Browsing by Issue Date, starting with "2008-01"
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- Stochastic networks with multiple stable pointsPublication . Antunes, Nelson; Fricker, Christine; Robert, Philippe; Tibi, DanielleThis paper analyzes stochastic networks consisting of a set of finite capacity sites where different classes of individuals move according to some routing policy. The associated Markov jump processes are analyzed under a thermodynamic limit regime, that is, when the networks have some symmetry properties and when the number of nodes goes to infinity. An intriguing stability property is proved: under some conditions on the parameters, it is shown that, in the limit, several stable equilibrium points coexist for the empirical distribution. The key ingredient of the proof of this property is a dimension reduction achieved by the introduction of two energy functions and a convenient mapping of their local minima and saddle points. Networks with a unique equilibrium point are also presented.
- José Cardoso Pires, Lavagante. Encontro DesabitadoPublication . Carmo, Carina Infante doRecensão de Lavagante de José Cardoso Pires
- Les "logiques" du racisme dans la société portugaise contemporainePublication . Marques, João FilipeLe Portugal ne semble pas être une exception en matiére d'attitudes et de comportements racistes, observables dans la plupart des pays d'Europe.
- Rebuilding viable spawner patches of the overfished Spisula solida (Mollusca : Bivalvia): a preliminary contribution to fishery sustainabilityPublication . Joaquim, Sandra; Gaspar, Miguel; Matias, Domitilia; Ben-Hamadou, Radhouan; Arnold, William S.Populations of commercially important bivalves along the coast of Portugal are depleted as a consequence of natural and anthropogenic causes. A pilot experiment was designed to determine the feasibility of transplanting individuals from natural clam beds to a closed fishing area in an effort to rebuild relatively high-density patches of Spisula solida. For this purpose, clams were equally partitioned into two groups (undersize and legal clams) and transplanted at a density of 40 clams m(-2) into two areas 50 m(2). Transplanted and control clams were sampled to estimate survival, condition index, biochemical composition, and reproductive condition. Generally, the physiological condition of clams was not affected by the method of transplanting. One year after transplanting, survival was 45%. The increase in local abundance of mature clams should facilitate successful fertilization and increase the residual reproductive value of each clam relative to its pre-transplant value. Transplanting undersize clams may be more advantageous because they are more likely to spawn at least once before harvest. The experiments demonstrate that spawner transplants may strengthen S. solida populations and can be used in stock-enhancement programmes which, in conjunction with effective management measures, can contribute to the sustainability of the S. solida fishery.
- Essential oils of flowers of Citrus sinensis and Citrus clementina cultivated in Algarve, PortugalPublication . Miguel, Maria Graça; Dandlen, S.; Figueiredo, A. C.; Barroso, J. G.; Pedro, L. G.; Duarte, Amílcar; Faísca, J.The essential oils, isolated by hydrodistillation, from the flowers of different cultivars of Citrus sinensis (L.) Osbeck (Cs) and Citrus clementina Hort. Ex Tan. (Cc) collected at different harvesting times, were analyzed by GC and GC-MS. All the samples studied afforded yellowish oil which yields ranged from 0.05 to 0.08 % (v/w). The monoterpene fraction dominated both oils (66-91%), being the monoterpene hydrocarbons the main components of this fraction (45-69%). Sabinene (31-48%), linalool (15-32%) and limonene (4-10%) dominated both Cs and Cc oils. trans-Nerolidol was the major sesquiterpene component, attaining 3-10%. Cluster analysis of the essential oil composition from the twelve samples studied, confirmed a major chemical homogeneity (Scorr>0.95) despite the fact of having used different periods of hydrodistillation, different harvesting times and being flowers of two different Citrus species.
- Os efeitos fiscais do investimento na rede ferroviária de alta velocidadePublication . Pereira, Alfredo; Andraz, Jorge MiguelO investimento previsto na rede de alta velocidade gera efeitos macroeconómicos e fiscais que tornam possível assegurar o crescimento económico a longo prazo, sem colocar em causa o objectivo de consolidação orçamental a curto prazo. O efeito fiscal total acumulado excede largamente o valor correspondente a 36% do volume total do investimento que se prevê, no contexto actual, que seja financiado pelo Estado. Finalmente, os resultados apontam para que cerca de 74,2% do efeito total acumulado nas receitas fiscais, seja obtido durante a fase de construção. Nesse sentido, o Estado fica em condições de proceder de imediato ao pagamento da parcela que lhe cabe no financiamento da infra-estrutura durante a fase de construção da mesma.
- Qualidade de vida e suporte social em doentes hemodialisadosPublication . Silva, Inês de Assunção Costa Mestre Silva; Ribeiro, José Luís PaisThis work is about the quality of life and the social support in hemodialised patients. The autor wants to know how the social support affects the quality of life of these patients and understand how this items relate each other.