DURHAM, N.C. — The Albemarle-Pamlico Peninsula covers more than 2,000 square miles on the North Carolina coastal plain, a vast expanse of forested swamps and tea-colored creeks. Many people would probably avoid this place, whose dense thickets of cane and shrubs and waterlogged soils can slow a hike to a crawl.
“It’s hard fieldwork,” says Duke researcher Steve Anderson. “It gets really dense and scratchy. That, plus the heat and humidity mixed with the smell of sulfur and the ticks and the poison ivy; it just kind of adds up.”
But to Anderson and colleagues from Duke and North Carolina State University, these bottomlands are more than impenetrable marsh and muck and mosquitoes. They’re also a barometer of change.
Most of the area they study lies a mere two to three feet above sea level, which exposes it to surges of ocean water — 400 times saltier than freshwater — driven inland by storms and rising seas. The salt deposits left behind when these waters recede build up year after year, until eventually they become too much for some plants to cope with.
Trudging in hip waders through stunted shrubs and rotting tree stumps, Anderson snaps a picture with his phone of a carpet of partridge berry trailing along the forest floor. In some parts of the peninsula, he says, the soils are becoming so salty that plants like these can no longer reproduce or are dying off entirely.
In a recent study the team, led by professors Justin Wright and Emily Bernhardt of Duke, and Marcelo Ardón of NC State, surveyed some 112 understory plants in the region, making note of where they were found and how abundant they were in relation to salt levels in the soil.
The researchers identified a ‘tipping point,’ around 265 parts per million sodium, where even tiny changes in salinity can set off disproportionately large changes in the plants that live there.
Above this critical threshold, the makeup of the marsh floor suddenly shifts, as plants such as wax myrtle, swamp bay and pennywort are taken over by rushes, reeds and other plants that can better tolerate salty soils.
The hope is that monitoring indicator species like these could help researchers spot the early warning signs of salt stress, Anderson says.
This research was supported by grants from the National Science Foundation (DEB1713435, DEB 1713502, and Coastal SEES Collaborative Research Award Grant No. 1426802).
CITATION: “Salinity Thresholds for Understory Plants in Coastal Wetlands,” Anderson, S. M., E. A. Ury, P. J. Taillie, E. A. Ungberg, C. E. Moorman, B. Poulter, M. Ardón, E. S. Bernhardt, and J. P. Wright. Plant Ecology, Nov. 24, 2021. DOI: 10.1007/s11258-021-01209-2.
Dr. Cathy Williams knew something wasn’t right. The veterinarian had felt off for weeks after her 2014 trip to Madagascar.
At first she just felt bloated and uncomfortable and wasn’t interested in eating much. But eventually she developed a fever and chills that sent her to the emergency room.
When tested, doctors found that what she had wasn’t just a stomach bug. She was suffering from an infection of Clostridium difficile, a germ that causes severe diarrhea and abdominal pain and can quickly become life-threatening if not treated promptly.
“It was horrible,” Williams said.
The condition is often triggered when antibiotics disrupt the normal balance of bacteria that inhabit the gut, allowing “bad” bacteria such as C. difficile to multiply unchecked and wreak havoc on the intestines.
To get her infection under control, Williams asked her doctors if they could try an approach she and other veterinarians had used for decades to treat lemurs with digestive problems at the Duke Lemur Center. The procedure, known as a fecal microbiota transplant, involves taking stool from a healthy donor and administering it to the patient to add back “good” microbes and reset the gut.
At the time it was considered too experimental for clinical use in human cases like Williams’. She was prescribed the standard treatment and was sent home from the hospital, though she wouldn’t feel well enough to go back to work for another month. But now new research in lemurs is confirming what Williams and others long suspected: that this ancient if gross-sounding treatment can help an off-kilter gut microbiome get back to normal.
In a recent study in the journal Animal Microbiome, a research team led by Duke professor Christine Drea, former PhD student Sally Bornbusch and colleagues looked at the gut microbiomes of 11 healthy ring-tailed lemurs over a four-month period after receiving a seven-day course of the broad-spectrum antibiotic amoxicillin.
The lemurs were split into two experimental groups. One was a wait-and-see group, with continued follow-up but no further treatment after the antibiotics. The other group was given a slurry of their own feces, collected prior to antibiotic treatment and then mixed with saline and fed back to the same animal after their course of antibiotics was over.
“It sounds crazy,” Williams said. But she has used a similar procedure since the 1990s to treat illnesses in Coquerel’s sifaka lemurs, whose infants are known to eat their mother’s poop during weaning — presumably to get the microbes they’ll need to transition to solid food.
Drea, Bornbusch and team used genetic sequencing techniques to track changes in the lemurs’ gut microbiome before, during and after treatment.
As expected, even a single course of antibiotics caused the numbers of microbes in their guts to plunge compared with controls, briefly wiping out species diversity in both experimental groups before returning to baseline.
“Antibiotics had dramatic effects, even in healthy animals,” Drea said.
