Coarsening in surface growth models without slope selection

We study conserved models of crystal growth in one dimension (delta(t)z(x, t) = -delta(x)j(x,t)) which are linearly unstable and develop a mound structure whose typical size L increases in time (L similar to t(n)) If the local slope (m = delta(x)z) increases indefinitely, n depends on the exponent gamma characterizing the large-m behaviour of the surface current j (j similar to 1/\m\(gamma)): n = 1/4 for 1 less than or equal to gamma less than or equal to 3 and n = (1 + gamma)/(1 + 5 gamma) for gamma > 3.