December 31, 1969 |

What can microorganisms teach us about climate change?

Plenty, because microbes respond, adapt, and evolve faster than other organisms. Scientists can discover how microorganisms will change because of global warming more quickly than is possible for complex organisms. Understanding how microbes respond to climate change will help predict its effects on other forms of life, including humans.

Yet our understanding of microbes’ complex functions in ecosystems and their interaction with a warming planet is incomplete. Filling the knowledge gaps is crucial, says a  report just released by the American Academy of Microbiology and the American Geophysical Union. The report, based on a workshop of experts, underscores the importance of microbes in ecosystems buffeted by climate change and identifies priorities for future study.

In addressing climate change, it’s important to understand the importance of microbes in ecosystems, says Joel E. Kostka, a professor in the School of Biological Sciences and the School of Earth and Atmospheric Sciences. He was invited to the workshop for his expertise on microbes in terrestrial polar environments. Despite their size, microorganisms provide critical services to ecosystems, Kostka says. “Through activities that produce or consume greenhouse gases, microbes intimately impact Earth’s climate.”

Microbes are the decomposers, breaking down organic matter and recycling nutrients, Kostka says. “Literally, the clean air we breathe and the food we eat depend upon carbon and nutrient cycling – ecosystem services provided by microbes.” 

However, the processes microbes mediate are complex and need to be better understood, Kostka says, “so we can make accurate predictions of how ecosystems will respond to climate change.”  

One example of that complexity is plant-microbe interactions. Thousands of microbial species make up plant microbiomes – microbes that live inside or on plants.  Microbiomes help plants grow better through nutrient acquisition among many functions. Conversely, microbes process organic matter produced by plants.  How microbial communities will change due to Earth’s warming will depend on how plants respond and vice versa, Kostka says. To understand the effect of climate change on ecosystems, we have to know how plants and microbiomes interact or communicate.

Also highlighted by the workshop, Kostka says, is the need for communication across scientific disciplines.  “I found myself informing the chemists on the latest information we have on microbes and microbial activity in wetlands, for example.”

The report is intended for the public, educators, and the broader science community, Kostka says. “I would hope that it represents a call to action for better understanding of microbiomes in the environment.”

 

Massive landslides, similar to those found on Earth, are occurring on the asteroid Ceres. That’s according to a new study led by the Georgia Institute of Technology, adding to the growing evidence that Ceres retains a significant amount of water ice.

The study is published in the journal Nature Geoscience. It used data from NASA’s Dawn spacecraft to identify three different types of landslides, or flow features, on the Texas-sized asteroid.

Type I are relatively round, large and have thick "toes" at their ends. They look similar to rock glaciers and icy landslides in Earth’s arctic. Type I landslides are mostly found at high latitudes, which is also where the most ice is thought to reside near Ceres' surface.

Type II features are the most common of Ceres’ landslides and look similar to deposits left by avalanches on Earth. They are thinner and longer than Type I and found at mid-latitudes. The authors affectionately call one such Type II landslide "Bart" because of its resemblance to the elongated head of Bart Simpson from TV's "The Simpsons."

Ceres' Type III features appear to form when some of the ice is melted during impact events. These landslides at low latitudes are always found coming from large-impact craters.

Georgia Tech Assistant Professor and Dawn Science Team Associate Britney Schmidt led the study. She believes it provides more proof that the asteroid’s shallow subsurface is a mixture of rock and ice.

“Landslides cover more area in the poles than at the equator, but most surface processes generally don’t care about latitude,” said Schmidt, a faculty member in the School of Earth and Atmospheric Sciences. “That’s one reason why we think it’s ice affecting the flow processes. There’s no other good way to explain why the poles have huge, thick landslides; mid-latitudes have a mixture of sheeted and thick landslides; and low latitudes have just a few.”  

The study’s researchers were surprised at just how many landslides Ceres has in general. About 20 percent to 30 percent of craters greater than 6 miles (10 kilometers) wide have some type of landslide associated with them. Such widespread features formed by "ground ice" processes, made possible because of a mixture of rock and ice, have only been observed before on Earth and Mars.

