Duke Research Blog

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

Category: Students (Page 1 of 35)

A Summer Well-Spent In and Around Toxic Waste Sites

Edison, NJ is just 40 miles from Manhattan and 70 miles from Philadelphia. It’s also home to the US EPA’s Emergency Response Team (ERT), where I spent the summer as an intern.

Stella Wang and an EPA contractor used lifts to test oil being pumped out of these huge tanks. It was found to be contaminated with mercury, benzene and lead.

At the start of my internship, I had little idea of how ERT functioned. Unlike the 10 regional offices of the Environmental Protection Agency, ERT is a “headquarters” or Washington, DC-based group, which means it responds to incidents all over the country such as oil spills, train derailments, and natural disasters.

For example, my mentor, an air specialist who generally works from his cubicle in Edison, aided in the immediate aftermath of Hurricane Katrina by employing equipment to analyze air for hazardous pollutants. Other ERT team members have conducted sediment sampling to expedite the hazardous waste removal process, given consultation advice to other EPA members for long-term remedial site work, and led the innovation of new technology.

I was able to shadow and help my mentor and fellow ERT members with their Superfund site removal work. I created accurate maps showing injection well locations, learned how to use air monitoring instruments, and helped perform chemical lab experiments that will be employed for future site analysis.

Perhaps my favorite part of the internship was traveling to a myriad of active sites. At these sites, I not only got to see how ERT members worked with EPA’s on-scene coordinators, but also observed the physical removal and remediation processes. I was fortunate to visit a particular site multiple times — I witnessed the removal of contaminated oil from an abandoned lot as the summer progressed.

Stella Wang (left) and an EPA air specialist calibrating a air monitoring instrument before a public event.

At another site, I saw the beginning of an injection process intended to prevent the contamination of underground drinking water by hexavalent chromium. By pumping sodium lactate into underground wells, the hexavalent is converted into the insoluble and benign chromium-3 ion. If the injection process works, the community will no longer be threatened by this particular hazardous material.

ERT also acts in anticipation of possible contamination to protect the public. At largely attended events like the Democratic National Convention, a few ERT members will arrive with monitoring equipment. They pride themselves in their real-time data collection for a reason: throughout the event, they can detect whether a contaminant has been released and immediately instigate an emergency response to protect attendees.

Thanks to various ERT members, I felt accepted and welcome. They were open and patient with my never-ending questions about their career paths and other things. They’ve graciously taken me out to lunch so that they could get to know me better, ensuring my inclusion in their small community.

Of course, the experiences I had this summer, while brief, have taught me a tremendous amount and I have a clearer sense of how this division of the US federal government functions. But, it would be inaccurate and unjust to omit the impact that its people made on me.

Stella Wang, Duke 2019Guest post by Stella Wang, Class of 2019

Pinpointing Where Durham’s Nicotine Addicts Get Their Fix

DURHAM, N.C. — It’s been five years since Durham expanded its smoking ban beyond bars and restaurants to include public parks, bus stops, even sidewalks.

While smoking in the state overall may be down, 19 percent of North Carolinians still light up, particularly the poor and those without a high school or college diploma.

Among North Carolina teens, consumption of electronic cigarettes in particular more than doubled between 2013 and 2015.

Now, new maps created by students in the Data+ summer research program show where nicotine addicts can get their fix.

Studies suggest that tobacco retailers are disproportionately located in low-income neighborhoods.

Living in a neighborhood with easy access to stores that sell tobacco makes it easier to start young and harder to quit.

The end result is that smoking, secondhand smoke exposure, and smoking-related diseases such as lung cancer, are concentrated among the most socially disadvantaged communities.

If you’re poor and lack a high school or college diploma, you’re more likely to live near a store that sells tobacco.

If you’re poor and lack a high school or college diploma, you’re more likely to live near a store that sells tobacco. Photo from Pixabay.

Where stores that sell tobacco are located matters for health, but for many states such data are hard to come by, said Duke statistics major James Wang.

Tobacco products bring in more than a third of in-store sales revenue at U.S. convenience stores — more than food, beverages, candy, snacks or beer. Despite big profits, more than a dozen states don’t require businesses to get a special license or permit to sell tobacco. North Carolina is one of them.

