Duke Research Blog

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

Category: Faculty (Page 1 of 12)

Oral Histories of the Gulag

Gulag Voices: Oral Histories of Soviet Detention and Exile (2011), edited by Jehanne M. Gheith and Katherine R. Jolluck, brings interviews with Gulag survivors to English-speaking audiences. In an interview with Gheith, she reflected on how she began her research on the Soviet forced labor camps called Gulags, ethical complications and different kinds of research opportunities for students.

Dr. Jehanne M. Gheith, Associate Professor of Russian Culture at Duke University and Licensed Clinical Social Worker for Duke Hospice

In the early 1990s, Gheith taught a Gulag memoir to Duke students and realized that while students are aware of the Holocaust, their knowledge on Gulags is limited. After the dissolution of the Soviet Union in the 1990’s, it was possible for Gheith to interview Gulag survivors. She and her co-editor, Katherine Jolluck, connected ten years later when Jolluck was a professor at Stanford. Jolluck had published Exile and Identity: Polish Women in the Soviet Union During World War II, a book about Polish women in the Gulag, the two embarked on a collaborative partnership. Taking the interviews  Gheith had conducted, she and  Jolluck added archival sections and reviewed the interviews.

Memoirs and scholarly works differ from collections of interviews. Gheith felt it was important to conduct a project where she and others could hear the stories of survivors. An influential source that she consulted was the The Gulag Archipelago 1981-1956 (1973) by Nobel Literature Prize winner Aleksandr Solzhenitsyn. The Gulag Archipelago covers three volumes of Solzhenitsyn’s personal experience in the Russian Gulags and his critiques on the Stalin regime.

To find interview subjects for the oral project, Gheith contacted the Russian civil rights organization Memorial. She also interviewed people outside of Memorial using what she described as a “snowball sample.” To piece together the fragmented memories of survivors, Gheith listened and transcribed the stories in the order they were remembered with connecting passages of text. Though time can lead to the misrepresentation of facts, Gheith said, “the facts may be wrong, but you can get to emotional truths.” People may incorrectly recall small details due to numerous factors – nevertheless, through Memorial,  Gheith and Jolluck were able to verify key records of camp survivors, showing the years they were in the camps and the kinds of work they did there.

There were ethical complications Gheith had to surmount – participants could be reluctant to speak about their experiences and expressed surprise that audiences were interested in their memories. Some interviewees were fearful of the Gulag re-occurring and needed to be connected to support resources upon being asked about their encounters.

Gheith also needed to be vigilant about the context and history surrounding Gulags. Because Gulag survivors may have been forced to sign false confessions in the labor camps, Gheith had approval from the Institutional Review Board  to secure verbal agreements on tape in lieu of consent forms.

For students conducting interviews, Gheith suggested reading an oral history, communicating with experts and beginning with a smaller project. Additionally, she had two key points: 1) it is crucial to gain approval from the Institutional Review Board to work with human subjects and 2) if conducting research in a foreign language, the choice between a translator or transcriber should be carefully made, as a translator may shift the relationship dynamic.

In the future, Gheith will be connecting her clinical work to Russian literature and culture. She believes that for students interested in medicine, the arts and humanities have a significant connection to scientific research. Storytelling is also a key part of law and policy, and as students begin to conduct studies in these fields, they are likely to find that the ability to weave a narrative is an indispensable skill. Gheith said she would be happy to talk about the connections between story and medicine with any interested students.

By Ameya Sanyal

Who Gets Sick and Why?

During his presentation as part of the Chautauqua lecture series, Duke sociologist Dr. Tyson Brown explained his research exploring the ways racial inequalities affect a person’s health later in life. His project mainly looks at the Baby Boomer generation, Americans born between 1946 and 1964.

With incredible increases in life expectancy, from 47 years in 1900 to 79 today, elderly people are beginning to form a larger percentage of the population. However among black people, the average life expectancy is three and a half years shorter.

“Many of you probably do not think that three and half years is a lot,” Brown said. “But imagine how much less time that is with your family and loved ones. In the end, I think all of us agree we want those extra three and a half years.”

Not only does the black population in America have shorter lives on average but they also tend to have sicker lives with higher blood pressures, greater chances of stroke, and higher probability of diabetes. In total, the number of deaths that would be prevented if African-American people had the same life expectancy as white people is 880,000 over a nine-year span. Now, the question Brown has challenged himself with is “Why does this discrepancy occur?”