Based on the shape and distribution of landslides on Ceres, the authors estimate that the upper layers of Ceres may range from 10 percent to 50 percent ice by volume.

“These landslides offer us the opportunity to understand what’s happening in the upper few kilometers of Ceres,” said Georgia Tech Ph.D. student Heather Chilton, a co-author on the paper. “That’s a sweet spot between information about the upper meter or so provided by the GRaND (Gamma Ray and Neutron Detector (GRaND) and VIR (Visible and Infrared Spectrometer) instrument data, and the tens of kilometers-deep structure elucidated by crater studies.”

"It’s just kind of fun that we see features on this small planet that remind us of those on the big planets, like Earth and Mars,” Schmidt said. “It seems more and more that Ceres is our innermost icy world.”

The Dawn mission is managed by NASA’s Jet Propulsion Laboratory for NASA's Science Mission Directorate in Washington, D.C. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit: http://dawn.jpl.nasa.gov/mission.

Co-written by Elizabeth Landau, Jet Propulsion Lab

Event Details

Date/Time:

December 31, 1969 |

Massive landslides, similar to those found on Earth, are occurring on the asteroid Ceres. That’s according to a new study led by the Georgia Institute of Technology, adding to the growing evidence that Ceres retains a significant amount of water ice.

The study is published in the journal Nature Geoscience. It used data from NASA’s Dawn spacecraft to identify three different types of landslides, or flow features, on the Texas-sized asteroid.

Type I are relatively round, large and have thick "toes" at their ends. They look similar to rock glaciers and icy landslides in Earth’s arctic. Type I landslides are mostly found at high latitudes, which is also where the most ice is thought to reside near Ceres' surface.

Type II features are the most common of Ceres’ landslides and look similar to deposits left by avalanches on Earth. They are thinner and longer than Type I and found at mid-latitudes. The authors affectionately call one such Type II landslide "Bart" because of its resemblance to the elongated head of Bart Simpson from TV's "The Simpsons."

Ceres' Type III features appear to form when some of the ice is melted during impact events. These landslides at low latitudes are always found coming from large-impact craters.

Georgia Tech Assistant Professor and Dawn Science Team Associate Britney Schmidt led the study. She believes it provides more proof that the asteroid’s shallow subsurface is a mixture of rock and ice.

“Landslides cover more area in the poles than at the equator, but most surface processes generally don’t care about latitude,” said Schmidt, a faculty member in the School of Earth and Atmospheric Sciences. “That’s one reason why we think it’s ice affecting the flow processes. There’s no other good way to explain why the poles have huge, thick landslides; mid-latitudes have a mixture of sheeted and thick landslides; and low latitudes have just a few.”  

The study’s researchers were surprised at just how many landslides Ceres has in general. About 20 percent to 30 percent of craters greater than 6 miles (10 kilometers) wide have some type of landslide associated with them. Such widespread features formed by "ground ice" processes, made possible because of a mixture of rock and ice, have only been observed before on Earth and Mars.

Based on the shape and distribution of landslides on Ceres, the authors estimate that the upper layers of Ceres may range from 10 percent to 50 percent ice by volume.

“These landslides offer us the opportunity to understand what’s happening in the upper few kilometers of Ceres,” said Georgia Tech Ph.D. student Heather Chilton, a co-author on the paper. “That’s a sweet spot between information about the upper meter or so provided by the GRaND (Gamma Ray and Neutron Detector (GRaND) and VIR (Visible and Infrared Spectrometer) instrument data, and the tens of kilometers-deep structure elucidated by crater studies.”

"It’s just kind of fun that we see features on this small planet that remind us of those on the big planets, like Earth and Mars,” Schmidt said. “It seems more and more that Ceres is our innermost icy world.”

The Dawn mission is managed by NASA’s Jet Propulsion Laboratory for NASA's Science Mission Directorate in Washington, D.C. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit: http://dawn.jpl.nasa.gov/mission.