For these states, there is no convenient spreadsheet from the local licensing agency identifying all the businesses that sell tobacco, said Duke undergraduate Nikhil Pulimood. Previous attempts to collect such data in Virginia involved searching for tobacco retail stores by car.

“They had people physically drive across every single road in the state to collect the data. It took three years,” said team member and Duke undergraduate Felicia Chen.

Led by UNC PhD student in epidemiology Mike Dolan Fliss, the Duke team tried to come up with an easier way.

Instead of collecting data on the ground, they wrote an automated web-crawler program to extract the data from the Yellow Pages websites, using a technique called Web scraping.

By telling the software the type of business and location, they were able to create a database that included the names, addresses, phone numbers and other information for 266 potential tobacco retailers in Durham County and more than 15,500 statewide, including chains such as Family Fare, Circle K and others.

Map showing the locations of tobacco retail stores in Durham County, North Carolina.

Map showing the locations of tobacco retail stores in Durham County, North Carolina.

When they compared their web-scraped data with a pre-existing dataset for Durham County, compiled by a nonprofit called Counter Tools, hundreds of previously hidden retailers emerged on the map.

To determine which stores actually sold tobacco, they fed a computer algorithm data from more than 19,000 businesses outside North Carolina so it could learn how to distinguish say, convenience stores from grocery stores. When the algorithm received store names from North Carolina, it predicted tobacco retailers correctly 85 percent of the time.

“For example we could predict that if a store has the word “7-Eleven” in it, it probably sells tobacco,” Chen said.

As a final step, they also crosschecked their results by paying people a small fee to search for the stores online to verify that they exist, and call them to ask if they actually sell tobacco, using a crowdsourcing service called Amazon Mechanical Turk.

Ultimately, the team hopes their methods will help map the more than 336,000 tobacco retailers nationwide.

“With a complete dataset for tobacco retailers around the nation, public health experts will be able to see where tobacco retailers are located relative to parks and schools, and how store density changes from one neighborhood to another,” Wang said.

The team presented their work at the Data+ Final Symposium on July 28 in Gross Hall.

Data+ is sponsored by Bass Connections, the Information Initiative at Duke, the Social Science Research Institute, the departments of mathematics and statistical science and MEDx. This project team was also supported by Counter Tools, a non-profit based in Carrboro, NC.

Writing by Robin Smith; video by Lauren Mueller and Summer Dunsmore

Sizing Up Hollywood’s Gender Gap

DURHAM, N.C. — A mere seven-plus decades after she first appeared in comic books in the early 1940s, Wonder Woman finally has her own movie.

In the two months since it premiered, the film has brought in more than $785 million worldwide, making it the highest grossing movie of the summer.

But if Hollywood has seen a number of recent hits with strong female leads, from “Wonder Woman” and “Atomic Blonde” to “Hidden Figures,” it doesn’t signal a change in how women are depicted on screen — at least not yet.

Those are the conclusions of three students who spent ten weeks this summer compiling and analyzing data on women’s roles in American film, through the Data+ summer research program.

The team relied on a measure called the Bechdel test, first depicted by the cartoonist Alison Bechdel in 1985.

Bechdel test

The “Bechdel test” asks whether a movie features at least two women who talk to each other about anything besides a man. Surprisingly, a lot of films fail. Art by Srravya [CC0], via Wikimedia Commons.

To pass the Bechdel test, a movie must satisfy three basic requirements: it must have at least two named women in it, they must talk to each other, and their conversation must be about something other than a man.

It’s a low bar. The female characters don’t have to have power, or purpose, or buck gender stereotypes.

Even a movie in which two women only speak to each other briefly in one scene, about nail polish — as was the case with “American Hustle” —  gets a passing grade.

And yet more than 40 percent of all U.S. films fail.

The team used data from the bechdeltest.com website, a user-compiled database of over 7,000 movies where volunteers rate films based on the Bechdel criteria. The number of criteria a film passes adds up to its Bechdel score.

“Spider Man,” “The Jungle Book,” “Star Trek Beyond” and “The Hobbit” all fail by at least one of the criteria.

Films are more likely to pass today than they were in the 1970s, according to a 2014 study by FiveThirtyEight, the data journalism site created by Nate Silver.

The authors of that study analyzed 1,794 movies released between 1970 and 2013. They found that the number of passing films rose steadily from 1970 to 1995 but then began to stall.

