Lobatto deferred correction for stiff two-point boundary value problems

An iterated deferred correction algorithm based on Lobatto Runge-Kutta formulae is developed for the efficient numerical solution of nonlinear stiff two-point boundary value problems. An analysis of the stability properties of general deferred correction schemes which are based on implicit Runge-Kutta methods is given and results which are analogous to those obtained for initial value problems are derived. A revised definition of symmetry is presented and this ensures that each deferred correction produces an optimal increase in order. Finally, some numerical results are given to demonstrate the superior performance of Lobatto formulae compared with mono-implicit formulae on stiff two-point boundary value problems. (C) 1998 Elsevier B.V. Ltd. All rights reserved.

Iterated deferred correction for linear two-point boundary value problems

An analysis of iterated deferred correction based on various classes of implicit Runge-Kutta formulae is given. Out of different possibilities considered, it is shown that those based purely on Lobatto formulae have the best stability. The enhanced stability of Lobatto schemes is very important for the efficient integration of excessively stiff boundary value problems and this is demonstrated by means of some numerical results.

A relação ironia/oralidade em L'imitation de Notre-Dame la lun, de Jules Laforgue

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Initial height of pasture deferred and utilized in winter and tillering dynamics of signal grass during the following spring

Tillering dynamics during regrowth in the spring (September to December 2009) on signal grass (Brachiaria decumbens cv. Basilisk) pastures deferred in the beginning of April 2009 is evaluated. Four pasture heights were evaluated at the beginning of deferment (10, 20, 30 and 40 cm). The experimental design consisted of completely randomized blocks with two replications. Rise in pasture height at the beginning of deferment decreased the appearance rate, increased the mortality rate and reduced the survival rate, the balance between appearance and mortality and the stability index of the tiller population at the beginning of the spring. Pastures deferred at initial height of 30 and 40 cm presented relatively stable tiller appearance rate between the beginning and end of spring. However, these pastures presented greater mortality rate, lower survival rate, lower balance between appearance and mortality and lower stability index of the tiller population at the beginning of spring when compared to rates at the end of spring. Pastures managed with shorter initial heights (10 and 20 cm) provided more tissue renewal in the subsequent growth season after their utilization in the winter.

CONTRIBUTION OF BASAL AND AERIAL TILLERS IN DYNAMICS OF HERBAGE PRODUCTION OF SIGNALGRASS AFTER GRAZING DEFERRED

During the spring, the understanding of regrowth in basal and aerial tillers of deferred pasture in winter it is necessary. Thus, the objective was to evaluate the morphogenesis and herbage accumulation during spring in Brachiaria decumbens cv. Basilisk (signalgrass) pasture used under deferred grazing in winter. The basal and aerial tillers in same pasture were evaluated. The signalgrass was managed with grazing cattle and with an average height of 25 cm. The randomized block design with three replications was adopted. The leaf appearance rate, phyllochron and the numbers of expanded, expanding and live leaves did not differ between basal and aerial tillers. The aerial tiller possessed lower rates of leaf senescence, of leaf elongation and of stem elongation, as well as lower number of dead leaf and stem and leaf lamina lengths, compared to basal tiller. The leaf lifespan was higher in aerial tillers than at basal. The basal tiller also contributed to higher rates of tissue growth and forage accumulation in pasture when compared to aerial tiller. After deferred grazing during the spring, the aerial tiller has low participation in forage production of signalgrass pasture.

Alterações dos processos fonológicos e índice de gravidade entre escolares com dislexia e escolares com bom desempenho acadêmico

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

Educação científica e atividade grupal na perspectiva sócio-histórica

Este trabalho apresenta questões relativas à educação científica e à atividade grupal ou coletiva, na perspectiva da abordagem sócio-histórica do desenvolvimento humano e do ensino científico presente nas obras dos russos L.S. Vigotski e A.N. Leontiev. Fundamentalmente, buscaremos estabelecer essa relação a partir da proposta de Zona de Desenvolvimento Próximo realizada por Vigotski, em que o autor enfatiza o papel da imitação e da cooperação no alcance de novos níveis de desenvolvimento, processo subsidiado pela instrução, tendo como mediação o educador.

Ciclos clássicos num ambiente de racionalidade limitada

O presente trabalho toma como ponto de partida o modelo macrodinâmico de Richard M. Goodwin, apresentado no clássico artigo A Growth Cycle (1967). Neste modelo a interação entre distribuição de renda e acumulação de capital gera um ciclo de crescimento que oscila em torno de uma trajetória de crescimento equilibrado. O objetivo do presente trabalho é investigar a possibilidade de existência de ciclos goodwinianos com heterogeneidade de salários e de taxas de lucro. Essa análise é realizada considerando o processo de concorrência entre trabalhadores num ambiente de racionalidade limitada. Para formalizar o processo de concorrência entre trabalhadores foram utilizados dois recursos: (i) a alegoria das ilhas , que tem sido amplamente adotada na macroeconomia moderna, a fim de apreender situações de informação imperfeita; e (ii) os instrumentos analíticos desenvolvidos pela teoria dos jogos evolucionários aplicada a ambientes sociais. O modelo construído combina o modelo de Goodwin com uma formalização estilizada do fluxo de trabalho como um processo de imitação num ambiente de racionalidade limitada (dinâmica de replicação num contexto social). Neste modelo demonstra-se a possibilidade de o sistema econômico não convergir para um estado de equilíbrio de longo prazo e a possibilidade do sistema econômico convergir para um ciclo goodwiniano caracterizado por heterogeneidade de salários e de taxas de lucro.

