External population supplied by belt removal
= External population supplied by belt removal
{title2=$n_{\rm out}=T n_b/t_y$}
A population supplied at differential number rate $n_b(D)/t_y(D)$ and surviving externally for a size-independent time $T$ has $n_{\rm out}(D)=Tn_b(D)/t_y(D)$. Its differential number slope changes by the negative of the removal-time exponent, unless the belt is already removal-dominated, in which case it reflects the fragment injection spectrum.