(11)

C dR= −εC′ dR+ (α − β) M′UV + ξV;
dt dt

(12)

and putting as before

M + αM′ = c1,   M + βM′ = c2,   C + εC′ = C3,

(13)

c1 dUc2VR = 0,
dt

(14)

c2 dV+ (c1U + ξ) R = 0,
dt

(15)