About 70% of the human body is made up of water. Water is something we consume on a daily basis. Therefore, when a community’s water source is threatened or contaminated it can be extremely detrimental.
In 2017, it became apparent that there was water contamination in eastern North Carolina. Specifically, PFAS or per- and polyfluoroalkyl Alkyl chemicals were found in the water supply. As a result, several legislative mandates were issued in 2018 establishing a PFAS Testing Network to investigate the contamination.
Lee Ferguson, an Associate Professor of Civil and Environmental Engineering at Duke and Kathleen Gray, a professor at UNC’s Institute for the Environment, are testing PFAS water contamination and communicating any risks to the public.
Gray is part of the network’s risk communication team. She explained that PFASs are hard to address because the health effects are unknown and they have yet to determine a standard or guideline for these substances. However, because this water contamination affects the lives of everyone connected to the water supply it is extremely important to communicate risk to the affected community but without eliciting panic.
Gray explained that people often ask, “Are my family and I safe?” “What can I do to protect myself and my family?” “Why did this happen?” and “Why wasn’t it prevented?”
In the last year Ferguson and his research team have tested 409 sites in North Carolina for PFAS compounds.
He explained that PFAS substances are particularly dangerous because they are non-degradable, potentially toxic and constantly changing. Long-chain PFASs are being replaced by fluorinated alternatives.
Ferguson described this phenomenon as “playing environmental ‘whack-a-mole’ with different substances.”
Ferguson and his testing team have found two contaminated water supply sites in North Carolina. Dangerous contamination is based on the EPA health advisory level of 70ng/Liter. The exceedances were found in Maysville and Orange Water and Sewer Authority. Maysville was able to switch to the Jones County water source once the problem was identified.
New data that came in within the last couple weeks found high month-to-month variability in PFAS in the Haw River near Pittsboro. Ferguson and his team predict that it is coming downstream from a waste treatment plant.
Brunswick County is shown having the worst PFAS concentrations. However, Dr. Ferguson and his team have recently found that the contamination in Haw River is even worse.
While all of this information may seem very alarming, Gray and Ferguson both reiterated that it is not necessary to panic. Instead, people should make sure they are drinking filtered water or invest in a water filter.
Ferguson added, “The best choice is reverse osmosis.”
Gray and Ferguson presented their work at a SciComm Lunch-and-Learn, a monthly event sponsored by Duke Science & Society Initiative that explores interesting and innovative aspects of science communication. The event is free and open to anyone in the Duke community.
It’s been over three years since the National Museum of African American History & Culture (NMAAHC) opened in D.C. in September 2016, but the excitement around it doesn’t seem to have dimmed much. Chances are, you’re going to have to get your tickets three months in advance if you want to visit. Infants need their own timed pass, too.
The National Museum of African American History and Culture. Photo courtesy of Prabal Tiwari
On Friday, January 17, Duke’s From Slavery to Freedom Lab hosted a panel in conjunction with the Franklin Humanities Institute on the topic of contemporary Black arts and icons. The panel, “New Black Aesthetics,” featured speakers Rhea L. Combs, curator at the National Museum of African American & Culture, and Richard J. Powell, John Spencer Bassett Professor of Art & Art History at Duke, and was one half of a two-panel conference titled “Black Images, Black Histories.”
According to Combs and Powell, the reason for the unprecedented popularity of works like the NMAAHC by contemporary Black artists is likely because they do something that other pieces and people rarely do: allow African Americans to tell the African American story.
As a museum curator, Combs doesn’t simply curate cohesive mixed-media exhibitions that shed light on the Black experience. In order to create those exhibitions, she must also dig through and analyze a wide range of old archival materials.
Rhea L. Combs, Curator at the NMAAHC. Photo courtesy of the Smithsonian
However, these archival materials at the NMAAHC aren’t necessarily just historical artifacts and records associated with figures like Rosa Parks or the Obamas; the Museum wants people to shuffle through their own attics to find things to donate. It demystifies the question of who belongs in a museum, according to Combs. “We create agency in terms of who gets to tell everyday stories,” she said.
