It has been reported that the mode of muscle activity is concerned with the power spectrum pattern of surface electromyogram (EMG), in so far as the signal is steadily ergodic in the stochastic process. In this paper, a new deterministic method is proposed for characterization of the non-stationary EMG which varies dynamically in time.
An AR (auto-regressive) model is suitable to explain the almost periodical EMG. When the parameters of this model are calculated by the least square estimate (LSE), it is important that the (i+1) th order of forward and the (i) th order of backward prediction error vectors be orthogonal to each other. Therefore, the non-stationariness of EMG is characterized from the looseness of the orthogonality, if these vectors at any interval are obtained as the outputs from the standard filter (SDF), which is defined in a stationary interval by the LSE. Practically, {J_FBEO⁽ⁱ⁾}, which resembles the similarity function, is used for characterization.
When an SDF was prepared with the masticatory EMG during the maximum clenching, decrease in the order of AR model appeared for 50%, 25% clenching. At the onset and the ending phase of EMG during the tapping movement, the order also decreased gradually toward the silent phase. The physiological meaning of the order has not yet been clarified, but this method may be useful to understanding the transition period of EMG, which is concerned with excitation and inhibition.

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Actual condition of patients with rheumatoid arthritis should be known to attending doctors for the adequate management of the disease. For this purpose, a portable computerized disease condition memory system has been developed to record the patient's pain fluctuations and physical activity in daily life, both at home and during work.
This system is a kind of small battery-driven computer system (10×7×1.8cm, 200g) and is equipped with four button switches on the upper side and a mercury switch inside it. In practice, the pain fluctuations and the duration of morning stiffness are recorded by patient's pressing of the corresponding switches. Meanwhile the mercury switch serves as a kind of shock sensor and the physical activity of the patient can be recorded by wearing this unit all day long. The continuously recordable time is more than two weeks.
At the first study, rheumatoid activity was evaluated by comparing the data obtained by this new recording system with the Lansbury index widely used now. Actually pain fluctuations and physical activities were correlated with changes in the dosages of drugs, such as corticosteroid or anti-inflammatory agents. The result showed that the data obtained by this system became better or worse in response to the drugs dosages, even though the Lansbury index did not change.
These results indicate that minute changes in the disease condition can be followed by this system, and in this sense the effectiveness of this system in clinical application has been demonstrated.

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Using the previously developed walkway system, temporal and distance factors of normal gait, such as step length, single support duration, double support duration, were collected from six male and female adults and analyzed. In this study, multifarious experiments were performed in order to examine the way the gait pattern changes under variable conditions, and the following results were obtained.
From statistical point of view, the significant differences between right and left were recognized in any measurement variables in all subjects. Interrelations between two variables in each successive gait steps were found to be feeble. The characteristics of gait patterns in such cases as starting and stopping, or stepping into a square frame were obtained. The coefficients of variation and the asymmetry indices over a range of walking speeds were introduced. And it was found that both developed the same tendencies as the walking speed increased.
Some experimental equations on gait were introduced, and these equations clarified sex differences in gait patterns. For instance, velocity relatively depended on step length for the male, while that of the female depended on cadence. Relation between the relative stride length and cadence over different speeds were examined, and sex differences were shown, too. However, sex differences disappeared in case of metronomic syntonized gait.

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The effect of valve orientation on the flow development and the hydrodynamic characteristics of prosthetic mitral valves has been studied by using a total mock system of human left heart and aorta. The system replicated the geometry of human left heart and aortic arch having a pertinent hydraulic load of the systemic circulation so that the flow process simulated physiological pulsatile conditions. Simultaneous flow visualization study was carried out to investigate the dependence of valve orientation on the flow development in the left ventricle. Five different mitral valves, Björk-Shiley spherical disc, Hall-Raster pivoting disc, St. Jude Medical, Carpentier-Edwards porcine xenograft and Ionescu-Shiley pericardial xenograft, each having an annulus diameter of 29mm, were assessed as to how the valve insertion should be oriented.
Total hydrodynamic evaluations regarding effective orifice area, diastolic energy loss and turbulent formation suggested that the major orifices of Björk-Shiley as well as Hall-Kaster valves should be oriented towards the parietal wall of left ventricle. As for the St. Jude Medical valve, it was found advisable to direct the two pivot guards towards the septal and parietal walls of left ventricle respectively. Regarding the two bioprostheses, the orientation placing one of the three leaflets on the anterior side of mitral position was also found advisable. These findings have been found to be in good agreement with the clinically and empirically arrived approvals of valve orientation.

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An objective assessment of the character cognitive process of human is presented, using statistical analysis of evoked potentials.
Alphabet patterns and random-dot patterns randomly chosen from among large varieties respectively are successively displayed in random order. Each pattern is displayed as 30ms flash at an interval of several seconds. Every EEG data is picked up for about 1 second, and 40 data of the same category are recorded. From each data optional 127 ms-length segment (128 samples) corresponding to a center latency is taken is put through Hanning window processing and fast Fourier transform to obtain the power spectrum whose fundamental frequency is 7.8Hz.
Then the two groups of 40 power spectrum each of the same center latency are put through discriminating analysis. Then examination is made to see in which frequency component and at what latency appreciable discrimination occurs. A method to evaluate the degree of contribution of each spectral frequency to the discrimination is also introduced, taking into account the fact that the power spectrum is correlated. The result of testing a healthy subject showed that there was an appreciable discrimination at 40-60Hz and latencies of around 130ms and 500ms. These are unavailable from conventional mean addition process. Thus, statistical analysis of wide frequency range VEP is one of the important directions for further study of evoked potential in general.

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A CAI (Computer Assisted Instruction) system using a personal computer has been developed with the object of assisting the students to acquire the ability to undertake logical diagnosis of complicated cases of arrhythmia. A simulation method with a model of the impulse formation and conduction system of the heart, which we have made, is used in this CAI system. A simulated arrhythmia (ECG pattern) is given on a CRT display unit with simulated series of action potential of four pacemaker centers and the “ladder diagram” of impulse formation and conduction, which shows the mechanism of that arrhythmia.
As learning takes place by following indications in dialogue style in Japanese, even students unfamiliar with computer operation can utilize this CAI system without trouble. This system has three learning modes. The first mode is for acquiring of fundamental knowledge concerning the anatomy and electrophysiological properties of the impulse formation and conduction system of the heart. The second is the mode in which students can learn ECG patterns and mechanisms of 23 common cases of arrhythmia as well as the effects of autonomic nerve stimulation and of various drugs on these arrhythmia cases by the simulation method. The third is the mode in which students can advance their knowledge of arrhythmia in the process of simulating desired cases of arrhythmia by the trial-and-error method with changing parameters and irregularities given to the simulation model. Using this CAI system, students can learn about arrhythmia efficiently and interestedly.

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