Brown said he first concluded that health habits and behaviors do not create this life expectancy gap because white and black people have similar rates of smoking, drinking, and illegal drug use. He then decided to explore socioeconomic status. He discovered that as education increases, mortality decreases. And as income increases, self-rated health increases. He said that for every dollar a white person makes, a black person makes 59 cents.

This inequality in income points to the possible cause for the racial inequality in health, he said.  Additionally, in terms of wealth instead of income, a black person has 6 cents compared to the white person’s dollar. Possibly even more concerning than this inconsistency is the fact that it has gotten worse, not better, over time. Before the 2006 recession, blacks had 10-12 cents of wealth for every white person’s dollar.

Brown believes that this financial stress forms one of many stressors in black lives including chronic stressors, everyday discrimination, traumatic events, and neighborhood disorder which affect their health.

Over time, these stressors create something called physiological dysregulation, otherwise known as wear and tear, through repeated activation of  the stress response, he said. Recognition of the prevalence of these stressors in black lives has lead to Brown’s next focus on the extent of the effect of stressors on health. For his data, he uses the Health and Retirement Study and self-rated health (proven to predict mortality better than physician evaluations). For his methods, he employs structural equation modeling. Racial inequalities in socioeconomic resources, stressors and biomarkers of physiological dysregulation collectively explain 87% of the health gap with any number of causes capable of filling the remaining percentage.

Brown said his next steps include using longitudinal and macro-level data on structural inequality to understand how social inequalities “get under the skin” over a person’s lifetime. He suggests that the next steps for society, organizations, and the government to decrease this racial discrepancy rest in changing economic policy, increasing wages, guaranteeing work, and reducing residential segregation.

Post by Lydia Goff

Cheating Time to Watch Liquids do the Slow Dance

Colorful spheres simulating liquid molecules shift around inside a cube shape

The team’s new algorithm is able to simulate molecular configurations of supercooled liquids below the glass transition. The properties of these configurations are helping to solve a 70-year paradox about the entropy of glasses. Credit: Misaki Ozawa and Andrea Ninarello, Université de Montpellier.

If you could put on a pair of swimming goggles, shrink yourself down like a character from The Magic School Bus and take a deep dive inside a liquid, you would see a crowd of molecules all partying like it’s 1999.

All this frenetic wiggling makes it easy for molecules to rearrange themselves and for the liquid as a whole to change shape. But for supercooled liquids — liquids like honey that are cooled below their freezing point without crystallizing – the lower temperature slows down the dancing like Etta James’ “At Last.” Lower the temperature enough, and the slow-down can be so dramatic that it takes centuries or even millennia for the molecules to rearrange and the liquid to move.

Scientists can’t study processes that last longer than their careers. But Duke chemists and their Simons Foundation collaborators have found a way to cheat time, simulating the slow dance of deeply supercooled liquids. Along the way, they have found new physical properties of “aged” supercooled liquids and glasses.

A droplet rises above a surface of water

Credit: Ruben Alexander via Flickr.

To understand just how slow deeply supercooled liquids move, consider the world’s longest-running experiment, the University of Queensland’s Pitch Drop Experiment. A single drop of pitch forms every eight to thirteen years — and this pitch is moving faster than deeply supercooled liquids.

“Experimentally there is a limit to what you can observe, because even if you managed to do it over your entire career, that is still a maximum of 50 years,” said Patrick Charbonneau, an associate professor of chemistry and physics at Duke. “For many people that was considered a hard glass ceiling, beyond which you couldn’t study the behavior of supercooled liquids.”

Charbonneau, who is an expert on numerical simulations, said that using computers to simulate the behavior of supercooled liquids has even steeper time limitations. He estimates that, given the current rate of computer advancement, it would take 50 to 100 years before computers would be powerful enough for simulations to exceed experimental capabilities – and even then the simulations would take months.

To break this glass ceiling, the Charbonneau group collaborated with Ludovic Berthier and his team, who were developing an algorithm to bypass these time constraints. Rather than taking months or years to simulate how each molecule in a supercooled liquids jiggles around until the molecules rearrange, the algorithm picks individual molecules to swap places with each other, creating new molecular configurations.

This allows the team to explore new configurations that could take millennia to form naturally. These “deeply supercooled liquids and ultra-aged glasses” liquids are at a lower energy, and more stable, than any observed before.

“We were cheating time in the sense that we didn’t have to follow the dynamics of the system,” Charbonneau said. “We were able to simulate deeply supercooled liquids well beyond is possible in experiments, and it opened up a lot of possibilities.”

Two columns of blue and red spheres represent simulations of vapor-deposited glasses.