In the past two decades, the proportion of passing films hasn’t budged.

Since the mid-1990s, the proportion of films that pass the Bechdel test has flatlined at about 50 percent.

Since the mid-1990s, the proportion of films that pass the Bechdel test has flatlined at about 50 percent.

The Duke team was also able to obtain data from a 2016 study of the gender breakdown of movie dialogue in roughly 2,000 screenplays.

Men played two out of three top speaking roles in more than 80 percent of films, according to that study.

Using data from the screenplay study, the students plotted the relationship between a movie’s Bechdel score and the number of words spoken by female characters. Perhaps not surprisingly, films with higher Bechdel scores were also more likely to achieve gender parity in terms of speaking roles.

“The Bechdel test doesn’t really tell you if a film is feminist,” but it’s a good indicator of how much women speak, said team member Sammy Garland, a Duke sophomore majoring in statistics and Chinese.

Previous studies suggest that men do twice as much talking in most films — a proportion that has remained largely unchanged since 1995. The reason, researchers say, is not because male characters are more talkative individually, but because there are simply more male roles.

“To close the gap of speaking time, we just need more female characters,” said team member Selen Berkman, a sophomore majoring in math and computer science.

Achieving that, they say, ultimately comes down to who writes the script and chooses the cast.

The team did a network analysis of patterns of collaboration among 10,000 directors, writers and producers. Two people are joined whenever they worked together on the same movie. The 13 most influential and well-connected people in the American film industry were all men, whose films had average Bechdel scores ranging from 1.5 to 2.6 — meaning no top producer is regularly making films that pass the Bechdel test.

“What this tells us is there is no one big influential producer who is moving the needle. We have no champion,” Garland said.

Men and women were equally represented in fewer than 10 percent of production crews.

But assembling a more gender-balanced production team in the early stages of a film can make a difference, research shows. Films with more women in top production roles have female characters who speak more too.

“To better represent women on screen you need more women behind the scenes,” Garland said.

Dollar for dollar, making an effort to close the Hollywood gender gap can mean better returns at the box office too. Films that pass the Bechdel test earn $2.68 for every dollar spent, compared with $2.45 for films that fail — a 23-cent better return on investment, according to FiveThirtyEight.

Other versions of the Bechdel test have been proposed to measure race and gender in film more broadly. The advantage of analyzing the Bechdel data is that thousands of films have already been scored, said English major and Data+ team member Aaron VanSteinberg.

“We tried to watch a movie a week, but we just didn’t have time to watch thousands of movies,” VanSteinberg said.

A new report on diversity in Hollywood from the University of Southern California suggests the same lack of progress is true for other groups as well. In nearly 900 top-grossing films from 2007 to 2016, disabled, Latino and LGBTQ characters were consistently underrepresented relative to their makeup in the U.S. population.

Berkman, Garland and VanSteinberg were among more than 70 students selected for the 2017 Data+ program, which included data-driven projects on photojournalism, art restoration, public policy and more.

They presented their work at the Data+ Final Symposium on July 28 in Gross Hall.

Data+ is sponsored by Bass Connections, the Information Initiative at Duke, the Social Science Research Institute, the departments of mathematics and statistical science and MEDx. 

Writing by Robin Smith; video by Lauren Mueller and Summer Dunsmore

Mapping Electricity Access for a Sixth of the World’s People

DURHAM, N.C. — Most Americans can charge their cell phones, raid the fridge or boot up their laptops at any time without a second thought.

Not so for the 1.2 billion people — roughly 16 percent of the world’s population — with no access to electricity.

Despite improvements over the past two decades, an estimated 780 million people will still be without power by 2030, especially in rural parts of sub-Saharan Africa, Asia and the Pacific.

To get power to these people, first officials need to locate them. But for much of the developing world, reliable, up-to-date data on electricity access is hard to come by.

Researchers say remote sensing can help.

For ten weeks from May through July, a team of Duke students in the Data+ summer research program worked on developing ways to assess electricity access automatically, using satellite imagery.

“Ground surveys take a lot of time, money and manpower,” said Data+ team member Ben Brigman. “As it is now, the only way to figure out if a village has electricity is to send someone out there to check. You can’t call them up or put out an online poll, because they won’t be able to answer.”

