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Haverford College
Departments of Physics and Astronomy
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Summer Research Opportunities for Students in Jerry Gollub’s Research Group

Gollub Lab

Swimming Cells

We are studying the swimming of micro-organisms, especially algal cells, in collaboration with Prof. Karl Johnson of Biology. Topics of current interest include:

  • Studying the statistics of swimming of different cell strains.
  • Determining the statistical properties of swimmers as a function of the cell concentration. Does collective motion occur at high concentration?
  • Determining whether modifying the viscosity of the fluid affects the flagellar beating cycle or the efficiency of the swimmer.
  • Studying the statistics of cells swimming in the presence of light, which they can sense.

Deformation of Granular Material

We are investigating the deformation and failure of sheared layers of floating particles with tunable fluid-mediated cohesive forces, which provide a model system for understanding the mechanical failure of disordered solids. This work complements investigations by collaborators at University of Pennsylvania who study metallic glasses, colloids, and carbon films. While the system to be investigated at Haverford is composed of macroscopic particles, the results will be compared with the failure of these smaller scale disordered systems. Novel features include the ability to modify the cohesive forces between particles, and the ability to determine the size distribution of deformation events as a function of strain rate. This work will continue work done by other students over the last several years.

Methods

Both investigations utilize precision tracking of particles in fluids, pioneered by postdoctoral fellows in our laboratory, as a powerful experimental tool. Both systems are characterized using statistical methods to describe nonlinear complex systems. And both take advantage of simplifications that are obtainable by studying complex phenomena in two dimensions.