College of Sciences Names 2016 Cullen-Peck Fellows

Awards recognize innovative research of Tamara Bogdanovic, Andrew Newman, Frank Stewart, and Lewis Wheaton.

The College of Sciences has selected the 2016 recipients of the Cullen-Peck Fellowships in the College of Sciences: Tamara Bogdanovic, an assistant professor in the School of Physics; Andrew V. Newman, an associate professor in the School of Earth and Atmospheric Sciences, Frank J. Stewart, an assistant professor in the School of Biological Sciences, and Lewis A. Wheaton, an associate professor in the School of Biological Sciences.

“The fellowships recognize exciting research accomplishments by College of Sciences faculty at the associate professor or advanced assistant professor level,” says College of Sciences Dean Paul M. Goldbart. “The goal is to help recipients take their research programs in new directions.”  

The fellowships are made possible by a generous gift to the College of Sciences from alumni Frank H. Cullen (B.S. in Mathematics with Honors 1973, M.S. in Operations Research 1975, Ph.D. Engineering 1984) and Libby Peck (B.S. in Applied Mathematics 1975, M.S. in Industrial Engineering 1976). 

“We in the College of Sciences are grateful for the generosity of alumni who encourage our faculty to take intellectual risks in their research,” Goldbart says. “The Cullen-Peck fellowships help ensure that our research is pushing the frontiers of knowledge. Congratulations to the 2016 Cullen-Peck fellows, and thank you for all you do for the Georgia Tech community.”

Tamara Bogdanovic is a theoretical astrophysicist whose research interests include the ins and outs of some of the most massive black holes in the universe. Her group investigates observational signatures associated with supermassive black holes interacting with gas and stars in galactic nuclei.

 Recently her group offered a plausible solution to a puzzle: Why is the center of the Milky Way galaxy full of young stars but has very few old ones? Scientists suspect that remnants of old stars are present but are too faint to be detected by telescopes. The theory is that old stars have been dimmed by repeated collisions with the accretion disk – a disk-like structure of diffuse material – that at some point in the past orbited a supermassive black hole in the center of our galaxy.

Computer simulations using models of red giant stars suggest that such collisions could have inflicted significant damage to old stars, making them invisible, only if the accretion disk was sufficiently dense and massive. The study, published in The Astrophysical Journal, is the first to run computer simulations on the theory, which was introduced in 2014.

“The generous support of the Cullen-Peck fellowship will allow us to foray into unexplored aspects of the interaction of matter and radiation in the deep gravitational wells of black holes,” Bogdanovic says. She hopes to be able to make more accurate theoretical predictions about the signatures of accreting supermassive black holes in distant galaxies, which can be confirmed by observations.

Trained as a geophysicist, Andrew V. Newman studies the active deformation and failure of Earth's rigid outer layer in areas of frequent seismic and volcanic activity. And he wants to understand their impact on society.

Of particular interest are megathrust faults, which are responsible for the largest, and some of the deadliest, earthquakes. For example, using a small network of seismometers and Global Positioning System (GPS) sensors, Newman’s team mapped a segment of a megathrust fault in Costa Rica that was locked, loaded, and ready for failure. They reported the discovery in the Journal of Geophysical Research  in June 2012. Three months later, the earthquake occurred. 

Newman’s group again measured the GPS sites and reported in Nature Geoscience that the anticipated earthquake occurred directly in the locked region and with approximately the magnitude the team estimated was possible. Such pre-event imaging and discovery of dangerous megathrust loading is rare because most such earthquakes occur underwater, where GPS doesn’t work. Likewise, these zones are more concerning, because they generate dangerous tsunami waves.  

With the support from the Cullen-Peck fellowship, Newman plans to “explore new and low-cost methodologies for making observations of precise ground deformation on the seafloor.” In the journal Nature, Newman had argued that such tools are needed to explore 90% of the active plate boundaries to both better understand dynamics of tectonic plate interaction and to illuminate the risk associated with their geologic hazards, including tsunami generation and underwater volcanism.

Frank J. Stewart explores the genetic diversity of marine microorganisms in hopes of answering two fundamental questions: How do ecological and evolutionary processes create and structure genetic diversity? How is this genetic diversity linked to the diverse biogeochemical functions of microorganisms in nature? In particular, his group is interested in how oxygen loss affects the diversity and metabolism of marine microbes. 

In early August 2016, Stewart and others reported in the journal Nature the discovery of new bacterial strains that thrive in oxygen-poor parts of the ocean. The new strains breath nitrogen-containing nutrients in place of oxygen. Their metabolism thus helps deplete nitrogen from the oceans, making the oxygen-poor zones even more uninhabitable, as well as kick-starting metabolic processes that generate nitrous oxide, a potent greenhouse gas.

The zinger is that climate change is causing oxygen-poor zones to expand, meaning these new strains will play an increasingly larger role in shaping ocean chemistry. 

Stewart will use the award to advance a project to analyze whole-genome gene expression data (transcriptomes) from single bacterial cells. Single-cell transcriptomics has been used to study eukaryotic cells, he says, but has been difficult when applied to bacterial cells. With collaborators David A. Weitz and Peter R. Girguis, at Harvard University, Stewart is optimizing methods to recover bacterial transcriptomes from single cells.

If the method works, Stewart says, “it could enhance understanding of microbial ecology and diversity in all of the environments our lab studies, including those in the open ocean and those in the guts of animals.” 

Research in the laboratory of  Lewis A. Wheaton aims to understand how healthy people plan and execute complex tasks, such as kicking a ball or using tools. At present, he is focused on understanding motor skill development across many populations and the neurophysiological relationships between motor development and lexical (vocabulary) development in pediatric populations. The goal is to reveal couplings of language and motor imitation.  

Another focus area is motor skill development after traumatic amputation. Wheaton would like to understand how central neural networks for motor learning are affected after amputation and what role they play in the use of prostheses.

The award will help set up new human neuroimaging studies to identify functional and neuroanatomical changes related to motor learning, Wheaton says. “It will also partially fund a student who is expanding this work to develop better therapeutic approaches for patients with neurological injury and disease.”  

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