Marine tenure in the Wellesley Islands region, Gulf of Carpentaria

Tese de mestradoÉ consensual que as áreas costeiras são consideradas territórios de elevada importância estratégica em termos ambientais, económicos e sociais. Do mesmo modo são também reconhecidos os seus problemas e ameaças. A crescente pressão demográfica e concentração de atividades nestes espaços, cria problemas e conflitos de difícil solução, e ameaça destruir o seu delicado equilíbrio. A artificialização, associada a uma rápida expansão da indústria e do turismo nas regiões do litoral, particularmente intensa nos países desenvolvidos e nos países emergentes com alta taxa de crescimento, provoca uma inquietação generalizada sobre a sustentabilidade destas áreas. A necessidade de ordenar os usos e atividades neste espaço, conduziu ao aparecimento de sucessivos instrumentos legais, estratégias e planos de ação, numa grande diversidade e frequente desarticulação de políticas e de intervenções. Reconhece-se atualmente que os sistemas litorais são demasiado complexos para serem geridos por meio de políticas sectoriais, pelo que uma gestão integrada destes espaços afigura-se como a melhor forma para compatibilização de fatores e interesses divergentes. Trata-se de um processo flexível de gestão que visa o desenvolvimento sustentável destas regiões, e este exige que os recursos do litoral sejam salvaguardados em quantidade e qualidade, de modo a satisfazer as necessidades atuais sem pôr em causa o seu usufruto pelas gerações vindouras. Em Portugal o ordenamento e a gestão destas áreas assentam num conjunto de instrumentos e programas de natureza vinculativa ou orientadora que têm como objetivo estabelecer as regras a que deve obedecer a ocupação, uso e transformações dos solos. Este trabalho propõe como problemática central perceber a forma como se processou a ocupação da orla costeira, no caso particular de São Martinho do Porto, as potencialidades, os problemas e ameaças que sobre ela pendem, e o impacto que as políticas e instrumentos de gestão tiveram no rumo que essa ocupação seguiu

Search for R-Parity Violating Decays of Scalar Fermions at LEP

A search for pair-produced scalar fermions under the assumption that R-parity is not conserved has been performed using data collected with the OPAL detector at LEP. The data samples analysed correspond to an integrated luminosity of about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An important consequence of R-parity violation is that the lightest supersymmetric particle is expected to be unstable. Searches of R-parity violating decays of charged sleptons, sneutrinos and squarks have been performed under the assumptions that the lightest supersymmetric particle decays promptly and that only one of the R-parity violating couplings is dominant for each of the decay modes considered. Such processes would yield final states consisting of leptons, jets, or both with or without missing energy. No significant single-like excess of events has been observed with respect to the Standard Model expectations. Limits on the production cross- section of scalar fermions in R-parity violating scenarios are obtained. Constraints on the supersymmetric particle masses are also presented in an R-parity violating framework analogous to the Constrained Minimal Supersymmetric Standard Model.Comment: 51 pages, 24 figures, Submitted to Eur. Phys. J.

Colour reconnection in e+e- -> W+W- at sqrt(s) = 189 - 209 GeV

The effects of the final state interaction phenomenon known as colour reconnection are investigated at centre-of-mass energies in the range sqrt(s) ~ 189-209 GeV using the OPAL detector at LEP. Colour reconnection is expected to affect observables based on charged particles in hadronic decays of W+W-. Measurements of inclusive charged particle multiplicities, and of their angular distribution with respect to the four jet axes of the events, are used to test models of colour reconnection. The data are found to exclude extreme scenarios of the Sjostrand-Khoze Type I (SK-I) model and are compatible with other models, both with and without colour reconnection effects. In the context of the SK-I model, the best agreement with data is obtained for a reconnection probability of 37%. Assuming no colour reconnection, the charged particle multiplicity in hadronically decaying W bosons is measured to be (nqqch) = 19.38+-0.05(stat.)+-0.08 (syst.).Comment: 30 pages, 9 figures, Submitted to Euro. Phys. J.

Search for the Standard Model Higgs Boson with the OPAL Detector at LEP

This paper summarises the search for the Standard Model Higgs boson in e+e- collisions at centre-of-mass energies up to 209 GeV performed by the OPAL Collaboration at LEP. The consistency of the data with the background hypothesis and various Higgs boson mass hypotheses is examined. No indication of a signal is found in the data and a lower bound of 112.7GeV/C^2 is obtained on the mass of the Standard Model Higgs boson at the 95% CL.Comment: 51 pages, 21 figure

Measurement of the Michel Parameters in Leptonic Tau Decays

The Michel parameters of the leptonic tau decays are measured using the OPAL detector at LEP. The Michel parameters are extracted from the energy spectra of the charged decay leptons and from their energy-energy correlations. A new method involving a global likelihood fit of Monte Carlo generated events with complete detector simulation and background treatment has been applied to the data recorded at center-of-mass energies close to sqrt(s) = M(Z) corresponding to an integrated luminosity of 155 pb-1 during the years 1990 to 1995. If e-mu universality is assumed and inferring the tau polarization from neutral current data, the measured Michel parameters are extracted. Limits on non-standard coupling constants and on the masses of new gauge bosons are obtained. The results are in agreement with the V-A prediction of the Standard Model.Comment: 32 pages, LaTeX, 9 eps figures included, submitted to the European Physical Journal