A modified fluctuation analysis of nonstationary processes

We consider a method of detrended fluctuation analysis (DFA method), which enables the study of long-range correlations in nonstationary processes. Its modification is proposed, including the calculation of additional quantity, that is, a scaling index, characterizing the effects of nonstationarity in the experimental data. Using the dynamics of the blood flow velocity in cerebral vessels as an example, the possibilities of a quantitative description of changes in the signal structure using the proposed modification of the DFA method have been demonstrated.