Robert G. Harrison

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The population of persons living with HIV (PLWH) is growing older and more prone to developing other chronic health conditions. Disease progression has been shown to be related to quality of life (QoL). However, descriptions of chronic comorbid illnesses and the unique QoL challenges of older adults living with HIV are not well understood and have not been(More)
We employ surrogate data techniques and a new correlation dimension estimation algorithm, the Gaussian kernel algorithm, to uncover non-linearity in human electrocardiogram recordings during normal (sinus) rhythm, ventricular tachycardia (VT) and ventricular fibrillation (VF). We conclude that all three rhythms are not linear (i.e. distinct from a monotonic(More)
We describe an efficient algorithm which computes the Gaussian kernel correlation integral from noisy time series; this is subsequently used to estimate the underlying correlation dimension and noise level in the noisy data. The algorithm first decomposes the integral core into two separate calculations, reducing computing time from O(N3Nb) to O(N 1Nb ).(More)
We provide numerical evidence that the electrocardiogram data collected from pigs during induced ventricular fibrillation cannot be described by a monotonic nonlinear transformation of linearly filtered noise. To establish this we use surrogate techniques and apply two test statistics: ~1! the Takens’ maximum likelihood estimator of the(More)
INTRODUCTION Although modern defibrillators are nearly always successful in terminating ventricular fibrillation (VF), multiple defibrillation attempts are usually required to achieve return of spontaneous circulation (ROSC). This is potentially deleterious as cardiopulmonary resuscitation (CPR) must be discontinued during each defibrillation attempt which(More)
Ž . Temporal complexity of early ventricular fibrillation VF is re-assessed through measuring the correlation dimension Ž . D , entropy K and high-dimensional component s from electrocardiogram ECG recordings using the Gaussian kernel 2 2 algorithm. Seven representative ECG traces of induced VF among 53 pig subjects are selected for analysis. VF is found to(More)