A natureza sob o olhar da química: caracterizaçao de novas moléculas activas isoladas de productos naturais Açorianos

Jornadas "Ciência nos Açores – que futuro?", Ponta Delgada, 7-8 de Junho de 2013.

Avaliação do desempenho de um sistema híbrido de tomografia por emissão de positrões e tomografia computorizada

Mestrado em Medicina Nuclear.

A 5GHz1.8V Low Power CMOS Low-Noise Amplifier

Wireless local-area networks (WLANs) have been deployed as office and home communications infrastructures worldwide. The diversification of the standards, such as IEEE 802.11 series demands the design of RF front-ends. Low power consumption is one of the most important design concerns in the application of those technologies. To maintain competitive hardware costs, CMOS has been used since it is the best solution for low cost and high integration processing, allowing analog circuits to be mixed with digital ones. In the receiver chain, the low noise amplifier (LNA) is one of the most critical blocks in a transceiver design. The sensitivity is mainly determined by the LNA noise figure and gain. It interfaces with the pre-select filter and the mixer. Furthermore, since it is the first gain stage, care must be taken to provide accurate input match, low-noise figure, good linearity and a sufficient gain over a wide band of operation. Several CMOS LNAs have been reported during the last decade, showing that the most research has been done at 802.11/b and GSM standards (900-2400MHz spectrum) and more recently at 802.11/a (5GHz band). One of the more significant disadvantages of 802.11/b is that the frequency band is crowded and subject to interference from other technologies, as is 2.4GHz cordless phones and Bluetooth. As the demand for radio-frequency integrated circuits, operating at higher frequency bands, increases, the IEEE 802.11/a standard becomes a very attractive option to wireless communication system developers. This paper presents the design and implementation of a low power, low noise amplifier aimed at IEEE 802.11a for WLAN applications. It was designed to be integrated with an active balun and mixer, representing the first step toward a fully integrated monolithic WLAN receiver. All the required circuits are integrated at the same die and are powered by 1.8V supply source. Preliminary experimental results (S-parameters) are shown and promise excellent results. The LNA circuit design details are illustrated in Section 2. Spectre simulation results focused at gain, noise figure (NF) and input/output matching are presented in Section 3. Finally, conclusions and comparison with other recently reported LNAs are made in Section 4, followed by future work.

Desenvolvimento de tecnologias de extração e de quantificação dos principais componentes nutricionais de macroalgas do litoral dos Açores tendo em vista o seu aproveitamento como suplemento alimentar

Dissertação de Mestrado em Tecnologia e Segurança Alimentar

Water quality issues in rivers, lakes and reservoirs in Asian countries: an approach to the problems and the methodologies

Water covers over 70% of the Earth's surface, and is vital for all known forms of life. But only 3% of the Earth's water is fresh water, and less than 0.3% of all freshwater is in rivers, lakes, reservoirs and the atmosphere. However, rivers and lakes are an important part of fresh surface water, amounting to about 89%. In this Master Thesis dissertation, the focus is on three types of water bodies – rivers, lakes and reservoirs, and their water quality issues in Asian countries. The surface water quality in a region is largely determined both by the natural processes such as climate or geographic conditions, and the anthropogenic influences such as industrial and agricultural activities or land use conversion. The quality of the water can be affected by pollutants discharge from a specific point through a sewer pipe and also by extensive drainage from agriculture/urban areas and within basin. Hence, water pollutant sources can be divided into two categories: Point source pollution and Non-point source (NPS) pollution. Seasonal variations in precipitation and surface run-off have a strong effect on river discharge and the concentration of pollutants in water bodies. For example, in the rainy season, heavy and persistent rain wash off the ground, the runoff flow increases and may contain various kinds of pollutants and, eventually, enters the water bodies. In some cases, especially in confined water bodies, the quality may be positive related with rainfall in the wet season, because this confined type of fresh water systems allows high dilution of pollutants, decreasing their possible impacts. During the dry season, the quality of water is largely related to industrialization and urbanization pollution. The aim of this study is to identify the most common water quality problems in Asian countries and to enumerate and analyze the methodologies used for assessment of water quality conditions of both rivers and confined water bodies (lakes and reservoirs). Based on the evaluation of a sample of 57 papers, dated between 2000 and 2012, it was found that over the past decade, the water quality of rivers, lakes, and reservoirs in developing countries is being degraded. Water pollution and destruction of aquatic ecosystems have caused massive damage to the functions and integrity of water resources. The most widespread NPS in Asian countries and those which have the greatest spatial impacts are urban runoff and agriculture. Locally, mine waste runoff and rice paddy are serious NPS problems. The most relevant point pollution sources are the effluents from factories, sewage treatment plant, and public or household facilities. It was found that the most used methodology was unquestionably the monitoring activity, used in 49 of analyzed studies, accounting for 86%. Sometimes, data from historical databases were used as well. It can be seen that taking samples from the water body and then carry on laboratory work (chemical analyses) is important because it can give an understanding of the water quality. 6 papers (11%) used a method that combined monitoring data and modeling. 6 papers (11%) just applied a model to estimate the quality of water. Modeling is a useful resource when there is limited budget since some models are of free download and use. In particular, several of used models come from the U.S.A, but they have their own purposes and features, meaning that a careful application of the models to other countries and a critical discussion of the results are crucial. 5 papers (9%) focus on a method combining monitoring data and statistical analysis. When there is a huge data matrix, the researchers need an efficient way of interpretation of the information which is provided by statistics. 3 papers (5%) used a method combining monitoring data, statistical analysis and modeling. These different methods are all valuable to evaluate the water quality. It was also found that the evaluation of water quality was made as well by using other types of sampling different than water itself, and they also provide useful information to understand the condition of the water body. These additional monitoring activities are: Air sampling, sediment sampling, phytoplankton sampling and aquatic animal tissues sampling. Despite considerable progress in developing and applying control regulations to point and NPS pollution, the pollution status of rivers, lakes, and reservoirs in Asian countries is not improving. In fact, this reflects the slow pace of investment in new infrastructure for pollution control and growing population pressures. Water laws or regulations and public involvement in enforcement can play a constructive and indispensable role in environmental protection. In the near future, in order to protect water from further contamination, rapid action is highly needed to control the various kinds of effluents in one region. Environmental remediation and treatment of industrial effluent and municipal wastewaters is essential. It is also important to prevent the direct input of agricultural and mine site runoff. Finally, stricter environmental regulation for water quality is required to support protection and management strategies. It would have been possible to get further information based in the 57 sample of papers. For instance, it would have been interesting to compare the level of concentrations of some pollutants in the diferente Asian countries. However the limit of three months duration for this study prevented further work to take place. In spite of this, the study objectives were achieved: the work provided an overview of the most relevant water quality problems in rivers, lakes and reservoirs in Asian countries, and also listed and analyzed the most common methodologies.

