Following the people and events that make up the research community at Duke

Students exploring the Innovation Co-Lab

Author: Robin Smith Page 1 of 8

Duke Mathletes Stand Out in a Crowd

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Standing out in a crowd of competitors is no easy task. But one Duke team has done just that — in math.

The Blue Devils were the only U.S.-based team to claim a top 25 finish at the 40th annual Mathematical Contest in Modeling (MCM), beating out more than 18,500 other teams from 20 countries.

Blue Devils Brandon Lu, Benny Sun and Chris Kan (L to R) finished in the top 25 out of 18,525 teams in an international math contest called Mathematical Contest in Modeling.

The team consisted of undergraduates Christopher Kan, Benny Sun, and Brandon Lu. Their task: to solve a real-world problem using mathematical modeling within 96 hours.

This year’s contestants tackled problems ranging from analyzing what gives tennis players an edge at Wimbledon, to optimizing search and rescue operations for missing submersibles.

The Duke team tackled a challenge that has vexed the fishing industry in the Great Lakes: predicting the impact of an invasive parasitic fish called the sea lamprey that can wreak havoc on native fish.

By adapting existing models from biology and biochemistry to model the sea lamprey population, the students were able to determine how to best apply treatments to rid streams of these parasites.

Two sea lampreys chewing their way into the flesh of a native lake trout of the Great Lakes. (Great Lakes Fisheries Commission)

The contest “is much more open-ended and creatively-focused than most STEM classes,” said Sun, a mathematics and computer science double major at Duke.

The participants try out different approaches to modeling the problems, and there is no one correct answer.

Sun, Kan and Lu also received the Mathematical Association of America Award for their paper. “They did a great job,” said team advisor Veronica Ciocanel, an assistant professor of math and biology who also co-organizes a local version of the contest each fall, called the Triangle Competition in Math Modeling.

In these contests, creativity, time management and writing skills are just as important as cramming on concepts.

“We realized that communication was as important as the findings themselves,” Sun said. “We spent the last two days primarily focused on writing a good paper.”

Having fun as a team is important too, Sun said. “Team chemistry can be an especially important factor in success when you are all locked in the same room for the weekend.”

Robin Smith
By Robin Smith

Wiring the Brain

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From tiny flies, Duke researchers are finding new clues to how the brain sets up its circuitry.

In her time at Duke, Khanh Vien figures she’s dissected close to 10,000 fly brains. For her PhD she spent up to eight hours each day peering at baby flies under the microscope, teasing out tiny brains a fraction the size of a poppy seed.

“I find it very meditative,” she said.

Vien acknowledges that, to most people, fruit flies are little more than a kitchen nuisance; something to swat away. But to researchers like her, they hold clues to how animal brains — including our own — are built.

While the human brain has some 86 billion neurons, a baby fruit fly’s brain has a mere 3016 — making it millions of times simpler. Those neurons talk to each other via long wire-like extensions, called axons, that relay electrical and chemical signals from one cell to the next.

Vien and other researchers in Professor Pelin Volkan’s lab at Duke are interested in how that wiring gets established during the fly’s development.

By analyzing a subset of neurons responsible for the fly’s sense of smell, the researchers have identified a protein that helps ensure that new neurons extend their axons to the correct spots in the olfactory area of the young fly’s brain and not elsewhere.

Because the same protein is found across the animal kingdom, including humans, the researchers say the work could ultimately shed light on what goes awry within the brains of people living with schizophrenia and other mental illnesses.

Their findings are published in the journal iScience.

Khanh Vien earned her PhD in developmental and stem cell biology in Professor Pelin Volkan’s lab at Duke.
Robin Smith
By Robin Smith

To get a fuller picture of a forest, sometimes research requires a team effort

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Film by Riccardo Morrelas, Zahava Production

For some people, the word “rainforest” conjures up vague notions of teeming jungles. But Camille DeSisto sees something more specific: a complex interdependent web.

For the past few years, the Duke graduate student has been part of a community-driven study exploring the relationships between people, plants and lemurs in a rainforest in northern Madagascar, where the health of one species depends on the health of others.

Many lemurs, for example, eat the fruits of forest trees and deposit their seeds far and wide in their droppings, thus helping the plants spread. People, in turn, depend on the plants for things like food, shelter and medicines.

But increasingly, deforestation and other disturbances are throwing these interactions out of whack.

DeSisto and her colleagues have been working in a 750,000-acre forest corridor in northeast Madagascar known as the COMATSA that connects two national parks.

The area supports over 200 tree species and nine species of lemurs, and is home to numerous communities of people.

