A new study demonstrates the physics that elephants use to feed themselves the massive quantities of leaves, fruit and roots needed to sustain their multi-ton bodies. 

A human can pick up multiple objects at once by squeezing them together with both hands and arms. An African elephant also picks up many items at once but with only one appendage—its soft, heavy trunk. How the elephant solves this challenge could provide inspiration for future robotics. 

A wild African elephant eats rapidly, consuming 190 grams of food a minute, to provide adequate fuel for its vast bulk. “Elephants are in a rush when they are eating,” said David L. Hu, associate professor in the School of Mechanical Engineering and the School of Biology at the Georgia Institute of Technology. The elephant diet consists of large volumes of plant materials such as leaves, fruit and roots. To eat these, elephants sweep loose items into a pile and crush them into a manageable solid that can be picked up by the trunk. 

“They don’t just use the trunk’s strong muscles to squeeze the plants together,” said Hu. “The elephants also use the weight of the trunk, and they do that by forming a joint in the trunk. The trunk below the joint becomes a stiff pillar that applies weight to the pile of plant materials.” 

About 30 percent of the applied force is derived from the pillar’s weight alone, and about 70 percent from exerting muscular effort, according to a new study published in the Journal of the Royal Society Interface by Hu and colleagues at Georgia Tech, the Rochester Institute of Technology and Zoo Atlanta. 

The African elephant can raise or lower the trunk joint’s height by up to 11 centimeters to increase or reduce the applied force. “When elephants need more force, the joint is higher up on the trunk,” Hu said. Elephant trunks weigh about 150 kilograms and have 40,000 muscles. “The huge number of muscles in the trunk allows the elephant great freedom for where it puts this joint.”

Hu and his colleagues studied a 34-year-old female African elephant (Loxodonta africana) over several weeks in the summer of 2017. All experiments were supervised by the staff at Zoo Atlanta. Food was arranged by hand into a pile in the center of a force plate to measure how much force the animal generated. 

The elephant’s trunk is similar to other boneless organs in nature such as the octopus’s arm and the human tongue. But unlike an octopus’s arm, an elephant’s trunk is heavy enough to provide significant force on an object without muscular pressure. This is the first study to show that an animal can use the weight of its own appendage to help apply force and the first with a live elephant to understand forces that it can apply to materials. 

Using mathematical models, the researchers found that the greater the number of objects to be squeezed and picked up, the greater the force that must be applied. 

“Picking up two objects requires very little force to press them together, while picking up 40,000 objects requires a lot of force,” Hu said. This principle was tested experimentally with the live elephant by presenting multiple food items varying in number from four to 40,000 in number. The experiments showed that the elephant could vary forces applied with its trunk by a factor of four depending on the number of food items to be picked up.

This research could have applications in robotics, where heavier machines would appear to have few advantages over smaller ones. But, in the future, heavy robotic manipulators could be designed with several adjustable joints that use the device’s own weight to provide adjustable pressure and save energy. There are currently no commercial robots designed to apply their own weight to objects, Hu noted. 

“You could have future robots with several joints, which could apply various weight pressures below joints to help compress objects together for lifting them efficiently,” said Hu. “This would allow you to use the weight of the joints themselves to provide force instead of relying on batteries and extra motors to apply these forces, and that would mean using less energy. For instance, you could have a heavy robot with four joints, and by bending the top joint, the weight below it could apply a load. If you wanted to provide less weight pressure, you could instead bend the second-from-the-top joint. This study shows that there are some advantages for robots in being big and heavy.”

African elephants like the ones in this study have two muscular extensions at the tip of their trunk resembling a pair of fingers that also could be studied as models for future robotics. It’s not well known that elephants have such projections, and this understanding could inform work that is already underway. “The elephant’s technique with these extensions might be used to develop soft robotic grippers that can pick up delicate items such as fruit without damaging them,” Hu noted.

This work was supported by the U.S. Army Research Laboratory and the U.S. Army Research Office Mechanical Sciences Division, Complex Dynamics and Systems Program, under contract W911NF-12-R-0011.

CITATION: Jianing Wu, et al., “Elephant trunks form joints to squeeze together small objects,” (Journal of the Royal Society Interface 15, 2018) http://dx.doi.org/10.1098/rsif.2018.0377

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Episode 7 of ScienceMatters' Season 1 stars Jennifer Leavey.  Listen to the podcast here and read the transcript here.

