228 research outputs found
Consistency of the mass variation formula for black holes accreting cosmological fluids
We address the spherical accretion of generic fluids onto black holes. We
show that, if the black hole metric satisfies certain conditions, in the
presence of a test fluid it is possible to derive a fully relativistic
prescription for the black hole mass variation. Although the resulting equation
may seem obvious due to a form of it appearing as a step in the derivation of
the Schwarzschild metric, this geometrical argument is necessary to fix the
added degree of freedom one gets for allowing the mass to vary with time. This
result has applications on cosmological accretion models and provides a
derivation from first principles to serve as a base to the accretion equations
already in use in the literature.Comment: 4 pages, 1 figure. To appear in Gen. Rel. Gra
Produção de mudas do tipo rebentão, utilizando coroas de três cultivares de abacaxi inoculadas com fungos micorrízicos
GEANT4 : a simulation toolkit
Abstract Geant4 is a toolkit for simulating the passage of particles through matter. It includes a complete range of functionality including tracking, geometry, physics models and hits. The physics processes offered cover a comprehensive range, including electromagnetic, hadronic and optical processes, a large set of long-lived particles, materials and elements, over a wide energy range starting, in some cases, from 250 eV and extending in others to the TeV energy range. It has been designed and constructed to expose the physics models utilised, to handle complex geometries, and to enable its easy adaptation for optimal use in different sets of applications. The toolkit is the result of a worldwide collaboration of physicists and software engineers. It has been created exploiting software engineering and object-oriented technology and implemented in the C++ programming language. It has been used in applications in particle physics, nuclear physics, accelerator design, space engineering and medical physics. PACS: 07.05.Tp; 13; 2
Prevalence and risk factors for bovine leptospirosis in Mato Grosso do Sul, Brazil
Foi investigada a prevalência de anticorpos antileptospira em fêmeas bovinas com idade igual ou superior a 24 meses, provenientes de 178 rebanhos de 22 municípios do estado de Mato Grosso do Sul, bem como identificados fatores de risco associados à infecção. Foram analisadas 2.573 amostras de soro sangüíneo por meio do teste de soroaglutinação microscópica perante 10 sorovares de leptospira. Títulos iguais ou superiores a 100 para um ou mais sorovares foram detectados em 1.801 fêmeas (98,8%) de 161 (96,5%) rebanhos. O sorovar Hardjo (65,6%) foi apontado como o mais provável, seguido do sorovar Wolffi (12,3%). Os resultados demonstram que a leptospirose bovina se encontra presente em todos os municípios estudados, com alta prevalência, tanto em animais como em rebanhos. Os fatores de risco identificados neste estudo e associados à infecção por bactérias do gênero lepstopira foram o tipo de exploração pecuária de corte e a raça Zebu. _____________________________________________________________________________________________________________ ABSTRACTThe prevalence of anti-Leptospira spp. antibodies was estimated for female cattle aged 24 months or older. The sample comprised 178 herds from 22 counties in the state of Mato Grosso do Sul, Brazil. The risk factors associated with the presence of infeccion were investigated. A total of 2,573 blood serum samples were tested against 10 leptospira serovars using the microagglutination test (MAT). Titers of 100 or higher for one or more serovars were detected in 1,801 females (98.8%) from 161 herds (96.5%). Serovar Hardjo (65.6%) was the most frequent, followed by serovar Wolffi (12.3%). These results suggest that bovine leptospirosis is widespread in all the counties under study, with a high prevalence both at the animal and the herd level. Beef farms and the Zebu breed were associated to the higher risk of herd infection by leptospiras
Efetividade de rizóbios e caracterização fenotípica dos isolados que nodulam feijão-caupi em solos da Amazônia Central
Effects of weaning age and weight on lamb growth rate of Morada Nova breed raised in a tropical extensive production system
Estimativa de ocorrência de precipitação em áreas agrícolas utilizando floresta de caminhos ótimos
Interação de bactérias fluorescentes do gênero Pseudomonas e de Bacillus spp. com a rizosfera de diferentes plantas
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