A Stochastic Model for Dielectric Breakdown in Thin Capacitors

A nontrivial two-dimensional stochastic model for dielectric breakdown within a parallel plate capacitor is presented for the first time. The model has been used to determine geometric properties of parallel plate discharges. Comparisons are made between these properties and known fractal properties of electrostatic discharges within cylindrical geometries. As the spacing between the plates of a capacitor increases, the value of the fractal dimension of the associated discharge structure increases from the minimum value of unity and approaches the limiting value corresponding to the case of infinite spacing. For any given spacing, this fractal exponent is equal to the exponent of first passage time for the discharge pattern to reach a given height. A study of various power law relationships governing the breakdown may provide insight into the breakdown mechanism and electrical insulating quality of various materials. The model is applicable to the breakdown of thin insulating layers of metal-oxide-semiconductor devices

Overt Attention and Context Factors: The Impact of Repeated Presentations, Image Type, and Individual Motivation

The present study investigated the dynamic of the attention focus during observation of different categories of complex scenes and simultaneous consideration of individuals' memory and motivational state. We repeatedly presented four types of complex visual scenes in a pseudo-randomized order and recorded eye movements. Subjects were divided into groups according to their motivational disposition in terms of action orientation and individual rating of scene interest

''We're gators...not just gator fans'' : serious leisure and university of Florida football

On utilise le concept de loisir sérieux (Stebbins, 1979 ; 1992) pour étudier les significations, les rites et les pratiques des supporteurs fans du club de football de l'université de Floride (Gators)

Acute Toxicity Prediction to Threatened and Endangered Species Using Interspecies Correlation Estimation (ICE) Models

Evaluating contaminant sensitivity of threatened and endangered (listed) species and protectiveness of chemical regulations often depends on toxicity data for commonly tested surrogate species. The U.S. EPA’s Internet application Web-ICE is a suite of Interspecies Correlation Estimation (ICE) models that can extrapolate species sensitivity to listed taxa using least-squares regressions of the sensitivity of a surrogate species and a predicted taxon (species, genus, or family). Web-ICE was expanded with new models that can predict toxicity to over 250 listed species. A case study was used to assess protectiveness of genus and family model estimates derived from either geometric mean or minimum taxa toxicity values for listed species. Models developed from the most sensitive value for each chemical were generally protective of the most sensitive species within predicted taxa, including listed species, and were more protective than geometric means models. ICE model estimates were compared to HC5 values derived from Species Sensitivity Distributions for the case study chemicals to assess protectiveness of the two approaches. ICE models provide robust toxicity predictions and can generate protective toxicity estimates for assessing contaminant risk to listed species