920 resultados para physical soil characteristics


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A recuperação de áreas degradadas é um processo lento e requer a adição de resíduos orgânicos como condicionador das propriedades físicas do solo. O lodo de esgoto apresenta elevados teores de matéria orgânica (MO) e nutrientes e, portanto, tem alto potencial para utilização nessas áreas. O objetivo deste trabalho foi verificar o efeito da adição de lodo de esgoto na recuperação das características físicas de um solo degradado (Neossolo Quartzarênico) plantado com espécies nativas da Mata Atlântica, na Fazenda Entre-Rios, pertencente à Cia. Suzano Bahia Sul de Papel e Celulose, na região de Itatinga-SP. O experimento foi conduzido em blocos casualizados com quatro repetições. Os tratamentos foram constituídos por seis doses de lodo de esgoto (0, 2,5, 5, 10, 15 e 20 t ha-1), mais um que recebeu a adubação química. A aplicação de lodo de esgoto, para recuperação de áreas degradadas, aumentou os agregados do solo conforme o aumento das doses de lodo, até 12 meses após sua aplicação. As porosidades (macro, micro e total) do solo foram aumentadas com as maiores doses de lodo de esgoto até seis meses após sua aplicação; apenas a microporosidade foi aumentada até 12 meses após a aplicação. Houve aumento da umidade do solo em função do aumento das doses de lodo no solo até seis meses após a aplicação.

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

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Introduction: The SPPB provides information about physical function and is a predictor of adverse events in the elderly. Frailty is a multidimensional syndrome that increases susceptibility to diseases and disability. However it may be possible to prevent or postpone frailty if is identified early. Our objective is to analyze SPPB s ability in screening for frailty a community-dwelling young elderly from cities with distinct socioeconomic conditions. Methods: Data were originated from community dwelling adults (65-74 years old) in Canada (Saint Bruno; n = 60) and Brazil (Santa Cruz; n = 64). SPPB was used to assess physical performance. Frailty was defined as the presence of ≥ 3 of these criteria: weight loss, exhaustion, weakness, mobility limitation and low physical activity. One point was given for each criterion met, totalizing a frailty score ranged from 0 to 5. The Linear Regression and Receiver Operating Characteristics analyses were performed to evaluate the SPPB s screening ability. Results: Mean age was 69.48, 10.0% of the Saint Bruno s sample and 28.1% of Santa Cruz s were frail (p = 0.001), the SPPB score means were 9.6 and 8.5 respectively (p = 0.01). SPPB correlated with the frailty score (R2 = 0.33), with better results for Saint Bruno. A cutoff of 9 in SPPB had good sensitivity and specificity in discriminating frail from non frail in Saint Bruno (AUC = 0.81) but showed fair results in Santa Cruz (AUC = 0.61). Conclusion: The SPPB has moderate ability in predicting frailty among older adult s population, and is an useful test to identify people with good functionality and low frailty when SPPB scores are ≥9

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Objectives To estimate the relationship between family nucleus and sport practice among adolescents.Methods A school-based cross-sectional study carried out with 1,752 Brazilian adolescents (812 male and 940 female), aged 11-17 years. Characteristics of the family nucleus (parental education, socioeconomic status and number of siblings) and sport practice (>= 240 min/week) were assessed by questionnaires. Adjusted prevalence ratios were estimated using Poisson regression models.Results The overall prevalence of sport practice was 14.8% (boys 21.2% and girls 9.4%, P = 0.001). Higher socioeconomic status, number of siblings and parents' educational level were associated with more sport practice.Conclusion Despite the low engagement, family nucleus plays an essential role in the sport practice of our sample of Brazilian adolescents.

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This article analyzes the electrical parameters of a 3-phase transmission line using a 280-m-high steel tower that has been proposed for the Amazon transmission system in Brazil. The height of the line conductors and the distance between them are intrinsically related to the longitudinal and transverse parameters of the line. Hence, an accurate study is carried out in order to show the electrical variations between a transmission line using the new technology and a conventional 3-phase 440-kV line, considering a wide range of frequencies and variable soil resistivity. First, a brief review of the fundamental theory of line parameters is presented. In addition, by using a digital line model, simulations are carried out in the time domain to analyze possible and critical over-voltage transients on the proposed line representation.

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This paper presents an experimental investigation of the characteristics of leak noise in plastic water-filled pipes. An experimental set-up was designed to identify the physical mechanisms of leak noise generation. Possible mechanisms include cavitation and turbulence. The experiments show that cavitation is not responsible for leak noise generation and clearly indicate that turbulence is the main mechanism, at least in the experiments conducted. An alternative experimental set-up was also designed to identify the characteristics of leak noise spectra and to investigate how the spectra are affected by the leak size and the leak flow velocity. A number of different hole sizes (leaks) starting from 1 mm diameter, increasing progressively every 0.5 mm until a size of 4 mm diameter were tested for different jet velocities and an empirical model that describes this behaviour is proposed.

