The Catastrophic Origins of Our Moon

This still from a model shows a planet-sized object just after collision with earth. The colors indicate temperature. (Photo: Robin Canup)

This still from a model shows Earth just after collision with a planet-sized object. The colors indicate temperature. (Photo: Robin Canup)

By Erin Weeks

About 65 million years ago, an asteroid the size of Manhattan collided with the Earth, resulting in the extinction of 75% of the planet’s species, including the dinosaurs.

Now imagine an impact eight orders of magnitude more powerful — that’s the shot most scientists believe formed the moon.

One of the leading researchers of the giant impact theory of the moon’s origin is Robin Canup, associate vice president of the Planetary Science Directorate at the Southwest Research Institute. Canup was elected to the National Academy of Sciences in 2012, and she’s also a graduate of Duke University — where she returned yesterday to give the fifth Hertha Sponer Lecture, named for the physicist and first woman awarded a full professorship in science at Duke.

According to the giant impact hypothesis, another planet-sized object crashed into Earth shortly after its formation 4.5 billion years ago. The catastrophic impact sent an eruption of dust and vaporized rock into space, which coalesced into a disk of material rotating around Earth’s smoldering remains (see a very cool video of one model here).  Over time, that wreckage accreted into larger and larger “planetesimals,” eventually forming our moon.

Physics professor Horst Meyer took this photo of Robin Canup, who was his student as an undergraduate,

Robin Canup (Photo: Horst Meyer, who taught Canup as an undergrad at Duke)

Scientists favor this scenario, Canup said, because it answers a number of questions about our planet’s unusual lunar companion.

For instance, our moon has a depleted iron core, with 10% instead of the usual 30% iron composition. Canup’s models have shown the earth may have sucked up the molten core of the colliding object, leaving the dust cloud from which the moon originated with very little iron in it.

Another mystery is the identical isotopic signature of the moon and the earth’s mantle, which could be explained if the two original bodies mixed, forming a hybrid isotopic composition from the collision.

Canup’s models of the moon’s formation help us understand the evolution of just one (albeit important) cosmic configuration in our galaxy. As for the rest out there, she says scientists are just beginning to plump the depths of how they came to be. Already, the models show “they’re even crazier than the theoreticians imagined.”

Finding Order in Insect and Orc Swarms

Ouellette's model of insect swarming

Ouellette’s model of insect swarming

By Olivia Zhu

Dr. Nicholas Ouellette looks for the organization in disorder.

Ouellette, associate professor in the mechanical engineering department at Yale University, studies collective motion in animal systems. On February 17, he presented his models of swarming of Chironomus riparius, the non-biting midge, as part of Duke’s Physics Colloquium. Ouellette ultimately hopes to pin down fundamental laws of biology through his physics research.

In the lab, Ouellette has found that Chironomus insects swarm in a columnar, teardrop shape in the center of their container. They only live in their flying state for two to three days, during which they mate, lay eggs and die. During this period, swarming affords them protection from predators and the opportunity to mate.

Ouellette and his lab have devised various methods of modeling the insects’ swarming. They found that the insect density remains constant, and that the “scattering,” or collisions of insects, mirrors that of an ideal gas over long periods of time. Interestingly, the graph of individual insect speed follows a Maxwell-Boltzmann distribution, even though the lab did not track the usual factors that create such a distribution, like temperature.

The most pressing question Ouellette would like to answer is which factors create a swarm—he has determined that close insect-insect repulsion contributes to swarming, but distant insect-insect attraction does not. To pursue this question, Ouellette is testing how many insects it takes to make a swarm.

Wildebeest stampede modeled in The Lion King

Wildebeest stampede modeled in The Lion King

Other animals that exhibit collective motion are mackerel, wildebeests and starlings. Some familiar examples of collective motion modeling are visible as the Orcs storm the castle in Lord of the Rings and as the wildebeests charge the canyon in The Lion King.

Learn to Fly a Drone in Three Minutes

By Erin Weeks

Missy Cummings has accomplished a lot of difficult things in her life — she was one of the Navy’s first female pilots, after all — but being a guest on The Colbert Report, she said, was hard.

Cummings told the story of her journey from Naval lieutenant to media drone expert last week at the Visualization Friday Forum seminar series in a talk (video archived here) titled “Designing a System for Navigating Small Drones in Tight Spaces.”

Missy Cummings joined Duke as an associate professor of mechanical engineering and materials science last semester

Missy Cummings joined Duke as an associate professor of mechanical engineering and materials science last semester.

