790 research outputs found

    TVDI spatiotemporal pattern of a soybean growing area in humid subtropical climate

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    The most southern Brazilian state, Rio Grande do Sul, is characterized by high crop yield and is, currently, the third leading soybean producer in the country. Therefore, agriculture is very important to the economy of the region. Because agriculture is highly dependent on variable weather parameters, the present study aimed to test the Temperature-Vegetation Dryness Index (TVDI) as a regional indicator of water status under the climate and soybean crop management conditions that predominate in northwestern Rio Grande do Sul. For this, soybean crop seasons with contrasting yields were selected: 2004 – 2005 (yield 0.5 t·ha–1) and 2009 – 2010 (2.7 t·ha–1). TVDI was obtained from the surface temperature (TS) and Normalized Difference Vegetation Index (NDVI) images available from MODIS products, which were correlated to obtain a triangular scatter plot. Rainfall data from surface weather stations were also used. The results showed that the pattern of the TVDI is associated with rainfall variability. However, as the TVDI is based on normalization of the wet and dry edges of each image individually, the comparison of TVDI values across different images is challenging. This deficiency can be mitigated by analysis of the parameters used to derive the index. Therefore, both the TVDI and the “b” and TSmin parameters used to derive it can elucidate the patterns of crop response to water availability

    Metodologia de espacialização dos componentes do balanço de energia usando dados MODIS e ERA Interim

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    This work aims at proposing a methodology to spatialize the Energy Balance (EB) components from the combined use of MODIS sensor products and ERA-Interim reanalysis data, and to evaluate the performance of the OSEB and METRIC models for estimating EB components in the predominantly humid subtropical climate of Rio Grande do Sul, Brazil. The research was conducted for 3 consecutive years from 2009 to 2011. The temporal variation patterns of the EB components were analyzed by comparing the values estimated by the models against the reference measurements of a micrometeorological tower (Sulflux network). For the spatial variability analysis, reference evapotranspiration (ETo) was calculated at a local scale (data from Weather stations of the National Institute of Meteorology) and a regional scale (ERA-Interim reanalysis data) while the consistency between these estimates was also verified. Afterward, using only the pixels in which the sensible heat flux represented more than 50% of the radiation balance, correlation maps between ETo ERA-Interim and latent heat fluxes were constructed. The estimated BE components are consistent regarding both, the order of magnitude and variation throughout the year, when compared to the reference measurements of the micrometeorological tower. The spatial variability analyses also reveal satisfactory results for both models, however, the METRIC model results showed greater coherence since it provided a greater number of dates with consistent results, thus being indicated as the most suitable model for building the time series.O objetivo deste trabalho foi propor uma metodologia para a espacialização dos componentes do Balanço de Energia (BE) a partir do uso conjugado de produtos do sensor MODIS e dados de reanálise ERA Interim e avaliar o desempenho das estimativas geradas pelos modelos OSEB e METRIC nas condições de clima subtropical úmido que predominam no Rio Grande do Sul, Brasil. O período de estudo foi de 3 anos consecutivos, de 2009 a 2011. Os padrões de variação temporal dos componentes do BE foram analisados comparando os valores estimados pelos modelos frente às medidas de referência de uma torre micrometeorológica (rede Sulflux). Para análise de variabilidade espacial foi calculada a evapotranspiração de referência (ETo) em escala local (dados de estações meteorológicas do Instituto Nacional de Meteorologia) e em escala regional (dados de reanálise ERA Interim) e verificada a coerência entre estas estimativas. Após, utilizando somente os pixels em que fluxo de calor sensível representava mais do que 50% do saldo de radiação, foram construídos mapas de correlação entre ETo ERA Interim e fluxo de calor latente. As estimativas dos componentes do BE apresentam coerência, tanto na ordem de magnitude, como na variação ao longo do ano quando comparadas às medidas de referência da torre micrometeorológica. As análises de variabilidade espacial também apresentaram resultados satisfatórios para ambos modelos, porém o modelo METRIC apresentou maior coerência e proporcionou um maior número de datas com resultados consistentes, sendo, assim, indicado como o modelo mais apto para a construção da série temporal

    Differential trajectories of tobacco smoking in people at ultra-high risk for psychosis: Associations with clinical outcomes

