Wednesday, December 4, 2019

What is a scream? The acoustics of a primal human call

Getty Images

Screams are prompted by a variety of emotions — from joyful surprise to abject terror. No matter what sparks them, however, human screams share distinctive acoustic parameters that listeners are attuned to, suggests a new study published by the Journal of Nonverbal Behavior.

“Screams require a lot of vocal force and cause the vocal folds to vibrate in a chaotic, inconsistent way,” says senior author Harold Gouzoules, a professor of psychology at Emory University. “Despite the inherent variation in the way that screams are produced, our findings show that listeners can readily distinguish a scream from other human calls. And we are honing in on how they make that distinction.”

Jay Schwartz is first author of the paper and Jonathan Engleberg is a co-author. They are both Emory PhD candidates in Gouzoules’ Bioacoustics Lab. Gouzoules began researching monkey screams in 1980, before becoming one of the few scientists studying human screams about 10 years ago. He is interested in the origins of screams and the role they played in human development.

“Animal screams occur almost always in the context of a fight or in response to a predator,” Gouzoules says. “Human screams happen in a much broader array of contexts, which makes them much more interesting.”

Gouzoules' Bioacoustics Lab has amassed an impressive library of high-intensity, visceral sounds — from TV and movie performances to the screams of non-actors reacting to actual events posted to online sites such as YouTube.

For the current study, the researchers presented 182 participants with a range of human calls. Some of the calls were screams of aggression, exclamation, excitement, fear or pain. Others calls included cries, laughter and yells.

The participants showed strong agreement for what classified as a scream. An acoustical analysis for the calls the participants classified as screams, compared to those they did not, included a higher pitch and roughness, or harshness, to the sound; a wider variability in frequency; and a higher peak frequency.

The current paper is part of an extensive program of research into screams by Gouzoules. In another recently published article, his lab has found that listeners cannot distinguish acted screams from naturally occurring screams. Listeners can, however, correctly identify whether pairs of screams were produced by the same person or two different people.

Related:
Screams contain a calling card for vocalizer's identity

Thursday, October 24, 2019

The psychology of thrills and chills

Monsters do not thrill psychologist Ken Carter, shown at Netherworld in Stone Mountain. Photo by Kay Hinton.

Psychologist Kenneth Carter is not a fan of Halloween haunted houses. But he has written a book about people who thrive on activities like entering dark passageways, sensing that something unknown and terrifying awaits around the next corner.

“I don’t enjoy having things come out of nowhere,” says Carter, whose long-anticipated book “Buzz! Inside the Minds of Thrill-Seekers, Daredevils and Adrenaline Junkies” comes out October 31. “Buzz!” both educates and entertains with insights from real-life adventurers, such as a scaler of skyscrapers, known as “Spider Man,” who enjoys hanging from great heights suspended by only his fingers.

Cambridge University Press is publishing the book, the culmination of years of research into high sensation-seeking people by Carter, a professor at Oxford College of Emory University and a self-described low sensation-seeking personality type.

“I love Halloween because it brings both extremes together, there’s something for everyone,” Carter says. “For me, it’s candy corn. That’s my second favorite candy, after Smarties. I enjoy the sweet, silly side of Halloween — not the dark, scary side. I don’t want to get lost in a corn maze or watch ‘The Children of the Corn.’”

Read the full story here.

Monday, October 7, 2019

Navigating 'Neuralville': Virtual town helps map brain functions

While a PhD student at Emory, Andrew Persichetti developed experiments based on a virtual town he created, called "Neuralville," above, and a simple video game. "One of my favorite things about being a scientist is getting to design experiments," he says.

Psychologists at Emory University have found that the human brain uses three distinct systems to perceive our environment — one for recognizing a place, another for navigating through that place and a third for navigating from one place to another.

For a new paper, they designed experiments involving a simulated town and functional magnetic resonance imaging (fMRI) to gain new insights into such systems. Their results, published by the Proceedings of the National Academy of Sciences (PNAS), have implications ranging from more precise guidance for surgeons who operate on the brain to better computer vision systems for self-driving cars.

“We’re mapping the functions of the brain’s cortex with respect to our ability to recognize and get around our world,” says Daniel Dilks, Emory associate professor of psychology and senior author of the study. “The PNAS paper provides the last big piece in the puzzle.”

The experiments showed that the brain’s parahippocampal place area is involved in recognizing a particular kind of place in the virtual town, while the brain’s retrosplenial complex is involved in mentally mapping the locations of particular places in the town.

Read the full story here.

Tuesday, September 24, 2019

Study gets to root of rice's resilience to floods

"Our work is the most comprehensive look yet across species into what's really going on under the hood as plants respond to flooding," says Emory biologist Roger Deal. (Getty Images)

By Carol Clark

Climate change is increasing both the severity and frequency of extreme weather events, including floods. That’s a problem for many farmers, since rice is the only major food crop that’s resilient to flooding. A new study, published in Science, however, identified genetic clues to this resilience that may help scientists improve the prospects for other crops.

“Our work is the most comprehensive look yet across species into what’s really going on under the hood as plants respond to flooding,” says Roger Deal, associate professor of biology at Emory University and a lead author of the study. “Understanding the mechanism for flooding tolerance is the first step in understanding how you might increase it in plants that lack it.”

Rice was domesticated from wild species that grew in tropical regions, where it adapted to endure monsoons and waterlogging. The Science research looked at how other crops compare to rice when submerged in water. The plants included species with a range of flooding tolerance, from barrel clover (which is similar to alfalfa), to domesticated tomato plants, to a wild-growing tomato that is adapted for a desert environment.

The results showed that, although evolution separated the ancestors of rice and these other species as many as 180 million years ago, they all share at least 68 families of genes that are activated in response to flooding.

“That was surprising,” Deal says. “We thought we’d see different gene expression responses among these species related to their adaptation to wet or dry conditions. Instead, what was really different was that rice had far and away the most rapid and synchronous response. In comparison, the other plants’ responses were piecemeal and haphazard.”

The Deal lab experimented on barrel clover (Medicago truncatula) as part of the study. (Photo by Marko Bajic)

Deal’s research focuses on how plants build and adapt their bodies. By digging deep into the developmental biology and genetics of plant systems, he hopes to unearth secrets that could benefit both agriculture and human health.

Marko Bajic, an Emory graduate student in the Department of Biology and the Graduate Program in Genetics and Molecular Biology, is co-author of the Science paper.

The study was an international collaboration funded by the National Science Foundation’s Plant Genome Research Program. The authors include scientists from the University of California, Davis; the University of California, Riverside; Argentina’s National University of La Plata and the Netherland’s Ultrecht University.

UC Riverside researchers conducted flooding experiments and analysis of rice plant genomes, scientists at UC Davis did the same with the tomato species while the barrel clover work was done at Emory.

The results suggest that the timing and smoothness of the genetic response may account for the variations in the outcomes for the plants during the experiments.

The wild tomato species that grows in desert soil withered and died when flooded.

The team examined cells that reside at the tips of roots of plants, as roots are the first responders to a flood. Root tips and shoot buds are also where a plant’s prime growing potential resides. These regions contain cells with the ability to become other types of cells in the plant and serve as a repair system in plants and other living things.

Drilling down even further, the team looked at the genes in these root tip cells, to understand whether and how their genes were activated when covered with water and deprived of oxygen.

“We looked at the way that DNA instructs a cell to create particular stress responses in a level of unprecedented detail,” says Mauricio Reynoso, one of the lead authors from the University of California, Riverside.