India at night

Satellite image of India at night. Large parts of the Indian countryside still aren’t connected to the grid, but remote sensing, machine learning could help pinpoint people living without power. Credits: NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA’s Goddard Space Flight Center

Led by researchers in the Energy Data Analytics Lab and the Sustainable Energy Transitions Initiative, “the initial goal was to create a map of India, showing every village or town that does or does not have access to electricity,” said team member Trishul Nagenalli.

Electricity makes it possible to pump groundwater for crops, refrigerate food and medicines, and study or work after dark. But in parts of rural India, where Nagenalli’s parents grew up, many households use kerosene lamps to light homes at night, and wood or animal dung as cooking fuel.

Fires from overturned kerosene lamps are not uncommon, and indoor air pollution from cooking with solid fuels contributes to low birth weight, pneumonia and other health problems.

In 2005, the Indian government set out to provide electricity to all households within five years. Yet a quarter of India’s population still lives without power.

Ultimately, the goal is to create a machine learning algorithm — basically a set of instructions for a computer to follow — that can recognize power plants, irrigated fields and other indicators of electricity in satellite images, much like the algorithms that recognize your face on Facebook.

Rather than being programmed with specific instructions, machine learning algorithms “learn” from large amounts of data.

This summer the researchers focused on the unsung first step in the process: preparing the training data.

Phoenix power plant

Satellite image of a power plant in Phoenix, Arizona

Fellow Duke students Gouttham Chandrasekar, Shamikh Hossain and Boning Li were also part of the effort. First they compiled publicly available satellite images of U.S. power plants. Rather than painstakingly framing and labeling the plants in each photo themselves, they tapped the powers of the Internet to outsource the task and hired other people to annotate the images for them, using a crowdsourcing service called Amazon Mechanical Turk.

So far, they have collected more than 8,500 image annotations of different kinds of power plants, including oil, natural gas, hydroelectric and solar.

The team also compiled firsthand observations of the electrification rate for more than 36,000 villages in the Indian state of Bihar, which has one of the lowest electrification rates in the country. For each village, they also gathered satellite images showing light intensity at night, along with density of green land and other indicators of irrigated farms, as proxies for electricity consumption.

Using these data sets, the goal is to develop a computer algorithm which, through machine learning, teaches itself to detect similar features in unlabeled images, and distinguishes towns and villages that are connected to the grid from those that aren’t.

“We would like to develop our final algorithm to essentially go into a developing country and analyze whether or not a community there has access to electricity, and if so what kind,” Chandrasekar said.

Electrification map of Bihar, India

The proportion of households connected to the grid in more than 36,000 villages in Bihar, India

The project is far from finished. During the 2017-2018 school year, a Bass Connections team will continue to build on their work.

The summer team presented their research at the Data+ Final Symposium on July 28 in Gross Hall.

Data+ is sponsored by Bass Connections, the Information Initiative at Duke, the Social Science Research Institute, the departments of mathematics and statistical science and MEDx. This project team was also supported by the Duke University Energy Initiative.

Writing by Robin Smith; video by Lauren Mueller and Summer Dunsmore

From Solid to Liquid and Back Again

A black and white moving image of a ball being pulled out from under a pile of circular discs

Force chains erupt as an “intruder” is yanked from beneath a pile of circular discs, which are designed to simulate a granular material. The entire process takes less than one second. Credit: Yue Zhang, Duke University.

You can easily walk across the sand on a beach. But step into a ball pit, and chances are you’ll fall right through.

Sand and ball pits are both granular materials, or materials that are made of collections of much smaller particles or grains. Depending on their density and how much force they experience, granular materials sometimes behave like liquids — something you fall right through — and sometimes “jam” into solids, making them something you can stand on.

“In some cases, these little particles have figured out how to actually form solid-like structures,” said Robert P. Behringer, James B. Duke Professor of Physics. “So why don’t they always just go squirting sideways and relax all the stress?”

Physicists do not yet understand exactly when and how jamming occurs, but Behringer’s team at Duke is on the case. The group squishes, stretches, hits, and pulls at granular materials to get a better picture of how and why they behave like they do. The team recently presented a whopping 10 papers at the 2017 Powders and Grains Conference, which occurred from July 3-7, 2017 in Montpellier, France.

