16 research outputs found
Multiband model for penetration depth in MgB2
The results of first principles calculations of the electronic structure and
the electron-phonon interaction in MgB2 are used to study theoretically the
temperature dependence and anisotropy of the magnetic field penetration depth.
The effects of impurity scattering are essential for a proper description of
the experimental results. We compare our results with experimental data and we
argue that the two-band model describes the data rather well.Comment: submitted to Phys. Rev.
Comprehensive Skeletal Phenotyping and Linkage Mapping in an Intercross of Recombinant Congenic Mouse Strains HcB-8 and HcB-23
The toxicity of soil samples containing TNT and other ammunition derived compounds in the enchytraeid and collembola-biotest
Aeolian sand movement and relative sea-level rise in Ho Bugt, western Denmark, during the `Little Ice Age'
Alimentação e ecomorfologia de duas espécies de piranhas (Characiformes: Characidae) do lago de Viana, estado do Maranhão, Brasil Feeding and ecomorphology of two species of piranhas (Characiformes: Characidae) from the Viana Lake, Maranhão state, Brazil
Serrasalmus aff. brandtii e Pygocentrus nattereri sĂŁo duas espĂ©cies de piranhas comuns no Lago de Viana, um lago formado a partir das inundações do Rio PindarĂ©, tributário da margem esquerda do Rio Mearim. Uma amostra composta por 249 exemplares destas espĂ©cies foi estudada a fim de identificar a composição da dieta e as estratĂ©gias alimentares empregadas pelas duas. Os peixes foram coletados trimestralmente durante um ano, entre março de 1998 e março de 1999, usando redes de emalhar e tarrafas. A composição qualitativa da dieta foi analisada com uso do mĂ©todo de freqĂĽĂŞncia de ocorrĂŞncia. As estratĂ©gias alimentares empregadas pelas espĂ©cies foram inferidas atravĂ©s do mĂ©todo gráfico de Costello (1990), modificado por Amundsen et al. (1996). Os resultados indicaram que peixes foi o item encontrado com maior freqĂĽĂŞncia nos estĂ´magos de ambas as espĂ©cies, seguido de matĂ©ria vegetal, com maior participação na dieta de P. nattereri. Os recursos peixes e vegetais tenderam a apresentar relações inversas quando comparados com as diferentes classes de comprimento. A análise gráfica da dieta de P. nattereri e S. aff. brandtii sugere que a maioria dos indivĂduos utiliza vários recursos simultaneamente. Uma análise multivariada de Ăndices ecomorfolĂłgicos indicou que as espĂ©cies sĂŁo segregadas com relação Ă habilidade natatĂłria, posição ocupada na coluna d'água e tamanho relativo das presas.<br>Serrasalmus aff. brandtii and Pygocentrus nattereri are two species of piranhas, both common in the Viana Lake, which is formed by the flooding waters of the PindarĂ© River, a tributary of the left bank of the Mearim River. A sample composed of 249 specimens of these species was studied in order to identify diet composition and feeding strategies employed by the two species. The piranhas were captured thrimonthly, during one year from March 1998 to March 1999 using gill and fishing nets of different mesh sizes. The qualitative composition of the diet was analysed through the frequency of occurrence method. The feeding strategies employed by the piranhas were inferred using the graphic method of Costello (1990), modified by Amundsen et al. (1996). The results indicated that fish was the main food item in the stomach contents of the two species, followed by plant material, more in the P. nattereri. Fish and plant material showed different relationships in relation to piranhas's length classes. The graphic analysis of the feeding strategies employed by P. nattereri and S. aff. brandtii suggest a generalist habit, wide width niche with strong participation of the within-phenotype component, which indicated that the majority of individuals of these species use several resources simultaneously. A multivariate analysis of the ecomorphological index indicated that the species are discriminated by swimming ability, water column position and relative prey size