Alternate islands of multiple isochronous chains in wave-particle interactions

We analyze the dynamics of a relativistic particle moving in a uniform magnetic field and perturbed by a standing electrostatic wave. We show that a pulsed wave produces an infinite number of perturbative terms with the same winding number, which may generate islands in the same region of phase space. As a consequence, the number of isochronous island chains varies as a function of the wave parameters. We observe that in all the resonances, the number of chains is related to the amplitude of the various resonant terms. We determine analytically the position of the periodic points and the number of island chains as a function of the wave number and wave period. Such information is very important when one is concerned with regular particle acceleration, since it is necessary to adjust the initial conditions of the particle to obtain the maximum acceleration.Comment: Submitte

Use of Physical Education Classes as a Didactic Laboratory for Teaching Mathematics: An Example with a Quadratic Function

The research objective of this study was to evaluate the use of Physical Education classes as didactic laboratory for lessons in Mathematics, presenting an alternative way to conduct classes, mainly of quadratic functions, illustrating basic concepts such as graphs plotting and determination coefficients, analyze if such use achieves some of the goals of using a Didactic Laboratory in addition to research ways to interdisciplinary with Physics. Discusses an action in which students work in groups to solve problems proposed based on empirical data obtained through play activities and measures of athletics values practiced by the students allowing may have the opportunity to produce arguments and more meaningful answers, which would improve the overall learning. The athletics and recreational activities are then used as problematic objects both empirically and qualitatively. As a result, it was observed that some of the objectives of a Didactic Laboratory are achieved when using the Physical Education classes and it appears that this feature is much more available in public schools than they are equipped with a science laboratory

Proposta metodológica para avaliação da efetividade das políticas sociais para agricultores familiares do Estado de Goiás.

O objetivo principal desse artigo é realizar uma revisão bibliográfica e uma proposta metodológica para avaliar as efetividades sociais das políticas públicas para os agricultores familiares do estado de Goiás. Os programas escolhidos pelas suas representatividades sociais e econômicas para o campo e especificamente para a agricultura familiar, sujeito deste trabalho, são o Programa Nacional da Alimentação Escolar (PNAE), o Programas de Aquisição de Alimentos (PAA) da Agricultura Familiar. Também será abordado o Programa Bolsa Família, que não se trata da temática da segurança alimentar, mas que é um programa social de grande inserção no meio rural, especificamente para os agricultores familiares, e com a hipótese que tem efeitos significativos em elementos de segurança alimentar dos agricultores familiares do território em questão

Cultivares de soja para a microrregião de Paragominas, Pará.

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Modelagem da paisagem no Parque Estadual Carlos Botelho (SP) e entorno.

The aim of this study was to model landscape change in a nature conservation area located in the Atlantic Forest within São Paulo State, Brazil, called Carlos Botelho State Park ? CBSP, and also in its surroundings, both currently under anthropogenic pressure. A cellular automata stochastic simulation platform - Dinamica EGO ? was used, which embodies neighborhood-based transition algorithms and the weights of evidence method as a parameterization approach. Water bodies, forest, agriculture, and forestry (eucalyptus) were considered as land cover categories in this model. Variables like distance to roads and distance to existent types of land cover in the area were crucial to explain the observed landscape changes. The prevailing conversion of land-use/land-cover was agriculture to eucalyptus. There were no findings of significant increase of human pressure in CBSP, except in a small stretch in the northwest of the Park. There is evidence that the establishment of a nature conservation area in the eastern sector of CBSP might be feasible, since it would strengthen an ecological corridor towards the Jurupará Park. Fiscalization and routine monitoring should be strictly observed, considering that the CBSP may suffer greater pressure of the eucalyptus plantations that increasingly expand into surrounding the region analyzed. To improve this research, more variables should be investigated, for example, the role the role of distance to suppliers / markets and roads, soil categories, as well as socioeconomic factors through coupled models of dynamic systems

Factors controlling spatio-temporal variation in carbon dioxide efflux from surface litter, roots, and soil organic matter at four rain forest sites in the eastern Amazon

[1] This study explored biotic and abiotic causes for spatio-temporal variation in soil respiration from surface litter, roots, and soil organic matter over one year at four rain forest sites with different vegetation structures and soil types in the eastern Amazon, Brazil. Estimated mean annual soil respiration varied between 13-17 t C ha(-1) yr(-1), which was partitioned into 0-2 t C ha(-1) yr(-1) from litter, 6-9 t C ha(-1) yr(-1) from roots, and 5-6 t C ha(-1) yr(-1) from soil organic matter. Litter contribution showed no clear seasonal change, though experimental precipitation exclusion over a one-hectare area was associated with a ten-fold reduction in litter respiration relative to unmodified sites. The estimated mean contribution of soil organic matter respiration fell from 49% during the wet season to 32% in the dry season, while root respiration contribution increased from 42% in the wet season to 61% during the dry season. Spatial variation in respiration from soil, litter, roots, and soil organic matter was not explained by volumetric soil moisture or temperature. Instead, spatial heterogeneity in litter and root mass accounted for 44% of observed spatial variation in soil respiration (p < 0.001). In particular, variation in litter respiration per unit mass and root mass accounted for much of the observed variation in respiration from litter and roots, respectively, and hence total soil respiration. This information about patterns of, and underlying controls on, respiration from different soil components should assist attempts to accurately model soil carbon dioxide fluxes over space and time