Fail Small, Fail Often: An Outsider’s View of Physiologic Complexity
We examine the hypothesis that the robustness of physiological time series results from allowing the underlying process to fail in small ways, and on a fairly regular basis. The notion of controlling such complex time series by suppressing their natural variability is argued to increase the likelihood of failure being catastrophic when it does occur. We also examine the hypothesis that the statistics of heart rate variability (HRV) are given by a tempered Lévy probability density function. Herein, we use the fractional probability calculus to frame our arguments as a new way to understand complex physiological dynamics. A self-induced nonlinear control is shown to induce a tempered Lévy process and is consistent with the hypothesis of disease being the loss of physiologic complexity made over 25 years ago.
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