The type of fluctuation of Speech Rhythm (TFSR) for CD sounds of an audiometry (CDA), for Japanese “Noh” (NOH) were determined using Zero Crossing Analysis. And TFSR for reading for 9 normal adults (NAs) were also done. TFSR for the NAs was 1/f-like. However, for one NA who complained of uneasiness was 1/f⁰-like. TFSR for CDA and NOH was 1/f-like. Two normal adults were assigned the task of binaural ear occlusion, binaural masking, laying with face up and nose holding. TFSR for both binaural masking and laying with face up differed from the eight normal adults (NAs). The suppression for the respiratory or the auditory feedback effects TFSR in low frequency. The function of articulation will effect TFSR from the frequency of 1Hz to 10Hz.

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With X-ray CT images of the head, it is difficult to correctly classify pixels in regions of brain and skin, as the CT-value distributions for these tissues overlap. We present a method of separating the distributions, allowing brain tissue to be distinguished from skin and other tissue, by selectively shifting brain CT values in histogram space. We briefly describe the volume rendering process, and in particular the classification step (corresponding to the segmentation step in convensional surface rendering) in which our new algorithm is implimented. The algorithm, selective CT-value shifting, functions as follows: Brain regions are separated from other areas using image masking. Shifting the CT values of these regions in histogram space then allows brain regions to be distinguished from other regions the renderer. Finally, in order to demonstrate the effectiveness of the algorithm, we present rendered images based on Head X-ray CT images.

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Recent progress in volume rendering technique has drawn much attention and expectations to its achievements. Compared to surface rendering, however, few researches have been done on volume rendering, especially on its application to three-dimensional image analysis. In this study, we have developed a modified ray-casting technique for three-dimensional image analysis in volume rendering. This technique is based on assigning appropriate opacities to different tissue regions and on specifying areas involved for rendering. Because of difficulty in specifying regions manually, we have also introduced our own GUI (Graphical User Interface) system written in Delphi language. With this technique one can remove bone from volume-rendered images or superimpose tissues such as brain and skin. Computer simulations on clinical multi-slice X-ray CT images are performed to test the feasibility of this newly developed technique.

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This paper showed the biological effect of a static magnetic field using the adhesion of pathogenic Escherichia coli to HeLa cells. The number of adhesive E. coli was increased by the exposure of the static magnetic field under the mixed incubation. There was also the dose dependency on the intensity of static magnetic field in this phenomenon. In order to analyze this phenomenon, the growth enhancement of E. coli caused by the static magnetic field exposure and the changes of susceptibility in HeLa cells due to the static magnetic field exposure were examined respectively. However, those changes were not observed in both cases. The phenomenon might be caused in order that the static magnetic field suppressed the movement of E. coli in a culture solution. Based on the speculation, viscosity was added to the culture solution of E. coli to suppress the movement. The adhesive number of E. coli to the HeLa cells increased under this condition. We also examined effects of ELF (10, 30, 50Hz) magnetic fields on the adhesion of E. coli to HeLa cells. The decrease in the adhesive number of E. coli was observed in the 10Hz magnetic field. In cases of 30Hz and 50Hz magnetic fields, however, the clear difference was not observed. Escherichia coli have negative charges on the cell surface. Lolentz force may be given while they move in the static magnetic field. Therefore, we speculate that the Lolentz force induces the enhancement of adhering bacteria to HeLa cells.

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The aim of this study is to visualize the imaging of temperature distribution inside the human head by a noninvasive technique. Information on the electrical properties of the human tissue can be obtained by capacitance measurement using electrodes placed around the body, the permittivity of which has a great dependency on temperature. This paper describes a method of imaging of nonhomogeneous equivalent permittivity distribution against that of temperature distribution. Here we propose a new measurement method of capacitance between a pair of measurement electrodes with supplementary electrodes on which the potential of each measurement electrode is impressed under various combinations of supplementary electrodes. Images of nonhomogeneous equivalent permittivity distribution formed with a homogeneous phantom containing agar-agar are reconstructed by a regularization method of reconstruction algorithm based on the modified Newton-Raphson method. The proposed new capacitance measurement method was shown to function for the imaging of nonhomogeneous equivalent permittivity distribution, though the measurement procedure and system require further study.

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The pulse wave velocity (PWV) has been used clinically as an index in order to evaluate arterial distensibility and the grade of atherosclerosis quantitatively. But the conventional method of PWV measurement has relied upon averages between the carotid and femoral arteries, inapplicable to any specific regional site. We propose a new method using Doppler techniques which can measure PWV accurately over closely spaced sampling sites just a few centimeters apart. We investigated the accuracy of this system at an ultrasonic frequency of 7.5MHz. We employed a Pulsatile flow circuit model in which the arterial wall was simulated by silicone tube. Local pulse wave velocity employs a signal processing procedure to increase the coherence between these two Doppler signals (5cm, 3cm, 2cm, 1cm) and involves the complex cross correlation analysis of these processed signals. We investigated the influence of blood flow pattern change when the pulse propagation length is fixed at 3cm. The longer the distance traveled, the longer the propagation time of the pulse wave. Upon examination of the standard deviation of PWV at each measured distance, we found a significant difference (p<0.05) between 1cm and 2cm. Changes induced in blood flow pattern did not affect pulse propagation time. The combination of noninvasive Doppler ultrasonography for measuring pulse wave propagation velocity over very short distance of more than two centimeters and complex cross-correlation analysis give us the potential means for evaluating local arterial distensibility.