The group is now planning additional studies to improve the survival rates of plants that currently die and rot from excess water.

This year is not the first in which excessive rains have kept farmers from being able to plant crops like corn, soybeans and alfalfa. Floods have also damaged the quality of the crops they were able to grow. This trend is expected to continue due to climate change.

“We as scientists have an urgency to help plants withstand floods, to ensure food security for the future,” says Julia Bailey-Serres, another lead author of the study and a professor of genetics at the University of California, Riverside.

Jules Bernstein, from the University of California, Riverside, contributed to this story. 

Related:
How zinnias shaped a budding biologist

Wednesday, September 18, 2019

DNA 'origami' takes flight in emerging field of nano machines

Making things out of DNA, nicknamed DNA origami after the traditional Japanese paper craft, is moving from a nanoscale novelty to a practical research tool. Emory chemists Khalid Salaita and Aaron Blanchard wrote about the emerging field of DNA mechanotechnology for the journal Science. (Getty Images)

By Carol Clark

Just as the steam engine set the stage for the Industrial Revolution, and micro transistors sparked the digital age, nanoscale devices made from DNA are opening up a new era in bio-medical research and materials science.

The journal Science describes the emerging uses of DNA mechanical devices in a “Perspective” article by Khalid Salaita, a professor of chemistry at Emory University, and Aaron Blanchard, a graduate student in the Wallace H. Coulter Department of Biomedical Engineering, a joint program of Georgia Institute of Technology and Emory.

The article heralds a new field, which Blanchard dubbed “DNA mechanotechnology,” to engineer DNA machines that generate, transmit and sense mechanical forces at the nanoscale.

“For a long time,” Salaita says, “scientists have been good at making micro devices, hundreds of times smaller than the width of a human hair. It’s been more challenging to make functional nano devices, thousands of times smaller than that. But using DNA as the component parts is making it possible to build extremely elaborate nano devices because the DNA parts self-assemble.”

Aaron Blanchard, left, an Emory graduate student of chemistry, and Khalid Salaita, professor of chemistry, are working at the forefront of DNA mechanotechnology.

DNA, or deoxyribonucleic acid, stores and transmits genetic information as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C) and thymine (T). The DNA bases have a natural affinity to pair up with each other — A with T and C with G. Synthetic strands of DNA can be combined with natural DNA strands from bacteriophages. By moving around the sequence of letters on the strands, researchers can get the DNA strands to bind together in ways that create different shapes. The stiffness of DNA strands can also easily be adjusted, so they remain straight as a piece of dry spaghetti or bend and coil like boiled spaghetti.

The idea of using DNA as a construction material goes back to the 1980s, when biochemist Nadrian Seeman pioneered DNA nanotechnology. This field uses strands of DNA to make functional devices at the nanoscale. The ability to make these precise, three-dimensional structures began as a novelty, nicknamed DNA origami, resulting in objects such as a microscopic map of the world and, more recently, the tiniest-ever game of tic-tac-toe, played on a DNA board.

Work on novelty objects continues to provide new insights into the mechanical properties of DNA. These insights are driving the ability to make DNA machines that generate, transmit and sense mechanical forces.

“If you put together these three main components of mechanical devices, you begin to get hammers and cogs and wheels and you can start building nano machines,” Salaita says. “DNA mechanotechnology expands the opportunities for research involving biomedicine and materials science. It’s like discovering a new continent and opening up fresh territory to explore.”

Watch a video about how DNA machines work


Potential uses for such devices include drug delivery devices in the form of nano capsules that open up when they reach a target site, nano computers and nano robots working on nanoscale assembly lines.

The use of DNA self-assembly by the genomics industry, for biomedical research and diagnostics, is further propelling DNA mechanotechnology, making DNA synthesis inexpensive and readily available. “Potentially anyone can dream up a nano-machine design and make it a reality,” Salaita says.

He gives the example of creating a pair of nano scissors. “You know that you need two rigid rods and that they need to be linked by a pivot mechanism,” he says. “By tinkering with some open-source software, you can create this design and then go onto a computer and place an order to custom synthesize your design. You’ll receive your order in a tube. You simply put the tube contents into a solution, let your device self-assemble, and then use a microscope to see if it works the way you thought that it would.”

The Salaita Lab is one of only about 100 around the world working at the forefront of DNA mechanotechnology. He and Blanchard developed the world’s strongest synthetic DNA-based motor, which was recently reported in Nano Letters.

A key focus of Salaita’s research is mapping and measuring how cells push and pull to learn more about the mechanical forces involved in the human immune system. Salaita developed the first DNA force gauges for cells, providing the first detailed view of the mechanical forces that one molecule applies to another molecule across the entire surface of a living cell. Mapping such forces may help to diagnose and treat diseases related to cellular mechanics. Cancer cells, for instance, move differently from normal cells, and it is unclear whether that difference is a cause or an effect of the disease.

Watch a video about the Salaita Lab's work with T cells


In 2016, Salaita used these DNA force gauges to provide the first direct evidence for the mechanical forces of T cells, the security guards of the immune system. His lab showed how T cells use a kind of mechanical “handshake” or tug to test whether a cell they encounter is a friend or foe. These mechanical tugs are central to a T cell’s decision for whether to mount an immune response.

“Your blood contains millions of different types of T cells, and each T cell is evolved to detect a certain pathogen or foreign agent,” Salaita explains. “T cells are constantly sampling cells throughout your body using these mechanical tugs. They bind and pull on proteins on a cell’s surface and, if the bond is strong, that’s a signal that the T cell has found a foreign agent.”

Salaita’s lab built on this discovery in a paper recently published in the Proceedings of the National Academy of Sciences (PNAS). Work led by Emory chemistry graduate student Rong Ma refined the sensitivity of the DNA force gauges. Not only can they detect these mechanical tugs at a force so slight that it is nearly one-billionth the weight of a paperclip, they can also capture evidence of tugs as brief as the blink of an eye.

The research provides an unprecedented look at the mechanical forces involved in the immune system. “We showed that, in addition to being evolved to detect certain foreign agents, T cells will also apply very brief mechanical tugs to foreign agents that are a near match,” Salaita says. “The frequency and duration of the tug depends on how closely the foreign agent is matched to the T cell receptor.”

The result provides a tool to predict how strong of an immune response a T cell will mount. “We hope this tool may eventually be used to fine tune immunotherapies for individual cancer patients,” Salaita says. “It could potentially help engineer T cells to go after particular cancer cells.”

Related:
Nano-walkers take speedy leap forward with first rolling DNA-based motor
T cells use 'handshakes' to sort friends from foes 
New methods reveal the mechanics of blood clotting 
Chemists reveal the force within you

Wednesday, September 11, 2019

Chameleons inspire 'smart skin' that changes color in the sun


A chameleon can alter the color of its skin so it either blends into the background to hide or stands out to defend its territory and attract a mate. The chameleon makes this trick look easy, using photonic crystals in its skin. Scientists, however, have struggled to make a photonic crystal “smart skin” that changes color in response to the environment, without also changing in size.

The journal ACS Nano published research led by chemists at Emory University that found a solution to the problem. They developed a flexible smart skin that reacts to heat and sunlight while maintaining a near constant volume.

“Watching a chameleon change colors gave me the idea for the breakthrough,” says first author Yixiao Dong, a PhD candidate in Emory’s Department of Chemistry. “We’ve developed a new concept for a color-changing smart skin, based on observations of how nature does it.”

Read the whole story and watch videos of the color-changing process here.

