12,839 research outputs found

    Atmospheric Sulfur Photochemistry on Hot Jupiters

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    We develop a new 1D photochemical kinetics code to address stratospheric chemistry and stratospheric heating in hot Jupiters. Here we address optically active S-containing species and CO2 at 1200 < T < 2000 K. HS (mercapto) and S2 are highly reactive species that are generated photochemically and thermochemically from H2S with peak abundances between 1-10 mbar. S2 absorbs UV between 240 and 340 nm and is optically thick for metallicities [SH] > 0 at T > 1200 K. HS is probably more important than S2, as it is generally more abundant than S2 under hot Jupiter conditions and it absorbs at somewhat redder wavelengths. We use molecular theory to compute an HS absorption spectrum from sparse available data and find that HS should absorb strongly between 300 and 460 nm, with absorption at the longer wavelengths being temperature sensitive. When the two absorbers are combined, radiative heating (per kg of gas) peaks at 100 microbars, with a total stratospheric heating of about 8 x 10^4 W/m^2 for a jovian planet orbiting a solar-twin at 0.032 AU. Total heating is insensitive to metallicity. The CO2 mixing ratio is a well-behaved quadratic function of metallicity, ranging from 1.6 x 10^-8 to 1.6 x 10^-4 for -0.3 < [M/H] < 1.7. CO2 is insensitive to insolation, vertical mixing, temperature (1200 < T <2000 K), and gravity. The photochemical calculations confirm that CO2 should prove a useful probe of planetary metallicity.Comment: Astrophysical Journal Lett. in press; important revision includes effect of updated thermodynamic data and a new opacity sourc

    Central obesity and advanced liver stiffness in Hepatitis B: Result from golestan hepatitis B cohort study

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    Background: Chronic infection with the hepatitis B virus and obesity may both contribute synergistically to liver disease, although relatively few studies have investigated this hypothesis. Therefore, in this study, we evaluated the relationship between central obesity and the liver stiffness in the Golestan Hepatitis B cohort study (GHBCS). Methods: Our study included 304 chronic hepatitis B (CHB) patients enrolled from GHBCS. Liver stiffness measurement (LSM) and laboratory tests were performed after a follow-up of 4 years (2012). The hepatitis B viral load was measured at the baseline and follow-up using the real-time PCR method. Waist circumference ≥102 cm in men and ≥ 89 cm in women (central obesity) was considered to be abnormal. Advanced liver stiffness (ALS) was defined as LSM≥8 KPa. Statistical analysis was performed using SPSS-V17. Logistic regression was used to test predictors of advanced liver stiffness (LSM ≥ 8 KPa). Linear regression was used to test the predictive value of variables in ALT (as a continuous variable). P-value of less than 0.05 was considered statistically significant. Results: Among these CHB patients, 19 (7.4%) cases with a mean (±SD) age of 49.5 (±6.3) developed ALS after 4 years of follow-up. Multivariate analysis showed a significant predictive role of central obesity and viral load in ALS. Conclusions: Central obesity is related to the liver stiffness in chronic hepatitis B patients. © 2015, Academy of Medical Sciences of I.R. Iran. All rights reserved

    Supersymmetry algebra in N = 1 chiral supergravity

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    We consider the supersymmetry (SUSY) transformations in the chiral Lagrangian for N=1N = 1 supergravity (SUGRA) with the complex tetrad following the method used in the usual N=1N = 1 SUGRA, and present the explicit form of the SUSY trasformations in the first-order form. The SUSY transformations are generated by two independent Majorana spinor parameters, which are apparently different from the constrained parameters employed in the method of the 2-form gravity. We also calculate the commutator algebra of the SUSY transformations on-shell.Comment: 10 pages, late

    High magnetic field superconducting properties of Nb3Sn films Final report

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    High magnetic field superconducting properties of niobium stannide films and shielding characterictics of stannide layer

    Rigidity analysis of HIV-1 protease

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    We present a rigidity analysis on a large number of X-ray crystal structures of the enzyme HIV-1 protease using the 'pebble game' algorithm of the software FIRST. We find that although the rigidity profile remains similar across a comprehensive set of high resolution structures, the profile changes significantly in the presence of an inhibitor. Our study shows that the action of the inhibitors is to restrict the flexibility of the beta-hairpin flaps which allow access to the active site. The results are discussed in the context of full molecular dynamics simulations as well as data from NMR experiments.Comment: 4 pages, 3 figures. Conference proceedings for CMMP conference 2010 which was held at the University of Warwic
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