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Duke Research - March 2011

boron-hydrogen fusion

March 31, 2011

Overturned scientific explanation may be good news for nuclear fusion

Flat out wrong.

That’s what a team of Duke researchers has discovered, much to its surprise, about a long-accepted explanation of how nuclei collide to produce charged particles for electricity – a process receiving intense interest lately from scientists, entrepreneurs and policy makers in the wake of Japan’s nuclear crisis.

Plasma physicists have been trying for 25 years to create electricity from the fusion of boron and hydrogen atoms.

The new study says their efforts have been based on a misunderstanding of the underlying physics – although the error could end up actually helping those looking to fusion energy as an alternative energy source.

Researchers have been developing reactors to slam hydrogen at high speeds into boron-11, a collision that yields high-energy helium nuclei, or alpha particles. Those alphas then spiral through a tunnel of electromagnetic coils, transforming them into a flow of electrons, or electricity.

“Obviously, a detailed understanding of the energy and location of every outgoing alpha particle is crucial to the development of this reactor,” says Duke nuclear physicist Henry Weller, a co-author of the new study.

Weller and his colleagues took a fresh look at the hydrogen-boron reaction at the Triangle Universities Nuclear Laboratory (TUNL) on Duke’s campus. They expected to confirm the accepted wisdom that a collision of one hydrogen particle and one boron-11 particle produces a single high-energy alpha particle --  which produces electricity well – and two lower energy alphas, which are less useful for generating electricity.

inside fusion reactorInstead, the team found the collision yields two high-energy alphas, which shoot off at an angle of 155 degrees, along with one lower-energy alpha. The existence of this second high-energy alpha could mean these kinds of fusion systems are able to produce much more electricity than expected, says Duke nuclear physicist and study co-author Mohammad Ahmed. The results appear online in Physics Letters B.

The unexpected finding appears to confirm a long-forgotten observation from physicists at Cavendish Laboratory in Cambridge, England. In 1936, they made crude, but apparently correct, estimates of the two higher-energy alphas.

Their results were “buried in history” until now, Ahmed says.

Now, 75 years later, the new insight makes the boron-fusion reaction even more interesting as a possible alternative to the nuclear fission process used in reactors in Japan and other parts of the world. A reactor based on this process could produce electricity without radioactive wastes. It also would not produce the carbon dioxide and other gases emitted by coal-powered plants.

Nuclear fusion still faces formidable challenges, one of the greatest being that hydrogen and boron only begin to fuse at temperatures close to 1 billion degrees Kelvin (nearly 2 billion degrees Fahrenheit). But building this type of reactor is realistic, says Weller, whose team is continuing to study the process at TUNL.


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Tags: physics


March 29, 2011

Goodall visits her data at Duke

It’s hard to imagine Jane Goodall being envious of anyone, let alone the undergraduate and graduate students in Duke’s evolutionary anthropology program.

But as the legendary primatologist visited the university’s new research center that houses her 50-year data-collection on chimpanzees, it became evident that the scientist longed to “sit down and dive right in” to the data.

Seeing it again is “bittersweet,” Goodall said during a press conference on March 28 at Duke.  “I love to analyze data” and rifling through the files “makes me homesick for that,” she said, noting how much easier the analysis has become since the data is now digitized.

For the past 20 years, primatologist Anne Pusey has worked with colleagues and students to scan and make electronic notes of Goodall’s long-hand narratives, audio transcriptions and grids of abbreviated data called "check-sheets." Pusey rescued the data from Goodall’s home in Dar Es Salaam, Africa in the 1970s.

The data “was just sitting in open shelves,” being chewed by mice, and it was at risk of being destroyed, Pusey said. With Goodall’s consent, Pusey brought the stacks of chimpanzee narratives to the United States and finally to Duke when she joined the faculty as the chair of the university’s evolutionary anthropology program last year.

Goodall arrived in what is now Gombe National Park in Tanzania in 1960. Since then she, along with field staff and students, have taken 18,000 days of meticulous notes on one of humans’ closest relatives in the wild. The data fills 22 filing cabinets with daily narratives on the feeding, mating and social behaviors of chimpanzees.

