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Biomedical Engineering, IEEE Transactions on

Issue 12 • Date Dec. 1986

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  • IEEE Transactions on Biomedical Engineering - Table of contents

    Publication Year: 1986 , Page(s): c1
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    Freely Available from IEEE
  • IEEE Engineering in Medicine and Biology Society

    Publication Year: 1986 , Page(s): c2
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    Freely Available from IEEE
  • Guest Editorial

    Publication Year: 1986 , Page(s): 1053
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  • Classifier-Directed Signal Processing in Brain Research

    Publication Year: 1986 , Page(s): 1054 - 1068
    Cited by:  Papers (10)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4047 KB)  

    Because of the difficulty of extracting useful information from brain electrical or magnetic field measurements, sensitive analytic methods are often required. "Open-loop" techniques for the choice of signal features and the testing of statistical hypotheses are often not sufficient for such problems. The sensitivity of analyses can be increased by "closed-loop" analyses which use feedback from the hypothesis testing to optimize the feature extraction and/or primary analysis to achieve maximal classification accuracy for a pattern recognition analysis which attempts to separate experimental or ciinical conditions. Signal processing algorithms whose parameters are set to maximize the strength of consequent inferences as measured by classifier performance could be called classifier-directed methods. This paper reviews the application of classifier-directed methodologies to waveform detection and categorical classification problems in brain research. Pattern recognition methods are shown to be a convenient way of incorporating expert knowledge in a statistical framework with minimal assumptions about the statistics of the desired or undesired components. View full abstract»

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  • Multichannel, Single Tral Event Related Potential Classification

    Publication Year: 1986 , Page(s): 1069 - 1075
    Cited by:  Papers (4)
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    We report on the effect of electrode placement and number of electrodes on the classification of single trial event related potentials (ERP's). The subjects read propositions relating fictitious people and their occupations while ERP's were recorded. The subjects decided if the proposition was correct or incorrect and responded as per instructions. The single trial, multichannel ERP data were classified using various methods, e. g., hold-out, leave-one-out, resubstitution. Several other factors were examined to determine their effect on ERP classification, including taking a majority vote among channels, using the single best channel, and averaging the data across channels for a single ERP. The results from other experiments are compared to those presented here. View full abstract»

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  • Classification of EEG Spatial Patterns with a Tree-Structured Methodology: CART

    Publication Year: 1986 , Page(s): 1076 - 1086
    Cited by:  Papers (6)  |  Patents (1)
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    The increasing use of computers in statistics has spawned a new generation of multivariate statistical techniques. Chief among these is a tree-structured approach to classification and regression analysis. The CART, or Classification and Regression Trees, program implements a recursive partitioning procedure based on an iterative search for best binary "splits" of data. Resultant classifiers consist of binary trees whose leaves determine class labeling. Extensive use of data resampling techniques replaces biased classifier performance measures. View full abstract»

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  • A Maximum Likelihood Method for Estimating EEG Evoked Potentials

    Publication Year: 1986 , Page(s): 1087 - 1095
    Cited by:  Papers (16)
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    The problem of EEG evoked potential (EP) estimation is basically one of estimating a transient signal embedded in nonstationary mostly additive noise; and as such it is well suited to a nonstationary estimation approach utilizing, for example, the Kalman filter. The method presented in this paper is based on a model of the EEG response which is assumed to be the sum of the EP and independent correlated Gaussian noise representing the spontaneous EEG activity. The EP is assumed to vary in both shape and latency; the latter is assumed to be governed by some unspecified probability density; and no assumption on stationarity is needed for the noise. With the model described in state-space form, a Kalman filter is constructed, and the variance of the innovation process is derived; a maximum likelihood solution to the EP estimation problem is then obtained via this innovation process. The method was tested on simulated as well as real EEG data. View full abstract»

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  • Classification and Detection of Single Evoked Brain Potentials Using Time-Frequency Amplitude Features

    Publication Year: 1986 , Page(s): 1096 - 1106
    Cited by:  Papers (14)  |  Patents (7)
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    The classification and detection of event-related brain potentials was investigated using signal processing and statistical pattern recognition techniques. Amplitudes at sampled time points and frequency quantities have previously been used as features. Improvements to these procedures were obtained by using features from the time-frequency plane to utilize the geometric relationship between time and frequency, capitalizing on the nonstationarity of the evoked potential signals. These features were transformed from the original data sets based upon a two-step classification/feature selection procedure which uses selected frequencies from step 1 as parameters for data filtering in step 2. Features were selected from the filtered data, classifiers were designed, and the estimated classification accuracies were computed. View full abstract»

