10,635 research outputs found

    Vulnerabilidade do patrimônio ambiental tombado em Campinas-SP e sua relação com índice de vegetação.

    Get PDF
    Research conducted in forest fragments have contributed to the development of models for recovery of degraded areas, generating decrease deployment costs with increased efficiency, helping in forest management studies, and effectively preserving the remaining vegetation when considering the dynamics of regeneration compared to patterns of space occupation. The survey of the occupation history for the surrounding urban forest fragments located in the city of Campinas, São Paulo, Brazil, structured in a Geographical Information System (GIS), allowed to establish a classification which indicates the degree of vulnerability of these forests remnants based on the degree of deterioration of the landscape caused by the incidence of certain activities. The survey was made using legal decisions, occupation history, fauna and flora surveys, environmental reports, information on plant and animal biodiversity as well as the physical characteristics of the fragment?s area, which exemplified the degree and pattern of human occupation. The extraction of the Normalized Difference Vegetation Index (NDVI) for each area allowed to establish a relation between the occupation pattern for the surrounding and the changes in vegetation cover within these forests fragments, which presented a good match with the degree of vulnerability attributed in previous step

    Local Physical Coodinates from Symplectic Projector Method

    Get PDF
    The basic arguments underlying the symplectic projector method are presented. By this method, local free coordinates on the constrait surface can be obtained for a broader class of constrained systems. Some interesting examples are analyzed.Comment: 8 page

    Renormalization of the N=1 Abelian Super-Chern-Simons Theory Coupled to Parity-Preserving Matter

    Full text link
    We analyse the renormalizability of an Abelian N=1 super-Chern-Simons model coupled to parity-preserving matter on the light of the regularization independent algebraic method. The model shows to be stable under radiative corrections and to be gauge anomaly free.Comment: Latex, 7 pages, no figure

    Future dynamics in f(R) theories

    Full text link
    The f(R)f(R) gravity theories provide an alternative way to explain the current cosmic acceleration without invoking dark energy matter component. However, the freedom in the choice of the functional forms of f(R)f(R) gives rise to the problem of how to constrain and break the degeneracy among these gravity theories on theoretical and/or observational grounds. In this paper to proceed further with the investigation on the potentialities, difficulties and limitations of f(R)f(R) gravity, we examine the question as to whether the future dynamics can be used to break the degeneracy between f(R)f(R) gravity theories by investigating the future dynamics of spatially homogeneous and isotropic dust flat models in two f(R)f(R) gravity theories, namely the well known f(R)=R+αRnf(R) = R + \alpha R^{n} gravity and another by A. Aviles et al., whose motivation comes from the cosmographic approach to f(R)f(R) gravity. To this end we perform a detailed numerical study of the future dynamic of these flat model in these theories taking into account the recent constraints on the cosmological parameters made by the Planck team. We show that besides being powerful for discriminating between f(R)f(R) gravity theories, the future dynamics technique can also be used to determine the fate of the Universe in the framework of these f(R)f(R) gravity theories. Moreover, there emerges from our numerical analysis that if we do not invoke a dark energy component with equation-of-state parameter ω<1\omega < -1 one still has dust flat FLRW solution with a big rip, if gravity deviates from general relativity via f(R)=R+αRnf(R) = R + \alpha R^n . We also show that FLRW dust solutions with f<0f''<0 do not necessarily lead to singularity.Comment: 12 pages, 8 figures. V2: Generality and implications of the results are emphasized, connection with the recent literature improved, typos corrected, references adde

    Sistemas de produção em policultivo de mandioca, milho e caupi para a microrregião Bragantina-Pará.

    Get PDF
    bitstream/item/33619/1/CPATU-CirTec4.pd

    Teleparallel Equivalent of Non-Abelian Kaluza-Klein Theory

    Get PDF
    Based on the equivalence between a gauge theory for the translation group and general relativity, a teleparallel version of the non-abelian Kaluza-Klein theory is constructed. In this theory, only the fiber-space turns out to be higher-dimensional, spacetime being kept always four-dimensional. The resulting model is a gauge theory that unifies, in the Kaluza-Klein sense, gravitational and gauge fields. In contrast to the ordinary Kaluza-Klein models, this theory defines a natural length-scale for the compact sub-manifold of the fiber space, which is shown to be of the order of the Planck length.Comment: Revtex4, 7 pages, no figures, to appear in Phys. Rev.
    corecore