Eric Sembrat's Test Bonanza

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

Aug 23, 2016 | Atlanta, GA

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 Franklin H. “Frank” Cullen (B.S. in Mathematics with Honors 1973, M.S. in Operations Research 1975, Ph.D. Engineering 1984) and Elizabeth “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.” 

School of Earth and Atmospheric Sciences' Joseph Dufek,School of Physics' Deirdre Shoemaker, and School of Psychology's Jenny Singleton have been selected to be part of the first cohort of Georgia Tech's Emerging Leaders Program. They join 13 others from across Georgia Tech in a nine-month program that includes workshops, group work, self-assessments and 360-degree assessments. Read more at http://www.provost.gatech.edu/updates/inaugural-emerging-leadership-deve....

Georgia Tech’s partnership with the Oak Ridge National Laboratory (ORNL) continues to grow. The latest engagement is the early June visit of undergraduates doing research with Georgia Tech professors this summer.

Ten physics undergraduates doing research in the School of Physics traveled to Tennessee to see for themselves the cutting-edge research taking place at ORNL, which is a strategic research partner of Georgia Tech. They met ORNL scientists, who described their research and the national laboratory’s unique facilities, such as the High Flux Isotope Reactor, the Spallation Neutron Source Facility, and the Titan supercomputer.

A special treat was the opportunity to meet with James B. Roberto, a scientist who was part of the ORNL team that discovered element 117, along with teams from Russia and the Lawrence Livermore National Laboratory, in California. ORNL received the privilege of naming element 117 tennessine (Ts), after the state of Tennessee.

The 10 students who visited ORNL are taking part in the National Science Foundation’s Research Experiences for Undergraduates (REU) Program “Broadening Participation in Undergraduate Research in Physics.” Just established in 2016, the program enables undergrads to conduct research in one of the  program partner schools: Clark Atlanta University, Georgia Tech, Morehouse College, and Spelman College.

During the 10-week summer program, the physics majors, who came from various parts of the country, will conduct research with Georgia Tech physicists and participate in professional development activities, faculty seminars, and a research symposium. One of the program’s goals is to deepen the research experience and knowledge of high-achievement students from groups that have historically been underrepresented in physics and thereby increase the probability that they continue to graduate school.

The 10 participants, their home institutions, and their Georgia Tech research supervisors are as follows:

Frank Adams, Clark Atlanta University; with Simon N. Sponberg, whose research interests include neuromechanics, locomotor control, and computational neuroscience.

Andrew Blount, Pennsylvania State University; with Colin V. Parker, whose research interests are experimental ultracold atoms, quantum simulation, and condensed matter.

Kelimar Diaz Cruz, University of Puerto Rico, Rio Piedras, and Nathan Hines, Morehouse College; with Daniel I. Goldman, who studies the mechanics of locomotion of organisms and robots.

Eliza Gazda, Embry Riddle Aeronautical University; with A. Nepomuk Otte, whose research interests are astroparticle physics, instrumentation, and photon detectors.

Peter Lott, Howard University; with Ignacio Taboada; who studies neutrinos and gamma rays to find the sources of cosmic rays.

Hannahmariam Mekbib, North Carolina State University;  with Alberto Fernandez-Nieves; whose research on the physics of soft materials focuses on the connection between microscopic order and macroscopic properties.

Shawn Sanderlin, Georgia Gwinnett College; with Peter J. Yunker, who studies colloids, disordered solids, hierarchical structures, self- and directed-assembly of proteins, and fluid-fluid interfaces.

Donavan White, Morehouse College; with Harold D. Kim, who studies the biophysics of the genome.

William Wills, Georgia Gwinnett College; with Deirdre M. Shoemaker, whose work focuses on numerical relativity and its interface with gravitational wave astronomy.

Accompanying the students were School of Physics’ REU coordinator, Shaun Ashley; Martin Mourigal, who organized the Georgia Tech visit; and College of Sciences Director of Academic Diversity Keith L. Oden.

