Browsing by Issue Date, starting with "2009-10"
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- Fronteira Pliocénico-Plistocénico: estudo de caso nas formações detríticas do AlgarvePublication . Moura, Delminda; Boski, T.; Veiga-Pires, C.; Mariano, J.Na região do Algarve, a sedimentação pós Miocénico foi quase exclusivamente detrítica e a escassez de horizontes cronológicos torna muito difícil posicionar a fronteira Neogénico-Quaternário (FNQ). Com base na magnetostratigrafia e na interpretação das fácies sedimentares, propõe-se no presente trabalho que seja considerada como FNQ a inversão de polaridade Gauss-Matuyama, uma vez que ocorre no seio de um sistema regressivo que poderá corresponder à instalação de condições de glacial no Hemisfério Norte.
- Dietary lipid level affects growth performance and nutrient utilisation of Senegalese sole (Solea senegalensis) juvenilesPublication . Borges, Pedro; Oliveira, Beatriz; Casal, Susana; Dias, Jorge; Conceicao, Luis; Valente, Luisa M. P.Over the last few years, several aspects of Senegalese sole (Solea senegalensis) culture have been developed and optimised but the dietary lipid level for optimal growth has never been determined. Hence, five isonitrogenous diets (56 % dietary protein) with increasing dietary lipid levels (4, 8, 12, 16 and 20 % DM) were fed to satiation to triplicate groups of twenty fish (mean initial weight 10 g). Fifteen tanks were randomly assigned one of the five diets. Feed was distributed using automatic feeders, and fish were fed over a 16-week period. At the end of the experiment the fish fed on diets containing the two lowest dietary lipid levels (4 and 8 %) showed a 3-fold body-weight increase with a significantly higher daily growth index than fish fed higher lipid levels (1-2 v. 0-8). Moreover, these fish displayed a significantly lower dry feed intake (12g/kg per d) and feed conversion ratio (1-0) compared with fish fed higher lipids levels (16-19 g/kg per d; feed conversion ratio 2-0). Low dietary lipid levels (< 12 %) significantly improved nutrient retention and gain and hence growth, without major effects on whole-body composition. Despite the slight alteration in n-3 PUFA muscle content in the fish fed low-fat-diets, this fish fed low dietary lipid still remains a rich n-3 PUFA product and generally maintained its nutritional value. These results evidenced a low lipid tolerance of Senegalese sole juveniles and suggest a maximal dietary inclusion level of 8 % lipids for both optimal growth and nutrient utilisation without compromising flesh quality.
- M. Teixeira-Gomes e o AlgarvePublication . Carvalho, Ana Alexandra Mendonça Seabra da Silva Andrade deNeste Ciclo de Conferências intitulado "Viajantes, Escritores e Poetas - Retratos do Algarve", a figura de Manuel Teixeira-Gomes pareceu-me obrigatória. Não tanto por se tratar de um ilustre algarvio, que, para além de escritor, foi um distinto diplomata e exemplar presidente da República portuguesa...
- Iterative detection of multicode DS-CDMA signals with strong nonlinear distortion effectsPublication . Dinis, Rui; Silva, PauloWhenever a direct-sequence code-division multiple-access (DS-CDMA) signal is the sum of several components associated with different spreading codes [e.g., the DS-CDMA signal to be transmitted by the base station (BS) in the downlink or any multicode DS-CDMA signal], it has high envelope fluctuations and a high peak-to-mean envelope power ratio (PMEPR), setting strong linearity requirements for the power amplifiers. For this reason, it is desirable to reduce the envelope fluctuations of the transmitted signals. The use of clipping techniques combined with frequency-domain filtering was shown to be an effective way of reducing the envelope fluctuations (and, inherently, the PMEPR) of DS-CDMA signals, while maintaining the spectral occupation of the corresponding conventional DS-CDMA signals. To avoid PMEPR regrowth effects, the clipping and filtering operations can be repeated several times. However, the performance degradation due to nonlinear distortion effects on the transmitted signals can be relatively high, particularly when a very low PMEPR is intended (e.g., when a low clipping level and several iterations are adopted). This can particularly be serious if different powers are assigned to different spreading codes. To avoid significant performance degradation in these situations, we consider an improved receiver where there is an iterative estimation and cancellation of nonlinear distortion effects. Our performance results show that the proposed receiver allows significant performance improvements after just a few iterations, even when we have strong nonlinear distortion effects.
