Métodos geofísicos de exploração aplicados ao estudo da perigosidade sísmica

Nas últimas décadas os métodos geofísicos ganharam papel de relevo na avaliação da perigosidade do risco sísmico e na sua mitigação. A detecção de falhas activas em ambientes intra placa onde as taxas de movimentação são relativamente baixas (<0,3 mm/ano) e as roturas superficiais são obliteradas pela erosão e sedimentação, levaram à utlização daqueles métodos na investigação paleossismológica. A nível da mitigação, em que a avaliação dos efeitos de sítio é essencial, é necessário um conhecimento das propriedades mecânicas das primeiras dezenas de metros da sub-superfície e da estrutura das bacias sedimentares, que são obtidos a partir de sondagens geotécnicas e métodos geofísicos. A utilização dos métodos sísmicos, eléctricos e electromagnéticos na identificação de falhas e na estrutura do subsolo, a delimitação de bacias a partir de métodos potenciais e a caracterização das propriedades mecânicas do subsolo são analisadas no presente trabalho, com exemplos de aplicação em Portugal

Improving the Knowledge on Seismogenic Sources in the Lower Tagus Valley for Seismic Hazard Purposes

The Lower Tagus Valley, that includes the metropolitan area of Lisbon, has been struck by several earthquakes which produced significant material damage and loss of lives. Their exact location remains unknown. Our goal is to shed some light into the seismogenic sources in the area using seismic reflection and geological data. In areas with no seismic coverage, potential-field data interpretation was carried out. Seismicity was overlaid to the potential seismogenic structures and high-resolution data was acquired in order to confirm which structures have been active into the Quaternary. Three major fault-zones affecting the Neogene were identified: V. F. Xira, Samora-Alcochete and Pinhal Novo. For the first fault, strong evidences suggest it is active. The other two fault-zones and other structures previously unknown can be correlated with several epicentres. Empirical relationships between maximum moment magnitude and fault area indicate that MW > 6.5 earthquakes can be expected for the larger structures

Aquisição de sinais electromiográficos recorrendo a eléctrodos em substratos têxteis

A electromiografia (EMG) constitui um método fundamental para o estudo do comportamento biomecânico de um indivíduo. Este artigo apresenta um estudo realizado na óptica do desenvolvimento de eléctrodos têxteis não invasivos para a realização de electromiografia de superfície. O trabalho apresenta um método de fabrico de eléctrodos, as suas vantagens e limitações e uma comparação entre dois tipos de eléctrodos têxteis e convencionais, utilizados neste tipo de medição. Os resultados obtidos indiciam um comportamento para estes eléctrodos têxteis considerado semelhante ao dos convencionais, podendo deste modo constituir uma alternativa válida, sobretudo quando se tem em consideração as vantagens que estes proporcionam.Fundação para a Ciência e a Tecnologia (FCT) - PTDC/EEA-ELC/70803/2006Universidade do Minh

Disfunção tiróidea e amiodarona

Although most patients remain clinically euthyroid, some develop amiodarone-induced hyperthyroidism (HPEAI) or hypothyroidism (HPOAI). The authors present a retrospective analysis of ten patients with amiodarone-induced thyroid dysfunction. Six patients were female and mean amiodarone intake was 17.7 months. HPOIA was more common (six patients). From all the patients with HPEAI, two had type 2, one had type 1, and one had type 3 hyperthyroidism. Symptoms suggestive of thyroid dysfunction occurred in five patients, most of them with HPOAI. In HPEAI, the most frequent symptom was exacerbation of arrhythmia (three patients). Discontinuation of amiodarone and treatment with levothyroxine was chosen in 83.3% of the HPOAI cases, while thyonamide treatment with corticosteroids and without amiodarone was the option in 75% of the HPEAI cases. There were three deaths, all in patients with HPEAI. HPEAI is potentially fatal. The clinical picture may be vague, so the thyroid monitoring is mandatory

Biosignal monitoring implemented in a swimsuit for athlete performance evaluation

Monitor athletes during exercise has always been a major challenge for engineers and researchers due to the restrictions involving the measurement of physiological and performance parameters. An athlete should have complete freedom to perform his normal activity, in order to be correctly monitored. The advent of e-textiles can give an important contribution to overcome these limitations since it is possible to integrate sensors in garments and thus perform monitoring without limiting the freedom of movements. This paper presents part of the work that is being carried out in the project entitled BIOSWIM, which envisions the development of an instrumented swimsuit, capable of acquiring several physiological and performance related signals with the purpose of aiding the trainer in improving the technical component of the swimmer and improve his performance. This paper will give an overview of the monitoring system and the textile sensors that were developed, namely for biopotential measurement.Fundação para a Ciência e a Tecnologia (FCT) - projeto Bioswim (PTDC/EEAELC/70803/2006

Pegmatite productive terrains in the Variscan Granite hosts from Northern and Central Portugal

The detection of suboutcropping pegmatite deposits in regions recognizably fertile regarding the occurrence of pegmatites depends upon the optimization of conceptual models which support the interpretation of the regional distribution of pegmatites and the structure of their assemblies. In intra-granitic context is at concern the more conventional cartographic expression of pegmatites in connection with the structuring of granitic cupolas. The establishment of occurrence situations linked to certain lithological units or structural alignments is a pathway for the delimitation of productive research areas. Some productivity situations deduced from geological mapping include: accommodation in preferred structural directions, proximity to mixing-mingling corridors, certain petrographic structuring units that reflect irregularities in terms of flow and fractionation processes, and trends of hydrothermal and supergene alteration of host granitic masses. The detection of these aspects, to regard as exploration guides, can avail itself of remote sensing, as they represent contrasting chromatic lithotypes with sufficient surface continuity.(undefined

Neotectonic activity on the Carcavai fault zone (Algarve, Portugal)

Studies performed on the Carcavai fault zone, Eastern Algarve, revealed several deformational features in Plio-Quaternary sediments with potential neotectonic implications. These features include fracturing (faults and joints) and clastic dikes, located along the Carcavai fault. Most of the fractures appear to be the expression of the fault activity affecting the Plio-Quaternary sediments. This is suggested by a consistent strike, subparallel to the major tectonic structure, and by the location pattern. Evidences of the fault activity were also identified in the Mesozoic and Paleozoic rocks, though the age of that deformation is poorly constrained. It consists in the presence of zones of intensely brecciated rock and of adjoining coarse sedimentary deposits probably related to the dismantling of a fault scarp. The acquired data point to a late hercynian structure, reactivated as a left-lateral strike-slip fault with a thrust component during the Plio-Quaternary