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An investigation was made of the influence of alkaline extraction on the characteristics of humic substances extracted from Brazilian soil samples. Humic substances (HS) from seven different soils samples collected in Brazil were extracted using the procedure recommended by the International Humic Substances Society (IHSS). Soils, HS and humins were characterized by thermogravimetry and differential thermal analysis. About 8 mg of each material (soil, HS and humin) were placed in a platinum crucible and heated continuously from 20 to 750 degrees C at a heating rate of 10 degrees C min(-1) in an atmosphere of synthetic air (100 ml min(-1)). A thermal analysis revealed a difference between the content and structural characteristics of organic matter present in HS and humin fractions in relation to their soils. The results indicated that alkaline extraction alters the characteristics of humic substances during the extraction process, underlining the importance of developing methodologies and analytical procedures that allow organic matter in soils to be studied without extracting it. (c) 2005 Elsevier B.V. All rights reserved.

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The spatial variability of mechanical resistance to penetration (PR) and gravimetric moisture (GM) was studied at a depth of 0-0.40 m, in a ferralsol cropped with corn, and under conventional tillage in llha Solteira, Brazil (latitude 20 degrees 17'S, and longitude 52 degrees 25'W). The purpose of this study was to analyse and to try explaining the spatial variability of the mentioned soil physical properties using geostatistics. Soil data was collected at points arranged on the nodes of a mesh with 97 points. Geostatistics was used to analyse the spatial variability of PR and GM at four depths: 0-0. 1, 0.1-0.2, 0.2-0.3 and 0.3-0.4 m. PR showed a higher variability of data, with coefficients of variation of 52.39, 30.54, 16.91, and 15.18%, from the surface layers to the deepest layers. The values of the coefficients of variation for GM were lower: 9.99, 5.13, 5.59, and 5.69%. Correlation between GM and PR for the same soil layers was low. Penetration resistance showed spatial structure only in the 0.30-0.40 m layer, while gravimetric moisture showed spatial structure at all depths except for 0-0. 10 m. All the models of fitted semivariograms were spherical and exponential, with ranges of 10-80 m. Data for the variable 'GM' in the 0.20-0.30 and 0.30-0.40 m layers revealed a trend in data attributed to the occurrence of subsurface water flow. (C) 2005 Elsevier B.V. All rights reserved.

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Este trabalho teve por objetivo estudar os efeitos de diferentes sistemas de uso e manejo na densidade do solo nas suas propriedades químicas e na atividade microbiana em um Latossolo Vermelho distrófico (Oxisol). As amostras de solo foram retiradas de parcelas dos seguintes tratamentos: cerrado denso preservado, pastagem de Brachiaria decumbens degradada (20 anos), plantio direto com rotação de culturas (8 anos) e sistema convencional com rotação de culturas anuais (10 anos). O delineamento experimental utilizado foi o inteiramente casualizado, com dez repetições. O uso contínuo de plantio direto resultou em mais alta taxa de C-biomassa microbiana e menor perda relativa de carbono pela respiração basal, podendo determinar, desta forma, maior acúmulo de C no solo a longo prazo. Proporcionou, ainda, melhoria na densidade aparente e nas propriedades químicas do solo. Assim, o sistema plantio direto, com manejo de culturas, mostrou ser uma alternativa para a conservação e manutenção das condições físicas e do potencial produtivo de solos de cerrado.

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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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As pastagens cultivadas do Cerrado brasileiro são responsáveis pela metade da produtividade da carne bovina destinada à alimentação da população, enquanto as culturas agrícolas o são pela terça parte de sua produtividade de grãos, desempenhando importante papel econômico-financeiro para o país. Dessa forma, no ano agrícola 2005/2006, na Fazenda de Ensino e Pesquisa da Faculdade de Engenharia de Ilha Solteira - FEIS/UNESP, foram estudadas a variabilidade e a dependência espacial entre atributos físicos do solo e a produtividade da soja, quando rotacionados após a pastagem degradada com Brachiaria, sobre um Latossolo Vermelho distroférrico. Também foram estudadas correlações lineares e espaciais entre esses atributos, apurando condições que proporcionassem aumento da produtividade agrícola. Para isso, na área com a referida pastagem instalou-se uma malha contendo 124 pontos amostrais, com espaçamentos de 10,0 x 10,0 e de 5,0 x 5,0 m entre eles, numa área total de 7.500 m². Dos pontos de vista linear e espacial, a elevada produtividade de grãos de soja pode ser explicada em razão do número de grãos por planta e da macroporosidade do solo. A alta variabilidade obtida na maioria dos atributos do solo denotou que a integração lavoura-pecuária é um sistema que proporciona heterogeneidade do ambiente físico do solo.

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The present review is a critical analysis of positive and negative reports of the isolation of Paracoccidioides brasiliensis from soil. The strains isolated from soil or soil-contaminated material (dogfood, penguin feces) by Batista et al. in Recife, Brazil, Negroni in the Argentinian Chaco, Albornoz in rural Venezuela, Silva-Vergara et al, in Ibia, Brazil, Ferreira et al, in Uberlandia, Brazil, and Gezuele et al. at the Uruguayan base in the Antarctic region, presented mycological characteristics consistent with P. brasiliensis. In most of these studies, morphological characterization was complemented with an evaluation of virulence and antigenicity, and biochemical or molecular analysis. These isolations, therefore, can be considered true, supporting the concept of soil as an important element in the ecology of the pathogen. The large number of negative reports in attempts involving soil samples and the low repeatability of isolation of the fungus from the same area indicate that the specific conditions supporting growth of the pathogen in soil have not been fully clarified.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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