In the past, some electroencephalogram (EEG) models have been suggested in order to analyze the EEG. Almost all these EEG models have rather complicated structures and include a great many parameters. They are defective in that it is difficult to find the correspondence between the model parameters and the findings of the doctors.
In this paper, we propose a simple EEG model expressed by the sinusoidal waves with the Markov process amplitude, which overcomes these defects. This EEG model can aptly represent the features of the EEG in terms of a few parameters, and it is easy to find the intuitive correspondence between the model parameters and the findings of the doctors. To determine the parameters of the EEG model, the method for optimally approximating the spectrum with a distribution function in a frequency domain is used. In the latter half of this paper, the validity of the EEG model it both a frequency domain and a time domain is shown, and this EEG model can then be applied to quantitatively express the features of the EEG. Some examples are investigated herein.

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In order to clarify the mechanisms of cardiac muscle contraction, sarcomere dynamics in isolated cardiac muscle was analyzed by the laser diffraction method and the servo-control system. In muscle isometric contraction, a considerable internal shortening of sarcomere occurred during contraction. In sarcomere isometric contraction, tension developed very rapidly to the plateau level and then declined exponentially. Sarcomere force-velocity relation for shortening was a hyperbolic curve. The force generated by a cardiac sarcomere during lengthening increased towards a constant value when the lengthening velocity became larger than 2μm/s. The sarcomere became less able to shorten and more resistant to lengthening with the increase of the time after stimulation pulse. Isotonic velocity transients were observed only when the sarcomeres were held isometrically before the isotonic release. Deactivation by active shortening was observed and the extent of deactivation increased with increase of shortening velocity and the time after stimulation pulse.
A kinematic cross-bridge model, which relates the formation and degradation of the cross-bridge with the force generated by the stiffness of the cross-bridge, could explain the major characteristics of cardiac sarcomere dynamics. The cross-bridge model with parameters estimated from force-velocity relation predicted that the stiffness within cross-bridge was linear and that its size was 5nm in length.

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This paper presents a system for displaying three dimensional images of human brain for operation planning.
This system includes the following functions: display of cross-sectional images along tilted plane or the vertical cylindrical surface reconstructed from a given CT image sequence; 3-D display of the ventricle and lesion (tumor and hematoma etc.) surfaces; display of the partially eliminated skull and the translucent skull surface; display of coronal sutures superimposed on the skull surface.
This system is expected to be useful not only for surgical planning, but also for education in medicine.

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The tracer method was utilized for the quantitative analysis of the flow field within artificial heart (AH) using mock circulatory loop. The flow behavior was analyzed with a numerical method. The length and location of the particle paths on the flow-visualizing picture were measured with a digitizing tablet and the velocity vectors in several phases were computed from these data. The unknown velocity vector at each point of the mesh of the square grid pattern drawn tentatively on the photograph, was deduced from several adjacent velocity vectors by the least square method. The mesh point values of the stream function and vorticity were calculated from the mesh point velocity vectors by means of iterative integration and finite-difference approximation. The results thus obtained were displayed by a plotter using the linear interpolation method. It was concluded from this study that: (i) the current within AH flows along the inner surface and stagnates at the inlet during the filling period; (ii) presumably the circulating current removes the blood, and suppresses the formation of thrombus within AH; (iii) there is a need to modify the contour of the inlet portion of AH, because the blood flow thereabout stagnates; (iv) our flow-visualization and quantitative analysis proved useful to develop more efficient and thromboresist AH.

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Bone X-ray images have been used mainly for the qualitative analysis or the morphological measurement of bones. This paper proposes a method for quantitative characterization of femur X-ray images using a spectrum analysis technique. This method characterizes the trabecular pattern by the spectra (spatial frequency distributions) of trabeculae in the X-ray image. Though some methods have been proposed for the characterization of trabecular patterns, they were for the dried bones taken outside the body, and, therefore, could not easily be applied to the clinical. X-ray images. This method deals with the X-ray images of the bones in vivo with a view to clinical use.
As a spectrum analysis technique, Maximum Entropy Method (MEM) is used instead of the commonly used FFT technique. First, this method was applied to the X-ray image of the femoral head specimen (dried bone) to verify the effectiveness of this principle. The obtained spectra agreed well with the results of visual observation. Then, using this method, the trabecular patterns in clinical X-ray images were analyzed. Although the femora were in the body, the obtained spectra were found to reflect the characteristics of the trabecular pattern well. Particularly, the positions of spectral peaks stand for the line density of the trabecular pattern. In order to examine the usefulness of this method, it was applied to 11 clinical X-ray images of femoral heads varied from normal to severely deteriorated by osteoporosis. In the comparison between the line density estimated by this method and the diagnosis given by orthopedists (6 doctors), the following results were obtained. With the conventional grading method, large individual variations are inevitable due to subjective observations. And there is a close correlation (γ=0.86) between the line density estimated by this method and the relative order given by the orthopedists.

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We have developed a temperature measuring system with an implantable sensor for the hyperthermia application. As the sensor does not require a battery, it can be implanted in a body for a long term and used repeatedly.
The sensor consists of a coil and a quartz resonator whose resonance frequency varies with ambient temperature. The resonance frequency of the sensor can be measured sensitively from outside of the body by applying frequency modulated RF electromagnetic field. A microcomputer in the measuring system converts the resonance frequency to the corresponding temperature. Furthermore, the temperature data are displayed on a CRT display and stored in a floppy disk automatically.
With this system, we have measured the temperature ranging from 35 to 50°C with errors less than ±0.1°C. The system operated properly while it was heated with 500W RF electromagnetic generator.

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