Browsing by Author "Gary A. Mirka, Committee Member"

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Auditory Cueing Effects on Human Performance with an Adaptive System
(2002-05-17) Warren, Heather Lynn; Gary A. Mirka, Committee Member; Michael S. Wogalter, Committee Member; David B. Kaber, Committee Chair
Adaptive automation (AA) is the dynamic allocation of complex system functions to a human operator and/or automated controller on the basis of the state of the human-task-environment and having the objective of optimizing overall system performance. Adaptive automation has been successfully applied to different types of simulated tasks in laboratory settings; however, there have been few field applications and problems remain in providing human operators of adaptive systems with adequate feedback on changing system states and modes of operation. This may result in poor operator situation awareness (SA). Previous AA research on system feedback mechanisms has primarily focused on visual cues of system state changes. Some work has investigated complex auditory icons, but no research has considered the use of verbal cues on adaptive system state changes. The current research investigated the potential for multimodal interfaces to improve adaptively automated system performance by considering multiple resource theory (MRT) of attention in system interface design. Subjects were provided with feedback on AA states via their visual and auditory senses in order to improve overall system performance and human-automation interaction. An experiment was conducted to compare the use of visual (icons), auditory (earcons) and verbal cues for conveying the state of an adaptive teleoperator (remote-control robot) in a high-fidelity, virtual reality simulation of an underwater mine disposal task. Earcons have been found to be beneficial for cueing operators of automated system states, but there has been no research to investigate earcons as feedback mechanisms in either complex human-machine interaction or in adaptively automated systems. In this study, modal cues were associated with task phase changes and teleoperator control mode changes. The type of cue and level of cue complexity (level of detail) was varied between and within subjects, respectively. Operator performance was evaluated in terms of system-state awareness, accurate control commands, and time-to-task completion. The research sought to discover which cue type was most effective for facilitating overall system performance and maintaining operator SA. Results demonstrated the manner in which humans use visual and auditory sensory cues for feedback when dealing with adaptively automated systems is in agreement with MRT. Verbal cues were identified as being superior for warning operators of system-state changes, maintaining SA (attentional resources) and facilitating overall complex system performance. The results of this study are applicable to the design of future automated systems and may serve to improve efficiency and effectiveness of performance.
Investigation of Factors Associated with Prevalence and Severity of Musculoskeletal Symptoms Among the Workers in Clinical Specialties of Radiologic Technology: An Ergonomic and Epidemiological Approach
(2004-07-20) Lamar, Sabrina Lyons; Carolyn M. Sommerich, Committee Chair; Gary A. Mirka, Committee Member; Hester J. Lipscomb, Committee Member
Little research has been done to investigate the combination of biomechanical and work organization factors associated with musculoskeletal symptoms among radiologic technologists. This cross-sectional study used a written self-report questionnaire to evaluate levels of job-related psychological stress, exposure to ergonomic stressors, and 12-month and 7-day prevalence of musculoskeletal complaints in radiologic technologists who worked in hospital or clinic-based settings in one health system. Written surveys based on interviews and direct observations of radiologic technologists and adapted from the Job Content Questionnaire and the Nordic Questionnaire were used to elicit information about psychological stress from a control-demands theory approach, work organization factors, categories of work performed, types of equipment utilized, prevalence and severity of musculoskeletal symptoms, and specific personal and health factors. Associations between personal factors, the type of work performed and the presence and severity of musculoskeletal symptoms were explored through statistical analysis. Work stress factors for radiologic technologists sin this study were compared to similar health technologists and nurses from a previously established database of Job Content Questionnaire scores. RESULTS: Radiologic technologists have a high prevalence of low back symptoms that are likely to interfere with work and leisure activities. Patient positioning was associated with an increased prevalence of low back symptoms. Transporting equipment was associated with an increased risk of experiencing right hand/wrist symptoms and dominant hand/wrist symptoms. Working as a sonographer was associated with increased risk of experiencing symptoms in the right shoulder, dominant shoulder, right hand/wrist and dominant hand/wrist. Positioning patients was associated with greater risk of experiencing musculoskeletal symptoms in the low back. Technologists in this study were older and had more education than other health care technologists from previous research using the Job Content Questionnaire. They had better scores for decision authority, decision latitude and supervisor support than the other technologists. However, they also had higher levels of physical exertion and psychological demands than the other technologists. They had a similar distribution of males versus females, and scores for created skills, job insecurity, total social support, co-worker support and job dissatisfaction as the other health technologists. Technologists in this study were older than nurses in previous research conducted with the Job Content Questionnaire. They had higher scores for decision authority and reported higher levels for psychological demands than the nurses in previous research. CONCLUSIONS: This group of radiologic technologists had a very high prevalence of musculoskeletal symptoms that were likely to interfere with work and leisure activities. Tasks related to patient handling and positioning and transporting equipment were associated with higher prevalence of symptoms. Results of this study may provide direction for future research efforts toward quantifying biomechanical exposures for radiologic technologists.
Quantification of Chondrocyte Death and Proteoglycan Content in Mechanically Impacted Articular Cartilage
(2004-06-17) Lossing, Jennifer Aimee; Peter L. Mente, Committee Chair; Simon C. Roe, Committee Member; Gary A. Mirka, Committee Member; C. Frank Abrams, Jr., Committee Member
Impact injuries can lead to cellular and matrix changes in articular cartilage, similar to those occurring in the pathenogenesis of secondary osteoarthritis. The purpose of this study was to examine the changes in cartilage following an impact injury as a model for early osteoarthritic degradation. Using an in vitro organ culture model, the proteoglycan content and the viability of chondrocytes relative to the magnitude of an impact injury, the time following the injury and the relative location within the cartilage layer was examined. In this study, it was hypothesized that injurious mechanical loading would result in increased chondrocyte death and decreased proteoglycan content with increasing load and time in culture. Paired porcine knee joints were obtained fresh and patellae were removed using sterile techniques. A total of 36 patellae were used. Twelve patellar cartilage specimens were subjected to controlled mechanical injuries to a force level of 1000 N (medium) and 12 specimens at a force level of 2000 N (high). Twelve patellae were used as non-injured controls. Following impaction, the intact patellae were placed in organ culture for 0, 3, 7 or 14 days and subsequent degenerative changes over time were assessed. Cell viability was quantified using a MTT (3,(4,5-dimethylthiazoyl-2-yl) 2,5(diphenyl-tetrazolium bromide) assay and the percentage of dead cells at various positions was determined. Proteoglycan concentration was measured using Safranin-O staining intensities. There was a significant, location dependent, cell death increase with increasing impact load. A significant location dependent decrease in proteoglycan content was observed from medium impactions, while an increase in proteoglycan content was seen from high impactions. In conclusion, the magnitude of an impact load can significantly affect the degree of matrix changes throughout the depth of articular cartilage tissue over time.