Research projects
Relevant journal paper [pdf] |
Diffusion in complex materials. We applied fluorescence correlation spectroscopy, traditionally used with a stationary or scanning confocal microscope, to a spinning disk confocal microscope, allowing spatially-resolved studies of flows and diffusion in inhomogeneous materials. We've applied our new technique to diffusing microspheres in collagen. A spatial map of the extracted diffusion coefficient is shown to the left. (w/ J. Urbach at GU) |
 paper [pdf] |
Magneto-rotational instability (MRI) in liquid sodium. The MRI (not
to be confused with the brain scanner) is a crucial element in accretion disks, the precursor
to planets, stars, galaxies and other astrophysical objects. Magnetic fields cause turbulence
and make the process happen much more quickly (without it, we may not be here yet!). We were
the first to observe this instability in an experiment, and we found it can occur in the
presence of preexisting (hydrodynamic) turbulence. More from
Maryland site. This was the topic of my
Ph. D. dissertation.
(w/ N. Mujica and D. Lathrop at UMD)
|
papers [pdf] [pdf] |
Experiments relevant to the Earth's core. We were trying to produce the first experimental self-sustaining dynamo in a minimally-constrained flow (inside a sphere, say, vs. a series of spiral pipes). Many different flow configurations (propellor type and orientation, baffles, etc.) were tried, and we learned a lot about (mostly) what doesn't work. Conclusion: a bigger experiment is needed. Learn about the upcoming 3 meter experiment, and more about dynamos, from the Maryland site. Featured in New Scientist, on the Discovery Channel and PBS's Nova. (w/ W. Shew and D. Lathrop at UMD) |
Relevant journal paper [pdf] |
2D granular polymer solution. Ping pong balls strung together simulated a polymer, which was placed in a simulated solvent consisting of motorized "squiggle balls" that change direction randomly after a collision. We measured the distribution of the polymer's size fluctuations, the first time this was done for an experimental 2D system. (w/ J. Prentis at UM-D) |
Relevant journal paper [pdf] |
Heavy nuclear collisions. At the Michigan State University cyclotron I was part of efforts to understand the nuclear equation of state. Large nuclei were collided inside a large soccer-ball shaped vacuum chamber with 300 detectors around the inside (the 4 Pi array), and all the reaction products and energies were determined. (w/ A. Nadasen at UM-D and MSU) |
