Fig. 8.

Dynamics of boundary-nucleated defects. Structure of circularly confined defect-laden active nematic in a weak confinement regime (Movie S7). Enlargements show sequence of images showing a boundary-induced defect nucleation and its subsequent rotation and alignment with the existing director field that reinforces the circular flow. Such dynamics produce long-lived compound $\pm \frac{1}{2}$ pairs featuring a $+1/2$ defect that pushes its oppositely charged counterpart for a substantial time before annealing. Confining diameter is 300 $\mathrm{\mu }$m.