Fig. 4

Classification of variables. Variables of the full five-dimensional model are grouped according to their dynamical behavior. c _s(τ) is a slow variable, while x(t)=(c,a,o,r) are fast variables. Of these, (a,o,r) form the typically oscillatory PA-subsystem that is recapitulated by c. In the ε=1/t _c≪1 limit, the variable c _s(τ) slowly relaxes towards a period-averaged value 〈c _∞ (o(c))〉. Therefore, the full model can be accurately described by its projection onto the 2D (c _s,c) phase space