In (45b), θ ≡ t c1 /t s2 , and β has been introduced in (45a) to denote κ 1 /(1+κ 1 ). By inspection of (45a), it is clear that if δ S (1 + κ 1 )(1 + σ 1 ), then s 1 will be a slow variable over the t s2 timescale. Furthermore, as a result of the RSA and (45b), it is reasonable to assume that c 1 is close to its maximum value on the t s2 timescale, and