28 research outputs found

    Brane Inflation, Solitons and Cosmological Solutions: I

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    In this paper we study various cosmological solutions for a D3/D7 system directly from M-theory with fluxes and M2-branes. In M-theory, these solutions exist only if we incorporate higher derivative corrections from the curvatures as well as G-fluxes. We take these corrections into account and study a number of toy cosmologies, including one with a novel background for the D3/D7 system whose supergravity solution can be completely determined. This new background preserves all the good properties of the original model and opens up avenues to investigate cosmological effects from wrapped branes and brane-antibrane annihilation, to name a few. We also discuss in some detail semilocal defects with higher global symmetries, for example exceptional ones, that could occur in a slightly different regime of our D3/D7 model. We show that the D3/D7 system does have the required ingredients to realise these configurations as non-topological solitons of the theory. These constructions also allow us to give a physical meaning to the existence of certain underlying homogeneous quaternionic Kahler manifolds.Comment: Harvmac, 115 pages, 9 .eps figures; v2: typos corrected, references added and the last section expanded; v3: Few minor typos corrected and references added. Final version to appear in JHE

    The Physics of the B Factories

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    Effects of chloroacetaldehyde in 2-chloroethanol-induced cardiotoxicity

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    Cardiovascular effects have often been found in 2-chloroethanol (2-CE) intoxicated patients, but the 2-CE elicits cardiovascular toxicity mechanism is not clear. Recently, we have found that chloroacetaldehyde (CAA) accumulation in 2-CE-intoxicated rat's blood and play an important role in 2-CE intoxication. In this study, we used an isolated rat atrium model to examine the cardiotoxicity of 2-CE and CAA. Results indicated that 2-CE did not cause tension arrest in isolated rat right atria, but CAA did. 2-CE caused tension inhibition in the isolated rat left atria. In addition, CAA caused significant tension inhibition and contracture in the isolated rat left atria. Nifedipine, an L-type calcium channel blocker, decreased CAA-induced tension inhibition and contracture. Meanwhile, atrial nNOS and calmodulin (CaM) had significantly greater expression in the 2-CE group and the CM group than control group. Nifedipine could decrease CAA-induced nNOS and CaM expression. 2-CE-induced cardiovascular toxicity might be due to its metabolite CM. CAA-induced cardiovascular toxicity might be mediated by calcium channel and nifedipine protected against nNOS-triggered cardiovascular effects. (C) 2011 Elsevier Ltd. All rights reserved

    Lipid peroxidation and antioxidant status in workers exposed to PCDD/Fs of metal recovery plants

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    Secondary copper smelters, which primarily utilize the waste materials that contain organic impurities, and the zinc recovery plant, which handles mostly fly ash and slag from the iron and steel industry, are major emission sources of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in Taiwan. In this study, we compared the levels of erythrocyte glutathione (GSH), erythrocyte superoxide dismutase (SOD) and plasma malondialdehyde (MDA) in workers at a secondary copper smelting plant and a zinc recovery plant who may have been exposed to PCDD/Fs. Though the PCDD/F levels were higher in workers of zinc recovery plant than those of secondary copper smelting plant, no significant difference was found for serum PCDD/F levels between the two kinds of plants. We observed a significant difference in plasma MDA levels between workers at the zinc recovery plant (2.54 mu M) and those at the copper smelting plant (1.79 mu M). There was and a significant positive correlation between plasma MDA levels and the PCDD/Fs levels. In addition, we observed that the MDA levels were not affected by smoking and exercise status. Therefore, the data suggest that the MDA levels of the metal recovery workers are influenced by their PCDD/F exposure. The erythrocyte SOD activity in workers from the zinc recovery plant was marginally higher than that from the secondary copper plant (196 vs. 146 units/ml, p < 0.06). In both plants, large variations in the MDA and SOD levels were found, especially in the high-PCDD/Fs-exposure group, which may be attributed, at least partially, to the differences in smoking status and the number of cigarettes smoked. Overall, our results indicate a higher oxidative stress in workers of the zinc recovery plant than in workers of the secondary copper smelting plant in Taiwan. (c) 2006 Published by Elsevier B.V

    Early onset pneumonia in patients with cholinesterase inhibitor poisoning

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    Background and objective: Organophosphates and carbamates are potent cholinesterase inhibitors that are widely used as insecticides in agriculture. Pneumonia is a frequent complication of cholinesterase inhibitor poisoning (CIP) and a risk factor for death. The aim of this retrospective study was to assess the risk factors for pneumonia in patients with CIP. Methods: The medical records of 155 patients, who were treated for CIP in a 1300-bed medical centre in central Taiwan, from January 2002 to December 2004, were retrospectively analysed. Pneumonia was diagnosed by a new or persistent infiltrate on CXR, as well as clinical symptoms. Demographic data, comorbidities, acute respiratory failure and in-hospital mortality were also recorded. Results: Of the 155 patients, 31 (20%) died and 92 (59.4%) developed acute respiratory failure. Thirty-four patients (21.9%) were diagnosed with early onset pneumonia during hospitalization. Acute respiratory failure (OR 12.10, 95% CI: 2.55-57.45), underlying cardiovascular disease (OR 3.02, 95% CI: 1.02-8.91), undergoing gastric lavage at peripheral hospitals (OR 6.23, 95% CI: 1.52-25.98) and development of respiratory failure at the study centre after gastric lavage (OR 3.43, 95% CI: 1.17-10.0) were predictive factors for early onset pneumonia. Cardiopulmonary resuscitation (OR 23.58, 95% CI: 6.03-92.29), early onset pneumonia (OR 7.45, 95% CI: 2.02-27.5) and lower Glasgow coma score (OR 1.26, 95% CI: 1.08-1.48) were predictive factors for mortality. Conclusions: Pneumonia was a significant risk factor for death in patients with CIP. In addition to aggressive management of patients with CIP who develop respiratory failure, careful respiratory evaluation before and after gastric lavage would help to decrease the incidence of early onset pneumonia in patients with CIP
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