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

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Student Team Quantifies Housing Discrimination in Durham

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Home values and race have an intimate connection in Durham, NC. From 1940 to 2020, if mean home values in Black-majority Census tracts had appreciated at rates equal to those in white Census tracts, the mean home value for homes in Black tracts would be $94,642 higher than it is.

That’s the disappointing, but perhaps not shocking, finding of a Duke Data+ team.

Because housing accounts for the biggest portion of wealth for families that fall outside of the top 10% of wealth in the U.S., this figure on home values represents a pervasive racial divide in wealth.

What started as a Data+ project in the summer of 2020 has expanded into an ongoing exploration of the connection between persistent wealth disparities across racial lines through housing. Omer Ali (Ph.D.), a postdoctoral associate with The Samuel Dubois Cook Center on Social Equity, is leading undergraduates Nicholas Datto and Pei Yi Zhuo in the continuation of their initial work. The trio presented an in-depth analysis of their work and methods Friday, February 5th during a Data Dialogue.

The team used a multitude of data to conduct their analyses, including the 1940 Census, Durham County records, CoreLogic data for home sales and NC voter registrations. Aside from the nearly $100,000 difference between mean home values between Black census tracts (defined as >50% Black homeowners from 1940-2020) and white census tracts (defined as >50% white homeowners from 1940-2020), Ali, Datto, and Zhou also found that over the last 10 years, home values have risen in Black neighborhoods as they have been losing Black residents. Within Census tracts, the team said that Black home-buyers in Durham occupy the least valuable homes.

Home Owners Loan Corporation data

Datto introduced the concept of redlining — systemic housing discrimination — and explained how this historic issue persists. From 1930-1940, the Home Owners’ Loan Corporation (HOLC) and Federal Housing Administration (FHA) designated certain neighborhoods unsuitable for mortgage lending. Neighborhoods were given a desirability grade from A to D, with D being the lowest.

In 1940, no neighborhoods with Black residents were designated as either A or B districts. That meant areas with non-white residents were considered more risky and thus less likely to receive FHA-guaranteed mortgages.

Datto explained that these historic classifications persist because the team found significant differences in the amount of accumulated home value over time by neighborhood rating. We are “seeing long-lasting effects of these redlined maps on homeowners in Durham, “ said Datto, with even “significant differences between white [and non-white] homeowners, even in C and D neighborhoods.”

Zhou explained the significance of tracking the changes of each Census tract – Black, white, or integrated – over the last 50 years. The “white-black disparity [in home value] has grown by 287%” in this time period, he said. Homes of comparable structural design and apparent worth are much less valuable for simply existing in Black neighborhoods and being owned by Black people. And the problem has only expanded.

Along with differences in home value, both Black and white neighborhoods have seen a decline in Black homeowners in the 21st Century, pointing to a larger issue at hand. Though the work done so far merely documents these trends, rather than looking for correlation that may get at the underlying causes of the home-value disparity, the trends pair closely with other regions across the country being impacted by gentrification.

“Home values are going up in Black neighborhoods, but the number of Black people in those neighborhoods is going down,” said Datto.

Ali pointed out that there are evaluation practices that include evaluation of the neighborhood “as opposed to the structural properties of the home.” When a house is being evaluated, he said a home of similar structure owned by white homeowners would never be chosen as a comparator for a Latinx- or Black-owned home. This perpetuates historical disparities, as “minority neighborhoods have been historically undervalued” it is a compounding, systemic cycle.

The team hopes to export their methodology to a much larger scale. Thus far, this has presented some back-end issues with data and computer science, however “there is nothing in the analysis itself that couldn’t be [applied to other geographical locations,” they said.

Large socioeconomic racial disparities prevail in the U.S., from gaps in unemployment to infant mortality to incarceration rates to life expectancy itself. Though it should come as no surprise that home-values represent another area of inequity, work like Ali, Datto, and Zhou are conducting needs more traction, support, and expansion.

Post by Cydney Livingston

Pardon the Irruption: Winged Northern Visitors Massed for Tasty NC Mast

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One morning in November, during a visit to my parents’ house in Richmond, Virginia, I woke up to a text from my mom. “Evening Grosbeaks at the river. Want to go?” Obviously I wanted to go. I’d heard that they had left their normal range, but I was shocked that they’d made it to Richmond—Evening Grosbeaks hadn’t come this far south in decades.

Evening Grosbeaks on a feeder in Hillsborough. The males are bright (lower right), the females more understated (upper left and right). A Purple Finch (center), another northern visitor, has joined them. (Lane Scher)

This winter has been a special treat for birdwatchers—a huge “irruption” year for many northern bird species, like the Evening Grosbeak. Many irruptive species are in the finch family, which includes siskins, redpolls, crossbills and some grosbeaks. These species usually spend their winters in the northern US and Canada, but every so often they’ll journey farther south. What causes these birds to make massive flights some years and not others? It’s simple—food.

