This paper describes that a neural network, which consists of neurons with piecewise–linear sigmoid characteristics, is able to approximate any piecewise–linear map with origin symmetry. The neural network can generate "deterministic diffusion" originating from its diffusive trajectory.

A support system for hepatectomy that allows segmentation of the liver interactively and directly on 3D images was developed. Intuitive 3D images of the liver and its vessels and tumors were drawn with an improved volume-rendering method. Regions supplied with blood by each branch were interactively identified. 3D segments were defined directly on the images using a mouse and excisions were estimated from these interactive inputs.

This letter shows that VEPs can be easily measured by using color cards as the color stimulus, and that the responses evoked by a difference in chroma could be described largely by the value of the first principal component in principal component analysis.

We derive the eigenvalue constraint for a neural network with three degrees of freedom. The result implies that the neural network needs a neuron with variable output function to generate chaos. It is also shown that the neuron with the special characteristics can be constructed by ordinary neurons.

Cardiac output can be measured from the rate of absorption of soluble inert gas across the lung using an electric model of human body suggested by W. Mapleson. Step response of the model becomes the sum of exponentials. Cardiac output is estimated from time constants and amplitude coefficients of the response. System for the measurement of the cardiac output which is based on this theory will be introduced below.

System for the measurement of the respiratory response of human is introduced. This system has the facilities to supply the air which is mixed with CO2 or N2O. The subject inhales the gas of which contents variation can be controlled by the program. The system also measures the respiratory response of the subject which is caused by the changes of atmospheric circumstances, i.e., CO2 inhalation and records data. To check the concentration of agent gas according to the program, micro computer is used. Flow volume of expired gas, heart rate, concentration of supplied gas and that of expired gas are collected. One of the experiments in case of CO2 inhalation is shown. In this experiment the subject inhales the air which is mixed with CO2. Its pertition is 5% of the total volume.

It is known that psychotropic compounds give change to evoked response of human. A system for the Auditory Brain Stem Response (ABR) was experimentally developed, and ABR of subjects in general anesthesia were measured for the purpose of assessing the depth of anesthesia.

To make medical telemetry system more reliable in severe electromagnetic environment, we applied spread spectrum communication to ECG data transmission method. Spread spectrum communication system has shown superior performances to other systems, especially, in respect of anti-jamming, which allows it to share the frequency band with current telemetry systems. In this study, we show the characteristics of a spread spectrum transmitter when it is used in the same frequency band as a narrow-band transmitter. The result shows that the spread spectrum telemetry system can use the same frequency band permitted for medical telemetry system.