Co-written by Elizabeth Landau, Jet Propulsion Lab

December 31, 1969 |

Honeybees have almost three million hairs on their tiny bodies. Each hair is strategically placed to carry pollen and also to brush it off. Researchers at Georgia Tech used high-speed footage of tethered bees covered in pollen to see how these hairs work. David Hu, an assistant professor in the School of Biological Sciences, was a co-author of the study. The Georgia Tech Urban Honey Bee Project assisted in the research. 

December 31, 1969 |

Raquel L. Lieberman is the recipient of the 2017 Georgia Tech Sigma Xi Best Faculty Paper Award. Lieberman is an associate professor in the School of Chemistry and Biochemistry. The paper recognized by this award is “Enzymatic hydrolysis by transition-metal-dependent nucleophilic aromatic substitution,” published in Nature Chemical Biology.

The work involves protein crystallography, enzymology, and organic chemistry to address a question related to chemical ecology. This diversity of fields exemplifies the highly interdisciplinary questions Georgia Tech researchers are aiming to answer.

Also notable is the diversity of Lieberman’s research team. It involved high school, undergraduate, and graduate students; a technician; and a postdoctoral fellow. Also with the team was a remarkable high school teacher whose teaching has been transformed by doing research in the Lieberman lab. The paper uniquely embodies Georgia Tech’s motto: Progress and Service.

The paper describes a precedent-setting metalloenzyme discovered in the context of the complex biochemical warfare waged in farm soils where potato is grown. In such soils, the bacterium Streptomyces scabies infects potato tubers and secretes compounds that induce the formation of scabs; among them is 5-nitroanthranilic acid (5NAA).

Also in the same soils is another bacterium, Bradhyrhizobium sp. This nonpathogenic microbe seems to defend itself and the potato plant from S. scabies by detoxifying 5NAA. Lieberman’s collaborator of more than five years, Jim C. Spain, in the School of Civil and Environmental Engineering, discovered the unusual metalloenzyme in this bacterium.

The enzyme – 5-nitroanthranilic acid aminohydrolase (5NAA-A) – performs unusual chemistry: hydrolysis of a nitroaromatic compound. Nitroaromatic compounds are notoriously toxic, challenging to synthesize, and difficult to degrade, but are found widely in synthetic dyes, explosives, and pesticides.

The Lieberman team solved the structure of 5NAA-A and investigated its enzyme mechanism, substrate specificity, metal-binding properties, and phylogeny. They found that the chemistry it mediates, and the mechanism it uses, is rare among known enzymes.

A major force in the work was Casey Bethel, who is Georgia’s 2017 Teacher of the Year (TOTY).  Bethel helped pave the way to solving the crystal structures of 5-NAA-A and mentored students who helped confirm its unique chemical properties.

A highly charismatic high school teacher, Bethel has spent the past six summers working in the Lieberman lab. His participation was made possible by Georgia Intern Fellowships for Teachers (GIFT), a program administered by the Center for Education Integrating Science, Mathematics, and  Computing. Funds from Lieberman’s NSF CAREER award sponsored Bethel for four of the six years.

“It’s rare – we believe unprecedented! – in Georgia for the TOTY award to go to a STEM teacher at the high school level,” Lieberman says.

“On behalf of my co-authors, I thank Sigma Xi and Georgia Tech for this honor,” Lieberman says. “Not only does our discovery have impact from a number of scientific angles; our study also truly epitomizes the interdisciplinary and collaborative culture at Georgia Tech."

December 31, 1969 |

According to a study published by Georgia Tech researchers in the journal Scientific Reports, healthy people who take measures to avoid getting sick cannot fully eradicate the spread of disease without an infected individual taking preemptive steps first. Instead, the sick individual in question needs to take steps to avoid infecting anyone else, and the main motivator for taking those steps seems to be empathy -- the ability to understand the feelings of others. Ceyhun Eksin and Joshua S. Weitz collaborated on the study with a researcher from King Abdullah University of Science and Technology.  Eksin is a postdoctorate fellow in Weitz's lab in the School of Biological Sciences. 

