Behavior of a bipartite system in a cavity

We study the time evolution of a superposition of product states of two dressed atoms in a spherical cavity in the situations of an arbitrarily large cavity (free space) and of a small one. In the large-cavity case, the system dissipates, whereas, for the small cavity, the system evolves in an oscillating way and never completely decays. We verify that the von Neumann entropy for such a system does not depend on time, nor on the size of the cavityComment: 9 pages 2 figures, Revtex, Version accepted to be published in Physical Review

Exact solution for the energy density inside a one-dimensional non-static cavity with an arbitrary initial field state

We study the exact solution for the energy density of a real massless scalar field in a two-dimensional spacetime, inside a non-static cavity with an arbitrary initial field state, taking into account the Neumann and Dirichlet boundary conditions. This work generalizes the exact solution proposed by Cole and Schieve in the context of the Dirichlet boundary condition and vacuum as the initial state. We investigate diagonal states, examining the vacuum and thermal field as particular cases. We also study non-diagonal initial field states, taking as examples the coherent and Schrodinger cat states.Comment: 10 pages, 8 figure

Conhecimentos maternos sobre amamentação entre puérperas inscritas em programa de pré-natal Breastfeeding knowledge among post-partum women previously enrolled in a prenatal program

O objetivo deste estudo foi conhecer o nível de informação sobre amamentação entre as mulheres que participam do programa de pré-natal na Maternidade-Escola da Universidade Federal do Rio de Janeiro. A amostra totalizou 135 puérperas que responderam a questionário estruturado, contendo perguntas objetivas sobre aspectos práticos e teóricos do aleitamento materno. Os resultados mostraram que as mulheres iniciaram o pré-natal, em média, com 16 semanas de gravidez e realizaram cerca de oito consultas. Dentre elas, 53,3% afirmaram ter recebido informações sobre aleitamento materno durante o acompanhamento pré-natal e a informação mais lembrada por 22,2% foi a de amamentar até os seis meses de vida do bebê. Quanto ao momento ideal para a primeira mamada, 50,4% consideraram ser logo após o parto e 47,4% apontaram o leite materno como benéfico para proteger o bebê contra doenças. Embora as mães tenham conhecimentos básicos sobre aleitamento materno, questões como o momento ideal para a primeira mamada, a importância do colostro e aspectos nutricionais relacionados à nutriz ainda precisam ser melhor esclarecidos durante o pré-natal e no período pós-parto imediato.<br>The purpose of this study was to evaluate knowledge of breastfeeding issues among post-partum women who had participated in a prenatal program at the Rio de Janeiro Federal University (UFRJ) Maternity Teaching Hospital. The sample totaled 135 post-partum women who answered a structured questionnaire with objective questions about practical and theoretical aspects of breastfeeding. The women had begun prenatal care at the 16th week of gestation on average, with an average of 8 medical consultations. Some 53.3% stated having received information about breastfeeding during prenatal care, and 22.2% stated that the information they remembered the best was that they should breastfeed for the first 6 months. Regarding the best moment for the first feeding, 50.4% identified it as immediately after delivery. Some 47.4% said breastfeeding protects the child from diseases. Thus, although the mothers demonstrated basic knowledge about breastfeeding, issues like the best moment for the first feeding, the importance of colostrum, and nutritional aspects for nursing mothers require further clarification during prenatal care and the immediate post-partum period