Piloting a commercial aircraft involves performing multiple tasks in a real-time environment that require pilot's attention and cognitive resource allocation. Due to resource limitation, pilots must perform cockpit task management (CTM) because they cannot perform all tasks that demand their attention at once. Hence, pilots must prioritize the tasks in the order of most to least important and allocate their resources according to this prioritization. Over the years, pilots have developed rules of thumb for task prioritization in facilitating CTM. A task prioritization error is simply an error made by the flight crew when they perform lower priority tasks as opposed to higher priority tasks, where priority is determined by the Aviate-Navigate-Communicate-Manage Systems (A-N-C-S) task ordering. Although the level of flight deck automation has been suggested as one factor influencing the likelihood of task prioritization errors, there has so far been just one study directed towards confirming that hypothesis. Hence the first objective of this study was to determine the effect of the level of automation on CTM performance. CTM performance was measured by looking at the number of task prioritization errors committed by pilots in different levels of automation. In addition to the level of automation, there was also reason to believe that the pilot's automation proficiency might affect CTM performance. Therefore, the second objective of this study was to determine the effect of automation proficiency on CTM performance. Nine airline transport pilots served as subjects in this study. Three flying scenarios and three levels of flight deck automation were simulated on a part-task flight simulator. Each pilot ran three different combinations of flight deck automation and flying scenario. The CTM performance for each pilot was determined by identifying the number of task prioritization errors committed in each experiment run. The average number of errors in different levels of automation and automation proficiency were compared for their effect on CTM performance using Analysis of Variance (ANOVA). It was found that the level of automation affected CTM performance depending scenarios in which phases of flight differed. However, automation proficiency, measured by glass cockpit hours, was found to have no effect on CTM performance. / Graduation date: 2000

Graduation date: 1995

Graduation date: 1993

The computation of texture and of stereoscopic depth is limited by a number of factors in the design of the optical front-end and subsequent processing stages in humans and machines. A number of limiting factors in the human visual system, such as resolution of the optics and opto-electronic interface, contrast, luminance, temporal resolution and eccentricity are reviewed and evaluated concerning their relevance for the recognition of texture and stereoscopic depth. The algorithms used by the human brain to discriminate between textures and to compute stereoscopic depth are very fast and efficient. Their study might be beneficial for the development of better algorithms in machine vision.

Thesis (Ph. D.)--Ohio State University, 2006. / Full text release at OhioLINK's ETD Center delayed at author's request

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 110-121).

TB recurrence is defined as a new episode of bacteriologically positive TB in a patient previously declared successfully completed treatment. Our study objective was to identify risk factors of recurrence among HIV-infected and HIV-uninfected TB patients. Based on a population-based TB/HIV surveillance database of Chiang Rai Province, Thailand, a retrospective cohort of TB patients with successful completions of treatment between 1997 and 2008 was constructed. Poisson regression was used to model independent effects of risk factors. TB recurrence rates were 5.4/1,000 PYs and 9.7/1,000 PYs for HIV-uninfected and infected TB patients, respectively. We identified that among HIV-uninfected patients, older age, being hilltribe, being prisoners, were at higher risk of recurrence. While among HIV-infected patients, younger age, being male, and having been cured from initial episode were associated with higher recurrence rates. Targeted, practical preventive and treatment strategies for those patients need to be implemented to lower the TB recurrence rates. / Epidemiology

Thesis (Ph. D.)--University of Chicago, Dept. of Pathology, August 1999. / Includes bibliographical references. Also availabel on the Internet.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 56-62). Also available on the World Wide Web.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 109-124).