We present a hydrodynamic model for a thin spherical shell of active nematic liquid crystal with an arbitrary configuration of defects. The active flows generated by defects in the director lead to the formation of stable vortices. analogous to those seen in confined systems in flat geometries. which generate effective dynamics for four +1/2 defects that reproduces the tetrahedral to ... https://www.chiggate.com/stagg-sdm70-dynamic-microphone-online-now/