Black hole singularities: a numerical approach

The singularity structure of charged spherical collapse is studied by considering the evolution of the gravity-scalar field system. A detailed examination of the geometry at late times strongly suggests the validity of the mass-inflation scenario~\cite{PI:90}. Although the area of the two-spheres remains finite at the Cauchy horizon, its generators are eventually focused to zero radius. Thus the null, mass-inflation singularity {\em generally}\/ precedes a crushing $r=0$ singularity deep inside the black hole core. This central singularity is spacelike.Comment: 4 pages Phys. Rev. style including five figures, provided as compressed postscript files. To appear in Physical Review Letter

Heats of formation of bcc binary alloys

The method of Bozzolo, Ferrante and Smith is applied for the calculation of alloy energies for bcc elements. The heat of formation of several alloys is computed with the help of the Connolly-Williams method within the tetrahedron approximation. The dependence of the results on the choice of different sets of ordered structures is discussed

Community Response to Forestry Transition in Rural Canada: Analysis of Media and Census Data for Six Case Study Communities in New Brunswick and British Columbia

The forest economy is in transition across Canada. Faced with high dollar values, increasing competition within the global market, high input costs for energy, labour and fibre, and growing expectations for environmental performance, the forest sector is undergoing significant economic transitions as companies across the country cut costs, close mills and shed jobs. This report contributes to our understanding of community response to mill closure with a detailed description of six case study communities during a period of forest industry mill closures. Three communities are in British Columbia (Mackenzie, Quesnel and Fort St. James) and three communities are in New Brunswick (Dalhousie, Nackawic and Mirimachi). Empirical information is derived from national and local media reports as well as recent data from the Census of Canada. Key thematic areas include resilience, economic diversification, the nature of mill closure, union involvement, government involvement and concerns over government policy changes such as appurtenancy.media analysis, rural sociology, community development, rural development, social change, Community/Rural/Urban Development, R52, R58, Q33,

Student understanding of the Boltzmann factor

We present results of our investigation into student understanding of the physical significance and utility of the Boltzmann factor in several simple models. We identify various justifications, both correct and incorrect, that students use when answering written questions that require application of the Boltzmann factor. Results from written data as well as teaching interviews suggest that many students can neither recognize situations in which the Boltzmann factor is applicable, nor articulate the physical significance of the Boltzmann factor as an expression for multiplicity, a fundamental quantity of statistical mechanics. The specific student difficulties seen in the written data led us to develop a guided-inquiry tutorial activity, centered around the derivation of the Boltzmann factor, for use in undergraduate statistical mechanics courses. We report on the development process of our tutorial, including data from teaching interviews and classroom observations on student discussions about the Boltzmann factor and its derivation during the tutorial development process. This additional information informed modifications that improved students' abilities to complete the tutorial during the allowed class time without sacrificing the effectiveness as we have measured it. These data also show an increase in students' appreciation of the origin and significance of the Boltzmann factor during the student discussions. Our findings provide evidence that working in groups to better understand the physical origins of the canonical probability distribution helps students gain a better understanding of when the Boltzmann factor is applicable and how to use it appropriately in answering relevant questions

Ages and metallicities of faint red galaxies in the Shapley Supercluster

We present results on the stellar populations of 232 quiescent galaxies in the Shapley Supercluster, based on spectroscopy from the AAOmega spectrograph at the AAT. The key characteristic of this survey is its coverage of many low-luminosity objects (sigma ~ 50 km/s), with high signal-to-noise (~45 per Angstrom). Balmer-line age estimates are recovered with ~25% precision even for the faintest sample members. We summarize the observations and absorption line data, and present correlations of derived ages and metallicities with mass and luminosity. We highlight the strong correlation between age and alpha-element abundance ratio, and the anti-correlation of age and metallicity at fixed mass, which is shown to extend into the low-luminosity regime.Comment: Four pages, three figures; To appear in Proceedings of IAU Symp. 245 "Formation and Evolution of Galaxy Bulges", (Oxford, July 16-20 2007), Eds. Martin Bureau, Lia Athanassoula, and Beatriz Barbu