Also with the group but not part of the REU program was Maximilian Stumvoll. He is a physics undergraduate studying in the University of Glasgow who is doing summer research in the lab of James C. Gumbart.

The Georgia Tech contingent gratefully acknowledged the efforts of their ORNL counterparts: Ian S. Anderson, Brittany M. Beitz, and Barbara H. Penland.

When early terrestrial animals began moving about on mud and sand 360 million years ago, the powerful tails they used as fish may have been more important than scientists previously realized. That’s one conclusion from a new study of African mudskipper fish and a robot modeled on the animal.

Animals analogous to the mudskipper would have used modified fins to move around on flat surfaces, but for climbing sandy slopes, the animals could have benefitted from using their tails to propel themselves forward, the researchers found. Results of the study, reported July 8 in the journal Science, could help designers create amphibious robots able to move across granular surfaces more efficiently – and with less likelihood of getting stuck in the mud.

Sponsored by the National Science Foundation, the Army Research Office and the Army Research Laboratory, the project involved a multidisciplinary team of physicists, biologists and roboticists from the Georgia Institute of Technology, Clemson University and Carnegie Mellon University. In addition to a detailed study of the mudskipper and development of a robot model that used the animal’s locomotion techniques, the study also examined flow and drag conditions in representative granular materials, and applied a mathematical model incorporating new physics based on the drag research.

“Most robots have trouble moving on terrain that includes sandy slopes,” said Dan Goldman, an associate professor in the Georgia Tech School of Physics. “We noted that not only did the mudskippers use their limbs to propel themselves in a kind of crutching motion on sand and sandy slopes, but that when the going got tough, they used their tails in concert with limb propulsion to ascend a slope. Our robot model was only able to climb sandy slopes when it similarly used its tail in coordination with its appendages.”

Based on fossil records, scientists have long studied how early land animals may have gotten around, and the new study suggests their tails – which played a key role in swimming as fish – may have helped supplement the work of fins, especially on sloping granular surfaces such as beaches and mudflats.

“We were interested in examining one of the most important evolutionary events in our history as animals: the transition from living in water to living on land,” said Richard Blob, alumni distinguished professor of biological sciences at Clemson University. “Because of the focus on limbs, the role of the tail may not have been considered very strongly in the past. In some ways, it was hiding in plain sight. Some of the features that the animals used were new, such as limbs, but some of them were existing features that they simply co-opted to allow them to move into a new habitat.”

With Ph.D. student Sandy Kawano, now a researcher at the National Institute for  Mathematical and Biological Synthesis, Blob’s lab recorded how the mudskippers (Periopthalmus barbaratus) moved on a variety of loose surfaces, providing data and video to Goldman’s laboratory. The small fish, which uses its front fins and tail to move on land, lives in tidal areas near shore, spending time in the water and on sandy and muddy surfaces.

Benjamin McInroe was a Georgia Tech undergraduate when he analyzed the mudskipper data provided by the Clemson team. He applied the principles to a robot model known as MuddyBot that has two limbs and a powerful tail, with motion provided by electric motors. Information from both the mudskipper and robotic studies were also factored into a mathematical model provided by researchers at Carnegie Mellon University.

“We used three complementary approaches,” said McInroe, who is a now a Ph.D. student at the University of California Berkeley. “The fish provided a morphological, functional model of these early walkers. With the robot, we are able to simplify the complexity of the mudskipper and by varying the parameters, understand the physical mechanisms of what was happening. With the mathematical model and its simulations, we were able to understand the physics behind what was going on.”

Both the mudskippers and the robot moved by lifting themselves up to reduce drag on their bodies, and both needed a kick from their tails to climb 20-degree sandy slopes. Using their “fins” alone, both struggled to climb slopes and often slid backward if they didn’t use their tails, McInroe noted. Early land animals likely didn’t have precise control over their limbs, and the tail may have compensated for that limitation, helping the animals ascend sandy slopes.

