108 resultados para statistical spatial analysis


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Este artigo tem por objetivo identificar padrões na distribuição espacial dos casos de dengue ocorridos no município de Cruzeiro/SP, no ano de 2006. Trata-se de um estudo ecológico e exploratório que utiliza as ferramentas de análise espacial na elaboração de mapas temáticos, com dados obtidos do SinanNet. Foi feita uma análise por área, tomando-se como unidade o setor censitário do IBGE; a análise considerou quatro meses do ano de 2006 que mostra a ocorrência da doença no município. Os mapas temáticos foram construídos pelo programa computacional TerraView 3.3.1; assim como os valores dos índices de Moran Global (I M) mês a mês e o estimador de Kernel. Foram georreferenciados 691 casos de dengue (taxa de 864,2 casos/100.000 habitantes); os Índices de Moran e p-valores obtidos foram I M = 0,080 (março) p = 0,11; I M = 0,285 (abril) p = 0,01; I M = 0,201 (maio) p = 0,01 e I M = 0,002 (junho) p = 0,57. Os primeiros casos foram identificados na região nordeste e central e os últimos casos, na região norte, nordeste e central. Foi possível identificar os setores censitários onde a epidemia teve início e como ocorreu têmporo-espacialmente no município.

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Using food bait stations and colony trap nests, the spatial relation between the foraging activity of established colonies of the polygynous and unicolonial exotic pharaoh's ant, Monomorium pharaonis, and colonization by colony fragments was studied over an 8 month period in a large institutional setting in Brazil. Both foraging activity and colonizations demonstrated significant spatial clumping. However, colonizations were significantly negatively clumped spatially with respect to foraging activity. This suggests that the colonization strategy of this species under the studied conditions was that of complete habitat domination.

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Considering the textbooks, papers and articles published during the last decades, this paper deals with the development of the quantitative analysis in Geography. The comments are grouped into the following thematic questions: contributions aiming to introduce concepts and techniques in the geographical issues, focusing statistical and mathematical background and specific techniques about spatial and temporal distributions; contributions evaluating the potentialities of the quantification; contributions showing the character and applicability of the quantificative techniques, and the state of the use of these techniques in Brazilian literature and teaching. -English summary

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The biological control of Diatraea saccharalis is regarded as one of the best examples of successful classical biological control in Brazil. Since the introduction of the exotic parasitoid, Cotesia flavipes, the decrease in D. saccharalis infestation in sugarcane fields has been attributed to the effectiveness of this agent. Native Tachinidae fly parasitoids (Lydella minense and Paratheresia claripalpis) have also been implicated in the success. Quantitative data confirming the actual contribution of these agents to the control of D. saccharalis are, however, rather scant. The purpose of this study was to investigate the spatial pattern of parasitism of these parasitoids in D. saccharalis populations at two large spatial scales (fields and zones). To investigate this subject, a large data set comprising information collected from a sugarcane mill located in the state of São Paulo, Brazil (São João sugarcane mill) was analysed. When regressions between the proportion parasitism against host density were computed, the percentage of significant regressions with either a positive or a negative slope was very small at both spatial scales for both parasitoid species. Regressing the densities of tachinid-parasitized hosts against host densities per field showed that these parasitoids presented a 'moderate aggregative' response to host densities, as 53.33% of the regressions were positively significant. Cotesia flavipes was 'weakly aggregated' on host densities at the field level, because only 33.33% of the regressions were positively significant. At the zone level, neither aggregative nor spatial proportion parasitism responses were evident for either parasitoid species due to the small percentage of significant regressions computed.

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How individual-level movement decisions in response to habitat edges influence population-level patterns of persistence and spread of a species is a major challenge in spatial ecology and conservation biology. Here, we integrate novel insights into edge behavior, based on habitat preference and movement rates, into spatially explicit growth-dispersal models. We demonstrate how crucial ecological quantities (e.g., minimal patch size, spread rate) depend critically on these individual-level decisions. In particular, we find that including edge behavior properly in these models gives qualitatively different and intuitively more reasonable results than those of some previous studies that did not consider this level of detail. Our results highlight the importance of new empirical work on individual movement response to habitat edges. © 2013 by The University of Chicago.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Geociências e Meio Ambiente - IGCE

