Pressure waveforms obtained by catheter manometer systems are often distorted by resonance of catheter and so on. Corrections by Fourier analysis, low pass filter and digital signal proccessing have been reported, but they have never been put to practical use.
We paid attention to the transfer function of catheter transducer systems and made a trial system that correct the distortion by natural observation method. This system increases the bandwidth in frequency domain and reduce the ringing in time domain. Advantages of this system are simple composition, a small number of adjusting points and real time performance without modifying the catheter or transducer.
In an animal experiment, we corrected by our trial system the output waveforms recorded by a conventional catheter manometer system and compared these corrected output waveforms with catheter-tip manometer waveforms which are relatively distortionless. As a result, we could obtain less distorted pressure waveforms in left-ventricle and aorta and distinctly confirm dicrotic notch in aortic pressure waveforms.

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In measuring body temperature, there are some errors caused by the difference of condition in which a thermometer is touched on the body surface and it takes some time to measure the temperature because of larger time constant of heat response of sensor and response time of body to set equilibrium thermal condition.
For the measurement of body temperature without such demerits, the characteristics of expiratory air temperature were examined. The condition in which the expiratory air temperature was measured stably was found. It needs some period of quiet breathing before the measurement and inspiration must be done by nose. It was found that the correlation coefficient between the expiratory air temperature and oral temperature is larger than the coefficient between axillary site temperature and oral temperature.
The new system was designed, which uses two thermisters to measure the expiratory air temperature with less than 0.1°C error in one second of the time constant.

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By making use of the correlations among the potentials measured at different sites on the body surface, the number of electrodes required to reproduce the body surface potential map (BSPM) can be reduced as Lux et al. pointed out. In their method, the potentials at some instant are estimated only from those measured at the same time. However, the omitted-lead potentials are correlated with those in the past and the future, so that the estimation error can be reduced by utilizing these correlations.
The omitted-lead potentials at time T are estimated from those measured at T, T±τ, T±2τ, and so on. The more terms being included, the more accurate the estimation, but the longer the computation time. In the present paper, four combinations, (T, T-τ), (T, T-τ, T-2τ), (T, T±τ) and (T, T±τ, T±2τ) are applied to the BSPM measured from 75 subjects with various heart diseases including normal ones, and the relations between the time-lag r and the estimation errors are investigated. For example, if the number of electrodes is 40 and the combination (T, T±τ, T±2τ) is ued, the estimation error becomes 81% of that estimated with the Lux method. The same error is obtained in the Lux method if 45-46 electrodes are used. In other words, the new method we propose here saves 5-6 electrodes. When the electrodes are restricted on the chest. our method is more effective and saves no less than 12 electrodes.

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Measuring principle of the single axis flexible electrogoniometer using specially designed strain gauges and the results of manufacturing by way of trial are described. Two pieces of strain gauges which length is extra large are plastered on the two opposite side of metal thin beam with uniform cross section, to form Wheatstone bridge circuit. The total amount of elongation of each strain gauge changes in proportion to the angle between both ends of the beam and does not depend on the deformation curves of the beam. So, the output voltage of the bridge circuit changes in proportion to the angle between both ends f the beam.
The weight of the measuring part is under 1g, width is 3mm, thickness is 0.1mm, and length is variable up to 90mm. It is very easy to flex, no convex part to the side direction, and can be used without taking off clothes. Moreover, it is easy to be attached on the joint without considering about alignment and is useful for measuring various kinds of human joints from large hip joint to small finger joint.
The characteristics of the electrogoniometer are largely improved compared with the one using electro conductive rubber. Non linearity and hysteresis are very small depending on the characteristics of the strain gauges. About the interference, as the aspect ratio (width/thickness) is very large, output does not be affected by the twisted angle of both ends between about -30 and +30 degrees. This shows that even if this goniometer is attached on the joint with twisted angle between these ranges, the correct data can be measured. This is the great advantage in case of the clinical use.

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The possibility of deep tissue temperature imaging with a magnetic resonance (MR) imager was studied in 20 mongrel dogs by systemic hyperthermia (group I: n=10) and hypothermia (group II: n=10) using an extracorporeal bypass method.
The coronary view of the brain was taken by Asahi Mark J (0.1 Tesla, spin warp method, T_r 1000ms, T_d 200ms) using a head coil (4 turns, bore diameter 120mm). The T₁s in the imaging of right and left white matter, grey matter, caudate nucleus, and thalamus were measured with rectal temperature in group I before heating, at 41°C and at 42°C and in group II before cooling, at 35°C, at 30°C and after rewarming.
In groups I and II, the T₁s at all sites except the white matter at 42°C did not change significantly at any rectal temperature. T₁ prolongation in white matter at 42°C may be due to edema probably because of topological biological reaction.
The present study suggests that deep tissue temperature imaging in vivo by T₁ using the MR imager may be impossible in spite of obvious evidence for temperature dependence of T₁ values in theoretical and in vitro studies already achieved.

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We have developed a system for measuring weak magnetic field caused by the conduction of action potentials in canine phrenic nerves. A micro-toroidal coil for picking up the magnetic field is designed to be openable for attaching to the nerve bundles. It is demonstrated that bursts of pulsatile change in the magnetic field could be detected with the system.

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A new method is presented here for detection of immunoreactions based on the measurement of intensity fluctuations of the depolarized light which is scattered in the forward direction by coated spheres.
Although the single scattered light by microspheres is polarized parallel to the incident light polarization, the double scattered light contains depolarized components. The normalized fractional variance from the double scattered field is inversely proportional to the square of the particle concentration, whereas that of the single scattered field is inversely proportional to the concentration. Therefore, the decrease of the concentration is sensitively detected by the measurement of the normalized fractional variance of the depolarized scattered light. In addition, undesirable single scattered light from microspheres is reduced by the present method.
The carrier particles used were latex spheres with diameter of 0.2μm. Latex spheres coated with antibody molecules aggregated after the addition of the antigen. The measured concentration of latex spheres was 4.5×10¹¹ particles/cm³, which was most convenient for obtaining double-scattered light. In these conditions, the fractional variance rapidly increased thereafter, and leveled off after 5-10 minutes. The antigen measured was α-fetoprotein (AFP) and immunoglobulin E (IgE).

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