  We study the spatiotemporal patterns that emerge when an active nematic film
is topologically constraint. These topological constraints allow to control the
non-equilibrium dynamics of the active system. We consider ellipsoidal shapes
for which the resulting defects are 1/2 disclinations and analyze the relation
between their location and dynamics and local geometric properties of the
ellipsoid. We highlight two dynamic modes: a tunable periodic state that
oscillates between two defect configurations on a spherical shape and a tunable
rotating state for oblate spheroids. We further demonstrate the relation
between defects and high Gaussian curvature and umbilical points and point out
limits for a coarse-grained description of defects as self-propelled particles.
