Econophysics vs Cardiophysics: the Dual Face of Multifractality

Multifractality in physiological time series and notably in human adult heart rate has been primarily attributed to the Fourier phase ordering of the signal [1]. In contrast, the primary cause for the width of the multifractal spectrum in financial time series has recently been connected with fat-tailed distribution rather than phase ordering [2]. Reducing the source of multifractality of the human heart to nonlinear phase ordering may in fact not be entirely exhaustive or even correct. In the ultimate stress of the heart of the fetus during labour, there is an essential contribution of fat tails of the event distribution. Generally the multifractal spectra of the fetal heart rate during labour are considerably wider than the spectra for adults. We attribute the difference to the large shocks which have previously been shown to exhibit similar behaviour to financial index crashes [3].