21,461 research outputs found
Evidence for Compact Dark Matter in Galactic Halos
Clumped dark matter arises naturally within the framwork of generic
cosmological dark matter models. Invoking the existence of dark matter clumps
can also solve may unexplained mysteries in astrophysics and geology or
geophysics, eg. the galactic gamma-ray halo and the periodic terrestrial flood
basalt volcanic episodes. Clumped dark matter is dynamically stable to friction
and will not heat the disk. Such clumps may have already been discovered in the
form of dwarf spheroidals, and further searches are encouraged by the results
of this paper.Comment: Revised Version, includes new relevant references, Latex File, 16
pages, no figure
Two dimensional representation of the Dirac equation in Non associative algebra
In this note a simple extension of the complex algebra to higher dimension is
proposed. Using the postulated algebra a two dimensional Dirac equation is
formulated and its solution is calculated. It is found that there is a
sub-algebra where the associative nature can be recovered
Formal Solutions of a Class of Pfaffian Systems in Two Variables
In this paper, we present an algorithm which computes a fundamental matrix of
formal solutions of completely integrable Pfaffian systems with normal
crossings in two variables, based on (Barkatou, 1997). A first step was set in
(Barkatou-LeRoux, 2006) where the problem of rank reduction was tackled via the
approach of (Levelt, 1991). We give instead a Moser-based approach. And, as a
complementary step, we associate to our problem a system of ordinary linear
singular differential equations from which the formal invariants can be
efficiently derived via the package ISOLDE, implemented in the computer algebra
system Maple.Comment: Keywords: Linear systems of partial differential equations, Pfaffian
systems, Formal solutions, Moser-based reduction, Hukuhara- Turritin normal
for
Magnetohydrodynamic Viscous Flow Over a Shrinking Sheet With Second Order Slip Flow Model
In this paper, we investigate the magnetohydrodynamic viscous flow with
second order slip flow model over a permeable shrinking surface. We have
obtained the closed form of exact solution of Navier-Stokes equations by using
similarity variable technique. The effects of slip, suction and magnetic
parameter have been investigated in detail. The results show that there are two
solution branches, namely lower and upper solution branch. The behavior of
velocity and shear stress profiles for different values of slip, suction and
magnetic parameters has been discussed through graphs.Comment: 13 Pages, 8 Figures. Accepted for Publication in Heat Transfer
Researc
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