Many birds eat seeds from trees, which scientists call “mast,” in winter. But mast is produced irregularly in cycles—lots of mast one year, and little the next. Birds with irruptive migratory patterns move around to find food in winter. During years of large mast production, irruptive birds can stay in their preferred range farther north. But when food is scarce, they fly south.

Mast is an important food source not only for these irruptive bird species, but also for local bird species and mammals. In fact, mast cycles impact the entire forest food web. Years of high seed production, sometimes called “bumper crops”, lead to larger rodent populations, which then eat the eggs of songbirds. Mast might also be tied to outbreaks of tick-borne diseases like Lyme disease: rodent populations grow in big mast years, which means there are more hosts for ticks, leading to more disease.

Mast cycles can have such massive impacts on animal populations because the seed production of each tree species is synchronized across large geographic areas. That means that in one year, trees of a particular species in one area will produce many seeds, but in a neighboring region the same species might produce few seeds. These patterns create a food landscape that is dynamic across both space and time.

Ecologists want to understand how mast cycles work—and Duke is home to the founder and headquarters of MASTIF, a global network with exactly this goal. Dr. Jim Clark of the Nicholas School of the Environment wants to understand how climate drives mast cycles, and how these cycles will change under climate change. The MASTIF network is a huge collaboration that now includes over 2.5 million data points, each representing the mast produced by one tree in one year.

The Evening Grosbeak map from
Peterson’s Field Guide to Eastern Birds shows that food-seeking irruptions can indeed reach Florida, as they have this year.

As a PhD student in Dr. Clark’s lab, I’m studying the relationship between mast cycles and the bird populations they support. I want to understand how birds respond to an environment that is constantly changing—in this case, how they respond to spatial and temporal changes in food availability. This historic irruption year is a perfect example of exactly this question: a year of low mast in the north has caused bird species to travel far outside their normal range to find food.

Interestingly, the association between these irruptive birds and food availability is so strong that it can be predicted fairly easily. The Winter Finch Forecast is based on a survey of mast crops across northern North America, which is then translated into a prediction of irruption patterns. The 2020 forecast noted that Evening Grosbeak populations would be larger this year due to outbreaks of spruce budworm, an important food source during the breeding season. This increase in the population size, combined with low winter food abundance, has led to a historic flight south.

The Clark Lab’s goal of understanding and predicting mast cycles would further our knowledge of these bird species’ unique migration patterns. With a more thorough understanding of mast patterns, we could better anticipate irruptions and implement informed conservation strategies. In addition to monitoring trees in long-term forest plots, the team uses data collected by citizen scientists through the MASTIF project on iNaturalist. With over 7,000 observations from 81 people across the world, these citizen scientists have contributed a huge amount of data.

I was thrilled to see the Evening Grosbeaks in November, and I assumed it would be my only chance. But since then, they’ve been seen throughout the Carolinas and into northern Florida. Recently, a homeowner in Hillsborough spotted a group of Evening Grosbeaks in his yard. He reported them to eBird, a citizen science project that collects data from birders around the world, and that birders use to locate rare species.

Since he reported them, birders have flocked to his yard in numbers almost as stunning as the birds themselves. Over the last few weeks, he’s counted up to 60 grosbeaks on a good day, and his yard has been visited by over 250 birders. Birders don’t want to miss this—no one knows when the next big irruption will be.

Guest post by Lane Scher, a Ph.D. student in Ecology at the Nicholas School of the Environment.

Sophomore, Jonathan Carter, Investigates Different Forms of Engineering Through Research

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Conducting research is not something new for Jonathan Carter ‘23, a sophomore at Duke studying Biomedical Engineering with a minor in Visual Arts.

Carter has always questioned how things work and how to improve them. For him, nothing is impossible unless you don’t try. Born and raised in Hillsborough, North Carolina, Carter has always enjoyed spending time outdoors. In his free time, he likes to be on the water, whether it’s surfing, rowing, or just being. He has even built several boats of his own.

During Carter’s sophomore year of high school, he became interested in how waves work. The nearest beach was over two hours away and he began thinking about how and if waves could be produced closer to home. This initial curiosity led to the launch of his independent research project. 

“Sophomore year of high school, I learned about something called a hydraulic jump which is a hydraulic phenomenon, essentially fast water hits slow water and it rises, or jumps”

Learning about this phenomenon made him want to create waves of his own. He explained that if you have a flat bottom sink and you have a faucet pouring into it, a ring is created. That is essentially a small hydraulic jump. These occur naturally in rivers with an example being some types of rapids. What excited him about this was that some hydraulic jumps are actually large enough to surf them. His first application of the research was in a small creek in his backyard. The goal was to create waves in the creek large enough to surf.

“I built a down-ramp (to increase water speed) and a kicker ramp (to shape the wave)
while the water level was low” explained Carter

During a period of drought, Carter built a contraption to create hydraulic jumps, and when the river flooded, there was a small wave. While it was not large enough to surf, it was big enough for his neighbor, a small child, to boogie board on. 

At Duke he began working with a computational fluid dynamics software called Ansys.

