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Full-Text Articles in Physics

Gravitational Synchrotron Radiation From Cosmic Strings, Alan Cresswell, Robert L. Zimmerman Oct 1990

Gravitational Synchrotron Radiation From Cosmic Strings, Alan Cresswell, Robert L. Zimmerman

Physics Faculty Publications and Presentations

This work studies the gravitational synchrotron radiation emitted from arbitrary cusps of cosmic strings. The results are expressed in terms of four parameters describing the motion of such a cusp. The power spectrum is derived for cusps moving at unit velocity. By using a phenomenological approach the authors also derive the power emitted when the radiation reaction on the cusps is taken into account. In both cases, the synchrotron nature of the radiation produces a power spectrum emitted in a narrow forward cone. If cosmic strings do exist, the radiation emitted by their cusps would seem to be a potential ...


Reduced Form For Coulomb-Wave Multicenter Integrals, Jack C. Straton Jul 1990

Reduced Form For Coulomb-Wave Multicenter Integrals, Jack C. Straton

Physics Faculty Publications and Presentations

In a previous paper [J. C. Straton, Phys. Rev. A 41, 71 (1990)] an integro-differential transform was introduced and utilized to obtain the analytically reduced form for multicenter integrals composed of general-state hydrogenic orbitals, Yukawa or Coulomb potentials, and plane waves. The present paper extends this result to include Coulomb waves.


Supercurrent Tunneling Between Conventional And Unconventional Superconductors: A Ginzburg-Landau Approach, S. K. Yip, O. F. De Alcantara Bonfim, P. Kumar Jun 1990

Supercurrent Tunneling Between Conventional And Unconventional Superconductors: A Ginzburg-Landau Approach, S. K. Yip, O. F. De Alcantara Bonfim, P. Kumar

Physics Faculty Publications and Presentations

We investigate the Josephson tunneling between a conventional and an unconventional superconductor via a Ginzburg-Landau theory. This approach allows us to write down the general form of the Josephson coupling between the two superconductors, and to see which terms are forbidden or allowed by spatial symmetries. The time-reversal symmetry is also considered. We discuss the current-phase relationships, magnetic, and ac effects if we just include this direct coupling to the unconventional superconductor. In addition we consider the Josephson coupling between two short-coherence-length superconductors, extending the work of Deutscher and Müller (DM) to a finite-current calculation. We find that the critical ...


Decay Of Molecules At Spherical Surfaces: Nonlocal Effects, P.T. Leung Apr 1990

Decay Of Molecules At Spherical Surfaces: Nonlocal Effects, P.T. Leung

Physics Faculty Publications and Presentations

The decay rates for molecules in the vicinity of a metallic sphere are investigated in a phenomenological approach for very close molecule-surface distances d. The Fuchs-Claro model [Phys. Rev. B 35, 3722 (1987)] is adopted to describe the polarizability of the sphere with the nonlocal dielectric response being accounted for within the hydrodynamic description. The results show significant differences when compared with those obtained previously within a local description for dlsim50 Aring, with extra resonances observed in the high-frequency regime, a phenomenon similar to that noted previously by Ruppin (1982), in his calculation of the extinction cross section for such ...


Self-Consistent Effective Binary Diffusion In Multicomponent Gas Mixtures, John D. Ramshaw Jan 1990

Self-Consistent Effective Binary Diffusion In Multicomponent Gas Mixtures, John D. Ramshaw

Physics Faculty Publications and Presentations

The correct treatment of diffusion in multicomponent gas mixtures requires solution of a linear system of equations for the diffusive mass fluxes relative to the mass-averaged velocity of the mixture. Effective binary diffusion approximations are often used to avoid solving this system. These approximations are generally internally inconsistent in the sense that the approximate diffusion fluxes do not properly sum to zero. The origin of this inconsistency is identified, and a general procedure for removing it is presented. This procedure applies equally to concentration, forced, pressure, and thermal diffusion, either separately or in combination. It is used to obtain a ...


Reduced Form For The General-State Multicenter Integral From An Integro-Differential Transform, Jack C. Straton Jan 1990

Reduced Form For The General-State Multicenter Integral From An Integro-Differential Transform, Jack C. Straton

Physics Faculty Publications and Presentations

In a previous paper Gaussian transforms were utilized to obtain the analytically reduced form for the class of multicenter integrals containing a product of hydrogenic orbitals for s states, Yukawa or Coulomb potentials, and plane waves. In the present paper a related transformation is developed for nonspherical functions, leading to the reduced form for multicenter integrals that include hydrogenic orbitals representing states of arbitrary angular momentum.