A new flicker test apparatus has been developed, by which measurements of critical flicker frequency (CFF) can be repeated stably in a short duration, and the method of measurement using this apparatus was investigated. A microcomputer used to control the flicker frequency, the treatment of the response switch and the saving data in this apparatus. Controlling flicker frequency up and down repeatedly, the two measured curves were obtained at one time, the one was the CFF curve by the ascending method (fu-CFF), and the other was by the descending method (fl-CFF).
The curves showed patterns whose initial values were high, followed by gradual decrease over a short period of measurement. The fl-CFF of females were higher than that of males, the drop of CFF during the test of the females were smaller than that of males. According to the experiment loading the task by the Kraepelin test, the changes were recognized in the initial CFF which corresponded to the mean value by the conventional method, in the fluctuation of CFF, and in the difference between fu-CFF and fl-CFF(hysteresis). The remarkable change of the drop of CFF with no change of the initial CFF was found in one case.
The changes of hysteresis, the fluctuation of CFF and the drop of CFF with the task were obtained, which could not get by the conventional method. Therefore, the method of measurement using the Continuous Flicker Test Apparatus considered to be useful as a new functional test for evaluating human stress resulting from work.

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In this paper we propose the method constructing the evoked potential model in the time domain, in order to express the feature of the evoked potential quantitatively by the wave form decomposition. The model consists of a parallel combination of the second-order system with time lags, and the model parameters are determined to minimize the weighted modeling error by the Fletcher-Powell method in the time domain. This model enable one to construct the evoked potential model laying stress on a certain component of the evoked potential, and can be applied to various evoked potential. When applying the method to the somatosensory evoked potentials, we can find a common component in the scalp topography of the decomposed wave form and the decomposed wave form corresponding to the medical finding.

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The possibility of expansive splitter used in general industry for the application to lithotripsy was evaluated experimentally. The result were as follows,
1) Expansive stress generated by expansive splitter was enough to cause all urinary stones to crack.
2) Urinary caluculus 35×30×30mm in size was fragmented within 30 minutes.
3) The spherical model caluculi 30mm in diameter were fragmented in a condition that the boring size was more than one fifth of the diameter and the boring depth was more than a half of it.
The results suggested that expansive splitter could be applied clinically to fragment urinary caluculi after some improvements.

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Automatic real-time sleep staging system has been fabricated for the purpose of chronobiological study. The system is supported by a conventional personal computer and can monitor sleep state for about ten hours continuously. In this system, EEG at C₃ lead is fed to a set of IC filters and is divided into seven frequency bands. Output powers of these filters are used as components of feature vectors for the discriminant analysis of sleep stage. This discrimination is performed every 30sec and the final staging is obtained after corrections using contextual informations together with EOG and EMG. The results of the sleep staging with this system showed more than 70% agreement with those of visual inspections based on Rechtschaffen and Kales manual. Furthermore, we found that the principal componenet of the multiple-discriminant analysis can be used as the index of the depth of sleeping and using this index, we can identify REM period automatically with 85% agreement. As conclusion, this system well works for chronobiological study. Some results on REM rhythm will be reported in succeeded paper.

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By making use of the correlations among the potentials measured at different sites on the body surface, the number of electrodes required to reproduce the body surface potential map (BSPM) can be reduced as Lux et al. had pointed out. In the present paper, we have introduced a method in which the BSPMs are divided into several classes according to the direction of the vectorcardiogram in order to increase the accuracy in the potential estimation.
The present method was applied to the BSPMs measured from 75 subjects with various heart diseases including normal ones, and the results were compared with that in the Lux method. To evaluate the estimation error, the maximum deviation between the measured and the estimated BSPM as well as the conventional correlation coefficients and the RMS error were used. Judging from all these error estimations, the present method is superior to the Lux method. It is also shown that there was a simple relationship between the correlation coefficient and the RMS error. Furthermore, the effects of the electrode displacements on the potential estimation are investigated numerically by computer simulations.

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Up to date, thermocouple sensors have been applied in temperature monitoring during hyperthermia. However, using thermocouple sensors, infection and metastasis may be caused by inserting and removing the sensing wires. We have therefore developed a completely implantable temperature sensor which does not require a battery. The sensor consists of a coil which transmits signals to the receiver coil outside the body and a quartz resonator. And its resonance frequency varies with ambient temperature. The resonance frequency to the corresponding temperature can be measured from the outside of the body.
Heat accumulates not only in the cancer but also in the normal tissue with RF hyperthermia system. Therefore, a multichannel thermometer with implantable sensors having different resonance frequency each other has been developed in the present.
Sensors are implanted at various sites and sensor coils are gathered in a bundle pairing with a receiver coil. Then, the resonance frequency of sensors is measured in order. If the difference among the resonance frequency of sensors is higher than 100kHz, errors caused by interference among sensors will be negligible. The temperatures at 10 points can be sequentially measured with this thermometer and the required time is about one second per channel.

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This paper presents a new technique for high-speed digital image recording for the observation of vocal cord vibration. Observation of the vocal cord vibration has generally been performed by using a high-speed motion picture and a stroboscopy. However, the high-speed motion picture requires special equipment and is not suited for practical clinical observations. Stroboscopy has inherent limitations in that irregular vibrations in the pathological cases can not be traced precisely. The system developed in the present study consists of an oblique-angled solid endoscope, a camera body containing an image sensor and an image processor. The output video signal from the image sensor is fed into the image processor through a high-speed A/D converter. Stored images are then displayed on a CRT monitor. Frame rates of 2000/sec and 4000/sec are realized for the images with 100×36 and 100×17 picture elements, respectively. A similar system using a fiberscope was also developed. Although images by the fiberscope are darker, a frame rate of 2000 per second was achieved for the images with 200×14 picture elements. The system makes it possible to observe vocal cord vibrations during the consonants. Compared to the ordinary high-speed motion picture system, the present systems are compact and enable flexible data collection including recording of pathological vocal cord vibrations. A compact unit for clinical use which consists of a small-sized image memory combined with an ordinary personal computer was also constructed.

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A method and results of the analysis of the regularity in the distribution of REM episodes across nights are presented. REM episodes in the sleep of consecutive nights were measured using automatic sleep staging system reported in our previous paper. In these measurements, subjects spent every day in normal conditions at the longest for 21 days.
Five types of models of REM-NREM sleep distributions have been tested; (1) a clock time dependent model, (2) a consistent phase shift model across nights, (3) a sinusoidal phase changing model, (4) a sleep-onset dependent model, (5) a model of no systematic phase shift.
We have obtained the best fit of data to the model (3). Timing of REM episodes shifts almost sinusoidally with a half or an hour amplitude and 14-15 day period. This sinusoidal shift implies the relative coordination due to the entrainment of REM rhythm by 24 hours L-D cycle. The difference of amplitude among subjects is considered due to that of the strength of the entrainment. Thus the analytical method reported here will contribute to the quantitative study of properties of human sleep especially of REM-NREM cycle.

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