“I use that the simulate 2d models of water flowing over a surface, like a ramp, to create hydraulic jumps” he added

After creating several 2D models he decided to take it up a notch and began producing 3D models. Currently, he is continuing his research and looking further into previous studies. The goal is to create a sustained system with a hydraulic dam to power a wave, because if he can keep the flow rate constant, it’ll make the waves smoother for surfing. This not only has applications for water sports but renewable energy as well. Waves create tremendous amounts of mechanical energy that can be harnessed into electrical energy. 

Along with his independent research, Carter is also a member of Professor George Truskey’s Lab at Duke.

One of the lab’s current themes is tissue engineering. They are working on developing human microphysiological systems (living tissue on a chip) to model normal and disease function. Carter began working in the Truskey Lab before even beginning his first year at Duke. He was interested in the research being conducted and felt that he could apply his skills to the project. He reached out to the PI via email and began working there soon after.

His work right now involves determining the effect of rheumatoid arthritis in skeletal muscles, a project led by graduate student Catherine Oliver. Duke devised a way to grow muscle cells into 3D muscle tissue called myobundles that the lab can run tests on. From there, they test myobundles with different cytokines that are relevant to rheumatoid arthritis to observe the effect.

Carter’s day-to-day work involves working with the myobundles from various donors that have been treated with different cytokines. He has to cut them up, cryosection (freeze and slice) them, stain them, image them and lastly, analyze the images for qualities like the average length of the muscle fibers.

“The myobundles themselves are really cool and I like the hands-on work. It’s almost therapeutic in a way.” Carter explained.

For Carter, working in the Truskey lab has not only taught him more about tissue engineering, but time management as well. 

He added, “I benefit from learning how to work research into my schedule because some of the things I do take a fair amount of time and some of them, like staining, have specified time limits.”

He explained that he is often working with cytokines from two donors at once. Because much of the work has time restrictions, this requires him to stay organized and plan ahead. For instance, he has to reserve his imaging equipment a week in advance and be ready to use when he needs it.

Carter is planning to remain a part of the Truskey lab for all four years at Duke. He still has some time, seeing as he is only a sophomore, but he knows he wants to pursue a career in science and to continue doing innovative research. He is most excited about advancements in space exploration and what will emerge in the next few years. While continuing his work in the Truskey lab, Carter is also planning his next steps with his wave project which involves creating more complex 3D models, connecting with other individuals to support the project, and finding a feasible location to start constructing a full-size wave this summer.

By: Anna Gotskind

Invisible No More, the Cervix

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How many people have seen their cervix? Obscured from view and stigmatized socially, the cervix is critical to women’s, transgender-men’s, and non-binary folks’ health — and potential reproductive health issues. A team formed through Duke’s Center for Global Women’s Health Technologies (GWHT) has created a device that not only holds immense medical potential but the potential to empower people with cervixes across the globe: It makes visible a previously invisible organ. 

Nimmi Ramanujam (Ph.D.), founder of GWHT and Professor of Engineering at Duke University, heads the team. Mercy Asiedu (Ph.D.), Gita Suneja (M.D.) Wesley Hogan (Ph.D.), and Andrea Kim have all been integral members of the interdisciplinary collaboration. Dr. Suneja is Associate Professor of Radiation Oncology at the University of Utah School of Medicine and a clinical researcher. Asiedu, former PhD student with Dr. Ramanujam and current postdoc at MIT, was integral to the development of Callascope.

The Callascope allows women and others who have cervixes, along with health professionals, to perform cervical exams without use of traditional examination tools that are larger, cannot be used for self-examinations, and often scary-looking.

When Wesley Hogan, director of Duke’s Center for Documentary Studies and research professor, heard about the idea “she was hooked.” Andrea Kim graduated from Duke University in 2018. Her senior thesis was a 12 minute documentary focused on the Callascope and its potential uses. Following graduation, over the last two years, she expanded the film to a 50-minute piece titled  “The (In)visible Organ” that was screened January 14, 2021. Kim moderated a panel with Ramanujam, Asiedu, Suneja and Hogan January 28th, 2021. 

Callascope: A handheld device that can be used to conduct cervical screenings. All that’s needed is a smart phone.

The Callascope addresses a dire global health need for better women’s reproductive health. Further, it empowers women as self-advocates of their own gynecological and reproductive health through reinvention of gynecological examination. Cervical cells have an “orderly progression,” says Suneja, we have a “great idea” of how cells become cancerous over time, “with multiple places to intervene.” Cervical examinations, however, are necessary for assessing cervical health and potential disease progression.

Originally from Ghana, Dr. Asiedu was interested in using her engineering skills to develop technology to “improve health outcomes,” particularly in countries like her own, which may lack adequate access to preventative healthcare and could benefit most from Callascope. Many women in underserved countries, as well as underserved areas of the United States, suffer disproportionately from cervical cancer — a preventable disease. 

Dr. Ramanujam, who served as a voluntary test-subject for Asiedu’s Callascope prototypes, says that it’s a really important tool “in actually changing [the cervix’s] narrative in a positive way” — it is an organ “that is indeed invisible.”