Glasses that are grown one layer at a time have a much different structure than bulk glasses. The team used their new algorithm to study how molecules in these glasses rearrange, and found that at low temperatures (right), only the molecules at the surface are mobile. The results may be used to design better types of glass for drug delivery or protective coatings. Credit: Elijah Flenner.

Last summer, the team used this technique to discover a new phase transition in low-temperature glasses. They recently published two additional studies, one of which sheds light on the “Kauzmann paradox,” a 70-year question about the entropy of supercooled liquids below the glass transition. The second explores the formation of vapor-deposited glasses, which have applications in drug delivery and protective coatings.

“Nature has only one way to equilibrate, by just following the molecular dynamics,” said Sho Yaida, a postdoctoral fellow in Charbonneau’s lab. “But the great thing about numerical simulations is you can tweak the algorithm to accelerate your experiment.”

Configurational entropy measurements in extremely supercooled liquids that break the glass ceiling.” Ludovic Berthier, Patrick Charbonneau, Daniele Coslovich, Andrea Ninarello, Misaki Ozawa and Sho Yaida. PNAS, Oct. 24, 2017. DOI: 10.1073/pnas.1706860114

The origin of ultrastability in vapor-deposited glasses.” Ludovic Berthier, Patrick Charbonneau, Elijah Flenner and Francesco Zamponi. PRL, Nov. 1, 2017. DOI: 10.1103/PhysRevLett.119.188002

Post by Kara Manke

Designing Drugs Aimed at a Different Part of Life’s Code

Individual RNA molecules fluoresce inside a breast cancer cell.

Individual RNA molecules fluoresce inside a breast cancer cell. Credit: Sunjong Kwon, Oregon Health & Science University, via Flickr.

Most drugs work by tinkering with the behavior of proteins. Like meddlesome coworkers, these molecules are designed to latch onto their target proteins and keep them from doing what they need to do.

If a protein is responsible for speeding up a reaction, the drug helps slow the reaction down. If a protein serves as a gatekeeper to a cell, regulating what gets in and what stays out, a drug changes how many molecules it lets through.

But proteins aren’t the only doers and shakers in our bodies. Scientists are finding that strings of RNA — known primarily for their role in shuttling genetic information from nucleus-bound DNA to the cell’s protein-manufacturing machinery — can also play a major role in regulating disease.

A portrait of Amanda Hargrove

Amanda Hargrove is an assistant professor of chemistry at Duke University.

“There has been what some people are calling an RNA revolution,” said Amanda Hargrove, assistant professor of chemistry at Duke. “In some diseases, non-coding RNAs, or RNAs that don’t turn into protein, seem to be the best predictors of disease, and even to be driving the disease.”

Hargrove and her team at Duke are working to design new types of drugs that target RNA rather than proteins. RNA-targeted drug molecules have the potential help treat diseases like prostate cancer and HIV, but finding them is no easy task. Most drugs have been designed to interfere with proteins, and just don’t have the same effects on RNA.

Part of the problem is that proteins and RNA have many fundamental differences, Hargrove said. While proteins are made of strings of twenty amino acids that can twist into myriad different shapes, RNA is made of strings of only four bases — adenine, guanine, cytosine and uracil.

“People have been screening drugs for different kinds of RNA for quite a while, and historically have not had a lot of success,” Hargrove said. “This begged the question, since RNA has such chemically different properties than proteins, is there something different about the small molecules that we need in order to target RNA?”

To find out, graduate student Brittany Morgan and research associate Jordan Forte combed the scientific literature to identify 104 small molecules that are known interact with specific types of RNA. They then analyzed 20 different properties of these molecules, and compared their properties to those of collections of drug molecules known to interact with proteins.

The team found significant differences in shape, atomic composition, and charge between the RNA-active molecules and the protein-active molecules. They plan to use the results to compile a collection of molecules, called a library, that are chosen to better “speak the language” of the RNA-active molecules. They hope this collection of molecules will be more likely to interact with RNA in therapeutically beneficial ways.

“We found that there are differences between the RNA-targeted molecules and the protein-targeted drugs, and some of them are pretty striking,” Hargrove said. “What that means is that we could start to enrich our screening libraries with these types of molecules, and make these types of molecules, to have better luck at targeting RNA.”

Discovery of Key Physicochemical, Structural, and Spatial Properties of RNA-Targeted Bioactive Ligands.” Brittany S. Morgan, Jordan E. Forte, Rebecca N. Culver, Yuqi Zhang and Amanda Hargrove. Angewandte Chemie, Sept. 18, 2017. DOI: 10.1002/anie.201707641

Kara J. Manke, PhDPost by Kara Manke

Lab-Made Protein Chomps Co-Factor Like a Big Ol' Gator

A protein is illustrated to look like an alligator mouth

The synthetic protein clamps down on the porphyrin like the jaws of an alligator. Credit: Nicholas Polizzi.