She’s especially interested in the role of photography and film in African American studies. “We use cameras to culturally agitate the ways in which African Americans are understood,” she explained; the camera is a pathway into self-representation.
Captured in the Museum’s photos and moving images are stories of duplicity, or “celebrations that happened in the midst of tragedies.” Combs often finds themes of faith and activism as well as education and uplift, but she says that there’s plenty of variety within those overarching ideas. A photo of boys playing basketball on unicycles, for example.
“Art creates social understanding of who we are,” Combs said. Like hip-hop remixes and re-envisions things that are already understood in one way, so too does the NMAAHC.
On a similar vein, Powell’s presentation focused on the famous Obama portraits, and I’m guessing you might already know which ones I’m referring to. A fully-suited Barack Obama, seated in a wooden chair against a lush green background of flora and fauna; Michelle Obama in a flowing black-and-white colorblock dress, her chin resting on the back of her hand.
Powell examines how these portraits, simply titled “President Barack Obama” and “First Lady Michelle Obama,” manage to blend visual elements with socio-historical allusions and contexts to become world-famous 21st-century icons.
Richard J. Powell, Professor of Art and Art History at Duke.
While the portraits are visually exceptional, Powell said their context is what envelops. These images of the first Black U.S. president and first lady do allude to the old, white traditions of portraiture, “but they dismantle the genre’s conventional outcomes” for something new, he explained.
The portrait of Barack Obama is, visually, extremely similar to those of Abraham Lincoln and Franklin Delano Roosevelt. Likewise, Michelle Obama’s portrait quite closely resembles that of Madame Moitessier, for example. But unlike these representations of pre-21st-century white men and women, the Obama portraits finally depict people of color. According to Powell, portraits elevate status, and it isn’t very often that you see Black individuals portrayed.
And yet there’s also a sad irony involved, Powell explained. Especially for other similar contemporary works of portraiture that depict Black people, there’s a decorative, incongruous grandeur that highlights the tension between social realities and the manner of portrayal. For instance, “saintly” portraits exist of Black men wearing urban clothing, but despite whatever “saintliness” might be visually depicted, the realities of Blackness in the inner cities of America is often far from positive.
One of the most striking features of the Barack Obama portrait is the blooming greenery behind the former president. It’s a metaphor of sorts, Powell said: social and historical context isn’t absent from art. Or, in other words, “The world can never be left out of the garden.”
This is the sixth and final 2019 post written by students at the North Carolina School of Science and Math as part of an elective about science communication with Dean Amy Sheck.
Dr. Patrick Codd is the Director of the Duke Brain Tool Laboratory and an Assistant Professor of Neurosurgery at Duke. Working as a neurosurgeon and helping with the research and development of various neurosurgical devices is “a delicate balance,” he said.
Patrick Codd
Codd currently runs a
minimally invasive neurosurgery group. However, at Massachusetts General
Hospital, he used to run the trauma section. When asked about which role was
more stressful, he stated “they were both pretty stressful” but for different
reasons. At Mass General, he was on call for most hours of the day and had to
pull long shifts in the operating room. At Duke, he has to juggle surgery,
teaching, and research and the development of new technology.
“I didn’t know I was
going to be a neurosurgeon until I was in college,” Codd said. Despite all of
the interesting specialties he learned about in medical school, he said “it was
always neurosurgery that brought me back.”
Currently, he is
exclusively conducting cranial surgery.
Neurosurgeon U.S. Air Force Maj Jonathan Forbes,looks through loupes as he performs brain surgery at the Bagram Air Field in Afghanistan, Oct. 10, 2014.
Though Dr. Codd has earned
many leadership positions in his career, he said he was never focused on advancement.
He simply enjoys working on topics which he loves, such as improving minimally
invasive surgical techniques. But being in leadership lets him unite other
people who are interested in working towards a common goal in research and
development. He has been able to skillfully bring people together from various
specialties and help guide them. However, it is difficult to meet everyone’s
needs all of the time. What is important for him is to be a leader when he
needs to be.