A red-bellied lemur (Eulemur rubriventer) in a rainforest in northeast Madagascar. Photo by Martin Braun.

“People live together with nature in this landscape,” said DeSisto, who is working toward her Ph.D. in ecology at the Nicholas School of the Environment.

But logging, hunting and other stressors such as poverty and food insecurity have taken their toll.

Over the last quarter century, the area has lost 14% of its forests, mostly to make way for vanilla and rice.

This loss of wild habitats risks setting off a series of changes. Fewer trees also means fewer fruit-eating lemurs, which could create a feedback loop in which the trees that remain have fewer opportunities to replace themselves and sprout up elsewhere — a critical ability if trees are going to track climate change.

DeSisto and her colleagues are trying to better understand this web of connections as part of a larger effort to maximize forest resilience into an uncertain future.

To do this work, she relies on a network of a different sort.

The research requires dozens of students and researchers from universities in Madagascar and the U.S., not to mention local botanists and lemur experts, the local forest management association, and consultants and guides from nearby national parks, all working together across time zones, cultures and languages.

Forest field team members at camp (not everyone present). Photo credit: Jane Slentz-Kesler.

Together, they’ve found that scientific approaches such as fecal sampling or transect surveys can only identify so much of nature’s interconnected web.

Many lemurs are small, and only active at night or during certain times of year, which can make them hard to spot — especially for researchers who may only be on the ground for a limited time.

To fill the gaps, they’re also conducting interviews with local community members who have accumulated knowledge from a lifetime of living on the land, such as which lemurs like to munch on certain plants, what parts they prefer, and whether people rely on them for food or other uses.

By integrating different kinds of skills and expertise, the team has been able to map hidden connections between species that more traditional scientific methods miss.

For example, learning from the expertise of local community members helped them understand that forest patches that are regenerating after clear-cutting attract nocturnal lemurs that may — depending on which fruits they like to eat — promote the forest’s regrowth.

Camille DeSisto after a successful morning collecting lemur fecal samples.

Research collaborations aren’t unusual in science. But DeSisto says that building collaborations with colleagues more than 9,000 miles away from where she lives poses unique challenges.

Just getting to her field site involves four flights, several bumpy car rides, climbing steep trails and crossing slippery logs.

“Language barriers are definitely a challenge too,” DeSisto said.

She’s been studying Malagasy for seven years, but the language’s 18 dialects can make it hard to follow every joke her colleagues tell around the campfire.

To keep her language skills sharp she goes to weekly tutoring sessions when she’s back in the U.S., and she even helped start the first formal class on the language for Duke students.

“I like to think of it as language opportunities, not just language barriers,” DeSisto said.”

“Certain topics I can talk about with much more ease than others,” she added. “But I think making efforts to learn the language is really important.”

When they can’t have face-to-face meetings the team checks in remotely, using videoconferencing and instant messaging to agree on each step of the research pipeline, from coming up with goals and questions and collecting data to publishing their findings.

“That’s hard to navigate when we’re so far away,” DeSisto said. But, she adds, the teamwork and knowledge sharing make it worth it. “It’s the best part of research.”

This research was supported by Duke Bass Connections (“Biocultural Sustainability in Madagascar,” co-led by James Herrera), Duke Global, The Explorers Club, Primate Conservation, Inc., Phipps Conservatory and Botanical Gardens, and the Garden Club of America.

A Grueling Math Test So Hard, Almost No One Gets a Perfect Score

Yet hundreds of schools compete each year, and this time the Blue Devils made it into the top three

Duke places 3 out of 471 in North America’s most prestigious math competition. The top-scoring 2023 Putnam team consisted of (from L to R): Erick Jiang ’26, Kai Wang ’27, and Fletch Rydell ’26.
Duke placed third out of 471 schools in North America’s most prestigious math competition, the Putnam. The top-scoring team consisted of (L to R): Erick Jiang ’26, Kai Wang ’27, and Fletch Rydell ’26.

Every year, thousands of college students from across the U.S. and Canada give up a full Saturday before finals begin to take a notoriously difficult, 6-hour math test — and not for a grade, but for fun.

In “the Putnam,” as it’s known, contestants spend two 3-hour sessions trying to solve 12 proof-based math problems worth 10 points apiece.

More than 150,000 people have taken the exam in the contest’s 85-year history, but only five times has someone earned a perfect score. Total scores of 1 or 0 are not uncommon.

Despite the odds, the Blue Devils had a strong showing this year.

