Green's function for the Relativistic Coulomb System via Sum Over Perturbation Series

We evaluate the Green's function of the D-dimensional relativistic Coulomb system via sum over perturbation series which is obtained by expanding the exponential containing the potential term $V({\bf x)}$ in the path integral into a power series. The energy spectra and wave functions are extracted from the resulting amplitude.Comment: 13 pages, ReVTeX, no figure

Similarity Solutions of a Class of Perturbative Fokker-Planck Equation

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

Net profitability of airline alliances, an empirical study

This study examines the net return for airlines before and after joining an alliance. The research database was compiled from ICAOData, and comprised 15 international airlines as subjects and their net financial results for a period of 11 years as primary research variables. Two variables, the averages of five and three years net performance before joining an alliance, were tested against another variable, the average net performance five years after joining the alliance. Results show a deterioration of net profits after joining an alliance, although this trend was only significant when comparing performance over the short-term. However, the performance of American airlines accounted for most of this trend, which may have being partly affected by the consequences of September 11 2001

Hyperspherical Close-Coupling Calculation of D-wave Positronium Formation and Excitation Cross Sections in Positron-Hydrogen Scattering

Hyperspherical close-coupling method is used to calculate the elastic, positronium formation and excitation cross sections for positron collisions with atomic hydrogen at energies below the H(n=4) threshold for the J=2 partial wave. The resonances below each inelastic threshold are also analyzed. The adiabatic hyperspherical potential curves are used to identify the nature of these resonances.Comment: 12 pages(in a TeX file) +8 Postscript figure

Thermalization and temperature distribution in a driven ion chain

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

Concrete: Potential material for Space Station

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

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

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