Getty Images

Tuesday, August 20, 2019

Skeletal shapes key to rapid recognition of objects

"You can think of it like a child's stick drawing of a person," says Emory psychologist Stella Lourenco, explaining the skeletal geometry that aids the vision system in object recognition. (Getty Images)

By Carol Clark

In the blink of an eye, the human visual system can process an object, determining whether it’s a cup or a sock within milliseconds, and with seemingly little effort. It’s well-established that an object’s shape is a critical visual cue to help the eyes and brain perform this trick. A new study, however, finds that while the outer shape of an object is important for rapid recognition, the object’s inner “skeleton” may play an even more important role.

Scientific Reports published the research by psychologists at Emory University, showing that a key visual tool for object recognition is the medial axis of an object, or its skeletal geometry.

“When we think of an object’s shape, we typically imagine the outer contours,” explains Vladislav Ayzenberg, first author of the paper and an Emory PhD candidate in psychology. “But there is also a deeper, more abstract property of shape that’s described by skeletal geometry. Our research suggests that this inner, invisible mechanism may be crucial to recognizing an object so quickly.”

“You can think of it like a child’s stick drawing of a person,” adds Stella Lourenco, senior author of the study and an associate professor of psychology at Emory. “Using a stick figure to represent a person gives you the basic visual information you need to immediately perceive the figure’s meaning.”

The Lourenco lab researches human visual perception, cognition and development. Visual perception of an object begins when light hits our eyes and the object is projected as a two-dimensional image onto the photoreceptor cells of the retina.

“A lot of internal machinery is whirring between the eyes and brain to facilitate perception and recognition within 70 milliseconds,” Ayzenberg says. “I’m fascinated by the neural computations that go into that process.”

Although most people take it for granted, object recognition is a remarkable feat. “You can teach a two-year-old what a dog is by pointing out a real dog or showing the child a picture in a book,” Lourenco says. “After seeing such examples a child can rapidly and with ease recognize other dogs as dogs, despite variations in their individual appearances.”



The human ability at object recognition is robust despite changes in a class of objects such as outer contours, sizes, textures and colors. For the current paper, the researchers developed a series of experiments to test the role of skeletal geometry in the process.

In one experiment, participants were presented with paired images of 150 abstract 3D objects on a computer. The objects had 30 different skeletal structures. Each object was rendered with five different surface forms, to change the visible shape of the object, without altering the underlying skeleton. The participants were asked to judge whether each pair of images showed the same or different objects. The results found that skeletal similarity was a significant predictor for a correct response.

A second experiment, based on adaptations of three of the objects, tested the effects of proportional changes to the shape skeleton. Participants were able to accurately predict object similarity at a rate significantly above chance at every level of skeletal change.

A third experiment tested whether an object’s skeleton was a better predictor of object similarity than its surface form. Participants successfully matched objects by their skeletal structure or surface forms when each cue was presented in isolation. They showed a preference, however, to match objects by their skeletons, as opposed to their surface forms, when these cues conflicted with one another.

The results suggest that the visual system is not only highly sensitive to the skeletal structure of objects, but that this sensitivity may play an even bigger role in shape perception than object contours.

“Skeletal geometry appears to be more important than previously realized, but it is certainly not the only tool used in object recognition,” Lourenco says. “It may be that the visual system starts with the skeletal structure, instead of the outline of an object, and then maps other properties, such as textures and colors, onto it.”

In addition to adding to fundamental knowledge of the human vision system, the study may give insights into improving capabilities for artificial intelligence (AI). Rapid and accurate object recognition, for example, is vital for AI systems on self-driving cars.

“The best model for a machine-learning system is likely a human-learning system,” Ayzenberg says. “The human vision system has solved the problem of object recognition through evolution and adapted quite well.”

Related:
Babies' spatial reasoning predicts later math skills
How babies use numbers, space and time 
How fear skews our spatial perception
Psychologists closing in on claustrophobia 

Thursday, August 1, 2019

Protection from mosquitoes key to avoid West Nile virus

"In Georgia, West Nile virus is primarily spread by the southern house mosquito Culex quinquefasciatus," says Gonzalo Vazquez-Prokopec, associate professor in Emory's Department of Environmental Sciences. (CDC/James Gathany)

August to September is the peak of the West Nile virus (WNV) season and Atlanta area health officials have reported finding mosquitoes testing positive for the pathogen, including from 11 locations across DeKalb County. No human cases, however, have been reported.

WNV is most commonly spread to people by the bite of an infected mosquito. Most people who become infected do not feel sick, but about one in five develop a fever and other symptoms. And about one out of 150 people infected develop a serious, sometimes fatal, illness, according to the CDC.

Gonzalo Vazquez-Prokopec, associate professor in Emory University's Department of Environmental Sciences, is an expert in mosquito-borne diseases. His lab has studied the urban ecology of metro Atlanta and the Culex mosquito — a vector for WNV and other human pathogens.

Vazquez-Prokopec is currently in the field in Brazil, but we caught up with him via email for a brief Q and A.

What should people know about the particular type of mosquito that spreads WNV?

In Georgia, West Nile virus is primarily spread by the southern house mosquito Culex quinquefasciatus. This light-brown colored species bites at dusk and dawn, and is found in high numbers in and around houses and in open areas, such as parks.

Is it normal to detect WNV in so many Atlanta-area mosquitoes this time of year? 

Yes, the infection rates in mosquitoes, gathered from different mosquito traps, are following trends that we’ve seen in previous years. What we do not see is human cases — so far this year none have been reported for Georgia.

Is Atlanta normally at higher or average risk for human cases of WNV? 

Human infection with WNV is low in Georgia compared to some states in the Northeast or Midwest. This is remarkably different from what we see in mosquitoes and birds which, in Atlanta, have equally high WNV levels compared to the Northeast and Midwest. What seems to be different is the rate of spillover of the virus, or transfer from the wildlife cycle to humans, which definitely appears to be suppressed in the Southeastern United States.

How can people best protect themselves? 

Reducing human exposure to Culex mosquitoes is key to maintaining the low rates of human infection. It’s best to follow the recommendations on the CDC web site to use insect repellent and wear long-sleeved shirts and long pants when outside to protect yourself from mosquito bites, and to remove any standing water around your home. Dekalb County has a great checklist on its web site to help locate potential mosquito breeding sites around your yard.

Related:
Cardinals may reduce West Nile virus spillover in Atlanta
Sewage raises West Nile virus risk

Wednesday, July 31, 2019

Chemists teach old drug new tricks to target deadly staph bacteria

Emory chemist Bill Wuest, far right, with some of his graduate students, from left: Erika Csatary, Madeleine Dekarske and Ingrid Wilt. Photo by Ann Watson.

"Saying superbugs, one antibiotic at a time,” is the motto of Bill Wuest’s chemistry lab at Emory University. Wuest (it rhymes with “beast”) leads a team of students fighting drug-resistant bacteria — some of the scariest, most dangerous bugs on the planet.

Most recently, they created new molecules for a study published in PNAS. Their work helped verify how bithionol — a drug used to treat parasitic infections — can weaken the cell membranes of “persister” cells of methicillin-resistant Staphylococcus aureus (MRSA), a deadly staph bacterium. They also synthesized new compounds, to learn more about how bithionol works and enhance its potential for clinical use.

“Just before I entered graduate school, my mother was diagnosed with a severe staph infection,” says Ingrid Wilt, a PhD candidate, explaining what drives her passion to tackle MRSA.

“She was in a hospital in the ICU for about two weeks,” Wilt adds. “Luckily, a last-resort antibiotic worked for her and she’s okay now.”

Click here to read the full story.

Related:
Chemistry students sing their studies, hoping for a good reaction
Brazilian peppertree packs power to knock out antibiotic-resistant bacteria

Monday, July 22, 2019

Cheerleader study highlights need for real-time energy balance

"It's not just how much you eat and what you eat but when you eat it that matters," says Dan Benardot, senior author of the study and a professor of practice at Emory's Center for the Study of Human Health.

It’s well-known that many athletes, especially women athletes and those participating in sports with an aesthetic component, can be chronically energy deficient. A new study suggests that professional cheerleaders also struggle to maintain an optimal balance between energy consumed and energy burned during exercise.

The Journal of Science in Sport and Exercise published the finding, led by researchers at Emory University’s Center for the Study of Human Health and Rollins School of Public Health. The results showed that some study participants had hourly energy balance deficits that were significantly below their estimated energy needs during a typical training day.

“An offensive lineman doesn’t have to worry about what he looks like but appearance matters for professional cheerleaders, and that may affect their food choices,” says Moriah Bellissimo, first author of the study and a graduate student at Rollins. “Some of our study participants reported really low caloric intakes for the amount of physical training they do. Those with the lowest caloric intakes were not eating enough to maintain an optimal body composition of lean mass compared to fat for high-performance athletics.”

“It is not just how much you eat and what you eat but when you eat it that matters,” adds senior author Dan Benardot, professor of practice at Emory’s Center for the Study of Human Health.

Benardot, who is also an emeritus professor of nutrition at Georgia State University, is an expert in the interrelationship between energy intake, body composition and within-day energy balance, and has worked as a team nutritionist for Olympians and professional athletes.

“The body works in real time,” Benardot says. “If you’re not eating enough and not often enough to avoid low blood sugar and high cortisol, your body adapts to this negative energy balance. Your brain will direct the body to find more energy by breaking down muscle mass to satisfy the need for energy. It sets you up for a downward spiral where you continually have to eat less and less to keep from gaining weight.”

The problem is particularly acute for athletes, especially female athletes and those in aesthetic sports, who deplete lean muscle mass at a faster rate than less active people because of the exercise-associated severe energy balance deficit they achieve. The researchers wanted to investigate whether professional cheerleaders, who may train four hours a day practicing dance routines, faced a similar challenge for real-time energy balance as some other female athletes in aesthetic sports.

“I have a vested interest in human performance and nutrition from a personal standpoint,” says Bellissimo, who was a collegiate athlete for five years before entering the Rollins PhD program for Nutrition and Health Science. “I know that how you are eating makes a difference in how you perform.”

Bellissimo says it was challenging to maintain a proper nutritional balance when she was an undergraduate and master’s student, while also competing in Division I volleyball tournaments. She notes that professional cheerleaders often work full-time jobs on top of training and performing and may find it especially challenging to carefully strategize all of their nutritional needs.

For the current study, the researchers conducted 24-hour dietary and activity surveys with professional cheerleaders during an active training period — including an hour-by-hour assessment of what and how much they ate, and hourly energy expenditures throughout the day. They inputted the data into a software tool called NutriTiming®, developed by Benardot, to calculate each participants’ hourly energy balance — and whether they were exercising at a calorie surplus or deficit.

For female athletes, previous research has shown that sustaining an energy balance of plus or minus 300 calories throughout the day is beneficial to avoid the lean tissue breakdown associated with larger energy deficits.

The body mass and body composition of the study participants was also measured, using a bioelectrical impedance analyzer — which painlessly assesses the density of biological tissue.

The results showed that those participants who spent fewer hours in a negative energy balance had a lower, more optimal, percentage of body fat and those who spent more time within the plus-or-minus zone of 300 calories also had a lower percentage of body fat.

The cheerleader study was small and of short duration, but the finding is consistent with other research on female athletes and other populations, Benardot says.

“Athletes expend energy rapidly,” he adds. “They need to eat frequently, just not too much at a time, so their bodies have enough fuel to burn as they need it.”

It is important to study the nutritional needs of people involved in competitive sports and other intensive exercise, both to help them perform at their maximum level and to maintain their health, Bellissimo says. “Research has shown that chronic energy balance deficits in athletes can lead to hormonal imbalances, and that can have long-term health implications,” she says.

Additional authors of the study include Ashley Licata, from the University of Alabama at Birmingham, and Anita Nucci and Walt Thompson, from Georgia State University.

Related:
'Nutrition for the Performing Arts' course focuses on science behind peak performance

Friday, July 5, 2019

Emory mathematician to present a proof of the Sensitivity Conjecture

Emory mathematician Hao Huang says that the algebraic tool that he developed to tackle the problem "might also have some potential to be applied to other combinatorial and complexity problems important to computer science.”

The Sensitivity Conjecture has stood as one of the most important, and baffling, open problems in theoretical computer science for nearly three decades. It appears to have finally met its match through work by Hao Huang, an assistant professor of mathematics at Emory University.

Huang will present a proof of the Sensitivity Conjecture during the International Conference on Random Structures and Algorithms, set for Zurich, Switzerland, July 15 to 19.

“I’ve been attacking this problem off and on since 2012,” Huang says, “but the key idea emerged for me just about a week ago. I finally identified the right tool to solve it.”

Huang posted the proof on his home page and it soon generated buzz among mathematicians and computer scientists on social media, who have praised its remarkable conciseness and simplicity.

The Sensitivity Conjecture relates to boolean data, which maps information into a true-false, or 1-0 binary. Boolean functions play an important role in complexity theory, as well in the design of circuits and chips for digital computers.

“In mathematics, a boolean function is one of the most basic discrete subjects — just like numbers, graphs or geometric shapes,” Huang explains.

There are many complexity measures of a boolean function, and almost all of them — including the decision-tree complexity, the certificate complexity, the randomized query complexity and many others — are known to be polynomially related. However, there is one unknown case, the so-called sensitivity of a boolean function, which measures how sensitive the function is when changing one input at a time.

In 1994, mathematicians Noam Nisan and Mario Szegedy proposed the Sensitivity Conjecture concerning this unknown case.

“Their conjecture says the sensitivity of a boolean function is also polynomially related to the other measures,” Huang says. “If true, then it would cease to be an outlier and it would join the rest of them.”

Huang developed an algebraic method for proving the conjecture. “I hope this method might also have some potential to be applied to other combinatorial and complexity problems important to computer science,” he says.

The research was supported in part by the Simons Foundation.

Monday, June 24, 2019

Screams contain a 'calling card' for the vocalizer's identity

"Our findings add to our understanding of how screams are evolutionarily important," says Emory psychologist Harold Gouzoules, senior author of the paper.

By Carol Clark

Human screams convey a level of individual identity that may help explain their evolutionary origins, finds a study by scientists at Emory University.

PeerJ published the research, showing that listeners can correctly identify whether pairs of screams were produced by the same person or two different people — a critical prerequisite to individual recognition.

“Our findings add to our understanding of how screams are evolutionarily important,” says Harold Gouzoules, senior author of the paper and an Emory professor of psychology. “The ability to identify who is screaming is likely an adaptive mechanism. The idea is that you wouldn’t respond equally to just anyone’s scream. You would likely respond more urgently to a scream from your child, or from someone else important to you.”

Jonathan Engelberg is first author of the paper and Jay Schwartz is a co-author. They are both Emory PhD candidates in Gouzoules’ Bioacoustics Lab.