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  • Enhancement of Event Related Potentials by Iterative Restoration Algorithms

    Publication Year: 1986 , Page(s): 1107 - 1113
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    An iterative procedure for the restoration of event related potentials (ERP) is proposed and implemented. The method makes use of assumed or measured statistical information about latency variations in the individual ERP components. The signal model used for the restoration algorithm consists of a time-varying linear distortion and a positivity/negativity constraint. Additional preprocessing in the form of low-pass filtering is needed in order to mitigate the effects of additive noise. Numerical results obtained with real data show clearly the presence of enhanced and regenerated components in the restored ERP's. The procedure is easy to implement which makes it convenient when compared to other proposed techniques for the restoration of ERP signals. View full abstract»

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  • Testing Correlated "BEG-Like" Data for Normality Using a Modified Kolmogorov-Sminov Statistic

    Publication Year: 1986 , Page(s): 1114 - 1120
    Cited by:  Papers (3)
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    The one-sample Kolmogorov-Smirnov goodness-of-fit test (KS) is designed for use with independent data and can be highly sensitive to correlated data. Standard critical values for KS cannot be used with data with known correlations. For data with EEG-like spectra (low frequency, high amplitude spectral peaks) an empirically derived correction for KS provides correct critical values and retains much of the power of the original KS. The. correction is based on a simple quadratic expression involving a parameter ¿ computed from zero-crossing measurements. View full abstract»

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  • A Multichannel Signal Processor for the Detection of Epileptogenic Sharp Transients in the EEG

    Publication Year: 1986 , Page(s): 1121 - 1128
    Cited by:  Papers (11)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2851 KB)  

    A high-speed multichannel signal processing system is described which is capable of performing automated detection of epileptogenic sharp transients (ST) in the electroencephalogram (EEG). The system is implemented with individually programmable microprocessors on the input channels, followed by a single-board microcomputer which correlates results obtained from each channel, and can process data played back from a tape recorder at a speed eight times the realtime recording speed. A multichannel correlation algorithm is used to enhance the performance of the system in the presence of muscle artifact (EMG). Results are presented showing that the multichannel correlation is capable of reducing, in some cases, both missed detections due to poorly defined ST's and false alarms due to EMG. View full abstract»

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  • The Analysis of Noisy Signals by Nonparametric Smoothing and Differentiation

    Publication Year: 1986 , Page(s): 1129 - 1133
    Cited by:  Papers (10)
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    While smoothing methods are commonly applied to noisy signals, this is not true for differentiation. Derivatives are often of intrinsic interest when analyzing biological dynamics, and as will be illustrated, they are useful for determining characteristic points (local extrema, inflection, and saddle points) in the curve, in the presence of noise. There are inherent difficulties in computing derivatives which might have inhibited wider usage. Kernel estimation is a statistical approach to nonparametric regression (i.e., without specifying a functional model for the signal), which allows detertining the signal itself and its derivatives from noisy data. This method is presented, together with its properties. The influence and the choice of the weight function (kernel) of the smoothing parameter and the treatment of boundary points deserve particular attention. View full abstract»

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  • An Efficient Formula for Estimating the Generalized Moments of the Power Spectral Density (PSD) Without Computing the Fourier Transform

    Publication Year: 1986 , Page(s): 1134 - 1136
    Cited by:  Papers (1)  |  Patents (1)
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    Estimates of the moments of the power spectral density (PSD) are derived from a rapidly converging series of weighted samples of the autocorrelation function (ACF). As a result of the rapid convergence of the weighting coefficients of this series, accurate PSD moment estimates are obtained from a small number of ACF samples without computing the Fourier transform of the time series, thereby greatly reducing the computational requirements for generatiing the generalized moments of the PSD. The general expression for the moment generating series is presented along with explicit expressions for computing the first four moments from which mean, variance, skewness, and kurtosis of the PSD are obtained. View full abstract»

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  • High-Frequency Electrocardiogram Analyzer

    Publication Year: 1986 , Page(s): 1137 - 1140
    Cited by:  Papers (2)  |  Patents (2)
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    We have developed a microprocessor-based analyzer for processing the high-frequency electrocardiogram. It has a signal band-width of 500 Hz, five times that of the standard clinical ECG. The device is programmed to isolate QRS complexes, to compute their first derivatives, and to dilate the time base so that the high frequency ECG's and their derivatives can be recorded on a restricted-bandwidth hard copy device such as a strip chart recorder or ECG machine. Also, the analyzer interfaces directly to a laboratory computer system for additional signal processing. View full abstract»