Last semester, Cummings moved her renowned Humans and Automation Lab from MIT to Duke University. She’s wasted no time immersing herself in the new university and volunteered for the semester’s first seminar to introduce herself and her lab’s latest work to Duke’s visualization community.

Cummings’ research over recent years has centered on the development of a smartphone interface through which, she said, anyone can learn to pilot a one-pound drone in three minutes. The technology could be a boon to the U.S. Army, which now issues smartphones to its personnel and mostly relies on cumbersome, gas-powered drones.

The lab tested the technology by asking volunteers to maneuver a drone through an obstacle course both in the field — where they learned wind and cold temperatures are not a drone’s friend — and in simulated environments.

One of the things they discovered in both cases was that individuals who performed well in a spatial reasoning test were more likely to complete the obstacle course. Moreover, these performances tended to be gendered, with men scoring higher than women in spatial reasoning. Interestingly, Cummings noted, other studies have shown women tend to perform better piloting drones in long-term, “boring” scenarios with little action.

Cummings is interested in teasing out the reasons for these results, which could have significant implications for the U.S. Army or companies one day interested in hiring drone pilots.

As Stephen Colbert confirmed, you may be able to fly a drone with three minutes’ training, but that doesn’t mean you can fly it well.

Cummings talks to a full house at the Visualization Friday Forum on January 24.

Cummings talks to a full house at the Visualization Friday Forum on January 24.

New Course Offers Lessons from Lasering Priceless Art

Duke graduate student Tana Villafana and chief conservator at the NC Museum of Art William Brown stand over The Crucifixion (inset). (Photo: Martin Fischer)

Duke graduate student Tana Villafana and chief conservator at the NC Museum of Art William Brown stand over The Crucifixion (inset). (Photo: Martin Fischer)

By Erin Weeks

A group of chemists at Duke University has gained recognition in recent years for shooting lasers at medieval artwork — technology that allows a harmless peek at the many layers and materials in a painting and offers insight into long gone eras and artists. Now, Duke students will have the chance to learn from this pioneering work at the intersection of chemistry and art history in a new course on the science of color.

The course coincides with the publication of the first scientific measurements from the laser work, reported Jan. 20 in the Proceedings of the National Academy of Sciences.

“The images we have now are enormously better than a year ago,” said Warren S. Warren, head of the lab performing the imaging and the James B. Duke professor of chemistry. He and fellow Duke authors, grad student Tana Villafana and associate research professor Martin Fischer, have not only demonstrated the technology works — they’ve shown it works at an incredible level of detail, telling the difference, for example, between nearly identical pigments.

But lasering The Crucifixion by Puccio Cappano was just the start, as the team envisions countless more cultural applications of the technology. Given enough funding and manpower, they could visualize ancient scrolls of text too fragile to unroll, reveal the bright colors that once adorned Greek statues, learn the secrets of China’s terracotta warriors, and even detect the beginnings of pigment degradation in aging artwork.

There are talented people in art conservation, Warren said, whose work could benefit from more advanced technology, and there are talented people at the cutting-edge of laser science looking for meaningful ways to apply their inventions. For the past several years, Warren’s lab has brought these people together.

Now, he hopes to accomplish something similar with students at Duke. Warren, Fischer, and another chemistry instructor, Adele DeCruz, are teaming up to teach “The Molecular, Physical, and Artistic Bases of Color” in the second half of spring semester.

The class will visit the Nasher Museum of Art, the North Carolina Museum of Art in Raleigh, and possibly even the National Gallery of Art in Washington, D.C, to learn first-hand from art conservators and working artists. Students can expect to learn about how humans have used and made pigments over the millennia; how color works at a molecular level; and the basics of how human vision, microscopes, cameras, and lasers all see or image color.

Students can register for the half course, CHM 590, until the add/drop deadline for classes on January 22. “Students should not be scared off by the course number,” Warren said. “The prerequisite is one college-level science course, and the intent is to make both the science and artistic components accessible to a broad audience.”

Funding for the research was provided by National Science Foundation grant CHE-1309017.

CITATION: “Femtosecond pump-probe microscopy generates virtual cross-sections in historic artwork.” Tana E. Villafana, William P. Brown, et al. Proceedings of the National Academy of Sciences, Jan. 20, 2014. Doi: 10.1071/pnas.1317230111

Pretty pictures show lemurs responding to changing climate

Guest Post by Sheena Faherty, Biology Graduate Student 

Madagascar’s much-adored and fuzzy lemurs might be “sweated out” of habitats by warming environments under global climate change. Or will they?

