Thesis (M.S. in App. Math.)--School of Mathematics, Georgia Institute of Technology, 2004. Directed by Matthew Realff. / Includes bibliographical references (leaf 99).

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Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Each year the rate of slip and fall accidents increases among older individuals. Most falls among the elderly occur indoors rather than outdoors, and of the falls that occur in the residential home, over 600,000 are due to floor covering materials. In particular, carpet and vinyl are common floor coverings used in the home today as the elderly often transition from carpet to vinyl and vice versa. When transitioning between two different floor surfaces, older adults may adjust their gait to avoid a slip, trip, or fall. Many studies have assessed gait parameters of elderly individuals on either carpet or vinyl. Yet, few have studied the effect of transitioning between two different floor surfaces on the gait of older individuals. This study investigated the effect of transitioning between different floor coverings on the gait characteristics of the elderly. For this study, 14 elderly (65 years old and over) and 14 young (18 to 35 years old) individuals participated. All participants walked on different transitional floors, namely carpeted floors, vinyl floors, and floors covered with both vinyl and carpet. While the participants were walking on the walkway, different gait parameters were measured, including the required coefficient of friction, stride length, transitional acceleration of the whole body center-of-mass (COM), heel velocity at heel contact, perception of slipping/tripping, and toe clearance. It was hypothesized that older participant's gait parameters would be different from their younger counterparts. Also, the older participant's gait adaptation would increase the likelihood of a slip and trip propensity while transitioning between different floor surfaces compared to the younger participants. More specifically, for the elderly, transitioning from carpeted floor surfaces to vinyl floor surfaces would increase the slip propensity and transitioning from vinyl floor surfaces to carpeted floor surfaces would increase trip propensity, and therefore increase the likelihood of fall accidents. In the present study, it was found that elderly individuals had greater toe clearance than their younger counterparts. Also, the elderly individuals had smaller toe clearance on the carpet than on the vinyl, which would increase the probability of a trip-induced fall when walking on the carpet. Further, the propensity of a slip-induced fall accident increased on the vinyl shortly after transitioning from the carpet to the vinyl due to the slower transitional acceleration of the whole body COM and the increased friction demand, especially during the toe-off phase of the gait cycle, rather than heel contact phase of the gait cycle. In addition, it was also found that an increase in heel contact velocity and step length increases the propensity of a slip-induced fall accident. Furthermore, this propensity is greater while transitioning from a carpet to a vinyl floor surface, especially for elderly individuals. The results of the present study indicate that transitioning between different floor surfaces changes the biomechanical parameters of gait, especially for the elderly individuals. Although the increased likelihood of a slip or trip accident was found throughout the changes in biomechanical gait parameters, the elderly individuals who participated in this study did not perceive of slipping and tripping much. Therefore, elderly individuals should be made aware of / Master of Science

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Mites are endemic and allergy to mite excreta and parts is one of the most common allergies. Health care practitioners have recommended the removal of carpets from homes of people with mite allergies. Little, if any, consideration is given to the fact that some persons may benefit directly from the presence of carpet in their homes. In the allergen and mite research literature, carpets are rarely described as having unique characteristics and are generally referred to as a generic entity. Carpets, however, do have unique characteristics that define their construction, appearance, wearability, and cleanability. Seventy-two pieces of commercially available, residential flooring materials were inoculated with identical numbers of mites, Dermatophagiodes farinae, and placed in the Textiles Conditioning Lab at Virginia Tech. The mites and carpet pieces were maintained in the lab, under identical, environmentally controlled conditions for 6 weeks, then the mites were extracted and counted. On the basis of the results of statistical tests run on the study data, the null hypothesis, that there is no difference between the numbers of mites grown on the different flooring conditions, was rejected. Statistically significant differences exist between the hard floor and the nylon carpet, between hard floor and olefin carpets, but no difference between hard floor and wool carpet. Nylon was the carpet fiber that was most supportive of the growth of house dust mites, olefin was the second most supportive, and wool carpet and hard floor were similar in being the least supportive. / Master of Science

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