212,887 research outputs found

    Similarity Solutions of a Class of Perturbative Fokker-Planck Equation

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    In a previous work, a perturbative approach to a class of Fokker-Planck equations, which have constant diffusion coefficients and small time-dependent drift coefficients, was developed by exploiting the close connection between the Fokker-Planck equations and the Schrodinger equations. In this work, we further explore the possibility of similarity solutions of such a class of Fokker-Planck equations. These solutions possess definite scaling behaviors, and are obtained by means of the so-called similarity method

    Far-infrared spectroelectrochemistry: a study of linear molybdenum/iron/sulfur clusters

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    The far-infrared spectroelectrochemistry of linear M/Fe/S (M=Mo, W) complexes was investigated in methylene chloride and dichloroethane. With CsI as spectral windows, bands above 200 cm−1 can be observed in methylene chloride, except for a weak methylene chloride band at 450 cm−1. Substitution of dichloroethane for methylene chloride, solvents of nearly identical electrochemical properties, allows one to observe solute bands in the 450-cm−1 region. The far-infrared spectroelectrochemistry of [MoFe2S4Cl4]2− and its tungsten analogue was investigated. The disappearance of the oxidation bands and the appearance of bands due to the reduced product could be clearly observed. The origin of the vibrational bands could be clearly identified using 34S-substituted complexes. In addition to the far-infrared bands, the resonance Raman spectroelectrochemistry of the oxidized and reduced complex, along with the 34S-substituted complexes was obtained. Far-infrared and resonance Raman spectroelectrochemistry can be combined to understand the electrochemical mechanism of transition metal complexes. The far-infrared spectroelectrochemistry of [MoFe2S4Cl4]2− and its tungsten analogue was investigated. The disappearance of the initial bands and the appearance of bands due to the reduced product could be clearly observed. Resonance Raman spectroscopy and the use of 34S-substituted complexes were used for characterization of the reactant and products

    Statistical properties of the method of regularization with periodic Gaussian reproducing kernel

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    The method of regularization with the Gaussian reproducing kernel is popular in the machine learning literature and successful in many practical applications. In this paper we consider the periodic version of the Gaussian kernel regularization. We show in the white noise model setting, that in function spaces of very smooth functions, such as the infinite-order Sobolev space and the space of analytic functions, the method under consideration is asymptotically minimax; in finite-order Sobolev spaces, the method is rate optimal, and the efficiency in terms of constant when compared with the minimax estimator is reasonably high. The smoothing parameters in the periodic Gaussian regularization can be chosen adaptively without loss of asymptotic efficiency. The results derived in this paper give a partial explanation of the success of the Gaussian reproducing kernel in practice. Simulations are carried out to study the finite sample properties of the periodic Gaussian regularization.Comment: Published by the Institute of Mathematical Statistics (http://www.imstat.org) in the Annals of Statistics (http://www.imstat.org/aos/) at http://dx.doi.org/10.1214/00905360400000045

    Nonlocal Kirchhoff superlinear equations with indefinite nonlinearity and lack of compactness

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    We study the following Kirchhoff equation (1+bR3u2dx)Δu+V(x)u=f(x,u), xR3.- \left(1 + b \int_{\mathbb{R}^3} |\nabla u|^2 dx \right) \Delta u + V(x) u = f(x,u), \ x \in \mathbb{R}^3. A special feature of this paper is that the nonlinearity ff and the potential VV are indefinite, hence sign-changing. Under some appropriate assumptions on VV and ff, we prove the existence of two different solutions of the equation via the Ekeland variational principle and Mountain Pass Theorem

    Concrete: Potential material for Space Station

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    To build a permanent orbiting space station in the next decade is NASA's most challenging and exciting undertaking. The space station will serve as a center for a vast number of scientific products. As a potential material for the space station, reinforced concrete was studied, which has many material and structural merits for the proposed space station. Its cost-effectiveness depends on the availability of lunar materials. With such materials, only 1 percent or less of the mass of a concrete space structure would have to be transported from earth

    The net profitability of airline alliances using referential dollars

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    This study revises a previous research in which we analysed the net profitability of airline alliances but did not control for the impact of inflation on such profitability. Using the same methodology, 15 international airlines as subjects and their net financial results for a period of 11 years as primary research variables, we now compared the performance of airlines before and after joining their respective alliances using referential dollars (i.e., constant dollars with 2010 as base year) instead of nominal dollars. The results showed a similar deterioration in short-term net profits after joining an alliance as the previous study did, and a similar behaviour of statistics tests. Thus, the conclusion then achieved still stand after this revision

    Thermalization and temperature distribution in a driven ion chain

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    We study thermalization and non-equilibrium dynamics in a dissipative quantum many-body system -- a chain of ions with two points of the chain driven by thermal bath under different temperature. Instead of a simple linear temperature gradient as one expects from the classical heat diffusion process, the temperature distribution in the ion chain shows surprisingly rich patterns, which depend on the ion coupling rate to the bath, the location of the driven ions, and the dissipation rates of the other ions in the chain. Through simulation of the temperature evolution, we show that these unusual temperature distribution patterns in the ion chain can be quantitatively tested in experiments within a realistic time scale.Comment: 5 pages, 5 figure

    The Cardy-Verlinde Formula and Asymptotically Flat Charged Black Holes

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    We show that the modified Cardy-Verlinde formula without the Casimir effect term is satisfied by asymptotically flat charged black holes in arbitrary dimensions. Thermodynamic quantities of the charged black holes are shown to satisfy the energy-temperature relation of a two-dimensional CFT, which supports the claim in our previous work (Phys. Rev. D61, 044013, hep-th/9910244) that thermodynamics of charged black holes in higher dimensions can be effectively described by two-dimensional theories. We also check the Cardy formula for the two-dimensional black hole compactified from a dilatonic charged black hole in higher dimensions.Comment: 6 pages, LaTeX, references adde
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