IEEE transactions on bio-medical engineering
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IEEE Trans Biomed Eng · Feb 2000
Quality driven gold washing adaptive vector quantization and its application to ECG data compression.
The gold washing (GW) adaptive vector quantization (AVQ) (GW-AVQ) is a relatively new scheme for data compression. The adaptive nature of the algorithm provides the robustness for wide variety of the signals. However, the performance of GW-AVQ is highly dependent on a preset parameter called distortion threshold (dth) which must be determined by experience or trial-and-error. ⋯ Both the direct GW-AVQ and a wavelet-based GW-AVQ are tested. The results show that a user specified PRD can always be reached regardless of the ECG waveforms, the initial selection of dth or whether a wavelet transform is used in conjunction with the GW-AVQ. An average result of 6% in PRD and 410 bits/s in compressed data rate is obtained with excellent visual quality.
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IEEE Trans Biomed Eng · Jan 2000
Microwave life-detection systems for searching human subjects under earthquake rubble or behind barrier.
A new sensitive microwave life-detection system which can be used to locate human subjects buried under earthquake rubble or hidden behind various barriers has been constructed. This system operating at 1150 MHz or 450 MHz can detect the breathing and heartbeat signals of human subjects through an earthquake rubble or a construction barrier of about 10-ft thickness. The basic physical principle for the operation of a microwave life-detection system is rather simple. ⋯ If the clutter consisting of the reflected wave from stationary background can be completely eliminated and the reflected wave from the human subject's body is properly modulated, the breathing and heartbeat signals of the subject can be extracted. Thus, a human subject buried under earthquake rubble or hidden behind barriers can be located. This system has been tested extensively in a simulated earthquake rubble in the laboratory and also in a field test using realistic earthquake rubble conducted by a Federal Emergency Management Agency (FEMA) Task Force.
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IEEE Trans Biomed Eng · Jul 1999
Comparative StudyCanine sternal force-displacement relationship during cardiopulmonary resuscitation.
A viscoelastic model developed to model human sternal response to the cyclic loading of manual cardiopulmonary resuscitation (CPR) [8] was used to evaluate the properties of canine chests during CPR. Sternal compressions with ventilations after every fifth compression were applied to supine canines (n = 7) with a mechanical resuscitation device. The compressions were applied at a nominal rate of 90/min with a peak force near 400 N. ⋯ The elastic force and damping decreased with time and decreasing lung volume. Canine and human [8] model parameters were found to be similar despite the notable differences in thoracic anatomy between the species, supporting the continued use of canines as models for human CPR. These parameters may be useful in the development of a model relating sternal compression forces to blood flow during CPR.
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IEEE Trans Biomed Eng · Jun 1999
A stochastic model of the electrically stimulated auditory nerve: pulse-train response.
The single-pulse model of the companion paper [1] is extended to describe responses to pulse trains by introducing a phenomenological refractory mechanism. Comparisons with physiological data from cat auditory nerve fibers are made for pulse rates between 100 and 800 pulses/s. ⋯ Second, while interpulse effects such as refractory effects do indeed increase the dynamic range at higher pulse rates, both the physiological data and the model indicate that much of the dynamic range for pulse-train stimuli is due to stochastic activity. Third, it is shown that the stochastic model is able to predict the general magnitude and behavior of variance in discharge rate as a function of pulse rate, while the deterministic model predicts no variance at all.
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IEEE Trans Biomed Eng · Jun 1999
A stochastic model of the electrically stimulated auditory nerve: single-pulse response.
Most models of neural response to electrical stimulation, such as the Hodgkin-Huxley equations, are deterministic, despite significant physiological evidence for the existence of stochastic activity. For instance, the range of discharge probabilities measured in response to single electrical pulses cannot be explained at all by deterministic models. Furthermore, there is growing evidence that the stochastic component of auditory nerve response to electrical stimulation may be fundamental to functionally significant physiological and psychophysical phenomena. ⋯ Comparisons with physiological data from cat auditory nerve fibers are made, and it is shown that the stochastic model predicts discharge probabilities measured in response to single biphasic pulses more accurately than does the equivalent deterministic model. In addition, physiological data show an increase in stochastic activity with increasing pulse width of anodic/cathodic biphasic pulses, a phenomenon not present for monophasic stimuli. These and other data from the auditory nerve are then used to develop a population model of the total auditory nerve, where each fiber is described by the single-fiber model.