1. The authors have studied the weighted likelihoodmethod with the aid of an orthogonal table. The weight of likelihood coeffiient was determined as a higher probability of correct classification and lower of malignant misclassification.
2. Four hundred and seventy two cases of acute appendicitis were used for this study. Using this method, an attempt at type-diagnosis of acute appendicitis is made.
3. “Algorithmn” is as follows : The likelihood coefficient is already known from data. Initially the value of weight of likelihood coefficient is assumed. Then the probability of correct classifiction and that of malignant misclassification are calculated by use of the L₂₇ (3¹³) orthogonal table according to the value of weight. Objective function is calculated from the two above-mentioned probabilities. Analysis of variance in objective function is performed. Subsequent value of weight is calculated as higher objective function is gained. These iterations are made until the peak value of objective function is obtained.
4. As the iteration is made, better objective function is obtained by use of the weighted likelihood coefficient as compared to the original likelihood coefficient.

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The mechanical behavior of the potassium arrested left ventricle is analysed by using a homogeneous and isotropic spherical shell model based on the large deformation theory. The strain energy function of the left ventricle is assumed as a function of two strain invariants. The material constants appearing in it are determined numerically so that the pressure-volume relation predicted by the equilibrium equuation agrees with the experiment data of the pressure-volume curve.
A uniaxial stress-strain relation for each ventricle is obtained from the strain energy function determined as above. This relation may serve as a standard of comparison of the mechanical behaviors of left ventricles having different pressure-volume relations and/or different sizes. The numerical results are plotted for eleven canine hearts in the state of control and three in the state of rigor mortis. There was a shift of the uniaxial stress-strain curve of the canine heart of rigor mortis towards right and bottom as compared with that of the control heart. It was thus found that the myocardium of rigor mortis was less compliant than the control heart.

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In order to develop the electrophrenic respirator, the voltage and the current threshold of the phrenic nerve of the dog and the impedance between electrodes are measured after implantation of nerve electrodes for a period of over a month. The thresholds rise in several postoperative days and reach steady levels. The mean values of the steady levels of the voltage and the current threshold are approximately 200 mV and 400μA respectively, and that of the impedance is about 400 Ω. A mercury-battery-operated implantable electrophrenic respirator with low power consumption was designed and assembled on the basis of these data. The power consumption of this device is about 300 μW so that the theoretical life of the battery is calculated roughly at 220 days. Continuous electrophrenic respiration is applied by the device for a few weeks with the results of slight increases in the thresholds and a slight decrease in the tidal volume.

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It has been pointed out that the hypertension is one of the physical factors which can cause a formation of atherosclerosis and accelerate atherogenesis. The mechanical constriction of vasa vasorum may occur due to abnormally high stresses in arterial walls caused by hypertension and the flow in the vasa vasorum may be impeded. Thus, it may be expected that the supply of nourishment to the arterial wall tissue will be impaired and this may lead to initiating structural degenerations. The purpose of the present paper is to investigate into the deformation of vasa vasorum embedded in an artery and the blood flow conditions in the vasa vasorum in order to examine whether or not above phenomena can occur. The deformation of the model vasa vasorum was analyzed and the relation between hydraulic resistance in arteries deformed by force and the configuration of the arterial cross-section was experimentally examined. The following conclusions were obtained from above analytic and experimental results.
Both arterioles and venules of the vasa vasorum underwent a finite deformation in the same way and the hydraulic resistance in those vessels increased at hypertensive levels of arterial pressure. The increasing rate of the hydraulic resistance, however, was not excessively high and depended on the configurations of the vasa vasorum at the physiological levels. It can be concluded, at present time, that the wall tissue degeneration may slightly be derived from the decrease of blood flow due to the large deformation of the vasa vasorum at hypertensive pressure and there may be little possibility that this wall tissue will develop into atherosclerosis

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Spike trains were recorded from single optic tract (OT) fibres in cats immobilized with local anesthesia. Markov properties of nonstationary spike trains were investigated every 20 msec from 1.0 sec before to 1. 5 sec after the light spot presentation. A statistic which evaluates the order and the values of Markov properties was developed and employed in nonstationary spike trains.
In X-type OT responses, the order of Markov properties was the 1-st ; and the value increased for about 370 msec after the light was on, and gradually and continuingly increased for about 510 msec at the congest before the light was off.
On the other hand, in Y-type OT responses, the order of Markov properties was the 1-st ;and the value increased for about 120 msec after the light was on, increased gradually for about 360 msec at the congest, and decreased to the control level for about 1.0 sec.