The hope is that with more awareness about and use of Callascope, cervical screenings, and vaginal health, cervixes may become more de-stigmatized and cultural norms surrounding them may shift to become more positive and open. Dr. Hogan stated that when Ramanujam pitched her the Callascope idea they were in a public restaurant. Hearing Ramanujam say words like “vagina” and “cervix” loud enough for others to hear made Hogan recognize her own embarrassment surrounding the topic and underscored the importance of the project. 

The project and the team serve as a wonderful example of intersectional work that bridges the sciences and humanities in effective, inspiring ways. One example was the Spring 2019 art exhibit, developed in conjunction with the team’s work, presented at the Nasher Museum which exposed the cervix through various mediums of art.

Multidisciplinary Bass Connections research teams contributed to this work and other interdisciplinary projects focused on the Callascope. Dr. Asiedu believes documentaries like Kim’s are “really powerful ways to communicate global health issues.” Kim who directed and produced “The (In)visble Organ” hopes to continue exploring how “we can create more cultures of inclusion …when it comes to reproductive health.” 

A piece of artwork from the (In)visible Organ art exhibit at Duke’s Nasher Museum in the spring of 2019.

Ramanujam emphasized the need to shift biomedical engineering focus to create technologies that center on “the stakeholders for whom [they] really [matter].” It is multi-dimensional thinkers like Ramanujam, Asiedu, Hogan, and Kim who are providing integrative and inventive ways to address health disparities of the 21st century — both the obvious and the invisible. 

Post by Cydney Livingston

Claire Engstrom, a Student Researcher Working to Treat Duchenne’s Muscular Dystrophy by Optimizing CRISPr-cas9

Meet Claire Engstrom, a Senior from Pasadena California. Claire is a Biology major who works in the Gersbach Lab at Duke. 

Claire first got involved with on-campus research through her pre-orientation program, PSearch that introduces incoming first-years to undergraduate research. Following her experience in PSearch, Claire got her first work-study research position in the Tung Lab where she worked closely with Jenny Tung, an Associate Professor in the Departments of Evolutionary Anthropology and Biology at Duke and a Faculty Associate of the Duke University Population Research Institute. 

In the Tung Lab, Claire’s research focused on how DNA methylation is passed through generations. Essentially looking at the inheritance of DNA whose methylation was impacted by environmental factors and how that affects future generations. 

Duke has research opportunities available in all disciplines as well as across departments. Approximately 53% of undergraduates graduate with research experience. Not only can students participate in groundbreaking research, but they can receive funding from the university as well to support the work they are doing.

Within the Biology department, there is a fellowship called B-SURF, the Biological Sciences Undergraduate Research Fellowship, an 8-week summer research program for rising sophomores. Claire applied for and was accepted to the fellowship and placed in one of Duke’s biomedical science laboratories. She also received a $4,000 stipend for her summer research.

Claire was placed in Charles Gersbach’s Lab focused on researching Genome Editing for Gene and Cell Therapy. Dr, Gersbach is a Rooney Family Associate Professor of Biomedical Engineering and has conducted groundbreaking work in genome editing.

Members of the Gersbach Lab in Fall 2019

Gersbach is doing research in several different domains of biomedical engineering. Claire’s project focuses on using CRISPR-Cas9, a technology that allows scientists to change an organism’s DNA using clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9. faster, cheaper, more accurate, and more efficient than other existing genome editing methods. 

Prior to joining his lab, Claire had already heard a lot about Gersbach in her course Biology 201 as well as through reading his papers. The project she would spend the next two and a half years working on focused on using and optimizing CRISPR-Cas9 to treat Duchenne’s Muscular Dystrophy and lessen the severity of the symptoms. 

Duchenne’s Muscular Dystrophy is a muscle wasting disease that affects one in every five thousand male births.

“People are diagnosed when they are around five and then they lose the ability to walk and their heart can’t pump blood because of the lack of muscles.” Claire explained.  

“CRISPR-based genome editing restores dystrophin expression in mouse models of Duchenne muscular dystrophy. Cross-sections of muscle tissue where the dystrophin protein has been labeled green, including normal, healthy tissue (left), tissue from a mouse model of Duchenne muscular dystrophy (middle), and tissue from the same mouse model that has been treated with the CRISPR gene editing system (right). Nelson et al., Science (2016)”

Thus, those affected often die in early adulthood despite current advances in cardiovascular and respiratory treatments. Duchenne’s Muscular Dystrophy generally occurs as a result of a frameshift mutation of the dystrophin gene. As a result, one’s muscles can no longer connect to anything making it nearly impossible to contract and function properly. In the Gersbach lab they are trying to treat the mutation by using CRISPR-Cas9 to remove an exon or coding region of the gene in order to shift the reading frame back into its normal place. 

This shift produces a less severe phenotype that lessens the effects of Duchenne’s Muscular Dystrophy. The result will significantly improve the quality of life and life spans for affected patients. 