Lingüística de corpus e estudos da tradução

O objectivo principal deste ensaio é discutir o interesse crescente que os Estudos da Tradução tem expressado acerca da Lingüística de Corpus e seu importante papel para a investigação do fenómeno tradutório. O ensaio apresenta os primeiros trabalhos na interface entre corpora e tradução e como a disciplina dos Estudos da Tradução de base em corpus evoluiu na última década. Uma atenção mais pontual é dada à noção de estudos em corpus de pequena dimensão e sua influência no campo das pesquisas em tradução no Brasil. Além disso, o ensaio explora como o conceito de representatividade tem recebido definições diferentes nos estudos dos fenómenos tradutórios de base em corpus.

Os retalhistas nas redes sociais : perceção dos consumidores

Dissertação de Mestrado em Ciências Económicas e Empresariais.

Redes sociais e a sua utilização no marketing

Dissertação de Mestrado em Ciências Económicas e Empresariais.

Antenas cornetas para o satélite CosmoGal

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Electrónica e Telecomunicações

Monitorização de cobre em vinhos verdes

A presente dissertação descreve o desenvolvimento e a caracterização de sensores potenciométricos com base em polímeros de impressão molecular e de sensores ópticos com base em membranas de poli(cloreto de vinilo), PVC, para a determinação de cobre em vinhos verdes. Os sensores potenciométricos foram preparados a partir de diferentes solventes (metanol e clorofórmio), tendo o seu crescimento decorrido na presença ou ausência da molécula molde (cobre). Os sistemas sensores selectivos ao cobre continham partículas de polímeros com ou sem impressão molecular como material electroactivo, dispersas em solvente plastificante, PVC e, em alguns casos, aditivo aniónico. A avaliação dos vários sistemas baseou-se na comparação das características operacionais dos diversos eléctrodos onde foram aplicados. Estas características foram obtidas a partir de curvas de calibração, cujos declives e limites de detecção variaram entre -39,9 – 37,0 mV decada-1 e 4,2 – 29,1 μg mL-1, respectivamente. Os sensores não são independentes do pH uma vez que o complexo formado entre o cobre e a difenilcarbazida é favorecido por valores de pH próximos de 5. Assim, obtiveram-se melhores resultados usando água desionizada ou solução tampão de HEPES revelando-se um método rápido e relativamente eficaz nestas condições. Os sensores ópticos basearam-se na reacção colorimétrica entre o cobre e um complexante. Os reagentes complexantes escolhidos foram a neocuproína, a difenilcarbazida e o dietilditiocarbamato de sódio. Avaliou-se o efeito de vários parâmetros experimentais na resposta destes sensores, tais como o pH (avaliado para os valores 3,00 e 5,00), a concentração de cobre (que variou entre 0,06 e 317,7 mg L- 1) e as próprias características da membrana. Os melhores resultados foram obtidos a pH 3, numa gama de concentrações de 0,06 e 31,8 mg L-1 usando a difenilcarbazida como reagente complexante. A aplicação destes sensores a vinhos requer ainda estudos adicionais, especialmente no que diz respeito à necessidade de implementar algum procedimento de pré-tratamento de amostra.

