The influence of the conservation status and changes in the rainfall regime on forest-savanna mosaic dynamics in Northern Brazilian Amazonia

Coupled carbon/climate models are predicting changes in Amazon carbon and water cycles for the near future, with conversion of forest into savanna-like vegetation. However, empirical data to support these models are still scarce for Amazon. Facing this scenario, we investigated whether conservation status and changes in rainfall regime have influenced the forest-savanna mosaic over 20 years, from 1986 to 2006, in a transitional area in Northern Amazonia. By applying a spectral linear mixture model to a Landsat-5-TM time series, we identified protected savanna enclaves within a strictly protected nature reserve (Maracá Ecological Station - MES) and non-protected forest islands at its outskirts and compared their areas among 1986/1994/2006. The protected savanna enclaves decreased 26% in the 20-years period at an average rate of 0.131 ha year-1, with a greater reduction rate observed during times of higher precipitation, whereas the non-protected forest islands remained stable throughout the period of study, balancing the encroachment of forests into the savanna during humid periods and savannization during reduced rainfall periods. Thus, keeping favorable climate conditions, the MES conservation status would continue to favor the forest encroachment upon savanna, while the non-protected outskirt areas would remain resilient to disturbance regimes. However, if the increases in the frequency of dry periods predicted by climate models for this region are confirmed, future changes in extension and directions of forest limits will be affected, disrupting ecological services as carbon storage and the maintenance of local biodiversity.

Thin films composed of Ag nanoclusters dispersed in TiO2: Influence of composition and thermal annealing on the microstructure and physical responses

Noble metal powders containing gold and silver have been used for many centuries, providing different colours in the windows of the medieval cathedrals and in ancient Roman glasses. Nowadays, the interest in nanocomposite materials containing noble nanoparticles embedded in dielectric matrices is related with their potential use for a wide range of advanced technological applications. They have been proposed for environmental and biological sensing, tailoring colour of functional coatings, or for surface enhanced Raman spectroscopy. Most of these applications rely on the so-called localised surface plasmon resonance absorption, which is governed by the type of the noble metal nanoparticles, their distribution, size and shape and as well as of the dielectric characteristics of the host matrix. The aim of this work is to study the influence of the composition and thermal annealing on the morphological and structural changes of thin films composed of Ag metal clusters embedded in a dielectric TiO2 matrix. Since changes in size, shape and distribution of the clusters are fundamental parameters for tailoring the properties of plasmonic materials, a set of films with different Ag concentrations was prepared. The optical properties and the thermal behaviour of the films were correlated with the structural and morphological changes promoted by annealing. The films were deposited by DC magnetron sputtering and in order to promote the clustering of the Ag nanoparticles the as-deposited samples were subjected to an in-air annealing protocol. It was demonstrated that the clustering of metallic Ag affects the optical response spectrum and the thermal behaviour of the films.

The influence of nitrogen and oxygen additions on the thermal characteristics of aluminium-based thin films

The ternary aluminium oxynitride (AlNxOy) system offers the possibility to obtain a wide range of properties by tailoring the ratio between pure Al, AlNx and AlOy and therefore opening a significant number of possible applications. In this work the thermal behaviour of AlNxOy thin films was analysed by modulated infrared radiometry (MIRR), taking as reference the binary AlOy and AlNx systems. MIRR is a non-contact and non-destructive thermal wave measurement technique based on the excitation, propagation and detection of temperature oscillations of very small amplitudes. The intended change of the partial pressure of the reactive gas (N2 and/or O2) influenced the target condition and hence the deposition characteristics which, altogether, affected the composition and microstructure of the films. Based on the MIRR measurements and their qualitative and quantitative interpretation, some correlations between the thermal transport properties of the films and their chemical/physical properties have been found. Furthermore, the potential of such technique applied in this oxynitride system, which present a wide range of different physical responses, is also discussed. The experimental results obtained are consistent with those reported in previous works and show a high potential to fulfil the demands needed for the possible applications of the systems studied. They are clearly indicative of an adequate thermal response if this particular thin film system is aimed to be applied in small sensor devices or in electrodes for biosignal acquisition, such as those for electroencephalography or electromyography as it is the case of the main research area that is being developed in the group.

Evolution of the functional properties of titanium–silver thin films for biomedical applications: Influence of in-vacuum annealing

In this work, the thermal stability of TiAgx thin films, deposited by magnetron sputtering, was evaluated, envisaging their application in biomedical devices, namely as electrodes for biosignal acquisition. Based on the composition and microstructural characterization, a set of four representative TiAgx thin films was selected in order to infer whether they are thermally stable in terms of functional properties. In order to achieve this purpose, the structural and morphological evolution of the films with annealing temperature was correlated with their electrical, mechanical and thermal properties. Two distinct zones were identified and two samples from each zone were extensively analysed. In the first zone (zone I), Ti was the main component (Ti-rich zone) while in the second, zone II, the Ag content was more significant. The selected samples were annealed in vacuum at four different temperatures up to 500 oC. For the samples produced within zone I, small microstructural changes were observed due to the recrystallization of the Ti structure and grain size increment. Also, no significant changes were observed with annealing temperature regarding the f l ’ functional properties, being thermally stable up to 500 oC. For higher Ag contents (zone II) the energy supplied by thermal treatments was sufficient to activate the crystallization of Ti-Ag intermetallic phases. A strong increase of the grain size of these phases was also reported. The structural and morphological organization proved to be determinant for the physical responses of the TiAgx system. The hardness and Y g’s modulus were significantly improved with the formation of the intermetallic phases. The silver addition and annealing treatments also played an important role in the electrical conductivity of the films, which was once again improved by the formation of Ti-Ag phases. The thermal diffusivity of the films was practically unchanged with the heat-treatment. This set of results shows that this intermetallic-like thin film system has good thermal stability up to high temperatures (as high as 500 oC), which in case of the highest Ag content zone is particularly evident for electrical and mechanical properties, showing an important improvement. Hardness increases about three times, while resistivity values become half of those from the lowest Ag contents zone. These set of characteristics are consistent with the targeted applications, namely in terms of biomedical sensing devices.