Função motora fina de escolares com dislexia, distúrbio e dificuldades de aprendizagem

TEMA: função motora fina em escolares com dislexia, distúrbio e dificuldades de aprendizagem. OBJETIVO: este estudo teve por objetivo caracterizar o desempenho da função motora fina, sensorial e perceptiva em escolares com dislexia, distúrbio e dificuldades de aprendizagem e correlacionar estes achados à escrita destes escolares. MÉTODO: participaram deste estudo 80 escolares da 2ª à 4ª série do ensino fundamental, na faixa etária de 7 a 12 anos de idade, de ambos os gêneros, distribuídos em: GI: formado por 20 escolares com dislexia, GII: formado por 20 escolares com distúrbio de aprendizagem, GIII: formado por 20 escolares com dificuldades de aprendizagem e GIV: formado por 20 escolares sem dificuldades de aprendizagem. Os escolares foram submetidos à avaliação da função motora fina, sensorial e perceptiva e análise da escrita por meio da escala de disgrafia. RESULTADOS: os resultados evidenciaram que a maioria dos grupos apresentou desempenho inferior nas provas de FMF7 (oposição de dedos), S8 (grafoestesia) e P1 (imitar posturas). Os GI e GII foram os grupos que apresentaram desempenho inferior na maioria das provas em relação aos GIII e GIV. Quanto à grafia, observou-se que no GII todos os escolares são disgráficos. CONCLUSÃO: a presença de alterações motora fina, sensorial e perceptiva é característica de escolares com distúrbio de aprendizagem e dislexia, entretanto esta característica pode ou não ser encontrada nos escolares com dificuldades de aprendizagem, sendo, portanto, esta alteração responsável pelo comportamento disgráfico dos escolares com transtornos de aprendizagem deste estudo.

Bacteriocin-like substances production by Streptococcus-salivarius against oral bacteria

Samples of tongue and bucal mucosa surfaces were obtained from six healthy subjects with the purpose of isolating S. salivarius. It was verified that 47 out of 48 S. salivarius strains produced bacteriocin-like substances against at least one of the indicator species: Actinomyces viscosus, Rothia dentocariosa, Streptococcus pyogenes, Staphylococcus aureus, Streptococcus mutans and Streptococcus sanguis. The method employed to test for bacteriocin production was that of deferred antagonism. The results showed that there was a high antagonism against R. dentocariosa, S. pyogenes and A. viscosus; extremely low against S. mutans and S. sanguis and no inhibition for S. aureus.

A Harris-Todaro agent-based model to rural-urban migration

The Harris-Todaro model of the rural-urban migration process is revisited under an agent-based approach. The migration of the workers is interpreted as a process of social learning by imitation, formalized by a computational model. By simulating this model, we observe a transitional dynamics with continuous growth of the urban fraction of overall population toward an equilibrium. Such an equilibrium is characterized by stabilization of rural-urban expected wages differential (generalized Harris-Todaro equilibrium condition), urban concentration and urban unemployment. These classic results obtained originally by Harris and Todaro are emergent properties of our model.

Estrutura do capim-braquiária durante o diferimento da pastagem

This experiment was performed aiming to evaluate tiller population density, forage mass and its morphological components on pastures of Brachiaria decumbens cv. Basilisk. during deferment. The treatments encompassed four deferred grazing periods (18, 46, 74 and 121 days). A randomized block design with two replications was used. The numbers of vegetative tillers (VT), reproductive tillers (RT) and dead tillers (DT) in the pasture were determined. The masses of green leaf blade (GLBM), dead stem (DSM) and dead forage (DFM) were also determined. There was a reduction in the number of VT (from 1, 491 to 944 tiller m-2) during the deferment period. RT and DT numbers were not influenced by the deferment periods. Their averages were 211 and 456 tiller m-2, respectively. Longer deferring periods resulted in an increase in GSM (from 2, 965 to 4, 877 kg ha-1 of dry mass) and DFM (from 2, 324 to 4, 823 kg ha-1 of dry mass), but it did not influence GLBM (average of 2, 047 kg ha-1 of dry mass). In Viçosa, Minas Gerais State Brazil, Brachiaria decumbens cv. Basilisk pasture fertilized and deferred in the beginning of March must be kept deferred for about 70 days in order to conciliate both quality and quantity forage production.

Faces de Marília: a moradia em um condomínio horizontal

Pós-graduação em Ciências Sociais - FFC

Consciência e atividade: um estudo sobre (e para) a infância

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)