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Proceedings of the IRE

Issue 11 • Date Nov. 1959

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Displaying Results 1 - 25 of 37
  • Poles and Zeros

    Page(s): 1813
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    Freely Available from IEEE
  • Lloyd V. Berkner, Director, 1959

    Page(s): 1814
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    Freely Available from IEEE
  • Guest Editorial

    Page(s): 1815
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    Freely Available from IEEE
  • An Analog Computer to Simulate Systems of Coupled Bimolecular Reactions

    Page(s): 1816 - 1820
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    An analog computer has been constructed to simulate, as nearly as possible, the flux of material in systems of coupled chemical reactions. Concentrations of various reactants, intermediates, and products are represented by the potentials at the outputs of electronic integrators. Rates of turnover of materials are represented by charges flowing to and from the integrators. The charges are caused to circulate by means of a "pump" mechanism that transfers charge at a rate proportional to the triple product of three voltages, two of which are derived from integrators and represent the concentrations of reactants. The third represents a rate constant. One voltage controls the frequency of an oscillator, the second, the duration of a triangular waveform, which is triggered by the oscillator, and the third, its rate of rise. By suitable interconnection of a number of integrators and pumps, a wide variety of reaction schemes can be simulated. View full abstract»

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  • Electron Transfer in Biological Systems

    Page(s): 1821 - 1840
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    The direct approach to a study of the dynamics of the essential intermediates in life processes is afforded by sensitive optical techniques that accurately measure and record the absorbancy of the iron proteins (cytochromes) in living cells, tissues, and particles derived therefrom. This paper outlines the nature of physical phenomena measurable in the biological systems and emphasizes current thinking on the nature of electron transfer between the proteins which involves oxidation and reduction of their iron-containing active centers with the simultaneous conservation of energy required for driving essential biological processes. The methods for these measurements are reviewed and spectrophotometric techniques at room and liquid nitrogen temperatures, and new developments such as microspectrophotometry of the cytochromes in portions of the living cell are emphasized. Data evaluation and representation of electron transfer processes and metabolic control sequences by analog and digital computers are described and particular reference is made to the operation of metabolic controls in ascites tumor cells. View full abstract»

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  • Correction

    Page(s): 1840
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  • Alternating Current Spectroscopy of Biological Substances

    Page(s): 1841 - 1855
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    The electrical properties of live matter are analyzed. The article first summarizes general principles which pertain to the frequency dependence of the electrical properties of any type of matter. It then states the particular mechanism which, at various parts of the total frequency spectrum, are predominantly responsible for observed data. They include time-dependent interface polarization, accumulation of charges due to inhomogeneous structure and orientation of polar molecules. The electrical properties of water and electrolytes, of protein suspensions, of subcellular and cellular structures are outlined in terms of previously mentioned mechanism. This, in turn, permits synthesis of the experimentally observed dielectric parameters of tissues. The treatment encompasses the total range of frequencies, from 1 cps to 100,000 mc. The article concludes with a chapter which outlines the application of the data and pertinent impedance techniques to a variety of basic and applied problems in biology and medicine. View full abstract»

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  • Comments on Microelectrodes

    Page(s): 1856 - 1862
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    Metal-filled microelectrodes are best for high-frequency work; fluid-filled ones are best for low frequencies and dc. Both have advantages and drawbacks. This paper gives the results of experience with both sorts of probe. Practical hints and recipes are included because these seldom appear in detail. View full abstract»

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  • Some Functions of Nerve Cells in Terms of an Equivalent Network

    Page(s): 1862 - 1869
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    A distributed parameter equivalent network of a nerve cell is developed. The network is based upon the electrical constants of nervous tissue. Inserted in the network are electrically and chemically activated generators. Some experimental evidence is given for the properties of the network and the generators, as well as for the location of the generators in the network. The function of the neurons in the nervous system is discussed in terms of this network. View full abstract»

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  • Electronic Control of Some Active Bioelectric Membranes

    Page(s): 1869 - 1880
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    Special purpose real-time analog computers are used to measure and control nerve membrane potential or current in a squid axon or a single frog node. Under current control, the membrane potential has a region of discontinuity and an "action potential" rather similar to that observed in normal impulse propagation. With potential control, the current pattern is a continuous function of the potential, and a negative resistance is found in the region of potential discontinuity for the current-controlled membrane. The membrane's electrical characteristics may therefore be compared with some two-terminal transistor switching circuits. View full abstract»

