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Engineering in Medicine and Biology Society, 1989. Images of the Twenty-First Century., Proceedings of the Annual International Conference of the IEEE Engineering in

Date 9-12 Nov. 1989

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Displaying Results 1 - 25 of 1021
  • Images of the Twenty-First Century. Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society (Cat. No.89CH2770-6)

    Publication Year: 1989
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    Freely Available from IEEE
  • A cardiac gating device for MRI system

    Publication Year: 1989 , Page(s): 601 - 602 vol.2
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    An electrocardiograph (ECG) sensing device which is compatible with a magnetic resonance (MR) imager is described. It is used to synchronize the imaging sequences with a specific phase of the cardiac cycle. It is designed to detect the ECG signal and to generate a MR-sequence triggering pulse. Noise and artifacts induced by the radio-frequency pulses and magnetic field gradients inherent in MR imaging are electrically suppressed by using an isolated acquisition module and a fiber-optic cable to amplify and transmit the ECG signal.<> View full abstract»

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  • Identification of the time varying mechanics of isolated skeletal muscle

    Publication Year: 1989 , Page(s): 745 - 746 vol.2
    Cited by:  Papers (1)
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    A method for identifying the mechanics of systems with rapidly changing characteristics is presented for the case in which the characteristics of the system are changing in the same order of time as its dynamics. Results of muscle twitch experiments on frogs are presented. The length perturbation input and muscle force output data ensembles were analysed to yield instantaneous measures of muscle stiffness throughout a muscle twitch. The results clearly show muscle stiffness rising and then decaying during twitch. Stiffness as a function of force exhibits no hysteresis, and except at low forces, the relationship is linear. The variance accounted for at low forces is 0.6 compared with values greater than 0.9 at moderate and high forces. This departure from linearity at low forces indicates that nonlinear analysis of muscle mechanics must be performed View full abstract»

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  • A personal computer-based system for auditory evoked potential and psychoacoustic experiments

    Publication Year: 1989 , Page(s): 1277 - 1278 vol.4
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    An auditory evoked potential and psychoacoustic system which integrates a host personal computer with an Ariel DSP-16 digital signal processing board for optimal flexibility in the design and programming of experiments are discussed. The software on the signal processing board operates in parallel with the ASYST scientific language on the host computer. The system allows for the elaborate sequencing of digital stimuli and signal averages, in parallel with real-time processing for quality control. A library of easy-to-use macro functions is provided for customized algorithm development to realize innovative experimental protocols. Because the system is centered in a personal computer, it is an inexpensive yet powerful experimental tool View full abstract»

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  • A correlated multi-myoelectric channel model and its SNR characteristics

    Publication Year: 1989 , Page(s): 747 - 748 vol.2
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    A multi-myoelectric channel (multi-MEC) model for improvement of the signal-to-noise ratio (SNR) is presented. A channel performance analysis is carried out for the correlated multi-MEC. It is shown that the SNR depends on both physiological parameters such as mean firing rate and number of motor units and electric parameters such as correlation coefficient and the number of myoelectric channels View full abstract»

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  • Bayesian image reconstruction

    Publication Year: 1989 , Page(s): 483 - 484 vol.2
    Cited by:  Papers (1)
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    A Bayesian method is described for solving problems in image reconstruction from projections. The approach utilizes a Gibbs distribution to incorporate a priori spatial information. The model has been used for reconstruction of simulated data, data from phantom studies, and real scanning data. The results indicate that the technique has the potential to provide both improvement in spatial resolution and reduction of noise View full abstract»

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  • Visual evoked potentials and reaction times: dependence on alpha activity

    Publication Year: 1989 , Page(s): 1279 - 1280 vol.4
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    A reaction task consists of three sequential subtasks, perception, decision, and reaction, which can be modeled by a processing chain. Knowledge of the reaction time, which comprises the processing times of all stages, but normally does not impart knowledge about the single elements of the chain is discussed. An approach to separating processing times of single stages for the visual system by measuring the visual evoked potentials (VEP) is reported. The approach uses ongoing alpha activity and alpha blocking. Correlations between the time course of alpha blocking, the reaction time, and the parameters of the stimuli are shown and compared to the latencies of simultaneously recorded VEPs View full abstract»

