  For each $q\in{\mathbb{N}}_0$, we construct positive linear polynomial
approximation operators $M_n$ that simultaneously preserve $k$-monotonicity for
all $0\leq k\leq q$ and yield the estimate \[ |f(x)-M_n(f, x)| \leq c
\omega_2^{\varphi^\lambda} \left(f, n^{-1} \varphi^{1-\lambda/2}(x)
\left(\varphi(x) + 1/n \right)^{-\lambda/2} \right) , \] for $x\in [0,1]$ and
$\lambda\in [0, 2)$, where $\varphi(x) := \sqrt{x(1-x)}$ and $\omega_2^{\psi}$
is the second Ditzian-Totik modulus of smoothness corresponding to the
"step-weight function" $\psi$.
  In particular, this implies that the rate of best uniform $q$-monotone
polynomial approximation can be estimated in terms of $\omega_2^{\varphi}
\left(f, 1/n \right)$.
