806 resultados para Irvin, Dale T


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The circum-Antarctic Southern Ocean is an important region for global marine food webs and carbon cycling because of sea-ice formation and its unique plankton ecosystem. However, the mechanisms underlying the installation of this distinct ecosystem and the geological timing of its development remain unknown. Here, we show, on the basis of fossil marine dinoflagellate cyst records, that a major restructuring of the Southern Ocean plankton ecosystem occurred abruptly and concomitant with the first major Antarctic glaciation in the earliest Oligocene (~33.6 million years ago). This turnover marks a regime shift in zooplankton-phytoplankton interactions and community structure, which indicates the appearance of eutrophic and seasonally productive environments on the Antarctic margin. We conclude that earliest Oligocene cooling, ice-sheet expansion, and subsequent sea-ice formation were important drivers of biotic evolution in the Southern Ocean.

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Las mujeres que buscan servicios de urgencia por complicaciones de un aborto (hemorragia, infección y lesiones del tracto reproductivo) deberían ser un grupo prioritario para los programas de salud reproductiva. Frecuentemente, estas mujeres reciben atención de mala calidad que no cubre sus múltiples necesidades de salud. En ocasiones se les da de alta sin haber recibido consejería en recuperación postoperatoria, planificación familiar y otros aspectos de salud reproductiva

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In this study, I examine the agon scene in Euripides' Alcestis. The agon is placed in the 4th episode, when Alcestis' corpse has recieved all preparations for the funeral, and Admeto has already accomodated Heracles in the palace, without telling him, however, about the last occurrences. This episode is the biggest of the play with 360 verses, what could cause the prolongation of the action and consequently the decline of the emotional tonus. Nevertheless, Euripides has composed this episode with very diversified elements, that it could be divided in scenes, what confers certain agitily to the events succession that accelerates the end of the play. I took as basis the commentaries by A. M. Dale and by L P. E. Parker, and whenever necessary, I have also recurred to the James Diggle?s and D. J Conacher?s editions. Another important text for the present discussion of the agon in Alcestis is the book by Michael Lloyd, The Agon in Euripides