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Biomedical Engineering, IEEE Transactions on

Issue 3 • Date May 1976

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Displaying Results 1 - 17 of 17
  • President's message

    Page(s): 181
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    Freely Available from IEEE
  • Identification of Human Chromosomes by Using Integrated Density Profiles

    Page(s): 182 - 192
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    The discovery of new stains for chromosome preparations has made useful automated chromosome analysis possible. Appropriate descriptors for use in this process must be found and tested. Data compression using integrated intensity and density profiles has already proven valuable. View full abstract»

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  • A Mathematical Model of the Vagally Driven SA Nodal Pacemaker

    Page(s): 192 - 199
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    A model is developed for the vagal control of SA nodal activity in the heart and consists essentially of a modified Bonhoeffer-Van der Pol (BVP) model of the ``free-running'' SA node and a lumped model of the neural terminations in that region. The model is capable of mimicking both the driven transient behavior of the node in terms of pacemaker and inhibition curves, as well as steady-state entrainment phenomena. The model data also agree very well with experimental data from dog experiments performed in our laboratory. The model is described by a set of nonlinear, third-order, ordinary differential equations and provides a relatively uncomplicated functional model of heart period changes due to vagal stimulation patterns. View full abstract»

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  • Use of Non-Linear Programming and Stochastic Modeling in the Medical Evaluation of Normal-Abnormal Liver Function

    Page(s): 200 - 207
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    A model for Rose Bengal transport through the hepatobiliary system has been developed, and non-linear programming techniques have been used to derive the model's parameters according to actual patient data. The model is then further analyzed as a Markov chain. A system of checks and balances, and measure of error, is discussed. View full abstract»

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  • An Analysis of Chorioretinal Thermal Response to Intense Light Exposure

    Page(s): 207 - 215
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    An analytical expression has been obtained for the transient temperature distribution produced when the retina is irradiated by a high-intensity light source. The following factors are included in the analysis: (1) structurally the fundus consists of layers of material which have different physical properties, (2) absorption of energy from the light beam follows the Beer-Lambert law, (3) energy is absorbed in the sclera as well as in the pigment epithelium and choroid, (4) heat is removed from the fundus by blood circulating through the capillaries of the choroid, and (5) intensity of the light source may vary with time. Computed values indicate that absorption of energy in the sclera and removal of heat by convection are both important for longer irradiation times, which agrees with recent experimental observations. The asymptotic response to a train of pulses is presented also. View full abstract»

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  • Automated Assessment of Atrioventricular Conduction in the Heart

    Page(s): 215 - 219
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    After a pacemaker impulse passes along the atrioventricular conducting pathway of the heart, that tissue resists subsequent conduction for a time interval known as the ``effective refractory period.'' Effective refractory period (ERP) and transit time of conducted impulses vary in response to drug, hormonal and electrical influences and may be used as indicators of the immediate physiologic state of intracardiac conduction. The traditional manual technique for measurement of ERP and conduction time consists in repeatedly adjusting a pulse generator until conduction of a stimulus of minimum interval can be observed on a chart recorder or oscilloscope. In contrast to the slow, imprecise and tedious manual method, the automated system described here provides whole graphs of ERP and conduction times as functions of external pacing interval or intervals of induced premature beats with a minimum of operator intervention. Thus, atrioventricular conduction can be conveniently assessed by machine, while the human intellect is freed to dwell on the abstractions of interpreting results and controlling the overall measurement environment. View full abstract»

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  • Latent Components in the Electrocardiogram

    Page(s): 220 - 224
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    A new decomposition technique useful for representing a set of observed electrocardiograms is presented. This decomposition is different from past techniques in the constraints placed on the component waveforms in that they must be positive and start, stop, and overlap in a prescribed manner. The number of component waveforms is dependent on the maximum error tolerated in the reconstruction of the observed waveforms from the component representation. View full abstract»

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  • Delay Time Models of Population Dynamics with Application to Schistosomiasis Control

    Page(s): 225 - 233
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    Replacing the usual principle of conservation of numbers with the equivalent principle of continuity of flow leads to a very heuristic approach to modeling time lags in population dynamics. The approach allows the direct use of unequal time lags without the implicit assumption of a stable age distribution. It is directly applicable to certain endemic and epidemic diseases. Where time lags occur in the incubation or life cycle of the agent of such a disease, they often importantly affect the dynamics associated with the disease, yet they seldom are accounted for properly. View full abstract»