Dr. Codd said there are typically five to eight research papers necessary in to lay the groundwork for every device that is developed. However, some technologies are based on the development of a single paper. He has worked on devices that make surgery more efficient and less minimally invasive and those that help the surgical team work together better. When developing technologies, he tries to keep the original purpose of the devices the same. However, many revisions are made to the initial design plans as requirements from the FDA and other institutions must be met. Ironically, Dr. Codd can’t use the devices he develops in his own operating room because it would be a conflict of interest. Typically other neurosurgeons from across the country will use them instead.
This is the fourth of several posts written by students at the North Carolina School of Science and Math as part of an elective about science communication with Dean Amy Sheck.
Dr. Giny Fouda’s research focuses on
infant immune responses to infection and vaccination.
Her curiosity about immunology arose during her fourth year of medical school in Cameroon, when she randomly picked up a book on cancer immunotherapy and was captivated. Until then, she conducted research on malaria and connected it to her interest in pediatrics by studying the effects of the parasitic disease on the placentas of mothers.
Genevieve Giny Fouda M.D., Ph.D.
As a postdoctoral fellow at Duke, she
then linked pediatrics and immunology to begin examining mother to child
transmission of disease and immunity.
Today she is an M.D. and a Ph.D. and a
member of the Duke Human Vaccine Institute. She’s an assistant professor in
pediatrics and an assistant research professor in the Department of Molecular Genetics
and Microbiology at Duke University School of Medicine.
Based on the recent finding that children of HIV-positive mothers are more susceptible to inheriting the disease, Fouda believes that it is important to understand how to intervene in passive immunity transmissions in order to limit them. Children and adults recover from diseases differently and uncovering these differences is important for vaccine development.
This area of research is personally important to her, because she learned from her service in health campaigns in Central Africa that it is much easier to prevent disease than to treat.
Babies!
However, she believes that it is important to recognize that research is a collaborative experience with a team of scientists. Each discovery is not that of an individual, but can be accredited to everyone’s contribution, especially those whose roles may seem small but are vital to the everyday operations of the lab.
At the Duke Human Vaccine Institute, Fouda enjoys collaborating as a team and contributing her time as a mentor and trainer of young scientists in the next generation.
Outside of the lab, Fouda likes to spend time reading books with her daughter, traveling, decorating and gardening. If there was one factor that improve how science in immunology is conducted, she would stress that preventing disease is significantly cheaper than treating those that become infected by it.
Dr. Fouda has made some remarkable progress in the field of disease treatment with her hard working and optimistic personality, and I know that she will continue to excel in her objectives for years to come.
This is the third of several posts written by students at the North Carolina School of Science and Math as part of an elective about science communication with Dean Amy Sheck.
Beneath Duke University’s Perkins library,
an unassuming, yet fiercely original approach to video games research is
underway. Tied less to computer science and engineering than you might expect,
the students and faculty are studying games for their effects on players.
I was introduced to a graduate researcher who
has turned a game into an experiment. His work exists between the humanities,
psychology, and computer science. Some games, particularly modern ones, feature
complex economies that require players to collaborate as often as they compete.
These researchers have adapted that property to create an economics game in
which participants anonymously affect the opportunities – and setbacks – of
other players. Wealth inequality is built in. The players’ behavior, they hope,
will inform them about ‘real-world’ economic decisions.
Shai Ginsburg playing
At the intersection of this
interdisciplinary effort with games, I met Shai Ginsburg, an associate professor in the
department of Asian and Middle Eastern studies who studies video games and
board games the way other humanities professors might study Beowulf.
For example, he is able to divide human history
into eras of games rather than of geopolitics.
“Until recently, games were not all that
interactive,” he says. “Video games are, obviously, interactive, but board
games have evolved, too, over the same period of time.” This shift is
compelling because it offers us new freedoms in the way we express human
experience.
A new gaming suite at Lawrence Tech University in Southfield, Mich. (LTU/Matt Roush)
“The fusion of storytelling and
interactivity in games is very compelling,” Ginsburg says. “We haven’t seen
that many games that handle issues like mental illness,” until more recently,
he points out. The degree of interactivity in a video game grants a player a
closeness to the narrative in the areas where writing, music, and visual art
alone would be restricted. This closeness gives game designers – as artists –
the freedom to explore themes where those artistic restrictions also hinder
communication.
