The purpose of this experiment was to investigate the feasibility of using psychophysical methods to determine maximum acceptable forces for various types and frequencies of repetitive wrist motion. Four adjustable work stations were built to simulate repetitive wrist flexion with a power grip, wrist flexion with a pinch grip, and wrist extension with a power grip. The study consisted of two separate experiments. Subjects worked for two days per week during the first experiment, and five days per week during the second experiment. Fifteen women completed the first experiment, working seven hours each day, two days per week, for 20 days. Repetition rates of 2, 5, 10, 15 and 20 motions per minute were used with each flexion and extension task. Maximum acceptable torques were determined for the various motions, grips, and repetition rates without dramatic changes in wrist strength, tactile sensitivity, or number of symptoms. Fourteen different women completed the second experiment, performing a wrist flexion motion (power grip) fifteen times per minute, seven hours per day, five days per week, for 23 days. There were no significant differences in maximum acceptable torque from day to day. However, the average maximum acceptable torque for a five days per week exposure was 36.3% lower than for the same task performed two days per week. Assuming that maximum acceptable torques decrease 36.3% for other repetition rates and motions, tables of maximum acceptable force were developed for female wrist flexion (power grip), female wrist flexion (pinch grip), and female wrist extension (power grip).

The physiological glare thresholds (defined as the logarithm of the ratio at threshold between illuminances of glare source and target background) of 148 subjects from 5 to 91 years of age were measured in a Wolf glare tester. The data can be represented by a power function: (physiological glare threshold) = -3 x 10-5 (age)2,4 + 2.4. When tested in a realistic driving simulator, the headlight glare resistance (defined as the logarithm of the ratio of mean "acceptable" glare illuminance to fixed ambient illuminance) of 30 of these subjects was also found to decline with age. These results are discussed in terms of a hypothesis: (headlight glare resistance) = (physiological glare threshold) + (subjective glare tolerance). All these functions have large interpersonal variation. Field measurements are provided on relevant glare ratios in typical night driving situations.

No abstract

The physiological glare thresholds (defined as the logarithm of the ratio at threshold between illuminances of glare source and target background) of 148 subjects from 5 to 91 years of age were measured in a Wolf glare tester. The data can be represented by a power function: (physiological glare threshold) =—3 × 10−5(age)2.4 + 2.4. When tested in a realistic driving simulator, the headlight glare resistances (defined as the logarithm of the ratio of mean “acceptable” glare illuminance to fixed ambient illuminance) of 30 of these subjects were also found to decline with age. These results are discussed in in terms of a hypothesis: (headlight glare resistance) = (physiological glare threshold) + (subjective glare tolerance). All these functions have large interpersonal variation. Field measurements are provided on relevant glare ratios in typical night driving situations.

The purpose of this experiment was to quantify maximum acceptable forces for ulnar deviation motions of the wrist at various repetition rates. Subjects grasped a handle with a power grip and moved it through a 1.40 rad (80 degrees) ulnar deviation wrist motion (similar to a knife cutting task). A psychophysical methodology was used in which the subject adjusted the resistance on the handle and the experiment manipulated or controlled all other variables. Two series of experiments were conducted. Thirteen subjects completed the first series, which investigated repetition rates of 15 and 20 motions per minute. Eleven subjects completed the second series, which investigated 15, 20, and 25 motions per minute. Subjects performed for 7 hours per day, 5 days per week, for 4 weeks in the first series and 5 weeks in the second series. The subjects were instructed to work as if they were on an incentive basis, getting paid for the amount of work they performed. Symptoms were recorded by the subjects during the last 5 minutes of each hour. The results are presented and compared with maximum acceptable forces for wrist flexion and extension.

No abstract

No abstract

No abstract