Refugium for surface life on Snowball Earth in a nearly enclosed sea? A numerical solution for sea-glacier invation through a narrow strait

Abstract Where photosynthetic eukaryotic organisms survived during the Snowball Earth events of the Neoproterozoic remains unclear. Our previous research tested whether a narrow arm of the ocean, similar to the modern Red Sea, could have been a refugium for photosynthetic eukaryotes during the Snowball Earth. Using an analytical ice-flow model, we demonstrated that a limited range of climate conditions could restrict sea-glacier flow sufficiently to allow an arm of the sea to remain partially free from sea-glacier penetration, a necessary condition for it to act as a refugium. Here we expand on the previous study, using a numerical ice-flow model, with the ability to capture additional physics, to calculate sea-glacier penetration, and to explore the effect of a channel with a narrow entrance. The climatic conditions are made selfconsistent by linking sublimation rate to surface temperature. As expected, the narrow entrance allows parts of the nearly enclosed sea to remain safe from sea-glacier penetration for a wider range of climate conditions.

Análisis del concepto de liderazgo y sus aplicaciones en el contexto empresarial

El presente trabajo se realizó con el objetivo de tener una visión completa de las teorías del liderazgo, teniendo de este una concepción como proceso y poder examinar las diversas formas de aplicación en las organizaciones contemporáneas. El tema es enfocado desde la perspectiva organizacional, un mundo igualmente complejo, sin desconocer su importancia en otros ámbitos como la educación, la política o la dirección del estado. Su enfoque tiene que ver con el estudio académico del cual es la culminación y se enmarca dentro de la perspectiva constitucional de la Carta Política Colombiana que reconoce la importancia capital que tienen la actividad económica y la iniciativa privada en la constitución de empresas. Las diversas visiones del liderazgo han sido aplicadas de distintas maneras en las organizaciones contemporáneas y han generado diversos resultados. Hoy, no es posible pensar en una organización que no haya definido su forma de liderazgo y en consecuencia, confluyen en el campo empresarial multitud de teorías, sin que pueda afirmarse que una sola de ellas permita el manejo adecuado y el cumplimiento de los objetivos misionales. Por esta razón se ha llegado a concebir el liderazgo como una función compleja, en un mundo donde las organizaciones mismas se caracterizan no solo por la complejidad de sus acciones y de su conformación, sino también porque esta característica pertenece también al mundo de la globalización. Las organizaciones concebidas como máquinas que en sentido metafórico logran reconstituirse sus estructuras a medida que están en interacción con otras en el mundo globalizado. Adaptarse a las cambiantes circunstancias hace de las organizaciones conglomerados en permanente dinámica y evolución. En este ámbito puede decirse que el liderazgo es también complejo y que es el liderazgo transformacional el que más se acerca al sentido de la complejidad.

Elites e educação: itinerários escolares e percursos profissionais. Alentejo, séculos XIX e XX

A tese examina a relação entre as elites e a educação em Portugal durante a Monarquia Constitucional e na Iª República. Em primeiro lugar caracteriza o quadro europeu no qual emergiram os modernos sistemas de ensino, focando-se depois na análise dos processos de segmentação que separaram o ensino clássico do ensino técnico, passando em revista a literatura sobre o reformismo educativo português. Em segundo, analisa o processo de segmentação na cidade de Évora, capital de uma região caracterizada pela prática de uma agricultura essencialmente extensiva e comercial, na qual estavam implantadas as instituições de ensino que constituem o objeto de estudo: o Liceu e a Escola Industrial. Em terceiro, procede à caracterização dos espaços escolares; em quarto estuda as condutas públicas dos agentes educativos, em particular dos reitores e dos professores, colocando em destaque a sua intervenção pública; em quinto, caracteriza a procura a que foram sujeitos os vários institutos de ensino estudados: a ênfase foi colocada na mobilidade geográfica aferida a partir da naturalidade dos alunos e da residência dos pais; em sexto, foi efetuada a análise da extração social dos alunos e o perfil ocupacional dos pais. Finalmente, em último lugar, foram reconstituídos os percursos académicos e profissionais dos alunos liceais no arco cronológico antes enunciado; Elites and Education.School itineraries and career paths.Alentejo, 19th and 20th centuries. Abstract: The thesis examines the relation between elites and education in Portugal, during the Constitutional Monarchy and the First Republic. Firstly, it characterises the European context in which modern teaching systems emerged and it focuses on the analysis of the processes of segmentation that separate classic and technical teaching. It reviews literature on Portuguese educational reformism, centred on classic and technical teaching. Secondly, it analyses the process of segmentation in Évora, capital of a region that is characterised by agriculture, which is essentially extensive and commercial, home to the education institutions our study focuses on: the Liceu and the Industrial School. Thirdly, school facilities are characterised; then, public behaviour of educators, namely that of headmasters and teachers, highlighting their public intervention; it characterises the demand in these institutions - the emphasis is placed on geographic mobility, considering students' birthplace and their parents' residence; a study on students' backgrounds and parents' occupational profiles is carried out. Eventually, the academic and professional itineraries of Liceu students' are reconstituted, within the formerly described chronological arch.

Decomposition of organic matter in the presence of the herbicide clomazone.

Clomazone (2-(2-chlorophenyl) methyl-4.4-dimethyl-3-isoxazolidinone) is a post emergence herbicide widely used in rice fields in Rio Grande do Sul (Brazil) with high activity against Gramineae at the recommended application rate of 700 g/ha. The presence of this chemical in the water may affect microorganisms responsible for the decomposition of organic matter. Thus, a disturbe in the trophic chain sustained by the decompositors could happen. In the present work the decomposition rate of organic matter (Typha latifolia) exposed to several concentrations of a clomazone formulation: 0 (control), 25.0, 62.0, 156.0, 390.0 and 976.0mg/L on the basis of the active ingredient was evaluated. Five litter bags containing about 3.0g of pieces of T. latifolia leaves wereplaced in aquariums with 15 of reconstituted water. In cach aquarium were added 500g of sediment from the same place of the plant collection, as a source of decompositors microorganisms. The results relative tothe control, showed that the decomposition rate in the highest and lowest dose was reduced in 50.05 and 1,28%, respectively, after 80 days.