A total of 3,857 students from 471 schools competed in the December contest. In results announced Feb. 16, a Duke team consisting of Erick Jiang ’26, James “Fletch” Rydell ’26 and Kaixin “Kai” Wang ’27 ranked third in North America behind MIT and Harvard, winning a $15,000 prize for Duke and each taking home $600 for themselves.

According to mathematics professor Lenny Ng, it’s Duke’s best performance in almost 20 years.

“This is the first time a Duke team has placed this high since 2005,” said Ng, who was a three-time Putnam Fellow himself, finishing in the top five each year he was an undergraduate at Harvard.

Duke students sit for an all-day math marathon.

There’s no official syllabus for prepping for the Putnam. To get ready, the students practice working through problems and discussing their solutions in a weekly problem-solving seminar held each fall.

Students serve as the instructors, focusing on a different topic each week ranging from calculus to number theory.

“They get a sense of what the problems are like, so it’s not quite as intimidating as it might be if they went into the contest cold,” said math department chair Robert Bryant.

“Not only do they learn how to do the problems, but they also get to know each other,” said professor emeritus David Kraines, who has coached Duke Putnam participants for more than 30 years.

Kraines said 8-10 students take his problem-solving seminar for credit each fall. “We always get another 10 or so who come for the pizza,” Kraines said.

The biggest difference between a Putnam problem and a homework problem, said engineering student Rydell, is that usually with a homework problem you’ve already been shown what to do; you just have to apply it.

Whereas most of the time in math competitions like the Putnam, “there’s no clear path forward when you first see the problem,” Rydell said. “They’re more about finding some insight or way of looking at the problem in a different perspective.”

Putnam problems are meant to be solvable using only paper and pencil — no computing power required. The contestants work through each problem by hand, trying different paths towards a solution and spelling out their reasoning step-by-step.

This year, one problem involved determining how many configurations of coins are possible given a grid with coins sitting in some of the squares, if those coins are only allowed to move in certain ways.

Another question required knowing something about the geometry of a 20-sided shape known as a icosahedron.

“That was the one I struggled with the most,” said Wang, whose individual score nevertheless tied him for sixth place overall out of 3,857 contestants.

A sample of problems from the 84th Putnam Competition.

The most common question he gets asked about the Putnam, Rydell said, is not so much what’s on the test, but why people take it in the first place.

This year’s test was so challenging that a score of 78 out of 120 or better — just 65% — was enough to earn a spot in the top 10.

Most of the people who took it scored less than 10%, which means many problems went unsolved.

“For days after I took the Putnam, I would think about the problems and wonder: could I have done it better this way? You can become obsessed,” said Bryant, who took the Putnam in the 1970s as a college student at NC State.

Sophomores Jiang and Rydell, who both ranked in the top 5%, see it as an opportunity to “meet people who also enjoy problem solving,” Jiang said.

“I’m not a math major so I probably wouldn’t do much of this kind of problem solving otherwise,” Rydell said.

For Rydell it’s also the aha moment: “Just the reward of when you solve a problem, the feeling of making that breakthrough,” Rydell said.

Professor Kraines’ weekly problem-solving seminar, MATH 283S, takes place on Tuesday evenings at 6:15 p.m. during the fall semester. Registration for Fall 2024 begins April 3.

Robin Smith
By Robin Smith, Marketing & Communications

Putting Stronger Guardrails Around AI

AI regulation is ramping up worldwide. Duke AI law and policy expert Lee Tiedrich discusses where we’ve been and where we’re going.
AI regulation is ramping up worldwide. Duke AI law and policy expert Lee Tiedrich discusses where we’ve been and where we’re going.

DURHAM, N.C. — It’s been a busy season for AI policy.

The rise of ChatGPT unleashed a frenzy of headlines around the promise and perils of artificial intelligence, and raised concerns about how AI could impact society without more rules in place.

Consequently, government intervention entered a new phase in recent weeks as well. On Oct. 30, the White House issued a sweeping executive order regulating artificial intelligence.

The order aims to establish new standards for AI safety and security, protect privacy and equity, stand up for workers and consumers, and promote innovation and competition. It’s the U.S. government’s strongest move yet to contain the risks of AI while maximizing the benefits.

“It’s a very bold, ambitious executive order,” said Duke executive-in-residence Lee Tiedrich, J.D., who is an expert in AI law and policy.

Tiedrich has been meeting with students to unpack these and other developments.

“The technology has advanced so much faster than the law,” Tiedrich told a packed room in Gross Hall at a Nov. 15 event hosted by Duke Science & Society.

“I don’t think it’s quite caught up, but in the last few weeks we’ve taken some major leaps and bounds forward.”

Countries around the world have been racing to establish their own guidelines, she explained.

