On zero-divisors in group rings of groups with torsion

Nontrivial pairs of zero-divisors in group rings are introduced and discussed. A problem on the existence of nontrivial pairs of zero-divisors in group rings of free Burnside groups of odd exponent $n \gg 1$ is solved in the affirmative. Nontrivial pairs of zero-divisors are also found in group rings of free products of groups with torsion.Comment: 8 pages, to appear in Canadian Math. Bul

Regeneration Of Diesel Particulate Filters With Hydrogen Rich Gas

The options for the regeneration of a Diesel Particulate Filter (DPF) using hydrogen rich gas are investigated. The advantages of using hydrogen rich gas for this purpose are described. The system requirements for such a system are also evaluated. The use of a plasmatron fuel converter for the onboard generation of hydrogen rich gas from diesel fuel is discussed. The advantages of homogeneous, non-catalytic reforming by the plasmatron fuel converter are described. Finally, the effect of homogeneous combustion of the hydrogen rich gas in the exhaust (upstream from the DPF) is investigated. I

Arguments prove nothing unless verified. A commentary on Kaufman's “Epidemiologic analysis of racial/ethnic disparities: Some fundamental issues and a cautionary example”

http://dx.doi.org/10.1016/j.socscimed.2007.11.04

ICarbS, Volume 5, Issue 1

Contents Mordecai Gorelik: A Scholar and Writer Who Addresses Humanity by Christian H. Moe / 3 Mordecai Gorelik\u27s Scenic Imagination: Antecedents and Consequences by Marie J. Kilker / 17 Jean Cocteau\u27s Doodling by Genevieve Fremont & David L. Gobert / 25 Chamber Music: Words by Joyce, Music by Molyneux Palmer by Myra Russel / 31 Son of a Burke : The Hugh Dalziel Duncan Collection at Morris Library by Charles Elkins / 45 Passages in the Life of Reginald Hunter by Kenneth Hopkins / 61 Contributors / 75 Illustrations Clifford Odets\u27s Golden Boy, 1937 / 6 Moredecai Gorelik\u27s set design for Desire Under the Elms / 10 Gorelik\u27s set design for God, Man, and Devil, Act II / 18 Design for spider web, Volpone / 22 Cocteau\u27s doodling / 28 Composer Geoffrey Molyneux Palmer / 30 Score for Chamber Music poem XXVIII, Gentle Lady / 34-35 Score for poem XXXI, O, it was out by Donnycarney / 38-39 Hugh Dalziel Duncan, 1962 / 48 Kenneth Burke and wife Libby, 1946 / 52 Molyneux Palmer score for James Joyce poem / Cove

Factorizations of Elements in Noncommutative Rings: A Survey

We survey results on factorizations of non zero-divisors into atoms (irreducible elements) in noncommutative rings. The point of view in this survey is motivated by the commutative theory of non-unique factorizations. Topics covered include unique factorization up to order and similarity, 2-firs, and modular LCM domains, as well as UFRs and UFDs in the sense of Chatters and Jordan and generalizations thereof. We recall arithmetical invariants for the study of non-unique factorizations, and give transfer results for arithmetical invariants in matrix rings, rings of triangular matrices, and classical maximal orders as well as classical hereditary orders in central simple algebras over global fields.Comment: 50 pages, comments welcom

Activated and quantum creep of the charge-density waves in magnetic field in {\it o}-TaS3_3

We demonstrate that magnetoresistance of creeping charge-density waves in the quasi-one dimensional conductor {\it o}-TaS$_3$ changes its character from a negative parabolic at $T\gtrsim 10$ K where it obeys $1/T^2$ law to a weakly temperature dependent negative nearly linear one at lower temperatures. The dominant contribution into the negative parabolic magnetoresistance comes from magnetic field induced splitting of the CDW order parameter. The linear magnetoresistance arises due to CDW quantum interference similar to the scenario of negative linear magnetoresistance in single-electron systems.Comment: 8 pages, 10 figure

Uncertainty Management for Rule-Based Decision Support Systems

We present an uncertainty management scheme in rule-based systems for decision making in the domain of urban infrastructure. Our aim is to help end users make informed decisions. Human reasoning is prone to a certain degree of uncertainty but domain experts frequently find it difficult to quantify this precisely, and thus prefer to use qualitative (rather than quantitative) confidence levels to support their reasoning. Secondly, there is uncertainty in data when it is not currently available (missing). In order to incorporate human-like reasoning within rule-based systems we use qualitative confidence levels chosen by domain experts in urban infrastructure. We introduce a mechanism for the representation of confidence of input facts and inference rules, and for the computation of confidence in the inferred facts. We also present a mechanism for computing inferences in the presence of missing facts, and their effect on the confidence of inferred facts

ICarbS, Volume 3, Issue 2

Contents A Note on Hal Trovillion and the Powys Brothers by Kenneth Hopkins / 89 Harry Crosby, His Death, His Diaries by Edward B. Germain / 103 Harry Crosby\u27s Sun Code by Sasha Newborn / 111 The Crosbys: An Afterword by Kay Boyle / 117 The Later Caresse Crosby: Her Answer Remained Yes by Harry T. Moore / 127 A Letter from Voltaire by Henry Vyverberg / 135 Masters Works on Toward the Gulf by Herb Russell / 149 The Southern illinois University Library: A Century of Growth and Service by Kenneth G. Peterson / 152 Contributors / 166 Illustrations John Cowper Powys and Violet Trovillion, 1938 / 96 Pastel of Harry Crosby by Bradford Johnson, ca. 1923 / 102 Pastel of Caresse Crosby by Bradford Johnson, ca. 1923 / 104 Kay Boyle and Harry Crosby at LeMoulin du Soleil,. 1927 / 118 Caresse Crosby by Manuel Angeles Ortiz, 1928 / 126 Ezra Pound and Caresse Crosby, the 1960s / 132 Voltaire a.l.s., 14 April1754, to Father Joseph de Menoux / 142-144 Wheeler Library reading room, 1904 / 152 Flutes and Bones by Romare Bearden / Cove

Chandra X-ray Sources in the Collapsed-Core Globular Cluster M30 (NGC 7099)

We report the detection of six discrete, low-luminosity (Lx < 10^33 erg/s) X-ray sources, located within 12 arcsec of the center of the collapsed-core globular cluster M30 (NGC 7099), and a total of 13 sources within the half-mass radius, from a 50 ksec Chandra ACIS-S exposure. Three sources lie within the very small upper limit of 1.9 arcsec on the core radius. The brightest of the three core sources has a luminosity of Lx (0.5-6 keV) = 6x10^32 erg/s and a blackbody-like soft X-ray spectrum, which are both consistent with it being a quiescent low-mass X-ray binary (qLMXB). We have identified optical counterparts to four of the six central sources and a number of the outlying sources, using deep Hubble Space Telescope and ground-based imaging. While the two proposed counterparts that lie within the core may represent chance superpositions, the two identified central sources that lie outside of the core have X-ray and optical properties consistent with being CVs. Two additional sources outside of the core have possible active binary counterparts. We discuss the X-ray source population of M30 in light of its collapsed-core status.Comment: 18 pages, 13 figures (8 color), resubmitted to ApJ after incorporating referee comment