9,783 research outputs found
The effect of Pressure in Higher Dimensional Quasi-Spherical Gravitational Collapse
We study gravitational collapse in higher dimensional quasi-spherical
Szekeres space-time for matter with anisotropic pressure. Both local and global
visibility of central curvature singularity has been studied and it is found
that with proper choice of initial data it is possible to show the validity of
CCC for six and higher dimensions. Also the role of pressure in the collapsing
process has been discussed.Comment: 11 pages, 6 figures, RevTeX styl
Collapse Dynamics of a Star of Dark Matter and Dark Energy
In this work, we study the collapse dynamics of an inhomogeneous spherically
symmetric star made of dark matter (DM) and dark energy (DE). The dark matter
is taken in the form of a dust cloud while anisotropic fluid is chosen as the
candidate for dark energy. It is investigated how dark energy modifies the
collapsing process and is examined whether dark energy has any effect on the
Cosmic Censorship Conjecture. The collapsing star is assumed to be of finite
radius and the space time is divided into three distinct regions and
, where represents the boundary of the star and
denotes the interior (exterior) of the star. The junction
conditions for matching over are specified. Role of Dark
energy in the formation of apparent horizon is studied and central singularity
is analyzed.Comment: 13 page
Naked Singularities in Higher Dimensional Szekeres Space-time
In this paper we study the quasi-spherical gravitational collapse of (n+2)
dimensional Szekeres space-time. The nature of the central shell focusing
singularity so formed is analyzed by studying both the radial null and
time-like geodesic originated from it. We follow the approach of Barve et al to
analyze the null geodesic and find naked singularity in different situations.Comment: 11 Latex Pages, 4 figures, RevTex styl
A broad-spectrum antibiotic, DCAP, reduces uropathogenic Escherichia coli infection and enhances vorinostat anticancer activity by modulating autophagy
Optical polarimetry and photometry of comet 17P/Holmes
Comet 17P/Holmes was observed for linear polarisation using the optical
polarimeter mounted on the 1.2m telescope atop Gurushikhar peak near Mt. Abu
during the period November-December 2007. Observations were conducted through
the IHW narrow band (continuum) filters. During the observing run the phase
angle was near at which the comet showed negative polarisation. On
the basis of the observed polarisation data we find comet 17P/Holmes to be a
typical comet with usual dust characteristics. We note that radial rate of
change of brightness in coma in red band is higher than that in blue band; it
has decreased by a factor of 3.6 and 2.5 respectively in red and blue bands
during the November - December run, indicating relative increase in the
abundance of smaller dust particles out ward. Radial brightness variation seen
near the nucleus on November 6 is indicative of the presence of a blob or
shocked region beyond 10" from the nucleus which has gradually smoothened by
December 13. The brightness distribution is found steeper during November 5-7
as compared to on December 13.Comment: 11pages, 7 figures, accepted for publication in MNRA
Geo-Metallurgical Studies of Rampura Agucha Deposit
Rampura Agucha deposit which is the 5 th largest deposit in the world in terms of the reserves and 3'd largest in terms of metal production, is also one of the most complex deposit in the world in terms of its textural characteri-stics, due to its highly deformed nature. The paper
details the results of Geo-metallurgical studies for identification of domains within the deposit with similar textural characteristics and their correlation with actual plant performance. As recovery performance of the valuable minerals directly impacts the profitability, the plant
metallurgist would be very much interested in improvement of recovery performance of lead / zinc and the inputs of process mineralogy for understanding metallurgical process are very important and the insights provided by process mineralogy in understanding and improving the recovery processes are described
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