98 resultados para Natural Bleaching Event

em RUN (Reposit


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Desertification is a critical issue for Mediterranean drylands. Climate change is expected to aggravate its extension and severity by reinforcing the biophysical driving forces behind desertification processes: hydrology, vegetation cover and soil erosion. The main objective of this thesis is to assess the vulnerability of Mediterranean watersheds to climate change, by estimating impacts on desertification drivers and the watersheds’ resilience to them. To achieve this objective, a modeling framework capable of analyzing the processes linking climate and the main drivers is developed. The framework couples different models adapted to different spatial and temporal scales. A new model for the event scale is developed, the MEFIDIS model, with a focus on the particular processes governing Mediterranean watersheds. Model results are compared with desertification thresholds to estimate resilience. This methodology is applied to two contrasting study areas: the Guadiana and the Tejo, which currently present a semi-arid and humid climate. The main conclusions taken from this work can be summarized as follows: • hydrological processes show a high sensitivity to climate change, leading to a significant decrease in runoff and an increase in temporal variability; • vegetation processes appear to be less sensitive, with negative impacts for agricultural species and forests, and positive impacts for Mediterranean species; • changes to soil erosion processes appear to depend on the balance between changes to surface runoff and vegetation cover, itself governed by relationship between changes to temperature and rainfall; • as the magnitude of changes to climate increases, desertification thresholds are surpassed in a sequential way, starting with the watersheds’ ability to sustain current water demands and followed by the vegetation support capacity; • the most important thresholds appear to be a temperature increase of +3.5 to +4.5 ºC and a rainfall decrease of -10 to -20 %; • rainfall changes beyond this threshold could lead to severe water stress occurring even if current water uses are moderated, with droughts occurring in 1 out of 4 years; • temperature changes beyond this threshold could lead to a decrease in agricultural yield accompanied by an increase in soil erosion for croplands; • combined changes of temperature and rainfall beyond the thresholds could shift both systems towards a more arid state, leading to severe water stresses and significant changes to the support capacity for current agriculture and natural vegetation in both study areas.

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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia do Ambiente,perfil Gestão e Sistemas Ambientais

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Dissertação apresentada para obtenção do Grau de Doutor em Biologia (especialidade Microbiologia), pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de mestre em: Ordenamento do Território e Planeamento Ambiental

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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 do Ambiente, perfil Gestão e Sistemas Ambientais

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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia do Ambiente, perfil Gestão e Sistemas Ambientais.

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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção de Grau de Mestre em Engenharia do Ambiente, perfil Gestão e Sistemas Ambientais

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Perifèria. Revista de recerca i formació en antropologia, N.10

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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 Mecânica

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Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Ciência e Sistemas de Informação Geográfica

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

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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 do Ambiente, perfil de Engenharia Ecológica

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Photo-interpretation of aerial stereopairs of the Sintra region on the approx. 1/32 000 scale together with field work allowed the production of the present Tectonic Map of the Sintra region. It is now possible to separate structures which resulted from two different tectonic events: one, corresponding to the intrusion of the Late Cretaceous Sintra igneous diapir, and the other the Miocene compressive event, the most important tectonic inversion phase of the Lusitanian Basin. The former are present to the south, southeast and east of the intrusion and within the intrusion itself, affecting the peripheral granites and their contacts with the gabbro-syenite core. These structures comprehend: i) faults and conical fractures striking parallel to the massif boundary, which were intruded by dykes, ii) vertical faults and fractures of two conjugate sets, dextral NNW-SSE and sinistral NNE-SSW. These faults are certainly associated with the E-W striking massif's northwards directed thrust and indicate a N-S oriented horizontal maximum compressive stress. The Miocene compressive event reactivated most of the inherited structures as follows. The NNWSSE faults located on the Sintra southern platform were reactivated as dextral strike slip faults and the E-W thrust along the northern boundary of the massif was also reactivated. This thrust propagated to the east. It also enhanced the asymmetry of the rim-syncline, uplifted the massif and reactivated the NNE-SSW faults as sinistral lateral ramps, which also accommodated vertical throw. The present Tectonic Map of Sintra together with the available geophysical data (MOREIRA, 1984, KULLBERG et al., 1991, SILVA & MIRANDA, 1994) allowed reassessment of the models proposed for the emplacement of the Sintra, Sines and Monchique igneous massifs, which intruded during Late Cretaceous times along the deep dextral NNW-SSE oriented strike slip fault (RIBEIRO et al., 1979; TERRINHA, 1998; TERRINHA & KULLBERG, 1998).

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The S100 proteins are 10-12 kDa EF-hand proteins that act as central regulators in a multitude of cellular processes including cell survival, proliferation, differentiation and motility. Consequently, many S100 proteins are implicated and display marked changes in their expression levels in many types of cancer, neurodegenerative disorders, inflammatory and autoimmune diseases. The structure and function of S100 proteins are modulated by metal ions via Ca2+ binding through EF-hand motifs and binding of Zn2+ and Cu2+ at additional sites, usually at the homodimer interfaces. Ca2+ binding modulates S100 conformational opening and thus promotes and affects the interaction with p53, the receptor for advanced glycation endproducts and Toll-like receptor 4, among many others. Structural plasticity also occurs at the quaternary level, where several S100 proteins self-assemble into multiple oligomeric states, many being functionally relevant. Recently, we have found that the S100A8/A9 proteins are involved in amyloidogenic processes in corpora amylacea of prostate cancer patients, and undergo metal-mediated amyloid oligomerization and fibrillation in vitro. Here we review the unique chemical and structural properties of S100 proteins that underlie the conformational changes resulting in their oligomerization upon metal ion binding and ultimately in functional control. The possibility that S100 proteins have intrinsic amyloid-forming capacity is also addressed, as well as the hypothesis that amyloid self-assemblies may, under particular physiological conditions, affect the S100 functions within the cellular milieu.