In previous reports of this series, psychological experiments have been carried out on subjects sitting on a vibration table without cushions. In the case sitting on a cushion, vibration influence may be assessed either by measuring vibration acceleration values at the most adjacent spots on body surface touching the cushion, or by obtain- ing them by subtracting the attenuation values of the cushion from the vibration spectrum given to the subject without it. As the latter is capable of pursuit by several techniques in the laboratory test, measuring methods of the attenuation effect of the cushion are studied in this report. Three methods, threshold shift, mechanical impedance and acceleration ratio, were devised for the measurement of attenuation effect of the cushion to vertical and horizontal vibrations in frequency range between 2 and 100 Hz. Patterns of the at- tenuation effect on two resilient samples were determined for both vibrations using these methods. Measuring method of the vibration spectrum directly given to the subject sitting on the resilient material was also deduced for practical use.
Biochemical response of rabbits subjected to a sensory electrical stimulation, which gives a painful stimulus on the ear-lobe of animal with less body shake, was examined with the intention of finding out some objective indices for emotional stress responses. Only seven out of 22 variables examined on the rabbit blood showed statistically significant changes in response to the electrical stimulation of 40 v of rectangular pulse. In the other experiment, it was found that handling of animals and attachment of electrodes per se provoke a remarkable stress response on animals. Probably on this account, the electrical load applied to animals resulted in not so distinct effect as to produce statistically significant differences among the values obtained at 20, 40 and 60 v on four variables. Among positive stress indices obtained from the experiment on rabbits, the serum levels of 11-hydroxycorticosteroids and free fatty acids were suggested to be especially useful for the study of emotional stress responses.
Biochemical responses of human subjects to mental tasks were examined. Three types of arithmetical calculation tasks were assigned to subjects as mental tasks. Kraepelin-Uchida's task for 1 hr caused no difference in the blood variables of subjects from their control levels. Addition task" and "addition-subtraction task" were assigned to subjects by using a signal indicator which was able to display a pair of figures from 3 to 9 at regular paces. Even at a higher pace, "addition task" of 20 min also failed to change the control levels of the variables. On the other hand, "addition-subtraction task" of 20min provoked significant changes in the serum levels of 11-hydroxycorticosteroids and albumin at a lower pace of the task, and in addition to these free fatty acids and protein at a higher pace of the task comparing with the control levels. Moreover, there were the differences between the two paces on the serum levels of protein and albumin. During the recovery period of 20 min, valuable returns toward the control levels were observed in the serum levels of 11-hydroxycorticosteroids, protein and albumin.
It has been well known from experience that among the divers, who were ap-parently healthy without any troubles, two types, strong and weak were present. A strong diver is one who is not susceptible to decompression sickness, and a weak one is the converse. Generally, old people and people who are fat are not suitable for diving work. Decompression sickness might be avoidable if the divers could be clas-sified into the two groups by some scientific methods. For finding out the method we examined preliminary about 20 divers and 10 normal people biochemically, and the results were compared with a self-rating by the divers themselves into strong and weak. The results were as follows : (a) Total cholesterol content in the blood of the divers were in the normal range, although that of weak divers were larger than the strong. (b) Free cholesterol content in the blood of divers was about one-third of that of normal people. (c) Ester cholesterol of weak divers was larger than strong ones. (d) The velocity of nitrogen gas uptake by the blood of the weak was larger than the strong. (e) Oxygen affinity of hemoglobin molecule of most divers examined showed a marked raise. (f) In most divers examined, pH down and pCO2 increase of the venous blood were observed. One year later of this study, nearly same examination was carried out on many divers in Japan. The results will be reported in a next paper.
Organic solvent evaporated and contaminates ambient air. Identification of the volatile solvents in commercial materials has been deviced using an evaporation technique by infrared spectrometry. Sample is put in a reservoir made by glass tubing and evaporated into a gas cell. The observed spectrum by drastic evaporation into the gas cell evacuated at 1 mm Hg or by evaporation standing for long time interval is different from that by gentle evaporation evacuating with water suxion pump. Comparison of both spectra make identification easy even through particular separation is not performed. Spectrum of vapor is specific in its pattern of charac-teristic bands in many cases and that pattern can be used to identify the component. Furthermore the more volatile component increases the more the vapor concentration in the gas cell and therefore gives rise to the bands in higher intensities than those of less volatile compound. By using those phenomena, the present technique may be suitable to identify volatile components in the organic solvents.