The same day as the US-led AI pledge, leaders from the Group of Seven (G7) — which includes Canada, France, Germany, Italy, Japan, the United Kingdom and the United States — announced that they had reached agreement on a set of guiding principles on AI and a voluntary code of conduct for companies.

Both actions came just days before the first ever global summit on the risks associated with AI, held at Bletchley Park in the U.K., during which 28 countries including the U.S. and China pledged to cooperate on AI safety.

“It wasn’t a coincidence that all this happened at the same time,” Tiedrich said. “I’ve been practicing law in this area for over 30 years, and I have never seen things come out so fast and furiously.”

The stakes for people’s lives are high. AI algorithms do more than just determine what ads and movie recommendations we see. They help diagnose cancer, approve home loans, and recommend jail sentences. They filter job candidates and help determine who gets organ transplants.

Which is partly why we’re now seeing a shift in the U.S. from what has been a more hands-off approach to “Big Tech,” Tiedrich said.

Tiedrich presented Nov. 15 at an event hosted by Duke Science & Society.

In the 1990s when the internet went public, and again when social media started in the early 2000s, “many governments — the U.S. included — took a light touch to regulation,” Tiedrich said.

But this moment is different, she added.

“Now, governments around the world are looking at the potential risks with AI and saying, ‘We don’t want to do that again. We are going to have a seat at the table in developing the standards.’”

Power of the Purse

Biden’s AI executive order differs from laws enacted by Congress, Tiedrich acknowledged in a Nov. 3 meeting with students in Pratt’s Master of Engineering in AI program.

Congress continues to consider various AI legislative proposals, such as the recently introduced bipartisan Artificial Intelligence Research, Innovation and Accountability Act, “which creates a little more hope for Congress,” Tiedrich said.

What gives the administration’s executive order more force is that “the government is one of the big purchasers of technology,” Tiedrich said.

“They exercise the power of the purse, because any company that is contracting with the government is going to have to comply with those standards.”

“It will have a trickle-down effect throughout the supply chain,” Tiedrich said.

The other thing to keep in mind is “technology doesn’t stop at borders,” she added.

“Most tech companies aren’t limiting their market to one or two particular jurisdictions.”

“So even if the U.S. were to have a complete change of heart in 2024” and the next administration were to reverse the order, “a lot of this is getting traction internationally,” she said.

“If you’re a U.S. company, but you are providing services to people who live in Europe, you’re still subject to those laws and regulations.”

From Principles to Practice

Tiedrich said a lot of what’s happening today in terms of AI regulation can be traced back to a set of guidelines issued in 2019 by the Organization for Economic Cooperation and Development, where she serves as an AI expert.

These include commitments to transparency, inclusive growth, fairness, explainability and accountability.

For example, “we don’t want AI discriminating against people,” Tiedrich said. “And if somebody’s dealing with a bot, they ought to know that. Or if AI is involved in making a decision that adversely affects somebody, say if I’m denied a loan, I need to understand why and have an opportunity to appeal.”

“The OECD AI principles really are the North Star for many countries in terms of how they develop law,” Tiedrich said.

“The next step is figuring out how to get from principles to practice.”

“The executive order was a big step forward in terms of U.S. policy,” Tiedrich said. “But it’s really just the beginning. There’s a lot of work to be done.”

Robin Smith
By Robin Smith

New Blogger Noor Nazir: Mental Health With a Pakistani Twist

My name is Door but replace the ‘D’ with an ‘N’.

Yes, I’m Noor and yes again, that is exactly how I introduced my freshman self to everyone in my year. Before you wonder, it’s an Arabic name and no I’m not from the Middle East! I’m a die-hard Pakistani with an overwhelming – and embarrassing – amount of love for Taylor Swift and Local Pakistani Music (stream Talha Anjum, you’ll be surprised!).

My personality mainly encompasses my thirteen-month-old niece, Alaya. I like to think she’s my mini doppelganger (she is not) and the last eight months of my life have been encapsulated by her cute presence, smelly diapers and charming smile. We spend most of our time listening to Taylor Swift, and – sometimes – the nursery rhyme, One Little Finger.  Other times, we play the guitar and sing for fun (your average Duke freshman).

Although, contrary to the ‘average Duke freshman’ who is sure about the trajectory of their next twenty years, I am not – at all. I find my mind wandering to several distinct fields of interest; whenever a classmate asks me “but where is your mind really at?”, my deliberate and circumspect answer is always “four to be exact: economics, political science, psychology and public policy”’. This answer is invariably met by an overt facial expression screaming their internal thought “oh so she’s really not sure”. But that side eye is beside the point since that uncertainty is precisely what led me to the Duke Research Blog.