The data provides detailed descriptions of the first evidence of tool-use in animals other than humans. The observations document chimpanzee warfare and the need for males to earn social dominance, behaviors many scientists thought Goodall should not publish.

They thought the observations would be an excuse to say that human war and violence is inevitable, Goodall said. “I do think violence is part of our tendency,” part of human inheritance from chimps’ and humans’ common ancestor, she said. But the data also show true altruism, the willingness to help outsiders.

Seeing altruism in chimps and believing that characteristic is also inherited gives Goodall hope, she said, as do human intelligence, the resilience of nature and the indomitable human spirit. Her hope is for individuals, especially the younger generations, to work every day to help chimpanzees, other animals, each other and the planet.Jane Goodall with Sohmee Kim and Dorian Hayes

After meeting Goodall and hearing about her activist program called Roots & Shoots, Dorian Hayes, 9, and Sohmee Kim, 10, were already planning play dates with friends to learn more about what they could do.

They listed examples like trying to get their parents to drive less and asking their teachers if they could start a Roots & Shoots program at their school.

“Jane Goodall is funny. She’s cool. I read about her before this, and now she’s my hero,” Kim said, adding that she was certain she would one day study several breeds of wild cats to see how their environments influenced their behavior.

Hayes said she too wanted to study animals but was not sure what type or in what regions of the world.

Aaron Sandel’s inspiration from Goodall’s visit came from seeing her “academic side,” he said. Sandel, a research associate in Pusey’s lab, along with other students and researchers, gave Goodall a tour of the research center that houses her data.

“You could see the scientist in her. You could see her first love was the chimpanzees and the data,” said Sandel, who graduated from Duke in 2010.

He added that Goodall seemed impressed with the available computer technology, and she was excited to show her colleagues in Tanzania what was being done with the data.

“Seeing that definitely highlighted for her the promise of her research to inspire global and high-tech analysis,” he said. She even seemed “a bit jealous,” because she understands that the data keep coming in, making the “research possibilities almost endless,” Sandel said. “It was a privilege to share and generate research ideas with her.”


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Tags: behavior/psychology, field research, lecture

Jane Goodall and young Flint

March 28, 2011

Why We Study Chimpanzees

“Why do people do something that benefits someone else but is detrimental to themselves?” Ian Gilby asked during a panel discussion, March 24. “Chimps are one of the few animals that do this really frequently,” he said.

The panelists, Gilby, Anne Pusey, Deus Mjungu and Lilian Pintea, discussed the history of chimpanzee research and conservation at Gombe National Park in Tanzania.

The lecture was the second of the “Conservation Toolkit” series, put on as part of Duke/UNC Roots & Shoots and the Department of Evolutionary Anthropology’s second-annual Primate Palooza event. This year, Primate Palooza honors the 50th anniversary of Dr. Jane Goodall’s chimpanzee research at Gombe. Dr. Goodall is speaking at Duke on March 28.

Goodall began studying chimpanzees at Gombe in 1960. She didn’t have a college  degree, but she had a talent for observation and a passion for animals. She took precise notes, referring to the chimps by the names she gave them.

“[Dr. Goodall] was interested in everything,” Pusey said. “People knew almost nothing about how chimpanzees behaved in the wild ... It became clear that they’re very much like us in certain ways.”

Dr. Goodall’s observations, plus notes taken by other researchers these past 50 years, have found a new home at Duke. Over 400,000 pages of records are being digitized in order to preserve the information and make it more accessible. The information lives in a sophisticated database where every piece of data is linked to every other piece of data. “It really is incredible for answering questions that you can’t answer without decades of data,” Pintea said.

A question from the audience steered the conversation toward conservation efforts. “When you are there, you feel like you are in the middle of the most remote place,” Pintea said of Gombe. However, outside the park development encroaches from all sides. “Overnight, researchers find themselves being not just researchers, but conservationists.”

“I think that the research coming out of Gombe helps to put chimpanzees on the map and helps all of us in other places where you don’t get insights into their lives. It helps the general population get more interested,” Pintea said. “It’s really important that, if a chimpanzee dies in Africa, people realize that they’ve lost something.”

