529 research outputs found
Contaminação por mercúrio em sedimento e moluscos da Bacia do rio Bento Gomes, MT.
Os níveis de mercúrio total detectados no sedimento e tecidos moles de moluscos gastrópodos provenientes da bacia hidrográfica do rio Bento Gomes, embora baixos, mostraram indícios de contaminação. De um total de 69 amostras de sedimento analisadas, 26% apresentaram níveis de mercúrio total variando de 0,01 a 0,25 µg.g-1 de mercúrio (peso úmido). Os níveis de mercúrio obtidos em 54 amostras dos moluscos Ampullaria scalaris; A. canaliculata e Marisa planogira evidenciaram que 39% estavam contaminadas com níveis variando de 0,02 a 1,6 µg.g-1 de peso úmido. Estes resultados indicam que o mercúrio utilizado na extração de ouro de aluvião está atingindo o ambiente aquático e contaminado o sedimento e os organismos bentônicos desta área do Pantanal.bitstream/item/37304/1/BP58.pd
Criação e manejo de capivaras em pequenas propriedades rurais.
bitstream/item/201693/1/Criacao-e-manejo.pdf; bitstream/item/201693/1/Criacao-e-manejo.pd
Assumptions for long-term stochastic population forecasts in 18 European countries: Hypothèses de projections stochastiquesàlong terme des populations de 18 pays européens
The aim of the ‘Uncertain Population of Europe’(UPE) project was to compute long-term stochastic (probabilistic) population forecasts for 18 European countries. We developed a general methodology for constructing predictive distributions for fertility, mortality and migration. The assumptions underlying stochastic population forecasts can be assessed by analysing errors in past forecasts or model-based estimates of forecast errors, or by expert judgement. All three approaches have been used in the project. This article summarizes and discusses the results of the three approaches. It demonstrates how the—sometimes conflicting—results can be synthesized into a consistent set of assumptions about the expected levels and the uncertainty of total fertility rate, life expectancy at birth of men and women, and net migration for 18 European countries
Utilização de biochar para mitigação das emissões de óxido nitroso do solo.
Com o avanço das mudanças climáticas ocasionadas pelo aquecimento global, faz-se necessário a busca por soluções que visem mitigar as emissões de gases de efeito estufa. O presente estudo objetivou avaliar o uso de biochar como prática para mitigar as emissões de óxido nitroso (N2O) gerado pela aplicação de fertilizante nitrogenado no solo. O biochar pode ser uma alternativa com potencial para mitigar as emissões de N2O provenientes do solo e o presente trabalho indica que doses acima de 6 Mg ha-1 trariam efeitos positivos
Monitoring international migration flows in Europe. Towards a statistical data base combining data from different sources
The paper reviews techniques developed in demography, geography and statistics that are useful for bridging the gap between available data on international migration flows and the information required for policy making and research. The basic idea of the paper is as follows: to establish a coherent and consistent data base that contains sufficiently detailed, up-to-date and accurate information, data from several sources should be combined. That raises issues of definition and measurement, and of how to combine data from different origins properly. The issues may be tackled more easily if the statistics that are being compiled are viewed as different outcomes or manifestations of underlying stochastic processes governing migration. The link between the processes and their outcomes is described by models, the parameters of which must be estimated from the available data. That may be done within the context of socio-demographic accounting. The paper discusses the experience of the U.S. Bureau of the Census in combining migration data from several sources. It also summarizes the many efforts in Europe to establish a coherent and consistent data base on international migration.
The paper was written at IIASA. It is part of the Migration Estimation Study, which is a collaborative IIASA-University of Groningen project, funded by the Netherlands Organization for Scientific Research (NWO). The project aims at developing techniques to obtain improved estimates of international migration flows by country of origin and country of destination
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Basic theory behind parameterizing atmospheric convection
Last fall, a network of the European Cooperation in Science and Technology (COST), called “Basic Concepts for Convection Parameterization in Weather Forecast and Climate Models” (COST Action ES0905; see http://w3.cost.esf.org/index.php?id=205&action_number=ES0905), organized a 10-day training course on atmospheric convection and its parameterization. The aim of the workshop, held on the island of Brac, Croatia, was to help young scientists develop an in-depth understanding of the core theory underpinning convection parameterizations. The speakers also sought to impart an appreciation of the various approximations, compromises, and ansatz necessary to translate theory into operational practice for numerical models
Widespread forest vertebrate extinctions induced by a mega hydroelectric dam in lowland Amazonia
Mega hydropower projects in tropical forests pose a major emergent threat to terrestrial and freshwater biodiversity worldwide. Despite the unprecedented number of existing, underconstruction and planned hydroelectric dams in lowland tropical forests, long-term effects on biodiversity have yet to be evaluated. We examine how medium and large-bodied assemblages of terrestrial and arboreal vertebrates (including 35 mammal, bird and tortoise species) responded to the drastic 26-year post-isolation history of archipelagic alteration in landscape structure and habitat quality in a major hydroelectric reservoir of Central Amazonia. The Balbina Hydroelectric Dam inundated 3,129 km2 of primary forests, simultaneously isolating 3,546 land-bridge islands. We conducted intensive biodiversity surveys at 37 of those islands and three adjacent continuous forests using a combination of four survey techniques, and detected strong forest habitat area effects in explaining patterns of vertebrate extinction. Beyond clear area effects, edge-mediated surface fire disturbance was the most important additional driver of species loss, particularly in islands smaller than 10 ha. Based on species-area models, we predict that only 0.7% of all islands now harbor a species-rich vertebrate assemblage consisting of ≥80% of all species. We highlight the colossal erosion in vertebrate diversity driven by a man-made dam and show that the biodiversity impacts of mega dams in lowland tropical forest regions have been severely overlooked. The geopolitical strategy to deploy many more large hydropower infrastructure projects in regions like lowland Amazonia should be urgently reassessed, and we strongly advise that long-term biodiversity impacts should be explicitly included in pre-approval environmental impact assessments
Lateral hypothalamic activity indicates hunger and satiety states in humans
Lateral hypothalamic area (LHA) local field potentials (LFPs) were recorded in a Prader–Willi patient undergoing deep brain stimulation (DBS) for obesity. During hunger, exposure to food-related cues induced an increase in beta/ low-gamma activity. In contrast, recordings during satiety were marked by prominent alpha rhythms. Based on these findings, we have delivered alphafrequency DBS prior to and during food intake. Despite reporting an early sensation of fullness, the patient continued to crave food. This suggests that the pattern of activity in LHA may indicate hunger/satiety states in humans but attest to the complexity of conducting neuromodulation studies in obesity
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