Many of these studies use one of the lab’s favorite techniques, which is to create granular materials from small transparent discs that are about half an inch to an inch in diameter. These discs are made of a material which, thanks to the special way it interacts with light, changes color when squished. This effect allows the team to watch how the stress within the material changes as various forces are applied.

A blue and green moving image of spinning discs

As the wheels turn, shear strain between the discs creates a dense web of inter-particle forces. Credit: Yiqiu Zhao, Duke University.

In one experiment, graduate student Yue Zhang used a high-speed camera to catch the stress patterns as a ball on a string is yanked out from a pile of these discs. In the video, the ball first appears to be stuck under the pile, and then suddenly gives way after enough force is applied — not unlike what you might experience pulling a tent stake out of the ground, or opening the lid on a pesky pickle jar.

“The amusing thing is that you start trying to pull, you add more force, you add more force, and then at some point you pull so hard that you hit yourself in the head,” Behringer said.

The team was surprised to find that the stress patterns created by the ball, which Behringer says look “like hair all standing on end,” are almost identical to the stress of impact, only in reverse.

“What you see is even though you are just gradually gradually pulling harder and harder, the final dynamics are in some sense the same dynamics that you get on impact,” Behringer said.

In another experiment, the team examined what happens in granular materials under shear strain, which is similar to the force your fingers exert on one another when you rub them together.

Graduate student Yiqiu Zhao placed hundreds of these discs onto a circular platform made of a series of flat, concentric rings, each of which is controlled by a separate motor. As the rings turn at different speeds, the particles rub against one another, creating a shear stress.

An image of an experimental set up in a lab

Beneath the small transparent discs lie a series of concentric wheels, each attached to its own motor. By turning these platforms at different speeds, Yiqiu Zhao can observe how shear strain affects the discs.

“We have about twenty stepper motors here, so that we can rotate all the rings to apply a shear not only from the outside boundary, but also from everywhere inside the bulk of the material,” Zhao said. This ensures that each particle in the circle experiences a similar amount of shear.

“One of the key intents of this new experiment was to find a way that we could shear until the cows come home,” Behringer said. “And if it takes a hundred times more shear than I could get with older experiments, well we’ll get it.”

As the rings turn, videos of the material show forces snaking out from the inner circle like lightning bolts. They found that by applying enough shear, it is possible to make the material like a solid at much lower densities than had been seen before.

“You can actually turn a granular fluid into a granular solid by shearing it,” Behringer said. “So it is like you don’t put your ice in the refrigerator, you put it in one of these trays and you shear the tray and it turns into ice.”

Kara J. Manke, PhDPost by Kara Manke

Science on the Trail

Duke launches free two-week girls science camp in Pisgah National Forest.

Duke launches free two-week girls science camp in Pisgah National Forest.

DURHAM, N.C. — To listen to Destoni Carter from Raleigh’s Garner High School, you’d never know she had a phobia of snails. At least until her first backpacking trip, when a friend convinced her to let one glide over her outstretched palm.

Destoni Carter

Destoni Carter from Raleigh’s Garner High School was among eight high schoolers in a new two-week camp that combines science and backpacking.

Soon she started picking them up along the trail. She would collect a couple of snails, put them on a bed of rocks or soil or leaves, and watch to see whether they were speedier on one surface versus another, or at night versus the day.

The experiment was part of a not-so-typical science class.

From June 11-23, 2017, eight high school girls from across North Carolina and four Duke Ph.D. students left hot showers and clean sheets behind, strapped on their boots and packs, and ventured into Pisgah National Forest.

For the high schoolers, it was their first overnight hike. They experienced a lot of things you might expect on such a trip: Hefty packs. Sore muscles. Greasy hair. Crusty socks. But they also did research.

The girls, ages 15-17, were part of a new free summer science program, called Girls on outdoor Adventure for Leadership and Science, or GALS. Over the course of 13 days, they learned ecology, earth science and chemistry while backpacking with Duke scientists.

Duke ecology Ph.D. student Jacqueline Gerson came up with the idea for the program. “Backpacking is a great way to get people out of their comfort zones, and work on leadership development and teambuilding,” said Gerson, who also teamed up with co-instructors Emily Ury, Alice Carter and Emily Levy, all Ph.D. students in ecology or biology at Duke.

Marwa Hassan of Riverside High School in Durham studying stream ecology as part of a two-week summer science program in Pisgah National Forest. Photo by Savannah Midgette.

