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Sami C. Al-Izzi (1,2,3,4), Pierre Sens (3,4), Matthew S. Turner(5,6) and Shigeyuki Komura (7)
(1) School of Physics & EMBL-Australia node in Single Molecule Science, University of New South Wales, Sydney, Australia
(2) Department of Mathematics, University of Warwick, Coventry CV4 7AL, UK
(3) Institut Curie, PSL Research University, CNRS, Physical Chemistry Curie, Paris, France
(4) Sorbonne Université, CNRS, UMR 168, Paris, France
(5) Department of Physics & Centre for Complexity Science, University of Warwick, Coventry CV4 7AL, UK
(6) Department of Chemical Engineering, University of Kyoto, Kyoto 615-8510, Japan
(7) Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Tokyo 192-0397, Japan
“Dynamics of passive and active membrane tubes”, Soft Matter, Vol. 16, No. 40, pp 9319-9330, 28 October 2020, https://doi.org/10.1039/D0SM01290D
ABSTRACT: Utilising Onsager's variational formulation, we derive dynamical equations for the relaxation of a fluid membrane tube in the limit of small deformation, allowing for a contrast of solvent viscosity across the membrane and variations in surface tension due to membrane incompressibility. We compute the relaxation rates, recovering known results in the case of purely axis-symmetric perturbations and making new predictions for higher order (azimuthal) m-modes. We analyse the long and short wavelength limits of these modes by making use of various asymptotic arguments. We incorporate stochastic terms to our dynamical equations suitable to describe both passive thermal forces and non-equilibrium active forces. We derive expressions for the fluctuation amplitudes, an effective temperature associated with active fluctuations, and the power spectral density for both the thermal and active fluctuations. We discuss an experimental assay that might enable measurement of these fluctuations to infer the properties of the active noise. Finally we discuss our results in the context of active membranes more generally and give an overview of some open questions in the field.
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