Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 88-98). Available also in a digital version from Dissertation Abstracts.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 15, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Ping Yu. Vita. Includes bibliographical references.

A polarization sensitive optical coherence tomography (PS-OCT) instrument is presented for the study of glaucoma. Glaucoma is the second leading cause of blindness worldwide and causes irreversible damage to the retina. This PS-OCT system was built to perform retinal imaging with a swept source laser providing a 28 kHz A-scan repetition rate. Thickness, phase retardation, birefringence and reflectance index measurements were taken from the primate eyes on a weekly or semi-weekly basis through the course of a 30 week study. Statistical analysis of these measurements indicates that the reflectance index is the earliest measured indicator of glaucomatous changes and a potential marker for early glaucoma diagnosis. / text

This thesis discusses certain aspects of the noninvasive imaging technique known as optical coherence tomography (OCT). Topics include three-dimensional image rendering as well as application of the Fast Fourier Transform to reconstruct the axial scan as a function of depth. Implementations use LabVIEW system design software and a Xilinx Spartan-6 field-programmable gate array (FPGA). The inherent parallel-processing capability of an FPGA opens the possibility of designing a "super-sensor" which entails simultaneous capturing of image and sensor data, giving medical practitioners more data for potentially improved diagnosis. FPGA-based processing would benefit many methods of characterizing biological samples; OCT and photonic crystal microarray biosensors are discussed. / text

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

Investigating the neurophysiology behind our action encoding system offers a way of probing the underlying mechanisms regarding how we understand seen action. The ability to mentally simulate action (motor simulation) is a strong proposal to understand how we interpret others’ actions. The process of how we generate accurate motor simulations is proposed to be reliant on the context of the movement and sensory feedback from the limb. However, the neurophysiological mechanisms behind motor simulation are not yet understood. Known motor physiology for right-handed individuals show there is a left parietal-frontal network for the mental simulation of skilled movements; however, it remains unclear whether this is due to right limb dominance of the observer’s motor system because action simulation research has been focused primarily on right-handed individuals. The goal of this dissertation is to understand the underlying neurophysiology of the motor simulation process during action encoding. Generally, we propose different strategies of action simulation between right and left handed individuals. More specifically, we propose that right-handed individuals rely on their motor dominant left hemisphere for action encoding and motor simulation, while left-handed individuals will rely on their motor dominant right hemisphere. We will test this by evaluating neurobehavioral patterns of potential symmetry and asymmetry of motor simulation and action encoding based on patterns of limb dominance. We will also evaluate how impaired sensory feedback affects motor simulations, which can reveal how limb state affects the simulation process. The results of this series of studies will fill a void in our basic understanding of the motor simulation process and may generalize to populations with upper limb functional loss. Specifically, those with different hand dominance may require different rehabilitation programs in order to retrain an affected limb.

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