Perceptional threshold and equal sensation characteristics for random vibrations of1 or 1/3-octave band were determined on the whole body in the vertical and the hori-zontal directions and on the hand in the vertical direction in the frequency range 2-250 Hz. Difference of sensation between the vertical and the horizontal whole bodyrandom vibrations with 1-octave band was examined and it was found out that the sen-sation of the vertical vibration was equalized to that of the horizontal vibration withthe level of 10 dB larger than that of the vertical vibration above 16 Hz. Then, the vibration greatness value of the random vibration having continuous widefrequency spectrum was measured by subjective experiment and compared with thevalue estimated from each VG value of its frequency component resulting fromanalysis by an 1 or 1/3 octave band filter as, VGT=VGM, 1+0.3 ((ΣiVGi, 1)-VGM, 1) (1) VGT=VGM, 1/3+O.13((ΣiVGi, 1/3)-VGM, 1/3) (2) where VGT is the vibration greatness value (in VG) of the random vibration, VGM isthe largest VG value in all of the VGi values, and ΣVGi is the sum of the VG, values of all bands. The suffix of 1 or 1/3 indicates the data analyzed by the 1 or 1/3octave band filter. The estimated VGT values of the random vibrations are in goodagreement with the observed ones in both filter bands.
The sinusoidal vibration sensation at lying on the back was equalized into that at sitting by 10 male subjects in the frequency range between O.5 and 300 Hz, in order to obtain equal sensation contours at lying posture. This experiment was carried out for the vertical and the horizontal vibrations. As a result, the vertical vibration sensation of the lying subject receiving from 40 to 150 Hz was severer by about 12 dB in max. than that at sitting, because of the resonance of the skull. On the remainder frequency range, vibration perception was almost the same at both postures. On the other hand, the horizontal vibration sensa-tion at both postures was nearly the same in all frequency range (0.5-300 Hz). From these results, the equal sensation contours at lying posture for both directional vibra-tions were determined. The estimated equal sensation curves from above results agree with those obtained by direct measurement in which the vibration at a certain frequency from O.5 to 300 Hz was equalized into the standard vibration at 20 Hz. Thus, the assessment method of the vibration at the sitting posture established previously can be applied to that at the lying provided that the equal sensation contour for the vertical vibration is revised near 80 Hz.
The effect of repeated vigilance tasks on respiratory rate, heart rate, galvanic skin reflex (GSR), signal detection and subjective feelings were studied in three sub-jects. The subjects performed a simple task employing a rate of 35 signals/hr during 2-hr once a day and repeated it throughout a 9-day period. The mean values of respiratory rate and heart rate during the 2-hr period of the task maintained the same level throughout the 9-day period. However, the mean value of GSR frequency showed a higher value on the third day as compared with on the other days and signal detection accompanied by GSR during the 2-hr period of the task indicated a higher value on the second or third day. On and after the fourth day these values tended to decrease with fluctuations. The mean values of signal detection during the 2-hr period of the task tended to show approximately the same level throughout the 9-day period except for the decre-ment of that on the fifth day in one subject and on the seventh day in another sub-ject. Subjective intention to perform the task had a tendency to decline toward a lower level in the period of 5-8 days. On the relation between these parameters and signal detection obtained from the three subjects, it was found that variances of heart rate, GSR frequency and signal detection accompanied by GSR during the 2-hr period of the task correlated with the mean values of signal detection during the same period of the task. Correlation coef-ficients between GSR frequency and time course, and between signal detection accompa-nied by GSR and time course during the task correlated with the mean values of signal detection. On the correlations for each subject, in one of the three subjects variances of heart rate and correlation coefficients between signal detection accompanied by GSR and time course correlated with signal detection, and in another subject there was a correlation between variances of GSR frequency and signal detection.
A new method of provocation test of white finger attacks in chain saw operators was designed. It consists of i) bath of body in 24°C water for 10 min, usually in a bathtub and ii) immersion of hands in 4°C water for 1 min. Fifteen chain saw opera-tors were examined by this method and a good result was obtained. The inconsisten-cies between the complaints of the subjects and the results of provoca ion test suggest the importance of periodical examination of all chain saw operators with provocation test.
Interaction of Na+, Li+, Ca2+, Mn2+, Cd2+, Hg2+, Fe3+ and IN3+ with a phospholipid monolayer was studied in various ion concentrations. The interaction of the mono or divalent metal ions was accompanied by an increase in the surface pressure of the monolayer, on the contrary, that of the trivalent metal ions was accompanied by a decrease in the surface pressure. Saturation phenomena in the changes of the surface pressure were observed at the concentrations characteristic of the sort of metal ions. C1/2 value, which was a metal ion concentration giving half of the maximun pres-sure change, was independent of the monolayer area, and C1/2 values of these metal ions were in the order of Na+, Li+ > Ca2+ > Mn2+ > Fe3+ > Cd2+ > Hg2+ > In3+. A linear relation was found between logarithms of C1/2 values and logarithms of the acute lethal doses of the metal chlorides to rabbit or rat. From the present results, one of mechanisms of the acute metal poisoning was interpreted in terms of interaction of the metal ions with biomembranes.
Retention rate of cadmium was estimated with mice when administered a single oral dose of 115mCdCl2, and dietary factors influencing upon it were examined. High protein diet lowered the retention rate, while calcium and/or phosphorus contents of diet had no effect after 24 hours' feeding of experimental diet. After 10 days' feeding of experi-mental diet, calcium contents gave no statistically significant difference in the reten-tion rate in carcass of orally administered cadmium, but a larger amount of cadmium was retained in the digestive canals and their contents in mice kept on low calcium diet than on high calcium one at 24 and 72 hours after cadmium administration.