However, Dr. Ginsburg is not a game
historian; the time that a game feature evolved is far less relevant to him than
how its parent game affects players. “We tend to focus on the texts that
interest us in a literature class,” he says, by way of example. He studies the
games that interest him for the play opportunities they provide.
One advantage of using games as a medium
to study their effects on people is that, “the distinction between highbrow and
lowbrow is not yet there,” Ginsburg says. In painting, writing, and plenty of
other mediums, a clear distinction between “good” and “bad” is decided
simultaneously by communities of critics and consumers. Not so, in the case of
games.
“I look at communities as a measure of the effectivity of the game less than for itself,” Ginsburg notes. “I think the question is ‘how was I reacting?’ and ‘why was I reacting in such a way?’” he says. Ginsburg’s effort seeks to reveal the mechanisms that give games their societal impact, though those impacts can be elusive. How to learn more? “Play lots of games. Play different kinds of games. Play more games.”
This is the second of several posts written by students at the North Carolina School of Science and Math as part of an elective about science communication with Dean Amy Sheck.
As an occasional volunteer at a local children’s museum, I
can tell you that children take many different approaches to sharing. Some will
happily lend others their favorite toys, while others will burst into tears at
the suggestion of giving others a turn in an exhibit.
For Rita Svetlova Ph.D. at the Duke Empathy Development Lab, these behaviors aren’t just passing observations, they are her primary scientific focus. In November, I sat down with Dr. Svetlova to discuss her current research, past investigations, and future plans.
Margarita Lvovna Svetlova
Originally from Russia, Svetlova obtained an M.A. from
Lomonosov Moscow State University in Moscow before earning her Ph.D in
developmental psychology from the University of Pittsburgh. She later worked as
a post-doctoral researcher at the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany.
Now at Duke University as an assistant research professor of psychology and neuroscience and the principal investigator in the Empathy Development Lab, Svetlova looks at the development of ‘prosocial’ behavior in children — behaviors such as sharing, empathy, and teamwork.
Svetlova credits her mentor at the University of Pittsburgh,
Dr. Celia Brownell, for inspiring her to pursue child psychology and
development. “I’ve always been interested in prosociality, but when I was in
Russia I actually studied linguistics,” she says. “When I moved to the U.S., I
changed paths partly because I’ve always wanted to know more about human
psychology. The reason I started studying children is partly because I was
interested in it and partly because I met Dr. Brownell. I branched out a little
bit, but I generally found it interesting.”
An unsuccessful sharing experience. (From Awkward Family Photos)
Although her passion for childhood development research
began in Pittsburgh, Svetlova has
embraced her role as a Duke researcher, most recently tackling a scenario that
most academically-inclined readers are familiar with — a partner’s failure to
perform in a joint-commitment — in a co-authored May 2017 paper titled
“Three-Year-Olds’ Reactions to a Partner’s Failure to Perform Her Role in a
Joint Commitment.”
In
the study, 144 three-year-olds were presented with a common joint commitment
scenario: playing a game. For one third of the children, the game ended when
their partner defected, while another third of the test group had a partner who
didn’t know how to play. The final third
of the group saw the game apparatus break. Svetlova looked at how the
children’s reactions varied by scenario: protesting defectors, teaching the
ignorant partner, and blaming the broken apparatus. The results seem to suggest
that three-year-olds have the ability to evaluate intentions in a joint
commitment.
Another
paper Svetlova co-authored, titled “Three- and 5-Year-Old Childrens’ Understanding
of How to Dissolve a Joint Commitment,” compared the reactions of three- and
five-year-olds when a puppet left a collaborative game with either permission,
prior notification, or suddenly without prior notification. If the puppet left
without warning, three-year-old subjects protested more and waited longer for
the puppet’s return, but both age groups seemed to understand the agreement implicit
in a joint commitment.
These
joint commitments are only a small fraction of the questions that Svetlova
hopes to address.
“A
longitudinal study of prosociality would be amazing,” she says. “What I’m
interested in now is the intersection of fairness understanding and
in-group/out-group bias. What I am trying to look into is how children
understand their in-group members vs. out-group members and whether there’s
something we can do to make them more accepting of their out-group members.”
