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

Effects of environmentally realistic daily temperature fluctuations on contaminant toxicity in aquatic ecosystems

Temperature is one of the most critical environmental factors that can influence an organism’s metabolism as well as impact toxicokinetics and toxicodynamics. Most studies investigating the effects of temperature on toxicity do not incorporate realistic daily temperature fluctuations. These fluctuations may be important for high elevation/arid aquatic ecosystems, which experience large changes in daily temperatures. Temperature and contaminants can also affect important ecosystem processes like organic matter decomposition via impacts on microbial communities and the shredding invertebrates responsible for breakdown of this material. The objectives of this research were to: 1) assess how realistic daily temperature fluctuations, based on field collected playa wetland temperatures, impact toxicity of pesticides to aquatic invertebrates, 2) determine how pharmaceutical-fungicide mixtures and temperature regimes affect leaf decomposition processes, 3) examine toxicity of the fungicide pyraclostrobin to the shredding amphipod Hyalella azteca and effects on leaf processing and the microbial community, and 4) assess how daily temperature regimes impact growth and development of larval Mexican spadefoot toads (Spea multiplicata). Results indicated that toxicity of pesticides under fluctuating daily temperature cycles can differ compared to a constant temperature or a temperature regime altered based on climate change predictions. There was no clear trend of mixture effects for triclosan, ciprofloxacin, or chlorothalonil, on H. azteca or leaf processing, but ciprofloxacin may have the greatest effect. Pyraclostrobin was toxic to H. azteca and caused reductions in leaf processing, and some effects also depended on temperature regime. However, at environmentally relevant concentrations of pyraclostrobin there were limited effects on H. azteca, fungal biomass and microbial community function. In general growth of S. multiplicata did not differ between temperature regimes, and this may indicate natural adaptation to thermally heterogeneous environments. Therefore, effects of realistic daily temperature fluctuations on ecologically relevant responses may be complex, but are important for assessing how risk of contaminants may be altered under future climate change scenarios, especially for organisms that inhabit thermally variable environments

''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)

Destination Management Organizations and Tourism Crisis Management Plans in Florida

Destination management organizations (DMOs) at the local level are at the forefront of crisis management planning for the tourism industry. Previous studies have highlighted the importance of the role of DMOs in the event of a crisis. While crisis preparedness of an organization is based on the respective crisis plans, minimal attention has been given to the analysis of DMO's crisis management plans in the US. The nature of organizational crisis plans can be analyzed through the use of multiple variables. This study examines DMO crisis plans in Florida that are designed specifically for the tourism industry, and are analyzed based on geographical location, bed tax revenues, and the number of employees. The results indicate that revenues play a significant role in determining the level of tourism crisis management preparedness within DMOs.</jats:p