Marwa Hassan of Riverside High School in Durham studying stream ecology as part of a two-week summer science program in Pisgah National Forest. Photo by Savannah Midgette.

The students hauled 30- to 40-pound loads on their backs for up to five miles a day, through all types of weather. For the first week and a half they covered different themes each day: evolution, geology, soil formation, aquatic chemistry, contaminants. Then on the final leg they chose an independent project. Armed with hand lenses, water chemistry test strips, measuring tapes and other gear, each girl came up with a research question, and had two days to collect and analyze the data.

Briyete Garcia-Diaz of Kings Mountain High School surveyed rhododendrons and other trees at different distances from streambanks to see which species prefer wet soils.

Marwa Hassan of Riverside High School in Durham waded into creeks to net mayfly nymphs and caddisfly larvae to diagnose the health of the watershed.

Savannah Midgette of Manteo High School counted mosses and lichens on the sides of trees, but she also learned something about the secret of slug slime.

“If you lick a slug it makes your tongue go numb. It’s because of the protective coating they have,” Midgette said.

High schoolers head to the backcountry to learn the secret of slug slime and other discoveries of science and self in new girls camp

High schoolers head to the backcountry to learn the secret of slug slime and other discoveries of science and self in new girls camp

The hiking wasn’t always easy. On their second day they were still hours from camp when a thunderstorm rolled in. “We were still sore from the previous day. It started pouring. We were soaking wet and freezing. We did workouts to keep warm,” Midgette said.

At camp they took turns cooking. They stir fried chicken and vegetables and cooked pasta for dinner, and somebody even baked brownies for breakfast. Samantha Cardenas of Charlotte Country Day School discovered that meals that seem so-so at home taste heavenly in the backcountry.

“She would be like, ugh, chicken in a can? And then eat it and say: ‘That’s the most amazing thing I’ve ever had,’” said co-instructor Emily Ury.

Savannah Midgette and Briyete Garcia-Diaz drawing interactions within terrestrial systems as part of a new free summer science program called Girls on outdoor Adventure for Leadership and Science, or GALS. Learn more at https://sites.duke.edu/gals/.

Savannah Midgette and Briyete Garcia-Diaz drawing interactions within terrestrial systems as part of a new free summer science program called Girls on outdoor Adventure for Leadership and Science, or GALS. Learn more at https://sites.duke.edu/gals/.

The students were chosen from a pool of over 90 applicants, said co-instructor Emily Levy. There was no fee to participate in the program. Thanks to donations from Duke Outdoor Adventures, Project WILD and others, the girls were able to borrow all the necessary camping gear, including raincoats, rain pants, backpacks, tents, sleeping bags, sleeping pads and stoves.

The students presented their projects on Friday, June 23 in Environment Hall on Duke’s West Campus. Standing in front of her poster in a crisp summer dress, Destoni Carter said going up and down steep hills was hard on her knees. But she’s proud to have made it to the summit of Shining Rock Mountain to see the stunning vistas from the white quartz outcrop near the top.

“I even have a little bit of calf muscle now,” Carter said.

Funding and support for GALS was provided by Duke’s Nicholas School of the Environment, Duke ecologist Nicolette Cagle, the Duke Graduate School and private donors via GoFundMe.

2017 GALS participants (left to right): Emily Levy of Duke, Destoni Carter of Garner High School, Zyrehia Polk of East Mecklenburg High School, Rose DeConto of Durham School of the Arts, Briyete Garcia-Diaz of Kings Mountain High School, Marwa Hassan of Riverside High School, Jackie Gerson of Duke, Daiana Mendoza of Harnett Central High School, Savannah Midgette of Manteo High School, Samantha Cardenas of Charlotte Country Day School and Alice Carter of Duke.

2017 GALS participants (left to right): Emily Levy of Duke, Destoni Carter of Garner High School, Zyrehia Polk of East Mecklenburg High School, Rose DeConto of Durham School of the Arts, Briyete Garcia-Diaz of Kings Mountain High School, Marwa Hassan of Riverside High School, Jackie Gerson of Duke, Daiana Mendoza of Harnett Central High School, Savannah Midgette of Manteo High School, Samantha Cardenas of Charlotte Country Day School and Alice Carter of Duke.

 

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