Updated Nucleosynthesis Constraints on Unstable Relic Particles

We revisit the upper limits on the abundance of unstable massive relic particles provided by the success of Big-Bang Nucleosynthesis calculations. We use the cosmic microwave background data to constrain the baryon-to-photon ratio, and incorporate an extensively updated compilation of cross sections into a new calculation of the network of reactions induced by electromagnetic showers that create and destroy the light elements deuterium, he3, he4, li6 and li7. We derive analytic approximations that complement and check the full numerical calculations. Considerations of the abundances of he4 and li6 exclude exceptional regions of parameter space that would otherwise have been permitted by deuterium alone. We illustrate our results by applying them to massive gravitinos. If they weigh ~100 GeV, their primordial abundance should have been below about 10^{-13} of the total entropy. This would imply an upper limit on the reheating temperature of a few times 10^7 GeV, which could be a potential difficulty for some models of inflation. We discuss possible ways of evading this problem.Comment: 40 pages LaTeX, 18 eps figure

Utilização do bagaço de cana-de-açúcar em dietas com elevada proporção de concentrados para novilhos Nelore em confinamento Levels of sugarcane bagasse in diets with high concentrate for Nellore steers in feedlot

O objetivo deste trabalho foi avaliar o desempenho e características de carcaça de bovinos submetidos a dietas de alto concentrado contendo 15, 21 ou 27% da matéria seca em bagaço de cana-de-açúcar. Foram utilizados 24 novilhos Nelore, com peso médio em jejum de 279 kg e 24 meses de idade, confinados por um período de 98 dias. Não foram observados efeitos significativos para as características de ganho médio diário (média =1,461 kg) e eficiência alimentar. Foi observado efeito linear entre matéria seca ingerida e níveis de bagaço, com maior consumo nos tratamentos com menor percentagem de bagaço. Consistente com o comportamento do consumo, o peso do fígado também apresentou efeito linear, em função dos níveis de bagaço, sendo maior nos tratamentos com maior proporção de concentrado. As características peso de carcaça quente, gordura renal e pélvica, área de olho de lombo e espessura de gordura subcutânea não diferiram entre os tratamentos. Entretanto, observou-se comportamento linear do rendimento de carcaça, em função dos níveis de bagaço, sendo maior nos tratamentos com maior proporção de concentrado, consistente com o nível energético da ração. Os resultados indicam a viabilidade do uso de 15 ou 21% de bagaço como único volumoso, em dietas com elevada proporção de concentrado contendo milho, polpa de citrus e farelo de soja para novilhos Nelore em confinamento.<br>The objective of this work was to evaluate the performance and carcass characteristics of cattle fed high concentrate diets containing 15, 21 or 27% of sugarcane bagasse in the dry matter. Twenty-four Nellore steers with 279 kg of shrunk body weight and 24 months of age, two per pen, were fed for 98 days. No significant effects were observed for average daily gain (mean =1.461 kg) and feed efficiency among the treatments. It was observed a linear effect between dry matter intake and levels of bagasse, with greater intake in treatments with lower proportion of bagasse. Consistent with intake, the liver weight presented linear association with bagasse levels, with higher weight in treatments with more concentrate. The hot carcass weight, kidney, pelvic, heart and inguinal fat, ribeye area and fat thickness were no different between treatments. However, it was observed a linear association between dressing percentage and bagasse levels, with higher percentage in treatments with more concentrate, consistent with the energy level of the diet. The results showed the viability of the use of 15 or 21% of sugarcane bagasse as the only roughage in high concentrate diets with corn, citrus pulp and soybean meal for Nellore steers in feedlot