Nothing a Hot Bath Won't Cure: Infection Rates of Amphibian Chytrid Fungus Correlate Negatively with Water Temperature under Natural Field Settings

Dramatic declines and extinctions of amphibian populations throughout the world have been associated with chytridiomycosis, an infectious disease caused by the pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd). Previous studies indicated that Bd prevalence correlates with cooler temperatures in the field, and laboratory experiments have demonstrated that Bd ceases growth at temperatures above 28°C. Here we investigate how small-scale variations in water temperature correlate with Bd prevalence in the wild. We sampled 221 amphibians, including 201 lowland leopard frogs (Rana [Lithobates] yavapaiensis), from 12 sites in Arizona, USA, and tested them for Bd. Amphibians were encountered in microhabitats that exhibited a wide range of water temperatures (10–50°C), including several geothermal water sources. There was a strong inverse correlation between the water temperature in which lowland leopard frogs were captured and Bd prevalence, even after taking into account the influence of year, season, and host size. In locations where Bd was known to be present, the prevalence of Bd infections dropped from 75–100% in water <15°C, to less than 10% in water >30°C. A strong inverse correlation between Bd infection status and water temperature was also observed within sites. Our findings suggest that microhabitats where water temperatures exceed 30°C provide lowland leopard frogs with significant protection from Bd, which could have important implications for disease dynamics, as well as management applications

Сurrent problems in energetic materials ignition studies

Several problems of ignition of energetic materials (EMs), which are able to burn in the absence of an external oxidizer, are discussed in this chapter. Scientific investigation of the EMs ignition has started at the end 1930th when the first field missiles (Katyusha) were developed in the USSR. Later the investigations were actively performed in USA and Europe but despite rather long history there still remain unsolved problems related to complete description of nonstationary transition to self-sustaining combustion, correct determination of the ignition moment, determination of the EM high-temperature reaction kinetics, etc. In the early studies, the limiting cases of the EM ignition solely due to exothermic reactions either in the condensed or gas phase were investigated but later it was revealed that formany EMs such reactions can proceed simultaneously in both phases. This implies the necessity of analyzing the ignition mechanisms involving reactions in the condensed as well as in the gas phase. In this chapter, the attention is paid to theoretical description of transient burning rate behavior of the EMs exothermically reacting in both phases, to the formulation of ignition criterion and to the experimental methods of measuring transient burning rate. In addition, the problems of correct determination of the EMs high-temperature kinetics are discussed as well as the problems of ignition of EMs with shielded reacting surface (opaque and semitransparent substances). Obviously, due to restricted volume, the chapter could not answer all questions but its content may become useful for researchers working in this field in order to better understand state of the art of EMs ignition studies and better plan some future researches in this direction