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Tags: animals, behavior/psychology, environment/sustainability

Jane Goodall in the forest at Gombe

March 28, 2011

Putting Values on Resources

“Unless you know that [a resource] is going to be in your family for a very long time, you usually don’t manage it sustainably,” evolutionary anthropology professor Thomas Struhsaker said during a panel discussion, March 25.

 "People are people and they will try to exploit things, especially if they're common ground, as much as they can. You take what you can, because you never know what’s going to happen tomorrow."

The discussion, “Strategies for Protecting Tropical Forests,” also included Dr. Jane Carter Ingram of the Wildlife Conservation Society, NC State professor Erin Sills and James Madison University professor Josh Linder.

The session was the third of the “Conservation Toolkit” series in our week-long Primate Palooza event, leading up to Jane Goodall's Monday appearance. The panel was sponsored by Duke/UNC Roots & Shoots and the Department of Evolutionary Anthropology.

Tropical forests can be found on five continents. They offset humanity’s carbon emissions and are home to countless species, many of them endangered. But they also contain coveted raw materials. Why conserve tropical forests? Are they worth more than the timber, palm oil and agricultural land they contain?

Struhsaker objected to the question. “It’s anthropogenic. It’s like asking us, what is the value of your home to you? If you ask from the perspective of the animals, it's no question.”

“Do we get rid of something, do we kill it just because it doesn’t have an economic value?” Linder asked. “At the end of the day, hopefully it’s valuable for some reason. Otherwise it’s going to be gone.”

Sills, an economist by training, pointed out that an object’s value always depends on how abundant or how scarce it is. “If you’re sitting in the middle of the forest, it’s not scarce. From a global perspective, it’s very different,” she said. This disparity may explain why local communities tend not to view conservation as a priority.

Unfortunately, there is no single solution. The success of different policies depends on local politics, ethics, education and standard of living. But “when you have all the factors coming together, you can have a tremendously positive story,” Sills said.

Costa Rica is one such example. “A big part of their national economy is based on ecotourism, and you need an intact natural environment in order to do that,” Ingram said. Costa Rica’s efforts to protect its natural resources have helped increase tourism and reduce poverty in the country.

Is Costa Rica’s progress a sign of things to come? Perhaps, but “I don’t think we can ever sit back on our laurels and think that we’ve solved the problem,” Ingram said. So for now, they’re taking it one thing at a time.

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Tags: animals, biology, climate/global change, environment/sustainability, field research

Glass of beer and can

March 22, 2011

A Seminar on the Science of Beer

They may have been Puritans, but beer was their choice of beverage to bring on a voyage to America.

Beer was safer than water because it had been boiled, not for safety, but to bring out bitterness, flavor and aroma. It’s one of a chain of processes that convert raw ingredients into the world’s most widely-consumed alcoholic beverage.

It turns out that beer requires a surprising amount of science.

Former Duke grad student Dr. Tim Wadkins, a brewer and winemaker, spoke about this science in a March 17 talk sponsored by the Department of Molecular Genetics and Microbiology, the Department of Cell Biology and the Center for the Study of Aging and Human Development.

“Brewers like to tell you that they make beer,” Wadkins said. “But they’re really making food for yeast  to make beer.”

Wadkins described four ingredients that every brewer needs. Germinating cereal grains, also known as malt, produce enzymes that convert starches into sugars. Heating prevents the grains from germinating further.

Hops are the female flower clusters of the hop plant (Humulus lupulus). They act as a natural preservative and add bitterness, flavor and aroma to a beer when boiled. “They’re all flowers,” Wadkins said. “Some can be as different from one another as the smell of a rose from the smell of a tulip.”

Yeast are living microscopic organisms that munch sugar from the malt to create carbon dioxide (“fizziness”) and ethyl alcohol (“dizziness”).  The type of yeast dictates many components of a beer’s taste. So-called “wild” yeasts can yield flavors as variant as pineapple, butterscotch, bacon and Band-Aids. Some flavors are produced deliberately, but others (eau de Band-Aid?) emerge as an unintended byproduct of the process, perhaps because the beer is too old or wasn’t packaged properly.

Water is easily overlooked, but critical to the beer-making process. “If your water doesn’t taste good at your brewery, then your beer is never going to taste good, no matter what you do to it,” Wadkins said. 

