9,181 research outputs found
Covariant Phase Space Formulations of Superparticles and Supersymmetric WZW Models
We present new covariant phase space formulations of superparticles moving on
a group manifold, deriving the fundamental Poisson brackets and current
algebras. We show how these formulations naturally generalise to the
supersymmetric Wess-Zumino-Witten models.Comment: 15pp., LaTe
Hamiltonian Reduction and Supersymmetric Toda Models
New formulations of the solutions of N=1 and N=2 super Toda field theory are
introduced, using Hamiltonian Reduction of the N=1 and N=2 super WZNW Models to
the super Toda Models. These parameterisations are then used to present the
Hamiltonian formulations of the super Toda theories on the spaces of solutions.Comment: 15pp., LaTe
The Solutions of Affine and Conformal Affine Toda Field Theories
We give new formulations of the solutions of the field equations of the
affine Toda and conformal affine Toda theories on a cylinder and
two-dimensional Minkowski space-time. These solutions are parameterised in
terms of initial data and the resulting covariant phase spaces are
diffeomorphic to the Hamiltonian ones. We derive the fundamental Poisson
brackets of the parameters of the solutions and give the general static
solutions for the affine theory.Comment: 11pp, phyzz
Primary connections in a provincial Queensland school system: relationships to science teaching self-efficacy and practices
The teaching of science is important, both to meet the need for future workers in fields requiring scientific capability and to equip students for full participation in modern societies where many decisions depend upon knowledge of science. However, many teachers in Australian primary schools do not allocate science education sufficient amounts of time to achieve these outcomes. This study reports data obtained from 216 teachers in the primary schools in a provincial Australian school system. The purpose of the study was to assess the effects of existing strategies using Primary Connections for promoting science teaching and to inform future professional development strategies. Teachers reported moderate levels of self-efficacy for teaching science and a proportion reported allocating little or no time to teaching science. Both self-efficacy for science teaching and the amount of science taught were higher for teachers who had used Primary Connections curriculum materials
Contributions of the low-latitude boundary layer to the finite width magnetotail convection model
Convection of plasma within the terrestrial nightside plasma sheet contributes to the structure and, possibly, the dynamical evolution of the magnetotail. In order to characterize the steady state convection process, we have extended the finite tail width model of magnetotail plasma sheet convection. The model assumes uniform plasma sources and accounts for both the duskward gradient/curvature drift and the earthward E × B drift of ions in a two-dimensional magnetic geometry. During periods of slow convection (i.e., when the cross-tail electric potential energy is small relative to the source plasma\u27s thermal energy), there is a significant net duskward displacement of the pressure-bearing ions. The electrons are assumed to be cold, and we argue that this assumption is appropriate for plasma sheet parameters. We generalize solutions previously obtained along the midnight meridian to describe the variation of the plasma pressure and number density across the width of the tail. For a uniform deep-tail source of particles, the plasma pressure and number density are unrealistically low along the near-tail dawn flank. We therefore add a secondary source of plasma originating from the dawnside low-latitude boundary layer (LLBL). The dual plasma sources contribute to the plasma pressure and number density throughout the magnetic equatorial plane. Model results indicate that the LLBL may be a significant source of near-tail central plasma sheet plasma during periods of weak convection. The model predicts a cross-tail pressure gradient from dawn to dusk in the near magnetotail. We suggest that the plasma pressure gradient is balanced in part by an oppositely directed magnetic pressure gradient for which there is observational evidence. Finally, the pressure to number density ratio is used to define the plasma “temperature.” We stress that such quantities as temperature and polytropic index must be interpreted with care as they lose their nominal physical significance in regions where the two-source plasmas intermix appreciably and the distributions become non-Maxwellian
On the possibility of quasi-static convection in the quiet magnetotail
Abstract
The magnetotail is known to serve as a reservoir of energy transferred into the terrestrial magnetosphere from the solar wind. In principle, the stored energy can be dissipated impulsively, as in a substorm, or steadily through the process of steady adiabatic plasma convection. However, some theoretical arguments have suggested that quasi-static adiabatic convection cannot occur throughout the magnetotail because of the structure of the magnetic field. Here we reexamine the question. We show that in a magnetotail of finite width, downtail pressure gradients depend strongly on the ratio of the potential across half the tail to the ion temperature in the far tail (60 RE). For pertinent quiet time ratios (∼3), a Tsyganenko quiet-time magnetic field model is consistent with steady convection
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