Proteins have the power to turbo-charge biochemical reactions inside the body.

Without the help of types of proteins called enzymes, the reaction that builds DNA could take over 130,000 years to complete. Enzymes cut that time down to just a few milliseconds.

To rev up chemical reactions, many proteins team up with smaller molecules or metals called cofactors. Chemists would like to design proteins that bind to non-biological cofactors in order to speed up chemical reactions not found in nature. But first, they have to figure out how to create man-made proteins that attach to new cofactors in exactly the right way, and that is no easy feat.

A team of chemists at Duke and UC San Francisco is the first to solve this protein design puzzle. The team created a synthetic protein that tightly binds a non-biological catalyst, a type of molecule called porphyrin that is capable of stealing electrons from other molecules when it absorbs light.

“To be able to combine man-made catalysts with proteins would be really big in the chemistry field because then you could combine the power of an enzyme with that of a reaction that isn’t found in nature,” said former Duke graduate student Nicholas Polizzi, who is now a postdoctoral researcher in William DeGrado’s lab at UCSF.

“We were able to figure out the design criteria necessary to place that porphyrin in a protein to within a very high accuracy,” Polizzi said. “That was a really big stepping stone to be able to design new protein-cofactor combinations not seen in nature.”

Proteins are made of chains of hundreds or thousands of smaller amino acids that twist and loop into complex 3-D shapes that can interlock with other molecules like pieces of a jigsaw puzzle. To catalyze chemical reactions, protein-cofactor combinations hold two or more molecules in precisely-shaped pockets that keep the molecules in just the right positions, and provide the right environment, for a chemical reaction to occur.

An illustration of a protein jigsaw puzzle

Chemists at Duke and UCSF designed a synthetic protein that tightly binds a non-biological molecule. Credit: Nicholas Polizzi.

Millions of years of evolution have created proteins that fold into the shapes that tightly grip specific cofactors and provide the perfect environments to catalyze chemical reactions.

For over 25 years, chemists have used what they know about protein folding to design synthetic amino acid sequences that twist up into useful shapes. But so far, they have been unable to design a protein that binds a non-biological cofactor with the precision necessary to power complex new chemical reactions.

Polizzi said this may be because these designs focused primarily on the “binding site” where cofactors and reacting molecules fit into the protein, while ignoring the rest of the structure. “What I did differently is that I considered essentially the entire interior of protein as the binding site for the porphyrin, as opposed to just a few amino acids that touch the porphyrin,” Polizzi said.

To understand how this works, you can think of the protein as the mouth of an alligator, said Michael Therien, William R. Kenan Jr. Professor of Chemistry at Duke. The protein latches onto a cofactor in the same way that an alligator uses its front teeth to chomp down on dinner. But for the front teeth to get a strong grip, the jaw and back teeth also have to be designed correctly.

“The new concept here is that the non-binding region of the protein is held in a shape that allows the binding region to work,” Therien said.

“We called the protein ‘gator’ in the lab,” Polizzi said.

The jaws of the gator protein actually clamp down so hard on the porphyrin cofactor that the whole structure is too rigid to catalyze a reaction, Polizzi said. But with a few tweaks to loosen up the structure, he thinks he can get it to work.

“In this reaction, often times you need a little bit of wiggle room in the protein for it to move. And there was no wiggle room in our protein, everything fit too perfectly,” Polizzi said.

CITATION: “De novo design of a hyperstable non-natural protein-ligand complex with sub-A accuracy.” Nicholas F. Polizzi, Yibing Wu, Thomas Lemmin, Alison M. Maxwell, Shao-Qing Zhang, Jeff Rawson, David N. Beratan, Michael J. Therien and William F. DeGrado. Nature Chemistry, Aug. 21, 2017. DOI: 10.1038/nchem.2846

Kara J. Manke, PhDPost by Kara Manke

Energy Program on Chopping Block, But New Data Suggest It Works

Duke research yields new data about energy efficiency program slated for elimination

Do energy efficiency “audits” really benefit companies over time? An interdisciplinary team of Duke researchers (economist Gale Boyd, statistician Jerome “Jerry” Reiter, and doctoral student Nicole Dalzell) have been tackling this question as it applies to a long-running Department of Energy (DOE) effort that is slated for elimination under President Trump’s proposed budget.

