Measuring depths, scaling heights

Graduate student Leigh Ann Kesler is pursuing her two great interests: fusion science and rock climbing. One day she finds herself scrambling up bare rock faces to view grand vistas of mountains and valleys carved by glaciers, the next she is in the laboratory, exploring minute changes in the depth of materials being eroded by fusion forces.

Kesler studies at MIT’s Plasma Science and Fusion Center (PSFC), and dates her interest in fusion back to an 11th-grade persuasive writing assignment. Inspired in part by her father’s interest in the potential of nuclear energy, she decided to investigate fusion. Searching for the topic at the library in her Fisher, Illinois, high school, she found just one 1970s-vintage book on the topic, but its description of a magnetic fusion device called a tokamak was compelling enough to hook her for good.

As an undergrad at the University of Illinois, Kesler studied nuclear, plasma, and radiological engineering, learning the basics about how plasmas affect materials from one of her mentors, Professor David Ruzic. Working in his laboratory on projects related to semiconductor manufacturing as well as fusion, she gained a reputation for expertise with plasma diagnostics. Graduate students several years her senior soon began to seek her help with their projects.

“I don’t know if I was an expert,” she says, laughing. “But I had several advantages. I had small hands. I could reach inside of the bottom of the chamber [of the experiment]. I’d been there long enough that they knew I wasn’t going to break things.”

Understanding fusion devices

Now at MIT, she is continuing her research in materials science and fusion research under the guidance of Professor Dennis Whyte, head of the Nuclear Science and Engineering Department and director of the PSFC, and Assistant Professor Zach Hartwig. As she did in Illinois, she works in a lab that utilizes small-scale plasma devices for ex situ observation of plasma surface interactions.  

Her main focus is erosion of materials inside fusion devices, where strong magnetic fields keep the hot plasma fuel confined and away from the walls of the vacuum chamber where fusion reactions occur. But the plasma can still affect the walls, resulting in surface erosion and other changes.

“It’s very difficult to determine exactly how a particular kind of plasma discharge affects the interior material of the machine,” Kesler says. "We can’t be sure of the amount of erosion occurring at any particular moment. Erosion affects not only the wall materials, but also the plasma itself, which can become contaminated by the eroded materials. If you are eroding or even melting the surfaces you will eventually destroy the divertor, which is designed to remove impurities from the plasma.”

She works mainly on a 2 megavolt electrostatic accelerator called DANTE in the Vault Laboratory for Nuclear Science, which is part of the Center for Science and Technology with Accelerators and Radiation (CSTAR). The lab is a shielded, underground facility that allows her to work safely with a deuterium ion beam. She also uses CSTAR's Cambridge Laboratory for Accelerator Surface Science, giving her the versatility of working with two ion sources.

Kesler is searching for a way to measure, on a shot-by-shot basis, what changes are happening on the interior surface of the tokamak in order to gain a better understanding of how different plasma conditions affect surfaces. To this end, she will use the accelerator to create “depth markers” to help measure changes in the metallic surfaces. She is working with tungsten, a metal that will likely be used for the divertors of future tokamaks.

“Accelerators can be used to implant stuff into the surface of a material," she says. A layer of a material, like boron, put close to the surface can be used as a reference point.

"If the location of this layer changes after interacting with the plasma that means the amount of tungsten on the surface has changed," she says. "Either something has been added or something has been taken away.”

Kesler is still fine-tuning what that reference point will be, the best material to use, how to create the depth marker, and how to use the accelerators to see how the plasma has affected the surface. Her technique should be applicable to any material and will be relevant to tokamaks around the world, allowing researchers to diagnose the effect of each plasma shot as it happens.

“Addicted to hiking”

While the lab keeps her busy, Kesler has been able to indulge her love of hiking and rock climbing, not only in the mountains of New England, but in places as far away as Machu Picchu, the Faroe Islands, and Mount Vesuvius. She started rock climbing during a summer internship in Los Alamos, New Mexico, where after work she would explore the area crags with friends.

“It turned into the best summer of my life, and I was addicted to hiking and climbing after that.”

At MIT she got involved with more aspects of the sport when she started going on trips with the MIT Outing Club (MITOC). Soon she was a hiking and climbing leader, and is currently on the board of directors.