After thorough malting, milling, mashing, lautering, boiling and fermenting, the beer is ready to go. But there’s one last thing. Isohumulone compounds contribute to beer’s bitter taste, but they also react with light to produce MBT, a compound you may recognize if you’ve ever gotten on a skunk’s bad side. Fortunately for us, brewers usually package their beer in cans or very dark bottles to prevent this process from occurring.

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Tags: biology, chemistry, lecture, science communication & education

texas tower

March 21, 2011

To be or not to be, a psychopath

Less than one percent of people are psychopaths. Yet, psychopaths commit more than 30 percent of all violent crimes. “That’s a giant problem,” said Walter Sinnott-Armstrong, a philosopher at Duke.

The problem of psychopaths’ violent crimes compares in size to drug abuse. But, unlike the National Institute on Drug Abuse, the National Institute of Psychopaths doesn’t exist. The National Institute of Mental Health does exist and is working to solve mental health problems. But it spends more resources on diseases such as schizophrenia, which have lesser societal impact than psychopathy, Sinnott-Armstrong said.

“There’s really not enough research and resources spent on psychopaths. We don’t really understand them. But solving the problem could help them and protect us,” he said, explaining the interview and brain-scan data scientists have collected from prisons in New Mexico during a talk on Feb. 24.

In a second talk, part of Brain Awareness Week, on March 17, Sinnott-Armstrong described the 1966 case of Charles Whitman, the Texas Tower Sniper. Whitman murdered his wife and mother at their home and then climbed the Texas Tower, where he killed fourteen people and injured dozens more in just over ninety minutes. A police officer finally shot and killed Whitman, ending his spree.

While the crime may sound psychotic, Whitman wasn’t a psychopath. He left a note questioning whether he had any reason for “the actions I have recently performed.” He said he loved his wife, but did not “want to leave her to suffer alone” in the world. He also asked that after his death, doctors examine his body to determine if a physical cause led to his mental anguish and eventual killing spree.

When doctors performed the autopsy, they discovered a small tumor in Whitman’s brain. Tumors do not cause psychopathy, in most cases, and psychopaths do not show remorse or acknowledge their actions are wrong, like Charles Whitman, Sinnott-Armstrong said. He wasn’t a psychopath, he said, but whether he can be held morally or legally responsible for his actions, on account of his brain tumor, is less black and white.

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Tags: behavior/psychology, lecture

molecular tug of war

March 4, 2011

Molecular tug-of-war could lead to new materials

Tug-of-war isn’t just for play. In the chemistry world, the game could identify a Saran-wrap-like material that instantly heals microscopic tears in its own structure.

Duke scientists are testing this idea using atomic forceps to tug on individual molecules. They’ve already discovered that a slight pull can pop open rare, triangle-shaped molecular structures in milliseconds.

The usual way to open these molecules is to heat them at high temperatures – overnight, said chemist Stephen Craig, who described his research at a colloquium on March 3. With the molecular tug-of-war, Craig foresees a microscopic world where scientists could almost instantly move molecules and atoms to create new materials and even new chemistry.

Craig and his colleagues recently explored how molecule chains, called polymers, can snap back to structures smaller than their original forms. The team also trapped a molecule in the middle of the reaction that made it shrink. Typically that halfway point, called a “transition state,” lasts for less than one millionth of a millionth of a second, but Craig’s team succeeded in “catching lightning in a bottle,” which may be useful in understanding the electronic properties of the transition state.

To quantify the tug-of-war at the molecular level requires an atomic force microscope. Craig sees the tool like a diving board. When a particularly heavy person or tough molecule is on the end, the board bends way down. Measuring the bend of the microscope’s board, the team can put a number to the force or strength of the molecule being tugged.

The microscope can pull harder and harder on the chain until it breaks, which shows the polymers that can endure the “heaviest diver” or most force. His team can also use the tool to watch if specific molecules change their shapes, such as opening and closing their triangle structures, as the polymer starts to break apart.

By seeing this new chemistry as it happens, Craig and other scientists could learn how to move atoms and molecules where they need them. The manipulation provides scientists with another way to create new materials for applications from longer-lasting coatings on artificial hips to plastic wrapping that never gets holes.

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Tags: chemistry, lecture, physics, research


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