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Aperiodic stochastic resonance ͑ASR͒ is a phenomenon in which the response of a nonlinear system to a subthreshold information-bearing signal is optimized by the presence of noise. We have previously characterized this effect by the use of cross-correlation-based measures. Here we apply a measure ͑transinformation͒ that directly quantifies the rate of(More)
The study of human cognition, and preoperative functional brain mapping, are facilitated through the use of magnetoencephalography (MEG). However, the noise present in such recordings is significant relative to the signals of interest. To circumvent this issue multiple trials are performed for the same task and an ensemble average is performed to increase(More)
Orthogonal frequency division multiplexed systems are particularly prone to errors due to clipping, since they typically have high peak-to-average power ratios. In this paper, we propose a more efficient clipping mitigation technique based on quasi maximum-likelihood detection which gives approximately 3 dB gain for the SER of 2 /spl times/ 10/sup -3/ and(More)
The lifting scheme is used to adaptively change a biorthogonal filter bank, which implements a discrete wavelet transform (DWT), for improved compression of an ECG waveform. The filter bank is initialized using a Haar wavelet and the associated filters are then lifted so as to minimize a reconstruction error. This error is based on the difference between an(More)
– The PR interval extracted from the surface electrocardiogram (ECG) may be used for the noninvasive assessment of autonomic nervous system (ANS) activity at the atrioventricular (AV) node. Accurate automated detection of the characteristic P wave onset and QRS complex onset is complicated by a number of factors including varying wave morphology, external(More)
We present a technique for dimension reduction. The technique uses a gradient descent approach to attempt to sequentially find orthogonal vectors such that when the data is projected onto each vector the classification error is minimised. We make no assumptions about the structure of the data and the technique is independent of the classifier model used.(More)
—A method to elucidate PP and PR electrocardiogram variability during periods of obstructive apnea based on averaged interval length is considered. R and P peaks are extracted from 28 pediatric subjects' ECG signal using a Hilbert transform based technique. Visual analysis of phasic changes during obstructive events indicate that 21 of 28 of subjects(More)