“MITOC has been an amazing part of my grad school experience, allowing me to make friends with shared interests and to let me escape the confines of the city on the weekends. As a country girl, I get sick of the city, so New Hampshire has been my second home while I'm here.”

On a mountain she can study the surface of a rock that will provide her next foothold instead of the interior surface of a tokamak. She can breathe the thin air of high altitudes before returning to her underground laboratory. She was excited about her recent hike with five friends from MITOC to Gannett Peak, Wyoming’s highest point, where she was able to watch the total eclipse on Aug. 21.

“We hiked for two days to high camp, took one day to summit, then one day to retreat. I had bruised my heel six weeks earlier in a climbing accident, so I was out of shape, but the trip was still amazing. Viewing the totality of the eclipse was mind-blowing. The 360-degree sunset/sunrise and the reality of the sun disappearing from view was something I cannot describe. It is an experience of a lifetime.”

Now at the beginning of her fifth year, Kesler is still researching and writing, but starting to consider her options after graduation. “An international postdoctoral position in materials development would be great. But I’m not so much interested in where I go as in doing interesting work,” she says.

Ideally that work will be situated not far from a mountain, she says. “There are always more rocks to climb.”

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President Reif writes to support preservation of DACA

Writing in The Boston Globe, MIT President L. Rafael Reif has called on U.S. President Donald Trump and Congress to preserve the federal Deferred Action for Childhood Arrivals (DACA) program, saying that a proposed repeal “would run counter to our national interest [and] strikes me as a violation of deep American principles.”

Created in 2012, DACA pertains to young people brought to the U.S. without documentation when they were under age 16, a group sometimes known as Dreamers. Under DACA, if these individuals identify themselves to the government and meet strict criteria — such as having earned a high school diploma, being enrolled in higher education or engaged in the military, and having committed no serious crime — they receive a temporary reprieve from the threat of deportation.

Noting that Trump faces potential legal action by a number of states seeking to end the program, Reif noted in an op-ed published in Friday’s newspaper: “As we see at MIT and at campuses across the country, the threat of DACA repeal is subjecting these young people to brutal uncertainty. Now, because of decisions made for them when they were children, they fear losing the opportunities they earned, the communities they think of as home, and the nation they love.”

In the op-ed, Reif calls upon Congress to pass legislation protecting the DREAMers, and asks Trump to allow Congress time to act. He notes that polls have found that the vast majority of Americans oppose repeal of DACA, and that congressional Republicans and Democrats have proposed workable legislative solutions. He writes that a repeal would run counter to the national interest by removing productive workers, while costing the federal government tens of billions of dollars in lost tax revenues and the direct costs of deportation.

“And because Dreamers are, by definition, products of the U.S. education system, driving them out would be throwing away a tremendous national investment,” Reif notes. “We should treat these educated, English-speaking strivers not as a burden, but as a resource.”

“The plight of the Dreamers presents a profound question of fairness,” Reif adds. “Often starting from harsh personal circumstances, these young people have done what any American family might dream of for their child: study hard, aim high, and earn a degree or a place in college or the military, on the road to a productive career. They are undocumented through no fault of their own. And when offered an opportunity to come out of the shadows, they did — because they trusted that our government would not punish them for it.”

In his op-ed, Reif notes that he himself is an immigrant — a native of Venezuela who came to the U.S. as a graduate student in 1974, and has since become a U.S. citizen.

“I have the particular patriotism of an immigrant, rooted in deep gratitude and appreciation for a country founded on a dream of fairness,” he writes in closing. “I urge President Trump and the Congress to find a sound, stable legislative path to keep that promise of fairness for the Dreamers, too.”

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New way to test antibiotics could lead to better drugs

MIT and Harvard University researchers have engineered E. coli cells that can be used to study how bacteria at an infection site respond to antibiotic treatment, allowing scientists to learn more about how existing antibiotics work and potentially help them to develop new drugs.

In the new study, which appears in the Aug. 31 issue of Cell Host and Microbe, the researchers found evidence that some existing hypotheses about how bacteria respond to antibiotics are not correct.

