185 resultados para Hill Equation

em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"


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We consider the problem of stability and duration of the synchronization process between self-excited oscillators, both in their regular and chaotic states. Making use of the properties of Hill equation describing the deviation between the slave and the master, we derive the stability conditions and expressions of the synchronization time. A fairly good agreement is obtained between the analytical and numerical results.

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In this paper we show how to obtain efficient designs of experiments for fitting Michaelis-Menten and Hill equations useful in chemical studies. The search of exact D-optimal designs by using local and pseudo-Bayesian approaches is considered. Optimal designs were compared to those commonly used in practice using an efficiency measure and theoretical standard errors of the kinetic parameter estimates. In conclusion, the D-optimal designs based on the Hill equation proved efficient for estimating the parameters of both models. Furthermore, these are promising with respect to practical issues, allowing efficient estimation as well as goodness-of-fit tests and comparisons between some kinetic models.

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The Hill's equations-even in the linear original version are a describer of phenomenon having chaotic flavor, giving sometimes very unusual situations. The theory of the so called intervals of instability in the equation provides the precise description for most of these phenomena. Considerations on nonlinearities into the Hill's equation is a quite recent task. The linearized version for almost of these systems it reduces to the Hill's classical linear one. In this paper, some indicative facts are pointed out on the possibility of having the linear system stabilizable and/or exactly controllable. As consequence of such an approach we get results having strong classical aspects, like the one talking about location of parameters in intervals of stability. A result for nonlinear proper periodic controls, is considered too. (C) 2010 Elsevier B.V. All rights reserved.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The predators were collected in mate crop in Cascavel and São Mateus do Sul, Paraná, Brazil and some other additional specimens in coffee and maize crops in Ribeirão Preto, São Paulo, Brazil. Illustrations obtained by SEM are given by the first time to the principal structures. Three species of Hemerobius were identified: H. bolivari Banks, 1910; H. domingensis Banks, 1941 and H. gaitoi Monserrat, 1996. H. domingensis is recorded for the first time to Brazil.

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The objectives of the study were to assess changes in fine root anisotropy and specific root lengths throughout the development of Eucalyptus grandis ( W. Hill ex Maiden) plantations and to establish a predictive model of root length density (RLD) from root intercept counts on trench walls. Fine root densities (<1 mm in diameter) were studied in 6-, 12-, 22-, 28-, 54-, 68- and 72-month-old E. grandis plantations established on deep Ferralsols in southern Brazil. Fine root intercepts were counted on 3 faces of 90-198 soil cubes (1 dm(3) in volume) in each stand and fine root lengths (L) were measured inside 576 soil cubes, sampled between the depths of 10 cm and 290 cm. The number of fine root intercepts was counted on one vertical face perpendicular to the planting row (N(t)), one vertical face parallel to the planting row (N(l)) and one horizontal face (N(h)), for each soil cube sampled. An overall isotropy of fine roots was shown by paired Student's t-tests between the numbers of fine roots intersecting each face of soil cubes at most stand ages and soil depths. Specific root lengths decreased with stand age in the upper soil layers and tended to increase in deep soil layers at the end of the rotation. A linear regression established between N(t) and L for all the soil cubes sampled accounted for 36% of the variability of L. Such a regression computed for mean Nt and L values at each sampling depth and stand age explained only 55% of the variability, as a result of large differences in the relationship between L and Nt depending on stand productivity. The equation RLD=1.89*LAI*N(t), where LAI was the stand leaf area index (m(2) m(-2)) and Nt was expressed as the number of root intercepts per cm(2), made it possible to predict accurately (R(2)=0.84) and without bias the mean RLDs (cm cm(-3)) per depth in each stand, for the whole data set of 576 soil cubes sampled between 2 years of age and the end of the rotation.

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The components used in the production of substrates influence directly the growth cycle, quality and consequently the cost of production of seedlings. In this experiment we studied the development, quality and cost of Eucalyptus grandis Hill ex Maiden x E. urophylla S. T. Blake, through sexual propagation using 12 compositions of substrate. The results showed that the pure substrates, with the exception of coconut fiber, did not present physical characteristics appropriate for the production from seedlings of eucalyptus in container, with the best results obtained for the substrates with a mixture 1:1 of carbonized rid of rice and coconut-fiber and a mixture 1:1 of vermiculite and coconut fiber, due to the best morphological characteristics and the possibility of reducing the production period which enables a reduction in the cost of final seedling.

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The juvenile wood presents great difference in its anatomical and physical properties in relation to the mature wood. That heterogeneity of the wood causes a series of upset for the processing industry. The present research had as objective the study of the physical properties of the juvenile and mature wood of Pinus elliottii Engelm var. elliottii, with 25 years of age and of Eucalyptus grandis Hill ex Maiden, with 30 years of age, coming from the Experimental Station of Itapetininga and State Forest of Santa Barbara, belonging to the Forest Institute of the state of São Paulo. From both species there were taken from radial boards, specimens with dimensions of 20x30x50 mm, for the determination of density, swelling and swelling coefficient of the juvenile and mature wood. The results of the species showed that the mature compared with the juvenile wood presented: (1) an increase in the values of the basic density, at 0% and at 12% of moisture content and of the volumetric, radial and tangential swelling at 12% moisture content and maximum coefficient of radial and tangential swelling; (2) a reduction in the values of longitudinal swelling at 12% and maximum and of the longitudinal swelling coefficient.

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Este estudo visou avaliar a variabilidade e distância genética dentro de uma população-base de melhoramento genético de Eucalyptus grandis. A avaliação da variabilidade genética tem como objetivos principais analisar a base genética da população-base e montar um banco de dados marcadores moleculares da população em análise. Essa população é formada por 327 indivíduos, principalmente das procedências de Coff's Harbour, Atherton e Rio Claro. Devido à heterozigosidade natural dessa população, ela pode ser dividida em diversas subpopulações, de acordo com a latitude e longitude de origem; e dentro de subpopulações, em função do grau de melhoramento genético já realizado do material analisado no Brasil. Isso permitiu avaliar quanto da variabilidade detectada dentro da população-base foi devido a esses fatores: procedência e grau de melhoramento. A aplicação da técnica RAPD permitiu avaliar 70 locos polimórficos, que foram analisados utilizando-se o coeficiente de Jaccard, o que resultou em matrizes de similaridade genética entre os indivíduos. Os dados de similaridade genética posteriormente foram submetidos à análise estatística. Osdados indicaram que a população-base apresenta ampla base genética, com média de similaridade genética de 0,328. O subgrupo denominado Região 3, composto por material selvagem da macrorregião de Atherton, juntamente com material de APS da macrorregião de Coff's Harbour, foi um dos que mais contribuíram para a ampla base genética da população-base. Foi possível detectar diferença estatística entre as populações selvagens das procedências de Atherton e Coff's Harbour, assim como entre essas procedências e a de Rio Claro.

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