“Another
one I am interested in is the neural basis of empathy and prosocial behavior. I
haven’t started yet, but I’m planning a couple of studies on looking into the
brain mechanisms of empathy in particular,” Svetolova says. “We plan to scan
children and adults while experiencing an emotion themselves and compare that
brain activation to the brain activation while witnessing someone experiencing
an emotion, the question being ‘do we really feel others’ emotions as our
own?’”
Svetlova
also expressed her interest in the roles that gender, culture, and upbringing
play in a child’s development of prosociality.
I
had to ask her why teenagers seemed to “regress” in prosociality, seemingly
becoming more selfish when compared to their childhood selves.
“I would distinguish between self-centered and selfish,” she assured me. “You are not necessarily selfish, it’s just that during teenagehood you are looking for your place in the world, in the ‘pack.’ That’s why these things become very important, other’s opinions about you and your reputation in this little group, people become very anxious about it, it doesn’t mean that they become selfish all of a sudden or stop being prosocial.” She added, “I believe in the good in people, including teenagers.”
This is the first of several posts written by students at the North Carolina School of Science and Math as part of an elective about science communication with Dean Amy Sheck.
Claudia Gunsch, the Theodore Kennedy distinguished associate professor in the department of civil and environmental engineering, wants to know how to engineer a microbial community. An environmental engineer with a fascination for the world at the micro level, Gunsch takes a unique approach to solving the problem of environmental pollution: She looks to what’s already been done by nature.
Claudia Gunsch, Ph.D.
Gunsch and her team seek to harness the power of microbes to create living communities capable of degrading contamination in the environment.
“How can you engineer that microbial community so the
organisms that degrade the pollutant become enriched?” she asks. “Or — if
you’re thinking about dangerous pathogenic organisms — how do you engineer the
microbial community so that those organisms become depressed in that particular
environment?”
The first step, Gunsch says, is to figure out who’s there.
What microbes make up a community? How do these organisms function? Who is
doing what? Which organisms are interchangeable? Which prefer to live with one
another, and which prefer not living with one another?
“Once we can really start building that kind of framework,”
she says, “we can start engineering it for our particular purposes.”
Yet identifying the members of a microbial community is far
more difficult than it may seem. Shallow databases coupled with vast variations
in microbial communities leave Gunsch and her team with quite a challenge.
Gunsch, however, remains optimistic.
Map of U.S. Superfund Sites (2013)
“The exciting part is that we have all these technologies
where we can sequence all these samples,” she says. “As we become more
sophisticated and more people do this type of research, we keep feeding all of
this data into these databases. Then we will have more information and one day,
we’ll be able to go out and take that sample and know exactly who’s there.”
“Right now, it’s in its infancy,” she says with a smile.
“But in the long-term, I have no doubt we will get there.”
Gunsch is currently working on Duke’s Superfund Research
Center designing bioremediation technologies for the degradation of polycyclic
aromatic hydrocarbon (PAH) contamination. These pollutants are extremely
difficult to break down due to their tendency to stick strongly onto soil and
sediments. Gunsch and her team are searching for the right microbial community
to break these compounds down — all by taking advantage of the innate
capabilities of these microorganisms.
A photo montage from Dr. Gunsch’s lab page.
Step one, Gunsch says, has already been completed. She and
her team have identified several different organisms capable of degrading PAHs.
The next step, she explains, is assembling the microbial communities — taking
these organisms and getting them to work together, sometimes even across
kingdoms of life. Teamwork at the micro level.
The subsequent challenge, then, is figuring out how these
organisms will survive and thrive in the environment they’re placed in, and
which microbial seeds will best degrade the contamination when placed in the
environment. This technique is known as “precision bioremediation” — similar to
precision medicine, it involves finding the right solution in the right amounts
to be the most effective in a certain scenario.
“In this particular case, we’re trying to figure out what
the right cocktail of microbes we can add to an environment that will lead to
the end result that is desired — in this case, PAH degradation,” Gunsch says.
Ultimately, the aim is to reduce pollution and restore
ecological health to contaminated environments. A lofty goal, but one within
sight. Yet Gunsch sees applications beyond work in the environment — all work dealing
with microbes, she says, has the potential to be impacted by this research.
