22 research outputs found
Seroprevalence of malaria in inhabitants of the urban zone of Antananarivo, Madagascar
BACKGROUND: Antananarivo, the capital of Madagascar, is located at an altitude of over 1,200 m. The environment at this altitude is not particularly favourable to malaria transmission, but malaria nonetheless remains a major public health problem. The aim of this study was to evaluate exposure to malaria in the urban population of Antananarivo, by measuring the specific seroprevalence of Plasmodium falciparum. METHODS: Serological studies specific for P. falciparum were carried out with an indirect fluorescent antibody test (IFAT). In a representative population of Antananarivo, 1,059 healthy volunteers were interviewed and serum samples were taken. RESULTS: The seroprevalence of IgG+IgA+IgM was 56.1% and that of IgM was 5.9%. The major risk factor associated with a positive IgG+IgA+IgM IFAT was travel outside Antananarivo, whether in the central highlands or on the coast. The abundance of rice fields in certain urban districts was not associated with a higher seroprevalence. CONCLUSION: Malaria transmission levels are low in Antananarivo, but seroprevalence is high. Humans come into contact with the parasite primarily when travelling outside the city. Further studies are required to identify indigenous risk factors and intra-city variations more clearly
Reversible translocation of cytidylyltransferase between cytosol and endoplasmic reticulum occurs within minutes in whole cells
Differential activation by fMet-Leu-Phe and phorbol ester of a plasma membrane phosphatidylcholine-specific phospholipase D in human neutrophil
Forest mapping in tropical region using multitemporal and interferometric ERS-1/2 data
European Space Agency, (Special Publication) ESA SP414 PART 1351-356ESPU
Uso de imagens de radar para o cálculo da produção primária de plantas aquáticas nas várzeas da Amazônia Use of radar imagery for estimating net primary productivity of aquatic vegetation in the Amazon floodplain
A área da planície de inundação da Amazônia é estimada em 300 000km² e sua produtividade primária em 1,17 x 10(14) g C yr-1. Deste total de área e produtividade, estimativas sugerem que 43% e 62%, respectivamente, são atribuídos às plantas aquáticas. Estas estimativas variam de acordo com o pulso de inundação. Por exemplo, durante o período de seca as plantas terrestres (herbáceas) geralmente ocupam áreas que apresentam plantas aquáticas na cheia. A área e a produtividade destes ecossistemas são informações essenciais para a compreensão da dinâmica biogeoquímica da Amazônia. Imagens de satélites (radar) combinadas com amostragem de campo foram utilizadas para estimar a biomassa e mapear a área de cobertura de plantas aquáticas emergentes para calcular a produção primária de plantas aquáticas na várzea do baixo Amazonas. A combinação de bandas C e L forneceu a melhor correlação (r=0,82) e um ponto de saturação de biomassa intermediário (620 gm-2) para estimar biomassa aérea. O método de segmentação e classificação por região foi utilizado para classificar combinações de bandas C e L para cada período de nível de água, e forneceu uma precisão de mapeamento maior que 95% para determinação espacial de áreas cobertas por plantas aquáticas. Combinando a distribuição espacial de plantas aquáticas, o modelo para estimativa de biomassa aérea e a porcentagem de biomassa submersa, estimou-se espacialmente uma produção primária líquida anual de 1.9x10(12) g C yr-1 (±28%) para as plantas aquáticas em uma área de 394km².<br>Estimates suggest that 43% and 63% of the 300,000km² of Amazon floodplain area and of the 1.17 x 10(14) g C yr-1 of primary productivity, respectively, are attributed to the aquatic vegetation. These numbers change according to the flood pulse. For instance, in the dry season terrestrial herbaceous plants generally occupy areas that have lost their aquatic vegetation. The areal extent and productivity of these ecosystems are essential to construe even an initial understanding of the biogeochemistry of the Amazon. Field measurements were combined with synthetic aperture radar images to evaluate the use of RADARSAT and JERS-1 for estimating biomass changes and mapping of aquatic vegetation, and subsequently estimating the net primary productivity of aquatic vegetation in the lower Amazon. The combination of C and L bands provides the best correlation (r =0.82) and an intermediate saturation point (620 gm-2) for estimating above water biomass of aquatic vegetation. A combination of RADARSAT and JERS-1 images from each water period was classified using a region growing algorithm, and yielded accuracy higher than 95% for the seasonal vegetated areas of the floodplain. The combination of the seasonal mapped area of aquatic vegetation with the statistical SAR-algorithm for estimating above water biomass and the percentage of below water biomass yielded a total annual NPP of 1.9x10(12) g C yr-1 (±28%) for aquatic vegetation