- Phosphoglucose isomerase variability of Cerastoderma glaucum as a model for testing the influence of environmental conditions and dispersal patterns through quantitative ecology approachesPublication . Gonzalez-Wangueemert, Mercedes; Canovas, Fernando; Marcos, Concepcion; Perez-Ruzafa, AngelExtreme conditions of coastal lagoons could directly modify the genetic patterns of species. The aim of this work was to investigate the influence of environmental conditions and small scale dispersal patterns on the phosphoglucose isomerase (PGI*) genetic variability of Cerastoderma glaucum from the Mar Menor coastal lagoon. For this purpose, 284 cockles were collected around the perimeter of the lagoon. Vertical polyacrylamide gel electrophoresis was used to scan for PGI* polymorphisms, giving a total of seven alleles. The spatial genetic distribution of the PGI* variability, which seems to be marked by the main circulation in the lagoon, discriminates four hydrological basins. In the central basin, a gradient of allelic composition reflects the circulation forced by the dominant winds and the main channel communicated to the open sea. This result is well supported by the salinity GAM model that defines this gradient. The other three basins are defined by the distribution of fine sand in a more complex model that tries to explain the isolation of the three sites localized inside these basins. The southern, western and northern basins show the lowest degree of interconnection and are considered the most confined areas of the Mar Menor lagoon. This situation agrees with the confinement theory for benthic assemblages in the lagoon. The greater degree of differentiation seen in the Isla del Ciervo population is probably due to recent human intervention on the nearby Marchamalo channel, which has been drained in recent years thus altering the influence of the Mediterranean Sea on the southern basin.
- Imagens do Algarve nas narrativas de viagemPublication . Carvalho, João Carlos Firmino Andrade deO género literatura de viagens abrange um acervo textual muito vasto e heterogéneo, desde o texto literário propriamente dito ao texto claramente não-literário, passando por aquele texto em que as fronteiras entre o literário e o não-literário são indeferíveis.
- Viajantes, escritores e poetas. Retratos do AlgarvePublication . Carvalho, João Carlos Firmino Andrade de; Oliveira, CatarinaO livro que agora se apresenta ao Leitor reúne as versões escritas de dezasseis conferências, proferidas por professores e investigadores de três Universidades (Universidade do Algarve; Universidade Nova de Lisboa e Faculdade de Letras da Universidade de Lisboa), por escritores e poetas que abordaram obras de outros escritores e poetas algarvios ou o seu próprio universo poético, bem como por mestrandos e doutorandos de Literatura da Faculdade de Ciências Humanas e Sociais da Universidade do Algarve que desenvolvem investigação associada às teses que se encontram a redigir. O Leitor tem agora à sua disposição as versões escritas, às quais pode dedicar o seu próprio tempo de leitura, (re)visitando os assuntos das conferências noutra perspectiva – precisamente enquanto Leitor.
- Plastid genomes of two brown algae, Ectocarpus siliculosus and Fucus vesiculosus: further insights on the evolution of red-algal derived plastidsPublication . Le Corguillé, Gildas; Pearson, G. A.; Valente, Marta; S B Viegas, Carla; Gschloessl, Bernhard; Corre, E.; Bailly, Xavier; Peters, Akira F.; Jubin, Claire; Vacherie, Benoit; Cock, J. Mark; Leblanc, CatherineBackground: Heterokont algae, together with cryptophytes, haptophytes and some alveolates, possess red-algal derived plastids. The chromalveolate hypothesis proposes that the red-algal derived plastids of all four groups have a monophyletic origin resulting from a single secondary endosymbiotic event. However, due to incongruence between nuclear and plastid phylogenies, this controversial hypothesis remains under debate. Large-scale genomic analyses have shown to be a powerful tool for phylogenetic reconstruction but insufficient sequence data have been available for red-algal derived plastid genomes. Results: The chloroplast genomes of two brown algae, Ectocarpus siliculosus and Fucus vesiculosus, have been fully sequenced. These species represent two distinct orders of the Phaeophyceae, which is a major group within the heterokont lineage. The sizes of the circular plastid genomes are 139,954 and 124,986 base pairs, respectively, the size difference being due principally to the presence of longer inverted repeat and intergenic regions in E. siliculosus. Gene contents of the two plastids are similar with 139-148 protein-coding genes, 28-31 tRNA genes, and 3 ribosomal RNA genes. The two genomes also exhibit very similar rearrangements compared to other sequenced plastid genomes. The tRNA-Leu gene of E. siliculosus lacks an intron, in contrast to the F. vesiculosus and other heterokont plastid homologues, suggesting its recent loss in the Ectocarpales. Most of the brown algal plastid genes are shared with other red-algal derived plastid genomes, but a few are absent from raphidophyte or diatom plastid genomes. One of these regions is most similar to an apicomplexan nuclear sequence. The phylogenetic relationship between heterokonts, cryptophytes and haptophytes (collectively referred to as chromists) plastids was investigated using several datasets of concatenated proteins from two cyanobacterial genomes and 18 plastid genomes, including most of the available red algal and chromist plastid genomes. Conclusion: The phylogenetic studies using concatenated plastid proteins still do not resolve the question of the monophyly of all chromist plastids. However, these results support both the monophyly of heterokont plastids and that of cryptophyte and haptophyte plastids, in agreement with nuclear phylogenies.