Joshua Weitz: Applying Math and Physics to Biological Research

by Ted Jou '99

Joshua Weitz '93 is an Associate Professor in the Biology Department at Georgia Tech, where he works across disciplines and relies on a strong foundation in math, physics, and computer science that he can trace back to his education in the Blair Magnet two decades ago. His research group ( includes ecologists, mathematicians, physicists and bioinformaticians, and he describes their areas of research as "Theoretical Ecology" and Quantitative Biology." The Weitz Group at Georgia Tech uses the tools of nonlinear dynamics, stochastic processes, and large-scale data analysis to study complex biological systems.

One area of Dr. Weitz's research is viruses, but as he explains: "There are viruses that affect not just humans but insects, plants, and microorganisms." His group studies the effects of viruses on communities of microorganisms in the oceans or other environments. Dr. Weitz is interested in the broad effects of these viruses on organisms and ecosystems. For example, his group has attempted to systematize and quantify the ability of viruses to cross-infect different species, looking for structural factors that affect when a virus may be able to infect one species but not another. He describes an interesting phenomenon of "co-evolution" where bacteria develop resistance to viruses and viruses evolve counter-resistance, and he is interested in how this persists in natural systems.

Another Magnet Alum at Georgia Tech

Dr. Weitz isn't the only Blair alum on the faculty at Georgia Tech. David Hu '97 is an Assistant Professor of Mechanical Engineering with a joint appointment in Biology. Dr. Hu received his B.S. and Ph.D. from MIT, and he completed a Postdoc at the Courant Institute.

The Hu Lab at Georgia Tech investigates the locomotion of animals, including the swarming behavior of ants, the ability of snakes to climb vertical surfaces, and the flight of mosquitoes in rain. In 2009, the Discovery Channel produced a short feature on Dr. Hu's research into the movement of snakes (watch on YouTube). In 2010, he was interviewed by Good Morning America about his research on how dogs and other animals shake themselves dry (watch on YouTube).

As an example of Dr. Weitz's cross-disciplinary research, Gabriel Mitchell, a graduate student in the Weitz group, recently published a journal article in collaboration with Kurt Wiesenfeld, a Professor of Physics at Georgia Tech, and Daniel Nelson, a Professor of Veterinary Medicine at the University of Maryland. The article is entitled "Critical cell wall hole size for lysis in Gram-positive bacteria," and it addressed the of question of when a hole in a cell wall becomes too big for bacteria to survive. The researchers developed a biophysical theory for how bacteria function normally with small holes that allow nutrients to enter the cell but are killed when larger holes are created by viruses or other causes. This theoretical model was then compared with experimental data estimating the critical size of holes in a cell wall that cause bacteria to die.Although he is now a Professor of Biology, Dr. Weitz only took the minimum number of biology classes at Blair, instead focusing on Physics and Computer Science. He was a Physics major at Princeton, and he remembers that after graduating from the Magnet, “my first year of Princeton didn’t seem that bad.” He also wrote a poetry thesis at Princeton and published a book of poems, Between Two Stones (available on Amazon). From Princeton, he pursued a Physics PhD at MIT, and in his first year of graduate school he switched to a biophysics group. He earned his PhD in 2003 with a thesis in mathematical biology and he returned to Princeton for a Postdoc in Ecology and Evolutionary Biology before joining the faculty at Georgia Tech in 2007.Dr. Weitz looks back fondly on his time at Blair, remembering it as "not conventional" but "remarkable" in the variety of classes and the depth of classes" he was able to take. Looking back, he now appreciates that the Magnet curriculum prevented students from specializing too early and taught a strong foundation that has helped him to explore different fields over the course of his career. He is still using the mathematical knowledge and the computer science algorithms he learned in the Magnet. All of his teachers were influential, but he particularly remembers how Ms. Ragan and Ms. Dyas taught him new ways to think about solving problems. And he credited Mr. Bunday for encouraging him to go beyond just answering the question "to explore ideas that I probably had no business exploring." Dr. Weitz also remembers the "spirited intellectual and social environment" of the Magnet and the excitement of being part of a group of fellow students that shared his curiosity about science. He has no doubt that the Magnet was "a very formative aspect of my education."