Small-scale Interaction of Turbulence with Thermonuclear Flames in Type Ia Supernovae

Microscopic turbulence-flame interactions of thermonuclear fusion flames occuring in Type Ia Supernovae were studied by means of incompressible direct numerical simulations with a highly simplified flame description. The flame is treated as a single diffusive scalar field with a nonlinear source term. It is characterized by its Prandtl number, Pr << 1, and laminar flame speed, S_L. We find that if S_L ~ u', where u' is the rms amplitude of turbulent velocity fluctuations, the local flame propagation speed does not significantly deviate from S_L even in the presence of velocity fluctuations on scales below the laminar flame thickness. This result is interpreted in the context of subgrid-scale modeling of supernova explosions and the mechanism for deflagration-detonation-transitions.Comment: 8 pages, 6 figures, accepted by Astrophys.

Tidal Interaction between a Fluid Star and a Kerr Black Hole in Circular Orbit

We present a semi-analytic study of the equilibrium models of close binary systems containing a fluid star (mass $m$ and radius $R_0$) and a Kerr black hole (mass $M$) in circular orbit. We consider the limit $M\gg m$ where spacetime is described by the Kerr metric. The tidally deformed star is approximated by an ellipsoid, and satisfies the polytropic equation of state. The models also include fluid motion in the stellar interior, allowing binary models with nonsynchronized stellar spin (as expected for coalescing neutron star-black hole binaries) to be constructed. Tidal disruption occurs at orbital radius $r_{\rm tide}\sim R_0(M/m)^{1/3}$, but the dimensionless ratio $\hat r_{\rm tide}=r_{\rm tide}/[R_0(M/m)^{1/3}]$ depends on the spin parameter of the black hole as well as on the equation of state and the internal rotation of the star. We find that the general relativistic tidal field disrupts the star at a larger $\hat r_{\rm tide}$ than the Newtonian tide; the difference is particularly prominent if the disruption occurs in the vicinity of the black hole's horizon. In general, $\hat r_{\rm tide}$ is smaller for a (prograde rotating) Kerr black hole than for a Schwarzschild black hole. We apply our results to coalescing black hole-neutron star and black hole-white dwarf binaries. The tidal disruption limit is important for characterizing the expected gravitational wave signals and is relevant for determining the energetics of gamma ray bursts which may result from such disruption.Comment: 29 pages including 8 figures. Minor changes and update. To appear in ApJ, March 20, 2000 (Vol.532, #1

Shear Viscosity and Oscillations of Neutron Star Crusts

We calculate the electron shear viscosity (determined by Coulomb electron collisions) for a dense matter in a wide range of parameters typical for white dwarf cores and neutron star crusts. In the density range from ~10^3 g cm^-3 to 10^7-10^10 g cm^-3 we consider the matter composed of widely abundant astrophysical elements, from H to Fe. For higher densities, 10^10-10^14 g cm^-3, we employ the ground-state nuclear composition, taking into account finite sizes of atomic nuclei and the distribution of proton charge over the nucleus. Numerical values of the viscosity are approximated by an analytic expression convenient for applications. Using the approximation of plane-parallel layer we study eigenfrequencies, eigenmodes and viscous damping times of oscillations of high multipolarity, l~500-1000, localized in the outer crust of a neutron star. For instance, at l~500 oscillations have frequencies f >= 40 kHz and are localized not deeper than ~300 m from the surface. When the crust temperature decreases from 10^9 K to 10^7 K, the dissipation time of these oscillations (with a few radial nodes) decreases from ~1 year to 10-15 days.Comment: 23 pages, 13 figure

Physics of Neutron Star Crusts

The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.Comment: 182 pages, published version available at <http://www.livingreviews.org/lrr-2008-10

AI Based Airplane Air Pollution Identification Architecture Using Satellite Imagery