Jennifer Leavey is a principal academic professional in the School of Biological Science. She also serves College of Sciences as the coordinator of the  Integrated Science Curriculum and director of Georgia Tech Urban Honeybee Project.

The Georgia Tech Urban Honey Bee Project is an interdisciplinary educational initiative to recruit and retain students in STEM careers through the study of how urban habitats affect honey bee health and how technology can be used to study bees. 

Leavey is also the faculty director of the Science and Math Research Training (SMaRT) and Scientific Health and Related Professions (SHaRP) Living Learning Communities of the College of Sciences.These communities aim to create lasting connections among College of Sciences majors who are interested in research (SMaRT) or intend to pursue additional education and training health-rleated fields. 

In Episode 7 of ScienceMatters, Leavey shares her long-lasting passion for both science and rock music. By day, she’s an academic professional; but when she straps on a guitar , she mutates to Leucine Zipper, leader of the rock band Zinc Fingers.

For a change of pace, ScienceMatters samples the band’s science-inspired songs. Leavey shares how the band uses music and other media to make science concepts fun and accessible.  

Take a listen at sciencematters.gatech.edu.

Enter to win a prize by answering the question for Episode 7: 

In episode 7, what is the name of the song that Jennifer Leavey says sounds like a love song but is actually about bacteria living together in biofilms?

Submit your entry by 11 AM on Monday, Oct. 8, at sciencematters.gatech.edu. Answer and winner will be announced shortly after the quiz closes.

Jennifer Leavey is the integrated science curriculum coordinator for the College of Sciences. She also directs the Georgia Tech Urban Honey Bee Project, an interdisciplinary initiative designed to recruit and retain STEM students by studying how urban habitats affect honey bee health and how technology can be used to study bees. 

“Most of the programs I work on relate to encouraging undergraduates to become more engaged in studying science,” Leavey said. “The Georgia Tech Urban Honey Bee Project sprouted out of the idea that if something is authentic, it doesn’t matter what discipline students are in or what class they’re taking, they’ll become interested in it.”

Learn more about Jennifer Leavey's activities, including leading a science rock band, in the full story by Victor Rogers.

Episode 2 of ScienceMatters' Season 1 stars Jenny McGuire. The assistant professor in the School of Earth and Atmospheric Sciences and the School of Biological Sciences has a tough commute to her summer research site: An 80-foot drop into Wyoming’s deep, dark Natural Trap Cave. There she collects fossils that she hopes will yield clues about the impact of climate change on animal and human populations.

Follow her journey at sciencematters.gatech.edu.

Enter to win a prize by answering the episode's question:

What small four-legged animals mentioned in Episode 2 help Jenny McGuire collect bones from Natural Trap Cave?

Submit your entry by noon on Friday, Aug. 31, at sciencematters.gatech.edu. Answer and winner will be announced on Monday, Sept. 3.

Congratulations to Vineeth Aljapur, winner of Episode 1 quiz. Aljapur is a first-year student in the Georgia Tech Bioinformatics Graduate Program.  

Episode 3 of ScienceMatters' Season 1 stars M.G. Finn. Listen to the podcast and read the transcript here!

Leishmaniasis is a scary parasitic disease; it can rot flesh. Formerly contained in countries near the equator, it has arrived in North America. School of Chemistry and Biochemistry Professor and Chair M.G. Finn explains why it’s so tough to fight this disease. His collaboration with Brazilian researcher Alexandre Marques has raised hopes for a possible vaccine.

Follow the the researchers' journey at sciencematters.gatech.edu.

Enter to win a prize by answering the episode's question:

What sugar molecule mentioned in Episode 3 is the main reason surgeons can’t transplant organs from animals into humans?

Submit your entry by noon on Friday, Sept. 7, at sciencematters.gatech.edu. Answer and winner will be announced on Monday, Sept. 10.

Results of Episode 2 Quiz

Q: What small four-legged animals mentioned in Episode 2 help Jenny McGuire collect bones from Natural Trap Cave?

A: Wood rats, pack rats, or rats

The winner is Pedro Marquez Zacarias. He was listening to ScienceMatters while doing routine data analysis for his research.

