Dissertation (Ph.D.)--Auburn University, 2009. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph. D.)--University of Chicago, Department of Physics, 2001. / Includes bibliographical references. Also available on the Internet.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 67-69). Also available in electronic version. Access restricted to campus users.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.

Since their experimental discovery in 2008, topological insulators have been catapulted to the forefront of condensed matter physics research owing to their potential to realize both exciting new technologies as well as novel electronic phases that are inaccessible in any other material class. Their exotic properties arise from a rare quantum organization of its electrons called ``topological order,'' which evades the conventional broken symmetry based-classification scheme used to categorize nearly every other state of ordered matter. Instead, topologically ordered phases are classified by topological invariants, which characterize the phase of an electron's wavefunction as it moves through momentum space. When a topologically ordered phase is interfaced with an ordinary phase, such as the vacuum, a novel metallic state appears at their shared boundary. In topological insulators, this results in the formation of a two-dimensional metallic state that spans all of its surfaces. The surface state electronic spectrum is characterized by a single linearly dispersing and helically spin-polarized Dirac cone that is robust against disorder. The helical nature of the surface Dirac cone is highly novel because the Dirac electrons carry a net magnetic moment and are capable of transporting 100% spin-polarized electrical currents, which are the long-sought electronic properties needed for many spin-based electronic applications. However, owing to the small bulk band gap and intrinsic electronic doping inherent to these materials, isolating the surface electronic response from the bulk has proven to be a major experimental obstacle. In this thesis, we demonstrate the means by which light can be used to isolate and study the surface electronic response of topological insulators using optoelectronic and nonlinear optical techniques. In chapter 1, we overview the physics of topological order and topological insulators. In chapter 2, we show how polarized light can be used to generate and control surface electrical currents that originate from the helical Dirac cone. In chapter 3, we demonstrate that the nonlinear second harmonic generation of light from a topological insulator is a sensitive surface probe and can be used to detect the breaking of space-time symmetries and monitor changes in the surface carrier density. / Physics

No description available.

Transgenic mosquitoes are beneficial for the design and implementation of various pathogen control programs. However, low and variable expression of transgenes caused by position effects is a hindrance to the characterization and effective use of transgenes in mosquito species. The use of insulator sequences to flank transgenes may have the ability to overcome position effects caused by the genomic environment surrounding the insertion site. CTCF is a multifunctional protein, conserved from humans to Drosophila. Its role as an enhancer blocker in the Drosophila bithorax complex and its proximal binding to other insulator proteins on Drosophila chromosomes makes it a good candidate for identifying insulator sequences throughout the mosquito genome that may be used to improve mosquito transgenesis. Its multi-functionality as a transcription factor and genome organizer also makes CTCF worthy of investigation for an improved understanding of the regulation of the mosquito genome. This study uses chromatin immunoprecipitation with an An. gambiae CTCF antibody followed by Illumina deep sequencing (ChIP-Seq) to identify regions of CTCF binding throughout the An. gambiae genome. A subset of the CTCF binding site peaks was validated using ChIP-PCR. Another subset of this data set, including the ChIP-PCR validated peaks, was input into the motif finding tool, AlignACE, in order to identify a CTCF binding site consensus. Four motifs were identified, none of which were found in more than 11.9% of the ChIP-Seq data set. These results lead us to conclude that An. gambiae CTCF binds to a wider variety of sequences compared to Drosophila CTCF. This work also includes a comparison of the expression profiles of the dipteran insulator proteins, Su(Hw) and CP190, with that of CTCF across multiple life stages in Ae. aegypti. The results of this study suggest the possibility of genomic colocalization, as has been recently discovered in Drosophila. The identification of CTCF binding site peaks throughout the An. gambiae genome provides a large data set of potential insulator sequences that may be used to improve mosquito transgenesis, and provide a new model for the study of CTCF function in a species with medical significance.

No description available.

Thesis (M.S.)--Texas State University-San Marcos, 2007. / Vita. Appendices: leaves 69-80. Includes bibliographical references (leaves 81-83).

Thesis (Ph. D. in Physics)--Vanderbilt University, Aug. 2008. / Title from title screen. Includes bibliographical references.