1,398 research outputs found
Dynamical vs. Auxiliary Fields in Gravitational Waves around a Black Hole
The auxiliary/dynamic decoupling method of hep-th/0609001 applies to
perturbations of any co-homogeneity 1 background (such as a spherically
symmetric space-time or a homogeneous cosmology). Here it is applied to compute
the perturbations around a Schwarzschild black hole in an arbitrary dimension.
The method provides a clear insight for the existence of master equations. The
computation is straightforward, coincides with previous results of
Regge-Wheeler, Zerilli and Kodama-Ishibashi but does not require any ingenuity
in either the definition of variables or in fixing the gauge. We note that the
method's emergent master fields are canonically conjugate to the standard ones.
In addition, our action approach yields the auxiliary sectors.Comment: 26 page
Energy and Vorticity Spectra in Turbulent Superfluid He from to
We discuss the energy and vorticity spectra of turbulent superfluid He in
all the temperature range from up to the phase transition "
point", K. Contrary to classical developed turbulence
in which there are only two typical scales, i.e. the energy injection and
the dissipation scales , here the quantization of vorticity introduces
two additional scales, i.e the vortex core radius and the mean vortex
spacing . We present these spectra for the super- and normal-fluid
components in the entire range of scales from to including the
cross-over scale where the hydrodynamic eddy-cascade is replaced by the
cascade of Kelvin waves on individual vortices. At this scale a bottleneck
accumulation of the energy was found earlier at .
We show that even very small mutual friction dramatically suppresses the
bottleneck effect due to the dissipation of the Kelvin waves. Using our results
for the spectra we estimate the Vinen "effective viscosity" in the
entire temperature range and show agreement with numerous experimental
observation for .Comment: 20 pages, 5 figure
Shuffle on array languages generated by array grammars
Motivated by the studies done by G. Siromoney et al. (1973) and Alexan-
dru Mateescu et al. (1998) we examine the language theoretic results related to shuf- fle on trajectories by making use of Siromoney array grammars such as (R : R)AG, (R : C F )AG, (C F : R)AG, (C F : C F )AG, (C S : R)AG, (C S : C S)AG and (C F : C S)AG which are more powerful than the Siromoney matrix grammars (1972)
and are used to make digital pictures
CORRELATION OF TOTAL ANTIOXIDANT STATUS (TAS) WITH DNA DAMAGE IN HIV/AIDS PATIENTS
Abstract Title: Correlation of total antioxidant status (TAS) with DNA damage in HIV/AIDS patients. Background: The antioxidant deficiency in HIV-positive populations is probably due to increased utilization of antioxidant micronutrients because of increased oxidative stress rather than to inadequate dietary intake [1].  Objectives: The study had 2 principal objectives. The first was to determine total antioxidant status (TAS) and DNA damage in HIV /AIDS patients on varying antiretroviral therapy(ART)  and those not on ART. The second objective was to ascertain whether there is any correlation between TAS and oxidative DNA damage in these patients. Design: This was a cross-sectional study involving 300 HIV positive and 100 HIV-negative subjects aged 20–60 yrs. Results: The varying ART has not have much effect on TAS levels but there was different levels of DNA damage in ART first line, ART second line and ART not yet started patients. There is a negative correlation between TAS & DNA damage. Conclusions: In this study, we observed that ART plays a significant role in the oxidative DNA damage. Decreased TAS is associated with increased DNA damage. Â
Dynamical excitation of space-time modes of compact objects
We discuss, in the perturbative regime, the scattering of Gaussian pulses of
odd-parity gravitational radiation off a non-rotating relativistic star and a
Schwarzschild Black Hole. We focus on the excitation of the -modes of the
star as a function of the width of the pulse and we contrast it with the
outcome of a Schwarzschild Black Hole of the same mass. For sufficiently narrow
values of , the waveforms are dominated by characteristic space-time modes.
On the other hand, for sufficiently large values of the backscattered
signal is dominated by the tail of the Regge-Wheeler potential, the
quasi-normal modes are not excited and the nature of the central object cannot
be established. We view this work as a useful contribution to the comparison
between perturbative results and forthcoming -mode 3D-nonlinear numerical
simulation.Comment: RevTeX, 9 pages, 7 figures, Published in Phys. Rev.
A case of near miss maternal mortality
Eclampsia is a common cause of maternal morbidity and at times, mortality. Usually patients show dramatic improvement soon after delivery. But rarely eclampsia, dealt by obstetricians often, can herald an underlying life-threatening disease process requiring intensive care support and multi- disciplinary care. Such a case is being reported here
Probability distribution of residence-times of grains in sandpile models
We show that the probability distribution of the residence-times of sand
grains in sandpile models, in the scaling limit, can be expressed in terms of
the survival probability of a single diffusing particle in a medium with
absorbing boundaries and space-dependent jump rates. The scaling function for
the probability distribution of residence times is non-universal, and depends
on the probability distribution according to which grains are added at
different sites. We determine this function exactly for the 1-dimensional
sandpile when grains are added randomly only at the ends. For sandpiles with
grains are added everywhere with equal probability, in any dimension and of
arbitrary shape, we prove that, in the scaling limit, the probability that the
residence time greater than t is exp(-t/M), where M is the average mass of the
pile in the steady state. We also study finite-size corrections to this
function.Comment: 8 pages, 5 figures, extra file delete
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