Qualidade de vida de pacientes com esquizofrenia internados em hospital de custódia

OBJETIVO: Investigar a qualidade de vida (QV) de pacientes com o diagnóstico de esquizofrenia que cumprem medida de segurança em regime fechado. MÉTODOS: Estudo epidemiológico com delineamento transversal, realizado com pacientes de um hospital de custódia. As entrevistas foram conduzidas utilizando questionário sociodemográfico e a escala de qualidade de vida Quality of Life Scale (QLS-BR), específica para pacientes com diagnóstico de esquizofrenia. Foi realizada análise descritiva e multivariada. A associação entre os escores de QV e as características clínicas, sociodemográficas e do delito foi obtida por análise multivariada, através da árvore de decisão, por meio do algoritmo Chi-squared Automatic Interaction Detector (CHAID). RESULTADOS: Participaram deste estudo 54 pacientes, sendo 90,7% do sexo masculino, com a média de idade de 40 anos. Todos os domínios de qualidade de vida, inclusive o global, apresentaram escores compatíveis com uma QV muito baixa. O domínio ocupacional apresentou-se como o mais comprometido. Maior duração da doença, ter cometido homicídio e estar com idade superior a 40 anos foram as variáveis associadas a uma baixa qualidade de vida pela análise multivariada. CONCLUSÃO: Evidenciou-se uma baixa QV dos pacientes que cumprem medida de segurança em regime fechado, realidade que precisa ser modificada a partir da viabilização de mudanças nas políticas brasileiras.

Segmentação de imagens fetais com potencial para desenvolvimento de ferramentas de apoio ao diagnóstico

Programa Doutoral em Engenharia Eletrónica e de Computadores

Planeamento e controlo de projetos em ambiente colaborativo com recurso a ferramentas BIM

Dissertação de mestrado integrado em Engenharia Civil

Frequência de comportamentos alimentares inadequados e sua relação com a insatisfação corporal em adolescentes

OBJETIVO: Descrever a relação entre a frequência de insatisfação com a imagem corporal e a presença de sintomas de transtornos alimentares em adolescentes. MÉTODOS: O estudo foi realizado com uma amostra de 300 adolescentes, de ambos os sexos, na faixa etária de 10 a 17 anos, estudantes de uma escola pública estadual da cidade do Recife, Brasil. Foram utilizadas as versões brasileiras para adolescentes de três escalas autoaplicativas (EAT-26, BITE e BSQ), além de um questionário contendo dados biodemográficos. RESULTADOS: A frequência de sintomas de transtornos alimentares detectada pelo EAT-26 foi de 32,3%; 2,3% para comportamentos sugestivos de bulimia nervosa, por meio da escala BITE, tendo 36,67% dos alunos apresentado padrão alimentar não usual; 5,6% apresentaram insatisfação com a imagem corporal; 8,6% demonstraram tendência à preocupação com a insatisfação com a imagem corporal e 17,6% apresentaram leve insatisfação, além de 66,3%, que mostraram normalidade em relação à sua forma corporal. CONCLUSÃO: Os adolescentes apresentaram níveis de alteração na autoimagem corporal, com alta frequência de insatisfação da imagem corporal, podendo apresentar associação com comportamentos alimentares inadequados.

Indicadores chave de sustentabilidade para edifícios residenciais em estrutura metálica

Dissertação de mestrado integrado em Engenharia Civil

Aplicação da linha de equilíbrio no planeamento e controlo da construção

Dissertação de mestrado integrado em Engenharia Civil

Coordenação de segurança em obra: metodologia, técnicas e ferramentas

Dissertação de mestrado integrado em Engenharia Civil

Automatic distinction of Fernando Pessoas’ heteronyms

Text Mining has opened a vast array of possibilities concerning automatic information retrieval from large amounts of text documents. A variety of themes and types of documents can be easily analyzed. More complex features such as those used in Forensic Linguistics can gather deeper understanding from the documents, making possible performing di cult tasks such as author identi cation. In this work we explore the capabilities of simpler Text Mining approaches to author identification of unstructured documents, in particular the ability to distinguish poetic works from two of Fernando Pessoas' heteronyms: Alvaro de Campos and Ricardo Reis. Several processing options were tested and accuracies of 97% were reached, which encourage further developments.

Coordenação das MEP na implementação de modelos BIM

Dissertação de mestrado integrado em Engenharia Civil

An integrated model for simulation of construction phasing of arch concrete dams

Dissertação de mestrado integrado em Civil Engineering

Planeamento e controlo de projetos de construção com recurso ao BIM

Dissertação de mestrado integrado em Engenharia Civil