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Biomedical subjects

W P Nash

Publications and source records attributed to W P Nash.

2 recordsLinked to original sources

Information gating: an evolutionary model of personality function and dysfunction.

Utilizing principles of evolutionary biology, a model is developed which defines the essential adaptive functions of personality as a whole, and describes how failure in those functions produces the maladaptations characteristic of personality disorders. In this model, personality is hypothesized to have evolved specifically to make human culture possible by managing the flow of information within the culture, especially by mediating teaching and learning, competition and cooperation, and leading and following. These essential culture-forming capacities of personality have at their root the more basic function of information gating, which is defined here as the continuous regulation by personality of its openness for the bidirectional flow of sensory, cognitive, emotional, and motor information between internal self and external social systems, to best meet the needs of both in various situations. The maladaptations characteristic of personality disorders are postulated to be due to their being chronically and frequently too open or too closed for expressing or assimilating social information, given their circumstances. The relationship of this model to other evolutionary models of personality is discussed, as are its clinical and research implications.

Adaptation, Psychological↗

Electron probe micro-analysis for subsurface demineralization and remineralization of dental enamel.

A quantitative study of fluoride distribution profile changes in dental enamel was conducted by means of electron probe micro-analysis (EPMA). Fluoride-deposited hydroxyapatite powders were chosen as fluoride standards, and analytical conditions were optimized. The lower limit of detection for fluoride was estimated to be 270 ppm, with an accelerating voltage of 5 kV, a specimen current of 40 nA, and a counting time of 40 seconds. Fluoride profiles in fluoride-treated dental enamel, which exhibited intact surface layers and subsurface demineralization, were determined. The results were also compared with those of an acid-abrasion method, and reasonable consistency was found between these two methods, although the acid-abrasion procedure yielded a slightly lower fluoride content in the initial layers, followed by a higher content of fluoride in the deeper layers. The precision of fluoride profile data obtained from EPMA permits further studies to be conducted on the kinetics of subsurface demineralization and intact surface layer formation ("white spot" formation) which is observed during the acid challenge of dental enamel.

Animals↗