“If we understand how these organisms work together,” she says, “then we can advance our understanding of human health microbiomes as well.”
‘T-Ray’ laser finally arrives in practical, tunable form. Duke physicist Henry Everitt worked on it over two decades. Courtesy of Chad Scales, US Army Futures Command
It was a Frankenstein moment for Duke alumnus and adjunct physics professor Henry Everitt.
After years of working out the basic
principles behind his new laser, last Halloween he was finally ready to put it
to the test. He turned some knobs and toggled some switches, and presto, the
first bright beam came shooting out.
“It was like, ‘It’s alive!’” Everitt said.
This was no laser for presenting Powerpoint slides or entertaining cats. Everitt and colleagues have invented a new type of laser that emits beams of light in the ‘terahertz gap,’ the no-man’s-land of the electromagnetic spectrum between microwaves and infrared light.
Terahertz radiation, or ‘T-rays,’ can see
through clothing and packaging, but without the health hazards of harmful
radiation, so they could be used in security scanners to spot concealed weapons
without subjecting people to the dangers of X-rays.
It’s also possible to identify substances by
the characteristic frequencies they absorb when T-rays hit them, which makes
terahertz waves ideal for detecting toxins in the air or gases between the
stars. And because such frequencies are higher than those of radio waves and
microwaves, they can carry more bandwidth, so terahertz signals could transmit
data many times faster than today’s cellular or Wi-Fi networks.
“Imagine a wireless hotspot where you could
download a movie to your phone in a fraction of a second,” Everitt said.
Yet despite the potential payoffs, T-rays
aren’t widely used because there isn’t a portable, cheap or easy way to make
them.
Now Everitt and colleagues at Harvard University and MIT have invented a small, tunable T-ray laser that might help scientists tap into the terahertz band’s potential.
While most terahertz molecular lasers take up
an area the size of a ping pong table, the new device could fit in a shoebox.
And while previous sources emit light at just one or a few select frequencies,
their laser could be tuned to emit over the entire terahertz spectrum, from 0.1
to 10 THz.
The laser’s tunability gives it another
practical advantage, researchers say: the ability to adjust how far the T-ray
beam travels. Terahertz signals don’t go very far because water vapor in the
air absorbs them. But because some terahertz frequencies are more strongly
absorbed by the atmosphere than others, the tuning capability of the new laser
makes it possible to control how far the waves travel simply by changing the
frequency. This might be ideal for applications like keeping car radar sensors
from interfering with each other, or restricting wireless signals to short
distances so potential eavesdroppers can’t intercept them and listen in.
Everitt and a team co-led by Federico Capasso of Harvard and Steven Johnson of MIT describe their approach this week in the journal Science. The device works by harnessing discrete shifts in the energy levels of spinning gas molecules when they’re hit by another laser emitting infrared light.
Their T-ray laser consists of a pencil-sized
copper tube filled with gas, and a 1-millimeter pinhole at one end. A zap from the
infrared laser excites the gas molecules within, and when the molecules in this
higher energy state outnumber the ones in a lower one, they emit T-rays.
The team dubbed their gizmo the “laughing gas
laser” because it uses nitrous oxide, though almost any gas could work, they
say.
Duke professor Henry Everitt and MIT graduate student Fan Wang and colleagues have invented a new laser that emits beams of light in the ‘terahertz gap,’ the no-man’s-land of the electromagnetic spectrum.
Everitt started working on terahertz laser designs 35 years ago as a Duke undergraduate in the mid-1980s, when a physics professor named Frank De Lucia offered him a summer job.
De Lucia was interested in improving special
lasers called “OPFIR lasers,” which were the most powerful sources of T-rays at
the time. They were too bulky for widespread use, and they relied on an equally
unwieldy infrared laser called a CO2 laser to excite the gas inside.
Everitt was tasked with trying to generate
T-rays with smaller gas laser designs. A summer gig soon grew into an
undergraduate honors thesis, and eventually a Ph.D. from Duke, during which he
and De Lucia managed to shrink the footprint of their OPFIR lasers from the
size of an axe handle to the size of a toothpick.