But in terms of which types of bacteria bounced back and when, the patterns of recovery in the two groups were different. Lemurs that received the “poop soup” treatment started to stabilize and return to their pre-antibiotic microbiome within about two weeks. In contrast, the bacterial composition in the wait-and-see group continued to fluctuate, and still hadn’t quite returned to normal even after four months of observation.
This kind of therapy isn’t new. Reports of using fecal transplants to treat people suffering from food poisoning or diarrhea date back as far as fourth century China. The evidence for its effectiveness in captive settings has Bornbusch advocating for freezing stool at Smithsonian’s National Zoo, where she is now a postdoctoral fellow.
“If we can bank feces from animals when they’re healthy, that can be a huge benefit down the road,” Bornbusch said. “It can help the animals get better, faster.”
And now if any of her lemur patients were to get sick with C. difficile like she did, Williams said, “I would absolutely go with a fecal microbiota transplant.”
“People are put off by it,” Drea said, “But the disgust for this approach might actually have been holding up a fairly cheap and useful cure.”
This research was supported by the National Science Foundation (BCS 1749465), the Duke Lemur Center Director’s Fund, and the Duke Microbiome Center.
CITATION: “Antibiotics and Fecal Transfaunation Differentially Affect Microbiota Recovery, Associations, and Antibiotic Resistance in Lemur Guts,” Sally L. Bornbusch, Rachel L. Harris, Nicholas M. Grebe, Kimberly Roche, Kristin Dimac-Stohl, Christine M. Drea. Animal Microbiome, Oct. 1, 2021. DOI: 10.1186/s42523-021-00126-z.
DNA extracted from a 1,475-year-old jawbone reveals genetic blueprint for one of the largest lemurs ever.
If you’ve been to the Duke Lemur Center, perhaps you’ve seen these cute mouse- to cat-sized primates leaping through the trees. Now imagine a lemur as big as a gorilla, lumbering its way through the forest as it munches on leaves.
It may sound like a scene from a science fiction thriller, but from skeletal remains we know that at least 17 supersized lemurs once roamed the African island of Madagascar. All of them were two to 20 times heftier than the average lemur living today, some weighing up to 350 pounds.
Then, sometime after humans arrived on the island, these creatures started disappearing.
The reasons for their extinction remain a mystery, but by 500 years ago all of them had vanished.
Coaxing molecular clues to their lives from the bones and teeth they left behind has proved a struggle, because after all this time their DNA is so degraded.
But now, thanks to advances in our ability to read ancient DNA, a giant lemur that may have fallen into a cave or sinkhole near the island’s southern coast nearly 1,500 years ago has had much of its DNA pieced together again. Researchers believe it was a slow-moving 200-pound vegetarian with a pig-like snout, long arms, and powerful grasping feet for hanging upside down from branches.
A single jawbone, stored at Madagascar’s University of Antananarivo, was all the researchers had. But that contained enough traces of DNA for a team led by George Perry and Stephanie Marciniak at Penn State to reconstruct the nuclear genome for one of the largest giant lemurs, Megaladapis edwardsi, a koala lemur from Madagascar.
Ancient DNA can tell stories about species that have long since vanished, such as how they lived and what they were related to. But sequencing DNA from partially fossilized remains is no small feat, because DNA breaks down over time. And because the DNA is no longer intact, researchers have to take these fragments and figure out their correct order, like the pieces of a mystery jigsaw puzzle with no image on the box.
Hard-won history lessons
The first genetic study of M. edwardsi, published in 2005 by Duke’s Anne Yoder, was based on DNA stored not in the nucleus — which houses most of our genes — but in another cellular compartment called the mitochondria that has its own genetic material. Mitochondria are plentiful in animal cells, which makes it easier to find their DNA.
At the time, ancient DNA researchers considered themselves lucky to get just a few hundred letters of an extinct animal’s genetic code. In the latest study they managed to tease out and reconstruct some one million of them.
“I never even dreamed that the day would come that we could produce whole genomes,” said Yoder, who has been studying ancient DNA in extinct lemurs for over 20 years and is a co-author of the current paper.
For the latest study, the researchers tried to extract DNA from hundreds of giant lemur specimens, but only one yielded enough useful material to reconstitute the whole genome.
Once the creature’s genome was sequenced, the team was able to compare it to the genomes of 47 other living vertebrate species, including five modern lemurs, to identify its closest living relatives. Its genetic similarities with other herbivores suggest it was well adapted for grazing on leaves.
Despite their nickname, koala lemurs weren’t even remotely related to koalas. Their DNA confirms that they belonged to the same evolutionary lineage as lemurs living today.
To Yoder it’s another piece of evidence that the ancestors of today’s lemurs colonized Madagascar in a single wave.
Since the first ancient DNA studies were published, in the 1980s, scientists have unveiled complete nuclear genomes for other long-lost species, including the woolly mammoth, the passenger pigeon, and even extinct human relatives such as Neanderthals.
Most of these species lived in cooler, drier climates where ancient DNA is better preserved. But this study extends the possibilities of ancient DNA research for our distant primate relatives that lived in the tropics, where exposure to heat, sunlight and humidity can cause DNA to break down faster.