Evaluating a long-running energy efficiency effort

Since 1976, the DOE’s Industrial Assessments Centers (IAC) program has aimed to help small- and medium-sized manufacturers to become more energy-efficient by providing free energy “audits” from universities across the country. (Currently, 28 universities take part, including North Carolina State University.)

Gale Boyd

Gale Boyd is a Duke Economist

The Duke researchers’ project, supported by an Energy Research Seed Fund grant, has yielded a statistically sound new technique for matching publicly available IAC data with confidential plant information collected in the U.S. Census of Manufacturing (CMF).

The team has created a groundbreaking linked database that will be available in the Federal Statistical Research Data Center network for use by other researchers. Currently the database links IAC data from 2007 and confidential plant data from the 2012 CMF, but it can be expanded to include additional years.

The team’s analysis of this linked data indicate that companies participating in the DOE’s IAC program do become more efficient and improve in efficiency ranking over time when compared to peer companies in the same industry. Additional analysis could reveal the characteristics of companies that benefit most and the interventions that are most effective.

Applications for government, industry, utilities, researchers

This data could be used to inform the DOE’s IAC program, if the program is not eliminated.

But the data have other potential applications, too, says Boyd.

Individual companies who took part in the DOE program could discover the relative yields of their own energy efficiency measures: savings over time as well as how their efficiency ranking among peers has shifted.

Researchers, states, and utilities could use the data to identify manufacturing sectors and types of businesses that benefit most from information about energy efficiency measures, the specific measures connected with savings, and non-energy benefits of energy efficiency, e.g. on productivity.

Meanwhile, the probabilistic matching techniques developed as part of the project could help researchers in a range of fields—from public health to education—to build a better understanding of populations by linking data sets in statistically sound ways.

An interdisciplinary team leveraging Duke talent and resources

Boyd—a Duke economist who previously spent two decades doing applied policy evaluation at Argonne National Laboratory—has been using Census data to study energy efficiency and productivity for more than fifteen years. Boyd has co-appointments in Duke’s Social Science Research Institute and Department of Economics. He now directs the Triangle Research Data Center (TRDC), a partnership between the U.S. Census Bureau and Duke University in cooperation with the University of North Carolina and Research Triangle Institute.

The TRDC (located in Gross Hall for Interdisciplinary Innovation) is one of more than 30 locations in the country where researchers can access the confidential micro-data collected by the Federal Statistical System.

Jerry Reiter is a Duke statistician.

Jerry Reiter is a professor in Duke’s Department of Statistical Science, associate director of the Information Initiative at Duke (iiD), and a Duke alumnus (B.S’92). Reiter was dissertation supervisor for Nicole Dalzell, who completed her Ph.D. at Duke this spring and will be an assistant teaching professor in the Department of Mathematics and Statistics at Wake Forest University in the fall.

Boyd reports, “The opportunity to work in an interdisciplinary team with Jerry (one of the nation’s leading researchers on imputation and synthetic data) and Nicole (one of Duke’s bright new minds in this field) has opened my eyes a bit about how cavalier some researchers are with respect to uncertainty when we link datasets. Statisticians’ expertise in these areas can help the rest of us do better research, making it as sound and defensible as possible.”

What’s next for the project

The collaboration was made by possible by the Duke University Energy Initiative’s Energy Research Seed Fund, which supports new interdisciplinary research teams to secure preliminary results that can help secure external funding. The grant was co-funded by the Pratt School of Engineering and Information Initiative at Duke (iiD).

Given the potential uses of the team’s results by the private sector (particularly by electric utilities), other funding possibilities are likely to emerge.

Boyd, Reiter, and Dalzell have submitted an article to the journal Energy Policy and are discussing future research application of this data with colleagues in the field of energy efficiency and policy. Their working paper is available as part of the Environmental and Energy Economics Working Paper Series organized by the Energy Initiative and the Nicholas Institute for Environmental Policy Solutions.

Energy Efficiency Graphic

For more information, contact Gale Boyd: gale.boyd@duke.edu.

Guest Post from Braden Welborn, Duke University Energy Initiative

3D Virus Cam Catches Germs Red-Handed

A 3D plot of a virus wiggling around

The Duke team used their 3D virus cam to spy on this small lentivirus as it danced through a salt water solution.

Before germs like viruses can make you sick, they first have to make a landing on one of your cells — Mars Rover style — and then punch their way inside.

A team of physical chemists at Duke is building a microscope so powerful that it can spot these minuscule germs in the act of infection.