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This paper describes a method of evaluating α excitability using muscleforce-frequency curve (F-f curve).
The F-f curve is measured as the relation between the frequency and torque when the human abductor digiti quinti muscle is driven by percutaneous stimuli. Here, the frequency can be varied continuously and linearly and the F-f curve recorded automatically.
The α excitability is evaluated with the frequency where the muscleforce on the F-f curve reaches one-half of its maximum value. These evaluated values show fairly close correlation with the results obtained by the physical methods.
Furthermore, the behavior of the neuromuscular control system can be explained with a model under the assumption that the muscle and receptors are excited synchronously with the stimuli.

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The QRS-T wave was simulated by a mathematical model of electrical heart activity, and quantitative relationship was investigated between the T wave polarity and the ventricular gradient. A rectangular solid model was constructed for this study, which was composed of the working myocardium and the excitation conduction system uniformly distributed on the endocardial surface. The propagations of both depolarization and repolarization processes can be determined mathematically in this model for a given ventricular gradient and values of conduction velocities of the conduction system and the working myocardium. The electrical potentials at given points in a homogenous infinite volume conductor were calculated as the sum of the time-varying dipoles in each 1 mm cubic block (60, 000 blocks in total), which was calculated on the basis of transmembrane action potentials.
The present model reproduced the characteristic patterns of the QRS complex and T wave seen in clinical electrocardiograms, and disclosed that the ventricular gradient more than 20 ms/cm as the difference of the duration of action potentials between the endocardial and epicardial surfaces can produce the positive-polarity T wave in the left precordial leads, although the T wave polarity is much influenced by the conduction velocities of the myocardium and the conduction system as well as the ventricular gradient.

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Water hammer may occur in a closed conduit when there is a rapid retardation of the flow with the closure of a valve. In an aorta with an artificial aortic valve, substantial regurgitation of the blood flow occurs just before the valve is closed, and when the valve is closed the regurgitating flow is stopped suddenly. This causes a pulse of high pressure to be propagated along the aorta. These water hammer pulses were measured in the aorta of a dog with an artificial aortic valve. In the vicinity of thh valve, the peak of the water hammer pressure exceeded the peak systolic pressure. Water hammer pulses were measured also in a forty-four-year-old male after valve replacement for annulo-aortic ectasia.

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Mechanoreceptor cells produce a single or sustained impulse responding sensitively to certain kinds of mechanical stimuli. To understand their mechanisms and to apply them to mechanoelectric device, a model system consisting of a synthetic lipid, i. e., dioleylphosphate (DOPH), absorbed in a Millipore filter and an electrolyte solution was studied applying constant pressure stimuli. It is already dy known that the system exhibits a sustained variation of membrane potential responding to electric stimulus. However, a sustained variation with a pressure stimulus has not been reported yet in this system. Our studies have revealed that, when absorbed quantity of DOPH in the filter is between 4.9 and 7.6 mg/cm², the system produces a sustained variation of membrane potential during application of constant pressure stimulus. The frequency of the oscillation also was proportional to the change in pressure within a limited range. The phenomenon was considered to come from the conformational change of DOPH molecules.

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A continuous recording of the changes in the right atrial diameter by ultrasonic method is a useful tool for a study of the mechanism of venous return including dynamic performances of right atrium. The technique of sonomicrometer for measuring right atrial dimension was reported by G. Recordati using H. F. Stegal's method for the time in the cat. His method meets with a difficulty of keeping accuracy and stability and, besides, it needs the complicated adjustment to measure fine change within a little distance such as the dynamic change of the right atrial diameter. These difficulties have been overcome by the method which converted the transit time of ultrasound to the phase differences of square wave due to the analog conversion with phase comparator.
With this technique of sonomicrometry, the dynamic change of right atrial diameter could be accurately measured and continuously recorded, so that the active contraction and passive filling phase of right atrium, which is an important performance of functional behavior of right atrium in the mechanism of venous return, was clearly discerned, and also, the effect of dopamine on these, phase was markedly recognized.

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