Claire will be continuing her work in the Gersbach lab full time in Spring 2021 as she graduated early, with distinction in the Fall. Her thesis on the work she did in the Gersbach lab was recently approved and her results will be published in a larger paper in the future. After this year she plans to take a gap year an then return to California to hopefully attend grad school and pursue a Ph.D. in Biology.

By Anna Gotskind

Wednesdays, My New Favorite Day

After my freshman fall, I swore I’d never take another 8AM class. Yet, when a microbiology lab was the only opportunity I had for an in-person course in Duke’s disrupted Fall 2020 semester, I jumped at the chance to take it. Wednesdays have become my on-campus days, and though they start at 7AM and are often jam-packed until 7PM, they are my favorite days of the week.  

I’m usually the first to arrive in sub-basement of the Biological Sciences building on Wednesdays. As my six lab-mates join me, we stand in line on top of stickers spaced according to 6-foot social-distancing guidelines and talk about questions from class or the lab we’re going to perform that day. Sometimes it’s difficult to hear one another through our masks. When our TA is ready for us to enter the classroom, we do so one at a time, only after she’s verified our Symptom Monitoring status and taken our temperature.

Our lab stations are spaced so that we are appropriately distanced from one another, but able to work and collaborate as a team as best we can. We have a no-contact drop-zone for placing and picking up shared lab items, though each students’ space is equipped with most everything we need for our lab on most occasions. The stations are close enough so that we can chat, compare results, and ask each other for assistance as we work. Everyone wears a face shield over a face mask. Each lab session we exchange our “home” face mask for a disposable “lab” face mask. Since we work with potentially pathogenic microbes, this step is for our safety to make sure we don’t carry harmful bacteria out of our lab space. Unlike previous years, gloves are worn at all times, but the lab coats we wear have always been a standard part of the microbiology lab attire.  

The infamous “no contact drop zone” for use of shared materials during lab.

What used to be two, two-hour lab sessions twice a week has been condensed into a single four-hour lab-session to minimize exposure to one another. At the beginning of the semester it felt strange and uncomfortable to wear a mask for the whole lab period and for the rest of the day on campus. But like many changes due to Covid-19, I’ve simply gotten used to it. It’s worth it to have face-to-face interactions with fellow students and to have hands-on experience in the lab. In many ways, these experiences feel much more real and meaningful than my fully online classes, in which I interact exclusively virtually with peers and instructors.

This semester we’ve also been doing science at home, having been tasked with an independent research project to be performed outside of lab. The kitchen in my apartment has become a makeshift space for inoculating TSA plates and perplexing my roommate with my experiment.

At home experimental set-up and data collection in my apartment.

After microbiology, I grab a quick lunch at West Union…which I’m still figuring out how to navigate. There’s more online ordering and different routes for lines I haven’t gotten used to. Though it’s significantly less crowded than it used to be – which has its advantages – the energy and fervor that made up Duke is certainly missing. Though I feel it in spurts when I run into the rare upperclassman on the Plaza or in the Bryan Center while trying to find a spot to study, campus is unequivocally not the same.

I leave the central part of campus and return to the basement of BioSci to work in my research lab, the Steve Nowicki Lab. According to our Covid plan, a grad student must be present to supervise me at all times and each of us works on opposite sides of the lab space. It’s really not all that different than it used to be.

In the Nowicki Lab, I test the categorical color perception of Zebra finches. After being trained for the trials, the birds are tested to see if they can detect color differences between a background color and two “odd color out” chips. Colors one and eight are most starkly different, but when comparing colors seven and eight, for example, I sometimes struggle to tell the two colors apart.

Background color 8 versus odd-color-out 7. Can you tell the difference? (Color 7 is in wells 1 and 7)

Following a five-month hiatus from running trials, I was pleasantly surprised to find myself in the rhythm of things with only a few marginal mishaps. Within a half-hour of being back in the lab, I was running experiments at full speed again. For a moment it felt like I’d never left, and like it could have been the Wednesday before spring break, before the pandemic took full effect. Sometimes still when I’m running trials, I imagine I could walk out of BioSci’s basement and find that everything would be just as it had been when I left in March.

I spend three hours with the birds, running a refresher round followed by five experimental trials. And usually, I listen to podcasts while I work. The time passes quickly, sometimes more quickly than I’d hope.

Example of bird during experiments.

Since I’m already on campus, most Wednesdays I stick around and attend my online history seminar from a spot around campus. Though I can’t perch myself on the third floor of Perkins Library these days, I’ve found a new spot I like on the second level of the Bryan Center and I’ve made it work for me.

On Wednesdays, I am reminded of the reasons I fell in love with Duke and of all the things I miss about it in these strange and uncertain times. I wonder if the Duke I knew will ever be the same. Or if something has fundamentally shifted in our institution, and more largely in each of us individually, that only leaves us with a path forward to a new Duke, rather than a return to the old.

I am team Crystal Violet #2 and this is my bag for placing my “home mask” in when gearing up for lab.

