942 resultados para genesis


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The emergence of soft-bodied metazoans and the radiation of the earliest skeletal organisms substantially changed the ecological dynamics of Ediacaran environments, leading to the genesis of biogenic hard-part deposits for the fi rst time in Earth's history. The impact of bioclast origin on sedimentary processes is analyzed herein, focusing on the sedimentology and taphonomy of shell concentrations dominated by the Ediacaran index fossil Cloudina from the Itapucumí Group, Paraguay. Skeletal concentrations include both dense accumulations of parautochthonous, disarticulated specimens (Type 1 deposits) and in situ specimens preserved as loosely packed assemblages (Type 2 deposits). At that time, Cloudina was the critical source of durable biomineralized hard parts in an environment nearly free of other bioclasts. The simple fabric and geometry of these accumulations are typical of Cambrian-style shell beds. Despite their Precambrian age, these deposits indicate that the establishment of the Phanerozoic style of marine substrates and preservation in early shell beds was determined more by the acquisition of hard parts than by environmental changes. © 2013 Geological Society of America.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Impacts on the environment and soil biological activity result in changes in the processes of formation of biogenic and fisiogenic aggregates. Aiming to evaluate the influence on physical and biological genesis of aggregates of Cerrado soils and determine the main environmental factors that determine the characteristics of households in the area of production under integrated crop-livestock (ICL), was developed this study in Farm Cabeceira, Maracaju-MS, in areas of ICL. The areas evaluated were: Savana, pasture/maize, corn/cotton and cotton/soybeans being evaluated during the dry (May/2009) and rainy (March 2010) season. To identify the pathways of aggregation were used morphological patterns, and established three clusters: fisiogenic, biogenic and intermediates. The aggregates were analyzed for exchangeable cations, carbon and aggregate stability, soil was analyzed for the exchangeable cations, particle size fractionation of soil organic matter, oxidizable fractions of total organic carbon, particle size analysis and soil macrofauna. In all areas studied, in the dry season, the highest values were quantified aggregate intermediates, while in the rainy season, in general, no differences were observed aggregates formed by different routes in areas except cotton/soybeans. The aggregates showed positive correlation with biogenic carbon and were found in lesser amounts compared to fisiogenic and intermediates. The different types of aggregates formed, besides having different characteristics morphological also differ as to chemical characteristics.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conclusiones de la Reunion Latinoamericana Preparatoria de la Conferencia Mundial de Poblacion, San Jose, de la Conferencia Mundial sobre Poblacion (Bucarest, Agosto 1974) y de la 2a Reunion Latinoamericana sobre Poblacion (Mexico, Marzo 1975). En la reunion de San Jose se destaca la hegemonia del principio de la soberania nacional, la negativa a la fijacion de metas cuantitativas y la subordinacion de las politicas de poblacion a las politicas de desarrollo. En el Plan de Accion Mundial aprobado en Bucarest se destaca el rol de los factores estructurales en la genesis de los problemas demograficos, la importancia del establecimiento de un nuevo orden economico mundial y la armonia que debe existir entre las politicas de poblacion y las de desarrollo. La reunion de Mexico evalua los resultados de la Conferencia de Bucarest y discute sus implicancias para America Latina. Se adopta un marco etico-juridico para las politicas de poblacion y se dan recomendaciones sobre su formulacion, implementacion y evaluacion.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Educação Escolar - FCLAR

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA