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Current research focuses on information processing in biological neural nets and related membrane processes, including hydrodynamics and considerations of theoretical membrane physics; see the detailed lecture notes 'Theoretical Membrane Physics: on the Many Shapes of Vesicles' (2001), of which the first three chapters are available to download from the internet, and Chapter 4, on fluctuation theory, can be obtained from the author. In the present context we concentrate on three closely related topics.
I. Theory of Cell Substrate Hydrodynamics
Cells possess a cytoskeleton, an elastic network that determines in part the elastic properties of the cell membrane. Cells on a substrate, a coated semiconductor for example, pose a true challenge to theory: all the more so when they are subject to the flow of the adjoining viscous fluid. This situation raises new questions, in particular whether continuum mechanics adequately describes the membrane, with its composite character, fluid and yet resistant to shear. In other words, to what extent can cell substrate hydrodynamics, including such phenomena as tank treading, be described simply yet realistically by theory? There is a standard reference for this phenomenon, and a few provocative but incomplete references also addressing it, but not much more.
II. Elementary excitations of the cell membrane in flow
The kind of problem described above becomes all the more interesting if one includes the thermal motions of the flow, so that the elementary excitations of the membrane are included. For this purpose the corresponding fluctuation theory should be developed.
III. Ciliated surfaces
The hydrodynamics of a surface covered with beating cilia is not well understood, despite the many biological systems in which it occurs. Usually the cilia are coordinated in "metachronic" waves, suggesting that hydrodynamic interaction among the cilia is important. How this coordination is even possible, in one-celled animals like paramecium (see figure), is a mystery. The integration of the observed hydrodynamics with the molecular mechanism of cilia as active cross-linked bundles of microtubules is also not satisfactorily understood.
Partners
Not only is there extensive feedback from Profs. Andreas Bausch (E22) and Roland Netz (T37) but there is also a close collaboration with Prof. Mark Peterson (Mount Holyoke College, South Hadley, MA).
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