But the CO2 lasers they were
partnered with were still quite cumbersome and dangerous, and each time
researchers wanted to produce a different frequency they needed to use a different
gas. When more compact and tunable sources of T-rays came to be, OPFIR lasers
were largely abandoned.
Everitt would shelf the idea for another
decade before a better alternative to the CO2 laser came along, a
compact infrared laser invented by Harvard’s Capasso that could be
tuned to any frequency over a swath of the infrared spectrum.
By replacing the CO2 laser with
Capasso’s laser, Everitt realized they wouldn’t need to change the laser gas anymore
to change the frequency. He thought the OPFIR laser approach could make a
comeback. So he partnered with Johnson’s team at MIT to work out the theory,
then with Capasso’s group to give it a shot.
The team has moved to patent their design,
but there is still a long way before it finds its way onto store shelves or
into consumers’ hands. Nonetheless, the researchers — who couldn’t resist a
laser joke — say the outlook for the technique is “very bright.”
This research was supported by the U.S. Army Research Office (W911NF-19-2-0168, W911NF-13-D-0001) and by the National Science Foundation (ECCS-1614631) and its Materials Research Science and Engineering Center Program (DMR-1419807).
CITATION: “Widely Tunable Compact Terahertz Gas Lasers,” Paul Chevalier, Arman Armizhan, Fan Wang, Marco Piccardo, Steven G. Johnson, Federico Capasso, Henry Everitt. Science, Nov. 15, 2019. DOI: 10.1126/science.aay8683.
The proton, that little positively-charged nugget inside
an atom, is fractions of a quadrillionth of a meter smaller than anyone thought,
according to new research appearing Nov. 7 in Nature.
Haiyan Gao of Duke Physics
In work they hope solves the contentious “proton radius puzzle” that has been roiling some corners of physics in the last decade, a team of scientists including Duke physicist Haiyan Gao have addressed the question of the proton’s radius in a new way and discovered that it is 0.831 femtometers across, which is about 4 percent smaller than the best previous measurement using electrons from accelerators. (Read the paper!)
A single femtometer is 0.000000000000039370 inches
imperial, if that helps, or think of it as a millionth part of a billionth part
of a meter. And the new radius is just 80 percent of that.
But this is a big — and very small — deal for
physicists, because any precise calculation of energy levels in an atom will be
affected by this measure of the proton’s size, said Gao, who is the Henry
Newson professor of physics in Trinity College of Arts & Sciences.
Bohr model of Hydrogen. One proton, one electron, as simple as they come.
What the physicists actually measured is the radius of
the proton’s charge distribution, but that’s never a smooth, spherical point,
Gao explained. The proton is made of still smaller bits, called quarks, that
have their own charges and those aren’t evenly distributed. Nor does anything
sit still. So it’s kind of a moving target.
One way to measure a proton’s charge radius is to scatter
an electron beam from the nucleus of an atom of hydrogen, which is made of just
one proton and one electron. But the electron must only perturb the proton very
gently to enable researchers to infer the size of the charge involved in the
interaction. Another approach measures the difference between two atomic
hydrogen energy levels. Past results from these two methods have generally
agreed.
Artist’s conception of a very happy muon by Particle Zoo
But in 2010, an experiment at the Paul Scherrer Institute replaced the electron in a hydrogen atom with a muon, a much heavier and shorter-lived member of the electron’s particle family. The muon is still negatively charged like an electron, but it’s about 200 times heavier, so it can orbit much closer to the proton. Measuring the difference between muonic hydrogen energy levels, these physicists obtained a proton charge radius that is highly precise, but much smaller than the previously accepted value. And this started the dispute they’ve dubbed the “proton charge radius puzzle.”
To resolve the puzzle, Gao and her collaborators set out
to do a completely new type of electron scattering experiment with a number of
innovations. And they looked at electron scattering from both the proton and
the electron of the hydrogen atom at the same time. They also managed to get
the beam of electrons scattered at near zero degrees, meaning it came almost
straight forward, which enabled the electron beam to “feel” the proton’s charge
response more precisely.
Voila, a 4-percent-smaller proton. “But actually, it’s
much more complicated,” Gao said, in a major understatement.