The team has created a new 3D “virus cam” that can spy on tiny viral germs as they wriggle around in real time. In a video caught by the microscope, you can watch as a lentivirus bounces and jitters through an area a little wider that a human hair.

Next, they hope to develop this technique into a multi-functional “magic camera” that will let them see not only the dancing viruses, but also the much larger cell membranes they are trying breech.

“Really what we are trying to investigate is the very first contacts of the virus with the cell surface — how it calls receptors, and how it sheds its envelope,” said group leader Kevin Welsher, assistant professor of chemistry at Duke. “We want to watch that process in real time, and to do that, we need to be able to lock on to the virus right from the first moment.”

A 3D plot spells out the name "Duke"

To test out the microscope, the team attached a fluorescent bead to a motion controller and tracked its movements as it spelled out a familiar name.

This isn’t the first microscope that can track real-time, 3D motions of individual particles. In fact, as a postdoctoral researcher at Princeton, Welsher built an earlier model and used it to track a bright fluorescent bead as it gets stuck in the membrane of a cell.

But the new virus cam, built by Duke postdoc Shangguo Hou, can track particles that are faster-moving and dimmer compared to earlier microscopes. “We were trying to overcome a speed limit, and we were trying to do so with the fewest number of photons collected possible,” Welsher said.

The ability to spot dimmer particles is particularly important when tracking viruses, Welsher said. These small bundles of proteins and DNA don’t naturally give off any light, so to see them under a microscope, researchers first have to stick something fluorescent on them. But many bright fluorescent particles, such as quantum dots, are pretty big compared to the size of most viruses. Attaching one is kind of like sticking a baseball onto a basketball – there is a good chance it might affect how the virus moves and interacts with cells.

The new microscope can detect the fainter light given off by much smaller fluorescent proteins – which, if the virus is a basketball, are approximately the size of a pea. Fluorescent proteins can also be inserted to the viral genome, which allows them to be incorporated into the virus as it is being assembled.

“That was the big move for us,” Welsher said, “We didn’t need to use a quantum dot, we didn’t need to use an artificial fluorescent bead. As long as the fluorescent protein was somewhere in the virus, we could spot it.” To create their viral video, Welsher’s team enlisted Duke’s Viral Vector Core to insert a yellow fluorescent protein into their lentivirus.

Now that the virus-tracking microscope is up-and-running, the team is busy building a laser scanning microscope that will also be able to map cell surfaces nearby. “So if we know where the particle is, we can also image around it and reconstruct where the particle is going,” Welsher said. “We hope to adapt this to capturing viral infection in real time.”

Robust real-time 3D single-particle tracking using a dynamically moving laser spot,” Shangguo Hou, Xiaoqi Lang and Kevin Welsher. Optics Letters, June 15, 2017. DOI: 10.1364/OL.42.002390

Kara J. Manke, PhDPost by Kara Manke

Cooking Up “Frustrated” Magnets in Search of Superconductivity

Sara Haravifard

A simplified version of Sara Haravifard’s recipe for new superconductors, by the National High Magnetic Field Laboratory

Duke physics professor Sara Haravifard is mixing, cooking, squishing and freezing “frustrated” magnetic crystals in search of the origins of superconductivity.

Superconductivity refers to the ability of electrons to travel endlessly through certain materials, called superconductors, without adding any energy — think of a car that can drive forever with no gas or electricity. And just the way gas-less, charge-less cars would make travel vastly cheaper, superconductivity has the potential to revolutionize electronics and energy industry.

But superconductors are extremely rare, and are usually only superconductive at extremely cold temperatures — too cold for any but a few highly specialized applications. A few “high-temperature” superconductors have been discovered, but scientists are still flummoxed at why and how these superconductors exist.

Haravifard hopes that her magnet experiments will reveal the origins of high-temperature superconductivity so that researchers can design and build new materials with this amazing property. In the process, her team may also discover materials that are useful in quantum computing, or even entirely new states of matter.

Learn more about their journey on this fascinating infographic by The National High Magnetic Field Laboratory.

Infographic describing magnetic crystal research

Infographic courtesy of the National High Magnetic Field Laboratory

Kara J. Manke, PhD

Post by Kara Manke

Trapping Light to Enhance Material Properties

Professor Mikkelsen is the Nortel Networks Assistant Professor of Electrical and Computer Engineering and Assistant Professor of Physics at Duke University.

A version of this article appeared in Pratt’s 2017 DukEngineer magazine.

