Thesis (Ph. D.)--Florida State University, 2006. / Advisor: Kirby Kemper, Florida State University, College of Arts and Sciences, Dept. of Physics. Title and description from dissertation home page (viewed Sept. 21, 2006). Document formatted into pages; contains x, 124 pages. Includes bibliographical references.

Zugl.: Siegen, Universiẗat, Diss., 2004.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 227-234). Also available on the World Wide Web.

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

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Maize (Zea mays L.) is grown in a wide range of environments and altitudes worldwide. Maize has transitioned from open pollinated varieties to single cross hybrids over the last century. While maize production and genetic gain has increased, genetic diversity among U.S. maize hybrids has narrowed. Problems, such as insect pressure, diseases, and mycotoxins, present obstacles for breeders. One approach is to use exotic germplasm in breeding programs to provide useful, novel alleles for productivity, grain quality, and disease resistance. Little exotic germplasm has been used, because of lack of agronomic adaptation and problems with lodging, earliness, and tall plants in more temperate areas. Using exotic elite materials and evaluating them in targeted regions might increase success. Objectives of this research were: to characterize and evaluate agronomic adaptation and performance of Argentine commercial hybrids in the U.S., to evaluate semi-exotic testcrosses developed from semi adapted 100% tropical lines and elite U.S. inbred LH195, and to estimate response to aflatoxin contamination of Argentine hybrids and semi-exotic testcrosses under inoculation with Aspergillus flavus. Agronomic data was collected during 2004 in eleven Texas environments for Argentine hybrids, and eight Texas environments for semi-exotic testcrosses. Response to aflatoxin was measured in three southern Texas environments. U.S. commercial hybrids were used as checks. Significant differences among hybrids were observed for most environments and traits. In general, Argentine hybrids yielded lower, had lower 1000 kernel weights, and greater test weights than U.S. hybrids. Hybrids AX889, AX882MG, and AX890MG were competitive with U.S. hybrids for grain yield and were stable across environments. Semi-exotic testcrosses had similar lodging and grain moisture percentages, heavier test weights and competitive grain yields compared with U.S. hybrids. Hybrid TX-LAMA2002-9-2-B/lH195 had the highest overall grain yield mean for semi-exotic testcrosses and yielded better than two U.S. hybrids. Argentine hybrids had lower aflatoxin concentration than U.S. hybrids; several hybrids had less than 50 ng g-1 aflatoxin. Semi-exotic testcrosses had reduced aflatoxin compared to U.S. hybrids, with several hybrids under 35 ng g-1. These elite, exotic materials show promise for breeding programs, with competitiveness for grain yield, kernel traits, and reduced aflatoxin levels.

“Exotic-type” Cu silicate-oxide deposits hosted by Miocene pediment gravels represent an unusual, but characteristic, by-product of the supergene enrichment of Cenozoic porphyry Cu deposits in northern Chile. Carbon stable isotopic analysis is employed herein to clarify the environment of exotic ore formation and to provide guidelines for the exploration for non-outcropping mineralisation. Two main sample suites were examined: chrysocolla-rich ores from the Huinquintipa and Mina Sur deposits; and soils overlying a paleochannel in the Huinquintipa area known to be mineralised. The samples were processed using four different analytical techniques to determine their 13C values: (1) Elemental Analysis Isotope Ratio Mass Spectrometry (EA/IRMS) of the whole sample; (2) crushing in vacuo followed by IRMS to analyse fluid inclusions; (3) thermal extraction at 100˚C, followed by IRMS to analyse weakly bound carbon dioxide; and (4) ethylenediaminetetraacetic acid (EDTA) extraction followed by IRMS. EDTA-partial extraction favours the dissolution of minerals with divalent cations, releasing as carbon dioxide the carbon trapped within the crystal structure. All four of these analytical techniques have been used before, but this is the first time that they have all been used together on exotic copper silicate and oxide mineralisation. Three major carbon sources are identified: (1) atmosphere-derived carbon dioxide with a 13C value of around 0 ‰; (2) plant-derived carbon dioxide with a 13C of about -25 ‰; and (3) microbe-derived carbon dioxide with a 13C of approximately -50 ‰. The bulk of the carbon liberated by EA/IRMS was plant-derived. The thermally- and crushing-released carbon dioxide has the highest proportion of atmosphere-derived carbon, whereas EDTA-extraction preferentially liberated the lightest of carbon. On the conclusion that EDTA preferentially dissolved Cu-rich silicate mineraloids, it is concluded that microbial consortia, including methanogenic microbes, were hosted specifically by the high-grade Cu assemblages and plausibly played a critical role in their precipitation. The same microbial-carbon signature was obtained through the EDTA-extraction of soil samples above the paleochannel. Carbon isotopic analysis of CO2 sequestered through EDTA-extraction could therefore be used as an exploration tool for buried exotic mineralisation. Future exploration should exploit the presence of microbes in niche-specific environments. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2007-12-19 15:43:17.198 / Anglo American plc

No description available.

Thesis (Ph. D.)--Michigan State University. Dept. of Physics and Astronomy, 2006. / Title from PDF t.p. (viewed on Nov. 20, 2008) Includes bibliographical references (p. 124-130). Also issued in print.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [98]-113).