A third-year Ph.D. student in the Georgia Tech Quantitative Biosciences Graduate Program, Marquez Zacarias aims to add to the understanding of how biological complexity evolved, particularly multicellularity.

Marquez Zacarias comes from a small town in rural México, an indigenous community called Urapicho, in the state of Michoacán.

They may look a little like space capsules, but nuclear magnetic resonance spectrometers stay planted on the floor and use potent magnetism to explore opaque constellations of molecules.

Three Atlanta area universities jointly launched a nuclear magnetic resonance collaboration called the Atlanta NMR Consortium to optimize the use of this technology that provides insights into relevant chemical samples containing so many compounds that they can otherwise easily elude adequate characterization. The consortium has been operating since July 2018.

Crab pee

Take, for example, crab urine. It’s packed with hundreds to thousands of varying metabolites, and researchers at the Georgia Institute of Technology wanted to nail down one or two of them that triggered a widespread crab behavior. Without access to NMR they may not have found them at all even after an extensive search.

The spectrometer pulled the right two needles out of the haystack, so the researchers could test them on the crabs and confirm that they were initiating the behavior.

Emory University, Georgia State University and Georgia Tech already have NMR technology, but the Atlanta NMR Consortium will enable them to fully exploit it while cost-effectively staying on top of upgrades.

“NMR continues to grow and develop because of technological advances,” said David Lynn, a chemistry professor at Emory University.

That means buying new machines every so often, and one new NMR spectrometer can run into the millions; annual maintenance for one machine can cost tens of thousands of dollars. Thus, reducing costs and maximizing usage makes good sense.

Medicine, geochemistry

The human body, sea-side estuaries, and rock strata present huge collections of compounds. NMR takes inventory of complex samples from such sources via the nuclei of atoms in the molecules.

A nucleus has a spin, which makes it magnetic, and NMR spectrometry’s own powerful magnetism detects spins and pinpoints nuclei to feel out whole molecules. These can be large or small, from mineral compounds with three or four component atoms to protein polymers with tens of thousands of parts.

Researchers in medicine, biochemistry, ecology, geology, food science – the possible list is exhaustive -- turn to NMR to untangle their particular molecular jungles. The consortium wants to leverage that diversity.

“As we go in different directions, we will benefit from a cohesive community of people who know how to use NMR for a wide range of problems,” said Anant Paravastu, an associate professor in Georgia Tech’s School of Chemical and Biomolecular Engineering.

“The most important goal for us is the sharing of our expertise,” said Markus Germann, a professor of chemistry at Georgia State.

Consortium members will benefit the most from the pooled NMR resources, but non-partners can also book access. Read more about the Atlanta NMR Consortium here on Georgia Tech’s College of Sciences website

Mention “peat moss,” and many people will conjure up the curly brown plant material that gardeners use. “Oh, the thing you get at Home Depot” – is a common reaction Joel Kostka receives when he mentions that he studies peat moss. His response: “Peat moss is a really cool plant that’s important to the global carbon cycle.”

Joel Kostka is a professor in the School of Biological Sciences and the School of Earth and Atmospheric Sciences at Georgia Tech. The National Science Foundation has just awarded him and three co-principal investigators a $1.15 million, three-year grant to study the microbes in peat moss. The goal is to understand the microbiome’s role in nutrient uptake and the methane dynamics of wetlands and the impact of climate change on these activities.

Kostka’s collaborators are Jennifer Glass, an assistant professor in the Georgia Tech School of Earth and Atmospheric Sciences; Xavier Mayali, a research scientist at Lawrence Livermore National Laboratory; and David Weston, a staff scientist at Oak Ridge National Laboratory.

“It has been shown that microbes that live with peat moss help them to grow better by aiding their uptake of carbon and major nutrients such as nitrogen,” Kostka says. “This project will explore which microbes help to keep peat moss plants healthy, how plants and microbes interact, and how these relationships will be affected by climate change?”

Peat moss, also called Sphagnum, carpets the surface of peatlands. This type of wetland locks up huge amounts of carbon in the form of thick, peat soil deposits. When peat is broken down by microbes, greenhouse gases – methane and carbon dioxide – are produced. Methane is of particular interest, because when released to the atmosphere, it has a warming potential that is 21 times that of carbon dioxide.

Scientists hypothesize that environmental warming could cause peatlands to release a lot more methane, which in turn would accelerate climate change.    

