95 research outputs found

    Using Statistical Simulation to Visualize and Quantify Day-to-Day Measurement Error in Indirect Calorimetry

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    Please refer to the pdf version of the abstract located adjacent to the title

    Effects of Cognitive Fatigue on High Intensity Circuit Exercise: Preliminary study

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    Estimating abundance and habitat suitability in a micro-endemic snake: the Walser viper

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    Recently described species suffer lack of information that hampers setting up appropriate conservation strategies. The situation is particularly complex with micro-endemic snakes, for which detection and monitoring are particularly challenging. The Walser viper Vipera walser is a recently described snake inhabiting a small area of the SW Italian alps. We combined information on species distribution with repeated monitoring to identify the areas most suitable for the species, and to obtain estimates of species abundance. Species distribution models were used to identify the topographical, climatic, and land-cover features related to the occurrence of vipers. Furthermore, repeated transects and N-mixture models were used to estimate abundance and to identify factors related to the variation of abundance. The available data suggested that the species has a disjunct range, with a Northern range of ~45 km2 , and a southern range of ~225 km2. Distribution models suggested that vipers are associated with areas with open egetation,altitude between 1300 and 2300 m, high precipitation, low forest cover, low slope, and southern aspect. N-mixture models confirmed very low detection probability of these vipers, and suggested that the species has a low abundance,with the highest abundance in south-facing plots. We provide the first quantitative information on habitats and abundance variation for Walser vipers. The broad confidence intervals of abundance estimates exemplify the complexity of providing range-wide measures of abundance for secretive species. Given the narrow range of these vipers, continuous monitoring is required to understand how they respond to ongoing environmental changes in mountainous areas

    Thrombospondin-1 is downregulated by anoxia and suppresses tumorigenicity of human glioblastoma cells.

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    Angiogenesis, the sprouting of new capillaries from preexisting blood vessels, results from a disruption of the balance between stimulatory and inhibitory factors. Here, we show that anoxia reduces expression of thrombospondin-1 (TSP-1), a natural inhibitor of angiogenesis, in glioblastoma cells. This suggests that reduced oxygen tension can promote angiogenesis not only by stimulating the production of inducers, such as vascular endothelial growth factor, but also by reducing the production of inhibitors. This downregulation may significantly contribute to glioblastoma development, since we show that an increase in TSP-1 expression is sufficient to strongly suppress glioblastoma cell tumorigenicity in vivo

    Information theory in the study of anisotropic radiation

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    Information theory is used to perform a thermodynamic study of non equilibrium anisotropic radiation. We limit our analysis to a second-order truncation of the moments, obtaining a distribution function which leads to a natural closure of the hierarchy of radiative transfer equations in the so-called variable Eddington factor scheme. Some Eddington factors appearing in the literature can be recovered as particular cases of our two-parameter Eddington factor. We focus our attention in the study of the thermodynamic properties of such systems and relate it to recent nonequilibrium thermodynamic theories. Finally we comment the possibility of introducing a nonequilibrium chemical potential for photons.Comment: 1 eps figure upon request by e-mail, to appear in Journal of Physics

    A Contribution to the estimation of binary halide and pseudo-halide equilibrium constants using a linear extrapolation methodology

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    The molar single ion activity coefficient (yF) of fluoride ions was determined at 25 °C and ionic strengths between 0.100 and 3.00 mol L-1 NaClO4 using an ion-selective electrode. The activity coefficient dependency on ionic strength was determined to be ΦF = log yF = 0.2315I - 0.041I². The function ΦF(I), combined with functions obtained in previous work for copper (ΦCu) and hydrogen (ΦH), allowed us to make the estimation of the stoichiometric and thermodynamic protonation constants of some halides and pseudo-halides as well as the formation constants of some pseudo-halides and fluoride 1:1 bivalent cation complexes. The calculation procedure proposed in this paper is consistent with critically-selected experimental data. It was demonstrated that it is possible to use ΦF(I) for predicting the thermodynamic equilibrium parameters independently of Pearson's hardness of acids and bases.O coeficiente de atividade molar individual do íon fluoreto (yF) foi determinado a 25° C para valores de força iônica entre 0,100 and 3,00 mol L-1 (NaClO4) usando-se um eletrodo íon-seletivo. A dependência do coeficiente de atividade com a força iônica é explicada pela equação ΦF = log yF = 0,2315I - 0,041I². A função ΦF(I), foi associada a outras funções estimadas em trabalhos anteriores, por exemplo,ΦCu(I) para cobre, e ΦH(I) para íon hidrogênio, possibilitando a estimativa de constantes de estabilidade estequiométricas e termodinâmicas tanto para equilíbrios de protonação de alguns haletos e pseudo-haletos como para as constantes de formação de complexos 1:1 de metais bivalentes com fluoreto e pseudo-haletos. O procedimento de cálculo proposto é consistente com dados experimentais criticamente selecionados da literatura. Verificou-se que é possível usar ΦF(I) na previsão de parâmetros de equilíbrio termodinâmicos independentemente do caráter HSAB de Pearson .135141Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

    A Contribution to the estimation of binary halide and pseudo-halide equilibrium constants using a linear extrapolation methodology

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    The molar single ion activity coefficient (y(F)) of fluoride ions was determined at 25 degrees C and ionic strengths between 0.100 and 3.00 mol L(-1) NaClO(4) using an ion-selective electrode. The activity coefficient dependency on ionic strength was determined to be Phi(F) = log y(F) = 0.2315I-0.041I(2). The function Phi(F)(I), combined with functions obtained in previous work for copper (Phi(Cu)) and hydrogen (Phi(H)), allowed us to make the estimation of the stoichiometric and thermodynamic protonation constants of some halides and pseudo-halides as well as the formation constants of some pseudo-halides and fluoride 1:1 bivalent cation complexes. The calculation procedure proposed in this paper is consistent with critically-selected experimental data. It was demonstrated that it is possible to use Phi(F)(I) for predicting the thermodynamic equilibrium parameters independently of Pearson's hardness of acids and bases

    Expression of ADAMTS-8, a secreted protease with antiangiogenic properties, is downregulated in brain tumours

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    Angiogenesis and extracellular matrix degradation are key events in tumour progression, and factors regulating stromal–epithelial interactions and matrix composition are potential targets for the development of novel anti-invasive/antiangiogenic therapies. Here, we examine the expression of ADAMTS-8, a secreted protease with antiangiogenic properties, in brain tissues. Using quantitative RT–polymerase chain reaction (PCR), high, equivalent expression of ADAMTS-8 was found in normal whole brain, cerebral cortex, frontal lobe, cerebellum and meninges. ADAMTS-8 expression in 34 brain tumours (including 22 high-grade gliomas) and four glioma cell lines indicated at least two-fold reduction in mRNA compared to normal whole brain in all neoplastic tissues, and no detectable expression in 14 out of 34 (41%) tumours or four out of four (100%) cell lines. In contrast, differential expression of TSP1 and VEGF was seen in nine out of 15 (60%) and seven out of 13 (54%) tumours, with no relationship in the expression of these genes. Immunohistochemistry and Western analysis indicated downregulation of ADAMTS-8 protein in >77% tumours. Methylation-specific PCR analysis of ADAMTS-8 indicated promoter hypermethylation in one out of 24 brain tumours (a metastasis) and three out of four glioma cell lines suggesting an alternative mechanism of downregulation. These data suggest a role for ADAMTS-8 in brain tumorigenesis, warranting further investigation into its role in regulation of tumour angiogenesis and local invasion
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