Propagation of fronts in the Fisher-Kolmogorov equation with spatially varying diffusion

The propagation of fronts in the Fisher-Kolmogorov equation with spatially varying diffusion coefficients is studied. Using coordinate changes, WKB approximations, and multiple scales analysis, we provide an analytic framework that describes propagation of the front up to the minimum of the diffusion coefficient. We also present results showing the behavior of the front after it passes the minimum. In each case, we show that standard traveling coordinate frames do not properly describe front propagation. Lastly, we provide numerical simulations to support our analysis and to show, that around the minimum, the motion of the front is arrested on asymptotically significant timescales.Comment: 8 pages, 5 figure

Comparison of House Spraying and Insecticide-Treated Nets for Malaria Control.

The efficacies of using residual house spraying and insecticide-treated nets against malaria vectors are compared, using data from six recent comparisons in Africa, Asia and Melanesia. By all the entomological and malariological criteria recorded, pyrethroid-treated nets were at least as efficacious as house spraying with dichlorodiphenyltrichloroethane (DDT), malathion or a pyrethroid. However, when data from carefully monitored house spraying projects carried out between the 1950s and 1970s at Pare-Taveta and Zanzibar (United Republic of Tanzania), Kisumu (Kenya) and Garki (Nigeria) are compared with recent insecticide-treated net trials with apparently similar vector populations, the results with the insecticide-treated nets were much less impressive. Possible explanations include the longer duration of most of the earlier spraying projects and the use of non-irritant insecticides. Non-irritant insecticides may yield higher mosquito mortalities than pyrethroids, which tend to make insects leave the site of treatment (i.e. are excito-repellent). Comparative tests with non-irritant insecticides, including their use on nets, are advocated. The relative costs and sustainability of spraying and of insecticide-treated net operations are briefly reviewed for villages in endemic and epidemic situations and in camps for displaced populations. The importance of high population coverage is emphasized, and the advantages of providing treatment free of charge, rather than charging individuals, are pointed out

Squamous cell carcinoma of the dorsal hands and feet after repeated exposure to ultraviolet nail lamps

Gel nails are a common artificial nail option. Ultraviolet (UV) nail lamps are commonly used to cure gel nails. Ultraviolet A radiation is a known mutagen that penetrates into the nail bed. Although previously reported, the role of UV nail lamps in the carcinogenesis of both keratinocyte carcinoma and melanoma remains controversial. Herein, we report a patient taking the photosensitizing agent hydrochlorothiazide who developed numerous squamous cell carcinomas on the dorsal hands and feet with a 10-year history of UV nail light exposure every 2-3 weeks

Partnerships for education, well-being and work : models of university service in the community

"This five month multi-perspective study, commissioned by the Higher Education Funding Council for England (HEFCE), investigated the nature, forms and practices of three partnership enterprises between the University of Nottingham and its local schools and communities" -- page vii

Seasonal Patterns of Microhabitat Selection by a Sub-tropical Whip Spider, Phrynus longipes, in the Luquillo Experimental Forest, Puerto Rico

Phrynus longipes (Pocock 1894) is a top predator among arboreal invertebrates in the Luquillo Mountains of Puerto Rico, but many aspects of its ecology remain poorly understood. We sampled four of the most abundant tree species in the Luquillo Mountains during the dry and wet seasons of 2008 to evaluate microhabitat preferences of this species. In the dry season, P. longipes occurred significantly less frequently on a palm, Prestoea acuminata var. montana (Arecaceae), than the other tree species. Carapace length and the diameter of the tree on which an individual was found were positively correlated, suggesting competition for substrates. Microhabitat selection shifted in the wet season. Individuals occurred as frequently on P. acuminata as on any other species. The seasonal shift in substrate use could result from altered distribution or abundance of prey, an ontogenetic shift in substrate preference or greater competition arising from an increased abundance of P. longipes

Handgun carrying among youth in the United States

Despite a wealth of research finding that adolescents who carry handguns are involved in risky behaviors, there has been little exploration into the heterogeneity of this behavior. Using a pooled sample of 12- to 17-year-olds from the National Study on Drug Use and Health who report past-year handgun carrying (N = 7,872), this study identified four subgroups of handgun carriers: low risk (n = 3,831; 47.93%), alcohol and marijuana users (n = 1,591; 20.16%), fighters (n = 1,430; 19.40%), and severe externalizers (n = 1,020, 12.51%). These subgroups differed on demographic, behavioral, and psychosocial characteristics. Findings are discussed in light of prevention and focused deterrence

Linear and nonlinear traveling edge waves in optical honeycomb lattices

Traveling unidirectional localized edge states in optical honeycomb lattices are analytically constructed. They are found in honeycomb arrays of helical waveguides designed to induce a periodic pseudomagnetic field varying in the direction of propagation. Conditions on whether a given pseudofield supports a traveling edge mode are discussed; a special case of the pseudofields studied agrees with recent experiments. Interesting classes of dispersion relations are obtained. Envelopes of nonlinear edge modes are described by the classical one-dimensional nonlinear Schrödinger equation along the edge. Nonlinear states termed edge solitons are predicted analytically and are found numerically