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    Objective: People at ultra-high risk (UHR) for psychosis have a high prevalence of tobacco smoking, and rates are even higher among the subgroup that later develop a psychotic disorder. However, the longitudinal relationship between the course of tobacco smoking and clinical outcomes in UHR subjects is unknown. Methods: We investigated associations between tobacco smoking and clinical outcomes in a prospective study of UHR individuals (n = 324). Latent class mixed model analyses were used to identify trajectories of smoking severity. Mixed effects models were applied to investigate associations between smoking trajectory class and the course of attenuated psychotic symptoms (APS) and affective symptoms, as assessed using the CAARMS. Results: We identified four different classes of smoking trajectory: (i) Persistently High (n = 110), (ii) Decreasing (n = 29), (iii) Persistently Low (n = 165) and (iv) Increasing (n = 20). At two-year follow-up, there had been a greater increase in APS in the Persistently High class than for both the Persistently Low (ES = 9.77, SE = 4.87, p = 0.046) and Decreasing (ES = 18.18, SE = 7.61, p = 0.018) classes. There were no differences between smoking classes in the incidence of psychosis. There was a greater reduction in the severity of emotional disturbance and general symptoms in the Decreasing class than in the High (ES = −10.40, SE = 3.41, p = 0.003; ES = −22.36, SE = 10.07, p = 0.027), Increasing (ES = −11.35, SE = 4.55, p = 0.014; ES = −25.58, SE = 13.17, p = 0.050) and Low (ES = −11.38, SE = 3.29, p = 0.001; ES = −27.55, SE = 9.78, p = 0.005) classes, respectively. Conclusions: These findings suggests that in UHR subjects persistent tobacco smoking is associated with an unfavorable course of psychotic symptoms, whereas decrease in the number of cigarettes smoked is associated with improvement in affective symptoms. Future research into smoking cessation interventions in the early stages of psychoses is required to shine light on the potential of modifying smoking behavior and its relation to clinical outcomes.</p

    Evaluation of OSEB and SEBAL models for energy balance of a crop area in a humid subtropical climate

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    This study evaluated the adequacy of the One-Source Energy Balance (OSEB) and Surface Energy Balance Algorithm for Land (SEBAL) models to estimate evapotranspiration in grain growing areas with humid subtropical climate in Rio Grande do Sul, southern Brazil. The dataset was obtained from a micrometeorological station (Eddy Covariance) and MODIS (Moderate Resolution Imaging Spectroradiometer) products during 84 observation days between 2009 and 2011. The OSEB and SEBAL models were used to estimate the partition of net radiation (Rn) into the components latent heat flux (LE), sensible heat flux (H), and ground heat flux (G) estimated from the MODIS images while the experimental data measured in situ were used to compare the results. Analyses indicated that the Energy Balance (EB) components were estimated from the MODIS images satisfactorily despite the spatial resolution limitations. Furthermore, the SEBAL model estimated the EB components satisfactorily only for summer crops. There are uncertainties associated with determining the hot and cold pixels due to the region humid subtropical climate and the spatial resolution of the sensor used in the other periods. The OSEB model has the lowest errors and the most adequate partitioning of the EB components throughout the year, and therefore, it is the most suitable for the climatic conditions of Rio Grande do Sul

    Endocardite infecciosa (EI) com diagnóstico feito apenas à necrópsia: análise de 31 casos ocorridos entre 1992 e 1997, em Ribeirão Preto, Brasil

