Sigma-model for Generalized Composite p-branes

A multidimensional gravitational model containing several dilatonic scalar fields and antisymmetric forms is considered. The manifold is chosen in the form M = M_0 x M_1 x ... x M_n, where M_i are Einstein spaces (i > 0). The block-diagonal metric is chosen and all fields and scale factors of the metric are functions on M_0. For the forms composite (electro-magnetic) p-brane ansatz is adopted. The model is reduced to gravitating self-interacting sigma-model with certain constraints. In pure electric and magnetic cases the number of these constraints is m(m - 1)/2 where m is number of 1-dimensional manifolds among M_i. In the "electro-magnetic" case for dim M_0 = 1, 3 additional m constraints appear. A family of "Majumdar-Papapetrou type" solutions governed by a set of harmonic functions is obtained, when all factor-spaces M_k are Ricci-flat. These solutions are generalized to the case of non-Ricci-flat M_0 when also some additional "internal" Einstein spaces of non-zero curvature are added to M. As an example exact solutions for D = 11 supergravity and related 12-dimensional theory are presented.Comment: 33 pages, Latex. Some corrections and rearrangements are mad

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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Reactive oxygen species and male reproductive hormones

Reports of the increasing incidence of male infertility paired with decreasing semen quality have triggered studies on the effects of lifestyle and environmental factors on the male reproductive potential. There are numerous exogenous and endogenous factors that are able to induce excessive production of reactive oxygen species (ROS) beyond that of cellular antioxidant capacity, thus causing oxidative stress. In turn, oxidative stress negatively affects male reproductive functions and may induce infertility either directly or indirectly by affecting the hypothalamus-pituitary-gonadal (HPG) axis and/or disrupting its crosstalk with other hormonal axes. This review discusses the important exogenous and endogenous factors leading to the generation of ROS in different parts of the male reproductive tract. It also highlights the negative impact of oxidative stress on the regulation and cross-talk between the reproductive hormones. It further describes the mechanism of ROS-induced derangement of male reproductive hormonal profiles that could ultimately lead to male infertility. An understanding of the disruptive effects of ROS on male reproductive hormones would encourage further investigations directed towards the prevention of ROS-mediated hormonal imbalances, which in turn could help in the management of male infertility

Mineralogy of low temperature argillic alteration in the porphyry-epithermal Çöpler gold deposit, Erzincan, East Central Turkey

The Çöpler porphyry-epithermal gold deposit, is associated with middle Eocene dioritic and granodioritic intrusive rocks. It is a porphyry Cu-Au system characterized by a potassically altered (biotite-K-feldspar-magnetite) core overprinted by extensive phyllic (quartz-sericite) and argillic (quartz – montmorillonite – kaolinite - cristobalite) alteration zones. The low temperature (argillic) alteration zone was investigated by optical microscopy and X-ray diffraction (XRD) methods. Bulk mineralogical compositions of the altered samples are quartz + feldspar + clay. Hydrothermal alteration-related clay mineral compositions of the argillic zone samples are quartz + smectite (montmorillonite) + kaolinite in the outer parts, and quartz + mixed-layer illitesmectite (I-S) and pure cristobalite in the inner parts (toward phyllic zone). Dioctahedral smectites are mainly Ca-montmorillonite, while samples close to inner parts include minor amounts of Na-smectite. Clays were neoformed within the pores of groundmass, and as replacements of plagioclase crystals. I-S has an R3 ordering type (85% illite, 15% smectite). Mineralogical associations indicate lowest grade of alteration (argillic zone), at low temperatures (< 200°C). In general pure smectite and I-S minerals represent potential minerals to aid in elucidating the origin of late stage hydrothermal fluids and the duration of hydrothermal activity which can be obtained from their stable and radiogenic isotope data