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  • Measurement of Mechanical Properties of Muscle under Servo Control

    Page(s): 1880 - 1888
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    Accurate measurement and analysis of the mechanical events in active muscle requires the use of high-speed equipment. A hydraulic servo-valve, controlled by analog units (integrators, adders, inverters), can be used to control the speed of shortening of muscle at rates as high as 1 mm per millisecond. The apparatus can be used for isometric, isotonic, and controlled release experiments. Both release and stretch, at high or low speeds, can be produced during a single contraction cycle. Force is measured by an unbonded strain gauge of high natural frequency and low compliance. To maintain constant force on the muscle, a signal proportional to measured force is fed into an error detector, whose output controls the servovalve piston. The instrumentation described can provide the necessary and sufficient information to specify completely both transient and steady-state mechanical properties of muscle. View full abstract»

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  • Scanning Microscopy in Medicine and Biology

    Page(s): 1889 - 1894
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    Scanning microscopy provides the means for extending the range of usefulness of the light microscope in several directions. In addition to the convenience of viewing a large bright image on the television type monitor, it can also enhance the contrast of faintly visible specimens and can extend the convenience of direct observation into the infrared and ultraviolet. By electrical processing of the video signal, a great deal of quantitative information can be extracted. This method has been used to determine the number, size, and size distribution of particles in a field and to quantitate absorption of biological materials for visible and ultraviolet light. View full abstract»

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  • Instrumentation for Automatically Prescreening Cytological Smears

    Page(s): 1895 - 1900
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    Mass-screening application of the cytological smear for the detection of cervical cancer has been limited by a lack of technicians to screen the smears. By using an instrument to identify automatically those smears which are clearly negative, the effectiveness of the technician could be greatly increased. A quantitative analysis of a large number of smears showed that positive smears usually had a small number of cells with abnormally large and intensely stained nuclei that did not appear on negative smears. On the basis of this analysis, an experimental instrument-called the Cytoanalyzer-has been constructed. The Cytoanalyzer scans a smear, measures the size and light absorption of approximately 10,000 cells on the smear, classifies each cell normal or abnormal according to its nucleus size and absorption, and totals the number of cells falling into each classification. The smear is then classified normal or abnormal depending on the fraction of cells having abnormal characteristics. Preliminary tests with the Cytoanalyzer have been very promising. In a test of approximately 1000 smears, 65 per cent of the premenopause smears and 35 per cent of the postmenopause smears were properly identified. Plans are now underway to make a more thorough test of the screening capabilities of the instrument. If the test is successful, development of a clinical instrument will be started. View full abstract»

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  • A Magnetic Flowmeter for Recording Cardiac Output

    Page(s): 1901 - 1912
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    The cardiac output flow pulse (less coronary flow) can be recorded with a magnetic flowmeter applied to the unopened ascending aorta, provided: 1) the extremely large EKG potentials in this region are rejected, 2) the flowmeter is phase-sensitive, and 3) the over-all instrument response is uniform from zero to 100 cps. These requirements are fulfilled by the instrument described through the use of the square-wave method recently introduced by A. B. Denison, and by using a high switching frequency (480 cps), an input high-pass filter, and a double-balanced demodulator. Two output channels of suitable response provide for simultaneous recording of instantaneous and mean flow. Each pickup sleeve is calibrated in vitro in terms of microvolts per flow rate. An electrical series calibrator provides the operational calibration. Past methods are reviewed and circuit details and design considerations are discussed. View full abstract»

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  • The Use of an Analog Computer for Analysis of Control Mechanisms in the Circulation

    Page(s): 1913 - 1916
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    Two approaches are presented to the study of regulation in the circulatory system. One consists of programming on an analog computer equations to represent part of the system and then, using suitable transducer, substituting the computer for the biological component. An example is presented in which a part of the mechanism which regulates arterial pressure (the carotid sinus) is simulated. The other approach involves simultaneous solution of equations derived to represent each system component. Simulation of a transient disturbance in blood distribution (Valsalva maneuver) is presented to illustrate the use of this approach in predicting the role of each component in determining over-all system behavior. View full abstract»