Professor Maiken H. Mikkelsen uses optics to tailor the properties of materials, making them stronger and lighter than anything found in nature. This distinguished researcher also teaches my ECE 340: Optics and Photonics course, giving me a wonderful opportunity to ask about her research and experience at the Photonics Asia conference held in China in October 2016.

Below is an edited transcript of our interview.

Q: What sparked your interest in optics and photonics?
I was really excited about doing hands-on research where you could actually probe nanoscale and quantum phenomena from optical experiments. I started out looking into condensed matter and quantum information science and currently observe delicately designed nanostructures. Optics is, to some extent, a tool to modify the properties of materials.

Q: What does your lab do and how do students contribute?
During the last few years, my students and I have been structuring materials on the nanoscale to modify the local electromagnetic environment, which makes these materials behave in new ways. Students play a key role in all aspects of the research, from nanofabrication to performing optical experiments and presenting the results to the scientific community at conferences all over the world. The lab uses tiny metal structures to concentrate the incoming electromagnetic field of light to very small volumes — a research area known as plasmonics. Placing other materials in the near field of this modified environment causes the electrons to behave completely differently.

Platform based on metal nanostructures that allows the lab to dramatically enhance the radiative properties of emitters and other materials.

By controlling how these electrons behave and modifying the geometry of the material, we can gain a deeper understanding of the light-matter interactions. Combining these techniques with our optical experiments shows modifications to material properties that are much stronger than has been seen before. It’s been very exciting!

Q: And this research is what you presented at the Photonics Asia conference?
Yes. With this knowledge, we can enhance the properties of materials significantly, which in the future could lead to ultra-fast and much better LEDs, more efficient photodetectors, or more efficient solar cells and sensors. In Beijing, China, I gave an overview of this research at the leading meeting for the photonics and optics industries in Asia, as well as several other conferences and universities. It was very fulfilling to see how the research I do in a dark lab actually gets noticed around the world. It is always deeply inspiring to learn about recent research breakthroughs from other research groups.

Q: What is the main purpose of trying to find these improved materials?
I am motivated by furthering our fundamental understanding, such as how do light and matter interact when we get to really small scales and how this interaction can be leveraged to achieve useful properties. I believe you often achieve the biggest technological breakthroughs when you’re not trying to solve one particular problem, but creating new materials that could lay the groundwork for a wide range of new technologies. For example, semiconductor materials, with a set of properties that are found naturally, are the cornerstone of most modern technologies. But if you imagine that you now have an entirely new set of building blocks with tailored properties instead, we could revolutionize a lot of different technologies down the road.

The Mikkelsen Research Group. Back row, left to right: Qixin Shen, Andrew Traverso, Maiken Mikkelsen, Guoce Yang, Jon Stewart, Andrew Boyce. Front row, left to right: Wade Wilson, Daniela Cruz, Jiani Huang, Tamra Nebabu.

By improving or completely changing the fabrication technique of these light-matter interactions, new properties begin to emerge. Generally, there’s always a big desire to have something that’s lighter, smaller, more efficient and more flexible. One of the applications we’re targeting with this research is ultrafast LEDs. While future devices might not use this exact approach, the underlying physics will be crucial.

About a year ago, Facebook contacted me and was interested in utilizing our research for omnidirectional detectors that could be ultrafast and detect signals from a large range of incidence angles. This has led to a fruitful collaboration and is one example of how fundamental research can have applications in a wide range of areas — some that you may not even have imagined when you started!

 

Q: What would be your advice to young researchers still trying to decide a career path for themselves or those interested in optics and photonics?
What really helped me was starting to do undergraduate research. I listened to talks by different faculty, asked them to do undergraduate research, and worked on a volunteer basis in their labs. I think that’s really a great way to see if you’re interested in research — use the amazing opportunities both at Duke and around the country. Doing research requires a lot of patience, but I think no two days are the same; there’s always a lot of creativity involved while troubleshooting new problems. After all, if it was easy or if we knew how to do it, it would have already been done. But it hasn’t, so we have to figure it out — I think that is a lot of fun. Doing internships in optics and photonics companies is also another option to learn more about research and development in the industry. Get as many experiences as possible and give things a chance!

Professor Mikkelsen is best known for the first demonstration of nondestructive readout of a single electron spin, ultrafast manipulation of a single spin using all-optical techniques, and extreme radiative decay engineering using nanoantennas.

Mikkelsen has received numerous accolades, including the Cottrell Scholar Award, the Maria Goeppert Mayer Award, and a “triple crown” of Young Investigator Awards from the Air Force, Army and Navy. Her work has been published in the journals Science, Nature Photonics, and Nature Physics, to name a few. Professor Mikkelsen enjoys hiking, gardening, playing tennis, and traveling in her free time.

