285 research outputs found

    Decomposition of stochastic flows with automorphism of subbundles component

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    We show that given a GG-structure PP on a differentiable manifold MM, if the group G(M)G(M) of automorphisms of PP is big enough, then there exists the quotient of an stochastic flows phitphi_t by G(M)G(M), in the sense that ϕt=ξtρt\phi_t = \xi_t \circ \rho_t where ξtG(M)\xi_t \in G(M), the remainder ρt\rho_t has derivative which is vertical but transversal to the fibre of PP. This geometrical context generalizes previous results where MM is a Riemannian manifold and ϕt\phi_t is decomposed with an isometric component, see Liao \cite{Liao1} and Ruffino \cite{Ruffino}, which in our context corresponds to the particular case of an SO(n)-structure on MM.Comment: To appear in Stochastics and Dynamics, 201

    Topics on the geometry of D-brane charges and Ramond-Ramond fields

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    In this paper we discuss some topics on the geometry of type II superstring backgrounds with D-branes, in particular on the geometrical meaning of the D-brane charge, the Ramond-Ramond fields and the Wess-Zumino action. We see that, depending on the behaviour of the D-brane on the four non-compact space-time directions, we need different notions of homology and cohomology to discuss the associated fields and charge: we give a mathematical definition of such notions and show their physical applications. We then discuss the problem of corretly defining Wess-Zumino action using the theory of p-gerbes. Finally, we recall the so-called *-problem and make some brief remarks about it.Comment: 29 pages, no figure

    Dengue em localidade urbana da região sudeste do Brasil: aspectos epidemiológicos

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    A dengue fever epidemic which occurred in Ribeirão Preto County, S. Paulo State, Brazil, during the period November, 1990 to March, 1991 has been analysed else where. The general aspects of dengue epidemiology and control have been reviewed in this article. Emphasis is given to the analysis of some factors involved in the risk of dengue haemorrhagic fever and ecological aspects of the vector, as well as to the appropriateness of strategies for dengue eradication or control. Epidemiological characteristics of dengue, mainly those related to its occurrence in different geographical areas and periods of time are described. The Ribeirão Preto epidemic has thus, been set within the context of the spread of the disease at global level, in the Americas, and particularly in Brazil and S. Paulo State.Foram revistos alguns aspectos da epidemiologia do dengue, como parte do estudo de epidemia ocorrida no Município de Ribeirão Preto, Estado de São Paulo, no período de novembro de 1990 a março de 1991. Deu-se ênfase aos fatores envolvidos no risco de ocorrência do dengue hemorrágico/síndrome de choque do dengue. Traçou-se um quadro de referência a respeito do comportamento epidemiológico do dengue através do tempo e em diferentes áreas geográficas. A epidemia de Ribeirão Preto foi situada no contexto da progressão do dengue em nível mundial, nas Américas, e particulamente no Brasil e Estado de São Paulo

    Moderate-intensity exercise alters markers of alternative activation in circulating monocytes in females: a putative role for PPARγ

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    Monocytes may be primed towards differentiation into classically activated M1 macrophages or alternatively activated M2 macrophages. M1 macrophages greatly contribute to the inflammation which promotes insulin resistance, whereas M2 macrophages resolve inflammation. We have previously shown that exercise increases M2 marker expression in mixed mononuclear cells, possibly via activation of the nuclear transcription factor PPARγ. However, these effects have not been demonstrated specifically within monocytes. Thus, we aimed to investigate whether moderate-intensity exercise elicited similar effects on monocytic M1/M2 marker expression and PPARγ activity to those reported previously in mononuclear cells, so as to further elucidate the mechanisms by which exercise may alter inflammatory status and, accordingly, prevent insulin resistance

    Atomic Force Microscopy Study of the Kinetic Roughening in Nanostructured Gold Films on SiO2

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    Dynamic scaling behavior has been observed during the room-temperature growth of sputtered Au films on SiO2using the atomic force microscopy technique. By the analyses of the dependence of the roughness, σ, of the surface roughness power,P(f), and of the correlation length,ξ, on the film thickness,h, the roughness exponent,α = 0.9 ± 0.1, the growth exponent,β = 0.3 ± 0.1, and the dynamic scaling exponent,z = 3.0 ± 0.1 were independently obtained. These values suggest that the sputtering deposition of Au on SiO2at room temperature belongs to a conservative growth process in which the Au grain boundary diffusion plays a dominant role

    A comparison of the health benefits of reduced-exertion high-intensity interval training (REHIT) and moderate-intensity walking in type 2 diabetes patients

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    Reduced-exertion high-intensity interval training (REHIT) is a genuinely time-efficient intervention that can improve aerobic capacity and insulin sensitivity in sedentary individuals. The present study compared the effects of REHIT and moderate-intensity walking on health markers in patients with type 2 diabetes (T2D) in a counter-balanced crossover study. Sixteen men with T2D (mean ± SD age: 55 ± 5 years, body mass index: 30.6 ± 2.8 kg·m−2, maximal aerobic capacity: 27 ± 4 mL·kg−1·min−1) completed 8 weeks of REHIT (three 10-min low-intensity cycling sessions/week with two “all-out” 10–20-s sprints) and 8 weeks of moderate-intensity walking (five 30-min sessions/week at an intensity corresponding to 40%–55% of heart-rate reserve), with a 2-month wash-out period between interventions. Before and after each intervention, participants underwent an incremental fitness test, an oral glucose tolerance test (OGTT), a whole-body dual-energy X-ray absorptiometry scan, and continuous glucose monitoring. REHIT was associated with a significantly larger increase in maximal aerobic capacity compared with walking (7% vs. 1%; time × intervention interaction effect:p< 0.05). Both REHIT and walking decreased resting mean arterial pressure (−4%; main effect of time:p< 0.05) and plasma fructosamine (−5%; main effect of time:p< 0.05). Neither intervention significantly improved OGTT-derived measures of insulin sensitivity, glycaemic control measured using continuous glucose monitors, blood lipid profile, or body composition. We conclude that REHIT is superior to a 5-fold larger volume of moderate-intensity walking in improving aerobic fitness, but similar to walking REHIT is not an effective intervention for improving insulin sensitivity or glycaemic control in T2D patients in the short term
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