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  • A coded summation method for measuring a visual evoked response

    Publication Year: 1989 , Page(s): 723 - 724 vol.2
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    A method for measuring visual evoked potentials (VEP) on humans at work is reported. The work consists of keying from a keyboard a character that is flashed on a screen, and a light stimulus evokes the visual response. There are two problems in this approach. One is that the energy of the light stimulus is less than that of the flash on the screen. The other is that the performance of work produces noise in the EEG. The coded summation method (CSM) is used to overcome these problems. The effectiveness of the CSM is evaluated. It is concluded that the CSM can measure the VEP in a shorter period of time than the usual averaged summation method, and it has higher reliability in detecting peaks in the EEG View full abstract»

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  • Microwave ablation for tachycardia

    Publication Year: 1989 , Page(s): 1141 - 1142 vol.4
    Cited by:  Papers (1)
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    Application of microwave energy delivered through a probe and a catheter in open- and closed-chest dogs to induce atrio-ventricular block is described. Several microwave antennas/catheters with a preferential power deposition at the tip were designed, constructed and tested. These antennas were designed for operation at 2450 MHz. Measurements in saline and tissue-equivalent liquid phantoms showed greatly increased heating at the tips of these antennas. The antenna consisted of flexible coaxial cables (1.78 mm OD) with a thin, semigrid brass sleeve just proximal to the tip. The entire antenna was insulated except for the tip and could be used for recording bipolar electrograms View full abstract»

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  • Relationships between SMES PSD and ACF main lobe width in localized muscle fatigue evaluation

    Publication Year: 1989 , Page(s): 1024 - 1025 vol.3
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    Theoretical and experimental work carried out to investigate the relationships between the mean frequency (fmean) of thesurface myoelectric signal (SMES) power spectrum, and the first zero crossing delay of its autocorrelation function (τ0) are discussed. An inverse relationship exists between these two parameters if the active motor unit pool does not change during a contraction and the main effect responsible for the power spectrum variation is the decrease of the muscle fiber average conduction velocity. In such a case, it is possible to demonstrate that the slope of the regression line between fmean and 1/τ0 does not change during the contraction and is related to the shape of the SMES power spectrum. The percent variations of fmean and τ0 are equal and opposite. Experimental data supporting the theoretical results are presented, as well as some applications to the analysis of the SMES View full abstract»

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  • Detection of spatial abnormalities in the EEG by spherical harmonic expansion

    Publication Year: 1989 , Page(s): 725 - 726 vol.2
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    The application of a spherical harmonic expansion to the spatial aspect of the electroencephalogram (EEG) is explored. Using the method of singular-value decomposition to estimate the coefficients of a truncated expansion, a spatially smoothed EEG is reconstructed. This smoothed EEG is then used to extract a localized feature. The application of this method to the general problem of the detection of localized abnormalities and artifacts is discussed View full abstract»

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  • Arres: computer assisted post anesthesia care unit monitoring system

    Publication Year: 1989 , Page(s): 1855 - 1856 vol.6
    Cited by:  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    A prototype system is being designed to provide advance warning of adverse respiratory and circulatory conditions in postanesthesia patients. The system is designed to minimize artifacts in the database, validate data for epidemiologic studies, and identify variables that predict adverse events through the application of artificial intelligence techniques and statistical models. The system is of modular design. The modules include the patient database, statistical model, interface to monitoring devices, rules for evaluating the monitor data, clinical knowledge, and advice View full abstract»

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  • Development of the physiological control scheme for an electrohydraulic total artificial heart