The work was done at the Department of Energy’s Thomas
Jefferson National Accelerator Facility in Newport News, Virginia, using new
equipment supported by both the National Science Foundation and the Department
of Energy, and some parts that were purpose-built for this experiment. “To
solve the argument, we needed a new approach,” Gao said.
Gao said she has been interested in this question for nearly
20 years, ever since she became aware of two different values for the proton’s
charge radius, both from electron scattering experiments. “Each one claimed about 1 percent
uncertainty, but they disagreed by several percent,” she said.
And as always in modern physics, had the answer not
worked out so neatly, it might have called into question parts of the Standard
Model of particle physics. But alas, not this time.
“This is particularly important for a number of reasons,”
Gao said. The proton is a fundamental building block of visible matter, and the
energy level of hydrogen is a basic unit of measure that all physicists rely
on.
The new measure may also help advance new insights into
quantum chromodynamics (QCD), the theory of strong interaction in quarks and
gluons, Gao said. “We really don’t understand how QCD works.”
“This is a very, very big deal,” she said. “The field is
very excited about it. And I should add that this experiment would not have
been so successful without the heroic contributions from our highly talented
and hardworking graduate students and postdocs from Duke.”
This work was funded in part by the U. S. National Science Foundation (NSF MRI PHY-1229153) and by the U.S. Department of Energy (Contract No. DE-FG02-03ER41231), including contract No. DE-AC05-06OR23177 under which Jefferson Science Associates, LLC operates Thomas Jefferson National Accelerator Facility.
CITATION: “A Small Proton Charge Radius from An Electron-Proton Scattering Experiment,” W. Xiong, A. Gasparian, H. Gao, et al. Nature, Nov. 7, 2019. DOI: 10.1038/s41586-019-1721-2 (ONLINE)
According to Professor Deonte Harris, many of us here in the U.S. have a fascination with Black music. But at the same time, we tend not to realize that it’s. . . well, Black music.
Deonte Harris, Ph.D., Assistant Professor of the Practice of the International Comparative Studies Program
He chose to conduct his research in the UK because of its large overseas Caribbean population and because he found that not much scholarship was dedicated to Black Europe. “It’s such a rich space to think about different historical entanglements that affect the lives and trajectories of Black people,” he explained.
Those entanglements include the legacies of colonialism, the Slave Trade, empire, and much more. The racialization of such historical processes is necessary to note.
For example, Harris found that a major shift in Black British music occurred in the 1950s due to anti-Black racism in England. Black individuals were not allowed to socialize in white spaces, so they formed community in their own way: through soundsystems.
These soundsystem originated in Jamaica and debuted in the UK in the postwar years. A soundsystem was the organization of Black individuals, music, and machines, typically in basements and warehouses, for the enjoyment of Black music and company. It became a medium through which a Black community could form in a racialized nation.
Notting Hill Carnival, London: An annual celebration of Black British culture. Photo by Dominic Alves.
Today, Black British music has greatly expanded, but still remains rooted in sound systems.
While the formation of community has been positive, Harris explains that much of his research is a highly complex and often disheartening commentary on Blackness.
Blackness has been created as a category by dominant society: the white community, mostly colonizers. Black music became a thing only because of the push to otherize Black Britons; in many ways, Black culture exists only as an “other” in relation to whiteness. This raises a question of identity that Harris continues to examine: Who has the power to represent self?
In the U.S. especially, Black music is a crucial foundation to American popular music. But as in the UK, it finds its origins in community, folk traditions, and struggle. The industrial nature of the U.S. allows that struggle to be commercialized and disseminated across the globe, creating a sort of paradox. According to Harris, Black individuals must reconcile “being recognized and loved globally, but understanding that people still despise who you are.”
To conduct his research, Harris mostly engages in fieldwork. He spends a significant amount of time in London, engaging with Black communities and listening to live music. His analysis typically involves both sonic and situational elements.
But the most valuable part of Harris’ fieldwork, perhaps, is the community that he himself finds. “Ethnomusicology has for me been a very transformative experience,” he said. “It has helped me to create new global relationships with people — I consider myself now to have homes in several different places.”
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