15 resultados para Decay and Disaster


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Dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geospatial Technologies.

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Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.

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Aging is a long-standing biological question of tremendous social and cultural importance. Despite this, only in the last 15 years has biology started to make significant progress in understanding the underlying mechanisms that regulate aging. This progress stemmed mainly from the use of model organisms, which allowed the discovery of several genes directly modulating longevity. Interestingly, several of these longevity genes are necessary for normal mitochondrial function, and disruption of their activity delays the aging process. This is somewhat paradoxical, considering the importance of cellular respiration for energy production and viability of eukaryotic organisms. One possible rationalization for this is that by decreasing cellular respiration, reactive oxygen species (ROS) generation is also reduced, and in that way, cellular decay and aging are delayed.(...)

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A presente dissertação é circunscrita no espaço e no tempo, tendo como objecto de estudo fundamental o concelho de Setúbal durante a I Guerra Mundial (1914-1918). Enquadrando historicamente os impactos do conflito no contexto nacional, Setúbal é revisitada entre os finais de oitocentos e os primórdios do século XX a fim de retratar política, económica, social e culturalmente um dos maiores centros urbanos portugueses dos finais da Monarquia Constitucional e do início da I República. Numa lógica de impactos políticos e económico-sociais, esta investigação promove o redescobrir das vivências quotidianas de Setúbal durante um dos períodos mais negros da História da Humanidade. Através do estudo dos mecanismos de acção e intervenção municipais, bem como dos resultados eleitorais e dinâmicas políticopartidárias locais, transmite-se como foram vividos acontecimentos marcantes da vida pública de Portugal, nomeadamente o 14 de Maio de 1915 e o coup d’état sidonista, realçando como dimensões operárias anárquicas e sindicalistas conviviam com grupos conservadores, católicos e monárquicos. Num plano de economia de guerra, o mundo agrícola é abordado em diferentes sectores, nomeadamente na laranja, na cortiça e nos vinhos, dando maior atenção às questões relacionadas com a decadência da fruta e à abertura de novos mercados exportadores, como o Brasil, pela Casa José Maria da Fonseca. A indústria de conservas de peixe, que viveu um boom neste período como resultado da intensa procura externa dos países aliados que tinham nas latas de conserva o alimento das tropas nas trincheiras, representa outro foco de análise deste trabalho. Consequentemente aborda-se o papel da estrutura portuária local na resposta às necessidades de consumo britânicas, francesas e italianas. Por fim, os impactos sociais do conflito em Setúbal constituem um dos enunciados desta investigação, compreendendo como o estudo de uma imprensa dividida na questão intervencionismo versus anti-intervencionismo reflectiu um concelho que viveu como poucos a crise de abastecimentos e a carestia de vida. A proliferação de greves, manifestações contra a guerra, as deserções militares e os assaltos colectivos representam o culminar de um vulcão que entrou em erupção e que ainda sofreu as agruras da epidemia da gripe pneumónica até ao final do ano de 1918.

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The most important processes for the creation of S12+ to S14+ ions excited states from the ground configurations of S9+ to S14+ ions in an electron cyclotron resonance ion source, leading to the emission of K X-ray lines, are studied. Theoretical values for inner-shell excitation and ionization cross sections, including double KL and triple KLL ionization, transition probabilities and energies for the deexcitation processes, are calculated in the framework of the multi-configuration Dirac-Fock method. With reasonable assumptions about the electron energy distribution, a theoretical K$\alpha$ X-ray spectrum is obtained, which is compared to recent experimental data.

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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Informática

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Old timber structures may show significant variation in the cross section geometry along the same element, as a result of both construction methods and deterioration. As consequence, the definition of the geometric parameters in situ may be both time consuming and costly. This work presents the results of inspections carried out in different timber structures. Based on the obtained results, different simplified geometric models are proposed in order to efficiently model the geometry variations found. Probabilistic modelling techniques are also used to define safety parameters of existing timber structures, when subjected to dead and live loads, namely self-weight and wind actions. The parameters of the models have been defined as probabilistic variables, and safety of a selected case study was assessed using the Monte Carlo simulation technique. Assuming a target reliability index, a model was defined for both the residual cross section and the time dependent deterioration evolution. As a consequence, it was possible to compute probabilities of failure and reliability indices, as well as, time evolution deterioration curves for this structure. The results obtained provide a proposal for definition of the cross section geometric parameters of existing timber structures with different levels of decay, using a simplified probabilistic geometry model and considering a remaining capacity factor for the decayed areas. This model can be used for assessing the safety of the structure at present and for predicting future performance.

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Assessing the safety of existing timber structures is of paramount importance for taking reliable decisions on repair actions and their extent. The results obtained through semi-probabilistic methods are unrealistic, as the partial safety factors present in codes are calibrated considering the uncertainty present in new structures. In order to overcome these limitations, and also to include the effects of decay in the safety analysis, probabilistic methods, based on Monte-Carlo simulation are applied here to assess the safety of existing timber structures. In particular, the impact of decay on structural safety is analyzed and discussed, using a simple structural model, similar to that used for current semi-probabilistic analysis.

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Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.

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Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.

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Dissertation presented to obtain the Ph.D degree in Biology

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Dissertation presented to obtain the Ph.D degree in Biology

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Dissertation presented to obtain the Ph.D degree in Biology

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Dissertation presented to obtain the Master Degree in Molecular, Genetics and Biomedicine

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Cell division is a highly dynamic process where sister chromatids remain associated with each other from the moment of DNA replication until the later stages of mitosis, giving rise to two daughter cells with equal genomes. The “molecular glue” that links sister DNA molecules is called cohesin, a tripartite ring-like protein complex composed of two Structural Maintenance of Chromosome proteins (Smc1 and Smc3) bridged by a kleisin subunit Rad21/Scc1, that together prevent precocious sister chromatid separation. Accumulating evidence has suggested that cohesion decay may be the cause of segregation errors that underlie certain human pathologies. However it remains to be determined how much cohesin loss abolishes functional sister chromatid cohesion. To answer these questions, we have developed different experimental conditions aiming to titrate the levels of cohesin on mitotic chromosomes in a precise manner. Using these tools, we will determine the minimal amount of cohesin needed to confer functional cohesion. The approaches described here take advantage of a system in Drosophila melanogaster where the Tobacco Etch Virus (TEV) protease can cleave the Rad21 subunit of cohesin leading to precocious sister chromatid separation. Firstly, we tried to express different levels of TEV protease to obtain partial loss of cohesion. However, this approach has failed to produce systematic different levels of sister chromatid separation. Most of the work was therefore focused on a second strategy, for which we established strains with different levels of cohesin sensitive/cohesin resistant to TEV protease. Strains containing different amounts of functional cohesin (TEV resistant) were tested by in vitro cleavage and by in vivo injections in embryos for their ability to promote sister chromatid cohesion. Our results reveal that removal of half of the cohesin complexes does not impair chromosome segregation, implying that chromosome cohesion is less sensitive to cohesin amounts than previously anticipated.