The ability to recognize individuals by distinctive cues or signals is essential to the organization of social behavior, the authors note, and humans are adept at making identity-related judgements based on speech — even when the speech is heavily altered. Less is known, however, about identity cues in nonlinguistic vocalizations, such as screams.

Gouzoules first began researching monkey screams in 1980, before becoming one of the few scientists studying human screams about 10 years ago.

“The origin of screams was likely to startle a predator and make it jump, perhaps allowing the prey a small chance to escape,” Gouzoules says. “That’s very different from calling out for help.”

He theorizes that as some species became more social, including monkeys and other primates, screams became a way to recruit help from relatives and friends when someone got into trouble.

Previous research by Gouzoules and others suggests that non-human primates are able to identify whether a scream is coming from an individual that is important to them. Some researchers, however, have disputed the evidence, arguing that the chaotic and inconsistent nature of screams does not make them likely conduits for individual recognition.

Gouzoules wanted to test whether humans could determine if two fairly similar screams were made by the same person or a different person. His Bioacoustics Lab has amassed an impressive library of high-intensity, visceral sounds — from TV and movie performances to the screams of non-actors reacting to actual events on YouTube videos.

For the PeerJ paper, the lab ran experiments that included 104 participants. The participants listened to audio files of pairs of screams on a computer, without any visual cues for context. Each pair was presented two seconds apart and participants were asked to determine if the screams came from the same person or a different person.

In some trials, the two screams came from two different callers, but were matched by age, gender and the context of the scream. In other trials, the screams came from the same caller but were two different screams matched for context. And in a third trial, the stimulus pairs consisted of a scream and a slightly modified version of itself, to make it longer or shorter than the original.

For all three of the experiments, most of the participants were able to correctly judge most of the time whether the screams were from the same person or not.

“Our results provide empirical evidence that screams carry enough information for listeners to discriminate between different callers,” Gouzoules says. “Although screams may not be acoustically ideal for signaling a caller’s identity, natural selection appears to have adequately shaped them so they are good enough to do the job.”

The PeerJ paper is part of an extensive program of research into screams by Gouzoules. In previous work, his lab has found that listeners cannot distinguish acted screams from naturally occurring screams.

In upcoming papers, he is zeroing in on how people determine whether they are hearing a scream or some other vocalization and how they perceive the emotional context of a scream — judging whether it’s due to happiness, anger, fear or pain.

Photo: Getty Images

Related:
The psychology of screams

Thursday, June 13, 2019

The whisper of schizophrenia: Machine learning finds 'sound' words predict psychosis

"Machine learning technology is advancing so rapidly that it's giving us tools to data mine the human mind," says Emory psychologist Phillip Wolff, senior author of the study.

By Carol Clark

A machine-learning method discovered a hidden clue in people’s language predictive of the later emergence of psychosis — the frequent use of words associated with sound. The journal npj Schizophrenia published the findings by scientists at Emory University and Harvard University.

The researchers also developed a new machine-learning method to more precisely quantify the semantic richness of people’s conversational language, a known indicator for psychosis.

Their results show that automated analysis of the two language variables — more frequent use of words associated with sound and speaking with low semantic density, or vagueness — can predict whether an at-risk person will later develop psychosis with 93 percent accuracy.

Even trained clinicians had not noticed how people at risk for psychosis use more words associated with sound than the average, although abnormal auditory perception is a pre-clinical symptom.

“Trying to hear these subtleties in conversations with people is like trying to see microscopic germs with your eyes,” says Neguine Rezaii, first author of the paper. “The automated technique we’ve developed is a really sensitive tool to detect these hidden patterns. It’s like a microscope for warning signs of psychosis.”

Rezaii began work on the paper while she was a resident at Emory School of Medicine’s Department of Psychiatry and Behavioral Sciences. She is now a fellow in Harvard Medical School’s Department of Neurology.

“It was previously known that subtle features of future psychosis are present in people’s language, but we’ve used machine learning to actually uncover hidden details about those features,” says senior author Phillip Wolff, a professor of psychology at Emory. Wolff’s lab focuses on language semantics and machine learning to predict decision-making and mental health.

“Our finding is novel and adds to the evidence showing the potential for using machine learning to identify linguistic abnormalities associated with mental illness,” says co-author Elaine Walker, an Emory professor of psychology and neuroscience who researches how schizophrenia and other psychotic disorders develop.

The onset of schizophrenia and other psychotic disorders typically occurs in the early 20s, with warning signs — known as prodromal syndrome — beginning around age 17. About 25 to 30 percent of youth who meet criteria for a prodromal syndrome will develop schizophrenia or another psychotic disorder.

Using structured interviews and cognitive tests, trained clinicians can predict psychosis with about 80 percent accuracy in those with a prodromal syndrome. Machine-learning research is among the many ongoing efforts to streamline diagnostic methods, identify new variables, and improve the accuracy of predictions.

Currently, there is no cure for psychosis.

“If we can identify individuals who are at risk earlier and use preventive interventions, we might be able to reverse the deficits,” Walker says. “There are good data showing that treatments like cognitive-behavioral therapy can delay onset, and perhaps even reduce the occurrence of psychosis.”

For the current paper, the researchers first used machine learning to establish “norms” for conversational language. They fed a computer software program the online conversations of 30,000 users of Reddit, a social media platform where people have informal discussions about a range of topics. The software program, known as Word2Vec, uses an algorithm to change individual words to vectors, assigning each one a location in a semantic space based on its meaning. Those with similar meanings are positioned closer together than those with far different meanings.

The Wolff lab also developed a computer program to perform what the researchers dubbed “vector unpacking,” or analysis of the semantic density of word usage. Previous work has measured semantic coherence between sentences. Vector unpacking allowed the researchers to quantify how much information was packed into each sentence.

After generating a baseline of “normal” data, the researchers applied the same techniques to diagnostic interviews of 40 participants that had been conducted by trained clinicians, as part of the multi-site North American Prodrome Longitudinal Study (NAPLS), funded by the National Institutes of Health. NAPLS is focused on young people at clinical high risk for psychosis. Walker is the principal investigator for NAPLS at Emory, one of nine universities involved in the 14-year project.

The automated analyses of the participant samples were then compared to the normal baseline sample and the longitudinal data on whether the participants converted to psychosis.

The results showed that higher than normal usage of words related to sound, combined with a higher rate of using words with similar meaning, meant that psychosis was likely on the horizon.

Strengths of the study include the simplicity of using just two variables — both of which have a strong theoretical foundation — the replication of the results in a holdout dataset, and the high accuracy of its predictions, at above 90 percent.

“In the clinical realm, we often lack precision,” Rezaii says. “We need more quantified, objective ways to measure subtle variables, such as those hidden within language usage.”

Rezaii and Wolff are now gathering larger data sets and testing the application of their methods on a variety of neuropsychiatric diseases, including dementia.

“This research is interesting not just for its potential to reveal more about mental illness, but for understanding how the mind works — how it puts ideas together,” Wolff says. “Machine learning technology is advancing so rapidly that it’s giving us tools to data mine the human mind.”

The work was supported by grants from the National Institutes of Health and a Google Research Award.

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Wednesday, June 12, 2019

A focus on fathers: The science of dads

Anthropologist James Rilling with his son Toby, 8, and daughter Mia, 2. (Photo by Becky Stein)

Want to do something special for a father on June 16? Try asking him what he finds most rewarding — and most challenging — about being a dad.

