Two-phase auto-piloted synchronous motors and actuators

Imperial Users onl

Using presence-absence data to establish reserve selection procedures that are robust to temporal species turnover

Previous studies suggest that a network of nature reserves with maximum efficiency (obtained by selecting the minimum area such that each species is represented once) is likely to be insufficient to maintain species in the network over time. Here, we test the performance of three selection strategies which require presence-absence data, two of them previously proposed (multiple representations and selecting an increasing percentage of each species' range) and a novel one based on selecting the site where each species has exhibited a higher permanence rate in the past. Multiple representations appear to be a safer strategy than selecting a percentage of range because the former gives priority to rarer species while the latter favours the most widespread. The most effective strategy was the one based on the permanence rate, indicating that the robustness of reserve networks can be improved by adopting reserve selection procedures that integrate information about the relative value of sites. This strategy was also very efficient, suggesting that the investment made in the monitoring schemes may be compensated for by a lower cost in reserve acquisition

Vida de bicho: a fauna e o meio ambiente no Brasil.

As cartilhas dos jogos ambientais da Ema constituem um material que visa atender a Educação Ambiental de crianças e adultos.bitstream/item/128277/1/EMA-7-FAUNA.pdfProjeto Minibibliotecas

Dengue disease, basic reproduction number and control

Dengue is one of the major international public health concerns. Although progress is underway, developing a vaccine against the disease is challenging. Thus, the main approach to fight the disease is vector control. A model for the transmission of Dengue disease is presented. It consists of eight mutually exclusive compartments representing the human and vector dynamics. It also includes a control parameter (insecticide) in order to fight the mosquito. The model presents three possible equilibria: two disease-free equilibria (DFE) and another endemic equilibrium. It has been proved that a DFE is locally asymptotically stable, whenever a certain epidemiological threshold, known as the basic reproduction number, is less than one. We show that if we apply a minimum level of insecticide, it is possible to maintain the basic reproduction number below unity. A case study, using data of the outbreak that occurred in 2009 in Cape Verde, is presented.Comment: This is a preprint of a paper whose final and definitive form has appeared in International Journal of Computer Mathematics (2011), DOI: 10.1080/00207160.2011.55454

Healthrisk assessment from exposure to trihalomethanes in drinking water

A aplicação de compostos clorados na desinfeção da água pode induzir à formação de subprodutos da desinfeção (SPD) com efeitos carcinogénicos e mutagénicos comprovados. Neste trabalho, apresenta-se uma síntese de um estudo sobre a ocorrência de trihalometanos (THM) na água de abastecimento, realizado nos catorze municípios do distrito de Braga (Portugal), visando a avaliação do risco de cancro (RC) e de efeitos não carcinogénicos (HI) com base na metodologia desenvolvida pela USEPA e IRIS. Num cenário gravoso, correspondente à prevalência da maior concentração de THM detetada no período monitorizado, o indicador RC daria valores superiores ao limite máximo definido como negligenciável, verificando-se ser a ingestão a via de exposição mais relevante. Os resultados obtidos para o indicador HI foram quase sempre inferiores à unidade, indicando um nível de risco aceitável, de acordo com os pressupostos do método utilizado. O uso de indicadores do risco para a saúde constitui uma ferramenta útil quer no apoio à decisão das entidades gestoras de sistemas de abastecimento de água, quer na definição de estratégias e políticas de saúde pública que visem a mitigação deste risco.Chlorination havebroughtenormous benefits to the preservation of public health as a low-cost disinfection method, but it cangenerate severalhalogenated organic compounds,as disinfection by-products (DBP), with potentialand proven carcinogenic and mutagenic effects. This workpresents a synthesis of the study performed in watersupply systems ofthe fourteen municipalities of Braga district (Portugal), aiming at the evaluation of lifetime cancer risk (CRindex),and the risk of non-carcinogenic effects (HI-Hazard Index) fromexposure to THMs, usingamethod proposed by USEPA and IRIS.In a severescenario, corresponding to the prevalence of maximum THMconcentrationoccurred duringthe monitored period, the CR index would achieve valueshigher than the maximum limit defined asnegligible forall these municipalities. The HI indexresultswereoftenlower than one,which is consideredas an acceptable risk level. The use of health risk indicators can be a useful tool both in supporting the decision-making of water supplyutilitiesandin the definition of public health strategies/policies forrisk mitigation in order to increasethe life quality and the wellnessof populations