In high school, whether it was the debate club or my interest in mental health, I always found a research angle to it. For debate, I’d research different case studies in order to formulate argumentation and rebuttals; for mental health, I’d utilize such case studies and would recreate what worked. My proudest creation, the Safe Space Society (a society in my alma matter, International School Lahore), was nothing short of a camaraderie and a community fostered with love and empathy. In my eyes, such a creation was only made possible because of extensive and life-long research by dedicated professionals.

Not only is research the perfect way to navigate my interests in a fulfilling manner, but it also acts as the tunnel vision to a transfigured world. Since my navigation wishes to find its destination in a declared major, I’m incredibly excited to write and learn about research revolving science, mental health, and anything Duke brings my way.

I am, however, most excited to translate and decode complex and seemingly mundane ideas in a nuanced and amusing way. The blog seems to be on a mission to make potential engineers excited about the next big thing in mental health research; this is a mission I’m excited and honored to take part in.  To sum it up, my goal at Duke Research Blog is to attend the research events you don’t want to and then write about them to make you regret not attending those events!

– A serious warning: you will see me bringing a Pakistani twist to every article I write! It’s just what us Pakistanis do (for a sample look at the sentence above). –

Noor Nazir, Class of 2027
Noor Nazir, Class of 2027

Helping People and Wildlife Coexist in Ways That Benefit Both, Using Math

Duke team wins top prize in mathematical modeling contest


Safari-goers watch a pride of lions in the Maasai Mara, a famous game reserve in Kenya. Credit: Ray in Manila, CC BY 2.0 via Wikimedia Commons
Safari-goers watch a pride of lions in the Maasai Mara, a famous game reserve in Kenya. Credit: Ray in Manila, CC BY 2.0 via Wikimedia Commons

Of all the math competitions for college students, the annual Mathematical Contest in Modeling (MCM) is one of the biggest. And this year, Duke’s team took home a coveted top prize.

Undergraduates Erik Novak, ’24, Nicolas Salazar, ’23, and Enzo Moraes Mescall, ’24, represented the Blue Devils at this year’s contest, a grueling 4-day event where teams of undergraduates use their mathematical modeling skills to solve a real-world problem. The results are finally in, and the Duke team was chosen as one of the top 22 outstanding winners out of more than 11,200 teams worldwide.

Their task: to analyze some of the challenges facing a nature reserve in Kenya known as the Maasai Mara. This region is named for the local Maasai people, a tribe of semi-nomadic people who make a living by herding cattle. It’s also teeming with wildlife. Each year, more than a million wildebeests, zebras and gazelles travel in a loop from neighboring Tanzania into Kenya’s Maasai Mara Reserve and back, following the seasonal rains in search of fresh grass to eat.

Some 300,000 safari-goers also flock to the area to witness the massive migration, making it a major player in Kenya’s billion-dollar tourism industry. But protecting and managing the land for the benefit of both wildlife and people is a delicate balancing act.

The reserve relies on tourism revenue to protect the animals that live there. If tourism slumps — due to political unrest in Kenya, or the COVID-19 pandemic — desperate communities living around the park resort to poaching to get by, threatening the very wildlife that tourism depends on.

Poachers aren’t the only problem: wild animals such as lions, leopards and elephants sometimes venture into human settlements in search of food. Conservationists must strike a balance between protecting these animals and managing the dangers they pose by raiding crops or killing valuable domestic livestock.

Tourism is a mixed blessing, too. While safari-goers bring money into the region, they can also disturb the animals and pollute the Mara River, and off-road drivers can erode the soil with their jeeps.

The mission facing the Duke team was to identify ways to mitigate such conflicts between wildlife and people.

From left: Teammates Erik Novak, ’24, Nicolas Salazar, ’23, and Enzo Moraes Mescall ’24 finished in the top 0.1% in the 2023 Mathematical Contest in Modeling.

This year’s contest ran over a single weekend in February. Camped out on the third floor of Perkins library, the team of three worked 12 hours a day, fueled by a steady supply of Red Bull and poke bowls. During that time, they built a model, came up with budget and policy recommendations, and wrote a 25-page report for the Kenyan Tourism and Wildlife Committee, all in less than 96 hours.

They built a mathematical model consisting of a system of six ordinary differential equations. According to the model’s predictions, they said, it should theoretically be possible to increase the reserve’s animal populations by about 25%, reduce environmental degradation by 20%, nearly eliminate retaliatory lion killings, and cut poaching rates in half — all while increasing the average yearly flow of tourists by 7.5%.

