104 resultados para modelo quadrático com resposta em platô


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Pós-graduação em Engenharia e Ciência de Alimentos - IBILCE

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Germination parameters of the response to temperature and water potential from four common bean (Phaseolus vulgaris) lines based on thermal-time and hydrotime concepts were estimated to verify to what extent they can predict germination under different thermal and water conditions. The cultivars IPR Uirapuru and IAPAR 81 (drought-tolerant), and Grauna and Carioca (not tolerant) were used. The isothermal assays were performed in a temperature gradient block, and the assays with different osmotic potentials (PEG 6000) were performed in germination chambers. Seeds from drought-tolerant cultivars spent less time to germinate at supra-optimum temperatures than non-tolerant ones, and the cultivar Uirapuru (drought-tolerant) germinated faster in response to reduced Ψ and low temperatures. The parameter Ψb(50) did not discriminate between drought-tolerant and non-tolerant lines at the infraoptimum temperature range, but it can be used to identify drought-tolerant lines at high temperatures. In general, the hydrotime model reproduced the actual germination data relatively well, chiefly at higher temperatures. This study evidenced that the hydrotime model can be used to describe the germination of common bean seeds under reduced water potentials, and as a screening tool for drought-tolerant bean genotypes.

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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)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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This paper proposed a two-dimensional spatial model to describe the adaptive immune response for viral hepatitis B. This model considered six populations: healthy hepatocytes T, infected hepatocytes Y , hepatitis B virus V , innate immune system I, active immune system X and memory cells, X. First, a compartmental model was constructed and its equilibrium solutions and also the threshold values related to the stability of each solution were obtained. Using this model, we was able to reproduce the different trends observed for the disease, which are: individuals that eliminate the infection without forming immune response, patients with acute and chronic carriers. By including dispersion of defense cells of the immune system and virus (spatial model), we analyze two situations: homogeneous model, in which the model parameters are the same at all points of the network, and heterogeneous model, which characterizes cells more permeable and less permeable to virus invasion. For the two spatial models (homogeneous and heterogeneous) the times relatead to the viral erradication and/or virus invasion and persistence becoming smaller in relation to the compartmental model. The results also showed that for the set of values used in the simulations and if the two diffusion rates are different from zero, the model is sensitive to variations in the rate of viral spread and not dependent on the dispersion of memory cells. Finally, the heterogeneous model when compared to the homogeneous model shows that the infection can be spatially limited depending on the type of the cell involved in the infection process

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Pós-graduação em Biociências e Biotecnologia Aplicadas à Farmácia - FCFAR

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Pós-graduação em Zootecnia - FCAV

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The aim of this research study was to evaluate the structural behaviour of the wood and concrete composite system for bridge decks with emphasis on the metal shear connectors. Experimental tests were performed on composite specimens and wood and concrete beams with a metallic connector system in an X position, using CS100900-type screws. All specimens and beams were submitted to static loads until failure in order to obtain the strength and stiffness of the connection system. The experimental results for the stiffness of the beams were compared with the analytical results obtained through the Mohler model, presenting good equivalence for service loads. The experimental results obtained demonstrate that the most significant damage in composite systems occurred in the connectors' areas.

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Foram avaliados em condições de campo, em solo arenoso, com baixo teor de boro, os efeitos da adubação com cinco doses de boro (0; 2; 4; 6 e 8 kg ha-1 de B na forma de bórax) na produção de brócolis, couve-flor e repolho. O experimento obedeceu a um esquema fatorial com delineamento experimental de blocos ao acaso com três repetições. As adubações orgânica e química, inclusive o bórax, foram feitas no sulco antes do transplantio das mudas e a colheita foi feita entre 63 e 93 dias após o transplantio. A produtividade de brócolis variou de 16,9 a 20,5 t ha-1; a de couve-flor de 21,6 a 29,6 t ha-1 e a de repolho de 40,5 a 46,4 t ha-1. O aumento observado na produtividade de brócolis e de repolho foi linear e o efeito das doses de boro na produtividade de couve-flor foi quadrático, sendo necessários 5,1 kg ha-1 de B para atingir a produtividade máxima de 30 t ha-1. Brócolis e repolho mostraram-se menos sensíveis do que a couve-flor tanto à deficiência quanto ao excesso de boro. No caso da couve-flor, com a aplicação de 2 kg ha-1 ou de 6 kg ha-1 de B houve significativa perda de qualidade do produto.