As I return to my car in Blue Zone, I take a longing look at the Chapel. Then I make my way to my car, turn on some tunes for the drive home, and patiently wait for my alarm to wake me at 7AM the next Wednesday morning.

Most of the time I’m left thinking about the Duke that used to be, despite the fact that I certainly admire the socially-responsible and safe Duke that is. We’re doing well, all things considered. But still, it’s not the same. The Duke that the first years know is not the Duke I remember.

Post by Cydney Livingston, Trinity 2022

Saving Africa’s Biggest Trees to Help Earth Breathe

Like wine, cheese, and savvy financial investments, many tropical trees become more valuable with age. This is particularly true when it comes to carbon storage, because old trees are often the biggest trees and the larger the tree, the more carbon it stores.

The value of big, old trees in combating climate change was underscored in a recent study of Gabon’s forests, led by the Nicholas School of the Environment’s John Poulsen. The team’s striking finding — that half of Gabon’s wealth of carbon is found in the largest 5% of trees — has implications that reach far beyond the sparsely populated Central African country’s borders.

Nicholas School Ph.D. student Graden Froese admires a forest giant in Ivindo National Park, Gabon.

Tropical forests play a key role in the global carbon cycle by keeping carbon out of the atmosphere. Trees take in CO2 — one of the infamous, heat-trapping greenhouse gases — during photosynthesis and use the carbon to grow, making new leaves, thicker and taller trunks, and more expansive root systems.

Scientists can estimate how much carbon a tree holds by measuring its trunk. So, like rainforest tailors, trained technicians traveled to all corners of the country to measure the girth and height of tens of thousands of trees.

This extraordinary two-year long effort was one of the first nationwide forest inventories in the tropics, making Gabon a leader in comprehensive forest monitoring.

John Poulsen is an associate professor of tropical ecology.

Poulsen and collaborators used the tree measurements to estimate the amount of carbon stored in Gabon’s forests and to determine why some forests hold more carbon than others.

“The field techs deserve all the credit”, Poulsen explained, “as they often walked for days through thick forest, traversing swamps and enduring humid, buggy conditions to measure trees. We turned their sweat and toil into information that could be used by Gabon’s government to prioritize areas for conservation.”

Who needs ladders, when you have colleagues? The field team collaborates to measure a forest giant.

The team analyzed a suite of environmental factors to see their effects on carbon storage. Of the natural factors, only soil fertility had a noticeable positive effect on tree biomass. Much more important was the impact of humans. As human activities such as agriculture and logging tend to target large trees, more heavily human-disturbed forests had a much different structure than pristine forests. The farther a study area was from human settlements, the more likely it was to host large trees and consequently, higher amounts of carbon.

The paper notes that Gabon stands out as a country with “one of the highest densities of aboveground forest carbon.” In fact, Gabon’s undisturbed forests store more carbon than those in the Amazon, which have been referred to as the lungs of the planet.

According to Poulsen, “Gabon is the second most forested country in the world with 87% forest cover, a deforestation rate near zero…” Because of its impressive forest cover and its location straddling the equator, Gabon’s forests host an incredibly diverse array of plants and animals, including many threatened and endangered species. Rural communities depend on these forests for their livelihoods.

Unfortunately, even Gabon’s ‘small’ trees make for spectacular felled logs.

However, Gabon’s impressive forests are valuable to more than just wildlife, climate researchers, and local communities. The logging industry also sees these forests as a chance for profit. More than half (about 67%) of Gabon’s forests are under contract with logging companies to harvest timber, putting them at risk of losing many of their carbon-storing giants.

Poulsen’s study highlights the importance of a more nuanced approach to forest conservation in Gabon. One that doesn’t simply focus on stopping deforestation or promoting restoration, as is prescribed in many international climate change plans, but an approach that recognizes the necessity of preserving high conservation value, old growth forests.

Anna Nordseth

Guest Post by Anna Nordseth, a graduate student in the Nicholas School of the Environment.

Hard-Won Answer Was Worth the Wait

Most of Physics Professor Haiyan Gao’s students see their doctoral dissertations posted on her lab’s web site very soon after they have been awarded their Ph.Ds.

But Yang Zhang, Ph.D. 2018, had to wait two years, because his thesis work had a very good chance of being accepted by a major journal. And this week, it has been published in the journal Science.

What Zhang did was to create the world’s most precise value for a subatomic nuclear particle called a neutral pion. It’s a quark and an antiquark comprising a meson. The neutral pion (also known as p0) is the lightest of the mesons, but a player in the strong attractive force that holds the atom’s nucleus together.

Haiyan Gao (left) with newly-minted physics Ph.D. Yang Zhang in 2018. (Photo courtesy of Min Huang, Ph.D. ’16)

And that, in turn, makes it a part of the puzzle Gao and her students have been trying to solve for many years. The prevailing theory about the strong force is called quantum chromodynamics (QCD), and it’s been probed for years by high-energy physics. But Gao, Zhang and their collaborators are trying to study QCD under more normal energy states, a notoriously difficult problem.

