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Biomedical subjects

A Gilchrist

Publications and source records attributed to A Gilchrist.

43 records · Page 3Linked to original sources
PubMed1984

Perception of lightness and illumination in a world of one reflectance.

Observers looked into a miniature room in which everything was painted matte white, or--in another room--matte black. They made both reflectance and illumination judgments for eight test spots. The test spots (which varied in luminance) were perceived as approximately equal in reflectance--not different, as conventional contrast theories would seem to require. The illumination matches made to the same points, however, closely paralleled the pattern of actual illumination levels, and this result is discussed as evidence that edges are classified as changes in either reflectance or illumination. The white room was correctly perceived as white, and the black room was perceived as middle gray; similar results were obtained even when the luminances in the black room were higher (owing to higher illumination) than the corresponding luminances in the white room. An explanation in terms of differences in gradient patterns is presented and supported with luminance profiles.

Discrimination, Psychological↗
PubMed1968

Skier's fracture.

Explore the source record for details and available documents.

Fractures, Bone↗
PubMedDate not supplied

The effectiveness of foams in bicycle and motorcycle helmets.

The optimisation of the foam used for shock absorption in bicycle and motorcycle helmets is considered. It is shown that for the former, the ideal foam yield stress for impact with a rigid protruding object is higher than that for impact with a deformable flat object. Therefore, the design must be a compromise. For motorcycle helmets the shell stiffness is higher and the force to cause shell buckling plays a significant part in the response. Lower density foams can be used only if the impact test standards are rewritten with less emphasis on impacts with convex and pointed objects.

Bicycling↗