Seasonal variations of basal cortisol and high stress response to captivity in Octodon degus, a mammalian model species.

Across vertebrates, the hypothalamic-pituitary-adrenal axis is a conserved neuroendocrine network that responds to changing environments and involves the release of glucocorticoids into the blood. Few studies have been carried out concerning mammalian adrenal regulation in wild species either in the laboratory or field, and even fewer have been able to determine true glucocorticoid baselines. We studied the South-American caviomorph rodent Octodon degus, a diurnal and social mammal that has become an important species in the biological research. First, we determined the plasma cortisol baseline and the acute stress concentrations during the non-reproductive and mating seasons in free-living individuals. Second, using the same protocol we assessed the impact of long-term captivity on the adrenal function in wild-caught degus and degus born in laboratory. Third, we examined laboratory groups formed with degus taken from two distant natural populations; one of them originally occurs at the Andes Mountains in high altitude conditions. The data revealed seasonal modulation of basal cortisol in the wild associated with mating. In laboratory, degus presented higher cortisol stress responses, with greater magnitudes shown in degus born and reared in captivity. No differences between populations were found. The results suggest differential regulatory mechanisms between basal and stress-induced cortisol levels, and context dependence of cortisol modulation in a mammalian species.

Ecological drivers of group living in two populations of the communally rearing rodent, Octodon degus.

Intraspecific variation in sociality is thought to reflect a trade-off between current fitness benefits and costs that emerge from individuals' decision to join or leave groups. Since those benefits and costs may be influenced by ecological conditions, ecological variation remains a major, ultimate cause of intraspecific variation in sociality. Intraspecific comparisons of mammalian sociality across populations facing different environmental conditions have not provided a consistent relationship between ecological variation and group-living. Thus, we studied two populations of the communally rearing rodent Octodon degus to determine how co-variation between sociality and ecology supports alternative ecological causes of group living. In particular, we examined how variables linked to predation risk, thermal conditions, burrowing costs, and food availability predicted temporal and population variation in sociality. Our study revealed population and temporal variation in total group size and group composition that covaried with population and yearly differences in ecology. In particular, predation risk and burrowing costs are supported as drivers of this social variation in degus. Thermal differences, food quantity and quality were not significant predictors of social group size. In contrast to between populations, social variation within populations was largely uncoupled from ecological differences.

Falta de vinculación de la prestación de los servicios de aseo urbano al sistema de regulación sectorial (SIRESE)

El Sistema de Regulación Sectorial (SIRESE) por su naturaleza y características, es un modelo que se beneficia de las ventajas de las principales corrientes regulatorias unisectoriales y multisectoriales, acorde con los requerimientos del país. El SIRESE, más que un conjunto de entidades sectoriales, es un sistema dinámico e interactivo, que intercambia prácticas y esperiencia, protegiendo los intereses de los usuarios, de las empresas prestatarias de los servicios y del estado, en estricto cumplimiento de la ley

Servicios de voz/Ip aplicado a la empresa petrolera Chaco S.A.

Se plantea una propuesta práctica de un sistema para la introducción de la tecnología de voz sobre IP en las redes de datos de la Empresa Petrolera Chaco S.A.Considerando la tecnología que esta posee en la parte de comunicacion.