“Our study shows that using engineered organisms can give you a window into infection sites and expand our understanding of what antibiotics are actually doing. This work indicates that some of our assumptions may be wrong,” says James Collins, the Termeer Professor of Medical Engineering and Science in MIT’s Institute for Medical Engineering and Science (IMES) and Department of Biological Engineering and the senior author of the study.

The paper’s lead author is Laura Certain, a clinical fellow at Harvard’s Wyss Institute for Biologically Inspired Engineering.

Engineering bacteria

Much of the research in Collins’ lab focuses on trying to understand how antibiotics work, in hopes of designing more effective drugs. For the new study, Collins wanted to apply synthetic biology — the construction of novel genetic circuits in living cells — to design bacteria that could be used to study antibiotics and infection.

Most studies of how antibiotics work are done with bacterial cells grown in a lab dish. However, Collins and Certain suspected that these drugs’ effects could be different in living animals because that environment, including available nutrients and other conditions, is very different from a lab dish.

To allow them to study antibiotics under more realistic conditions, the researchers engineered a strain of E. coli bacteria that expresses a genetic “toggle switch” that flips only under certain conditions. Such switches can be incorporated into bacteria to allow them to record events such as exposure to a chemical.

In this case, the researchers designed the bacteria to reveal whether they were dividing or not, allowing them to explore how antibiotics affect cells in either state. Previous studies done in bacteria grown in a lab dish have found that most antibiotics work better on cells that are dividing, while non-replicating cells are much harder to kill.

The researchers delivered the bacteria to mice along with a small orthopedic implant, to mimic the infections that often occur at the sites of medical implants. The mice were then treated with the antibiotic levofloxacin. Before and after treatment, the cells were removed and treated with ATC, a molecule that turns on the toggle switch, but only in cells that are replicating.

Scientists have hypothesized from previous studies that chronic infections usually consist largely of non-dividing bacteria. However, in this study, the researchers found that before antibiotic treatment, about half of the bacteria were still actively dividing.

They also found that levofloxacin appeared to be highly and perhaps even more effective against non-dividing cells, contrary to what has been seen in cells grown in a dish. The researchers noted that the percentage of replicating cells increased after treatment, suggesting that levofloxacin did not kill all of the replicating cells.

Another surprising finding contradicted scientists’ hypothesis that chronic persistent infections consisting of non-dividing bacteria are highly tolerant to antibiotics: They found the infections were still susceptible to antibiotics, when given at large enough doses.

More to learn

Collins says this study demonstrates that there is much more for scientists to learn about how antibiotics work, and suggests that engineered organisms could be useful for further investigating their effects.

“This is going to challenge people to rethink what antibiotics are doing at an infection site,” Collins says. “I think that eventually these synthetic biology tools could also be quite useful in antibiotic development, to see whether the antibiotics are getting to the pathogens of interest, how effective they are, and what they are actually doing at the site.”

He adds that the genetic toggle switch could be easily transferred to other types of bacteria, and could also be designed to test for other features such as how bacteria interact with immune cells at an infection site. This approach could also be used to study biofilms — sticky sheets of bacterial cells that can be very difficult to remove — and other pathogens such as fungi.

The research was funded by the Paul G. Allen Frontiers Group, the Defense Threat Reduction Agency, and the Wyss Institute.

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Neighboring exoplanets may hold water, study finds

Seven Earth-sized exoplanets circle the ultracool dwarf star TRAPPIST-1, just 40 light-years from our own blue planet. Now an international team of scientists at the Geneva Observatory in Switzerland, MIT, and elsewhere, report that the outer planets in this system may still hold significant stores of water. Three of these potential water worlds are also considered within the habitable zone of the star, giving further support to the possibility that these neighboring planets may, in fact, be hospitable to life.

The team’s results, published today in The Astronomical Journal, are based on observations of the TRAPPIST-1 star made by the NASA/ESA Hubble Space Telescope. The researchers trained the telescope on the star to measure its current ultraviolet radiation, and used these measurements to estimate how the star’s energy changed over the course of billions of years. They then modeled how the star’s energy may have affected the water resources on each of the TRAPPIST-1 exoplanets over the last 8 billion years.   

Scientists’ current knowledge of the system suggests that these planets originally formed much farther out from their star, in a cold zone populated with crystals of water ice, which the planets likely captured as they came together, potentially creating tremendous stores of water, both in the planets’ interiors and on their surfaces.

