Building Bridges Across Disciplines

October 15, 2012—Professor of Physics Jeff Urbach has been named the first Interdisciplinary Chair in Science at Georgetown University. Urbach, who is also the inaugural chair of the Institute for Soft Matter Synthesis and Metrology, received the honor from Georgetown College in recognition of his ongoing collaboration with other science departments.

Since coming to the Hilltop 16 years ago, Urbach has been interested in combining physics with other disciplines in order to solve real-world problems. These connections—often years in the making—have helped him create research methodologies that solve phenomena in creative ways. He has formed working relationships with Associate Professor of Biology Heidi Elmendorf, Professor of Chemistry Paul Roepe, and hopes to start a project soon with Associate Professor of Biology Maria Donoghue

“I wanted to branch out, in part because I was interested in learning how to apply the tools and techniques that I had to biological problems—[not just] because these problems were interesting and were obviously important, but also because being at Georgetown, it made a lot of sense, especially because of my proximity to the [Georgetown University] Medical Center,” Urbach said.

According to Urbach, in the last two decades interdisciplinary research has become more common for physicists at research institutions. He attributes this to the fact that different departments will often have complementary perspectives on shared scientific questions.

“There’s a lot about what’s going on in the biological environment that a physicist is not going to understand well. But in many situations, the understanding of the physical phenomena going on requires a physicist,” Urbach explained. “The way a physicist typically works is to make an idealized model of something. The trick is to do an idealization that is simple enough that you can solve the problem but is not so simple that it’s irrelevant to the real world. That requires a lot of back and forth [between departments], and that’s kind of the fun part.”

For the past five years, Urbach has been working closely with Heidi Elmendorf in an effort to better understand the Giardia parasite, which is common in underdeveloped countries with poor health care and nutrition. Urbach and Elmendorf are investigating how the parasite manages to adhere to the intestinal lining of its hosts.

“In order to do its thing, the parasite—this little single-celled [organism]—needs to attach itself to the wall of the intestine and stay there and resist the forces that would normally push things like food through the intestine. It turns out that the community does not know the mechanism by which it attaches,” Urbach said. “For most biological [systems], when one thing attaches to another, it’s some sort of chemically mediated attachment, some sort of bonding. But there was evidence in the literature [saying] that was not what was going on here.”

Through their collaboration, Elmendorf and Urbach discovered that the parasite clings to the intestine using the microscopic equivalent of a suction cup and a vacuum cleaner.

While suction cups easily stick to impermeable surfaces like glass, the wall of the intestine is permeable, meaning liquids can flow through it as the Giardia parasite hangs on. In order to maintain the air pressure needed for suction beneath its ‘cups,’ the parasite uses its flagella—tail-like structures—to “act like a pump,” Urbach said, to rhythmically “beat” and “wave” out the fluid that leaks in.

“Now that we’ve got this figured out, there’s a whole bunch of additional things we would like to do to build on what we’ve learned,” Urbach said. His next goal will be to simulate Giardia’s environment, the intestine. Just like other soft matter materials, the intestine has both solid and liquid properties, making it a perfect project for a physicist.

“In fact, it’s interesting—and this is all stuff that I’ve recently learned—but the center part of the intestine is more of the stuff that’s in the liquid phase, and as you get to the wall it gets more and more solid-like, but it’s not a sudden transition. It’s a gradation.”

—Brittany Coombs