  In this paper we study a contracting flow of closed, convex hypersurfaces in
the Euclidean space $\mathbb R^{n+1}$ with speed $f r^{\alpha} K$, where $K$ is
the Gauss curvature, $r$ is the distance from the hypersurface to the origin,
and $f$ is a positive and smooth function. If $\alpha \ge n+1$, we prove that
the flow exists for all time and converges smoothly after normalisation to a
soliton, which is a sphere centred at the origin if $f \equiv 1$. Our argument
provides a parabolic proof in the smooth category for the classical Aleksandrov
problem, and resolves the dual q-Minkowski problem introduced by Huang, Lutwak,
Yang and Zhang (Acta Math. 216 (2016): 325-388), for the case $q<0$. If $\alpha
< n+1$, corresponding to the case $q>0$, we also establish the same results for
even function $f$ and origin-symmetric initial condition, but for non-symmetric
$f$, counterexample is given for the above smooth convergence.