From their observations and modeling, the researchers conclude that, over the past 8 billion years, heat and radiation from the star may have caused the innermost planets to lose more than 20 times the amount of water in all of Earth’s oceans. Meanwhile, they say, the outer planets would have lost much less, suggesting they could still retain some water on their surfaces and in their interiors.

“In terms of habitability, this is a positive step forward to say that hopes are still high,” says study co-author Julien de Wit, a postdoc in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “This concludes that a few of these outer planets could have been able to hold onto some water, if they accumulated enough during their formation. But we need to gather more information and actually see a hint of water, which we haven’t found yet.”

A water vapor break-up

In February of 2016, de Wit and others from the University of Liege in Belgium announced the discovery of the seven Earth-sized planets around TRAPPIST-1. The discovery marked the largest number of Earth-sized planets discovered in a single system.

Since then, de Wit, lead author Vincent Bourrier of the Geneva Observatory,

and an international team of researchers used the Hubble Space Telescope Imaging Spectrograph (STIS) to measure the amount of ultraviolet radiation given off by the TRAPPIST-1 star then received by its planets. If a planet’s atmosphere harbors water vapor, the presence of ultraviolet radiation can act to break up that water vapor, into oxygen and hydrogen — a process that occurs today on Earth. As oxygen is heavier than hydrogen, it sinks towards the surface, while hydrogen rises through the upper atmosphere.

The researchers hoped that by using Hubble’s imaging spectrograph, they might look for signs of hydrogen, particularly around two of the middle planets. The researchers were focused on a very narrow region of the ultraviolet spectrum, called the Lyman-alpha band, which is sensitive to hydrogen. They reasoned that if they picked up traces of hydrogen around either planet, that would suggest the presence of water vapor.

In 2016, the team trained the telescope on the TRAPPIST-1 system over one observing run of five orbits for each planet, totaling eight hours, in which they gathered 4.5 hours of data. Unfortunately, the observations of whether each planet contained hydrogen, and therefore water vapor, were inconclusive.

However, the researchers also obtained measurements of the star’s ultraviolet flux, or the strength of its radiation. They compared these measurements to similar ones made the previous year.

“We see this flux is actually changing, and we can use this change to backtrack and have an understanding of how much energy the star is putting on each planet over the course of the planets’ lives,” de Wit explains.

Oceans lost

Based on previous estimates of the planets’ densities, the scientists assume that the planets likely formed much farther out from their current positions, beyond what is considered the “ice line” — the distance from the star, beyond which space is cold enough for ice crystals to spontaneously form. It’s likely that all seven TRAPPIST-1 planets took shape within this zone, taking up significant volumes of water ice as they formed.

Researchers have also previously observed that the planets’ orbital configurations are such that they likely migrated together, “moving as a pack,” as de Wit describes, eventually taking up their current positions, closer into their star. As they migrated into the star’s warmer zone, the star’s ultraviolet radiation likely started to strip away and evaporate the planets’ water resources.

In their current paper, the scientists used their estimates of the star’s ultraviolet flux over the last 8 billion years to estimate the amount of water the the planets likely lost as they migrated over this period of time, closer in to their star.

The team plugged the estimates of ultraviolet flux into two separate models: an atmospheric model that calculates the amount of water vapor that might be lost given a certain ultraviolet concentration, and a geophysical model that estimates how much water ice and other volatiles, buried deep in a planet’s interior, can be brought back up into the atmosphere via outgassing.

From their modeling, the scientists estimate that the innermost planets lost more than 20 times Earth’s current oceanic water stores over their 8-billion-year journey toward their star, while the outermost planets lost much less, equivalent to around three times the ocean stores on Earth.

“Earth-sized planets can capture hundreds of Earth-oceans’ worth of water when they form, but it’s highly dependent on so many factors, and difficult to say,” de Wit says. “We can say the inner ones probably lost a huge amount of water, and the outer ones way less, allowing them to actually still have some water, if they captured it when they first formed.”

“It depends a lot on their initial water content,” Bourrier adds. “If they formed as ocean planets, even the inner ones would likely still harbor a lot of water. We are still a long way to determining the habitability of these planets, but our results suggest that the outer ones might be the best targets to focus our future observations.”

