Timothy S. Margulies
Johns Hopkins Univ., Baltimore, MD 21218
The acoustic properties of mixtures of actin filaments and alpha-actinin depend in a complicated way on both the concentration and affinity of the cross-linking protein for actin. The dependence of sound absorption and speed through actin filaments at low frequencies has been analyzed for one-dimensional waves in a viscoelastic medium. Estimates are made using rheology data for the complex modulus versus deformation rate for actin filaments including the effects of various amounts of concentration of alpha-actinin. Calculations of acoustic waves show the influence of the transition from an isotropic viscoelastic solid to a viscous fluid of actin bundles. The perturbative approach for nonlinear wave propagation in viscoelastic media was also applied to investigate gel properties and influences on waveform modification.