Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 143-162).

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 158-165).

Thesis (Ph. D.)--University of California, San Diego, 2003. / Vita. Includes bibliographical references (leaves 102-105).

Includes bibliographical references (p. 55-57).

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references. Also available in print.

Heart rate monitoring (HRM) is an essential tool for monitoring physical activity and as a diagnostic tool in the clinical setting. The ability to monitor heart rate gives users and clinicians vital information about the current condition of the cardiovascular system before, during, and after exercise. However, HRM requires a telemetric chest strap, and comfort, transmission and fit can become problems with the chest strap. New technology using photoplethysmography (PPG) has emerged recently to provide the possibility of HRM without a telemetric chest strap during exercise. The aim of this study was to determine if a new device could detect heart rate over a broad range of skin types (I-V), and whether what wavelength would be most suitable for detecting the signals. A light emitting diode (LED) based PPG system was used to determine heart rate by change in pulsatile blood flow on 22 apparently healthy individuals (11 male and 11 female, 20-59 years old) of varying skin type. Skin type was classified according to a questionnaire in combination with digital photographs with a skin type chart. Each subject was exposed to four different wavelengths (470 nm, 520 nm, 630 nm, and 880 nm) and multiple trials were conducted on each wavelength. Heart rate detection was represented by modulation of the incident light wave and normalized by saturation into a pulsatile waveform represented as modulation average. The 520nm wavelength classified as visible green light provided a significantly greater (p<0.001) ability to detect heart rate. Increasing levels of melanin, or darker skin type (Type V) showed decreased modulation however this trend was not significant (p<0.067). There was no significant interaction between the wavelength of light and the skin type. In conclusion, a PPG based device can detect heart rate across skin types and use of a green light wavelength provides an even greater resolution. / text

My background in music and visual art has led to an exploration of combined disciplines. Throughout the past three years of graduate study at The University of Texas at Austin, my research has focused on the visual representation of music using light and sound. This area of study has touched upon a wide range of historical developments, from ancient Greek philosophy to contemporary experimental film. Through my research, I have examined the ways in which music-visualization has been influenced by shifting social and philosophical views. In turn, my own artistic practice has come to include the production of music-visualization devices. I'm interested in both the history of the light show as a cultural phenomenon, and in the development of new approaches to musical performance incorporating the union of light and sound. The following report discusses two major projects that I have worked on at UT, reflecting on the influences behind them, and their potential for growth beyond graduate school. / text

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

published_or_final_version / Public Health / Master / Master of Public Health