Microscopic to mesoscopic: what can modular molecular motors teach us about the nature of active stress?

Coarse-grained hydrodynamic theories have proven invaluable to our understanding of active nematic liquid crystals. In general, these treatments succeed despite coarse graining out the microscopic details of the material, because they account for certain mesoscopic consequences of microscopic change. For example, changing the elastic constants in the nematic governing equations can account for microscopic differences in mesogen length and rigidity. However, no such treatment accounts for the microscopic nature of the stress itself. Here, we step towards rectifying this discrepancy by experimentally tuning the properties of stress-generating myosin motors in an actin based active liquid crystal. Within this system, we can begin to understand how systematically varying the microscopic properties of these motors affects the resultant active flow.