Yang Zhang spent six years analyzing and writing up the data from a Primakoff  (PrimEx-II) experiment in Hall B at Thomas Jefferson National Accelerator Facility (Jefferson Lab) in Newport News, VA. His work was done on equipment supported by both the National Science Foundation and the Department of Energy.  


This is the quark structure of the positive pion – an up quark and an anti-down quark. The strong force is from gluons, represented as the wavy lines (Arpad Horvath via Wikimedia Commons)

In a Primakoff experiment, a photon beam is directed on a nuclear target, producing neutral pions. In both the PrimEx-I and PrimEx-II experiments at Jefferson Lab, the two photons from the decay of a neutral pionwere subsequently detected in an electromagnetic calorimeter. From that, Zhang extracted the pion’s ‘radiative decay width.’ That decay width is a handy thing to have, because it is directly related to the pion’s life expectancy, and QCD has a direct prediction for it.

Zhang’s hard-won answer: The neutral pion has a radiative decay width of 7.8 electron-volts, give or take. That makes it an important piece of the dauntingly huge puzzle about QCD. Gao and her colleagues will continue to ask the fundamental questions about nature, at the finest but perhaps most profound scale imaginable.

The PrimEx-I and PrimEx-II collaborations were led by Prof. Ashot Gasparian from North Carolina A&T State University. Gao and Zhang joined the collaboration in 2011.

“Precision Measurement of the Neutral Pion Lifetime,” appears in Science May 1. Dr. Yang Zhang is now a quantitative researcher at JPMorgan Chase & Co.

Students Dance Their Way Out of “AI Bias”

Martin Brooke is no ordinary Engineering professor at Duke University. He teaches computer scientists, engineers, and technology nerds how to dance.

Brooke co-teaches Performance and Technology, an interactive course where students create performance projects and discuss theoretical and historical implications of technologies in performance. In a unique partnership with Thomas DeFrantz, a professor of African and African American Studies and Dance students will design a technology based on “heart,” for example, in order to understand how human expression is embedded in technology. Two weeks later, they’ll interact with motion-sensing, robotic trees that give hugs; and 3D printed hearts that detect colors and match people, sort of like a robotic tinder.

Thomas DeFrantz (left) and Martin Brooke  watch their students perform in the Performance and Technology course .

Brooke loves that this class is fun and interactive, but more importantly he loves that this class teaches students how to consider people’s emotions, facial expressions, cultural differences, cultural similarities and interactions when designing new technologies.

Human interface is when a computerized program or device takes input from humans — like an image of a face — and gives an output — like unlocking a phone. In order for these devices to understand human interface, the programmer must first understand how humans express themselves. This means that scientists, programmers, and engineers need to understand a particular school of learning: the humanities. “There are very, very few scientists who do human interface research,” Brooke said.

The students designed a robotic “Tinder” that changes colors when it detects a match.

Brooke also mentioned the importance of understanding human expressions and interactions in order to limit computer bias. Computer bias occurs when a programmer’s prejudiced opinions of others are transferred into the computer products they design. For example, many recent studies have proven that facial recognition software inaccurately identifies black individuals when searching for suspects of a criminal case.

“It turns out one of the biggest problems with technology today is human interface,” Brooke said. “Microsoft found out that they had a motion sensitive Artificial Intelligence that tended to say women, [more often than men], were angry.”  Brooke said he didn’t consider the importance of incorporating the arts and humanities into engineering before coming to Duke. He suggested that it can be uncomfortable for some scientists to think and express themselves artistically. “[When] technologists [take Performance and Technology], for example, they are terrified of the performance aspects of it. We have some video of a guy saying, ‘I didn’t realize I was going to have to perform.’ Yeah, that’s what we were actually quite worried about, but in the end, he’s there in the video, doing slow motion running on stage — fully involved, actually performing, and really enjoying it.

Duke has a strong initiative to promote arts and humanities inclusion in science, technology, engineering, and mathematics. Brooke plans to bring Bass Connections, a research program that focuses on public outreach and cross-disciplinary work, to his Performance and Technology class before the end of the semester to demonstrate bias through a program he calls AI Bias In the Age of a Technical Elite.  

“You give it someone’s name and it will come up with a movie title, their role, and a synopsis of the movie,” Brooke said. “When I put in my name, which is an English name, it said that the movie I would be in is about a little boy who lives in the English countryside who turns into a monster and terrorizes the town.” This program shows even something as simple as a name can have so much stigma attached to it.

Bass Connections Students working on technology and engineering projects. (From the official Duke page for Bass Connections.)

Brooke’s hope is that his class teaches students to think about technology and human interface. “Hopefully that’s a real benefit to them when they get out actually designing products.”

Guest post by Jordan Anderson, a masters student in Science & Society

A Day of STEM for Girls

On any average weekday at Duke University, a walk through the Engineering Quad and down Science Drive would yield the vibrant and exciting sight of bleary-eyed, caffeine-dependent college students heading to labs or lectures, most definitely with Airpods stuck in their ears.

