Browsing by Issue Date, starting with "2005-06"
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- Introdução à modelação dinâmica de sistemas ecológicosPublication . Aníbal, J.Os modelos matemáticos têm sido tradicionalmente utilizados como método de investigação em vários ramos da ciência, especialmente na química e na física com o objectivo de sintetizar o conhecimento existente ou de investigar fenómenos que ocorrem num dado sistema e para cálculo quantitativo e preditivo. Nos anos recentes a análise de sistemas estimulou o desenvolvimento de modelos matemáticos em limnologia e ciências afins devido ao crescente interesse por abordagens ecológicas mais quantitativas, e à necessidade urgente de uma gestão ambiental adequada, incluindo a capacidade preditiva da evolução de cada ecossistema face a alterações projectadas. Tal desenvolvimento deveu-se em grande parte ao acesso a computadores cada vez mais rápidos e a preços mais reduzidos e ao desenvolvimento de linguagens de programação mais acessíveis.
- Recupera Projecto 03/04 INOVAlgarve EST/ADEM Vale Montanha, LdaPublication . Nunes, Manuel; Sousa, NelsonNa sequência da política da UAlg e da EST de expandir os contactos e colaboração Universidade/Empresas da região, a Área Departamental de Engenharia Mecânica (ADEM) tem desenvolvido esforços quer na prestação de serviços com inúmeras empresas algarvias, quer no desenvolvimento de projectos de interesse comum. É neste último ponto que se insere o Projecto 03/04 - InovAlgarve RECUPERA – Caracterização Energética e Ambiental de Recuperadores de Calor para Lareiras desenvolvido através da parceria ADEM/Vale Montanha Lda. A empresa Vale Montanha, Serviços de Engenharia Lda. é uma empresa metalomecânica com sede em Portimão e especializada na fabricação de recuperadores de calor a lenha para lareiras [1]. Fundada em 1982 por um inglês que veio viver para o Algarve, fabrica actualmente cerca de 3000 aparelhos/ano principalmente para o mercado português mas pensando no mercado internacional nomeadamente o Norte Europeu. Neste contexto, a ADEM promoveu um acordo específico baseado no protocolo existente entre esta empresa e a Universidade. O acordo específico estabelecido permitiu avançar com a candidatura ao programa InovAlgarve financiado em 80% pelo FEDER sob a gestão da Comissão Coordenadora e do Desenvolvimento da Região do Algarve (CCDRAlgarve). Os restantes 20% foram financiados pela empresa Vale Montanha Lda. e pela ADEM.
- Dietary protein: lipid ratio and lipid nature affects fatty acid absorption and metabolism in a teleost larvaPublication . Morais, S.; Koven, W.; Ronnestad, I.; Dinis, Maria Teresa; Eugénio Castanheira Conceição, LuisStudies with teleost larvae have reported poor performance associated with quantitative lipid imbalances in the diet. The present study examined the effect of dietary protein:neutral lipid ratio on fatty acid (FA) absorption efficiency and metabolism in larval Senegalese sole. In addition, the effect of lipid class (triolein (TRI) and L-3-phosphatidylcholine-1,2-di-oleoyl (PC)), carbon number and degree of saturation of the labelled NEFA, stearic acid (SA), oleic acid (OA) and DHA) was tested. FA absorption was determined by tube feeding [1-C-14]-labelled lipids and NEFA after a single meal of either non-enriched Artemia (NEA) or Artemia enriched on a soyabean oil emulsion (EA), or after feeding these diets over an extended period of time (18 d). The tested dietary protein:lipid ratios had no short-term influence but long-term feeding of a diet higher in neutral lipid (EA) increased lipid accumulation within the gut epithelium and resulted in lower FA absorption (higher label evacuation and lower retention of dietary FA), which may partially explain the trend for lower growth observed with this diet. The lipids and NEFA, showed different digestive and metabolic properties, independent of feeding regime. FA absorption increased with unsaturation, being lowest for SA, followed by OA, and highest for DHA. In addition, sole larvae had a lower capacity to digest and absorb FA esterified to TRI, compared with PC, with the order of decreasing absorption being NEFA > PC >> TRI. Moreover, larvae appeared to discriminate between the source of OA, as this FA in the free form or esterified to PC was catabolised less than TRI.
- Rapid identification of differentially expressed genes by in situ screening of bacteriaPublication . Fonseca, V. G.; Lago-Lestón, Asunción; Laizé, Vincent; Cancela, LeonorThe identification of differentially expressed genes is a key step in the understanding of specific molecular mechanisms. Various methods have been developed to search for differences in expression but most of them are time or money consuming. We present here an alternative technique that connects standard suppression subtractive hybridization with in situ screening of bacteria to isolate and identify differentially expressed transcripts. The in situ differential screening is based on the transfer of bacteria directly from cultures onto nylon membranes with no need of phenol/chloroform extraction, colony lifting, or polymerase chain reaction amplification. This improved method was successfully applied and must be seen as a simple, low-cost, time-saving, and reproducible approach to identify differentially expressed genes.