James Rilling, an anthropologist at Emory University, recently completed in-depth interviews on that topic with 120 new fathers. Rilling and his colleague Craig Hadley, also an anthropologist at Emory, are still analyzing data from the interviews for a comprehensive study.

One result, however, is already clear. A positive-and-negative-affect scale administered to the subjects before and after the interviews shows how talking about fatherhood influenced their moods. “Most of them experienced an increase in how enthusiastic, proud and inspired they felt after talking about their experience as a father,” Rilling says. “They seemed to find it therapeutic to talk about their feelings surrounding being a father, particularly if they were struggling with some things. The challenges of being a mother are often much greater. So fathers may think that nobody really wants to hear about the things they are dealing with as a new parent.”

Read more about Rilling's work here, and learn five surprising facts about fathers.

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Tuesday, June 4, 2019

How chronic inflammation may drive down dopamine and motivation

“If our theory is correct, then it could have a tremendous impact on treating cases of depression and other behavioral disorders that may be driven by inflammation,” says co-author Andrew Miller, an Emory professor of psychiatry. (Getty Images)

By Carol Clark

Growing evidence shows that the brain’s dopamine system, which drives motivation, is directly affected by chronic, low-grade inflammation. A new paper proposes that this connection between dopamine, effort and the inflammatory response is an adaptive mechanism to help the body conserve energy.

Trends in Cognitive Sciences published the theoretical framework developed by scientists at Emory University. The authors also provided a computational method to experimentally test their theory.

“When your body is fighting an infection or healing a wound, your brain needs a mechanism to recalibrate your motivation to do other things so you don’t use up too much of your energy,” says corresponding author Michael Treadway, an associate professor in Emory’s Department of Psychology, who studies the relationship between motivation and mental illness. “We now have strong evidence suggesting that the immune system disrupts the dopamine system to help the brain perform this recalibration.”

The computational method will allow scientists to measure the effects of chronic inflammation on energy availability and effort-based decision-making. The method may yield insights into how chronic, low-grade inflammation contributes to motivational impairments in some cases of depression, schizophrenia and other medical disorders.

Co-author Andrew Miller, William P. Timmie Professor of Psychiatry and Behavioral Sciences in Emory’s School of Medicine and the Winship Cancer Institute, is a leader in this field and is pioneering the development of immunotherapeutic strategies for the treatment of psychiatric disorders.

“If our theory is correct, then it could have a tremendous impact on treating cases of depression and other behavioral disorders that may be driven by inflammation,” Miller says. “It would open up opportunities for the development of therapies that target energy utilization by immune cells, which would be something completely new in our field.”

Co-author Jessica Cooper, a post-doctoral fellow in Treadway’s lab, led the development of the computational model.

It has previously been shown that inflammatory cytokines — signaling molecules used by the immune system — impact the mesolimbic dopamine system. And recent research has revealed more insights into how immune cells can shift their metabolic states differently from most other cells.

The researchers built on these findings to develop their theoretical framework.

An immune-system mechanism to help regulate the use of energy resources during times of acute stress was likely adaptive in our ancestral environments, rife with pathogens and predators. In modern environments, however, many people are less physically active and may have low-grade inflammation due to factors such as chronic stress, obesity, metabolic syndrome, aging and other factors. Under these conditions, the same mechanism to conserve energy for the immune system could become maladaptive, the authors theorize.

Studies by Miller and others have provided evidence of an association between an elevated immune system, reduced levels of dopamine and motivation, and some diagnoses of depression, schizophrenia and other mental disorders.

“We’re not proposing that inflammation causes these disorders,” Treadway says. “The idea is that a subset of people with these disorders may have a particular sensitivity to the effects of the immune system and this sensitivity could contribute to the motivational impairments they are experiencing.”

The researchers are now using their computational method to test their theory in a clinical trial on depression.

The work for the current paper was supported by the National Institute of Mental Health.

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Thursday, May 23, 2019

Civil War plant medicines blast drug-resistant bacteria

Micah Dettweiler gathered samples for the study from Lullwater Forest on the Emory campus. He began the project for his honors thesis as an Emory undergraduate majoring in biology.

During the height of the Civil War, the Confederate Surgeon General commissioned a guide to traditional plant remedies of the South, as battlefield physicians faced high rates of infections among the wounded and shortages of conventional medicines.

A new study of three of the plants from this guide — the white oak, the tulip poplar and the devil’s walking stick — finds that they have antiseptic properties. Scientific Reports published the results of the study led by scientists at Emory University. The results show that extracts from the plants have antimicrobial activity against one or more of a trio of dangerous species of multi-drug-resistant bacteria associated with wound infections: Acinetobacter baumannii, Staphylococcus aureus and Klebsiella pneumoniae.

Read more about the study here.

Tuesday, May 21, 2019

Mathematicians revive abandoned approach to the Riemann Hypothesis

The idea for the paper was sparked by a "toy problem" that Emory mathematician Ken Ono (left) presented as a "gift" to entertain Don Zagier (right), of the Max Planck Institute of Mathematics, to celebrate Zagier's 65th birthday. The toy problem is seen on the whiteboard behind them.

By Carol Clark

Many ways to approach the Riemann Hypothesis have been proposed during the past 150 years, but none of them have led to conquering the most famous open problem in mathematics. A new paper in the Proceedings of the National Academy of Sciences (PNAS) suggests that one of these old approaches is more practical than previously realized.

“In a surprisingly short proof, we’ve shown that an old, abandoned approach to the Riemann Hypothesis should not have been forgotten,” says Ken Ono, a number theorist at Emory University and co-author of the paper. “By simply formulating a proper framework for an old approach we’ve proven some new theorems, including a large chunk of a criterion which implies the Riemann Hypothesis. And our general framework also opens approaches to other basic unanswered questions.”

The paper builds on the work of Johan Jensen and George Pólya, two of the most important mathematicians of the 20th century. It reveals a method to calculate the Jensen-Pólya polynomials — a formulation of the Riemann Hypothesis — not one at a time, but all at once.

“The beauty of our proof is its simplicity,” Ono says. “We don’t invent any new techniques or use any new objects in math, but we provide a new view of the Riemann Hypothesis. Any reasonably advanced mathematician can check our proof. It doesn’t take an expert in number theory.”

Read a commentary on the paper by Fields Medalist Enrico Bombieri.

Although the paper falls short of proving the Riemann Hypothesis, its consequences include previously open assertions which are known to follow from the Riemann Hypothesis, as well as some proofs of conjectures in other fields.

Co-authors of the paper are Michael Griffin and Larry Rolen — two of Ono’s former Emory graduate students who are now on the faculty at Brigham Young University and Vanderbilt University, respectively — and Don Zagier of the Max Planck Institute of Mathematics.

“The result established here may be viewed as offering further evidence toward the Riemann Hypothesis, and in any case, it is a beautiful stand-alone theorem,” says Kannan Soundararajan, a mathematician at Stanford University and an expert on the Riemann Hypothesis.

"Math at a research level is often more art than calculation and that was certainly the case here," says co-author Michael Griffin, an Emory grad who is now on the faculty at Brigham Young University.

The idea for the paper was sparked two years ago by a “toy problem” that Ono presented as a “gift” to entertain Zagier during the lead-up to a math conference celebrating his 65th birthday. A toy problem is a scaled-down version of a bigger, more complicated problem that mathematicians are trying to solve. Zagier described the one that Ono gave him as “a cute problem about the asymptotic behavior of certain polynomials involving Euler’s partition function, which is an old love of mine and of Ken’s — and of about pretty much any classical number theorist.”