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  • Some Engineering Aspects of Modern Cardiac Research

    Page(s): 1917 - 1924
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    Classical investigation into the function and control of the heart has been conducted on anesthetized open-chested dogs. Unfortunately, both the anesthetics and the exposure of the heart affect cardiac function. Hence, more realistic information would be obtained if the heart could be studied in intact conscious animals. A system has been developed to make possible continuous analysis of the action of the heart in the healthy unanesthetized dog during its spontaneous activities. This system involves the continuous measurement of the pressure within the chambers of the heart, the size of these chambers, and the flow of blood out of the heart. Heart rate, stroke volume, average blood flow, effective cardiac power and work, and other information are continuously derived from the directly-measured parameters by means of analog computers. Several new instruments were developed to solve the problems unique to measurement in an intact animal. The dimensions of the heart chamber are obtained by measuring the transit time of pulsed sound passing across the chamber. Blood flow is measured by comparing the upstream and downstream transit times of bursts of sound passing through the moving blood. An isothermal flow meter utilizing a tiny thermistor on the tip of a catheter provides an alternate measure of flow. A miniature, differential transformer type of pressure transducer was developed for measuring pressure within a heart chamber. The system provides a means by which hypotheses regarding cardiovascular function and control may be rapidly and accurately evaluated. View full abstract»

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  • Stability, Oscillations, and Noise in the Human Pupil Servomechanism

    Page(s): 1925 - 1939
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    The pupil reflex to light has been considered as a servomechanism, a self-regulated error-actuated control device. This cybernetic approach, requiring the experimenter to make quantitative measurements in animals with a fully intact central nervous system, was made possible using a pupillometer designed for awake, cooperative human subjects. This instrument provided an electronically controlled light stimulus as well as continuous records of both pupil area and light intensity. Sinusoidal changes in light intensity, small enough for linearization assumptions, were injected in an open loop fashion to determine the transfer function for pupil system behavior. The pupil servo is quite stable and has a low gain with an attenuation slope of 18 db per octave beyond 1.5 cps. One line of investigation using pharmacological agents has suggested the triple lag to be contributed by the physical law representing the viscosity of the iris neuromuscular system. Another experiment used artificially increased gain to produce instability oscillations whose frequency was predictable from the low gain transfer function. Still another investigation has shown the pupil system to contain much noise. This noise is not a result of instability, nor generated by the smooth muscle of the iris, nor by other elements of the pupil servoloop, but is injected into the loop from another part of the brain. Further studies in progress are defining nonlinearities in the pupil and retinal system in order to set up an accurate analog model of the pupil system in the form of a program for a digital computer. View full abstract»

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  • What the Frog's Eye Tells the Frog's Brain

    Page(s): 1940 - 1951
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    In this paper, we analyze the activity of single fibers in the optic nerve of a frog. Our method is to find what sort of stimulus causes the largest activity in one nerve fiber and then what is the exciting aspect of that stimulus such that variations in everything else cause little change in the response. It has been known for the past 20 years that each fiber is connected not to a few rods and cones in the retina but to very many over a fair area. Our results show that for the most part within that area, it is not the light intensity itself but rather the pattern of local variation of intensity that is the exciting factor. There are four types of fibers, each type concerned with a different sort of pattern. Each type is uniformly distributed over the whole retina of the frog. Thus, there are four distinct parallel distributed channels whereby the frog's eye informs his brain about the visual image in terms of local pattern independent of average illumination. We describe the patterns and show the functional and anatomical separation of the channels. This work has been done on the frog, and our interpretation applies only to the frog. View full abstract»

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  • Repetitive Analog Computer for Analysis of Sums of Distribution Functions

    Page(s): 1952 - 1956
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    Many experimental procedures yield curves which are sums of distribution functions. Examples of such curves include electrophoretic, diffusion, and ultracentrifugal patterns, absorption spectra, and curves from countercurrent distribution and from partition chromatography in either liquid or vapor phase. In a given type of curve, each of the component functions is identical to the others in form (for example Gaussian) but can have very different values of the parameters governing height, width, and position along the abscissa. We wish to determine the parameters for each component by an analysis of the sum curve. The computer to be described performs this analysis by synthesizing a number of distribution functions of the desired form, each with adjustable parameters, and presenting, on an oscilloscope, the sum of these functions for comparison with the experimental curve being analyzed. A match is made visually by adjustment of the various parameters. When a match has been obtained, the parameters of the component functions are read out, following a switching procedure which presents the individual functions in sequence. View full abstract»