But on Saturday, February 22nd, a glance towards this side of campus would have shown you nearly 200 energetic and chatty female and female-identifying 4th to 6th graders from the Durham area. As part of Capstone, an event organized by Duke FEMMES, these students spent the day in a series of four hands-on STEM activities designed to give them exposure to different science, technology, engineering, and math disciplines.

Nina MacLeod, 10, gets grossed out when viewing fruit fly larvae through a microscope while her guide, Duke first-year Sweta Kafle, waits patiently. (Jared Lazarus)

FEMMES, which stands for Females Excelling More in Math, Engineering, and Science, is an organization comprised of Duke students with the aim of improving female participation in STEM subjects. Their focus starts young: FEMMES uses hands-on programming for young girls and hosts various events throughout the year, including after-school activities at nearby schools and summer camps. 

Capstone was a day of fun STEM exposure divided into four events stationed along Science Drive and E-Quad — two in the morning, and two in the afternoon, with a break for lunch. Students were separated into groups of around eight, and were led by two to three Duke undergraduates and a high school student. The day started bright and early at 8:45 A.M with keynote speaker Stacy Bilbo, Duke professor of Psychology and Neuroscience. 

Staci Bilbo

Bilbo explained that her work centers around microglial cells, a type of brain cell. A series of slides about her journey into a science career sparked awe, especially as she remarked that microglial cells are significant players in our immune system, but scientists used to know nearly nothing about them. Perhaps most impactful, however, was a particular slide depicting microglial cells as macrophages, because they literally eat cellular debris and dead neurons.

A cartoon depiction of this phenomenon generated a variety of reactions from the young audience, including but not limited to: “I’m NEVER being a doctor!”, “I wish I was a microglial cell!”, “Ew, why are brains so gross?”, and “I’m so glad I’m not a brain because that’s SO weird.”

Even in 2020, while fields like medicine and veterinary science see more women than men, only 20% of students that earn bachelor’s degrees in physical sciences, math, and engineering disciplines are female. What accounts for the dramatic lack of female participation in STEM disciplines? The reasons are nuanced and varied. For example, according to a 2010 research report by the American Association of University Women, girls tend to have more difficulty acquiring spatial thinking and reasoning skills – all because of the type of play young female children are more likely to engage in. 

Durham area students learned how to perform a blood pressure check during a FEMMES session taught by Duke EMS, an all-volunteer, student-run division of the police department and Duke Life Flight. Duke senior Kayla Corredera-Wells (center) put the blood pressure cuff on sophomore Pallavi Avasarala. (Jared Lazarus)

This creates a chicken-and-egg story: girls don’t enter STEM at the same rate as their male counterparts, and as a result, future generations of girls are discouraged from pursuing STEM because they don’t see as many accomplished, visibly female scientists to look up to. Spaces like Capstone which encourage hands-on activity are key to exposing girls to the same activities that their male counterparts engage in on a regular basis – and to exposing girls to a world of incredible science and discovery led by other females. 

After Bilbo’s talk, it was off to the activities, led by distinguished female professors at Duke — a nod to the importance of representation when encouraging female participation in science. For example, one of the computer science activities, led by Susan Rodger, taught girls how to use basic CS skills to create 3-D interactive animation.

An introduction to categorizing different minerals based on appearance was led by Emily Klein, while one of the medicine-centered activities involved Duke EMS imparting first aid skills onto the students. 

For one of the biology-themed activities, Nina Sherwood and Emily Ozdowski (dubbed “The Fly Ladies”) showed students fruit flies under a microscope. The activity clearly split the group: girls who stared in glee at unconscious flies, shrieking “It’s SO BIG, look at it!” and girls who exchanged disgusted looks, edging their swivel chairs as far as physically possible from the lab benches. Elizabeth Bucholz, a Biomedical Engineering professor, led one of the engineering activities, showing students how CT scans generate images using paper, a keychain light and a block (meant to represent the body). In math, meanwhile, Shira Viel used the activity of jump-roping to show how fractions can untangle the inevitable and ensuing snarls.

The day definitely wasn’t all science. During lunch in LSRC’s Love Auditorium, most groups spread out after scarfing down pizza and spent intense focus over learning (and recording) TikTok dances, and when walking down Science Drive under blue and sunny skies, conversations ranged from the sequins on someone’s Ugg boots to how to properly bathe one’s dog, to yelling erupting over someone confidently proclaiming that they were a die-hard Tar Heel.

Nina Sherwood, Associate Professor of Biology, showed Emma Zhang, 9, some fruit flies, which we study because they share 75% of their genes with humans. (Jared Lazarus)

A raffle at the end of the day for the chance to win Duke merchandise inspired many closed eyes and crossed fingers (“I want a waterbottle so bad, you have no idea!”) And as newfound friends said goodbye to each other and wistfully bonded over how much fun they had at the end of the day, one thing was clear: events like Capstone are crucial to instilling confidence and a love of STEM in girls. 

By Meghna Datta

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