The Carnegie Mellon University researchers, who have worked with Goldman on relating the locomotion of other animals to robots, demonstrated that theoretical models developed to describe the complex motion of robots can also be used to understand locomotion in the natural world.

“Our computer modeling tools allow us to visualize, and therefore better understand, how the mudskipper incorporates its tail and flipper motions to locomote,” said Howie Choset, a professor in the Robotics Institute at Carnegie Mellon University. “This work also will advance robotics in those cases where a robot needs to surmount challenging terrains with various inclinations.”

The model was based on a framework proposed to broadly understand locomotion by physicist Frank Wilczek – a Nobel Prize winner – and his then student Alfred Shapere in the 1980s. The so-called “geometric mechanics” approach to locomotion of human-made devices (like satellites) was largely developed by engineers, including those in Choset’s group. To provide force relationships as inputs to the mudskipper robot model, Georgia Tech postdoctoral fellow Jennifer Rieser and Georgia Tech graduate student Perrin Schiebel measured drag in inclined granular materials.

Information from the study could help in the design of robots that may need to move on surfaces such as sand that flows around limbs, said Goldman. Such flow of the substrate can impede motion, depending on the shape of the appendage entering the sand and the type of motion.

But the study’s most significant impact may be to provide new insights into how vertebrates made the transition from water to land.

“We want to ultimately know how natural selection can act to modify structures already present in organisms to allow for locomotion in a fundamentally different environment,” Goldman said. “Swimming and walking on land are fundamentally different, yet these early animals had to make the transition.”

The project also represents a combination of physics, biology and engineering.

“Professor Goldman and his collaborators are combining physics and engineering prototyping approaches to understand the physical principles that allow animals to move in different environments,” said Krastan Blagoev, program director in the National Science Foundation’s Division of Physics. “This novel approach to living organisms promises to bring to biological sciences higher predictive power and at the same time uncover engineering principles that we have never imagined before.”

In addition to those already mentioned, the project also included co-first author Henry Astley, a Georgia Tech postdoctoral researcher when the project was done, and Chaohui Gong, a postdoctoral researcher at Carnegie Mellon University.

This research was supported by the National Science Foundation and the NSF Physics of Living Systems program through grants PHY-1205878, PHY-1150760, CMMI-1361778; the Army Research Office through grant W911NF-11-1-0514, and the Army Research Laboratory MAST CTA program. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation, the Army Research Office or the Army Research Laboratory. The Robotics Collaborative Technology Alliance also supported this work.

CITATION: Benjamin McInroe, et al., “Tail use improves soft substrate performance in models of early vertebrate land locomotors,” (Science, 2016).

Research News
Georgia Institute of Technology
177 North Avenue
Atlanta, Georgia 30332-0181 USA

Media Contacts: John Toon (404-894-6986) (jtoon@gatech.edu) or Ben Brumfield (404-385-1933) (ben.brumfield@comm.gatech.edu).

Writer: John Toon

Simon N. Sponberg, an assistant professor in the School of Physics, is the sixth College of Sciences CAREER awardee. Sponberg, who has a partial appointment in the School of Applied Physiology, is interested in animal locomotion. His lab studies how the versatile, agile movements of animals arise from their physiological components, from the perspectives of physics and comparative biology. 

“I’m thrilled – but not at all surprised – by the recognition of accomplishment and promise by our early-career colleagues that these NSF CAREER awards signal. Their successes reflect the vigor they bring to their respective schools and to mathematics and the sciences at Georgia Tech,” says College of Sciences Dean Paul M. Goldbart.

The CAREER awards are NSF’s most prestigious grant to support junior faculty who exemplify the role of teacher-scholars. Through five years of sustained support, the award enables promising and talented researchers to build a foundation for a lifetime of leadership in integrating education and research.