Experiments led by researchers at the Georgia Institute of Technology suggest the particles that cover the surface of Saturn’s largest moon, Titan, are “electrically charged.” When the wind blows hard enough (approximately 15 mph), Titan’s non-silicate granules get kicked up and start to hop in a motion referred to as saltation. As they collide, they become frictionally charged, like a balloon rubbing against your hair, and clump together in a way not observed for sand dune grains on Earth — they become resistant to further motion. They maintain that charge for days or months at a time and attach to other hydrocarbon substances, much like packing peanuts used in shipping boxes here on Earth.

The findings have just been published in the journal Nature Geoscience.

“If you grabbed piles of grains and built a sand castle on Titan, it would perhaps stay together for weeks due to their electrostatic properties,” said Josef Dufek, the Georgia Tech professor who co-led the study. “Any spacecraft that lands in regions of granular material on Titan is going to have a tough time staying clean. Think of putting a cat in a box of packing peanuts.”

The electrification findings may help explain an odd phenomenon. Prevailing winds on Titan blow from east to west across the moon’s surface, but sandy dunes nearly 300 feet tall seem to form in the opposite direction.

“These electrostatic forces increase frictional thresholds,” said Josh Méndez Harper, a Georgia Tech geophysics and electrical engineering doctoral student who is the paper’s lead author. “This makes the grains so sticky and cohesive that only heavy winds can move them. The prevailing winds aren’t strong enough to shape the dunes.”

To test particle flow under Titan-like conditions, the researchers built a small experiment in a modified pressure vessel in their Georgia Tech lab. They inserted grains of naphthalene and biphenyl — two toxic, carbon and hydrogen bearing compounds believed to exist on Titan’s surface — into a small cylinder. Then they rotated the tube for 20 minutes in a dry, pure nitrogen environment (Titan’s atmosphere is composed of 98 percent nitrogen). Afterwards, they measured the electric properties of each grain as it tumbled out of the tube.

“All of the particles charged well, and about 2 to 5 percent didn’t come out of the tumbler,” said Méndez Harper. “They clung to the inside and stuck together. When we did the same experiment with sand and volcanic ash using Earth-like conditions, all of it came out. Nothing stuck.”

Earth sand does pick up electrical charge when it’s moved, but the charges are smaller and dissipate quickly. That’s one reason why you need water to keep sand together when building a sand castle. Not so with Titan.

“These non-silicate, granular materials can hold their electrostatic charges for days, weeks or months at a time under low-gravity conditions,” said George McDonald, a graduate student in the School of Earth and Atmospheric Sciences who also co-authored the paper.

Visually, Titan is the object in the solar system most like Earth. Data gathered from multiple flybys by Cassini since 2005 have revealed large liquid lakes at the poles, as well as mountains, rivers and potentially volcanoes. However, instead of water-filled oceans and seas, they’re composed of methane and ethane and are replenished by precipitation from hydrocarbon-filled clouds. Titan’s surface pressure is a bit higher than our planet — standing on the moon would feel similar to standing 15 feet underwater here on Earth.

“Titan’s extreme physical environment requires scientists to think differently about what we’ve learned of Earth’s granular dynamics,” said Dufek. “Landforms are influenced by forces that aren’t intuitive to us because those forces aren’t so important on Earth. Titan is a strange, electrostatically sticky world.”

Researchers from the Jet Propulsion Lab, University of Tennessee-Knoxville and Cornell University also co-authored the paper, which is titled “Electrification of Sand on Titan and its Influence on Sediment Transport.”

The study is partially supported by the National Science Foundation (EAR-1150794). Méndez Harper held a National Science Foundation graduate fellowship while conducting the study. McDonald has a National Defense Science and Engineering Graduate Fellowship. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsors.

Event Details

Date/Time:

December 31, 1969 |

Experiments led by researchers at the Georgia Institute of Technology suggest the particles that cover the surface of Saturn’s largest moon, Titan, are “electrically charged.” When the wind blows hard enough (approximately 15 mph), Titan’s non-silicate granules get kicked up and start to hop in a motion referred to as saltation. As they collide, they become frictionally charged, like a balloon rubbing against your hair, and clump together in a way not observed for sand dune grains on Earth — they become resistant to further motion. They maintain that charge for days or months at a time and attach to other hydrocarbon substances, much like packing peanuts used in shipping boxes here on Earth.

