Fluctuation-induced dynamics of nematic topological defects

Area of Science:

• Physics, Biophysics
• Materials Science, Soft Matter

Background:

• Topological defects in biological systems often exhibit flow fields and stress patterns attributed to active stress generation.
• Understanding the origins of these patterns is crucial for comprehending biological self-organization.

Purpose of the Study:

• To investigate whether mesoscopic fluctuations, independent of active stresses, can generate flow and stress patterns around topological defects.
• To explore the nature of these fluctuation-induced patterns and their resemblance to those in active biological systems.

Main Methods:

• Numerical simulations using continuum fluctuating nematohydrodynamics.
• Analysis of flow patterns and stress fields around topological defects under varying fluctuation conditions.

Main Results:

• Mesoscopic fluctuations in orientational alignment or hydrodynamics independently produce flow patterns similar to active systems.
• Fluctuation-induced positive half-integer topological defects exhibit extensile- and contractile-like motion.
• Isotropic stress fields accurately reproduce experimentally measured stress patterns in epithelia.

Conclusions:

• Active stress generation is not always necessary to explain flow and stress patterns around topological defects in biological systems.
• Passive elastic stresses and nematic flow-aligning behavior govern fluctuation-induced defect dynamics.