This study presented the available effects of Source Derivation (SD) method for detecting the focal EEG, from the model experiments which were compared the traditional monopolar derivation with SD method, and also from the clinical recording for the patients, Signal dipole and EEG noise dipole embeded in a spherical volume conducted covered with three layer shells corresponding to neural tissue, skull and scalp, were used for the model. The following conclusions were obtained. 1) It was proved by the model experiment that SD method was useful for the detection of focal signal dipole potential on cortical surface. 2) SD method was useful to detect the signal not only in the cortical surface but also in the deep cortical area, when the reference electrode angle of SD method was smaller to the active electrode (α=10°-20°), that is, the distance of electrodes on scalp surface was about 1.6-3.2cm. 3) SD method was applied to the patients with focal spikes. The localization of the focal spike was more clear than the traditional ear reference monopolar recording. S/N to back ground EEG also was improved very well. 4) Identification of the location generated of primary responses in somatosensory evoked potential (SEP) by electrical stimulation of median nerve was tried by using the SD method with intererectrode distance of 2cm, and consequently the central sulcus and cortical primary sensory area were identified from the phase-reversal of SEP on the scalp.

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To realize the multivariable control of the circulatory system driven by the left ventricular assist device (LVAD), the responses of the circulatory system to the control inputs of the pneumatic drive unit has been analysed. The results from the mock circulatory system revealed that manipulation of the systolic duration (ω) and the systolic delay (τ) enables us to control the outflow from the LVAD (LVADF) and the aortic pressure (AOP) independently to a certain degree. In the case of the adult goats whose cardiac functions were supressed by Inderal (propranolol), LVADF and AOP could be controlled by changing τ. However, the effect of the variation of ω or τ on the cardiovascular dynamics was smaller than that of the mock system. This might be caused by a compensatory mechanism of the cardiovascular system using the neuronal and humoral feedback.

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A computer simulation system employing the finite element method was developed to study the effects of torso inhomogeneities on the distribution of the body surface potentials. The torso model is constructed from the X-ray CT images of the patient. The torso is divided into 4992 tetrahedral elements keeping in view the fact that the potential radiates outwards from the dipole conforming to the inverse square law. The CT value is determined at the center of gravity of each of the tetrahedral elements. The CT values help us determine accurately the shape of the body and idcntify the inner organs, their shapes and relative positions. The simulation maps for homogeneous and inhomogeneous models were derived by placing a dipole at various positions in the model of the heart. The cross correlation coefficient between the two maps was found to be as low as 0.72 when the dipole was placed near the boundary of the lung. The effect of inhomogeneities due to the conductivities of inner organs on the simulated body surface potential maps was studied for various organs. The effect due to lung was most pronounced—it increased the maximum and reduced the minimum values by nearly 25%. This system will help us in better understanding of the cardiac disorders.

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Recently we have designed and constructed a simple apparatus for continuous recording of sweating rate utilizing a hygrosensor of electrostatic capacity type. However, there still remains the following probrems in the apparatus. (1) Output voltage of electrical circuit in a capsule is drifted by changes of skin temperature. (2) Sensitivity of the sweating ratemeter is modified evaporated water loss depending on changes of environmental temperature, because a hygrometric sensor equipped in the capsule can detect changes of relative humidity. Two technical changes are adopted to improve the above mentioned disadvantage. One of them is a dummy erectrical circuit for compensating the thermal drifts of skin and environmental temperature. The other is a micro-computer system which can calculate the relative humidity to the absolute one. Thus, reported in this paper the construction and performance characteristics of this new apparatus, comparing with the respective data of the previous apparatus.

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In recent years, microsurgery or the conducting of surgical operations under a microscope, has become popular in ophthalmology, otorhinolaryngology, orthopedics, brain surgery and so forth. In oder to conduct the resection and suturing of minute nerves and blood vessels under a microscope in such operations, it requires careful attention and a high level of concentration. Especially, corneal microsurgery demands intensive care so that remaining tissue might not get damage hinder transparency for vision. To help surgeon conduct such an operation with more safety and accuracy, robotics, image processing and measuring techniques and laser technology can be employed. We think that non-contact cutting method using excimer laser is more suitable for this operation to obtain a clear-cut edge. Excimer laser is currently tested for corneal surgery on clinical level, but problems of positioning of the cornea and its three dimensional surface measurement still remain. We have developed a laser scanning and cutting system which gives us high versatility of cutting lines and high accuracy of positioning of the beam after three dimensional surface measurement of the cornea. Designation of cutting line is easily done on monitor screen that superpose the mesured surface on the video image. Irradiation conditions of excimer laser for resection were obtained through experiments with porcine corneas. In this paper we describe the configuration of the system, measuring method and interactive software which simulates an operation on a monitor and also experiments to get irradiation conditions of the excimer laser. Some results of measurement and corneal resection are also presented and discussed.

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