Resolução do problema do escalonamento da produção de energia eléctrica usando programação lógica por restrições

A operação dos Mercados de Energia Eléctrica passa, actualmente, por uma profunda reestruturação, com o principal foco nas transacções do sistema de transmissão entre os diferentes agentes. Tendo isso em conta, o serviço de transmissão neste novo esquema de funcionamento do Mercado de Energia Eléctrica deve ser provido de máxima eficiência económica, atendendo sempre às restrições de segurança do sistema. Com esta reorganização do sector eléctrico da última década surgiu também a necessidade de rever os modelos tradicionais de optimização económica do Sistema Eléctrico de Energia, como por exemplo o despacho e prédespacho (unit commitment). A reestruturação e liberalização dos mercados de energia eléctrica trouxeram novas restrições a alguns dos problemas tradicionais associados aos Sistemas Eléctricos de Energia. Um desses problemas é o Escalonamento da Produção de Energia Eléctrica, que no contexto actual, implica quase sempre negociação entre os diferentes agentes do mercado e consequentemente reescalonamento. A maioria dos métodos usados para a resolução do problema não permitem reformular o prédespacho, algo para que a Programação Lógica por Restrições é extremamente adequada. O trabalho desenvolvido nesta dissertação visa criar uma aplicação computacional com base na Programação Lógica por Restrições, através da plataforma ECLiPSe, para resolver o problema do Escalonamento da Produção de Energia Eléctrica dos grupos térmicos, demonstrando assim a versatilidade e flexibilidade deste tipo de programação aplicada a problema combinatoriais deste género.

Caracterização do potencial eólico urbano: o caso de Lisboa

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização em Edificações

Concorrência fiscal prejudicial

Mestrado em Fiscalidade

The 27th British liquid crystal society annual meeting 2013, Cambridge

Attending the British Liquid Crystal Society’s (BLCS) Annual Meeting was a formative experience in my days as a PhD student, starting way back in the 1990s. At that time, this involved travelling to (to me) exotic parts of the United Kingdom, such as Reading, Oxford or Manchester, away from Southampton where I was based. Some postdoctoral years in a different country followed, and three BLCS Meetings were missed, until in 1997 and 1998, I was able to attend again, in Southampton and Leeds, respectively. Not much had changed from my student days, the size and the format were still about the same, many of the leading characters were still around, and the closing talk would still be given by John Lydon. Well, at some point, I got myself a proper academic job on the Continent and stopped attending BLCS Annual Meetings altogether. The fond memories of my youth started to fade. Were the Meetings still on? It seemed so, as old friends and acquaintances would occasionally recount attending them, and even winning prizes at them. But, it all seemed rather remote now. Until, that is, it came to pass that the 27th BLCS Meeting would be held in Selwyn College, Cambridge, just down (or up, depending on how you look at it) the road from the Isaac Newton Institute, where I was spending part of my sabbatical leave. The opportunity to resume attendance could not be missed. A brief e-mail exchange with the organisers, and a cheque to cover the fee, duly secured this. And thus, it was with trepidation that I approached my first BLCS Annual Meeting in more than a decade.

A teoria dos detalhes luminosos de Ezra Pound e a teoria das cores e da vibração de Wassily Kandinsky: novas possibilidade exegéticas e tradutivas

O objectivo deste artigo é aplicar aos Estudos de Tradução Literária o binómio literatura-imagem com origem no Expressionismo alemão e no Vorticismo inglês, optando por um suporte teórico tão seminal quanto a ficcionalidade a que se destinava a expectativa programática dessas vanguardas, nas décadas dez e vinte do passado século. Da poética visual de Wassily Kandinsky, formulada em Über das Geistige in der Kunst - insbesondere in der Malerei [Do Espiritual na Arte](Kandinsky, 1912/1952), falarei da noção de Vibração. Da poética textual de Ezra Pound, exposta em ―I Gather the Limbs of Osiris‖ (1911/12), remeterei para a Teoria dos Detalhes Luminosos. São duas poéticas que, partindo de meios de expressão distintos – a imagem e a palavra, apresentam consideráveis pontos de contacto, no que diz respeito à abordagem produtiva e receptiva do objecto artístico. Ambas suspendem a procura convencional de um sentido na arte e na literatura, reunindo novas possibilidades exegéticas e, por conseguinte, tradutivas: a articulação entre a palavra poética e a imagem, com um amplo leque de possibilidades relativo a modos de estrutura perceptual, que se viriam a revelar proféticos, muito especialmente no que diz respeito à Tradução Artística, seja literária ou intersemiótica.