Local Volume Effects in the Generalized Pseudopotential Theory

The generalized pseudopotential theory (GPT) is a powerful method for deriving real-space transferable interatomic potentials. Using a coarse-grained electronic structure, one can explicitly calculate the pair ion-ion and multi-ion interactions in simple and transition metals. Whilst successful in determining bulk properties, in central force metals the GPT fails to describe crystal defects for which there is a significant local volume change. A previous paper [PhysRevLett.66.3036 (1991)] found that by allowing the GPT total energy to depend upon some spatially-averaged local electron density, the energetics of vacancies and surfaces could be calculated within experimental ranges. In this paper, we develop the formalism further by explicitly calculating the forces and stress tensor associated with this total energy. We call this scheme the adaptive GPT (aGPT) and it is capable of both molecular dynamics and molecular statics. We apply the aGPT to vacancy formation and divacancy binding in hcp Mg and also calculate the local electron density corrections to the bulk elastic constants and phonon dispersion for which there is refinement over the baseline GPT treatment.Comment: 11 pages, 6 figure

Simultaneous measurement of multiple parameters of a subwavelength structure based on the weak value formalism

A mathematical extension of the weak value formalism to the simultaneous measurement of multiple parameters is presented in the context of an optical focused vector beam scatterometry experiment. In this example, preselection and postselection are achieved via spatially-varying polarization control, which can be tailored to optimize the sensitivity to parameter variations. Initial experiments for the two-parameter case demonstrate that this method can be used to measure physical parameters with resolutions at least 1000 times smaller than the wavelength of illumination

Hamiltonian Theory of Adiabatic Motion of Relativistic Charged Particles

A general Hamiltonian theory for the adiabatic motion of relativistic charged particles confined by slowly-varying background electromagnetic fields is presented based on a unified Lie-transform perturbation analysis in extended phase space (which includes energy and time as independent coordinates) for all three adiabatic invariants. First, the guiding-center equations of motion for a relativistic particle are derived from the particle Lagrangian. Covariant aspects of the resulting relativistic guiding-center equations of motion are discussed and contrasted with previous works. Next, the second and third invariants for the bounce motion and drift motion, respectively, are obtained by successively removing the bounce phase and the drift phase from the guiding-center Lagrangian. First-order corrections to the second and third adiabatic invariants for a relativistic particle are derived. These results simplify and generalize previous works to all three adiabatic motions of relativistic magnetically-trapped particles.Comment: 20 pages, LaTeX, to appear in Physics of Plasmas (Aug, 2007

Application of Osteopathic Manipulative Medicine to Ameliorate Sepsis Induced Ileus

Graduate Basi

Microwave ISM Emission in the Green Bank Galactic Plane Survey: Evidence for Spinning Dust

We observe significant dust-correlated emission outside of H II regions in the Green Bank Galactic Plane Survey (-4 < b < 4 degrees) at 8.35 and 14.35 GHz. The rising spectral slope rules out synchrotron and free-free emission as majority constituents at 14 GHz, and the amplitude is at least 500 times higher than expected thermal dust emission. When combined with the Rhodes (2.326 GHz), and WMAP (23-94 GHz) data it is possible to fit dust-correlated emission at 2.3-94 GHz with only soft synchrotron, free-free, thermal dust, and an additional dust-correlated component similar to Draine & Lazarian spinning dust. The rising component generally dominates free-free and synchrotron for \nu >~ 14 GHz and is overwhelmed by thermal dust at \nu > 60 GHz. The current data fulfill most of the criteria laid out by Finkbeiner et al. (2002) for detection of spinning dust.Comment: ApJ in press. 26 pages, 11 figures, figures jpeg compressed to save spac

A Numerical Approach for Determining the Resistance of Fine Mesh Filters

Characterizing the resistance of mesh filters, in terms of the pressure drop as a function of flow velocity, is an important part of modeling any filtration process. Most commonly, filters are characterized experimentally, which can be costly and time consuming. This motivates the need for a generalized numerical approach for characterizing the resistance of mesh filters based on the flow through a representative segment of the filter. There is uncertainty, however, in the correct specification of boundary conditions such that the numerical results for flow through the small segment match the overall behaviour of the filter. In this work, an experimentally validated numerical approach is developed by examining the velocity and turbulence intensity experienced across the filter. It has been shown that the flow resistance results are not sensitive to the turbulence intensity, but depend greatly on the imposed flow velocity. Specifying the peak velocity as the boundary condition in the filter simulations resulted in a good match with experiments, while using the bulk velocity was not able to reproduce the experimental results.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author