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Unwanted temperature rise at muscle-bone interface has been one of the major problems during ultrasound hyperthermia treatment. In this study, we examined the alteration of temperature distribution caused by the existence of this interface from both computer calculation and model experiment. It has been said that this heat generation at the surface has a close relationship with the beam's incident angle. Ultrasound penetrates inside of a bone in two different waveforms, longitudinal wave and transversal wave. And the transmission factor of these two waves differ in great deal with the alteration of the incident angle. We first calculated the transmission factor as a function of incident angle from equation which was derived from the interrelationship of particle velocity and stress inside of a bone. Then, we obtained the sound pressure, SAR distribution and the tempeature rise distribution. From both theoretical and experimental results, the incident angle dependency of the interface heat was confirmed. And it is found that the mechanism of the heat generation relies to the incident angle, too. When the incident angle is less than the critical angle of the longitudinal wave, the main cause of the temperature elevation is due to the absorption of the longitudinal wave in the bone. As the angle gets larger, the reflection wave becomes the general origin of this unwanted heat. When the incident angle is larger than the critical angle of longitudinal wave, transversal wave becomes the major factor of the heat generation. Incident angle larger than the critical angle of the transversal wave produce no temperature rise due to the absorption of the bone.

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Near infrared imaging is a medical imaging modality in which red and near infrared light is used to probe biological tissues. Images are obtained by mapping the absorption coefficient of the tissue. Light, however, is strongly scattered by tissues, and scattering of light makes the image reconstruction very difficult. Realization of clinically viable near infrared imaging techniques depends on the development of reliable and fast methods of obtaining inverse solutions of the radiative transfer equation. In this paper we describe a technique for obtaining images from a limited number of continuous wave scattering measurements using homogeneous and inhomogeneous solid cylindrical phantoms. We propose the use of the zooming method as a way to improve the resolution of the images which are obtained by a quasi-Newton's method for the inversion procedure.

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In order to investigate the technique of cardiac assistance using skeletal muscle (Cardiomyoplasty) we are developing an implantable skeletal muscle stimulator that responds to muscle fatigue. The stimulator has a resonant circuit to transmit internal information using the carrier waves from the external program head. The stimulator can also control the synchronization ratio automatically using the peak value of the impulse response from an acceleration sensor to estimate muscle fatigue. In this series of animal experiments we verified the functions of both data transmission by the resonant circuit and automatic control of the synchronization ratio. Our results suggest that the stimulator can be used to automatically control muscle stimulation in Dynamic Cardiomyoplasty.

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Event-related potentials, as well as reaction time and percent correct of performance, were measured and analyzed in six healthy subjects during the phonemical comparison between Hiragana and Katakana letters (Japanese phonogram) which were visually presented simultaneously. Two different tasks were designed in the experiments. One was the task called “silent reading+matching” task which required the processes of matching, judgment after silent reading of the presented letters. The other was the task called “silent reading” task which only required the silent reading process. The reaction time in silent reading+matching task was significantly longer (p<0.01) than that in silent reading task. In the two tasks, the following three ERP components were commonly observed, a large positive component Pa peaking at 190ms centered at the left and right posterior temporal scalp areas, a positive component Pb peaking at 320-345ms centered at the center and the middle of the frontal scalp area, and a negative component Na peaking at 550-575ms centered at parietal scalp area. In addition, a positive ERP component Pc peaking at 1300ms was observed centered at the left temporal and left posterior temporal scalp areas only in the silent reading+matching task. For three subjects, measurements of the ERPs and the time of “starting silent reading=RT_srd, ” “finishing silent reading=RT_erd, ” “finishing matching+judgment=RT_rm” were made changing the number of letters. The RT_erd, RT_rm and the peak latency of the ERP component Pc were increased with the increase of the number of letter, whereas the RT_srd and the peak latency of the Pb component were constant.

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In this paper we describe personal identification method by using ECG signals obtained from the bathtub ECG. Difference of ECG signals between subjects was used as an index of personal identification. The measured ECG was processed by the wavelet transformation to reduce, the input data of neural network. The network was trained by the back propagation learning algorithm. Personal identification was achieved 89% classification rate in 8 subjects who don't have blood relation. And 92% classification rate was achieved in a family which have 5 members. This method is available to make personal identification in bathing monitor.

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This study presents a mathematical model for the physiological fluctuation of the center of gravitation of the human body. While we are standing, the center of gravitation is inconsiderably fluctuating, and the movement is considered to be a two dimensional Gaussian process. At first, we had expected that our model of the fluctuation could be obtained by modifying the Arato-Kolmogorov-Sinai model for magnetic north pole, but we found it is not the case. The back and forth component of the fluctuation is regarded as the main part and behaves as an Ornstein-Uhlenbeck process. Being interfered with this component, the right and left fluctuation may be viewed as higher order Gaussian Markov process. We can also give a physiological interpretation to this model.

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A method for quantitative interpretation of slow wave characteristics was developed and evaluated. Slow waves which consist of theta and delta waves are typical for abnormal background electroencephalogram (EEG) activities, and therefore have a great significance in order to interpret the awake background EEGs. As the parameters for expressing the characteristics of the slow wave, following four items; duration, electrodes, relative amplitude and rhythmicity were treated. The equations for defining the characteristics of the slow waves were determined in accordance with the process of visual interpretation of an electroencephalographer (EEGer). The developed method was applied into 21 subjects whose data were selected as artifacts free and fully awake EEG records. Results of the quantitative slow wave interpretation were in good agreement with the visual inspection done by an EEGer. This method can be adopted as a part of the automatic EEG interpretation system which was previously proposed by the authors, and it will be an expansion of the proposed system.

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We have been developing the Hyper Hospital, a network based VR mediated telemedicine system of which principal purpose is to re-build patient-centered medical care system. In the present study, an attempt to extend the Hyper Hospital system to a satellite communication based network of multi-media information using Internet protocols with the WWW interface is reported. Data transmission speed was measured under various conditions and the satellite network was shown to be suitable to the Hyper Hospital network.

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