3,147 research outputs found
Quasi-Local Formulation of Non-Abelian Finite-Element Gauge Theory
Recently it was shown how to formulate the finite-element equations of motion
of a non-Abelian gauge theory, by gauging the free lattice difference
equations, and simultaneously determining the form of the gauge
transformations. In particular, the gauge-covariant field strength was
explicitly constructed, locally, in terms of a path ordered product of
exponentials (link operators). On the other hand, the Dirac and Yang-Mills
equations were nonlocal, involving sums over the entire prior lattice. Earlier,
Matsuyama had proposed a local Dirac equation constructed from just the
above-mentioned link operators. Here, we show how his scheme, which is closely
related to our earlier one, can be implemented for a non-Abelian gauge theory.
Although both Dirac and Yang-Mills equations are now local, the field strength
is not. The technique is illustrated with a direct calculation of the current
anomalies in two and four space-time dimensions. Unfortunately, unlike the
original finite-element proposal, this scheme is in general nonunitary.Comment: 19 pages, REVTeX, no figure
The effect of pre-exposure on family resemblance categorization for stimuli of varying levels of perceptual difficulty
This study investigated the effect that pre-exposure to a set of stimuli has on the prevalence of family resemblance categorization. 64 participants were tested to examine the effect that pre-exposure type (same-stimuli vs unrelated-stimuli) and the perceptual difficulty of the stimuli (perceptually similar vs perceptually different) has on categorization strategy. There was a significant effect of perceptual difficulty, indicating that perceptually different stimuli evoked a higher level of family resemblance sorting than perceptually similar stimuli. There was no significant main effect of pre-exposure type; however, there was a significant interaction between pre-exposure type and level of perceptual difficulty. Post-hoc tests revealed that this interaction was the result of an increase in family resemblance sorting for the perceptually different stimuli under relevant preexposure but no such effect for perceptually similar stimuli. The theoretical implications of these findings are discussed
Customer premise service study for 30/20 GHz satellite system
Satellite systems in which the space segment operates in the 30/20 GHz frequency band are defined and compared as to their potential for providing various types of communications services to customer premises and the economic and technical feasibility of doing so. Technical tasks performed include: market postulation, definition of the ground segment, definition of the space segment, definition of the integrated satellite system, service costs for satellite systems, sensitivity analysis, and critical technology. Based on an analysis of market data, a sufficiently large market for services is projected so as to make the system economically viable. A large market, and hence a high capacity satellite system, is found to be necessary to minimize service costs, i.e., economy of scale is found to hold. The wide bandwidth expected to be available in the 30/20 GHz band, along with frequency reuse which further increases the effective system bandwidth, makes possible the high capacity system. Extensive ground networking is required in most systems to both connect users into the system and to interconnect Earth stations to provide spatial diversity. Earth station spatial diversity is found to be a cost effective means of compensating the large fading encountered in the 30/20 GHz operating band
Matter in Toy Dynamical Geometries
One of the objectives of theories describing quantum dynamical geometry is to
compute expectation values of geometrical observables. The results of such
computations can be affected by whether or not matter is taken into account. It
is thus important to understand to what extent and to what effect matter can
affect dynamical geometries. Using a simple model, it is shown that matter can
effectively mold a geometry into an isotropic configuration. Implications for
"atomistic" models of quantum geometry are briefly discussed.Comment: 8 pages, 1 figure, paper presented at DICE 200
A truncation error model and its application to the accuracy analysis of constraint violations
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77162/1/AIAA-1993-3707-458.pd
Multiple Scattering: Dispersion, Temperature Dependence, and Annular Pistons
We review various applications of the multiple scattering approach to the
calculation of Casimir forces between separate bodies, including dispersion,
wedge geometries, annular pistons, and temperature dependence. Exact results
are obtained in many cases.Comment: 15 pages, 12 figures, contributed to the Festschrift for Emilio
Elizald
The Adler Function for Light Quarks in Analytic Perturbation Theory
The method of analytic perturbation theory, which avoids the problem of
ghost-pole type singularities and gives a self-consistent description of both
spacelike and timelike regions, is applied to describe the "light" Adler
function corresponding to the non-strange vector channel of the inclusive decay
of the lepton. The role of threshold effects is investigated. The
behavior of the quark-antiquark system near threshold is described by using a
new relativistic resummation factor. It is shown that the method proposed leads
to good agreement with the ``experimental'' Adler function down to the lowest
energy scale.Comment: 13 pages, one ps figure, REVTe
Direct mode summation for the Casimir energy of a solid ball
The Casimir energy of a solid ball placed in an infinite medium is calculated
by a direct frequency summation using the contour integration. It is assumed
that the permittivity and permeability of the ball and medium satisfy the
condition . Upon deriving the general
expression for the Casimir energy, a dilute compact ball is considered
. In this case the
calculations are carried out which are of the first order in and take
account of the five terms in the Debye expansion of the Bessel functions
involved. The implication of the obtained results to the attempts of explaining
the sonoluminescence via the Casimir effect is shortly discussed.Comment: REVTeX, 7 pages, no figures and tables, treatment of a dilute
dielectric ball is revised, new references are adde
An ecosystem characterisation of the Bay of Bengal
This study summarises the high level drivers on ecological systems of the BOBLME. The ecological characterisation resulted in the identification of 29 subsystems. The report recommends the development of fully integrated approaches that considers human needs and the ecological system, involving stakeholders in a transparent way
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