowledge of light-quark propagation characteristics and light-meson bound state amplitudes, is illustrated.Comment: 4 pages, 2 figures, Contribution to the IVth International Workshop on Progress in Heavy Quark Physics, 20-22 Sept. 1997, Rostoc

    Semiclassical dynamics of domain walls in the one-dimensional Ising ferromagnet in a transverse field

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    We investigate analytically and numerically the dynamics of domain walls in a spin chain with ferromagnetic Ising interaction and subject to an external magnetic field perpendicular to the easy magnetization axis (transverse field Ising model). The analytical results obtained within the continuum approximation and numerical simulations performed for discrete classical model are used to analyze the quantum properties of domain walls using the semiclassical approximation. We show that the domain wall spectrum shows a band structure consisting of 2SS non-intersecting zones.Comment: 15 pages, 9 figure
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