Sunday, July 1, 2012

Seeking simplicity in complex systems

One thing I really enjoyed and appreciated about the workshop this week has been the emphasis on developing "simple" models to describe systems that are structurally and chemically complex.
Here "simple" means that there are a just a few degrees of freedom and a few parameters in the model. "Complex" means there are many degrees of freedom.
Even when people are doing very large and demanding molecular dynamics simulations of solvated proteins the goal has been to understand the essential physics and chemistry of what is going on.

Here are a few examples.

Phil Geissler considered a  simple model for force generation in cellular processes, showing how Actin filament curvature biases branching direction.

Frank Brown considered an analytical model that could be used for Interpreting neutron spin echo experiments on lipid bilayer membranes without introducing a "fudge factor" for the value of the solvent viscosity that experimentalists had been using.

Abe Nitzan considered the simplest possible effective Hamiltonians that could be used to describe Electromagnetic and magnetic effects in molecular conduction.

Greg Voth discussed the importance of coarse graining and described an unbiased numerical method for reducing the dynamics of a protein to just a few sites. He then described recent work applying this to electron transfer in an iron hydrogenase.

Rob Coalson considered the problem of how a particular pore membrane protein worked. He considered how a polymer brush collapses when exposed to a critical concentration of binding nanoparticles. He found how the mean-field theory for a simple lattice gas type model could capture the phase transition associated with the collapse of the brush.

Dmitry Matyushov spoke about extending elastic network models for proteins to describe their response to external forces including local and global electric fields.

1 comment:

  1. HI Ross,
    Good to see to see you in Telluride! It was a great meeting.

    Thanks for your posts and summaries.