40 research outputs found
Hydrodynamic collective effects of active proteins in biological membranes
Lipid bilayers forming biological membranes are known to behave as viscous 2D
fluids on submicrometer scales; usually they contain a large number of active
protein inclusions. Recently, it has been shown [Proc. Nat. Acad. Sci. USA 112,
E3639 (2015)] that such active proteins should in- duce non-thermal fluctuating
lipid flows leading to diffusion enhancement and chemotaxis-like drift for
passive inclusions in biomembranes. Here, a detailed analytical and numerical
investigation of such effects is performed. The attention is focused on the
situations when proteins are concentrated within lipid rafts. We demonstrate
that passive particles tend to become attracted by active rafts and are
accumulated inside them.Comment: 12 pages, 7 figure
Anomalous diffusion and transport by a reciprocal convective flow
Under low-Reynolds-number conditions, dynamics of convection and diffusion
are usually considered separately because their dominant spatial and temporal
scales are different, but cooperative effects of convection and diffusion can
cause diffusion enhancement [Koyano et al., Phys. Rev. E, 102, 033109 (2020)].
In this study, such cooperative effects are investigated in detail. Numerical
simulations based on the convection-diffusion equation revealed that
anisotropic diffusion and net shift as well as diffusion enhancement occur
under a reciprocal flow. Such anomalous diffusion and transport are
theoretically derived by the analyses of the Langevin dynamics.Comment: 10 pages, 9 figure
Autonomous elastic microswimmer
A model of an autonomous three-sphere microswimmer is proposed by
implementing a coupling effect between the two natural lengths of an elastic
microswimmer. Such a coupling mechanism is motivated by the previous models for
synchronization phenomena in coupled oscillator systems. We numerically show
that a microswimmer can acquire a nonzero steady state velocity and a finite
phase difference between the oscillations in the natural lengths. These
velocity and phase difference are almost independent of the initial phase
difference. There is a finite range of the coupling parameter for which a
microswimmer can have an autonomous directed motion. The stability of the phase
difference is investigated both numerically and analytically in order to
determine its bifurcation structure