704 resultados para B13
Resumo:
Tesis (Maestro en Ciencias con especialidad en Inmunobiología) U. A. N. L., Facultad de Ciencias Biológicas, 2008.
Resumo:
Trasparenze presentate a lezione. Si consiglia agli studenti di stamparne una copia prima della lezione e di portarla con sé onde riportare su di essa ulteriori annotazioni.
Resumo:
The Filchner-Ronne ice shelf, which drains most of the marine-based portions of the West Antarctic ice sheet, is the largest ice shelf on Earth by volume. The origin and properties of the ice that constitutes this shelf are poorly understood, because a strong reflecting interface within the ice and the diffuse nature of the ice?ocean interface make seismic and radio echo sounding data difficult to interpret. Ice in the upper part of the shelf is of meteoric origin, but it has been proposed that a basal layer of saline ice accumulates from below. Here we present the results of an analysis of the physical and chemical characteristics of an ice core drilled almost to the bottom of the Ronne ice shelf. We observe a change in ice properties at about 150 m depth, which we ascribe to a change from meteoric ice to basal marine ice. The basal ice is very different from sea ice formed at the ocean surface and we propose a formation mechanism in which ice platelets in the water column accrete to the bottom of the ice shelf.