“I found the problem intractable and I didn’t really expect Don to get anywhere with it,” Ono recalls. “But he thought the challenge was super fun and soon he had crafted a solution.”

Ono’s hunch was that such a solution could be crafted into a more general theory. That’s what the mathematicians ultimately achieved.

“It’s been a fun project to work on, a really creative process,” Griffin says. “Math at a research level is often more art than calculation and that was certainly the case here. It required us to look at an almost 100-year-old idea of Jensen and Pólya in a new way.”

The Riemann Hypothesis is one of seven Millennium Prize Problems, identified by the Clay Mathematics Institute as the most important open problems in mathematics. Each problem carries a $1 million bounty for its solvers.

The method outlined in the PNAS paper "has a shocking sense of being universal, in that it applies to problems that are seemingly unrelated," says co-author Larry Rolen, an Emory grad now on the faculty at Vanderbilt University.

The hypothesis debuted in an 1859 paper by German mathematician Bernhard Riemann. He noticed that the distribution of prime numbers is closely related to the zeros of an analytical function, which came to be called the Riemann zeta function. In mathematical terms, the Riemann Hypothesis is the assertion that all of the nontrivial zeros of the Zeta function have real part ½.

“His hypothesis is a mouthful, but Riemann’s motivation was simple,” Ono says. “He wanted to count prime numbers.”

Bernhard Riemann
The hypothesis is a vehicle to understand one of the greatest mysteries in number theory — the pattern underlying prime numbers. Although prime numbers are simple objects defined in elementary math (any number greater than 1 with no positive divisors other than 1 and itself) their distribution remains hidden.

The first prime number, 2, is the only even one. The next prime number is 3, but primes do not follow a pattern of every third number. The next is 5, then 7, then 11. As you keep counting upwards, prime numbers rapidly become less frequent.

“It’s well known that there are infinitely many prime numbers, but they become rare, even by the time you get to the 100s,” Ono explains. “In fact, out of the first 100,000 numbers, only 9,592 are prime numbers, or roughly 9.5 percent. And they rapidly become rarer from there. The probability of picking a number at random and having it be prime is zero. It almost never happens.”

In 1927, Jensen and Pólya formulated a criterion for confirming the Riemann Hypothesis, as a step toward unleashing its potential to elucidate the primes and other mathematical mysteries. The problem with the criterion — establishing the hyperbolicity of the Jensen-Pólya polynomials — is that it is infinite. During the past 90 years, only a handful of the polynomials in the sequence have been verified, causing mathematicians to abandon this approach as too slow and unwieldy.

For the PNAS paper, the authors devised a conceptual framework that combines the polynomials by degrees. This method enabled them to confirm the criterion for each degree 100 percent of the time, eclipsing the handful of cases that were previously known.

“The method has a shocking sense of being universal, in that it applies to problems that are seemingly unrelated,” Rolen says. “And at the same time, its proofs are easy to follow and understand. Some of the most beautiful insights in math are ones that took a long time to realize, but once you see them, they appear simple and clear.”

Despite their work, the results don’t rule out the possibility that the Riemann Hypothesis is false and the authors believe that a complete proof of the famous conjecture is still far off.

The work was supported by grants from the National Science Foundation and the Asa Griggs Candler Fund.

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Monday, May 13, 2019

Artificial intelligence and 'deep ethics'

In the sci-fi film “2001: A Space Odyssey,” astronauts go into a soundproof pod to discuss their concerns about some of the decisions made by the supercomputer Hal (seen through the window) without realizing that Hal knows how to lip read.

Advances in neurotechnology, genetics and artificial intelligence are not only going to change society as a whole, they are actually going to challenge what it means to be human and change our ethics, argues Paul Root Wolpe, director of the Emory Center for Ethics, in a recent TEDx Atlanta talk.

He uses self-driving cars as just one example.

“These vehicles are going to be going down the road and in a crisis they’re going to have to make decisions about what to do,” Wolpe says. “Do I crash into the wall and endanger my passengers or do I turn left and hit those pedestrians? For the first time we’re going to have to create ethical algorithms. That is, we’re going to have to teach a vehicle to make ethical decisions. For the first time, machines will be making ethical decisions that will have a profound impact on human beings.” 

Watch Wolpe’s talk in the video below to learn what he means by the term “deep ethics,” and how artificial intelligence may someday help us navigate through the ethical complexities raised by technology itself.



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Thursday, April 18, 2019

Ginkgo seed extracts show antibacterial activity on skin pathogens

The fan-shaped leaves of a ginkgo tree on the Emory campus, just off the Quad on the west end of Carlos Hall. The tree led a student to an ancient Chinese text and a laboratory discovery. (Photo by Ann Watson)

Extracts from the seeds of the Ginkgo biloba tree show antibacterial activity on pathogens that can cause skin infections such as acne, psoriasis, dermatitis and eczema, a study at Emory University finds. Frontiers in Microbiology is publishing the results of laboratory experiments showing that the extracts inhibit the growth of Cutibacterium acnes, Staphylococcus aureus and Streptococcus pyogenes.

A nearly 200-year-old copy of a 16th-century text on traditional Chinese medicine, the Ben Cao Gang Mu, guided the researchers in their experiments. “It was like blowing the dust off knowledge from the past and rediscovering something that had been there all along,” says Xinyi (Xena) Huang, co-first author of the paper.

Huang, a native of China, began the project for her senior thesis as a biology major at Emory. She has since graduated from Emory and is now a student at the University of Maryland School of Pharmacy.

“To the best of our knowledge, this is the first study to demonstrate the antibacterial activity of ginkgo seeds on skin pathogens,” says Cassandra Quave, senior author of the paper and assistant professor at Emory’s Center for the Study of Human Health and the School of Medicine’s Department of Dermatology. “This paper is just one more example of how much we still have to learn about the pharmacological potential of the complex chemistry of plants.”

Quave is an ethnobotanist, studying how indigenous people use plants in their healing practices, to uncover promising candidates for new drugs. Read more about the discovery.

Click here to read more about the discovery.

Thursday, April 11, 2019

When do children alter behavior to please others?


“I have spent the past four years at Emory University investigating how an infant, who has no problem walking around the grocery store in her onesie, develops into an adult that fears public speaking for fear of being negatively judged,” says Sara Botto in her newly released TEDxAtlanta talk.

Botto is a doctoral candidate in the Cognition and Development program of Emory’s Department of Psychology. Together with Emory psychologist Philippe Rochat, she designed experiments to investigate when in development we become sensitive to others’ evaluations — a big part of being human.

Watch the TEDxAtlanta video below to see young children reacting to the opinions of others during the experiments, which take the form of a game called “The Robot Task.”

Botto’s research showed that, even before they can form a simple sentence, children are sensitive to the evaluations of others, and alter their behavior accordingly.

“Whether we’re aware of it or not, we’re constantly communicating values to others,” Botto says. “We’re communicating a value when we mostly compliment girls for their pretty hair or their pretty dress but boys for their intelligence. Or when we choose to offer candy as opposed to nutritious food as a reward for good behavior.”

Visit Botto’s web site, AdultingWithKids.com, to learn more about credible, science-based child development research.




