Equation Icon  dR- = e(μ−λ)(s,R)----W------, (40 ) ds E (R,W, L ) dW L ----= − λt(s,R )W − e(μ−λ)(s,R )μr (s,R )E (R,W, L ) + e(μ− λ)(s,R)--3-----------, (41 ) ds R E (R, W, L )