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  • Medical Ultrasonics: Introduction

    Page(s): 1957 - 1958
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    First Page of the Article
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  • Medical Ultrasonics: Absorption of Ultrasound by Tissues and Biological Matter

    Page(s): 1959 - 1962
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    General principles which determine the frequency dependence of both absorption and velocity of ultrasound in matter are outlined and applied to cell suspensions and tissues. The mechanisms which are responsible in the biological case for the experimentally observed frequency dependence of ultrasonic properties are described. They relate predominantly to macromolecular components. Finally, the relationships which pertain to the propagation of ultrasound in heterogeneous tissue complexes are discussed, and consequences for the medical application as a therapeutic tool are considered. View full abstract»

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  • Medical Ultrasonics: Diagnostic Applications of Ultrasound

    Page(s): 1963 - 1967
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    Current research on the use of low-power ultrasound as a diagnostic tool is reviewed. Ultrasonic waves can be used to investigate soft tissue structures which are opaque to light or invisible to X rays. Continuous-wave techniques can picture absorbing or reflecting areas in tissue specimens. Doppler frequencies related to the motion of the heart have also been investigated. Pulse reflection techniques can detect the small echoes reflected from interfaces between and within tissue structures. Radar scanning tecnhiques are used to form reflection pictures of accessible tissues. The significance of such pictures of the breast, bowel, eye, extremities, kidney, liver, and neck areas in the living human is being studied. The position and velocity of the walls of the heart during the cardiac cycle also can be recorded. View full abstract»

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  • Medical Ultrasonics: Applications of Ultrasound to Biologic Measurements

    Page(s): 1967 - 1970
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    The achievement of reliable and reproducible measurements in the broad field of the life sciences demands the highest level of competency among the experts who know how to measure. The new technology called "sonics" encompasses heretofore problematic industrial measurements with ultrasound. The application of sonics for measurement in the biologic sciences gives promise. Methods for measuring the velocity of blood, the viscosity of blood and certain dimensions of living bodily tissues are described in this report. View full abstract»

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  • The Use of Electronic Computers to Aid in Medical Diagnosis

    Page(s): 1970 - 1977
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    With the use of computers several mathematical techniques can be applied to aid certain aspects of medical diagnosis. However, much work remains to be accomplished in trying these methods under practical conditions. Although wide interest has been expressed, few studies have been reported in the literature. Among the potential advantages of computer aids are: making available to the physician quantitative methods in areas related to data analysis and differential diagnosis; assisting in the evaluation of the best alternative courses of action during stages of the diagnostic testing processes; and periodic recording and evaluating of individual physiologic norms for more sensitive determination of an individual's health trend relative to disease prevention. Communication between the physician or researcher and the computer is presently technically feasible but much research and planning are still required for realistic application. View full abstract»

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  • New Instrumentation Concepts for Manned Flight

    Page(s): 1978 - 1992
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    The advent of modern aircraft has forced the recognition of three fundamental principles required to optimize human flight control: The first, kinalog attitude display, is an adaptive kinesthetic analog tracing the human orientation as g force is sensed, intended to inhibit the onset of vertigo through the maintenance of continued agreement between the instruments and the human operator's internal "up" vector. The second, anticipatory display, describes information relative to some aspect of a future status of the vehicle, thus overcoming both the pilot's and the vehicle's response time lag. The speed of modern aircraft already leaves too little time for decision making. Anticipatory display may overcome this problem and significantly improve performance. The third, modified pictorial display, presents an integrated pictorial view from which has been removed much of the irrelevant data which would be seen in the real world. These concepts are embodied in proposed aircraft instrument designs which fall within the present state of the art. They are also extended to possible future spacecraft applications. Compatible quantitative instrumentation is also described to complete the cockpit panel. Cursory evaluation has been accomplished by ground simulation and some relevant data is presented. These initial experiments appear to offer a significant promise to increase the performance capability of future manned vehicles. View full abstract»

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Aims & Scope

This Periodical ceased production in 1962. The current retitled publication is Proceedings of the IEEE.

Full Aims & Scope