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This work reports on a method of analysis and statistical correlation of electromyographic and cephalometric parameters. Has been employed a computer as oscilloscop with digital memory.
Before hatching, chick embryos show a high incidence of inwardly rectifying potassium channels and calcium-activated potassium channels in the apical membrane of their lens epithelium. Subsequent to hatching, these channel types disappear while, at about the same time, a new calcium insensitive maxi potassium channel appears. This new channel shows several properties in common with the calcium-activated maxi potassium channels but is different in its conductive and gating properties.
The use of digital techniques for the display of electromyographic signals often introduces grave errors in the visualization of the high frequency signal components. The causes for this can be quantitatively deduced from the technical principles of the systems. In the digital storage oscilloscope, the accuracy of reproduction is determined by the sampling rate and the memory capacity. In addition, there may be a considerable loss of quality in the visual display of systems using computer graphics despite accurate signal acquisition. Based on the quantitative analysis recommendations as to the technical equipment and use of digital neurophysiological systems are given.
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We present an experimental frequency analysis of a neurological control system, the accommodation system, using single sinusoids. Also, by means of continual experimental calibration full coverage of one subject's dynamic range, we demonstrate an AC nonlinearity saturation, which probably lies in the motor-response portion of the system; in contrast to the switching-mode nonlinearity, which probably lies in the sensory-processing portion. We offer our findings as a basis for further models. In addition, our results can be compared with studies using multiple sinusoids and transients to document how the different aspects of the accommodation system are realized given their different input conditions.
A commercial tracking system has been adapted within the University of Melbourne, which is designed to track the movement of infra-red light emitting diodes (LEDs). The movement of the diodes was recorded by photosensimetric recording devices, and sent to a data recorder, then to a differential amplifier, and the signal stored on magnetic tape, or viewed on a cathode ray oscilloscope, or plotted on a chart plotter or an X-Y plotter. The equipment was used to track the movement of LEDs, which were secured to a lower arch face bow, which was in turn secured to the teeth via a universal joint, and an acrylic clutch. A method was established in a preliminary study, enabling recording of condylar movements in the sagittal plane, and results were presented for four subjects. Subsequently, condylar movements and joint sounds were recorded concurrently for two of these four subjects.
A recently developed computer program is capable of rapidly (less than 5 minutes) constructing a series of potential-distribution maps (PDMs) for every msec of a 4-second window of ventricular tachycardia (VT). This study was performed to assess the ability of a series of PDMs to localize the site of earliest activation of VT originating in the interventricular septum. In 12 dogs, 13 morphologies of VT were initiated with programmed electrical stimulation 3-6 days after anterior septal coronary artery infarction. VT was mapped with endocardial and epicardial unipolar electrodes with a multipoint, computer-assisted mapping system. PDMs were compared with activation-time maps, and the former correctly identified the site of earliest activation of all 13 VT morphologies. When PDMs were viewed in sequence on a computer monitor, the site of earliest activation was signaled by abrupt development of a negative potential of less than -3.0 mV. The initial negative point subsequently expanded, and the spread of this negative-potential field correlated with activation sequence. PDMs provide an accurate, unambiguous, rapid means of analyzing large numbers of electrograms acquired with multipoint, computer-assisted mapping systems.
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The authors discuss basic problems of analogue - digital transmission focused on practical questions with regard to the application of medical technique in combination with a computer. They discuss the different parts of the digital-measurement chain, different methods of signal transmission and finally also practical applications.
By means of dynamic thermovision method, distant reactions of the cerebral cortex were studied in white rats appearing under local chemical action (2% KCl). Besides the previously described temperature wave SD (T-wave), in these conditions in the contralateral hemisphere local areas of warming up (0.2-0.3 degrees) were observed symmetrical with the place of stimulation. Under local chemical action, latent foci of excitation were revealed on dynamic thermal maps of the brain surface in the areas of the same or contralateral hemisphere, distant from the places of stimulation. During creation of two K+ foci a change was observed of place of T-wave appearance and of the usual order of its propagation over the cortex and also the formation of a focus of prolonged temperature fluctuations in the place of two T-waves meeting. On the basis of the obtained data a number of questions is discussed on the forms and mechanisms of distant effects in the CNS.
A small-size and low-cost microcomputer using an Intel 8080 micro-processer is employed to provide real-time data collection and reduction of a three-channel electronic-readout thrombelastograph (TEG). Computed values of significant clotting parameters are obtained instantly allowing for rapid analysis and monitoring of many patients. Computer hardware was designed to optimize signal sampling rates, processing time and storage.
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Temporal sound processing is likely to depend upon a delay line at a low level in the auditory pathways. We searched for such a delay line in the medial superior olivary nucleus of anesthetized cats. A remarkably pure sinusoidal neurophonic field potential could be recorded in the center of the MSO which was localized electrophysiologically as the point of the field potential polarity reversal and histologically by microinjection WGA-HRP through the recording microelectrode. Fourier analysis of the neurophonic potentials revealed increasing degradation by distortion products with distance from the MSO center. Neurophonic tuning curves indicated a similar frequency selectivity for individual recording sites as predicted by cochlear filter functions. Cross correlation of neurophonics recorded at different positions along the medio-lateral axis demonstrated the presence of a delay line, extending to over 0.6 ms. It is concluded that delay lines required for directional hearing and complex tone identification exist in the MSO.
Resonance artifacts introduced by the catheter-manometer system are removed from the direct radial artery pressure using a three-step algorithm. First, the fast-flush method is used to identify the natural frequency and damping coefficient of the monitoring system by digitizing and analyzing the pressure transient created by the flush. Second, resistor, capacitor, and inductor values are found for an RLC second-order model of the catheter-manometer system in use. Third, the algorithm predicts the undistorted radial artery pressure, removing the resonance artifacts by inverse-filtering the digitized monitored pressure waveform using the RLC circuit derived previously. The algorithm was implemented using a personal computer, but it could also be used without the computer by incorporating an analog-to-digital convertor and a microprocessor in the hemodynamic monitor.
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A Zenith Z-100 PC system was used to control an automated feeding system for determining the angular limits at which a monkey would respond to a food stimulus. Raisins secured to the end of a rotating arm by means of vacuum pressure were delivered to the monkey alternately from clockwise and counterclockwise directions at a fixed radius. The point at which the monkey took a raisin from the end of the arm was determined by an increase in negative pressure. The arm position was measured by using a potentiometer mounted in the arm gear train. The computer system controlled the experiment as well as the on-line recording and plotting of data.