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  • Reduction of Heart Sounds from Lung Sounds by Adaptive Filterng

    Publication Year: 1986 , Page(s): 1141 - 1148
    Cited by:  Papers (32)
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    Auscultation of the chest is an attractive diagnostic method used by physicians, owing to its simplicity and noninvasiveness. Hence, there is interest in lung sound analysis using time and frequency domain techniques to increase its usefulness in diagnosis. The sounds recorded or heard are, however, contaminated by incessant heart sounds which interfere in the diagnosis based on, and analysis of, lung sounds. A common method to minimize the effect of heart sounds is to filter the sound with linear high-pass filters which, however, also eliminates the overlapping spectrum of breath sounds. In this work we show how adaptive filtering can be used to reduce heart sounds without significantly affecting breath sounds. The technique is found to reduce the heart sounds by 50¿80 percent. View full abstract»

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  • Power Spectral Analysis of Heart Rate Varability in Sudden Cardiac Death: Comparison to Other Methods

    Publication Year: 1986 , Page(s): 1149 - 1156
    Cited by:  Papers (110)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1487 KB)  

    Power spectrum analysis of heart rate variability is described and compared to four other reported methods, with respect to their efficacy as predictors of risk of sudden cardiac death (SCD). Approximate frequency domain representations were obtained for each. The underlying physiologic processes which may give rise to spectral components are considered. These methods were employed to analyze 24-h ambulatory ECG's of patient populations at different degrees of risk of SCD. Heart rate variability was found to be reduced in cardiac patients known to be at increased risk of SCD, when compared to those not at increased risk. These differences were greatest in power spectral methods. Thus, power spectrum analysis appears to be more effective than the other methods in segregating these populations, suggesting that this method may be useful in categorizing cardiac patients according to risk of sudden cardiac death. View full abstract»

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  • Quantitative Investigation of QRS Detection Rules Using the MIT/BIH Arrhythmia Database

    Publication Year: 1986 , Page(s): 1157 - 1165
    Cited by:  Papers (243)  |  Patents (8)
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    We have investigated the quantitative effects of a number of common elements of QRS detection rules using the MIT/BIH arrhythmia database. A previously developed linear and nonlinear filtering scheme was used to provide input to the QRS detector decision section. We used the filtering to preprocess the database. This yielded a set of event vectors produced from QRS complexes and noise. After this preprocessing, we tested different decision rules on the event vectors. This step was carried out at processing speeds up to 100 times faster than real time. The role of the decision rule section is to discriminate the QRS events from the noise events. We started by optimizing a simple decision rule. Then we developed a progressively more complex decision process for QRS detection by adding new detection rules. We implemented and tested a final real-time QRS detection algorithm, using the optimized decision rule process. The resulting QRS detection algorithm has a sensitivity of 99.69 percent and positive predictivity of 99.77 percent when evaluated with the MIT/BIH arrhythmia database. View full abstract»

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  • Rhythm Analysis of Arterial Blood Pressure

    Publication Year: 1986 , Page(s): 1166 - 1172
    Cited by:  Papers (4)
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    Rhythms identified in the power spectra of blood pressure and ECG recordings were used as probes of the intact cardiovascular control systems. A prominent vasomotor rhythm was detected in human subjects and experimental dogs, with a period ranging between 15 and 30 s. This rhythm did not depend on specific rhythms of heart rate but was dependent on the sympathetic nervous system, and was identified as a third-order rhythm of blood pressure. The parasympathetic nervous system appears to mediate a separate rhythm having a slightly shorter period. Another rhythm studied was a subharmonic of heart rate that appeared during episodes of tachycardia. Electrophysiological mapping of the ventricular surface in dogs revealed that tachycardia induced an alternating pattern of electrical conduction in ischemic areas of the ventricle, coincident with the appearance of subharmonics in pressure and ECG. Our results illustrate the potential utility of spectral analysis of cardiovascular signals in assessing cardiovascular regulation. View full abstract»

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  • Short Time Fourier Analysis of the Electromyogram: Fast Movements and Constant Contraction