“Tropical conditions are death to DNA,” Yoder said. “It’s so exciting to get a deeper glimpse into what these animals were doing and have that validated and verified.”
See them for yourself
Assembled in drawers and cabinets cases in the Duke Lemur Center’s Division of Fossil Primates on Broad St. are the remains of at least eight species of giant lemurs that you can no longer find in the wild. If you live in Durham, you may drive by them every day and have no idea. It’s the world’s largest collection.
In one case are partially fossilized bits of jaws, skulls and leg bones from Madagascar’s extinct koala lemurs. Nearby are the remains of the monkey-like Archaeolemur edwardsi, which was once widespread across the island. There’s even a complete skeleton of a sloth lemur that would have weighed in at nearly 80 pounds, Palaeopropithecus kelyus, hanging upside down from a branch.
Most of these specimens were collected over 25 years between 1983 and 2008, when Duke Lemur Center teams went to Madagascar to collect fossils from caves and ancient swamps across the island.
“What is really exciting about getting better and better genetic data from the subfossils, is we may discover more genetically distinct species than only the fossil record can reveal,” said Duke paleontologist Matt Borths, who curates the collection. “That in turn may help us better understand how many species were lost in the recent past.”
They plan to return in 2022. “Hopefully there is more Megaladapis to discover,” Borths said.
CITATION: “Evolutionary and Phylogenetic Insights From a Nuclear Genome Sequence of the Extinct, Giant, ‘Subfossil’ Koala Lemur Megaladapis Edwardsi,” Stephanie Marciniak, Mehreen R. Mughal, Laurie R. Godfrey, Richard J. Bankoff, Heritiana Randrianatoandro, Brooke E. Crowley, Christina M. Bergey, Kathleen M. Muldoon, Jeannot Randrianasy, Brigitte M. Raharivololona, Stephan C. Schuster, Ripan S. Malhi, Anne D. Yoder, Edward E. Louis Jr, Logan Kistler, and George H. Perry. PNAS, June 29, 2021. DOI: 10.1073/pnas.2022117118.
Herman Pontzer explains where our calories really go, and what studying humanity’s past can teach us about staying healthy today.
Duke professor Herman Pontzer has spent his career counting calories. Not because he’s watching his waistline, exactly. But because, as he sees it, “in the economics of life, calories are the currency.” Every minute, everything the body does — growing, moving, fighting infection, even just existing — “all of it takes energy,” Pontzer says.
In his new book, “Burn,” the evolutionary anthropologist recounts the 10-plus years he and his colleagues have spent measuring the metabolisms of people ranging from ultra-athletes to office workers, as well as those of our closest animal relatives, and some of the surprising insights the research has revealed along the way.
Much of his work takes him to Tanzania, where members of the Hadza tribe still get their food the way our ancestors did — by hunting and gathering. By setting out on foot each day to hunt zebra and antelope or forage for berries and tubers, without guns or electricity or domesticated animals to lighten the load, the Hadza get more physical activity each day than most Westerners get in a week.
So they must burn more calories, right? Wrong.
Pontzer and his colleagues have found that, despite their high activity levels, the Hadza don’t burn more energy per day than sedentary people in the U.S. and Europe.
These and other recent findings are changing the way we understand the links between energy expenditure, exercise and diet. For example, we’ve all been told that if we want to burn more calories and fight fat, we need to work out to boost our metabolism. But Pontzer says it’s not so simple.
“Our metabolic engines were not crafted by millions of years of evolution to guarantee a beach-ready bikini body,” Pontzer says. But rather, our metabolism has been primed “to pack on more fat than any other ape.” What’s more, our metabolism responds to changes in exercise and diet in ways that thwart our efforts to shed pounds.
What this means, Pontzer says, is you can walk 16,000 steps each day like the Hadza and you won’t lose weight. Sure, if you run a marathon tomorrow you’ll burn more energy than you did today. But over time, metabolism responds to changes in activity to keep the total energy you spend in check.
Pontzer’s book is more than a romp through the Krebs cycle. For anyone suffering pandemic-induced pangs of frustrated wanderlust, it’s also filled with adventure. He takes readers on an hours-long trek to watch a Hadza man track a wounded giraffe across the savannah, to the rainforests of Uganda to study climbing chimpanzees, and to the foothills of the Caucasus Mountains to unearth the 1.8 million-year-old remains of some of the first people who trekked out of Africa.
His humor shines through along the way. Even when awoken by a chorus of 300-pound lions just a few hundred yards from his tent, he stops to ponder whether his own stench gives him away, and what he might do if they come for his “soft American carcass, the warm triple crème brie of human flesh.”
Pontzer spoke via email with Duke Today about his book:
Q: What’s the lesson the Hadza and other hunter-gatherers teach us about managing weight and staying healthy?
A: The Hadza stay incredibly fit and healthy throughout their lives, even into their older ages (60’s, 70’s, even 80’s). They don’t develop heart disease, diabetes, obesity, or the other diseases that we in the industrialized world are most likely to suffer from. They also have an incredibly active lifestyle, getting more physical activity in a typical day than most Americans get in a week.
