Physics Colloquium: Exploring soft low-dimensional structures in the cell: Fluctuations, mechanics, and geometry

Prof. Alex Levine, University of California, Los Angeles

Abstract: Biology provides us with a number of effectively one- and two-dimensional elastic structures. The cytoskeleton of cells abounds with long, stiff protein filaments organized into bundles and networks. Cells are bound by and contain a wide variety of membranes, some of which have complex geometries. These lower dimensional structures are sufficiently soft to be strongly fluctuating at ambient temperature.  In addition, evolution has engineered a plethora of cross-linking proteins and molecular motors that interact with these structures. 

In this talk, I discuss a few examples of the role of fluctuations in soft low-dimensional biological structures, introducing the fluctuation-induced (Casimir) interaction between linkers in filament bundles. The Casimir interaction drives a new type of first-order filament bundling transition, leading to a disordered “line glass” network.  I report on the collective mechanics of such filament networks. Finally, within a single bundle, I show that quenched-in braids introduce kinks (highly localized bends) in the time-averaged contour of the bundle, and explore how such kinks anneal over time. 

Tuesday, November 19, 2019 at 3:15pm

Regents Hall, 109
3700 O St. NW

Event Type

Academic Events


Students, Faculty/Staff


Georgetown College, Physics





Prof. Alex Levine, University of California, Los Angeles

Event Contact Name

Prof. Jeffrey Urbach

Event Contact Email

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