N-version Design vs. One Good Version

Evidence indicates that n-version development techniques are more reliable than producing one "good" version-and cost effective in the long run. The author concludes that diverse, independent channels used in parallel are significantly superior to even the current state of the art, especially in situations where cost of failure is high

RAS Project Evaluative Report

Report findings from university study RAS (Retain, Achieve, Succeed), a staff research programme that examines issues around a 30% achievement gap between home black and home white students. Its focus has been on the curriculum and understanding matters of diversity and accessibility within institutional delivery at UAL

Compositional controls on melting and dissolving a salt into a ternary melt

We explore theoretically the controls on dissolution of salt A, in an undersaturated brine of salts A and B. We show that, as the concentration of B increases, the dissolution rate of A decreases, for brine of given temperature. We also show that there is a sharper decrease in dissolution rate with increasing concentration, for concentrations of B above a critical value, where B limits the equilibrium concentration. We explore the implications of the predictions for dissolution of KCl or NaCl, by a mixed brine of NaCl and KCl, a common reaction that may arise in dissolution of evaporites. We predict that, with mixed-composition brine, KCl crystals dissolve more rapidly than NaCl crystals, unless the (far-field) brine is nearly saturated in KCl. We also predict that the dissolution rate of these salts is largely independent of fluid temperature and is controlled by compositional diffusion

Improving the Catchment through Market Based Instruments

In this paper, six potential MBIs are discussed that have potential for improving environmental outcomes.Australia;water;urban water;market based instruments

The Economics of Water: Taking Full Account of First Use, Reuse and Return to the Environment.A Report for the Australian Water Conservation and Reuse Research Program (AWCRRP).

There has been a lot of discussion about water being undervalued in Australia. The nation's attention is presently focussed on water issues with the drought of 2002 - 2003, the deepening crisis with the River Murray and water rationing in a number of urban areas. Over 2003-2005, the States and Territories will be required to demonstrate progress against the water reform goals in the area of urban and rural water pricing. This is an opportune time as part of the Australian Water Conservation and Reuse Research Program to develop a framework for the introduction of mechanisms that reveal the full cost of using water. This paper emphasises the importance of looking at potable water, reuse and disposal and return of water to the environment together as part of a comprehensive framework.catchment; Australia; water; water reuse

Diffusion-controlled dissolution of a binary solid into a ternary liquid with partially-molten zone formation

We build a theoretical model of equilibrium dissolution of a homogeneous, solid mixture of two salts A and B, KCl and NaCl being used as the type example, into an aqueous solution of the two salts, with diffusive transport. We find that there are two sharp dissolution fronts, separating fluid, a partially molten zone containing a single solid and mixed solid. The phase change happens almost entirely at the two sharp fronts. In equilibrium, the leading front exhibits a small amount of precipitation of NaCl, simultaneous with complete dissolution of KCl. There is a unique surface in the space of far-field fluid KCl concentration, far-field fluid NaCl concentration and solid composition, dividing conditions where NaCl is the solid in the partially molten zone, from conditions where KCl is the solid in the partially molten zone. The movement rates of the dissolution fronts decrease as the concentration of either salt in the far-field fluid is increased. The movement rates of the dissolution fronts increase as either far-field temperature is increased, but this effect is smaller than that of concentration. In most circumstances, the dissolution front for a given salt moves more slowly, the more of that salt is present in the original solid, although the mass dissolution rate is not greatly affected by the solid composition

Modelling the redshift-space distortion of galaxy clustering

We use a set of large, high-resolution cosmological N-body simulations to examine the redshift-space distortions of galaxy clustering on scales of order 10-200h^{-1} Mpc. Galaxy redshift surveys currently in progress will, on completion, allow us to measure the quadrupole distortion in the 2-point correlation function, \xi(\sigma,\pi), or its Fourier transform, the power spectrum, P(k,\mu), to a high degree of accuracy. On these scales we typically find a positive quadrupole, as expected for coherent infall onto overdense regions and outflow from underdense regions, but the distortion is substantially weaker than that predicted by pure linear theory. We assess two models that may be regarded as refinements to linear theory, the Zel'dovich approximation and a dispersion model in which the non-linear velocities generated by the formation of virialized groups and clusters are treated as random perturbations to the velocities predicted by linear theory. We find that neither provides an adequate physical description of the clustering pattern. If used to model redshift spacedistortions on scales for 10<\lambda <200 h^{-1}Mpc the estimated value of \beta (\beta=f(\Omega_0)/b where f(\Omega_0) ~ \Omega_0^{0.6} and b is the galaxy bias parameter) is liable to systematic errors of order ten per cent or more. We discuss how such systematics can be avoided by i) development of a more complete model of redshift distortions and ii) the direct use of galaxy catalogues generated from non-linear N-body simulations.Comment: 13 pages, Latex, uses mn.sty and mnextra.sty (mnextra.sty included here

The Cliometrics of International Migration: A Survey

This is a survey of some of the key studies in the literature on international migration in history that may be described as cliometric. This literature uses the concepts and approaches of applied economics to investigate a range of historical issues and there are strong parallels with the questions that have been addressed in the literature on contemporary migrations. Here I focus on the period 1850 to 1940 and chiefly on migration from Europe to the New World. The survey is organised around six themes that include: the forces driving migration, over time and across space; the assimilation of migrants and their effects on wages and income distribution in source and destination countries; and the evolution of immigration policy. While this literature has drawn heavily on the tool kit of applied economists it also provides a wider perspective on many of the issues that concern migration today.international migration, economic history