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. Author manuscript; available in PMC: 2019 Dec 20.
Published in final edited form as: Soft Matter. 2019 Apr 10;15(15):3264–3272. doi: 10.1039/c8sm01877d

Figure 1: Vortices in a 2D active nematic flow field.

Figure 1:

(a) An active nematic in which one of every ~15,000 MTs is fluorescently labeled. The resulting speckle pattern is suitable for quantifying the active nematic flow field using particle imaging velocimetry (PIV). (b) Velocity field obtained from the PIV analysis overlaid on a raw image of an active nematic containing sparsely labeled microtubules. (c) The Okubo-Weiss field extracted from the velocity field. Light shading specifies areas where Q<0, which indicates coherent flows. Dark shading shows regions where Q>0, which indicates diverging flows. The green circles indicate regions of coherent flows where there are vortices as defined by velocity field rotations of 2π. The area of the vortex is defined by the sum of the connected areas of Q<0 around a vortex center. Scale bars, 100μm.