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OBJETIVO Analisar mudanças espaciais no risco de Aids e a relação entre incidência da doença e variáveis socioeconômicas. MÉTODOS Estudo caso-controle espacial, de base populacional, realizado em Rondônia, Brasil, com 1.780 casos notificados pelo Sistema de Vigilância Epidemiológica e os controles a partir de dados demográficos de 1987 a 2006. Os casos foram agrupados em cinco períodos de cinco anos consecutivos. Um modelo aditivo generalizado foi ajustado aos dados. O status dos indivíduos (caso ou controle) foi considerado como a variável dependente e independente: um alisamento ( spline ) bidimensional das coordenadas geográficas e variáveis socioeconômicas municipais. Os valores observados para o teste Moran I foram comparados com a distribuição de referência dos valores obtidos em condições de aleatoriedade espacial. RESULTADOS O risco de Aids apresentou padrão espacial e temporal marcado. A incidência associou-se a indicadores socioeconômicos municipais, como urbanização e capital humano. As maiores taxas de incidência de Aids ocorreram em municípios ao longo da rodovia BR-364; os resultados do teste Moran I mostram correlação espacial positiva associada à contiguidade dos municípios com a rodovia, no terceiro e quarto períodos (p = 0,05). CONCLUSÕES A incidência da doença foi maior em municípios de maior riqueza econômica e urbanização e naqueles cortados pelas estradas principais de Rondônia. O rápido desenvolvimento associado à ocupação de regiões remotas pode ser acompanhado por aumento de riscos à saúde.

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The objective of this study was to define a method for estimating soybean crop area in the Northern Rio Grande do Sul state (Brazil). Overall, six different remote sensing methods were proposed based on spectral-temporal profile and minimum and maximum values of NDVI/MODIS related to the stages of sowing, maximum development and harvesting of soybean areas. The resulting estimates were compared to official crop area data provided by the Brazilian government, using statistical analysis and the fuzzy similarity method. The performance of each method depended on information such as crop size, type of crop management, and sowing/harvesting dates. Regression coefficients of determination and fuzzy agreement values were above 0.8 and 0.45, respectively, for all methods. For operational monitoring of soybean crop area, the empirical threshold applied to the image difference with inclusion of harvest image method was the most effective, producing estimates that matched closely the official data. For spatial analysis the application of multitemporal images classification method is recommended that generated a map of better quality. The efficiency of these methods should be evaluated in the areas of soybean expansion in the state.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Aim The aim of this study was to understand the biogeography of Brachygastra. As the spatial component of evolution is of fundamental importance to understanding the processes shaping the evolution of taxa, the known geological history of the Neotropical region was used together with the current phylogeny and distribution of species to investigate questions concerning the biogeography of Brachygastra: the ancestral ranges of Brachygastra species; their areal relationships and their congruence with previously published hypotheses; the possible associated vicariance events and the influence of land bridges between North and South America, and the split between the Amazon and Atlantic forests. Location Neotropical region, from Mexico to central Argentina and southern USA. Methods Statistical dispersal–vicariance analysis (S-DIVA) was used to reconstruct the possible ancestral ranges of Brachygastra species based on their phylogeny (divided into three groups, lecheguana, scuttelaris and smithii). A Brooks parsimony analysis (BPA) and component analysis were performed to reconstruct the areal relationships of these species within the Neotropics. Results S-DIVA suggested a widespread, South American ancestral region for Brachygastra. The ancestral B. azteca probably reached the Nearctic before a posterior vicariance event separated it from the species groups ((lecheguana (scutellaris + smithii))), that stayed in the Atlantic forest. The ancestral (scutellaris + smithii groups) possibly reached the Amazon by dispersal, and the subsequent vicariance event splitting the Atlantic forest and Amazon separated the groups into scutellaris in the Atlantic forest and smithii in the Amazon. BPA and component analyses suggested that the Nearctic was a sister area to other regions, the Andes and Mesoamerica was a sister area to the Neotropical regions and the Amazon was closely related to the Atlantic forest. Main conclusions The phylogeny and distribution of Brachygastra suggest the influence of a land bridge between the Northern and Southern Hemispheres affecting the cladogenesis of B. azteca and the importance of the formation of the two blocks of forests in South America to the cladogenesis of the main groups of Brachygastra. Future comparisons between the distribution patterns of other taxa should enable a more precise identification of the possible events and outcomes, adding robustness to the hypothesized areal relationships.