Role of the Coulomb and the vector-isovector ρ\rho potentials in the isospin asymmetry of nuclear pseudospin

We investigate the role of the Coulomb and the vector-isovector $\rho$ potentials in the asymmetry of the neutron and proton pseudospin splittings in nuclei. To this end, we solve the Dirac equation for the nucleons using central vector and scalar potentials with Woods-Saxon shape and $Z$ and $N-Z$ dependent Coulomb and $\rho$ potentials added to the vector potential. We study the effect of these potentials on the energy splittings of proton and neutron pseudospin partners along a Sn isotopic chain. We use an energy decomposition proposed in a previous work to assess the effect of a pseudospin-orbit potential on those splittings. We conclude that the effect of the Coulomb potential is quite small and the $\rho$ potential gives the main contribution to the observed isospin asymmetry of the pseudospin splittings. This isospin asymmetry results from a cancellation of the various energy terms and cannot be attributed only to the pseudospin-orbit term, confirming the dynamical character of this symmetry pointed out in previous works.Comment: 9 pages, 11 figures, uses revtex4; title was changed and several small corrections were made throughout the tex

Redução do nível de proteína bruta em rações para frangos de corte em ambiente de estresse por calor

Este estudo foi realizado para avaliar os efeitos da redução do nível de proteína bruta (PB) da ração com suplementação de aminoácidos sintéticos sobre o desempenho e o rendimento de carcaça de frangos de corte de 22 a 42 dias de idade mantidos sob estresse por calor. Utilizaram-se 280 frangos de corte machos da linhagem Cobb 500 com peso inicial de 856 ± 7,41 g, distribuídos em delineamentointeiramente casualizado, com cinco níveis de PB (21,6; 20,6; 19,6; 18,6 ou 17,6%), oito repetições e sete aves por unidade experimental. A temperatura no interior da sala foi mantida em 32,2 ± 0,6ºC, com umidade relativa de 66 ± 3,2% e temperatura de globo negro de 33,0 ± 0,7ºC. O índice de temperatura de globo e umidade (ITGU) calculado no período foi de 83 ± 0,9. Não houve efeito dos níveis de PB da ração sobre o ganho de peso, o consumo de ração e a conversão alimentar das aves. A redução dos níveis de PB da ração influenciou os pesos absolutos da carcaça e do peito, que foram maiores no nível de 19,6% de PB em relação ao de 21,6%. Entretanto, não houve efeito da redução dos níveis de PB sobre os pesos absolutos de coxa e de sobrecoxa nem sobre os rendimentos de peito, coxa e sobrecoxa. O nível de proteína bruta da ração, formulada utilizando-se o conceito de proteína ideal, pode ser reduzido de 21,6 até 17,6%, pois essa redução não prejudica as características de desempenho, nem o peso absoluto e o rendimento de cortes nobres de frangos de corte submetidos a estresse por calor.This study was performed to evaluate the effects of reduction of dietary crude protein level with supplementation of industrial amino acids on the performance and carcass yield of broilers between 22 to 42 days of age, under heat stress. It was used 280 Cobb broilers with initial weight of 856 ± 7.41 g, distributed in a complete randomized experimental design, with five crude protein levels (21.6; 20.6; 19.6; 18.6 and 17.6%), eight repetitions and seven broilers per experimental unit. The temperature inside the rooms was kept at 32.2 ± 0.6ºC, the relative humidity at 66 ± 3.2% and black globe temperature at 33.0 ± 0.7°C. The black globe-humidity index calculated for the period was 83 ± 0.9. There was no effect of crude protein levels on weight gain, feed intake and feed conversion of the birds. The reduction of dietary crude protein levels influenced the absolute weight of carcass and breast, and the level of 19.6% proportioned higher carcass and breast weights of the broilers compared to the level of 21.6% of crude protein. However, there was no effect of the reduction of levels of crude protein on absolute values of thigh and drumstick and also on breast, thigh and drumstick yields. The dietary crude protein level, formulated by using the ideal protein concept, can be reduced from 21.6 to 17.6% not negatively affecting the performance, absolute weight and noble cut yield of broilers under heat stress