- Relationships between nutrient composition of flowers and fruit quality in orange trees grown in calcareous soilPublication . Pestana, M; Beja, Pedro; Correia, PJ; De Varennes, A; Faria, EATo determine if flower nutrient composition can be used to predict fruit quality, a field experiment was conducted over three seasons (1996-1999) in a commercial orange orchard (Citrus sinensis (L.) Osbeck cv. 'Valencia Late', budded on Troyer citrange rootstock) established on a calcareous soil in southern Portugal. Flowers were collected from 20 trees during full bloom in April and their nutrient composition determined, and fruits were harvested the following March and their quality evaluated. Patterns of covariation in flower nutrient concentrations and in fruit quality variables were evaluated by principal component analysis. Regression models relating fruit quality variables to flower nutrient composition were developed by stepwise selection procedures. The predictive power of the regression models was evaluated with an independent data set. Nutrient composition of flowers at full bloom could be used to predict the fruit quality variables fresh fruit mass and maturation index in the following year. Magnesium, Ca and Zn concentrations measured in flowers were related to fruit fresh mass estimations and N, P, Mg and Fe concentrations were related to fruit maturation index. We also established reference values for the nutrient composition of flowers based on measurements made in trees that produced large (> 76 mm in diameter) fruit.
- Gestão estratégica da região de Lisboa e Vale do Tejo - Relatório 2Publication . Sousa, Vanessa Duarte de; Ferreira, António FonsecaO "Relatório 0" deu início ao processo de monitorização Estratégica da RLVT, constituindo um diagnóstico de partida que serve de referencial para a avaliação a desenvolver. O "Relatório I", editado um ano depois, e entendido como um "tableau de bord", dá conta das evoluções registadas na Região no período seguinte (2000-2001), e agora o "Relatório II", que aqui apresentamos, segue a lógica dos anteriores, no sentido em que se baseia num levantamento estatístico dos indicadores que sustentam as principais dimensões de análise selecionadas em cada um dos domínios de monitorização então definidos - Território, Pessoas e Organizações, para o período 2001-2002.
- On the relevance of the neurobiological analogue of the finite-state architecturePublication . Magnus Petersson, KarlWe present two simple arguments for the potential relevance of a neurobiological analogue of the finite-state architecture. The first assumes the classical cognitive framework, is well-known, and is based on the assumption that the brain is finite with respect to its memory organization. The second is formulated within a general dynamical systems framework and is based on the assumption that the brain sustains some level of noise and/or does not utilize infinite precision processing. We briefly review the classical cognitive framework based on Church-Turing computability and non-classical approaches based on analog processing in dynamical systems. We conclude that the dynamical neurobiological analogue of the finite-state architecture appears to be relevant, at least at an implementational level, for cognitive brain systems.
- Reproductive aspects of Microchirus azevia (Risso, 1810) (Pisces : Soleidae) from the south coast of PortugalPublication . Afonso-Dias, I; Reis, C; Andrade, José PedroFresh fish obtained from commercial landings in the harbours of Olhao and Quarteira (south Portugal) in 1998 and 1999, were examined in order to study different aspects of the reproductive biology of Microchirus azevia (Risso, 1810): spawning season, ovary maturation, length/age at first maturity and sex ratio. A five-stage maturity scale, based on external appearance was used to classify the ovaries. M. azevia is a winter-spring batch spawner with a protracted spawning season. Females outnumbered males in length classes greater than 19 cm and in all age groups. The estimated mean size at first maturity (L-50%) for females was 23 cm total length at 3 years of age (t(50%)).
- The interaction of social and steroidal influences in regulating transitons between adult sexual phenotypes.Publication . Grober, M. S.; Rodgers, E. W.; Denman, H. N.; Canario, Adelino V. M.Variation in adult sexual expression is common in a variety of vertebrate species and early exposure to steroid hormones mediates the development of sexual phenotype. For many fish species, social cues regulate transitions between adult alternative reproductive states, and changing levels of estrogens and androgens are thought to be key components of this process.
- Weaning of Senegalese sole (Solea senegalensis) postlarvae to an inert diet with a co-feeding regimePublication . Ribeiro, Laura; Engrola, S.; Dinis, MTThe objective of this study was to evaluate the weaning success of Senegalese sole, Solea senegalensis, postlarvae when co-fed a compound diet, by means of the analysis of growth parameters (relative growth rate [RGR] and condition factor [K]), survival, protein and lipid content. Total ammonia in the rearing water was also measured. The experiment lasted for 46 days (36 to 82 days posthatching). One group was fed only with enriched Artemia sp. metanauplii (Artemia treatment), whereas in another group, the Artemia sp. metanauplii were gradually replaced by the International Council for the Exploration of the Sea (ICES) diet over a period of 39 days (ICES treatment). Postlarvae were sampled on rearing days 0, 9, 23, 30, 39 and 46 for growth and biochemical analysis. Water was sampled on rearing day 30 during a 24-h cycle in both treatments. Postlarvae from the ICES treatment were weaned, though by the end of the experiment the Artemia treatment exhibited significantly higher values for growth, RGR, K and survival rates (P < 0.05). No significant differences were observed concerning total lipid content. Protein content was significantly higher for the Artemia treatment after 46 days of rearing (P < 0.05). The total ammonia nitrogen concentration in the water increased after each meal and remained below a harmless level for postlarvae.