“Our project is fundamental science. We’re trying to figure out how the microbes help the plants grow better.”

Lots of evidence suggest that peatlands will produce more methane as the environment warms up. “Methanogens [methane-producing bacteria] don’t like the cold,” Kostka says. “The warmer it gets, the better they are in producing methane.”

Methane in peatlands bubbles up to the peat moss layer. Methane-consuming microbes in peat moss eat some of the gas released. In effect, microbes in peat moss comprise a biofilter that reduces the amount of methane reaching the atmosphere.

However, “we hypothesize that the methane-eating microbes in peat moss may crash as the climate gets warmer,” Kostka says.  That sets up a double-whammy scenario: As the climate gets warmer, microbes in peatlands produce more methane, while other microbes in peat moss become less able to consume the greenhouse gas. “We could get an explosion of methane much more than we can predict,” Kostka says.   

Information about plant microbiomes is scant. Most plants whose microbiomes are being studied are crops, like corn and soybeans. “Few studies are available on plants that are environmentally important but not so economically important,” Kostka says. “A lot of our work is to build better models for how these wetlands respond to climate change.”

“Few studies are available on plants that are environmentally important but not so economically important. A lot of our work is to build better models for how these wetlands respond to climate change.”

Georgia Tech’s Glass will study the geochemical aspects of the peat moss microbiome. She will measure how fast peat moss microbes fix nitrogen and consume methane. She will also identify the trace nutrients available to peat moss in the wetland.

“Because these peatlands receive most of their nutrient input from precipitation, they contain extremely low concentrations of some bioessential trace metals,” Glass says. “We're interested in testing how trace nutrient availability impacts the growth of methane-cycling microbes exposed to warming temperatures.”

At Lawrence Livermore National Laboratory, Mayali will use NanoSims, an imaging mass spectrometer, to identify what microbes are eating the methane or fixing nitrogen. He will incubate microbe samples with substrates – methane, carbon dioxide, and nitrogen – enriched in rare isotopes such as carbon-13 instead of the normally abundant carbon-12. Analysis by NanoSims creates isotope maps that enables detailed tracing of who did what.

“Our instrument is able to not only track who is eating the methane or fixing nitrogen from the air, but more importantly, how much and where it ultimately ends up, for example into the Sphagnum plant versus being kept by the microbes,” Mayali says.

Meanwhile, at Oak Ridge National Laboratory, Weston will use genetically characterized peat moss and microbial members to construct synthetic communities to test how host moss genes influence microbiome assembly and functioning. “Peat moss microbiomes are extremely complex with thousands of members with diverse metabolic capabilities,” Weston says.

“To help determine the role of specific community member interactions,” Weston adds, “we will decompose the field system into simplified synthetic communities where community changes and nutrients can be accurately measured and subjected to precise environmental manipulations.”

“We can engineer wetlands to encourage the growth of peat moss, but that’s not our goal,” Kostka says. “Our project is fundamental science. We’re trying to figure out how the microbes help the plants grow better.”

Episode 4 of ScienceMatters' Season 1 stars Nastassia Patin. Listen to the podcase here and read the transcript here!

Massive whale sharks headline the Ocean Voyager exhibit at Georgia Aquarium.  Its tiniest residents are the ones that concern Nastassia Patin. Patin is a postdoctoral researcher working in the lab of Frank Stewart. Stewart is an associate professor in the School of Biological Sciences and a member of Georgia Tech's Parker H. Petit Institute for Bioengineering and Bioscience.

Patin's research interests are microbial ecology, environmental microbiology, chemical ecology, metagenomics. Episode 4 describes her findings after studying the microbiome of the Ocean Voyage exhibit at Georgia Aquarium.  What she’s learning may help keep all aquariums clear and healthy.

Take a listen at sciencematters.gatech.edu.

Enter to win a prize by answering the question for Episode 4:

What is the name of the Georgia Aquarium sea turtle mentioned in Episode 4?

Submit your entry by 11 AM on Monday, Sept. 17, at sciencematters.gatech.edu. Answer and winner will be announced shortly after the quiz closes.

Conan Zhao is the winner of ScienceMatters Episode 3 quiz.

ScienceMatters Episode 3 features M.G. Finn, chair of the School of Chemistry and Biochemistry. Finn described his efforts to create a vaccine against the dreadful parasitic disease leishmaniasis.