My work with the Hadza showed that, surprisingly, even though they are so physically active, Hadza men and women burn the same number of calories each day as men and women in the U.S. and other industrialized countries. Instead of increasing the calories burned per day, the Hadza physical activity was changing the way they spend their calories — more on activity, less on other, unseen tasks in the body.
The takeaway for us here in the industrialized world is that we need to stay active to stay healthy, but we can’t count on exercise to increase our daily calorie burn. Our bodies adjust, keeping energy expenditure in a narrow range regardless of lifestyle. And that means that we need to focus on diet and the calories we consume in order to manage our weight. At the end of the day, our weight is a matter of calories eaten versus calories burned — and it’s really hard to change the calories we burn!
Q: You’re saying that exercise doesn’t matter? What’s the point, if we can’t eat that donut?
A: All those adjustments our bodies make responding to exercise are really important for our health! When we burn more calories on exercise, our bodies spend less energy on inflammation, stress reactivity (like cortisol), and other things that make us sick.
Q: What’s the biggest misunderstanding about human metabolism?
A: We’re told — through fitness magazines, diet fads, online calorie counters — that the energy we burn each day is under our control: if we exercise more, we’ll burn more calories and burn off fat. It’s not that simple! Your body is a clever, dynamic product of evolution, shifting and adapting to changes in our lifestyle.
Q: In your book you say we’re driven to magical thinking when it comes to calories. What do you mean by that?
A: Because our body is so clever and dynamic, and because humans are just bad at keeping track of what we eat, it’s awfully hard to keep track of the calories we consume and burn each day. That, along with the proliferation of fad diets and get-thin-quick schemes, has led to this idea that “calories don’t matter.” That’s magical thinking. Every ounce of your body — including every calorie of fat you carry — is food you consumed and didn’t burn off. If we want to lose weight, we must eat fewer calories than we burn. It really comes down to that.
Q: Some people say that if the cavemen didn’t eat it, we shouldn’t either. What does research show about what foods are “natural” for humans to eat?
A: There’s no singular, natural human diet. Hunter-gatherers like the Hadza eat a diverse mix of plant and animal foods that varies day to day, month to month, and year to year. There’s even more dietary diversity when we look across populations. Humans are built to thrive on a wide variety of diets — just about everything is on the menu.
That said, the ultra-processed foods we’re inundated with in our modern industrialized world really are unnatural. There are no Twinkies to forage in the wild. Those foods are literally engineered to be overconsumed, with a mix of flavors that overwhelm our brain’s ability to regulate our appetites. Now, it is still possible to lose weight on a Twinkie diet (I’m not recommending it!), if you’re very strict about the calories eaten per day. But we need to be really careful about how we incorporate ultra-processed foods into our daily diets, because they are calorie bombs that drive us to overconsume.
Q: If we could time travel, what would our hunter-gatherer ancestors make of our industrialized diet today?
A: We don’t even need to imagine — We are those hunter-gatherers! Biologically, genetically, we are the same species that we were a hundred thousand years ago, when hunting and gathering were the only game in town. When we’re confronted with modern ultra-processed foods, we struggle. They are engineered to be delicious, and we tend to overconsume.
Q: Has the COVID-19 pandemic brought any of these lessons home for you? What can we do to keep active and watch what we eat, even while working from home?
The pandemic has been a tragedy on so many levels — the loss of life, those suffering with long-term effects, the social and economic impacts. The impact on diet and exercise have been bad as well, for many of us. Stress eating is a real phenomenon, and the stress and emotional toll of the pandemic — along with having easy access to the snacks in our kitchen — have led many to gain weight. Physical activity seems to have declined for many. There aren’t easy answers, but we should try to make a point to get active every day. And we can help ourselves make better decisions about food by keeping ultra-processed foods out of our houses. You can’t plow through a bag of chips if you don’t have chips in your cupboard.
Q: You’ve measured the energy costs of activities ranging from taking a breath to doing an Ironman. What is one of the more extreme or surprising calorie-burning activities that you’ve measured, or would like to measure, in humans or some other animal?
A: With colleagues from Japan, I measured the energy cost of a heartbeat – a tricky bit of metabolic measurement! Turns out each beat of your heart burns about 1/300th of a kilocalorie! Amazing how efficient our bodies can be.
Q: What is something people have questions about that we just don’t know the answer to yet? What would it take to find out?
A: Right now we’re excited about measuring the adjustments our bodies make when we increase our exercise: how exactly does burning more energy on physical activity impact our immune system, our stress response, our reproductive system? It will take a long-term study of exercise to see how these systems change over time.
This squiggly line shows the path taken by a snippet of DNA as it might move around within the soupy interior of a cell. Duke’s Kevin Welsher and colleagues have developed a technique that turns a microscope into a ‘flight tracker’ for molecules, making it possible to follow the paths of viruses and other particles thousands of times smaller than the period at the end of this sentence. Until now, such techniques have required particles to be tethered to make sure they stay within the field of view. But the Welsher lab has developed a way to lock on to freely moving targets and track them for minutes at a time.
It was a Frankenstein moment for Duke alumnus and adjunct physics professor Henry Everitt.
