医用電子と生体工学
Online ISSN : 2185-5498
Print ISSN : 0021-3292
ISSN-L : 0021-3292
15 巻, 6 号
選択された号の論文の11件中1~11を表示しています
  • 古川 友三
    1977 年 15 巻 6 号 p. 377-382
    発行日: 1977/10/30
    公開日: 2011/03/09
    ジャーナル フリー
  • 福島 重広, 宇都宮 俊二, 相馬 敬司
    1977 年 15 巻 6 号 p. 383-388
    発行日: 1977/10/30
    公開日: 2011/03/09
    ジャーナル フリー
    A method for obtaining the contour of a stomach from radiograms is presented. The method forms a part of a fully automated interpretation system designed for the diagnosis of a large number of radiograms of the stomach obtained, for example, in mass surveys. First, major figures are extracted by a dynamic threshold method and finally the image of the stomach only is obtained by labeling and extraction of the figure with the largest area. The contour is then obtained by a boundary following algorithm. Another program was written to obtain the medial axis of the stomach and to eliminate the image of the intestine using the methods of skeletoning, distance transformation and inverse distance transformation. The output may be used for the recognition of global characteristics and as a guideline for obtaining the accurate contour to be used in methods based on the analysis of contour irregularities.
  • 今泉 敏, 比企 静雄
    1977 年 15 巻 6 号 p. 389-396
    発行日: 1977/10/30
    公開日: 2011/03/09
    ジャーナル フリー
    Merits of a pulse counting method for extraction of the motor command, or the control signal of muscle contraction, from electromyogram (hereafter EMG) recorded with a pair of hooked-wire electrodes are discussed. First, based on the consideration of the mechanisms of the transmission of the motor command and the observation of EMG, it is discussed that the motor command of speech gesture can be extracted more accurately by the pulse counting method, that is, by detecting as, many neural impulses as possible, and extracting the analog time pattern of change in the pulse density, rather than by the rectifying-smoothing method which has been used in experimental phonetics. Then the optimum condition of the pulse counting method is examined and it is compared quantitatively with the rectifying-smoothing method by computer simulation. The material used here is the EMG of the thyrohyoid muscle recorded during the utterances of a nonsense mora sequence with four accentuation types. The accuracy of extraction of the motor command of accentuation type for each utterance is evaluated by an average correlation ratio which indicates both degree of similarity in an accentuation type and degree of dissimilarity among accentuation types. As the results, it is shown, in the pulse counting method with some modification for reducing the miscounting, that the optimum threshold for the detection of pulse train lies at 1/40 of the maximum pulse amplitude, and the optimum width of time window for extraction of analog time pattern of change in the pulse density is about 170 ms which is. somewhat shorter than the duration of one mora. Then it is also shown that the modified pulse counting method with the optimum threshold and width of time window gives better results compared with the rectifying-smoothing method. Finally, it is demonstrated that the modified pulse counting method can be carried out in real time by an electronic circuit.
  • 田村 富士夫, 寺岡 甲太
    1977 年 15 巻 6 号 p. 397-402
    発行日: 1977/10/30
    公開日: 2011/03/09
    ジャーナル フリー
    This paper describes a reexamination of the relationship between the electrode area and the threshold current through the use of various types of electrodes (endocardial, myocardial and epicardial disc electrodes), for designing a low-power stimulation electrode of cardiac pacemakers. Results are as follows.
    1. As the electrode area is made smaller and smaller, threshold current becomes less and less until a point is reached where the value becomes more or less constant.
    2. As the area of the electrode is reduced, the ratio of incremental increase of the threshold current (increased threshold current due to inactive layer interposed under the electrode/threshold current with direct contact to ventricular wall) increases but this also stabilizes itself to a constant value after a certain point is reached. This fact corresponds to the results obtained through long-term implantations of the endocardial electrodes.
    3. On the other hand, the resistance of the electrode is inversely proportional approximately to the square root of its area. From these results, we deduced that the design and fabrication of an electrode with minimal threshold energy and highest safety margin of the stimulation current (stimulation current/threshold current) is entirely feasible, if the electrode area is around 10 mm2.
  • 佐藤 正明, 林 紘三郎, 新見 英幸, 半田 肇, 森竹 浩三, 奥村 厚
    1977 年 15 巻 6 号 p. 403-409
    発行日: 1977/10/30
    公開日: 2011/03/09
    ジャーナル フリー
    The mechanical property of arterial walls is one of the most important factors which affect the blood circulation. Most studies related to dynamics of arterial walls to date have consists of analyzing the response in the circumferential direction of a tubular vessel rather than in the axial direction. Histological findings, however, indicate that the arterial wall has anisotropic mechanical properties. It is necessary, therefore, to analyze the mechanical properties of arterial walls in two directions, i. e. the axial and the circumferential directions. In the present study, the axial deformation behavior of arterial walls has been investigated by the tensile test.
    Abdominal aortas, common carotid arteries and femoral arteries obtained from 5 mongrel dogs were stretched in the axial direction, keeping the internal pressure at various levels. Results obtained are :
    1) The deformation-rate dependency of mechanical behavior was not observed in the range of 0.1 to 10.0 mm/sec.
    2) Mechanical properties of arteries in the axial direction were dependent on the internal pressure applied. This pressure dependency was largest in the abdominal aorta. The maximum extensions were not affected by the internal pressure level.
