31,916 research outputs found
The role of the equation of state and the space-time dimension in spherical collapse
We study the spherically symmetric collapse of a fluid with non-vanishing
radial pressure in higher dimensional space-time. We obtain the general exact
solution in the closed form for the equation of state ()
which leads to the explicit construction of the root equation governing the
nature (black hole versus naked singularity) of the central singularity. A
remarkable feature of the root equation is its invariance for the three cases:
(),
() and () where is the
dimension of space-time. That is, for the ultimate end result of the collapse,
-dimensional dust, - AdS (anti de Sitter)-like and - dS-like
are absolutely equivalent.Comment: 4 Pages, RevTeX, no figures, minor changes, new references added,
Detailed version to follo
Planar Two-particle Coulomb Interaction: Classical and Quantum Aspects
The classical and quantum aspects of planar Coulomb interactions have been
studied in detail. In the classical scenario, Action Angle Variables are
introduced to handle relativistic corrections, in the scheme of
time-independent perturbation theory. Complications arising due to the
logarithmic nature of the potential are pointed out. In the quantum case,
harmonic oscillator approximations are considered and effects of the
perturbations on the excited (oscillator) states have been analysed. In both
the above cases, the known 3+1-dimensional analysis is carried through side by
side, for a comparison with the 2+1-dimensional (planar) results.Comment: LaTex, Figures on request, e-mail:<[email protected]
Non-spherical collapse of a two fluid star
We obtain the analogue of collapsing Vaidya-like solution to include both a
null fluid and a string fluid, with a linear equation of state (), in non-spherical (plane symmetric and cylindrically symmetric) anti-de
Sitter space-timess. It turns out that the non-spherical collapse of two fluid
in anti-de Sitter space-times, in accordance with cosmic censorship, proceed to
form black holes, i.e., on naked singularity ever forms, violating hoop
conjecture.Comment: 7 pages, RevTeX 4, minor correction
Psychological Morbidity in Students of Medical College and Science and Art College Students - A Comparative Study
Considering the importance of quality of life in medical students we have conducted a cross sectional & descriptive study on screening of mental illness of 60 medical students of prefinal year and comparing it with 60 students of third year of Science and Art College. Students were selected via random sampling. GHQ-12 was used as a screening tool and after obtaining scores students were graded in 3 categories - individuals screened positive for psychological morbidity were of Grades 2 and 3 and individuals screened negative for psychological morbidity were of Grade 1 and they were compared according to college, gender & residence. Students screened positive for psychological morbidity as per GHQ-12 were found higher in medical college (87%) as compared to Science and Art College (45%) and a statistically significant association was found between psychological morbidity and medical students. Psychological morbidity was not significantly associated with residence and gender
Response of strongly-interacting matter to magnetic field: some exact results
We derive some exact results concerning the response of strongly-interacting
matter to external magnetic fields. Our results come from consideration of
triangle anomalies in medium. First, we define an "axial magnetic
susceptibility," then we examine its beahvior in two flavor QCD via response
theory. In the chirally restored phase, this quantity is proportional to the
fermion chemical potential, while in the phase of broken chiral symmetry it can
be related, through triangle anomalies, to an in-medium amplitude for the
neutral pion to decay to two photons. We confirm the latter result by
calculation in a linear sigma model, where this amplitude is already known in
the literature.Comment: 13 pages, no figures, To be submitted to Physical Review D, fixed an
omitted referenc
Non-marginally bound inhomogeneous dust collapse in higher dimensional space-time
We investigate the occurrence and nature of a naked singularity in the
gravitational collapse of an inhomogeneous dust cloud described by a
self-similar higher dimensional Tolman-Bondi space-time. Bound, marginally
bound and unbound space-times are analyzed. The degree of inhomogeneity of the
collapsing matter necessary to form a naked singularity is given.Comment: 5 pages, RevTeX 4, no figures, 2 tables, Accepted in IJMP
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