1,954 research outputs found
A conformal scalar dyon black hole solution
An exact solution of Einstein - Maxwell - conformal scalar field equations is
given, which is a black hole solution and has three parameters: scalar charge,
electric charge, and magnetic charge. Switching off the magnetic charge
parameter yields the solution given by Bekenstein. In addition the energy of
the conformal scalar dyon black hole is obtained.Comment: 7 pages, Late
Combinatorial Markov chains on linear extensions
We consider generalizations of Schuetzenberger's promotion operator on the
set L of linear extensions of a finite poset of size n. This gives rise to a
strongly connected graph on L. By assigning weights to the edges of the graph
in two different ways, we study two Markov chains, both of which are
irreducible. The stationary state of one gives rise to the uniform
distribution, whereas the weights of the stationary state of the other has a
nice product formula. This generalizes results by Hendricks on the Tsetlin
library, which corresponds to the case when the poset is the anti-chain and
hence L=S_n is the full symmetric group. We also provide explicit eigenvalues
of the transition matrix in general when the poset is a rooted forest. This is
shown by proving that the associated monoid is R-trivial and then using
Steinberg's extension of Brown's theory for Markov chains on left regular bands
to R-trivial monoids.Comment: 35 pages, more examples of promotion, rephrased the main theorems in
terms of discrete time Markov chain
Symmetric spaces of higher rank do not admit differentiable compactifications
Any nonpositively curved symmetric space admits a topological
compactification, namely the Hadamard compactification. For rank one spaces,
this topological compactification can be endowed with a differentiable
structure such that the action of the isometry group is differentiable.
Moreover, the restriction of the action on the boundary leads to a flat model
for some geometry (conformal, CR or quaternionic CR depending of the space).
One can ask whether such a differentiable compactification exists for higher
rank spaces, hopefully leading to some knew geometry to explore. In this paper
we answer negatively.Comment: 13 pages, to appear in Mathematische Annale
The Chemistry Of Aphids And Scale Insects
[No abstract available]4226328
Energy Distribution associated with Static Axisymmetric Solutions
This paper has been addressed to a very old but burning problem of energy in
General Relativity. We evaluate energy and momentum densities for the static
and axisymmetric solutions. This specializes to two metrics, i.e., Erez-Rosen
and the gamma metrics, belonging to the Weyl class. We apply four well-known
prescriptions of Einstein, Landau-Lifshitz, Papaterou and Mller to
compute energy-momentum density components. We obtain that these prescriptions
do not provide similar energy density, however momentum becomes constant in
each case. The results can be matched under particular boundary conditions.Comment: 18 pages, accepted for publication in Astrophysics and SpaceScienc
A two-cocycle on the group of symplectic diffeomorphisms
We investigate a two-cocycle on the group of symplectic diffeomorphisms of an
exact symplectic manifolds defined by Ismagilov, Losik, and Michor and
investigate its properties. We provide both vanishing and non-vanishing results
and applications to foliated symplectic bundles and to Hamiltonian actions of
finitely generated groups.Comment: 16 pages, no figure
Energy Distribution in f(R) Gravity
The well-known energy problem is discussed in f(R) theory of gravity. We use
the generalized Landau-Lifshitz energy-momentum complex in the framework of
metric f(R) gravity to evaluate the energy density of plane symmetric solutions
for some general f(R) models. In particular, this quantity is found for some
popular choices of f(R) models. The constant scalar curvature condition and the
stability condition for these models are also discussed. Further, we
investigate the energy distribution of cosmic string spacetime.Comment: 15 pages, accepted for publication in Gen. Relativ. & Gra
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Economic analysis of ethanol production from switchgrass using hybrid thermal/biological processing
The economics of ethanol production from switchgrass using Waterloo fast pyrolysis with a fermentation step is investigated. Standard chemical engineering methods are used to estimate capital investment and operating costs. Order of magnitude method is employed for preliminary approximation of capital investment. The azeotropic ethanol production capacity used in this case study is 189 million liters/year (50 million gallons/year). All cost figures are updated to 1997 US 142 million, while the annual operating cost is about 0.62/l (0.58/l (0.30 million/year, in order to meet the heat energy requirement of the process. Sensitivity analyses of feedstock cost and yield of sugar fermentation on the selling price of ethanol show that feedstock cost is positively related to ethanol selling price, while the yield has a negative relationship with selling price
Radiative processes (tau -> mu gamma, mu -> e gamma and muon g-2) as probes of ESSM/SO(10)
The Extended Supersymmetric Standard Model (ESSM), motivated on several
grounds, introduces two vectorlike families (16 + 16-bar) of SO(10)) with
masses of order one TeV. It is noted that the successful predictions of prior
work on fermion masses and mixings, based on MSSM embedded in SO(10), can be
retained rather simply within the ESSM extension. These include an
understanding of the smallness of V_{cb} ~ 0.04 and the largeness of nu_mu -
nu_tau oscillation angle, sin^2 2 theta_{nu_mu nu_tau}^{osc} ~ 1. We analyze
the new contributions arising through the exchange of the vectorlike families
of ESSM to radiative processes including tau -> mu gamma, mu -> e gamma, b -> s
gamma, EDM of the muon and the muon (g-2). We show that ESSM makes significant
contributions especially to the decays tau -> mu gamma and mu -> e gamma and
simultaneously to muon (g-2). For a large and plausible range of relevant
parameters, we obtain: a_mu^{ESSM} ~ +(10-40) times 10^{-10}, with a correlated
prediction that tau -> mu gamma should be discovered with an improvement in its
current limit by a factor of 3-20. The implications for mu -> e gamma are very
similar. The muon EDM is within reach of the next generation experiments. Thus,
ESSM with heavy leptons being lighter than about 700 GeV (say) can be probed
effectively by radiative processes before a direct search for these vectorlike
leptons and quarks is feasible at the LHC.Comment: 27 pages LaTex, 2 figure
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