    3) The internal and the external radii, and the wall thickness of arterial walls decreased gradually with increasing axial tension in the lower stress range. In the higher stress stage, however, there were rapid decrease in these radii although the wall thickness remained unchanged.
    4) The anisotropic mechanical behavior was observed clearly. In the lower deformation range, arterial walls were more extensible in the circumferential direction than in the axial direction, but vice versa in the higher deformation range.
    5) Mechanical properties of arterial walls in the axial direction were expressed by the constitutive equations which we proposed in a previous paper (Jap. Jnl. Med. Electr. and Biol. Eng., Vol. 13, pp. 293-298 (1975)).
  • 静電容量変化を利用したプレチスモグラフィ
    川上 憲司, 渡辺 瞭, 池田 研二, 大島 正光
    1977 年 15 巻 6 号 p. 410-415
    発行日: 1977/10/30
    公開日: 2011/03/09
    ジャーナル フリー
    In a previous paper, we reported the principle and electrical characteristics of capacitople-thysmography which is a method to detect thoracic plethysmograms by detecting capacitance change between insulated electrodes.
    This paper aims at confirming by animal experiments that this method detects the mechanical movement of the heart and haemodynamics in the heart or lung.
    An oscillator (100 MHz) is suspended a few centimeters above the thoracic cage (non-contact CPG) or set up on the thoracic wall (contact CPG) on an anesthetized dog.
    Non-contact CPG waves detect the resistive component of intrathoracic tissue. The detecting depth of contact CPG depends on the distance between electrodes. When the distance between electrodes is relatively large (10 cm), CPG waves reflect blood volume change in the heart or lung. At a relatively small distance between electrodes (4 cm), CPG is associated with the anterior wall movement of the heart.
  • 菊地 真
    1977 年 15 巻 6 号 p. 416-422
    発行日: 1977/10/30
    公開日: 2011/03/09
    ジャーナル フリー
    It has been reported that the impulse propagation in the smooth muscle is greatly affected by the temporal and spatial characteristics of a single muscle cell. Although there have been many papers which investigated the characteristics of a single cell by means of microelectrode technique, the impulse propagation along the network of cellular structure in the smooth muscle of the bladder has not been quantitatively analysed. In the present study, the author presents the mathematical method to analyse the random construction of the cellular network using the analog neuron-like elements model proposed by Amari in 1972. The model has been slightly modified so as to insert an external input and to be stimulated by the repeative external pulse. The simultaneous differential equations expressing the “macroscopic state” are introduced, which express the relation between dU/dt and dV/dt, where : U is the macroscopic internal state of the smooth muscle cells, V : the variance of U and t : time. The simulation study using a digital computer has been carried out on the model in order to obtain the relations between the macroscopic output (the isometric intravesical pressure of the bladder) and the parameters such as the input pulse frequency, pulse width and pulse amplitude. From the analysis of the former two relations, it was demonstrated that there are convex characteristics, while there is a sigmoid characteristic in the third relation. The author has suggested that the reason for decrease in the macroscopic output in the high frequency range may be caused by the increase in the variance V rather than the increase in U.
    In 10 dogs, the author has measured the isometrical intravesical pressure of the bladder by stimulating it with repeative electrical pulses. The results obtained from the animal are the same as those obtained from the model.
  • 保坂 栄弘
    1977 年 15 巻 6 号 p. 423-426
    発行日: 1977/10/30
    公開日: 2011/03/09
    ジャーナル フリー
    This paper presents and interprets two types of magnetocardiograms (MCG's) of normal heart subjects, obtained by measuring magnetic field component normal to the skin, for the purpose of assessing the features of various methods of MCG detection and display. The MCG's were recorded with a superconducting magnetometer in a shielded room at the MIT.
    The results are as follows (1) The MCG's, measured for the normal component of magnetic field at the finer grid points on the chest with close proximity to the skin, indicate some interesting information concerning the heart generator, especially in the region of the peak of QRS. (2) The MCG's, measured for the second-derivative of the normal component, indicate some interesting information concerning the activation of epicardium and the special configurations. of heart generator, not apparent from the MCG's in the direct normal component. (3) In order to estimate the configuration of heart generator, it is effective to use the MCG's for direct normal component together with those for second-derivative.
  • 磯 泰行, 古賀 正明
    1977 年 15 巻 6 号 p. 427-430
    発行日: 1977/10/30
    公開日: 2011/03/09
    ジャーナル フリー
    When we want to use digital filters to process random pulse train inputs, we encounter some difficulty since the instants of the random input pulses do not usually coincide with the sampling instants of the filters. But we can avoid the difficulty, if we assume that the responses of the digital filter to an arbitrarily located input pulse are equal to the sampled values of the responses of the analog filter, which is derived from the digital filter by impulse invariant transformation, to the same pulse. Using this relation, we can realize a kind of fast recursive filters as follows.
    1. Design a usual recursive filter with required response characteristics. The parallel form realization is desirable for several reasons.
    2. For each input pulse, compute initial values of this filter using the impulse invariant analog filter.
    3. Compute further responses recursively, as usual, by solving the difference equations of the filter.
    In most practical cases, the above filter is several times as fast as the direct convolution type filter.
  • 高山 一成
    1977 年 15 巻 6 号 p. 431-432
    発行日: 1977/10/30
    公開日: 2011/03/09
    ジャーナル フリー
  • 1977 年 15 巻 6 号 p. 433
    発行日: 1977年
    公開日: 2011/03/09
    ジャーナル フリー
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