After years of working out the basic
principles behind his new laser, last Halloween he was finally ready to put it
to the test. He turned some knobs and toggled some switches, and presto, the
first bright beam came shooting out.
“It was like, ‘It’s alive!’” Everitt said.
This was no laser for presenting Powerpoint slides or entertaining cats. Everitt and colleagues have invented a new type of laser that emits beams of light in the ‘terahertz gap,’ the no-man’s-land of the electromagnetic spectrum between microwaves and infrared light.
Terahertz radiation, or ‘T-rays,’ can see
through clothing and packaging, but without the health hazards of harmful
radiation, so they could be used in security scanners to spot concealed weapons
without subjecting people to the dangers of X-rays.
It’s also possible to identify substances by
the characteristic frequencies they absorb when T-rays hit them, which makes
terahertz waves ideal for detecting toxins in the air or gases between the
stars. And because such frequencies are higher than those of radio waves and
microwaves, they can carry more bandwidth, so terahertz signals could transmit
data many times faster than today’s cellular or Wi-Fi networks.
“Imagine a wireless hotspot where you could
download a movie to your phone in a fraction of a second,” Everitt said.
Yet despite the potential payoffs, T-rays
aren’t widely used because there isn’t a portable, cheap or easy way to make
Now Everitt and colleagues at Harvard University and MIT have invented a small, tunable T-ray laser that might help scientists tap into the terahertz band’s potential.
While most terahertz molecular lasers take up
an area the size of a ping pong table, the new device could fit in a shoebox.
And while previous sources emit light at just one or a few select frequencies,
their laser could be tuned to emit over the entire terahertz spectrum, from 0.1
to 10 THz.
The laser’s tunability gives it another
practical advantage, researchers say: the ability to adjust how far the T-ray
beam travels. Terahertz signals don’t go very far because water vapor in the
air absorbs them. But because some terahertz frequencies are more strongly
absorbed by the atmosphere than others, the tuning capability of the new laser
makes it possible to control how far the waves travel simply by changing the
frequency. This might be ideal for applications like keeping car radar sensors
from interfering with each other, or restricting wireless signals to short
distances so potential eavesdroppers can’t intercept them and listen in.
Everitt and a team co-led by Federico Capasso of Harvard and Steven Johnson of MIT describe their approach this week in the journal Science. The device works by harnessing discrete shifts in the energy levels of spinning gas molecules when they’re hit by another laser emitting infrared light.
Their T-ray laser consists of a pencil-sized
copper tube filled with gas, and a 1-millimeter pinhole at one end. A zap from the
infrared laser excites the gas molecules within, and when the molecules in this
higher energy state outnumber the ones in a lower one, they emit T-rays.
The team dubbed their gizmo the “laughing gas
laser” because it uses nitrous oxide, though almost any gas could work, they
Everitt started working on terahertz laser designs 35 years ago as a Duke undergraduate in the mid-1980s, when a physics professor named Frank De Lucia offered him a summer job.
De Lucia was interested in improving special
lasers called “OPFIR lasers,” which were the most powerful sources of T-rays at
the time. They were too bulky for widespread use, and they relied on an equally
unwieldy infrared laser called a CO2 laser to excite the gas inside.
Everitt was tasked with trying to generate
T-rays with smaller gas laser designs. A summer gig soon grew into an
undergraduate honors thesis, and eventually a Ph.D. from Duke, during which he
and De Lucia managed to shrink the footprint of their OPFIR lasers from the
size of an axe handle to the size of a toothpick.
But the CO2 lasers they were
partnered with were still quite cumbersome and dangerous, and each time
researchers wanted to produce a different frequency they needed to use a different
gas. When more compact and tunable sources of T-rays came to be, OPFIR lasers
were largely abandoned.
Everitt would shelf the idea for another
decade before a better alternative to the CO2 laser came along, a
compact infrared laser invented by Harvard’s Capasso that could be
tuned to any frequency over a swath of the infrared spectrum.
By replacing the CO2 laser with
Capasso’s laser, Everitt realized they wouldn’t need to change the laser gas anymore
to change the frequency. He thought the OPFIR laser approach could make a
comeback. So he partnered with Johnson’s team at MIT to work out the theory,
then with Capasso’s group to give it a shot.
The team has moved to patent their design,
but there is still a long way before it finds its way onto store shelves or
into consumers’ hands. Nonetheless, the researchers — who couldn’t resist a
laser joke — say the outlook for the technique is “very bright.”
This research was supported by the U.S. Army Research Office (W911NF-19-2-0168, W911NF-13-D-0001) and by the National Science Foundation (ECCS-1614631) and its Materials Research Science and Engineering Center Program (DMR-1419807).
CITATION: “Widely Tunable Compact Terahertz Gas Lasers,” Paul Chevalier, Arman Armizhan, Fan Wang, Marco Piccardo, Steven G. Johnson, Federico Capasso, Henry Everitt. Science, Nov. 15, 2019. DOI: 10.1126/science.aay8683.