Air Pollution has become an important problem for governments, researchers, and environmentalists over the last few decades. There are many primary transportation sources of air pollution including airplanes. Automatic airplane recognition in high-resolution satellite images has many applications. One of the applications using artificial intelligence and satellite imagery to design lean smart cities and work on primary sources of transportation air pollutions detection using high-resolution satellite imagery. With the help of satellite imagery and artificial intelligence model, airplane count and detection can be done with accuracy. This paper aims to analyze satellite images in order to help cities to have an idea about the number of planes in the city region. This paper presents web-based end to end aircraft identification framework based on F-RCNN. Utilizing artificial intelligence using deep learning is the state-of-the-art technique to identify the number of planes in a given region with the help of satellite images. The results of the self-made dataset show that the improved F-RCNN has better precision, detection accuracy and masking accuracy which improves the overall efficiency of pollution source identification project in the smart city. The proposed method tested on an image dataset including several airports and non-airports regions. The detection rate could reach approximately 92% accuracy and reduced computation time

Transcervical resection of endometrium as a conservative management of dysfunctional uterine bleeding in premenopausal patients

Background: Dysfunctional uterine bleeding (DUB) affects 10% to 15% women of reproductive age group. A prospective observational study was performed to study the efficacy, rate of satisfaction and adverse effects of Transcervical resection of endometrium (TCRE) in the treatment of DUB in premenopausal women.Methods: 30 patients with DUB attending the hospital underwent TCRE and patients were followed up after 6 week, 3 months, 6 months up to 1 year and there bleeding score was calculated. Their response to treatment, complications and satisfaction rate were studied.Results: 43.3% of the women in this study were in the age group of 40-44 years. Post TCRE, 43.33% (n=13) had hypomenorrhea. 33.33% (n=10) had regular cycle, 13.33% (n=4) women had amenorrhea and 10% (n=3) had no response and underwent hysterectomy. 86.66% (n=26) women were satisfied with the treatment whereas 13.33% (n=4) were not satisfied. One patient had uterine perforation and serosal bowel injury due to extended cautery injury. Bleeding reduced considerably and a statistically significant (paired t-test, p-value &lt;0.05) difference was observed in pre and post procedure (6 weeks, 3 months, 6 months and 1 year) bleeding scores.Conclusions: Considering advantages like shorter operative time, uterine conservation and early mobility TCRE is a procedure of choice in patients in whom hysterectomy is either technically difficult or medically contraindicated or in those who are not suitable for long term medical management

Functions of LIM proteins in cell polarity and chemotactic motility

LimC and LimD are two novel LIM proteins of Dictyostelium, which are comprised of double and single LIM domains, respectively. Green fluorescent protein-fused LimC and LimD proteins preferentially accumulate at areas of the cell cortex where they co-localize with actin and associate transiently with cytoskeleton-dependent dynamic structures like phagosomes, macropinosomes and pseudopods. Furthermore, both LimC and LimD interact directly with F-actin in vitro. Mutant cells that lack either LimC or LimD, or both, exhibit normal growth. They are, however, significantly impaired in growth under stress conditions and are highly sensitive to osmotic shock, suggesting that LimC and LimD contribute towards the maintenance of cortical strength. Moreover, we noted an altered morphology and F-actin distribution in LimD(–) and LimC(–)/D(–) mutants, and changes in chemotactic motility associated with an increased pseudopod formation. Our results reveal both unique and overlapping roles for LimC and LimD, and suggest that both act directly on the actin cytoskeleton and provide rigidity to the cortex

Copper-catalyzed amination of aryl halides: single-step synthesis of triarylamines

A simple and efficient methodology for the synthesis of triarylamines in a single step has been demonstrated using a ligand-free CuI catalyst and potassium tertiary butoxide as the base. Use of chelating ligands leads to the formation of triarylamine derivatives selectively (95% yield) with high catalytic activity. A simple and efficient methodology for the synthesis of triarylamines in a single step has been demonstrated using ligand-free CuI catalyst and potassium tertiary butoxide as the base. Use of chelating ligands leads to the formation of triarylamine derivatives selectively (95% yield) with high catalytic activity

Synthesis of triarylamines by copper-catalyzed amination of aryl halides

A simple and efficient methodology for the synthesis of triphenylamine (TPA) in a single step has been demonstrated using copper catalyst with a ligand. The effect of parameters such as catalyst precursors, ligands, bases and solvents on activity and selectivity to triphenylamine were studied at 115 &#176;C. Best results were obtained using 2,6-diphenylpyridine as a ligand (94% yield of TPA)