Learn more at mikkelsen.pratt.duke.edu.

Written by Anika Radiya-Dixit

Students Share Research Journeys at Bass Connections Showcase

From the highlands of north central Peru to high schools in North Carolina, student researchers in Duke’s Bass Connections program are gathering data in all sorts of unique places.

As the school year winds down, they packed into Duke’s Scharf Hall last week to hear one another’s stories.

Students and faculty gathered in Scharf Hall to learn about each other’s research at this year’s Bass Connections showcase. Photo by Jared Lazarus/Duke Photography.

The Bass Connections program brings together interdisciplinary teams of undergraduates, graduate students and professors to tackle big questions in research. This year’s showcase, which featured poster presentations and five “lightning talks,” was the first to include teams spanning all five of the program’s diverse themes: Brain and Society; Information, Society and Culture; Global Health; Education and Human Development; and Energy.

“The students wanted an opportunity to learn from one another about what they had been working on across all the different themes over the course of the year,” said Lori Bennear, associate professor of environmental economics and policy at the Nicholas School, during the opening remarks.

Students seized the chance, eagerly perusing peers’ posters and gathering for standing-room-only viewings of other team’s talks.

The different investigations took students from rural areas of Peru, where teams interviewed local residents to better understand the transmission of deadly diseases like malaria and leishmaniasis, to the North Carolina Museum of Art, where mathematicians and engineers worked side-by-side with artists to restore paintings.

Machine learning algorithms created by the Energy Data Analytics Lab can pick out buildings from a satellite image and estimate their energy consumption. Image courtesy Hoël Wiesner.

Students in the Energy Data Analytics Lab didn’t have to look much farther than their smart phones for the data they needed to better understand energy use.

“Here you can see a satellite image, very similar to one you can find on Google maps,” said Eric Peshkin, a junior mathematics major, as he showed an aerial photo of an urban area featuring buildings and a highway. “The question is how can this be useful to us as researchers?”

With the help of new machine-learning algorithms, images like these could soon give researchers oodles of valuable information about energy consumption, Peshkin said.

“For example, what if we could pick out buildings and estimate their energy usage on a per-building level?” said Hoël Wiesner, a second year master’s student at the Nicholas School. “There is not really a good data set for this out there because utilities that do have this information tend to keep it private for commercial reasons.”

The lab has had success developing algorithms that can estimate the size and location of solar panels from aerial photos. Peshkin and Wiesner described how they are now creating new algorithms that can first identify the size and locations of buildings in satellite imagery, and then estimate their energy usage. These tools could provide a quick and easy way to evaluate the total energy needs in any neighborhood, town or city in the U.S. or around the world.

“It’s not just that we can take one city, say Norfolk, Virginia, and estimate the buildings there. If you give us Reno, Tuscaloosa, Las Vegas, Pheonix — my hometown — you can absolutely get the per-building energy estimations,” Peshkin said. “And what that means is that policy makers will be more informed, NGOs will have the ability to best service their community, and more efficient, more accurate energy policy can be implemented.”

Some students’ research took them to the sidelines of local sports fields. Joost Op’t Eynde, a master’s student in biomedical engineering, described how he and his colleagues on a Brain and Society team are working with high school and youth football leagues to sort out what exactly happens to the brain during a high-impact sports game.

While a particularly nasty hit to the head might cause clear symptoms that can be diagnosed as a concussion, the accumulation of lesser impacts over the course of a game or season may also affect the brain. Eynde and his team are developing a set of tools to monitor both these impacts and their effects.

A standing-room only crowd listened to a team present on their work “Tackling Concussions.” Photo by Jared Lazarus/Duke Photography.

“We talk about inputs and outputs — what happens, and what are the results,” Eynde said. “For the inputs, we want to actually see when somebody gets hit, how they get hit, what kinds of things they experience, and what is going on in the head. And the output is we want to look at a way to assess objectively.”

The tools include surveys to estimate how often a player is impacted, an in-ear accelerometer called the DASHR that measures the intensity of jostles to the head, and tests of players’ performance on eye-tracking tasks.

“Right now we are looking on the scale of a season, maybe two seasons,” Eynde said. “What we would like to do in the future is actually follow some of these students throughout their career and get the full data for four years or however long they are involved in the program, and find out more of the long-term effects of what they experience.”

Kara J. Manke, PhD

Post by Kara Manke

Page 1 of 12

Powered by WordPress & Theme by Anders Norén