Thomas Barlow ’21 finds inspiration in small everyday things most people overlook: a craggy lichen growing on a tree, a dead insect, the light reflected by a pane of glass. Where we might see a flower, Barlow looks past the showy pink petals to the intricate parts tucked within.
The 20-year-old is a Duke student majoring in biology. By day, he takes classes and does research in a lab. But in his spare time, he likes to take up-close photographs using objects he finds outside or around the lab: peach pits, fireflies. But also pipettes, pencils.
Barlow got interested in photography in middle school, while playing around with his dad’s camera. His dad, a landscape architect, encouraged the hobby by enlisting him to take photos of public parks, gardens and playgrounds, which have been featured on various architects’ websites and in national publications such as Architecture Magazine. But “I always wanted to get closer, to see more,” Barlow said.
In high school he started taking pictures of still lifes. But he didn’t just throw flowers and fruit onto a backdrop and call it art. His compositions were a mishmash of insects and plants arranged with research gadgets: glass tubes, plastic rulers, syringes, or silicon wafers like those used for computer chips.
“I like pairing objects you would never find
together normally,” Barlow said. “Removing them from their context and
generating images with interesting textures and light.”
Sometimes his mother sends him treasures from her garden in Connecticut to photograph, like the pale green wings of a luna moth. But mostly he finds his subjects just steps from his dorm room door. It might be as easy as taking a walk through Duke Gardens or going for one of his regular runs in Duke Forest.
Having found, say, a flower bud or bumblebee, he then uses bits of glass, metal, mirrors and other shiny surfaces — “all objects that interact with light in some interesting way” – to highlight the interaction of light and color.
“I used to be really obsessed with dichroic
mirrors,” pieces of glass that appear to change colors when viewed from
different angles, Barlow said. “I thought they were beautiful objects. You can
get so many colors and reflections out of it, just by looking at it in
In one pair of images, the white,
five-petaled flowers of a meadow anemone are juxtaposed against panels of
frosted glass, a pipette, a mechanical pencil.
Another image pair shows moth wings. One is zoomed in to capture the fine details of the wing scales. The other zooms out to show them scattered willy-nilly around a shimmering pink circle of glass, like the remnants of a bat’s dinner plate.
For extreme close-ups, Barlow uses his Canon
DSLR with a microscope objective mounted onto the front of a tube lens.
Shooting this close to something so small isn’t just a matter of putting a bug
or flower in front of the camera and taking a shot. To get every detail in
focus, he takes multiple images of the same subject, moving the focal point
each time. When he’s done he’s taken hundreds of pictures, each with a
different part of the object in focus. Then he merges them all together.
At high magnification, Barlow’s flower close-ups reveal the curly yellow stamens of a zinnia flower, and the deep red pollen-producing parts of a tiger lily.
“I love that you can see the spikey pollen
globules,” Barlow said.
When he first got to Duke he was taking photos using a DIY setup in his dorm room. Then he asked some of the researchers and faculty he knew if there was anything photography-related he could do for their labs.
“I knew I was interested in nature
photography and I wanted to practice it,” Barlow said.
One thing led to another, and before long he
moved his setup to the Biological Sciences building on Science Drive, where he’s
been photographing lichens for Daniele Armaleo and Jolanta Miadlikowska, both
“A lichen photo might not seem like anything special to an average person,” Barlow said. “But I think they’re really stunning.”
finish among top 1% in 100-hour math modeling contest against 11,000 teams
If you’ve ever visited the Louvre in Paris, you may have been too focused on snapping a selfie in front of the Mona Lisa to think about the nearest exit.
But one Duke team knows how to get out fast when it matters most, thanks to a computer simulation they developed for the Interdisciplinary Contest in Modeling, an international contest in which thousands of student teams participate each year.
Their results, published in the
Journal of Undergraduate Mathematics and Its Applications, placed them in the
top 1% against more than 11,000 teams worldwide.
With a record 10.2 million visitors
flooding through its doors last year, the Louvre is one of the most popular
museums in the world. Just walking through a single wing in one of its five
floors can mean schlepping the equivalent of four and a half football fields.
For the contest, Duke undergraduates
Vinit Ranjan, Junmo Ryang and Albert Xue had four days to figure out how long
it would take to clear out the whole building if the museum really had to evacuate
— if the fire alarm went off, for instance, or a bomb threat or a terror
attack sent people pouring out of the building.
It might sound like a grim premise.
But with a rise in terrorist activity in Europe in recent years, facilities are
trying to plan ahead to get people to safety.
The team used a computer program
called NetLogo to create a small simulated Louvre populated by 26,000 visitors,
the average number of people to wander through the maze of galleries each day.
They split each floor of the Louvre into five sections, and assigned people to
follow the shortest path to the nearest exit unless directed otherwise.
Their model uses simple flow rates — the number of people that can “flow” through an exit per second — and average walking speeds to calculate evacuation times. It also lets users see what happens to evacuation times if some evacuees are disabled, or can’t push through the throngs and start to panic.
If their predictions are right, the
team says it should be possible to clear everyone out in just over 24 minutes.
Their results show that the exit at
the Passage Richelieu is critical to evacuation — if that exit is blocked, the
main exit through the Pyramid would start to gridlock and evacuating would take
a whopping 15 minutes longer.
