A new formula describing the flow impedance of a cylindrical tube was derived from a step response of unsteadystate laminar flow. In spite of a simple form of this equation, it can describe the exactly same frequency response of the flow impedance as that obtained from Womersley's solution. This formula also directly gives the equivalent electrical circuit which is the simple parallel connection of series branches consisting of resistance (R) and inductance (L). The equations for detemining these frequency-dependent R and L components were derived and applied to a frequency response analysis of catheter-manometer system. The discrepancy between experimental and theoretical results, found in a conventional model, was greatly reduced by employing these equations.

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Ankle joint stiffness was measured while visual stimulation was applied to quietly standing ten healthy subjects using head-mounted display (HMD). The presented image consists of eight horizontal stripes moving up and down in 8 and 32 seconds cycle, with and without a fixed (non-moving) point display. The measured ankle joint stiffness during the visual stimulation with a fixed point showed the intermediate value between the eyes-open and the eyes-closed conditions, while the visual stimulation without a fixed point induced the larger stiffness as expected. The less stiffness due to the fixed point than eyes-closed condition was confirmed in other nine healthy subjects with the same visual stimulation protocol but at 4, 8, 16 and 32 seconds cycle. The trajectory length of the center-of-pressure was also measured on the same subjects. The better postural stability than eyes-closed condition was confirmed in the both methods. It was hypothesized that the position error between the actual gaze point and the presented fixed point was induced by vestibular reflex, and the subject detected the postural information from that error. The head position and electro-oculogram was measured in five subjects wearing HMD and vestibular reflex was observed. It was revealed that gazing a point improves the postural stability presumably by contribution of vestibular reflex, even in a case gazing point does not provide position information such as HMD environment.

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In order to construct a first screening system for the home care, we investigated assessment of brain function disorder. In this study, we constructed a model for assessment of aphasia from electroencephalogram (EEG) using artificial neural networks (ANN). EEG data of the following patients were collected; the patient of total aphasia who is difficult to understand the speech and the patient of motor aphasia (Broca aphasia) who feels pain or makes some grammatical mistakes when he speaks anything while he can understand the speech. At first, power spectrum of EEG was extracted by the fast Fourier transform (FFT). Power spectrum was separated into 9 regions, corresponding to the characterized waves, and relative power values were calculated from them. The regions with 4.0 to 5.9, 6.0 to 7.9 and 8.0 to 12.9Hz were selected as the frequency band of θ₁, θ₂, and α waves, respectively. Assessment of linguistic ability was carried out by Western aphasia battery (WAB). The relative power values were input into each ANN model for estimation of aphasia quotient (AQ) score or score on spontaneous speech from WAB. The average error of ANN model for AQ score was 7.02 points out of 100. It was found that the model can estimate the AQ value at high accuracy. Another ANN model to estimate the score on spontaneous speech was also constructed. The average error of this model with actual spontaneous speech score was 0.27 points out of 20. Predicted score of patient with motor aphasia coincided well with the actual score. In conclusion these models can quantify the severity of aphasia from EEG.

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[Summary] Measurement of 3D deformation is indispensable to orthopedic image diagnoses. But so far it is difficult to quantify the deformation between two images obtained at different opportunities accurately, because correspondence between them is obscure. In this study we developed a new method to match such images by elastic matching and quantify the deformity. [Method] We implemented an elastic matching method, which measures the matching energy measure E as sum of voxel similarity measure E_m and elastic strain energy R. We defined E_m as root mean square of the differences of voxel value between two images. After matching, displacement vectors for all voxels in pre-injury image are obtained and the difference in two of them is the relative change in location of the two points. [Tests] We used MRI of ACL deficient knee case (suspected). Firstly, as an accuracy test, arbitrarily deformed MRI scans was restored by elastic matching and restoration errors in lengths and angles were measured. The results showed that the restoration errors in length were less than the size of a voxel. The accuracy of this method was sufficient. Secondly, as a clinical test, we measured the changes in coordinates of ACL bony insertions and length of ACL from MRI scans of the same case obtained before and after re-injury. The measured coordinates of tibial insertion were less accurate by usual manual method than by our method. The measured lengths were almost equal. [Conclusion] We developed a new method to quantify 3D orthopedic deformity by elastic matching. Non-linear biological deformities can be quantified three-dimensionally by this method.