Participating in a smaller-but-similar contest last fall, the Triangle Competition in Mathematical Modeling, helped them prepare. “It’s kind of like a practice for the MCM,” Salazar said.

Veronica Ciocanel

“They did not win that contest, but they took everything they learned and look what they did with it. I’m very proud,” said assistant professor of mathematics and biology Veronica Ciocanel, who coached the team and co-organized the Triangle competition.

In addition to finishing in the top 0.1% of competitors, the Duke team got three additional awards for their performance; the Mathematical Association of America (MAA) award, the Society for Industrial and Applied Mathematics (SIAM) prize, and an International COMAP Scholarship Award of $10,000.

The problems in these contests tend to be much more open-ended than typical coursework. “We didn’t know what the solution was supposed to be or what tools to use,” Novak said.

Modeling, computation and coding skills are certainly important, Ciocanel said. “But really what matters more is practice, teamwork, and communicating their results in a written report. Students who have a solid course background don’t need to do anything else to prepare, they just need to be creative about using what they know from the courses they already took.”

“Use what you have and work well together,” Ciocanel said. “That I think is the most important thing.”

Robin Smith
By Robin Smith

Rewilding the Gut

Processed foods and overuse of antibiotics can wreak havoc on the trillions of bacteria and other microbes that inhabit the gut. A new study of the gut microbiomes of lemurs looks at whether reconnecting with nature can help restore this internal ecosystem to a more natural state. Credit: Sally Bornbusch.

Modern life messes with the microbiome -– the trillions of bacteria and other microbes that live inside the body. Could reconnecting with nature bring this internal ecosystem back into balance?

A new study suggests it can, at least in lemurs. Led by Duke Ph.D. alumnus Sally Bornbusch and her graduate advisor Christine Drea, the research team collected fecal samples from more than 170 ring-tailed lemurs living in various conditions in Madagascar: some were living in the wild, some were kept as pets, and some were rescued from the pet and tourism industries and then relocated to a rescue center in southwestern Madagascar where they ate a more natural diet and had less exposure to people.

Collecting fecal samples in Madagascar

Then the researchers sequenced DNA from the fecal samples to identify their microbial makeup. They found that the longer lemurs lived at the rescue center, the more similar their gut microbes were to those of their wild counterparts. Former pet lemurs with more time at the rescue center also showed fewer signs of antibiotic resistance.

By “rewilding” the guts of captive animals, researchers say we may be able to better prime them for success, whether after rescue or before translocation or reintroduction into the wild.

This research was supported by grants from the National Science Foundation (1945776, 1749465), the Triangle Center for Evolutionary Medicine, Duke’s Kenan Institute for Ethics, the Margot Marsh Biodiversity Fund and Lemur Love.

CITATION: “Microbial Rewilding in the Gut Microbiomes of Captive Ring-Tailed Lemurs (Lemur catta) in Madagascar,” Sally L. Bornbusch, Tara A. Clarke, Sylvia Hobilalaina, Honore Soatata Reseva, Marni LaFleur & Christine M. Drea. Scientific Reports, Dec. 27, 2022. DOI: 10.1038/s41598-022-26861-0.

Robin Smith
By Robin Smith

Modeling the COVID-19 Roller Coaster

A Duke team looks at the math behind COVID’s waves as new coronavirus variants continue to emerge. Credit: @ink-drop

DURHAM, N.C. — First it was Alpha. Then Delta. Now Omicron and its alphabet soup of subvariants. In the three years since the coronavirus pandemic started, every few months or so a new strain seems to go around, only to be outdone by the next one.

If the constant rise and fall of new coronavirus variants has left you feeling dizzy, you’re not alone. But where most people see a pandemic roller coaster, one Duke team sees a mathematical pattern.

In a new study, a group of students led by Duke mathematician Rick Durrett studied the calculus behind the pandemic’s waves.

Published Nov. 2022 in the journal Proceedings of the National Academy of Sciences, their study got its start as part of an 8-week summer research program called DOmath, now known as Math+, which brings undergraduates together to collaborate on a faculty-led project.

Their mission: to build and analyze simple mathematical models to understand the spread of COVID-19 as one strain after another popped up and then rose to outcompete the others.

In an interview about their research, project manager and Duke Ph.D. student Hwai-Ray Tung pointed to a squiggly line showing the number of confirmed COVID cases per capita in the U.S. between January 2020 and October 2022.

The COVID-19 pandemic has unfolded in waves. Adapted from The New York Times, July 18, 2022

“You can see very distinct humps,” Tung said.

The COVID pandemic has unfolded in a series of surges and lulls — spikes in infection followed by downturns in case counts.