The students also identified several
narrow corridors and sharp turns in the museum’s ground floor that could
contribute to traffic jams. Their analyses suggest that widening some of these
bottlenecks, or redirecting people around them, or adding another exit door
where evacuees start to pile up, could reduce the time it takes to evacuate by
For the contest, each team of three
had to choose a problem, build a model to solve it, and write a 20-page paper
describing their approach, all in less than 100 hours.
“It’s a slog fest,” Ranjan said. “In
the final 48 hours I think I slept a total of 90 minutes.”
Duke professor emeritus David Kraines, who advised the team, says the students were the first Duke team in over 10 years to be ranked “outstanding,” one of only 19 out of the more than 11,200 competing teams to do so this year. The team was also awarded the Euler Award, which comes with a $9000 scholarship to be split among the team members.
Many people turn to the Internet to find a Mr. or Ms. Right. But lemurs don’t have to cyberstalk potential love interests to find a good match — they just give them a sniff.
A study of lemur scents finds that an individual’s distinctive body odor reflects genetic differences in their immune system, and that other lemurs can detect these differences by smell.
From just one whiff, these primates are able to tell which prospective partners have immune genes different from their own. The ability to sniff out mates with different immune genes could make their offspring’s immune systems more diverse and able to fight more pathogens, said first author Kathleen Grogan, who did the research while working on her Ph.D. with professor Christine Drea at Duke University.
The results appeared online August 22 in the journal BMC Evolutionary Biology.
Lemurs advertise their presence by scent marking — rubbing stinky glands against trees to broadcast information about their sex, kin, and whether they are ready to mate.
For the study, Grogan, Drea and colleagues collected scent secretions from roughly 60 lemurs at the Duke Lemur Center, the Indianapolis Zoo, and the Cincinnati Zoo. The team used a technique called gas chromatography-mass spectrometry to tease out the hundreds of compounds that make up each animal’s signature scent.
They also analyzed the lemurs’ DNA, looking for differences within a cluster of genes called MHC that help trigger the body’s defenses against foreign invaders such as bacteria and viruses.
Their tests reveal that the chemical cocktail lemurs emit varies depending on which MHC types they carry.
To see if potential mates can smell
the difference, the researchers presented lemurs with pairs of wooden rods
smeared with the bodily secretions of two unfamiliar mates and observed their
responses. Within seconds, the animals were drawn to the smells wafting from
the rods, engaging in a frenzy of licking, sniffing, or rubbing their own
scents on top.
In 300 trials, the team found that
females paid more attention to the scents of males whose immune genes differed
from their own.
MHC genes code for proteins that help the immune system recognize foreign invaders and distinguish “friend” from “foe.” Since different genetic versions respond to different sets of foreign substances, Grogan said, sniffing out genetically dissimilar mates produces offspring more capable of fighting a broad range of pathogens.
Just because females spent more time
checking out the scents of dissimilar males doesn’t necessarily make them more
likely to have kids together, Grogan said. Moving forward, she and her
colleagues plan to use maternity and paternity DNA test results from wild
lemurs living in Beza Mahafaly Reserve in Madagascar to see if lemur couples
are more different in their MHC type than would be expected by chance.
Similar results have been found in humans, but this is the first time the ability to sniff out partners based on their immune genes has been shown in such distant primate kin, said Grogan, who is currently a postdoctoral fellow at Pennsylvania State University.
“Growing evidence suggests that
primates rely on olfactory cues way more than we thought they did,” Grogan
said. “It’s possible that all primates can do this.”
This research was supported by the National Science Foundation (BCS #0409367, IOS #0719003), the National Institutes of Health (F32 GM123634–01), and the Duke University Center for Science Education.
CITATION: “Genetic Variation at MHC class II Loci Influences Both Olfactory Signals and Scent Discrimination in Ring-Tailed Lemurs,” Kathleen E. Grogan, Rachel L. Harris, Marylène Boulet, and Christine M. Drea. BMC Evolutionary Biology, August 22, 2019. DOI: 10.1186/s12862-019-1486-0
This is what 20 years of evictions looks like. It’s an animated heat map of Durham, the streets overlaid with undulating blobs of red and orange and yellow, like a grease stain.
Duke students in the summer research program Data+ have created a time-lapse map of the more than 200,000 evictions filed in Durham County since 2000.
Dark red areas represent eviction hotspots. These neighborhoods are where families cook their favorite meals, where children do their homework, where people celebrate holidays. They’re also where many people live one crisis away from losing their neighbors, or becoming homeless themselves.
Duke junior Samantha Miezio points to a single census tract along NC 55 where, in the wake of an apartment building sale, more than 100 households received an eviction notice in that spot in one month alone. It “just speaks to the severity of the issue,” Miezio said.
Miezio was part of a team that spent 10 weeks this summer mapping and analyzing evictions data from the Durham County Sheriff’s Office, thanks to an effort by DataWorks NC to compile such data and make it more accessible.
The findings are stark.