A team of researchers at the Duke Lemur Center is employing high-tech heat cameras used in  fire fighting, sports medicine and cancer diagnostics to take “glowing” rainbow pictures of lemurs and their forest surroundings. The results look similar to a child’s coloring project gone rogue.

A mother and baby Coquerel's Sifaka at the Lemur Center in thermograph and visible light. (Leslie Digby)

A mother and baby Coquerel’s Sifaka at the Lemur Center in thermograph and visible light. (Leslie Digby)

This technology, known as infrared thermography, is a camera that allows researchers to detect surface temperatures of lemurs and their hang-outs in the forest—at different depths and heights—and on varying surfaces such as the ground, leaves, and tree trunks.

Combining these data with records of where an animal prefers to spend time, the researchers can begin to determine what temperatures make lemurs most happy.

Leslie Digby, an associate professor in the Department of Evolutionary Anthropology, and her students want to see  how the lemurs are changing their behavior to warm-up on cool days, and cool-down on warm days without having to shiver or sweat.

This sounds rather like a lizard basking on a rock during a sunny day to warm his cold-blooded body up, but lemurs aren’t cold-blooded. They shouldn’t have to do this.

It turns out that even though lemurs are warm-blooded, they can conserve precious energy by channeling their inner Buddha — using sunning behaviors, just like lizards, to fine-tune core body temperatures.

Digby’s team is trying to understand why some species have seemingly restricted territories, even without obvious geographical barriers like mountain ranges or rivers. They suspect temperature plays a part.

“We know that primate species ranges have been very different in the past, so understanding how flexible these animals are, or [are] not, to temperatures can help us understand these larger scale impacts [of changing climate]”, says Digby.

Figuring out how animals respond to alterations in their environment, like rising temperatures, can help scientists anticipate species’ survival in the face of globally changing climates. And knowing which areas of the forest are preferred by lemurs, could help direct conservation efforts, like reforesting parts that have been cut down, or preserving those areas that have not.

Changing temperatures will undoubtedly have major impacts on lemur home ranges in the future, potentially altering them until the animals  are forced into an area outside their thermal limits. By gearing her research toward understanding the thermal tolerances of lemurs, Digby is doing her part to protect the vulnerable lemurs.

A ringtailed lemur striking the classic belly-warming Buddha pose in one of the natural enclosures at Duke Lemur Center. (David Haring)

A ringtailed lemur striking the classic belly-warming Buddha pose in one of the natural enclosures at Duke Lemur Center. (David Haring)

Teaching Young Scientists the Elements of Design

by Erin Weeks

Ten visiting undergraduate researchers spent the summer sharpening their science communication skills at Duke. They came from around the country to chemistry and engineering labs to participate in a National Science Foundation program called Chemistry and Applications of Smart Molecules and Materials and to learn the principles of ‘molecule-to-material’ research.

While the students spent most of their days in the lab, they were also tasked with creating a visual representation to explain some aspect of their summer research—once at the beginning of the summer, and once again at the end, after feedback and instruction on the basics of good visual design. The process was designed to help the students understand their research, their roles as scientists, and the importance of science communication.

“You want to catch peoples’ eye, but you want to be fairly simple and easy to interpret,” said chemistry professor and department chair Stephen Craig. Craig and project co-leader, associate chemistry professor Kathy Franz, discussed their project at a visualization seminar series last week (Nov 1).

As for the visual don’ts, Craig advised the students to skip abstract art and avoid anything flashy or over the top. In addition to the images, the students practiced explaining their research in strictly timed three-minute talks.

“We wanted them to give that elevator pitch, that three-minute pitch,” said Franz, so that the students would be able to “communicate to their peers what their project for the summer was going to be.”

Duke professor Jane Richardson first visualized protein as ribbon-like (Courtesy Wikimedia)

Duke professor Jane Richardson first visualized protein as ribbon-like (Courtesy Wikimedia)

When Franz was a student, she was never trained how to make her research graphics clear and intelligible. But as a chemist, she knew the significance of effective visuals. Take, for example, the structure of proteins, which were first visualized as ribbon-like in 1980 by Duke biochemist Jane Richardson. These days, Franz said, she and generations of biology students only picture protein as a ribbon.

“The way people represent scientific results changes the way we imagine it,” Franz said.