The findings have just been published in the journal Nature Geoscience.

“If you grabbed piles of grains and built a sand castle on Titan, it would perhaps stay together for weeks due to their electrostatic properties,” said Josef Dufek, the Georgia Tech professor who co-led the study. “Any spacecraft that lands in regions of granular material on Titan is going to have a tough time staying clean. Think of putting a cat in a box of packing peanuts.”

The electrification findings may help explain an odd phenomenon. Prevailing winds on Titan blow from east to west across the moon’s surface, but sandy dunes nearly 300 feet tall seem to form in the opposite direction.

“These electrostatic forces increase frictional thresholds,” said Josh Méndez Harper, a Georgia Tech geophysics and electrical engineering doctoral student who is the paper’s lead author. “This makes the grains so sticky and cohesive that only heavy winds can move them. The prevailing winds aren’t strong enough to shape the dunes.”

To test particle flow under Titan-like conditions, the researchers built a small experiment in a modified pressure vessel in their Georgia Tech lab. They inserted grains of naphthalene and biphenyl — two toxic, carbon and hydrogen bearing compounds believed to exist on Titan’s surface — into a small cylinder. Then they rotated the tube for 20 minutes in a dry, pure nitrogen environment (Titan’s atmosphere is composed of 98 percent nitrogen). Afterwards, they measured the electric properties of each grain as it tumbled out of the tube.

“All of the particles charged well, and about 2 to 5 percent didn’t come out of the tumbler,” said Méndez Harper. “They clung to the inside and stuck together. When we did the same experiment with sand and volcanic ash using Earth-like conditions, all of it came out. Nothing stuck.”

Earth sand does pick up electrical charge when it’s moved, but the charges are smaller and dissipate quickly. That’s one reason why you need water to keep sand together when building a sand castle. Not so with Titan.

“These non-silicate, granular materials can hold their electrostatic charges for days, weeks or months at a time under low-gravity conditions,” said George McDonald, a graduate student in the School of Earth and Atmospheric Sciences who also co-authored the paper.

Visually, Titan is the object in the solar system most like Earth. Data gathered from multiple flybys by Cassini since 2005 have revealed large liquid lakes at the poles, as well as mountains, rivers and potentially volcanoes. However, instead of water-filled oceans and seas, they’re composed of methane and ethane and are replenished by precipitation from hydrocarbon-filled clouds. Titan’s surface pressure is a bit higher than our planet — standing on the moon would feel similar to standing 15 feet underwater here on Earth.

“Titan’s extreme physical environment requires scientists to think differently about what we’ve learned of Earth’s granular dynamics,” said Dufek. “Landforms are influenced by forces that aren’t intuitive to us because those forces aren’t so important on Earth. Titan is a strange, electrostatically sticky world.”

Researchers from the Jet Propulsion Lab, University of Tennessee-Knoxville and Cornell University also co-authored the paper, which is titled “Electrification of Sand on Titan and its Influence on Sediment Transport.”

The study is partially supported by the National Science Foundation (EAR-1150794). Méndez Harper held a National Science Foundation graduate fellowship while conducting the study. McDonald has a National Defense Science and Engineering Graduate Fellowship. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsors.

December 31, 1969 |

Negotiating uneven ground can be challenging for people who use lower-limb prostheses to walk, so researchers spend time searching for solutions that will allow greater stability in these situations. Manufacturers of prosthetic feet have contributed to a solution by adding multiaxial features that better reproduce the behavior of human ankles, which can stiffen as the terrain warrants. However, School of Biological Sciences Senior Lecturer W. Lee Childers found that there was a lack of evidence evaluating the prosthetic ankle stiffness as it relates to the user’s dynamic balance and gait over uneven terrain. Thus, his continuing research focuses on defining the effect of multiaxial stiffness on gait stability among people with unilateral transtibial amputations....“The main focus of this work was to justify that it is a good thing for prosthetic feet to have multiaxial function,” Childers says, because if it can prevent falls among its users, its value is demonstrated to the payers.

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