Browsing by Issue Date, starting with "2004-11"
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- Os programas de Português: uma questão também de políticaPublication . Carmo, Carina Infante doMuito se tem dito e escrito sobre o assunto que ficou associado à caricata inclusão num manual do regulamento do Big Brother. Já no período de discussão pública, em 2003, aquela proposta, emanada do governo PS, suscitou justificada contestação, o que, todavia, não convenceu o ministro David Justino a suspender o processo, desculpando-se ele com os danos financeiros que tal decisão acarretaria para as editoras escolares.
- The demise of the pearl fisheries in Tuticorin, Tamil Nadu (India): social and biological aspects and their application towards a sustainable management for the chank fisheries and condition improvement of the associated diver fisherfolkPublication . Santos, Sara Vanessa Freitas da Silva; Erzini, Karim; Bavinck, MaartenGlobally, changes are being felt in the fisheries sector, with a strong drive for maximizing catches on one hand and lack of resilience and recovery of stocks on the other. In India, too, habitat loss and reduced resource abundance are contemporary issues of concem, with great focus being put on the fishing populations dependent on the sea for maintaining a livelihood. Tuticorin is a coastal city of the south-eastem state of Tamil Nadu which supports a strong fishing tradition and, historically, is the centre for the world-famous pearl fisheries. These treasures of the sea are collected by divers who depend on the catch of an altemative resource - the sacred chank Xancus pyrum - for their regular source of income. At present, the pearl oyster Pinctadafucara can not support a fishery and chank stocks are also suffering accentuated declines. The divers of Therespuram fishing village, where the greatest percentage ofthese professionals can be found today, convey disappointment towards their current conditions and show concem for their future and that oftheir descendents. The pearl fisheries were taken as a case study in the present document and were used for the purpose of creating a base of foundations which, in tum, was put to practice through the suggestion of basic management strategies for the chank fisheries, throughout which the diving community was given utmost importance. The major part of the information narrated throughout this thesis was obtained through the accounts of divers, with the research taking the fonn of a qualitative social study.
- Calcium handling in Sparus auratus: effects of water and dietary calcium levels on mineral composition, cortisol and PTHrP levelsPublication . Abbink, W.; Bevelander, G. S.; Rotllant, J.; Canario, Adelino V. M.; Flik, G.Juvenile gilthead sea bream (Sparus auratus L.; 10–40·g body mass) were acclimatized in the laboratory to full strength (34‰) or dilute (2.5‰) seawater and fed normal, calcium-sufficient or calcium-deficient diet for nine weeks. Mean growth rate, whole-body calcium and phosphorus content and accumulation rates were determined, as well as plasma levels of ionic and total calcium, cortisol and parathyroid hormone related protein (PTHrP; a hypercalcemic hormone in fish). When confronted with limited calcium access (low salinity and calcium-deficient diet), sea bream show growth arrest. Both plasma cortisol and PTHrP increase when calcium is limited in water or diet, and a positive relationship was found between plasma PTHrP and plasma ionic calcium (R2=0.29, N=18, P<0.05). Furthermore, a strong correlation was found between net calcium and phosphorus accumulation (R2=0.92, N=16, P<0.01) and between body mass and whole-body calcium (R2=0.84, N=25, P<0.01) and phosphorus (R2=0.88, N=24, P<0.01) content. Phosphorus accumulation is strongly calcium dependent, as phosphorus accumulation decreases in parallel to calcium accumulation when the diet is calcium deficient but phosphorus sufficient. We conclude that PTHrP and cortisol are involved in the regulation of the hydromineral balance of these fish, with growthrelated calcium accumulation as an important target.
- Sustainability, complexity and water managementPublication . Pires Rosa, ManuelaConsidering the complexity and the uncertainties of social and natural systems and the present sustainable vision, it seems that the contemporary planning are no longer pertinent. We need adopting ecosystem approaches that converge to adaptive and collaborative approaches which emphasise active public participation and social learning. For its realization it is necessary to build collaborative and adaptive capacity. Adaptive management corresponds to a permanent and continuous, prospective, interactive system and of a constant reformulation process, which needs coordination of the activities, of the people and resources, besides dealing with innovation and change.
- Time reversal and spatial diversity: issues in a time varying geometry testPublication . Jesus, S. M.; Silva, A.Underwater acoustic communications in waveguides is known to be prone to severe multipath, which strongly limits practical transmission rates with actual channel equalization techniques. The time reversal principle uses the ocean waveguide response to a basic pulse shape to matched filter the received data sequence. Assuming the ocean response to be a version of the actual pulse shape ocean response corrupted by additive noise, the matched filter output remains a sum of four terms from which only one has the required data sequence in usable form. This paper analysis the ability of such a peculiar matched filter to reject the unwanted terms both with fixed and timevarying source-receiver geometries. One particular parameter with practical interest is the sensitivity of the matched filter performance to a change of the source-receiver range during the processing that induces a mismatch limiting factor. Simulation examples in realistic situations and results obtained with real data, collected during the INTIFANTE’00 sea trial, illustrate the theoretical assertions.