    Publication Year: 1989 , Page(s): 149 - 150 vol.1
    Cited by:  Papers (3)
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    A totally implantable artificial heart actuated by an electrohydraulic energy converter is described, and the requirements for its physiological control scheme are listed. Based on these specifications and on previous work on control schemes for the electrohydraulic total artificial heart, preliminary experiments were conducted which confirmed the feasibility of the proposed control scheme for the current device configuration. Experiments were conducted by attaching an electrohydraulic ventricle to pump the right side, and a pneumatic U-100 ventricle along with its drive and monitoring unit to pump the left side of an instrumented Donovan mock circulation. Each ventricle was controlled by manually adjusting its heart rate, percent systole, and drive pressures/motor speeds until the left and right atrial pressures were within 4 mmHg of each other, i.e. until the two sides of the circulation were balanced. The pressure waveforms sensed in the base of the electrohydraulic ventricle were recorded for a range of cardiac outputs (4-8.5 l/min) and of left atrial pressures (4-11 mmHg) View full abstract»

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  • Heat and water transport across the airway wall

    Publication Year: 1989
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    The thermal profiles in the airways of healthy human volunteers and patients with asthma differ following the cessation of hyperpnea. The asthmatics appear to have a greater ability to rewarm their airways. A model is developed that describes the radial transport of heat and water across the trachea which included a time-varying blood supply. Simulation results indicate that changes in tissue perfusion coupled with changes in mucosal thickness could account for the difference between the two groups View full abstract»

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  • Effects of electric fields on electron transfer in photosynthetic reaction centers

    Publication Year: 1989 , Page(s): 1320 - 1321 vol.4
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    Long-distance electron transfer in photosynthetic reaction centers has been manipulated using applied electric fields. Information on the nature of excited states and the participation of the intervening medium on the reaction rate has been obtained. Several models have been tested using this method, which selectively perturbs dipolar states. A reasonable model for long distance electron transfer in this system, which may be generally useful as the basis for designing molecular electronic devices, has been proposed View full abstract»

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  • Problems in evaluating image display systems

    Publication Year: 1989 , Page(s): 779 - 780 vol.2
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    The results of an evaluation of a commercial teleradiology system are presented. The efficacy of interpretation of skeletal radiographs from a digital image display on a CRT screen and from a plain film and light box station is compared. 122 single musculoskeletal radiographs were interpreted by four radiologists in the digital and analog format. Normal, subtle, and nonsubtle skeletal abnormalities were used. The digital image was interpreted on a CRT screen with a resolution of 1024×840×12 bits. Interpretation sessions simulated the actual clinical environment. Receiver operating characteristics (ROC) curves were generated to compare sensitivity and specificity over the full range of true positive and false positive values. The areas under the ROC curves have been shown to be a valid method of comparison between systems. After the study was performed and the results analyzed, the study was reviewed for potential problems with this type of evaluation. Some of these problems are discussed View full abstract»

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  • Pressure distribution beneath sensate and insensate feet

    Publication Year: 1989 , Page(s): 822 - 823 vol.3
    Cited by:  Papers (2)
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    To quantify the differences in foot pressure-time relationships between the sensate foot and diabetic insensate foot, the authors have collected foot pressure data from five sensate subjects and three diabetic insensate subjects during 4 min. of continuous walking for multiple trials. They used an insole instrumented with seven pressure sensors under the heel, metatarsal heads, and hallux and a microprocessor-based portable data-acquisition system for data collection. The peak pressures and the integral of pressure over time during the stance phase from each step were analyzed for both the sensate and insensate subjects. The authors obtained within-subject and between-subject variances for both peak pressure and pressure-time integral data View full abstract»

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  • Comparison of LPC algorithms for real-time speech processing

    Publication Year: 1989 , Page(s): 661 - 662 vol.2
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    Several methods for solving Yule-Walker equations, including the autocorrelation, covariance, lattice, and covariance-lattice algorithms, are investigated. Computational efficiency, memory requirements, stability, optimality, spectral resolution and fixed-point suitability of the algorithms are studied and compared. Such an analysis is required by real-time fixed-point implementations of linear predictive coding (LPC) of speech signals View full abstract»

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  • Automatic detection of metaphase chromosomes