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    Thirty one infective endocarditis (IE) fatal cases whose diagnosis was first obtained at autopsy were studied. The clinical data of these patients (Group 1) showed significant differences compared to other 141 IE cases (Group 2). The average age of 53 years in Group 1 patients was 18 years higher than that of Group 2. The Group 1 patients had a low frequency of IE predisposing heart disease. Both patient groups presented fever (about 87%), but a significant low frequency of cardiac murmur (25.8%) was observed in Group 1 patients and echocardiography tests were performed in only 16.1%, suggesting that IE diagnosis was not suspected. Likewise, although most Group 1 patients appeared with severe acute illness, they did not present the classic IE clinical presentation. Blood cultures were performed in only 64.5% of the Group 1 patients. However, bacteria were isolated in 70% of these blood cultures and Staphylococcus aureus was isolated in 71.4%. The bacteria attacked mitral and aortic valves. Complications such as embolizations and cardiac failure occurred in almost half of the cases and they also presented with infections of the lungs, urinary tract, and central nervous system. Medical procedures were performed in practically all fatal cases whose diagnosis was first obtained at autopsy. Sepsis occurred in about half of the patients and it was followed by shock in more than 25%. This form of IE must be suspected in mature and in old febrile hospitalized patients having infection predisposing diseases, embolization, and suffering medical procedures.Trinta e um casos fatais de EI, que tiveram este diagnóstico apenas à necrópsia, foram analisados. Os dados clínicos destes pacientes (Grupo 1) mostrou diferenças significantes quando comparados aos de outros 141 casos de EI (Grupo 2). A idade média de 53 anos nos pacientes do Grupo 1 foi 18 anos mais alta que nos do Grupo 2. Os pacientes do Grupo 1 tiveram uma baixa freqüência de cardiopatias predisponentes à EI. Ambos os grupos de pacientes apresentaram febre (aproximadamente 87%), mas uma significante baixa freqüência de sopro cardíaco (25,8%) foi observado no Grupo 1, provavelmente, em conseqüência disto, o ecocardiograma foi efetuado em apenas 16,1% dos casos, não sendo, portanto, suspeitada EI. Os pacientes do Grupo 1, embora tivessem grave enfermidade aguda, não apresentaram apresentação clínica compatível com EI clássica. Hemoculturas foram feitas em apenas 64,5% dos pacientes do Grupo 1, porém, isolou-se bactérias em 70% e dentre os isolados, predominou o Staphylococcus aureus (71,4%). Foram predominantemente acometidas as válvulas mitral e aórtica. Complicações como embolização e insuficiência cardíaca ocorreram em quase metade dos casos e eles também apresentaram infecções pulmonares, urinárias e do sistema nervoso central. Praticamente todos os casos fatais de EI, que tiveram este diagnóstico apenas à necrópsia, foram submetidos a procedimentos médicos. Sepse aconteceu em aproximadamente metade dos pacientes e mostrou-se acompanhada de choque em mais de 25%. Esta forma de EI deve ser suspeitada em pacientes de idade madura ou idosos, hospitalizados, com doenças que predispõem a infecções, com embolização e que sofreram procedimentos médicos

    Uso do índice TVDI e modelo HAND para caracterização de condição hídrica

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    O objetivo do trabalho foi avaliar a adequação do índice TVDI (Temperature Vegetation Dryness Index), obtido com sensores remotos orbitais, para caracterizar a condição hídrica de lavouras de soja no sul do Brasil. Para tanto, foram utilizadas imagens do satélite Landsat 8- OLI, obtidas da base de dados da USGS (United States Geological Survey), de três datas ao longo do ciclo da cultura da soja (5 de dezembro 2014 – implantação, 6 de janeiro 2015 - início de desenvolvimento e 7 de fevereiro de 2015 – pleno desenvolvimento vegetativo). A área de cultivo de soja foi mapeada utilizando classificação digital (máxima verossimilhança) e validada com dados de campo. A área total mapeada foi estratificada em duas classes: áreas de várzea e áreas altas, através do uso do modelo HAND (Height Above the Nearest Drainage). Para tornar possível a comparação entre datas, o TVDI foi determinado usando um triângulo único para as três datas em conjunto, estabelecido a partir dos dados do NDVI (Normalized Difference vegetation Index) e da temperatura de superfície (TS), a qual foi estimada usando o algoritmo split-window. O TVDI permitiu diferenciar as condições hídricas na cultura da soja ao longo do ciclo e entre as classes de altitude; as áreas mais altas apresentaram maiores déficits quando comparadas às áreas de várzea. Foi possível ainda visualizar a migração dos pixels de soja dentro do triângulo evaporativo como consequência da fase de desenvolvimento da cultura e das condições hídricas.This work aims to evaluate the suitability of the Temperature Vegetation Dryness Index (TVDI), achieved through an orbital remote sensing system used to describe the condition of the water to be used on soybean crops in the South Region of Brazil. The Landsat 8-OLI satellite images were gathered from the USGS (United States Geological Survey) database of three different dates during the soybean crop cycle (December 5 th , 2014 - implementation, January 6 th , 2015 - beginning of growth and February 7 th , 2015 - full vegetative growth). The soybean crop area was mapped using digital classification (maximum likelihood method) and validated with field data. The total mapped area was stratified into two classes: floodplain areas and high areas, using the HAND (Height Above the Nearest Drainage) model. To make the comparison between dates possible, TVDI was determined using a single triangle for all the three dates together, established using the Normalized Difference Vegetation Index (NDVI) and surface temperature (TS) data, which was estimated using Split-window algorithm. TVDI allowed us to differentiate the water conditions during the soybean crop cycle and between the two altitude classes; the higher areas presented larger deficits when compared to the floodplain areas. It was also possible to observe the migration of the soybean pixels within the evaporative triangle as a consequence of the crop’s development stage and the water conditions
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