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  • An In Vivo Study of Cardiac Pacemaker Optimization by Pulse Shape Modification

    Page(s): 233 - 239
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    This paper is an experimental extension of theoretical work previously published by one of the authors. Results of pacing a canine heart using four different increasing exponential and ramp-like waveforms are presented. It is shown that these waveforms reduce the cardiac threshold energy by as much as 14 percent when compared with a pure rectangular pulse shape and by about 21 percent when compared with a standard cardiac pacer pulse. It is also found that above threshold energy is reduced by 50-60 percent. These results offer promise of increasing the life of certain new pacer power sources currently being tested. In addition, it may now be possible to pace at lower energy levels, thereby reducing tissue damage near the stimulating electrode, without running as much of a risk of exit block as with a comparable rectangular pulse pacer. View full abstract»

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  • Digital Imaging of Gamma-Ray Sources with Depth Information

    Page(s): 239 - 246
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    A digital method for imaging gamma-ray emitting organs recorded through a Fresnel zone plate (FZP) aperture is described. This technique can be used in an almost real-time recording and imaging system to yield quantitative and qualitative cross-section and depth information of the source. Furthermore, this method avoids some of the problems introduced by the usual method of optical reconstruction. Experimental results of the recording of a multiplane gamma-ray source and the reconstruction of digitally and optically formed images are also presented. View full abstract»

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  • A Waveform Analyzer Applied to the Human EEG

    Page(s): 246 - 252
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    This paper presents an approach to signal waveform analysis in the frequency range of 1 to 50 Hz. The technique is applicable to any waveform which is a single-valued function of time with continuous derivatives. The main application of this system has been on the human EEG. The analyzer, to be described, performs its analysis in the time domain and abstracts wave shape information from the original wave and from the successive mathematical derivatives of that wave. The output from this analyzer consists of six analog descriptors of the input EEG wave. These descriptors are basic amplitude and basic frequency of the original input wave, amplitude and frequency of the first derivative of the input wave, and amplitude and frequency of the second derivative of the input wave. View full abstract»

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  • An Improved Control Algorithm for an Artificial ß-Cell

    Page(s): 252 - 255
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    With the successful implementation of a computer analog for (ß-cell function to restore normal glucose tolerance in diabetic patients, one of the major obstacles to the ultimate development of an implantable ``artificial pancreas'' was overcome. The next step was to optimize the original algorithm and simplify the operation of the blood sugar control system to make it more amenable to miniaturization. View full abstract»

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  • A First Look at the Application of Signal Extraction Techniques to the Analysis of Body Surface Potential Maps

    Page(s): 256 - 262
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    Partial body surface potential maps from both normal subjects and subjects with independently diagnosed myocardial infarcts are visually compared from superimposed plots. A correlation test is devised to distinguish the two groups, with the reference waveform determined by means of a gradient-search algorithm. The results are encouraging, and suggest further investigation of these techniques as a future diagnostic tool. View full abstract»

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  • A Flexible Renewal Process Simulator for Neural Spike Trains

    Page(s): 262 - 266
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    Certain neuronal spike trains may be viewed as stochastic, nonhomogeneous point process. Neuronal information may be encoded in the time-varying mean rate of the spike train in some cases. For this purpose the simulator can be modulated by arbitrary time-varying voltage waveforms. View full abstract»

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  • The Urinary Drop Spectrometer - An Electrooptical Instrument for Urological Analysis Based on the External Urine Stream

    Page(s): 266 - 269
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    This communication presents the design and an outline of clinical experience with two models of the urinary drop spectrometer (UDS), a noncontact optical instrument used for assessing urological abnormalities based on observation of the external urinary stream. View full abstract»

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  • Comments on "Propagation of Plane Waves Through Two Parallel Dielectric Sheets

    Page(s): 269 - 270
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    It is pointed out that only the second dielectric wall of an irradiation chamber determines the voltage standing wave ratio within the chamber. Extension of the general method to more complex models is easily accomplished using numerical methods. View full abstract»

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  • Contributors

    Page(s): 270 - 272
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    Freely Available from IEEE

Aims & Scope

IEEE Transactions on Biomedical Engineering contains basic and applied papers dealing with biomedical engineering. Papers range from engineering development in methods and techniques with biomedical applications to experimental and clinical investigations with engineering contributions.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Bin He
Department of Biomedical Engineering