De Wit and his colleagues are planning another observing run, and will use Hubble to monitor the system more closely, spending more time observing, and trying to look for clouds of hydrogen around each planet as they transit, or cross in front of their star.

“If the planet’s atmosphere holds water vapor, and it is losing hydrogen as it reacts with ultraviolet radiation, it will look a bit like a gigantic comet with a tail, or a sphere that’s 10 times bigger than the planet, filled with atomic hydrogen, that is slowly flowing out of the planet, forming a tail from the stellar wind,” de Wit says. “It’s amazing how quickly our perspective on this [system] has changed. It’s really a steep learning curve that is really exciting.”

This research was supported, in part, by NASA, the Space Science Telescope Institute, the Swiss National Science Foundation, the Simons Foundation, the Belgian National Fund for Scientific Research, and the Gruber Foundation.

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Increasing equity through educational technology

Justin Reich was ready to observe a teacher integrating technology into her lesson plan at a school in rural New Hampshire. Her school had bought the laptops, Reich says. She had reserved them. They were charged. All of the kids were logged in. The power was on in the building. The wireless network was working. The projector bulb was working. The screen was working. But when the teacher went to plug the projector into the wall, the electrical socket fell behind the drywall, foiling her attempted lesson plan. “New technologies have tremendous potential to improve student learning,” Reich says, “but many pieces in a complex system need to be working seamlessly to make this happen.”

Reich, an assistant professor in MIT’s Comparative Media Studies/Writing Program (CMS/W), has remained excited about the possibilities that constantly evolving technologies have brought to the learning process over the last few decades. But while many believe that the free and low-cost learning tools becoming available have huge potential to lift up students from low-income families, he’s found that, in truth, this educational technology still benefits the affluent the most.

“I think people underestimate barriers,” Reich says. “Many educators get into the work because they want to create a more equitable world. But educational settings often end up reproducing social inequalities and social hierarchies.”

Through his work as executive director at the MIT Teaching Systems Lab, which now straddles CMS/W and the Office of Digital Learning, Reich works toward finding educational models that incorporate technology in ways that actually will increase quality of education and equity for students.

“All over the world, people are looking to see a shift in classroom teaching practice to more active, engaged, inquiry-based collaborative learning,” he says. “And the only way that will happen is if we can dramatically increase the quantity and quality of teacher learning that’s available.”

Having started off as a wilderness medicine instructor, Reich comes from a hands-on teaching background. Now, he makes sure he and his projects are constantly engaging with real classroom settings. He co-founded EdTechTeacher, a professional learning consultancy which focuses on finding thoughtful ways to use technology in teaching and learning. He also keeps conversations going with classroom instructors through his Education Week-hosted blog, EdTechResearcher.

Reich has also created learning tools for teachers through two online courses, Launching Innovation in Schools, done in collaboration with Peter Senge of the Sloan School of Management; and Design Thinking for Leading and Learning. Both courses were funded by Microsoft with a $650,000 grant.

In CMS/W, he looks to explore the field of learning science and the role that media plays in expanding human capacity, particularly in a civic sense.

“We investigate the complex technology-rich classrooms of the future and the systems that we need to help educators thrive in those settings,” he says.

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Making data centers more energy efficient

Most modern websites store data in databases, and since database queries are relatively slow, most sites also maintain so-called cache servers, which list the results of common queries for faster access. A data center for a major web service such as Google or Facebook might have as many as 1,000 servers dedicated just to caching.

Cache servers generally use random-access memory (RAM), which is fast but expensive and power-hungry. This week, at the International Conference on Very Large Databases, researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) are presenting a new system for data center caching that instead uses flash memory, the kind of memory used in most smartphones.

Per gigabyte of memory, flash consumes about 5 percent as much energy as RAM and costs about one-tenth as much. It also has about 100 times the storage density, meaning that more data can be crammed into a smaller space. In addition to costing less and consuming less power, a flash caching system could dramatically reduce the number of cache servers required by a data center.

The drawback to flash is that it’s much slower than RAM. “That’s where the disbelief comes in,” says Arvind, the Charles and Jennifer Johnson Professor in Computer Science Engineering and senior author on the conference paper. “People say, ‘Really? You can do this with flash memory?’ Access time in flash is 10,000 times longer than in DRAM [dynamic RAM].”

