5,107 research outputs found

    Spatial patterns of Qualea grandiflora in cerrado fragments in Sao Paulo state

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    (Spatial patterns of Qualea grandiflora in cerrado fragments in Sao Paulo state). The study of spatial patterns is a helpful approach to formulating hypotheses about plant population dynamics. Our aim was to search for variation in spatial patterns of Q. grandiflora height classes at different scales within and among fragments of different cerrado physiognomies. Spatial patterns of the number of plants in subplots (5 x 5 m) were described and compared among six 0.5-ha plots placed in four fragments. We performed Moran's I correlogram analysis to describe spatial patterns and tested spatial correlations of height classes by partial Mantel tests. We found 18 to 319 plants 0.5 ha(-1). Larger plants (height >1.5 m) had a clumped pattern in all plots, varying in numbers and magnitudes of scales independently of the physiognomy. Correlogram analysis for smaller plants was possible in only three plots, where patterns were random. In two of these cases there was significant positive correlation of size classes but in the third it was not significant. Abundance and spatial patterns were as different within the same fragment as in different ones. These results show that Q. grandiflora spatial patterns cannot be predicted based on overall characteristics of cerrado physiognomy. The random-to-clumped transition with size and the spatial association of classes suggest that density dependent mortality does not seem to be an important driver of Q. grandiflora dynamics, and that spatial structure of suitable sites for recruitment to maturity may be more important.25121522

    Diffractive Higgs Production by AdS Pomeron Fusion

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    The double diffractive Higgs production at central rapidity is formulated in terms of the fusion of two AdS gravitons/Pomerons first introduced by Brower, Polchinski, Strassler and Tan in elastic scattering. Here we propose a simple self-consistent holographic framework capable of providing phenomenologically compelling estimates of diffractive cross sections at the LHC. As in the traditional weak coupling approach, we anticipate that several phenomenological parameters must be tested and calibrated through factorization for a self-consistent description of other diffractive process such as total cross sections, deep inelastic scattering and heavy quark production in the central region.Comment: 53 pages, 8 figure

    Antiophidian properties of plant extracts against Lachesis muta venom

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    Snakebites comprise a serious health problem in several countries due to their global incidence, which exceeds 2.5 million per year, and the elevated number of victim fatalities. To counteract envenomations, antivenoms have been used regularly for more than a century. Apart from side effects including anaphylactic reactions, antivenoms are not able to efficiently neutralize local tissue damage, which contributes to increasing the severity and morbidity observed in patients. This fact, in turn, may be responsible for economic hardship, particularly in rural populations of developing countries. In the present work, we evaluated the antiophidian properties of 12 Brazilian plant extracts against the hemolytic, coagulant, hemorrhagic and proteolytic effects of Lachesis muta venom. Taken together, our data revealed that most of these aqueous products were capable of inhibiting those activities at different levels, except for Sapindus saponaria extract. In contrast, Stryphnodendron barbatiman extract completely neutralized all the analyzed biological activities. Thus, we may conclude that Brazilian flora may also be useful against L. muta accidents.(FAPERJ) Fundacao de Amparo a Pesquisa do Estado do Rio de JaneiroFAPESPCNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)International Foundation for Science (IFS, Sweden
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