Math’s Kao, Engineering’s Shen Win CAREER Awards

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George Washington University researchers Lien-Yung (Nyima) Kao, assistant professor of mathematics at the Columbian College of Arts and Sciences, and Yun Shen, assistant professor of civil and environmental engineering at the School of Engineering and Applied Science, each received Faculty Early Career Development Program (CAREER) awards from the National Science Foundation (NSF).

The award is the federal agency's most prestigious honor supporting research led by junior faculty who have the potential to serve as academic role models and to lead advances in their fields. The projects are funded over five years.

Currently, 16 GW faculty-including Kao and Shen-have active CAREER awards.

"NSF CAREER awards are a signifier of groundbreaking scholarship and excellence in teaching and mentorship," said Interim Vice Provost for Research Robert H. Miller. "These recipients exemplify the kind of bold, interdisciplinary researchers that are advancing knowledge and inspiring the next generation of innovators."

Kao's work explores questions in ergodic geometry, an interdisciplinary field connecting ergodic theory and geometry. Ergodic theory investigates systems that evolve over time-like planetary motion, weather patterns and stock markets. Geometry, meanwhile, studies the shape and structure of objects.

Ergodic geometry combines these perspectives, using tools from dynamical systems to address geometric problems. Kao's CAREER project aims to deepen our understanding of the relationship between an object's shape and key dynamical quantities associated with it. In his work, he eschews well-studied orderly systems by adding chaotic elements-testing how system theories hold up under stress.

"If a system has no bad points-if everything is perfect-then it can be well understood. But bad situations can completely destroy all the theories that we know," he said. "I like to break [systems] apart and see what happens when they look really nasty."

Instead of exploring tangible systems like planetary motion, Kao works with purely geometric objects that he manipulates and stretches to observe under extreme conditions. His computation process is "very old school," he said-relying on notebooks and blackboards rather than computer simulations. "I'm a pure mathematician," he explained. "This is very, very complex. Even for mathematicians, it's hard."

In addition to expanding mathematical knowledge, the CAREER award will fund the creation of a GW Experimental Mathematics Lab at Foggy Bottom. The lab will establish a collaborative and vertically integrated research environment where students gain hands-on learning and mentorship opportunities, preparing them to contribute to cutting-edge mathematical research.

At the same time, Kao, a Taiwanese-American immigrant, designed his project to enhance collaboration between the two nations' mathematical communities, including travel exchanges. "I hope to create more interactions with the schools, with the students and with the broader mathematical society," he said.

Indeed, Kao compares his research combining ergodic theory and geometry with his own dual immigrant identities. "These two [mathematical] areas were independent and somehow people found and started to appreciate their overlap," he said. "As an immigrant, I lived in Taiwan, then I moved to the U.S. Now I can provide opportunities for two places."

Pathogen project

Shen's research examines the transmission and control of environmental pathogens from a systems perspective: how disease agents propagate and thrive in environments like soil or water, how they interact with each other and with other particles and contaminants in those environments and how these interactions affect the spread of infection.

Her CAREER project focuses on municipal wastewater, which, once treated, is reused for farming, industrial processes, landscaping and even some forms of recreation. This wide scope of use, of course, makes it imperative to ensure that wastewater treatment removes all infectious pathogens.

Unfortunately, Shen said, intestinal (or enteric) viruses that cause human illness are often present in wastewater and can be a particular challenge to root out. In part, this is because even on the already-small scale of microscopic organisms and particles, a virus-a non-living scrap of biological material that can replicate itself only inside a living host cell-is particularly tiny. But Shen's focus is on viruses' tendency in aquatic environments to clump together with larger and more abundant microorganisms like bacteria (or with other environmental particles and contaminants like microplastics).

"In the real environment, viruses are always present with lots of other microorganisms, which can influence their transport and transmission," Shen said. "The concentration of bacteria in wastewater can be very, very, very high, and these particles can be very mobile in that environment, so they serve as carriers for other pathogens like viruses."

Bacteria may physically shield associated viruses from antiseptic treatments like UV light and even enhance viral transmission, Shen said, making infection more common and illness more severe.

The CAREER grant will allow Shen and her team to deeply investigate the full course of bacteria-associated enteric viruses in wastewater, from emergence to infection and beyond. They will explore the mechanisms by which these aquatic interactions between viruses and bacteria occur, measure the disinfection resistance and increased virulence of such associations and track their impact on the health of infected hosts-incorporating an immunological component beyond the scope of most engineering research.

"Normally, in the field of environmental engineering, we don't quite consider what kind of response humans will have to environmental pathogens after they enter the body," Shen said. "But in this research, we want to add this component to study how the immune system responds to those pathogens."

Shen will also use the CAREER grant to develop undergraduate and high school class modules exploring environmental pathogen transmission and control, deepening public understanding of a common municipal process that affects almost everyone.

It may be tempting to picture infectious pathogens as single, independent particles that behave according to laboratory conditions, Shen said. But that ignores how infection really works: as a relational process involving millions of environmental interactions. Developing a clearer picture of that process could help develop more effective methods of pathogen control in wastewater and, through that, better public health for everyone. That's a huge goal, but Shen believes federal research funding is a tool powerful enough to accomplish it.

"I always appreciate federal funding, because when I was a student, my research was also supported this way," she said. "It is a super important mechanism to train new generations of engineers and scientists, to guarantee the sustainable development of the whole field. With it, we can develop new technologies. We can have new and advanced knowledge. And that can better contribute to society."