Research

General

I'm currently working on stochastic models in biology. Updates soon!

PhD work

As a a Ph.D. student at the University of Arizona, I worked with Ibrahim Fatkullin, and was generally interested in:

  • Stochastic differential equations with singular coefficients
  • The Bessel process
  • Interacting stochastic particle systems which exhibit swarming/aggregation
  • The hydrodynamic limits of such systems
  • Models of collective behavior

In my PhD, I worked on a system of singularly-interacting stochastic particles of varying masses, which experience inelastic ("sticky") collisions. This system can be viewed as 2D overdamped gravity. A preprint is available:

When scaled appropriately, the hydrodynamic limit of the empirical mass density converges to the solution of a nonlinear Fokker-Planck equation, such as the Keller-Segel model of chemotaxis, or its generalization, the multispecies Keller-Segel model. These PDEs blow up in finite time, and form Dirac-type singularities. Such blow-ups correspond to coalescence in the particle system.

Here's a coarsening system of ~40k pairwise interacting particles, approximating blow-up in a many-species Keller-Segel system:

Note: This simulation in based on somewhat outdated numerics for detecting collisions. Nevertheless, the video is (for the most part) qualitatively correct. 🙂