Non trivial generalizations of the Schwinger pair production result II

It is suggested that Schwinger's (1951) vacuum persistence probability against pair production by an intense but constant electric field is a very good approximation to the corresponding quantity if the field does not vary appreciably over distances less than m/e/E/5 pagesComment: 5 page

About the morphology of dwarf spheroidal galaxies and their dark matter content

The morphological properties of the Carina, Sculptor and Fornax dwarfs are investigated using new wide field data with a total area of 29 square degrees. The stellar density maps are derived, hinting that Sculptor possesses tidal tails indicating interaction with the Milky Way. Contrary to previous studies we cannot find any sign of breaks in the density profiles for the Carina and Fornax dwarfs. The possible existence of tidal tails in Sculptor and of King limiting radii in Fornax and Carina are used to derive global M/L ratios, without using kinematic data. By matching those M/L ratios to kinematically derived values we are able to constrain the orbital parameters of the three dwarfs. Fornax cannot have M/L smaller than 3 and must be close to its perigalacticon now. The other extreme is Sculptor that needs to be on an orbit with an eccentricity bigger than 0.5 to be able to form tidal tails despite its kinematic M/L.Comment: 9 pages, 7 figures, accepted by A&

Licensing Lawyers in the Modern Economy

This article explores a key question for the future of the legal profession: does a paradigm in which each individual state has exclusive control over the practice of law within its borders work in the marketplace of Friedman\u27s flat world ? Or in today\u27s global economy does state micromanagement of the legal profession so inure to the detriment of lawyers and clients that some form of national licensing is necessary

Licensing Lawyers in the Modern Economy

This article explores a key question for the future of the legal profession: does a paradigm in which each individual state has exclusive control over the practice of law within its borders work in the marketplace of Friedman\u27s flat world ? Or in today\u27s global economy does state micromanagement of the legal profession so inure to the detriment of lawyers and clients that some form of national licensing is necessary

Predictors of Exotic Plant Species in United States National Parks

Invasive species are recognized as a major threat to biodiversity. Understanding what factors facilitate invasion is of great conservation value, as this will allow for more specific and targeted conservation efforts related to non-native species. Knowledge of factors that contribute to invasion play an important role in conservation of particularly unique habitats, such as the iconic United States National Parks. Though National Parks have some legal protections against some forms of habitat degradation, they are still vulnerable to the introduction of non-natives. The purpose of this study is to characterize species invasion in National Parks and identify what environmental conditions may contribute to invasion on a national and regional level. We used plot-level and park-level data from 165 National Parks and National Historic Monuments throughout the United States to make correlations between the degree of invasion and predictor variables using a statistical regression analysis. We were unable to obtain a nationwide predictor of invasion, however were more successful on a regional basis. We concluded that the degree of human impact was the most important factor in predicting invasion. In addition, area of the park and precipitation were important factors correlated with invasion. Native species richness was correlated as well, however weakly. These results will be used to better assist in conservation efforts of National Parks in the future

Determination of complex dielectric functions of ion implanted and implanted‐annealed amorphous silicon by spectroscopic ellipsometry

Measuring with a spectroscopic ellipsometer (SE) in the 1.8–4.5 eV photon energy region we determined the complex dielectric function (ϵ = ϵ1 + iϵ2) of different kinds of amorphous silicon prepared by self‐implantation and thermal relaxation (500 °C, 3 h). These measurements show that the complex dielectric function (and thus the complex refractive index) of implanted a‐Si (i‐a‐Si) differs from that of relaxed (annealed) a‐Si (r‐a‐Si). Moreover, its ϵ differs from the ϵ of evaporated a‐Si (e‐a‐Si) found in the handbooks as ϵ for a‐Si. If we use this ϵ to evaluate SE measurements of ion implanted silicon then the fit is very poor. We deduced the optical band gap of these materials using the Davis–Mott plot based on the relation: (ϵ2E2)1/3 ∼ (E− Eg). The results are: 0.85 eV (i‐a‐Si), 1.12 eV (e‐a‐Si), 1.30 eV (r‐a‐Si). We attribute the optical change to annihilation of point defects

Measurement of thermal conductance of multilayer and other insulation materials Final report

Thermal conductance measurements of multilayer, aluminumized polymeric films for space suit insulation material