The ups and downs are partly explained by factors such as behavior, relaxation of public policies, and waning immunity from vaccines. But much of the roller coaster has been driven by changes to the coronavirus itself.

All viruses change over time, evolving mutations in their genetic makeup as they spread and replicate. Most mutations are harmless, but every so often some of them give the virus an edge: Enabling it to break into cells more easily than other strains, better evade immunity from vaccines and past infection, or make more copies of itself in order to spread more effectively.

Take the Delta variant, for example. When it first started going around in the U.S. in May 2021, it was responsible for just 1% of COVID cases. But thanks to mutations that helped the virus evade antibodies and infect cells more easily, it quickly tore across the country. Within two months it had outcompeted all the other variants and rose to the top spot, causing 94% of new infections.

“The natural question to ask is: What’s going on with the transition between these different variants?” Tung said.

For their study the team developed a simple epidemic model called an SIR model, which uses differential equations to compute the spread of disease over time.

SIR models work by categorizing individuals as either susceptible to getting sick, currently infected, or recovered. The team modified this model to have two types of infected individuals and two types of recovered individuals, one for each of two circulating strains.

The model assumes that each infectious person spreads the virus to a certain number of new people per day (while sparing others), and that, each day, a certain fraction of the currently infected group recovers.

In the study, the team applied the SIR model to data from a database called GISAID, which contains SARS-CoV-2 virus sequences from the pandemic. By looking at the coronavirus’s genetic code, researchers can tell which variants are causing infection.

Study co-author Jenny Huang ’23 pointed to a series of S-shaped curves showing the fraction of infections due to each strain from one week to the next, from January 2021 to June 2022.

When they plotted the data as points on a graph, they found that it followed a logistic differential equation as each new variant emerged, rose steeply, and — within six to 10 weeks — quickly displaced its predecessors, only to be taken over later by even more aggressive or contagious strains.

Durrett said it’s the mathematical equivalent of something biologists call a selective sweep, when natural selection increases a variant’s frequency from low to high, until nearly everyone getting stick is infected with the same strain.

“I’ve been interested in epidemic modeling since the end of freshman year when COVID started,” said Huang, a senior who plans to pursue a Ph.D. in statistics next year with support from a prestigious Quad Fellowship.

They’re not all typical math majors, Durrett said of his team. Co-author Sofia Hletko, ’25, was a walk-on to the rowing team. Laura Boyle ’24 was a Cameron Crazie.

For some team members it was their first experience with mathematical research: “I came in having no idea what a differential equation was,” Boyle said. “And by the end, I was the person in the group explaining that part of our presentation to everyone.”

Boyle says one question she keeps getting asked is: what about the next COVID surge?

“It’s very hard to say what will happen,” Boyle said.

The teams says their research can’t predict future waves. Part of the reason is the scanty data on the actual number of infections.

Countries have dialed back on their surveillance testing, and fewer places are doing the genomic sequencing necessary to identify different strains.

“We don’t know the nature of future mutations,” Durrett said. “Changes in people’s behavior will have a significant impact too.”

“The point of this paper wasn’t to predict; rather it was to explain why the waves were occurring,” Huang said. “We were trying to explain a complicated phenomenon in a simple way.”

This research was supported by a grant from the National Science Foundation (DMS 1809967) and by Duke’s Department of Mathematics.

CITATION: “Selective Sweeps in SARS-CoV-2 Variant Competition,” Laura Boyle, Sofia Hletko, Jenny Huang, June Lee, Gaurav Pallod, Hwai-Ray Tung, and Richard Durrett. Proceedings of the National Academy of Sciences, Nov. 3, 2022. DOI: 10.1073/pnas.2213879119.

Robin Smith
By Robin Smith

For Weary Scholars, a Moment to Regroup, Reconnect…and Write

DURHAM, N.C. — English professor Charlotte Sussman doesn’t get much time in her role as department chair to work on her latest book project, an edited collection of essays on migration in and out of Europe.

“At least not during daylight hours,” Sussman said.

But a recent workshop brought a welcome change to that. Sussman was one of 22 faculty who gathered Dec. 13 for an end-of-semester writing retreat hosted by the Duke Faculty Write Program.

Duke faculty and staff gather for an end-of-semester writing retreat.

Most of them know all too well the burnout faculty and students face at the end of the semester. But for a few precious hours, they hit pause on the constant onslaught of emails, meetings, grading and other duties to work alongside fellow writers.

The participants sat elbow-to-elbow around small tables in a sunlit room at the Duke Integrative Medicine Center. Some scribbled on pads of paper; others peered over their laptops.

