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971.
Serial manipulators are often used in biomechanical testing of human joints because they are precise, repeatable instruments that can create interesting loading scenarios. Unfortunately, commercial serial manipulators often do not have acceptable global positional accuracy due to manufacturing tolerances, assembly errors, and other mechanical imperfections. Numerous calibration methods have been reported which calibrate geometric and non-geometric parameters to reduce static position errors under constant loading conditions. However, the manipulator's global accuracy during continuous motion with time-varying external loading conditions is often not addressed but is necessary for joint biomechanical testing. Using the Mitsubishi PA10-6CE as a case study, a novel functional calibration procedure was developed that performs both static and dynamic calibration. The calibration uses optimization techniques to populate a 34-parameter model that accounts for the robot's geometric and non-geometric parameters and significantly reduces the mean/peak static and dynamic position errors to 0.368/0.67 mm and 0.353/0.81 mm, respectively, while externally loaded. 相似文献
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Seventeen women (mean age 31 yr) participated in a training program divided into an initial 9-wk period and a subsequent 52-wk period, during which time 6 continued to exercise and the remainder detrained. Improvements in VO2max were significant (+34%) during the initial 9 wk and small (+5%) for the final 52 wk. Four women who stopped training showed a decrease in VO2max (-10%) during the last phase. During the initial 9 wk, central adaptation was important, with SV showing an increase of 28% at 80% VO2max. Peripheral adaptation (a-v O2 difference) was unchanged. Subjects who trained an additional 52 wk showed a slight drop in SV at submaximal work loads from the initial increase following the first 9 wk. When compared with the initial test the change at 9 wk in peripheral adaptation was a small and nonsignificant rise, followed by a significant increase at 61 wk. Women who are very unfit initially (predicted VO2max of 28 ml/kg-min), apparently adapt to the initial training with a central change followed by a much stronger peripheral adaptation during a longer training program. 相似文献
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A method is described for providing reproducible S phase parasynchrony in both normal mesenchyme and transformed epithelia. Cells were seeded at low density in medium containing 10% serum. 24 h later the serum concentration was reduced to 0.5%. After 110th the cells were collected at the G1/S boundary in fresh medium containing 10% serum plus 2.5mM hydroxyurea over 20h. After removal of hydroxyurea and trypsinization the re-plated cells entered the S phase with a high degree of synchrony, as judged by autoradiography, pulse-labelling with 3H-thymidine, cell growth and time lapse cinematography. By 6h after synchronization 80% of the population had entered the S phase and between 10-13h 70% went through mitosis. 相似文献
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Juvenile Tilapia mossambica (Peters) are extremely tolerant of depth and can compensate to a depth increase of 0 to 33 m in a few minutes. As the fish grow they become less able to compensate to deep water. At a total length of 15–18.5 cm small adult male T. mossambica can compensate to 20 m whereas females can only compensate to 13 m. Large adults (20–25 cm) of both sexes compensated to 11.5 m (range 9.5–13 m). Adult fish require 4 to 7 days for maximum depth compensation at 22°C. Analysis of the oxygen content of the swimbladder indicated that this gas accounts for over half the gas in surface equilibrated fish. Oxygen secretion into the swimbladder appears to be the mechanism of equilibration at depth. 相似文献
980.
Length dependence of rate constants for end-to-end association and dissociation of equilibrium linear aggregates 总被引:3,自引:0,他引:3 下载免费PDF全文
T L Hill 《Biophysical journal》1983,44(2):285-288
A semi-quantitative analysis is given of the length dependence of the rate constant for association (annealing) of two long linear aggregates in solution. The equilibrium constant for this process, or its inverse (fragmentation or dissociation), is relatively easy to formulate from appropriate partition functions. From these two ingredients, the length dependence of the rate constant for spontaneous fragmentation can be deduced. Numerical examples are included. 相似文献