Bacteria swim through fluids by rapidly turning their flagella, and individual tissue cells migrate across surfaces in a cyclic process of expansion, adhesion, and retraction. These canonical types of motion, however, are not characteristic of cells within large, dense aggregates, such as bacterial...

Tidal flow over topography in a density-stratified ocean leads to the generation of internal waves. When these internal waves break, mixing of heat and salt can occur which may play a role in the large-scale ocean overturning circulation. I will describe numerical simulations of the nonlinear...

Swarming bacteria move in multicellular groups and exhibit adaptive resistance to multiple antibiotics. Analysis of this phenomenon has revealed the protective power of high cell densities to withstand exposure to otherwise lethal antibiotic concentrations. We find that high densities promote bacterial...

The dynamics of frictional slip have been studied for centuries yet many aspects of these everyday processes are not understood. One such aspect is the onset of slip. First described by Coulomb and Amontons as the transition from static to dynamic friction, the onset...

We have conducted both experiments and numerical simulations to investigate supersonic cracks. The experiments are performed at 85 oC in order to remove strain-induced crystallites that complicate experiments at lower temperature. Shear and longitudinal sound speeds are measured to find the...

In shallow temperature gradients, changes in temperature that bacteria experience occur over long time-scales. Therefore slow processes, such as adaptation, metabolism, chemicals secretion, and even gene expression become important. Since all these changes are related to cellular activity, the cell density...