A Supplement to the Classification of Flat Homogeneous Spaces of Signature (m,2)

Duncan and Ihrig (1993) gave a classification of the flat homogeneous spaces of metric signature (m,2), provided that a certain condition on the development image of these spaces holds. In this note we show that this condition can be dropped, so that Duncan and Ihrig's classification is in fact the full classification for signature (m,2).Comment: shortened, one reference added, fixed typo

President-Elect Obama’s Choice for Secretary of Education: Arne Duncan

Tuesday, December 16, President-elect Obama announced his choice for Secretary of Education: Arne Duncan

Effects of heat exposure and volumetric compression on Poisson's ratios, Young's moduli and polymeric composition during thermo-mechanical conversion of auxetic open cell polyurethane foam

The effects of thermo-mechanical auxetic foam conversion parameters on the Young's modulus and Poisson's ratio of open-cell polyurethane foam are related to changes in chemical bonding and cell structure. Applied volumetric compression, conversion temperature and duration are reported on foam Young's modulus, Poisson's ratio and structural stability. Fourier transform infrared spectral analysis on samples converted at and above 160°C strongly indicates a hydrogen bond interaction increase in urea groups (C=O---H-N) and an increase in hydrogen bonding population. Spectral changes inferred soft segment degradation following extensive heat exposure (200°C, 180 minutes), specifically a shift and intensity change in CH2 and C-O-C polyol bands and a broad baseline increase between 3600 and 2400 cm-1. These changes are linked to: i) resistance to dimensional recovery over time and during re-heating, ii) Poisson's ratio becoming negative, then zero in tension or marginally positive in compression, iii) Young's Modulus reducing then increasing, iv) mass loss, evidenced by thermogravimetric analysis increasing from 150°C. The minimum mean values of Poisson's ratio of ~-0.2 (to 10% compression/tension) are comparable to other studies. All samples that retain their imposed compression over time are isotropic, with near constant Young's moduli and Poisson's ratio (to 10 % compression/tension)

Recent results using all-point quark propagators

Pseudofermion methods for extracting all-point quark propagators are reviewed, with special emphasis on techniques for reducing or eliminating autocorrelations induced by low eigenmodes of the quark Dirac operator. Recent applications, including high statistics evaluations of hadronic current correlators and the pion form factor, are also described.Comment: LateX, 3 pages, 6 eps figures, Lattice2002(algor), corrected some typo

\u3cem\u3eLegacy of Courage: Calgary’s Own 137th Battalion\u3c/em\u3e by Fred Bagley and Dr. H.D. Duncan [Review]

Review of Fred Bagley & Dr. Harvey Daniel Duncan, A Legacy of Courage: Calgary\u27s Own 137th Overseas Battalion, CEF. Calgary: Pulp Street Books, 1994

Activism, Fly Fishing, and Fiction: A Conversation with David James Duncan

This interview with David James Duncan is part of a series of conversations with contemporary western writers about the ethical and cultural implications of nature writing

Living Green Is a Lifestyle Choice

Duncan Reid \u2710 is dedicated to living a sustainable lifestyle. He\u27s made his mark on campus and with students, professors, and administrators, for his dedication to the environment

Unquenched Studies Using the Truncated Determinant Algorithm

A truncated determinant algorithm is used to study the physical effects of the quark eigenmodes associated with eigenvalues below 420 MeV. This initial high statistics study focuses on coarse ($6^4$) lattices (with O($a^2$) improved gauge action), light internal quark masses and large physical volumes. Three features of full QCD are examined: topological charge distributions, string breaking as observed in the static energy and the eta prime mass.Comment: Lattice2001(confinement); 3pgs(Latex), 4figs.(ps