Each person used the time to focus on a specific writing project. Sussman aimed to tackle an introduction for her 34-essay collection. Others spent the day working on a grant application, a book chapter, a course proposal, a conference presentation.

Jennifer Ahern-Dodson, Ph.D.
Jennifer Ahern-Dodson, Ph.D.

“We have so many negative associations with writing because there’s always something more to do,” said associate professor of the practice Jennifer Ahern-Dodson, who directs the program. “I want to change the way people experience writing.”

Ahern-Dodson encouraged the group to break their projects into small, specific tasks as they worked toward their goals. It might be reading a journal article, drafting an outline, organizing some notes, even just creating or finding a file.

After a brief workshop, she kicked off a 60-minute writing session. “Now we write!” she said.

The retreat is the latest installment in a series that Ahern-Dodson has been leading for over 10 years. In a typical week, most of these scholars wouldn’t find themselves in the same room. There were faculty and administrators from fields as diverse as history, African and African American Studies, law, psychology, classics, biostatistics. New hires sitting alongside senior scholars with decades at Duke.

Peggy Nicholson, J.D., Clinical Professor of Law, writing alongside colleagues from across campus

“I really like the diversity of the group,” said Carolyn Lee, Professor of the Practice of Asian and Middle Eastern Studies. “It’s a supportive environment without any judgement. They all have the same goal: they want to get some writing done.”

Sussman said such Faculty Write program get-togethers have been “indispensable” to bringing some of her writing projects over the finish line.

Participants say the program not only fosters productivity, but also a sense of connection and belonging. Take Cecilia Márquez, assistant professor in the Duke History Department. She joined the Duke faculty in 2019, but within months the world went into COVID-19 lockdown.

“This was my way to meet colleagues,” said Márquez, who has since started a writing group for Latinx scholars as an offshoot.

The writing retreats are free for participants, thanks to funding from the Office of the Dean of Trinity College of Arts and Sciences and the Thompson Writing Program. Participants enjoy lunch, coaching and community in what’s normally a solitary activity.

“I appreciate the culture of collaboration,” said David Landes, who came to Duke this year as Assistant Professor of the Practice in Duke’s Thompson Writing Program. “In the humanities our work is intensely individualized.”

Assistant Professor of Biostatistics & Bioinformatics Hwanhee Hong (left) and Adam Rosenblatt, Associate Professor of the Practice in International Comparative Studies (right)

Retreats are one of many forms of support offered by the Faculty Write program: there are also writing groups and workshops on topics such as balancing teaching and scholarship or managing large research projects.

“One of the distinguishing features of Faculty Write is the community that extends beyond one event,” Ahern-Dodson said. “Many retreats are reunions.”

After two hours of writing, Ahern-Dodson prompted the group to take a break. Some got up to stretch or grab a snack; others stepped outside to chat or stroll through the center’s labyrinth at the edge of Duke Forest.

It’s more than just dedicated writing time, Ahern-Dodson said. It’s also “learning how to work with the time they have.”

The retreats offer tips from behavioral psychology, writing studies, and other disciplines on time management, motivation, working with reader feedback, and other topics.

As they wrap up the last writing session of the day, Ahern-Dodson talks about how to keep momentum.

“Slow-downs and writing block are normal,” Ahern-Dodson said. Maybe how you wrote before isn’t working anymore, or you’re in a rut. Perhaps you’re not sure how to move forward, or maybe writing simply feels like a slog.

“There are some things you could try to get unstuck,” Ahern-Dodson said. Consider changing up your routine: when and where you write, or how long each writing session lasts.

“Protect your writing time as you would any other meeting,” Ahern-Dodson said.

Sharing weekly goals and accomplishments with other people can help too, she added.

“Celebrate each win.”

Ultimately, Ahern-Dodson says, the focus is not on productivity but on meaning, progress and satisfaction over time.

“It’s all about building a sustainable writing practice,” she said.

Ahern-Dodson leads an end-of-semester writing retreat for Duke scholars.

Coming soon: On Friday, Jan. 27 from 12-1 p.m., join Vice Provost for Faculty Advancement Abbas Benmamoun for a conversation about how writing works for him as a scholar and administrator. In person in Rubenstein Library 249 (Carpenter Fletcher Room)

Get Involved: Faculty and staff are invited to sign up for writing groups for spring 2023 here.

Learn more about sustainable writing practices: “The Productivity Trap: Why We Need a New Model of Faculty Writing Support,” Jennifer Ahern-Dodson and Monique Dufour. Change, January/February 2023.

Robin Smith
By Robin Smith

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