Measuring lower leg swelling: optimum frequency for impedance method.

The optimum measuring frequency of the impedance plethysmograph is determined for the estimation of leg volume increase caused by a sitting work load. Ten subjects sit for 1 h without leg movement. Right calf impedance is measured by the four-electrode method. The detecting electrodes are fixed on the calf with an inter-electrode distance of 15 cm. The measuring frequencies are 5, 10, 50 and 100 kHz. As the indices of leg swelling, three values are calculated: percentage change in impedance, volume change and percentage change in volume. The mean, standard deviation and coefficient of variation (CV) are calculated from the mean values of indices for each subject and frequency. The CV of all three indices increases when measurements are taken at higher frequencies. Among the three indices across all measuring frequencies, the volume change shows the highest CV (0.42 at 5 kHz, 0.82 at 100 kHz), and the percentage change in impedance shows the lowest CV (0.32 at 5 kHz, 0.72 at 100 kHz). It is concluded that the measuring frequency of 5 to 10 kHz is the best to obtain accurate data for the evaluation of lower leg swelling.

Standing.

The paper summarizes 12 papers by the authors over the last six years on various aspects of standing. This paper is divided into four sections. The anthropometry section discusses foot dimensions (including volume and footprints) and discusses leg-length discrepancy. The criteria section discusses the usefulness, for standing, of various physiological criteria and of body comfort votes. The floor surfaces section discusses concrete, rubber mats and carpet. The posture section discusses standing postures.

Occurrence sampling in a residence hall foodservice: entrée production times.

Occurrence sampling was used in the main production area of a university residence hall foodservice to measure and analyze work functions involved in entrée production and to determine time requirements for entrée categories. Sixteen entrées were investigated: seven single-item, six combination, and three roast. Data collection took place in a period of 5 days over a 2-week span. A total of 3,891 observations was recorded during 297 labor hours. Results of the study indicated 59.2% of the total labor time was spent in direct work, 23.3% in indirect work, and 17.5% in delays. The preparation work function represented the highest proportion of labor time for both single-item and roast entrées, but prepreparation consumed the greatest amount of time for combination entrées. Mean labor minutes per serving for the 16 entrées were 0.9, with a range of 0.4 to 3.5. Mean labor minutes per serving for combination entrées were 1.4, which was the highest among the three groups; range was from 0.4 to 3.5 minutes per serving. For single item entrées, mean minutes per serving were 0.6, with a range of 0.4 to 0.8. Roast entrées, had a mean time requirement per serving of 0.5 minute, with a range of 0.4 to 0.6.

Occurrence sampling in a residence hall foodservice: cleaning times for selected vegetables.

Objectives of this study were to analyze work functions in a vegetable pre-preparation unit of a large residence hall foodservice using occurrence sampling and to determine cleaning times for selected vegetables. Data were collected in the early spring for 14 consecutive days. Total hours worked were 349.5; 2,174 observations were recorded. Percentage labor time and minutes expended were calculated for cleaning selected vegetables. Average cleaning times were established for minutes per pound and purchase unit for carrots, celery, head lettuce, leaf lettuce, yellow onions, and red and white potatoes.

Applying concepts of visual perception to formats of hospital menus.

Standardized printed menu formats for all diets utilizing concepts of visual perception were evaluated in a machine-paced hospital tray-assembly process. Formats of existing menus differed among the various diets. On the redesigned menus, all menu items were arranged in basic groups which were assigned specific positions; groups were accentuated by white strips across the various color-coded selective menus; and accessory items were placed in specific, standard positions on all menus. Criteria for evaluating the effect of using the redesigned menu in tray assembly operations were: overall productivity, individual productivity, and error rate per tray. Data were charted (a) during a control period when the existing menu formats were used to provide baseline data and (b) during an experimental period when the redesigned menu formats were used. Overall productivity was measured by man-minutes per tray. Video tapes of five station operators servicing selected trays were made to study individual productivity. Station operator and checker accuracy were measured in terms of ratio of error-free trays, errors per tray, and errors to possibility of errors per tray. Man-minutes per tray decreased significantly in the experimental period from 2.44 to 2.17--a productivity increase of 11.1 per cent. The individual productivity analysis revealed no significant changes from control to experimental periods. Accuracy of the tray assembly station operators improved significantly. Decreases in ratio of mean number of errors to possibility of errors per tray were recorded in the experimental period. The error rate per tray decreased 44.9 per cent from 0.48 to 0.26, and the ratio of errors to possibility of errors per tray decreased from 6.3 to 3.5 per cent. The percentage of error-free trays rose from 69.9 to 80.9 per cent. Checkers' errors per tray did not change significantly from control to experimental period when data for the two periods were compared. This study provides a practical means of increasing productivity and improving accuracy of the machine-paced tray assembly process.