Bifurcation diagram varying γ. The bifurcation diagram of varying γ, showing the attracting regions. In (a) we show wide range of variation of γ, and in (b), a zoom near origin. For γ <γth(b) the trivial is attractor for all initial conditions (region Ic). For γ > γth(a), with respect to the coordinates of small equilibrium point , the trivial is attractor for regions I, Ia and Ib; and we have three possibilities: (1) for , the non-trivial is attractor for initial conditions in regions II and III; (2) for , stable limit cycle circulating unstable , in regions IIa and IIIa; and (3) for , trivial is attractor for regions IV and V. In the latter case, the way to reaching the trivial equilibrium is different for initial conditions in Ib and IV or V. The scales of vertical and horizontal axes must be multiplied by the factors shown in the legends to obtain the actual values.