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Biomedical subjects

K M Hamilton

Publications and source records attributed to K M Hamilton.

5 recordsLinked to original sources
PubMed1989

Limitations of postural equilibrium tests for examining simulator sickness.

The psychometric properties of four ataxia tests and their sensitivities to disorientation were examined to assess their potential for measuring balance disturbances frequently reported with simulator sickness. The study was conducted in two parts. In the first, subjects practiced for 10 sessions to examine learning effects and to stabilize performance. In the second, the sensitivities of the four tests were examined by comparing performance before and after exposure to sensory conflict produced using a disorientation training flight simulator. Subjective measures of disorientation, including reports of postural disequilibrium, were also collected. The results indicated initial learning on all four ataxia measures. Two of the tests, the Stand on One Leg Eyes Closed and the Sharpened Romberg, exhibited acceptable levels of reliability. However, only the latter showed sufficient sensitivity to corroborate subjective reports of postural disequilibrium.

Adult↗
PubMed1985

Hydroxylapatite as an alloplastic graft in the treatment of human periodontal osseous defects.

Twelve patients, 32 to 60 years of age, received a polycrystalline ceramic form of pure dense hydroxylapatite as an alloplastic bone implant material in intrabony defects following reflection of full mucoperiosteal flaps, root planing and defect-curettement. The defects were measured from an acrylic stent, using an endodontic silver point which was placed to the base of the defect. Similarly, debrided and curetted defects in the same patients were not implanted and served as controls. Recalls for documentation and plaque control were at 1, 2, and 4 weeks, and at 3, 6 and 9 months. Measurements relating to changes in defect-depth were made upon reentry at 9 months. The twelve defects, serving as controls, showed very little difference between the pretherapy and 9-month measurements. The initial mean measurement from the base of the defect to the highest alveolar crest was 4.27 mm and the 9-month mean measurement after curettage only was 3.36 mm. In terms of resolution of the original defect this amounted to 19.49% reduction, but a 0.46-mm mean loss in height of the alveolar crest provided an actual percentage fill of the original defect of 9.91%. Of sixteen experimental defects, the same initial mean measurement from the base of the defect to the highest alveolar crest was 5.18 mm and the 9-month mean measurement after grafting was 2.43 mm. In terms of resolution of the original defect, this amounted to a 53.57% reduction, but in contradistinction to the curettage sites, a mean increase in height of the highest alveolar crest of 0.61 mm gave a true percentage fill of the original defect of 66.89%. At the 9-month reentry, the implanted mass seemed to be partially "calcified" and was resistant to penetration with a probe or removal with a curette. The data and clinical impression strongly suggest that hydroxylapatite has a potential as an alloplastic implant with clinically apparent acceptance by the soft and hard tissues.

Adult↗
PubMed1977

Memory load, critical features and retrieval processes in facial recognition.

A Sternberg-type varied set procedure was used in which the set of stimuli associated with the "different" response was, in some cases, large and unspecified. A 3-factor design was used with repeated measures on list length (1, 2, or 4 faces), decision ("same" or "different"), and number of critical features varied between memory and target faces (0, 2, 4, or 7). Reaction times of college students for recognition of faces were analyzed to determine the nature of the retrieval processes employed. Reaction times were faster as the number of feature changes increased, and both parallel and serial processes were indicated for both "same" and "different" responses.

Discrimination, Psychological↗