Effective Temperature of Red Blood Cell Membrane Fluctuations

E. BEN-ISAAC, Z. Y. K. PARK, G.POPESCU, F. L. H. BROWN, N. S. GOV AND Y. SHOKEF
Phys. Rev. Lett. 2011 106 238103 https://doi.org/10.1103/PhysRevLett.106.238103

Biologically driven nonequilibrium fluctuations are often characterized by their non-Gaussianity or by an ‘‘effective temperature’’, which is frequency dependent and higher than the ambient temperature. We address these two measures theoretically by examining a randomly kicked particle, with a variable number of kicking motors, and show how these two indicators of nonequilibrium behavior can contradict. Our results are compared with new experiments on shape fluctuations of red-blood cell membranes, and demonstrate how the physical nature of the motors in this system can be revealed using these global measures of nonequilibrium.