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Thesis (D.M.A.)--University of California, San Diego, 2007. / Title from 1st page of PDF file (viewed Mar. 5, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references: P. 50-55.

Thesis (Ph. D.)--Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Henderson, Clifford; Committee Member: Hess, Dennis; Committee Member: King, William; Committee Member: Lu, Hang; Committee Member: Tolbert, Laren.

Thesis (M.S.)--Ohio University, August, 1998. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, March, 1997. / Title from PDF t.p.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 47-49). Also available on the World Wide Web.

Thesis (M.S.)--Mechanical Engineering, Georgia Institute of Technology, 2005. / Jiri Janata, Committee Member ; Shreyes Melkote, Committee Member ; Steven Danyluk, Committee Chair. Includes bibliographical references.

This thesis describes the design and testing of a floppy disk drive based digital recorder. The device was originally built for a geomagnetic research project, but is also suitable for other phenomena with time scales from fractions of a second to approximately one day. The system is designed specifically to improve the reliability for long-term observing programs and to enhance the efficency of the subsequent data analysis procedures. Using an STD-Z80 BUS microcomputer, under the control of a Forth language program, the recorder stores digital data on removable 8-inch floppy disks. This thesis explicitly addresses the issue of cost and provides the necessary detail for reproduction of the device. A procedure is described for preparing the acquired data for analysis using computing facilities equiped with an appropriate disk reader. Also presented is a quantitative and qualitative evaluation of the recorder's performance when applied to both synthetic and natural signals. The latter include geomagnetically induced currents in power transmission lines. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The properties of muonium(μ⁺e⁻) and positronium(e⁺e⁻) are altered significantly in the presence of matter. The study of these exotic H-like atoms provides a unique perspective on atomic interactions with atoms, surfaces, and solids. This theme is explored in a variety of hosts. The cross section for spin 1 positronium to be converted to spin 0 positronium during collisions with O₂ molecules has been measured from 120 °K to 630 °K in an SiO₂ powder moderator using a positron lifetime technique. The results indicate that positronium does not thermalize in the powder below 450 °K. The spin conversion cross section increases slightly with temperature above 450 °K. A theory for spin conversion of positronium by a spin 1 molecule is developed and used to interpret the data. Muon Spin Rotation measurements, in SiO₂, Al₂O₃, and MgO powders at low temperature in an atmosphere of He indicate that muonium emerges from the surfaces regardless of the ambient temperature of the powder. The muonium spin relaxation rate in Al203 in a He(or Ne) atmosphere is found to be a linear function of the fraction of surface area not covered by adsorbed He(or Ne). The cross sections for muonium to scatter elastically off adsorbed He and Ne atoms have been measured to be 11.0±0.2 Ų and 8.9±0.2 Ų, respectively. The first observations of muonium in the condensed phases of Ar, Kr, and Xe are presented. The data indicate that there is a high probability of muonium formation in all cases. The spin relaxation rate of muonium in solid Xe is ten times that in the liquid, where the random local fields from the nuclear moments of ¹³⁹Xe and ¹⁴¹e are averaged by additional translational motion. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Conventional imaging techniques for cancer detection have difficulty finding small, deep tumors. Single-detector radiation probes have been developed to search for deep lesions in a patient who has been given a tumor-seeking radiopharmaceutical. These probes perform poorly, however, when the background activity in the patient varies greatly from site to site. We have developed a surgical dual-detector probe that solves the problem of background activity variation, by simultaneously monitoring counts from a region of interest and counts from adjacent normal tissue. A comparison of counts from the detectors can reveal the class of tissue, tumor or normal, in the region of interest. In this dissertation we apply methods from statistical decision theory and derive a suitable comparison of counts to help us decide whether a tumor is present in the region of interest. We use the Hotelling trace criterion with a few assumptions to find a linear discriminant function, which can be reduced to a normalized subtraction of the counts for large background count-rate variations. If area under the ROC curve is our figure of merit, the likelihood ratio is the optimum discriminant. We model likelihood functions of the data given the "tumor" and "no-tumor" hypotheses, and calculate the likelihood ratio. Using a spatial response map of the dual probe, a computer torso phantom, and estimates of activity distribution, we simulate a surgical staging procedure to test the dual probe and the discriminant functions. Results of the simulations show that the dual probe effectively solves the problem of background activity variations when used with any of the discriminant functions derived in this dissertation.