12,868 research outputs found
Atmospheric Sulfur Photochemistry on Hot Jupiters
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
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
We consider the supersymmetry (SUSY) transformations in the chiral Lagrangian
for supergravity (SUGRA) with the complex tetrad following the method
used in the usual 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
High magnetic field superconducting properties of niobium stannide films and shielding characterictics of stannide layer
Rigidity analysis of HIV-1 protease
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
- …