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Motor disabled patients usually use their residual motor functions to control welfare apparatus. It is desired to develop the control command input system which can be applied to the patients with various paralysis condition. In this paper, the command input system which consists of a 3D position measuring device and an artificial neural network (ANN) for detecting control commands from residual motor functions of the patients was studied. The ANN detects a specific movement by the patients to decide a control command. The control command is selected by the change of 3D position which is caused by the same part movement as the specific movement. Considering the clinical application of the command input system with C4 quadriplegic patients, recognition of the nodding by the ANN was studied at first. Then, the command input system which includes the nodding detection and command selection by head movements was examined in character input with four normal subjects and a C5-6 quadriplegic patient. In application of the command input system to a C5-6 quadriplegic patient who has parts of residual motor functions of upper extremities, change of hand position on a desk by rapid elbow flexion were recognized by the ANN to decide a control command. The performance of the command input system which uses the rapid elbow flexion for the decision and the change of hand position on the desk for the command selection was examined through character input experiments. From those examinations, the command input system was found to be applicable to different parts of residual motor functions providing good performance of system operation. The experimental results also suggested that the control command source have to be selected appropriately on a patient. Therefore, this system can be useful for motor disabled patients with different paralysis condition.

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The effects of flow on the changes of electrical resistivity of blood were experimentally and theoretically discussed. Studies indicated that most erythrocytes deform and orient themselves in the flow direction when blood flows. Such oriented blood shows anisotropic physical properties. Anisotropic electrical resistivity of flowing blood was measured in three rectangular directions with a measurement cell of coaxial cylindrical type. A fresh whole blood, an erythrocytes suspension in saline and a hardened erythrocytes suspension in saline were used as samples. From these experimental results, the orientation and the deformation of erythrocytes were discussed. For whole blood 45% in hematocrit, the anisotropy increased with the increase of shear rate and approached a saturation state, and the saturation values of resistivity were about 20% higher than the initial value in the radial direction, and about 15% lower than the initial value in the circumferential and axial directions respectively. The erythrocyte suspension in saline showed anisotropic resistivity even at rest. The resistivity of hardened blood did not depend on the shear rate of flow. The orientation ratio and the deformation were calculated with a simplified spheroidal model of an erythrocyte. The result for whole blood showed that both the fractions of erythrocytes with their short axis parallel to each direction and the equivalent axis ratio for a simplified spheroidal model changed with the shear rate of flow. However calculated results of hardened blood coincided well with the Jefferys' theory. These results suggested that not only the orientation but also the deformation of erythrocytes are very important for the analysis of physical properties of flowing blood.

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Existence of spicules around a mass is one of the important signs which characterize malignant tumors. In this study, we developed a new automated method for detecting spicules for each mass on mammograms and determined a spicule feature value. Digital mammograms were obtained with a laser film scanner with 0.1-mm sampling distance and 10-bit density resolution. After the smallest rectangular region containing the mass area was cut off and high-frequency components were enhanced by using an unsharp-mask filter, the magnitude components of density gradient vectors were calculated within the segmented mass area. The detection was performed by using a “multistage pendulum filter” which was newly developed. Then, the spicule feature value, which indicates the degree of “spicule presence” around the mass, was calculated from the detected spicules. The multistage pendulum filter was evaluated with 71 Japanese women's digitized mammograms, and it was able to show the most of the spicules that a radiologist pointed; the sensitivity of 88.5% and specificity of 80.0% were obtained, which demonstrates the effectiveness of our proposed method.

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We constructed a model for assessment of senile dementia of Alzheimer type (SDAT) from electroencephalogram (EEG) using artificial neural networks (ANN). EEG data of the SDAT patients and the non SDAT patients were collected. At first, power spectrum of EEG was extracted by the fast Fourier transform (FFT). The power spectrum was separated into 9 regions, corresponding to the characterized waves, and relative power values were calculated from them. The regions with 4.0-6.0, 6.0-8.0 and 8.0-13.0Hz were assigned as the frequency bands of θ₁, θ₂, and α waves, respectively. The average power value in all electrode positions of the head was also calculated. The severity of SDAT was assessed by Hasegawa's dementia rating scale (HDS-R). The relative power values and the average power value were input into each ANN model for the distinction of SDAT patients from non SDAT patients and estimation of HDS-R score of the patients. Using the acquired ANN model, SDAT patients are distinguished from non SDAT patients. The average error of ANN model for HDS-R score was 2.64 points out of 30. In conclusion these models are the useful tools in order to distinguish SDAT patients from non SDAT patients and quantify the severity of SDAT from EEG.

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