Abstract¡G We measured time-resolved PL of Zn1-XCdXSe epilayer and ZnSe/Zn0.91Cd0.09Se MQW by Upconversion experiment. The Zn1-XCdXSe epilayer was growth with four kind of Cadmium compositions (X=0.08¡B0.32¡B0.60 and 0.84). The thickness of the Zn1-XCdXSe epilayer is around 0.5£gm. The ZnSe/Zn0.91Cd0.09Se MQW of well width thickness varies from 5nm¡B10nm¡B15nm to 20nm . From carrier recombination mechanism ,We get the two sample relative temperature dependence of radiative¡Bnonradiative recombination lifetime and quantum efficiency , From nonradiative recombination lifetime formula , we can get trap concentration and capture cross section. At low temperature the two samples recombination process is dominated by radiative recombination process. The two samples increase nonradiative recombination process and decrease quantum efficiency with increasing temperature. At high temperature the two samples recombination process is dominated by nonradiative recombination process.

Thesis (Ph. D.)--University of Chicago, Dept. of Molecular Genetics and Cell Biology, 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.)--Brown University, 2008. / Vita. Advisor : Arthur Landy. Includes bibliographical references.

Thesis (Ph. D.)--York University, 1999. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 116-143). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ39313.

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Lineages of the cyanobacteria Prochlorococcus marinus have diverged into two genetically distinct ‘ecotypes,’ high-light adapted (HL) and low-light adapted (LL), which thrive under different environmental conditions. This type of niche differentiation in prokaryotes is often accompanied by genetic and genomic divergence. Differential selection pressure associated with ecotype divergence can be analyzed using models of codon evolution. However, some characteristics of the Prochlorococcus genome violate underlying assumptions of these models. For example, high levels of recombination between bacterial strains are known to cause false positives for codon models. Therefore, it is important that statistical methods for detecting recombination be reliable. In Chapter 2, I evaluate a set of recombination detection methods under four different scenarios related to functional divergence: 1) varying tree shape, 2) positive selection, 3) non-stationary evolution, and 4) varying levels of recombination and divergence.

Homologous recombination (HR) is a precise mechanism for repairing harmful DNA double-strand breaks. The process has been extensively studied in microbial species leading to identification of the major proteins, HR models and homology requirements. Much less is known about HR in mammalian systems, especially early HR events. Our laboratory has recently devel-oped an assay that detects the new DNA synthesis that accompanies the early homology search and strand invasion steps of HR (the 3’ extension assay). The hypothesis that homology require-ments for the early steps of HR may differ from those identified in other HR assays was tested. Plasmids bearing varying amounts of homology to the chromosomal immunoglobulin μ target locus gene were constructed and tested in the 3’ extension assay. The homology require-ments for the 3’ extension assay were somewhat lower than might be expected based on other HR assays. An approximately linear relationship between homology length and 3’ extension was also established on each side of the double-strand break. The effect of excess Rad51, an essential protein involved in early HR, was also measured with respect to homology, leading to the dis-covery that increased Rad51 resulted in an increase in 3’ extension events independent of ho-mology. In summary, 3’ extension generates a potentially unstable, short-lived HR intermediate that has less dependence on homology than a completed HR product. Homology plays a role in the initiation of HR, but it may be more important in the stabilization of the intermediate than the actual generation of the early HR product detected in the 3’ extension assay. / CIHR

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Thesis (Ph.D.) -- University of Adelaide, Dept. of Genetics, 2000? / Bibliography: p. 75-84.