But slow as it is relative to DRAM, flash access is still much faster than human reactions to new sensory stimuli. Users won’t notice the difference between a request that takes .0002 seconds to process — a typical round-trip travel time over the internet — and one that takes .0004 seconds because it involves a flash query.

Keeping pace

The more important concern is keeping up with the requests flooding the data center. The CSAIL researchers’ system, dubbed BlueCache, does that by using the common computer science technique of “pipelining.” Before a flash-based cache server returns the result of the first query to reach it, it can begin executing the next 10,000 queries. The first query might take 200 microseconds to process, but the responses to the succeeding ones will emerge at .02-microsecond intervals.

Even using pipelining, however, the CSAIL researchers had to deploy some clever engineering tricks to make flash caching competitive with DRAM caching. In tests, they compared BlueCache to what might be called the default implementation of a flash-based cache server, which is simply a data-center database server configured for caching. (Although slow compared to DRAM, flash is much faster than magnetic hard drives, which it has all but replaced in data centers.) BlueCache was 4.2 times as fast as the default implementation.

Joining Arvind on the paper are first author Shuotao Xu and his fellow MIT graduate student in electrical engineering and computer science Sang-Woo Jun; Ming Liu, who was an MIT graduate student when the work was done and is now at Microsoft Research; Sungjin Lee, an assistant professor of computer science and engineering at the Daegu Gyeongbuk Institute of Science and Technology in Korea, who worked on the project as a postdoc in Arvind’s lab; and Jamey Hicks, a freelance software architect and MIT affiliate who runs the software consultancy Accelerated Tech.

The researchers’ first trick is to add a little DRAM to every BlueCache flash cache — a few megabytes per million megabytes of flash. The DRAM stores a table which pairs a database query with the flash-memory address of the corresponding query result. That doesn’t make cache lookups any faster, but it makes the detection of cache misses — the identification of data not yet imported into the cache — much more efficient.

That little bit of DRAM doesn’t compromise the system’s energy savings. Indeed, because of all of its added efficiencies, BlueCache consumes only 4 percent as much power as the default implementation.

Engineered efficiencies

Ordinarily, a cache system has only three operations: reading a value from the cache, writing a new value to the cache, and deleting a value from the cache. Rather than rely on software to execute these operations, as the default implementation does, Xu developed a special-purpose hardware circuit for each of them, increasing speed and lowering power consumption.

Inside a BlueCache server, the flash memory is connected to the central processor by a wire known as a “bus,” which, like any data connection, has a maximum capacity. BlueCache amasses enough queries to exhaust that capacity before sending them to memory, ensuring that the system is always using communication bandwidth as efficiently as possible.

With all these optimizations, BlueCache is able to perform write operations as efficiently as a DRAM-based system. Provided that each of the query results it’s retrieving is at least eight kilobytes, it’s as efficient at read operations, as well. (Because flash memory returns at least eight kilobytes of data for any request, it’s efficiency falls off for really small query results.)

BlueCache, like most data-center caching systems, is a so-called key-value store, or KV store. In this case, the key is the database query and the value is the response.

"The flash-based KV store architecture developed by Arvind and his MIT team resolves many of the issues that limit the ability of today's enterprise systems to harness the full potential of flash,” says Vijay Balakrishnan, director of the Data Center Performance and Ecosystem program at Samsung Semiconductor’s Memory Solutions Lab. “The viability of this type of system extends beyond caching, since many data-intensive applications use a KV-based software stack, which the MIT team has proven can now be eliminated. By integrating programmable chips with flash and rewriting the software stack, they have demonstrated that a fully scalable, performance-enhancing storage technology, like the one described in the paper, can greatly improve upon prevailing architectures.”

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Robotic system monitors specific neurons

Recording electrical signals from inside a neuron in the living brain can reveal a great deal of information about that neuron’s function and how it coordinates with other cells in the brain. However, performing this kind of recording is extremely difficult, so only a handful of neuroscience labs around the world do it.

To make this technique more widely available, MIT engineers have now devised a way to automate the process, using a computer algorithm that analyzes microscope images and guides a robotic arm to the target cell.

