Interview with Prof. Marsha I. Lester

The newly appointed Editor talks about her plans for The Journal of Chemical Physics

Lester received her Ph.D. from Columbia University in 1981. She has risen through the academic ranks at the University of Pennsylvania, where she is currently the Edmund J. Kahn Distinguished Professor and Chair of the Department of Chemistry. Lester has received many honors and awards, including her recent election to Fellowship in the American Academy of Arts & Sciences, the Bourke Lectureship of the Faraday Division of the Royal Society of Chemistry, a John Simon Guggenheim Memorial Foundation Fellowship, Fellow of the American Association for the Advancement of Science and the American Physical Society, an Alfred P. Sloan Research Fellowship, and the Camille and Henry Dreyfus Teacher-Scholar Award.

Imagine a dilute, flowing suspension of particles, which diffuse and collect on a seed in a thin planar region. Fractal manganese mineral deposits in rock layers are believed to grow in this way, driven by the diffusion of oxygen in slowly flowing water. What is the effect of fluid flow on the growth pattern? The video clip shows a simulation of advection-diffusion-limited aggregation (Ref. 1); a simple mathematical model of this phenomenon based on conformal mapping. The flow is very slow, so the fractal cluster grows symmetrically at first, driven mainly by diffusion (small Peclet number). The "cross section" of the cluster in the flow grows, however, so eventually advection dominates (large Peclet number). At long times, the cluster advances toward the flow (to the left) and yet keeps its original fractal dimension (1.71).

In our video, we examine avoided level crossings in the quantization of a particular system with mixed regular-chaotic dynamics.

Rheologists have created a new way of bullet-proofing clothes using shear-thickening fluids. Fabric treated with shear-thickening granular suspensions can turn soft material into solid protective gear when struck by a projectile. The treatment can strengthen Kevlar to produce lighter, more comfortable bullet-proof vests, or it can be used to turn extend the bullet-proof protection to ordinary fabric.