    Publication Year: 1989 , Page(s): 350 - 351 vol.2
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    A system for automatic location of metaphase chromosomes was designed, implemented, and evaluated. Detection criteria were optimized for different chromosome preparations, and signal features were measured for each detected object. Discriminant function analysis was performed on data from a large number of slides in order to distinguish between debris and metaphases. It was found that discrimination between interphase nuclei and metaphases is relatively simple and can be accomplished at the level of detection, whereas debris presents a problem at the low magnification used. Nevertheless, in the case where debris was most abundant, the overall classification accuracy was over 80% View full abstract»

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  • Automatic recording of impedance in electrophysiologic electrodes in electrocardiography and evoked potentials

    Publication Year: 1989 , Page(s): 1545 - 1546 vol.5
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    A system is described for the control and measurement of the impedance of electrophysiological surface electrodes which can be used, parallel to the recording of the signal of interest, to determine instantaneously the value of the impedance of the sensor without disturbing the recording. The system works by creating a variation of current and then measuring the variation of the corresponding potential View full abstract»

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  • Weanpro: a weaning protocol expert system

    Publication Year: 1989 , Page(s): 1857 - 1858 vol.6
    Cited by:  Patents (3)
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    A description is given of WEANPRO, an expert system that assists respiratory therapists and nurses in weaning postoperative cardiovascular surgery patients from mechanical ventilation in the cardiovascular intensive care unit (CVICU). WEANPRO suggests ventilator settings that lead the patient toward independent breathing on the basis of arterial blood gas (ABG) analysis, spontaneous effort, and hemodynamics. WEANPRO was developed using M.1, an expert system shell, and runs on any 80286- or 80386-based personal computer. The expert system was developed to increase the quality and decrease the cost of the weaning process that occurs every day in the CVICU. An evaluation revealed that WEANPRO decreased the mean number of ABG analyses necessary to wean patients from 6.2 to 3.5. A one-tailed test of hypothesis revealed that WEANPRO's mean is statistically less than the clinicians mean with a t-statistic of -4.994 and a p-value of 2.3772E-6 View full abstract»

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  • The fundamental law of electrostimulation

    Publication Year: 1989 , Page(s): 84 - 85 vol.1
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    Physical interpretation is given to the fundamental formula of electrostimulation theory, which provides means for the estimation of dangerous thresholds for field strength, voltage, and current as a function of frequency. Between 20 kHz and 400 kHz the thresholds increase with 6 dB/octave. Above 400 kHz, an attenuation of 12 dB/octave makes fibers nearly insensitive to electrical excitation View full abstract»

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  • A biodomain model for simulating propagation in multicellular cardiac tissue

    Publication Year: 1989
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    The governing equations for evaluating propagation in a cylindrical bidomain are presented. The tissue model assumes equal anisotropy ratios. The simulations indicate that unlike the behavior noted in conventional one-dimensional models, the shape of the transmembrane potential, Vm, is affected by the conductivities. For mathematical simplicity, equal anisotropy is assumed, i.e., the ratio of the intracellular and interstitial conductivities is the same in the radial and axial directions View full abstract»

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  • Reduction of motion artifacts in computed tomography

    Publication Year: 1989 , Page(s): 485 - 486 vol.2
    Cited by:  Papers (2)  |  Patents (1)
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    The authors report on an analysis of motion artifacts by retrospectively reconstructing partial scan images, scanning moving phantoms, and using computer simulations of the scanner and moving object. The partial scan reconstructions eliminated some artifacts. Phantom and computer simulations substantially reproduced the clinical artifacts and provided insight into the relationships between motion, artifacts and scanner parameters. It is concluded that motion artifacts can be reduced by short scan times combined with gantry synchronization to align the X-ray beam along the axis of any residual motion View full abstract»

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  • Design and construction of a biominilab for biomedical research

    Publication Year: 1989 , Page(s): 1431 - 1432 vol.5
    Cited by:  Papers (1)
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    The authors report the design of an integrated electronic system that supplies the necessary functions of biomedical research. The equipment comprises the following modules: an amplifier of bioelectrical signals with rechargeable batteries as the power source, an electric current injector, a clamp system, a cassette recorder converted to modulate frequency, a multiplexor for four-channel recording of slow bioelectrical signals, an interphase which transforms a cheap common oscilloscope into a memory one, and a radiofrequency lesion generator View full abstract»

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