NONLINEAR ANALYSES OF PERIODIC AND CHAOTIC TIME-SERIES FROM THE PEROXIDASE OXIDASE REACTION

Experimental time series of [O2] generated by the peroxidase-oxidase r eaction were analyzed using various methods from nonlinear dynamics. T he following results were obtained: (1) Aperiodic time series are chao tic as evidenced by (i) the observation of period doubling bifurcation s in response to increasing the amount of 2,4-dichlorophenol in the re action mixture, (ii) well-defined next amplitude maps, (iii) positive Lyapunov exponents corresponding to about 0.5 bits per orbital excursi on, and (iv) fractal dimensions ranging from 2.6 to 2.8. Prediction pr ofiles obtained by subjecting the data to nonlinear forecasting give f urther evidence of deterministic chaos. (2) The chaotic data are nonun iform, since none of the above-mentioned methods work well when applie d to the continuous data. Instead, one has to use a series of maxima. (3) Conclusions 1 and 2 are supported by the fact that similar results obtain for chaotic time series generated by a simple model of the rea ction.