The use of protective clothing by motorcyclists in Victoria: Evaluation of the Community Policing and Education Project

The Community Policing and Education Project was launched by VicRoads and Victoria Police in 2009 to reduce the likelihood of motorcycle crashes through a combination of enforcement and education countermeasures. The Centre for Automotive Safety Research at the University of Adelaide was chosen to evaluate the effectiveness of the Project. Methods used to evaluate the Project included a process evaluation, analysis of crash data, on-road speed surveys, an online survey of motorcyclists, and roadside traffic observation. This paper provides an account of the roadside traffic observations, which were focused on helmet use, headlight use, use of protective clothing, and rider conspicuity. The roadside observations in metropolitan Melbourne revealed an apparent effect of the Project, with observed increases in the use of full body protection by motorcyclists following an educational operation targeting commuting riders. Across the three surveys, this proportion increased from 17 (before the operation) to 24 (just after the operation) to 38 per cent (three weeks after the operation). Improvement was most marked among riders of sports and standard/naked motorcycles but is still needed among riders of cruisers and scooters.Baldock, M. Kloeden, C. Lydon, M. Raftery, S. Grigo, J. & Ponte, G.http://acrs.org.au/events/acrs-past-conferences/2012-acrs-conference/program/papers/http://acrs.org.au/events/acrs-past-conferences/2012-acrs-conference

Asymmetric Primitive-Model Electrolytes: Debye-Huckel Theory, Criticality and Energy Bounds

Debye-Huckel (DH) theory is extended to treat two-component size- and charge-asymmetric primitive models, focussing primarily on the 1:1 additive hard-sphere electrolyte with, say, negative ion diameters, a--, larger than the positive ion diameters, a++. The treatment highlights the crucial importance of the charge-unbalanced ``border zones'' around each ion into which other ions of only one species may penetrate. Extensions of the DH approach which describe the border zones in a physically reasonable way are exact at high $T$ and low density, $\rho$, and, furthermore, are also in substantial agreement with recent simulation predictions for \emph{trends} in the critical parameters, $T_c$ and $\rho_c$, with increasing size asymmetry. Conversely, the simplest linear asymmetric DH description, which fails to account for physically expected behavior in the border zones at low $T$, can violate a new lower bound on the energy (which applies generally to models asymmetric in both charge and size). Other recent theories, including those based on the mean spherical approximation, have predicted trends in the critical parameters quite opposite to those established by the simulations.Comment: to appear in Physical Review

Density Fluctuations in an Electrolyte from Generalized Debye-Hueckel Theory

Near-critical thermodynamics in the hard-sphere (1,1) electrolyte is well described, at a classical level, by Debye-Hueckel (DH) theory with (+,-) ion pairing and dipolar-pair-ionic-fluid coupling. But DH-based theories do not address density fluctuations. Here density correlations are obtained by functional differentiation of DH theory generalized to {\it non}-uniform densities of various species. The correlation length $\xi$ diverges universally at low density $\rho$ as $(T\rho)^{-1/4}$ (correcting GMSA theory). When $\rho=\rho_c$ one has $\xi\approx\xi_0^+/t^{1/2}$ as $t\equiv(T-T_c)/T_c\to 0+$ where the amplitudes $\xi_0^+$ compare informatively with experimental data.Comment: 5 pages, REVTeX, 1 ps figure included with epsf. Minor changes, references added. Accepted for publication in Phys. Rev. Let

Mixing rates of particle systems with energy exchange

A fundamental problem of non-equilibrium statistical mechanics is the derivation of macroscopic transport equations in the hydrodynamic limit. The rigorous study of such limits requires detailed information about rates of convergence to equilibrium for finite sized systems. In this paper we consider the finite lattice $\{1, 2,..., N\}$, with an energy \EnergyStateI{i} \in (0,\infty) associated to each site. The energies evolve according to a Markov jump process with nearest neighbor interaction such that the total energy is preserved. We prove that for an entire class of such models the spectral gap of the generator of the Markov process scales as \Order(N^{-2}). Furthermore, we provide a complete classification of reversible stationary distributions of product type. We demonstrate that our results apply to models similar to the billiard lattice model considered in \cite{10297039,10863485}, and hence provide a first step in the derivation of a macroscopic heat equation for a microscopic stochastic evolution of mechanical origin