“…If the AKA-effect is present, it requires to study, instead of a diffusive approximation (1.7), hyperbolic approximations as in [40] (see also [5,6,22] and references therein), because the timescale of the AKA-effect is 'much faster' than that of the eddy viscosity. To track the symmetry condition we use the dynamical systems approach (see, e.g., [13,38,49,50]), that is we view the modulation equations (1.4) and (1.6) as an infinite-dimensional system of ordinary differential equations for the Fourier coefficients of solutions.…”