23 resultados para relações fonte-dreno

em Repositório da Produção Científica e Intelectual da Unicamp


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Seasonal variation in environmental conditions may influence gas exchange rates as well as water relations in perennial species. This work was carried out to evaluate photosynthetic rates (A), transpiration (E), stomatal conductance (g) and leaf water potential (psi f ) in 'Valencia' orange trees grafted on four different rootstocks. Measurements were made twice a day: from 9h00 to 11h00 a.m. and from 1h00 to 3h00 p.m., during January, March and July. A and g were significantly lower and psif was significantly more negative, in the afternoon. The decrease in A may be related to the reduction in g, due to the increase in the vapor pressure deficit between the air and the leaf (VPDair-leaf ) in the afternoon, when temperatures are higher. In spite of the partial stomatal closure in the afternoon, the values for E were approximately the same as those measured in the morning, due to the increase in the VPDair-leaf . A decrease in A and g could also be noted from January to July, that is, from the hot and humid summer months, to the colder and drier winter ones. It was suggested that the decrease in A and g observed from January through March, may be related to the decrease in plant growth rates, which could have influenced the source-sink relationships, since the climatic conditions for both months were similar. The decrease in A and g showed in July, seems to be related to the decrease in both the night temperature and the growth rate of plants.

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This article describes the use of a conventional CRT monitor as a high voltage power supply for capillary electrophoresis. With this monitor, a 23-kV high voltage with a ripple of 1.32% was observed. The reproducibility of the applied high voltage was evaluated by measuring the standard deviations of peak area and migration time for five consecutive injections of a test mixture containing potassium, sodium, and lithium cations at 50 mmol L-1. The errors were about 2.5% and 0.6% for peak area and migration time, respectively. The maximum current tested was about 180 mA, which covers most capillary electrophoresis applications. This system has been successfully used for several months, maintaining the desired level of performance.

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This survey aimed at describing the interactions of floral visitors and Davilla kunthii A. St.-Hil. as well as characteristics of its reproductive biology in Itacoatiara, state of Amazonas, Brazil. Tests of the breeding system were performed. The guild of visitors was described according to richness, abundance, relative frequency and constancy. The breeding system tests indicated that D. kunthii is self-compatible. The pollination system was characterized as generalist, with 39 visitor species, from three different orders. Bees were the main group of pollinators, thus some behavioural aspects were described. Th e period of highest foraging activity was between 7 and 10 am. Some species presented agonistic and monopolistic behaviour. Given the behaviour and destructive potential, the Curculionidae seem to have a greater impact as seed predators than pollinators.

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Behavioral adaptiveness to different situations as well as behavioral individuality result from the interrelations between environmental sitmuli and the responses of an organism.These kind of interrelationships also shape the neural circuits as well as characterize the plasticity and the neural individuality of the organism. Studies on neural plasticity may analyze changes in neural circuitry after environmental manipulations or changes in behavior after lesions in the nervous system. Issues on neural plasticity and recovery of function refer both to physiology and behavior as well as to the subjacent mechanisms related to morphology, biochemistry and genetics. They may be approached at the systemic, behavioral, cellular and molecular levels. This work intends to characterize these kinds of studies pointing to their relations with the analyis of behavior and learning.The analysis of how the environmental-organismic interrelationships affect the neural substrates of behavior is pointed as a very stimulating area for investigation.

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In this article my main objective is to approach some questions related to the tests used in psychodiagnostics processes of children who are considered as having learning difficulties. Having the book Discipline and Punish (1975/1986) by Foucault as theoretical basis, I intend to investigate the hypothesis that the child is considered ill or abnormal due to the factors related to imposed norms and not to organic aspects and/or neurological pathology. My interest is to analyse the signs that allow us to point out the written language conception of tests. This language is expected and privileged, however it may not be the language that the child uses and experiences every day.

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Universidade Estadual de Campinas . Faculdade de Educação Física

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Universidade Estadual de Campinas . Faculdade de Educação Física

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Universidade Estadual de Campinas . Faculdade de Educação Física

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Universidade Estadual de Campinas . Faculdade de Educação Física

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Universidade Estadual de Campinas. Faculdade de Educação Física

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Universidade Estadual de Campinas . Faculdade de Educação Física

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Universidade Estadual de Campinas . Faculdade de Educação Física

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Universidade Estadual de Campinas . Faculdade de Educação Física