Every hour in Durham, at least one
renter is threatened with losing their home. About 1,000 eviction cases were
filed a month against tenants between 2010 and 2017. That’s roughly one for every
280 residents in Durham, where evictions per capita is one of the highest in the state and double the national
The data tell us that while Durham’s
evictions crisis has actually improved from where it was a few years ago,
stubborn hotspots persist, said team member Ellis Ackerman, a math major at
North Carolina State University.
When the students looked at the data
month by month, a few things stood out. For one, winter evictions are common.
While some countries such as France and Austria ban winter evictions to
keep from pushing people onto the street in the cold, in Durham, “January is
the worst month by far,” said team member Rodrigo Araujo, a junior majoring
in computer science. “In the winter months utility bills are higher; they’re
struggling to pay for that.”
The team also investigated the relationship between evictions and rents from 2012 to 2014 to see how much they move in tandem with each other. Their initial results using two years’ worth of rent data showed that when rents went up, evictions weren’t too far behind.
“Rents increased, and then two months later,
evictions increased,” Miezio said.
But the impacts of rising rents weren’t felt evenly. Neighborhoods with more residents of color were significantly affected while renters in white neighborhoods were not. “This crisis is disproportionately affecting those who are already at a disadvantage from historical inequalities,” Miezio said.
A person can be evicted for a number of reasons, but most evictions happen because people get behind on their rent. The standard guideline is no more than 30% of your monthly income before taxes should go to housing and keeping the lights on.
But in Durham, where 47% of households
rent rather than own a home, only half of renters meet that goal. As
of 2019 an estimated 28,917 households are living in rentals they can’t afford.
The reason is incomes haven’t kept
pace with rents, especially for low-wage workers such as waiters, cooks, or
home health aides.
Durham’s median rents rose from $798 in 2010 to $925 in 2016. That’s out of reach for many area families. A minimum wage worker in Durham earning $7.25/hour would need to work a staggering 112 hours a week — the equivalent of nearly three full-time jobs — to afford a modest two-bedroom unit in 2019 at fair market rent, according to a report by the National Low Income Housing Coalition.
Spending a sizable chunk of your
income on housing means having less left over for food, child care,
transportation, savings, and other basic necessities. One unexpected expense or
emergency — maybe the kid gets sick or the car needs repairs, or there’s a cut
back on hours at work — can mean tenants have a harder time making the rent.
“Evictions are traumatic life
experiences for the tenants,” and can have ripple effects for years, Miezio
Tenants may have only a few days to
pay what’s due or find a new place and move out. The Sheriff may come with
movers and pile a person’s belonging on the curb, or move them to a storage
facility at the tenant’s expense.
A forced move can also mean children
must change schools in the middle of the school year.
Benefits may go to the wrong address.
Families are uprooted from their social support networks of friends and
Not every case filed ends with the
tenant actually getting forced out, “but those filings can still potentially
inhibit their ability to find future housing,” Miezio said. Not to mention the
cost and hassle of appearing in court and paying fines and court fees.
Multiple groups are working to help
Durham residents avoid eviction and stay in their homes. In a partnership
between Duke Law and Legal Aid of North Carolina, the Civil Justice Clinic’s
Diversion Program provides free legal assistance to people who are facing
“The majority of people who have an
eviction filed against them don’t have access to an attorney,” Miezio said.
In a cost-benefit analysis, the team’s
models suggest that “with a pretty small increase in funding to reduce
evictions, on the order of $100,000 to $150,000, Durham could be saving
millions of dollars” in the form of reduced shelter costs, hospital costs, plus
savings on mental health services other social services, Ackerman said.
Moving forward, they’re launching a website in order to share their findings. “I’ve learned HTML and CSS this summer,” said Miezio, who is pursuing an individualized degree program in urban studies. “That’s one of the things I love about Data+. I’m getting paid to learn.”
Miezio plans to continue the project
this fall through an independent study course focused on policy solutions to
evictions, such as universal right to counsel.
“Housing access and stability are important to Durham,” said Duke’s vice president for Durham affairs Stelfanie Williams. “Applied research projects such as this, reflecting a partnership between the university and community, are opportunities for students to ‘learn by doing’ and to collaborate with community leaders on problem-solving.”
Data+ 2019 is sponsored by Bass Connections, the Rhodes Information Initiative at Duke, the Social Science Research Institute, the Duke Energy Initiative, and the departments of Mathematics and Statistical Science.
Other Duke sponsors include DTECH, Science, Law, and Policy Lab, Duke Health, Duke University Libraries, Sanford School of Public Policy, Nicholas School of the Environment, Duke Global Health Institute, Development and Alumni Affairs, the Duke River Center, Representing Migrations Humanities Lab, Energy Initiative, Franklin Humanities Institute, Duke Forge, the K-Lab, Duke Clinical Research, Office for Information Technology and the Office of the Provost, as well as the departments of Electrical & Computer Engineering, Computer Science, Biomedical Engineering, Biostatistics & Bioinformatics and Biology.
Government funding comes from the National Science Foundation. Outside funding comes from Exxon Mobil, the International Institute for Sustainable Development (IISD), Global Financial Markets Center, and Tether Energy.