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Gender gap in spatial reasoning starts in elementary school, meta-analysis finds

"We're interested in the origins of gender differences in spatial skills because of their potential role in the gender gap we see in math and science fields," says Jillian Lauer, who is set to graduate from Emory in May with a PhD in psychology. (Getty Images)

By Carol Clark

It is well-established that, on average, men outperform women on a spatial reasoning task known as mental rotation — imagining multi-dimensional objects from different points of view. Men are not, however, born with this advantage, suggests a major meta-analysis by psychologists at Emory University. Instead, males gain a slight advantage in mental-rotation performance during the first years of formal schooling, and this advantage slowly grows with age, tripling in size by the end of adolescence.

The Psychological Bulletin, a journal of the American Psychological Association, is publishing the findings.

“Some researchers have argued that there is an intrinsic gender difference in spatial reasoning — that boys are naturally better at it than girls,” says lead author Jillian Lauer, who is set to graduate from Emory in May with a PhD in psychology. “While our results don’t exclude any possibility that biological influences contribute to the gender gap, they suggest that other factors may be more important in driving the gender difference in spatial skills during childhood.”

Co-authors of the paper include Stella Lourenco, associate professor of psychology at Emory, whose lab specializes in the development of spatial and numerical cognition. Co-author Eukyung Yhang worked on the paper as an Emory undergraduate, funded by the university’s Institute for Quantitative Theory and Methods. Yhang graduated in 2018 and is now at Yale University School of Medicine.

The meta-analysis included 128 studies of gender differences in spatial reasoning, combining statistics on more than 30,000 children and adolescents aged three to 18 years. The authors found no gender difference in mental-rotation skills among preschoolers, but a small male advantage emerged in children between the ages of six and eight.

While differences in verbal and mathematical abilities between men and women tend to be small or non-existent, twice as many men as women are top performers in mental rotation, making it one of the largest gender differences in cognition.

Mental rotation is considered one of the hallmarks of spatial reasoning. “If you’re packing your suitcase and trying to figure out how each item can fit within that space, or you’re building furniture based on a diagram, you’re likely engaged in mental rotation, imagining how different objects can rotate to fit together,” Lauer explains.

It takes most of childhood and adolescence for the gender gap in spatial skills to reach the size of the difference seen in adulthood.

Prior research has also shown that superior spatial skills predict success in male-dominated science, technology engineering and math (STEM) fields, and that the gender difference in spatial reasoning may contribute to the gender disparity in these STEM fields.

“We’re interested in the origins of gender differences in spatial skills because of their potential role in the gender gap we see in math and science fields,” Lauer says. “By determining when the gender difference can first be detected in childhood and how it changes with age, we may be able to develop ways to make educational systems more equitable.”

It takes most of childhood and adolescence for the gender gap in spatial skills to reach the size of the difference seen in adulthood, Lauer says. She adds that the meta-analysis did not address causes for why the gender gap for mental rotation emerges and grows.

Lauer notes that previous research has shown that parents use more spatial language when they talk to preschool sons than daughters. Studies have also found that girls report more anxiety about having to perform spatial tasks than do boys by first grade, and that children are aware of gender stereotypes about spatial intelligence during elementary school.

“Now that we’ve characterized how gender differences in spatial reasoning skills develop in children over time we can start to hone in on the reasons for those differences,” Lauer says.

Meanwhile, she adds, parents may want to be aware to encourage both their daughters and sons to play with blocks and other construction items that might help in the development of spatial reasoning skills, since evidence shows that these skills can be improved with training.

“Giving both girls and boys more opportunities to develop their spatial skills is something that parents and educators have the power to do,” Lauer says.

Lauer has accepted a post-doctoral fellowship position at New York University. Her PhD advisor is Patricia Bauer, a professor of psychology at Emory focused on cognition and child development.

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Wednesday, March 27, 2019

Machine learning used to understand and predict dynamics of worm behavior

The roundworm C. elegans is a well-established laboratory model system. While the worm is a fairly simple living system, it is complicated enough to serve as "a kind of sandbox" for testing out methods of automated inference, says Emory biophysicist Ilya Nemenman. (Getty Images)

By Carol Clark

Biophysicists have used an automated method to model a living system — the dynamics of a worm perceiving and escaping pain. The Proceedings of the National Academy of Sciences (PNAS) published the results, which worked with data from experiments on the C. elegans roundworm.

“Our method is one of the first to use machine-learning tools on experimental data to derive simple, interpretable equations of motion for a living system,” says Ilya Nemenman, senior author of the paper and a professor of physics and biology at Emory University. “We now have proof of principle that it can be done. The next step is to see if we can apply our method to a more complicated system.”

The model makes accurate predictions about the dynamics of the worm behavior, and these predictions are biologically interpretable and have been experimentally verified.

Collaborators on the paper include first author Bryan Daniels, a theorist from Arizona State University, and co-author William Ryu, an experimentalist from the University of Toronto.

The researchers used an algorithm, developed in 2015 by Daniels and Nemenman, that teaches a computer how to efficiently search for the laws that underlie natural dynamical systems, including complex biological ones. They dubbed the algorithm “Sir Isaac,” after one of the most famous scientists of all time — Sir Isaac Newton. Their long-term goal is to develop the algorithm into a “robot scientist,” to automate and speed up the scientific method of forming quantitative hypotheses, then testing them by looking at data and experiments.

While Newton’s Three Laws of Motion can be used to predict dynamics for mechanical systems, the biophysicists want to develop similar predictive dynamical approaches that can be applied to living systems.

For the PNAS paper, they focused on the decision-making involved when C. elegans responds to a sensory stimulus. The data on C. elegans had been previously gathered by the Ryu lab, which develops methods to measure and analyze behavioral responses of the roundworm at the holistic level, from basic motor gestures to long-term behavioral programs.

C. elegans is a well-established laboratory animal model system. Most C. elegans have only 302 neurons, few muscles and a limited repertoire of motion. A sequence of experiments involved interrupting the forward movement of individual C. elegans with a laser strike to the head. When the laser strikes a worm, it withdraws, briefly accelerating backwards and eventually returning to forward motion, usually in a different direction. Individual worms respond differently. Some, for instance, immediately reverse direction upon laser stimulus, while others pause briefly before responding. Another variable in the experiments is the intensity of the laser: Worms respond faster to hotter and more rapidly rising temperatures.

For the PNAS paper, the researchers fed the Sir Isaac platform the motion data from the first few seconds of the experiments — before and shortly after the laser strikes a worm and it initially reacts. From this limited data, the algorithm was able to capture the average responses that matched the experimental results and also to predict the motion of the worm well beyond these initial few seconds, generalizing from the limited knowledge. The prediction left only 10 percent of the variability in the worm motion that can be attributed to the laser stimulus unexplained. This was twice as good as the best prior models, which were not aided by automated inference.

“Predicting a worm’s decision about when and how to move in response to a stimulus is a lot more complicated than just calculating how a ball will move when you kick it,” Nemenman says. “Our algorithm had to account for the complexities of sensory processing in the worms, the neural activity in response to the stimuli, followed by the activation of muscles and the forces that the activated muscles generate. It summed all this up into a simple and elegant mathematical description.”

The model derived by Sir Isaac was well-matched to the biology of C. elegans, providing interpretable results for both the sensory processing and the motor response, hinting at the potential of artificial intelligence to aid in discovery of accurate and interpretable models of more complex systems.

“It’s a big step from making predictions about the behavior of a worm to that of a human,” Nemenman says, “but we hope that the worm can serve as a kind of sandbox for testing out methods of automated inference, such that Sir Isaac might one day directly benefit human health. Much of science is about guessing the laws that govern natural systems and then verifying those guesses through experiments. If we can figure out how to use modern machine learning tools to help with the guessing, that could greatly speed up research breakthroughs.”

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