Spontaneous emission of an atom near a wedge

It is a well known fact that non-trivial boundary conditions affect the interaction between atoms and the always present quantized electromagnetic field. In this paper, we focus on how the spontaneous emission rate of a given excited atom is altered when placed inside a perfectly conducting wedge. We begin by briefly presenting the formalism on which our calculations are founded, proceeding then to a long but straightforward calculation of the transition rate. We present results for a general atom but, for the sake of simplicity, we narrow them down to an effective two-level system in our numerical investigations. From these we conclude that the results are physically sound.Comment: 10 pages, version replaced to match the published on

Fatores de risco associados à qualidade microbiológica do leite de rebanhos fornecedores de agroindústrias familiares.

Dentre os parâmetros que caracterizam a qualidade do leite, o atendimento ao limite definido na legislação para contagem bacteriana se caracteriza por um desafio à cadeia produtiva de Rondônia. O objetivo do trabalho foi identificar os fatores de risco associados à contagem bacteriana do leite de rebanhos fornecedores de agroindústrias familiares do estado

Prevalência e fatores de risco associados à mastite subclínica em rebanhos fornecedores de agroindústrias familiares de Rondônia.

A contagem de células somáticas (CCS) é o indicador geral da saúde do úbere e é utilizada como indicador universal da qualidade do leite. Embora vários fatores possam estar associados à variação na CCS, a ocorrência de mastite é considerada o principal fator, sendo o limite de 200.000 células/ml o mais indicado para estimar uma nova infecção intramamária. O objetivo do trabalho foi estimar a prevalência e os fatores de risco associados à mastite subclínica em rebanhos fornecedores de agroindústrias familiares com serviço de inspeção do estado de Rondônia

Radiação fotossinteticamente ativa incidente e Refletida acima e abaixo do dossel de floresta de Mata Atlântica em Coruripe, Alagoas

The study of solar radiation is important to understand the several physical, chemical and biological processes that occur in the biosphere, particularly in the forest. The objective of this study has been to evaluate the temporal evolution of incident and reflected Photosynthetic Active Radiation (PAR) above and below the canopy of the Mata Atlantica forest. The study has been conducted in a Private Reserve Natural Heritage, located in the Coruripe city, Alagoas, during the period from October 2009 to September 2010, based on the PAR (2, 13, 26 m) observations obtained at the micrometeorological station, installed on a 24 meters high tower (10° 17' 36"S, 36° 17' 24"W, 160 m asl). According to the results the incident and reflected PAR outside (PAR↓_Ext and PAR↑_Ext) and inside (PAR↑_Spf) forest follow the seasonality imposed by the apparent motion of the Sun. The higher PAR values occur during the dry season, exceeding 600 and 12 W m-2, and during the wet season these averages was less than 300 and 8.0 W m-2, influenced by cloudiness. At the beginning and ending of sunlight time PAR↑_Spf values near zero were measured. The opposite measurements of about 14 W m-2, around 12 h (November and December) were observed