    Publication Year: 1986 , Page(s): 1173 - 1181
    Cited by:  Papers (41)  |  Patents (1)
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    We applied short-time Fourier analysis to surface electromyograms (EMG) recorded during rapid movements, and during isometric contractions at constant forces. We selected a portion of the data to be transformed by multiplying the signal by a Hamming window, then computed the discrete Fourier transform. Shifting the window along the data record, we computed a new spectrum each 10 ms. We displayed the transformed data in spectograms or "voiceprints." This short-time technique allowed us to see time-dependencies in the EMG that are normally averaged in the Fourier analysis of these signals. Spectra of EMG's during isometric contractions at constant force vary in the short (10-20 ms) term. Moments of the spectral distribution show this variability. Short-time spectra from EMG's recorded during rapid movements were much less variable. The windowing technique picked out the typical "three-burst pattern" in EMG's from both wrist and head movements. Spectra during the bursts were more consistent than those during isometric contractions. Furthermore, there was a consistent shift in spectral statistics in the course of the three bursts. Both the center frequency and the variance of the spectral energy distribution grew from the first burst to the second burst in the same muscle. We discuss this pattern with respect to the origin of the EMG bursts in rapid movement. We also extend the analogy between electromyograms and speech signals to argue for future applicability of short-time spectral analysis of EMG. View full abstract»

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  • Uterine EHG Processing for Obstetrical Monitorng

    Publication Year: 1986 , Page(s): 1182 - 1187
    Cited by:  Papers (41)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3084 KB)  

    The temporal and spectral properties of the human uterine electromyogram are first described, related to two different situations: pregnancy and parturition. Thus, a parameter set is selected, and a discriminant analysis is performed, in order to obtain the best discriminant vector for these two situations. A dynamic control of the efficiency of the contractions during labor is described. The good results of this dynamic control permit us to propose a monitoring device providing information on contraction rate and efficiency. View full abstract»

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  • Passive Neuronal Membrane Parameters: Comparison of Optimization and Peeling Methods

    Publication Year: 1986 , Page(s): 1188 - 1196
    Cited by:  Papers (11)
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    The passive membrane properties of neurons allow characterization of neurons. This paper deals with comparison of optimization and peeling methods for passive membrane parameter estimation. Examples using computer-generated test data as well as biological data are used to illustrate the use of these two methods, showing that optimization methods are more accurate than peeling methods. View full abstract»

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  • A Microprocessor-Based Signal Processing System for Measurement of Vascular and Urethral Parameters

    Publication Year: 1986 , Page(s): 1197 - 1203
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3639 KB)  

    A relatively simple, flexible, and economical system is reported for processing biological signals which contain frequencies in the audio range. The microprocessor-based system has been tested successfully on ultrasonic scattered signals from blood and urine to provide diagnostic information in real-time. Measurements were obtained for average velocity, standard deviation of velocity (indicative of laminar and turbulent flow), relative flow rate, and relative cross-sectional area as functions of time. Comparison of these measures at various locations along a vessel, and at various times in the life of a patient, could help to detect stenotic zones and physiological changes associated with disease. View full abstract»

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  • Current Source Density Estimation Using Microelectrode Array Data from the Hippocampal Slice Preparation

    Publication Year: 1986 , Page(s): 1204 - 1212
    Cited by:  Papers (18)
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    The potentials recordable from the hippocampal slice using a microelectrode array are described assuming a model of neural current sources. Inverse Fourier filter techniques to compute the current source density (CSD) are described taking into account the uncertainty in knowledge of the height of the current source above the recording plane. A lower bound on the minimum necessary sampling interval is calculated as 100 ¿m. Another calculation indicates it is unlikely that current sources are detectable if they are further than 250 ¿m from the recording array. Inverse filters with relatively short focal distances avoid unnecessary attenuation of signals from more distant sources. View full abstract»

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  • GMDH Correction Modeling of Distorted Signals Recorded by Mandibular Kinesiograph

    Publication Year: 1986 , Page(s): 1213 - 1221
    Cited by:  Papers (1)
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    A new correction method is investigated for distorted measurement signals recorded by a mandibular kinesiograph, an electromagnetic device to quantify jaw movement by a magnetic transducer fixed on the mandible. The method employs a self-organized system identification known as a group method of data handling (GMDH). The proposed GMDH correction method has the capability to design a two-dimensional nonlinear autoregressive model which represents the relationship between distorted measurements and their corrected estimates of the mandibular displacement for the initial adjustment of kinesiographic signals under ferromagnetic influences. A computational procedure of a GMDH correction method is described in which the mathematical structure of a nonlinear autoregressive model is identified in a self-organized manner. Heuristic determination of a restricted sensor array zone of a kinesiograph is proposed to obtain effective fitness of a particular GMDH correction model which corresponds to each of the concomitant restricted zones. Corrected signals evaluated in the present study reveal a mean estimation error of 0.101 mm with a standard deviation of 0.125 mm which is regarded as highly accurate in a clinical sense. View full abstract»

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  • 1986 Index IEEE Transactions on Biomedical Engineering Vol. BME-33

    Publication Year: 1986 , Page(s): 1 - 16
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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