The quiz question was: What sugar molecule mentioned in Episode 3 is the main reason surgeons can’t transplant organs from animals into humans?

The answer is in the rest of the story, here.

 

Anyone lost in a desert hallucinating mirages knows that extreme dehydration discombobulates the mind. But just two hours of vigorous yard work in the summer sun without drinking fluids could be enough to blunt concentration, according to a new study.

Cognitive functions often wilt as water departs the body, researchers at the Georgia Institute of Technology reported after statistically analyzing data from multiple peer-reviewed research papers on dehydration and cognitive ability. The data pointed to functions like attention, coordination and complex problem solving suffering the most, and activities like reacting quickly when prompted not diminishing much.

“The simplest reaction time tasks were least impacted, even as dehydration got worse, but tasks that require attention were quite impacted,” said Mindy Millard-Stafford, a professor in Georgia Tech’s School of Biological Sciences.

Less fluid, more goofs

As the bodies of test subjects in various studies lost water, the majority of participants increasingly made errors during attention-related tasks that were mostly repetitive and unexciting, such as punching a button in varying patterns for quite a few minutes. There are situations in life that challenge attentiveness in a similar manner, and when it lapses, snafus can happen.

“Maintaining focus in a long meeting, driving a car, a monotonous job in a hot factory that requires you to stay alert are some of them,” said Millard-Stafford, the study’s principal investigator. “Higher-order functions like doing math or applying logic also dropped off.”

The researchers have been concerned that dehydration could raise the risk of an accident, particularly in scenarios that combine heavy sweating and dangerous machinery or military hardware.

Millard-Stafford and first author Matthew Wittbrodt, a former graduate research assistant at Georgia Tech and now a postdoctoral researcher at Emory University, published their meta-analysis of the studies on June 29 in the journal Medicine & Science in Sports & Exercise.

It can happen quickly

There’s no hard and fast rule about when exactly such lapses can pop up, but the researchers examined studies with 1 to 6 percent loss of body mass due to dehydration and found more severe impairments started at 2 percent. That level has been a significant benchmark in related studies.

“There’s already a lot of quantitative documentation that if you lose 2 percent in water it affects physical abilities like muscle endurance or sports tasks and your ability to regulate your body temperature,” said Millard-Stafford, a past president of the American College of Sports Medicine. “We wanted to see if that was similar for cognitive function.”

The researchers looked at 6,591 relevant studies for their comparison, then narrowed them down to 33 papers with scientific criteria and data comparable enough to do metadata analysis. They focused on acute dehydration, which anyone could experience during exertion, heat and/or not drinking as opposed to chronic dehydration, which can be caused by a disease or disorder.

One day to lousy

How much fluid loss adds up to 2 percent body mass loss?

“If you weigh 200 pounds and you go work out for a few of hours, you drop four pounds, and that’s 2 percent body mass,” Millard-Stafford said. And it can happen fast. “With an hour of moderately intense activity, with a temperature in the mid-80s, and moderate humidity, it’s not uncommon to lose a little over 2 pounds of water.”

“If you do 12-hour fluid restriction, nothing by mouth, for medical tests, you’ll go down about 1.5 percent,” she said. “Twenty-four hours fluid restriction takes most people about 3 percent down.”

And that begins to affect more than cognition or athletic abilities and concentration.

“If you drop 4 or 5 percent, you’re going to feel really crummy,” Millard-Stafford said. “Water is the most important nutrient.”

She warned that older people can dry out more easily because they often lose their sensation of thirst and also, their kidneys are less able to concentrate urine, which makes them retain less fluid. People with high body fat content also have lower relative water reserves than lean folks.

Don’t overdo water

Hydration is important, but so is moderation.

“You can have too much water, something called hyponatremia,” Millard-Stafford said. “Some people overly aggressively, out of a fear of dehydration, drink so much water that they dilute their blood and their brain swells.”

This leads to death in rare, extreme cases, for example, when long-distance runners constantly drink but don’t sweat much and end up massively overhydrating.

“Water needs to be enough, just right,” Millard-Stafford said.

Also, she warned that while salt avoidance may be good for sedentary people or hypertension patients, whoever sweats needs some salt as well, or they won’t retain the water they drink.

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