This technology could allow more scientists to study single neurons and learn how they interact with other cells to enable cognition, sensory perception, and other brain functions. Researchers could also use it to learn more about how neural circuits are affected by brain disorders.

“Knowing how neurons communicate is fundamental to basic and clinical neuroscience. Our hope is this technology will allow you to look at what’s happening inside a cell, in terms of neural computation, or in a disease state,” says Ed Boyden, an associate professor of biological engineering and brain and cognitive sciences at MIT, and a member of MIT’s Media Lab and McGovern Institute for Brain Research.

Boyden is the senior author of the paper, which appears in the Aug. 30 issue of Neuron. The paper’s lead author is MIT graduate student Ho-Jun Suk.

Precision guidance

For more than 30 years, neuroscientists have been using a technique known as patch clamping to record the electrical activity of cells. This method, which involves bringing a tiny, hollow glass pipette in contact with the cell membrane of a neuron, then opening up a small pore in the membrane, usually takes a graduate student or postdoc several months to learn. Learning to perform this on neurons in the living mammalian brain is even more difficult.

There are two types of patch clamping: a “blind” (not image-guided) method, which is limited because researchers cannot see where the cells are and can only record from whatever cell the pipette encounters first, and an image-guided version that allows a specific cell to be targeted.

Five years ago, Boyden and colleagues at MIT and Georgia Tech, including co-author Craig Forest, devised a way to automate the blind version of patch clamping. They created a computer algorithm that could guide the pipette to a cell based on measurements of a property called electrical impedance — which reflects how difficult it is for electricity to flow out of the pipette. If there are no cells around, electricity flows and impedance is low. When the tip hits a cell, electricity can’t flow as well and impedance goes up.

Once the pipette detects a cell, it can stop moving instantly, preventing it from poking through the membrane. A vacuum pump then applies suction to form a seal with the cell’s membrane. Then, the electrode can break through the membrane to record the cell’s internal electrical activity.

The researchers achieved very high accuracy using this technique, but it still could not be used to target a specific cell. For most studies, neuroscientists have a particular cell type they would like to learn about, Boyden says.

“It might be a cell that is compromised in autism, or is altered in schizophrenia, or a cell that is active when a memory is stored. That’s the cell that you want to know about,” he says. “You don’t want to patch a thousand cells until you find the one that is interesting.”

To enable this kind of precise targeting, the researchers set out to automate image-guided patch clamping. This technique is difficult to perform manually because, although the scientist can see the target neuron and the pipette through a microscope, he or she must compensate for the fact that nearby cells will move as the pipette enters the brain.

“It’s almost like trying to hit a moving target inside the brain, which is a delicate tissue,” Suk says. “For machines it’s easier because they can keep track of where the cell is, they can automatically move the focus of the microscope, and they can automatically move the pipette.”

By combining several imaging processing techniques, the researchers came up with an algorithm that guides the pipette to within about 25 microns of the target cell. At that point, the system begins to rely on a combination of imagery and impedance, which is more accurate at detecting contact between the pipette and the target cell than either signal alone.

The researchers imaged the cells with two-photon microscopy, a commonly used technique that uses a pulsed laser to send infrared light into the brain, lighting up cells that have been engineered to express a fluorescent protein.

Using this automated approach, the researchers were able to successfully target and record from two types of cells — a class of interneurons, which relay messages between other neurons, and a set of excitatory neurons known as pyramidal cells. They achieved a success rate of about 20 percent, which is comparable to the performance of highly trained scientists performing the process manually.

Unraveling circuits

This technology paves the way for in-depth studies of the behavior of specific neurons, which could shed light on both their normal functions and how they go awry in diseases such as Alzheimer’s or schizophrenia. For example, the interneurons that the researchers studied in this paper have been previously linked with Alzheimer’s. In a recent study of mice, led by Li-Huei Tsai, director of MIT’s Picower Institute for Learning and Memory, and conducted in collaboration with Boyden, it was reported that inducing a specific frequency of brain wave oscillation in interneurons in the hippocampus could help to clear amyloid plaques similar to those found in Alzheimer’s patients.

“You really would love to know what’s happening in those cells,” Boyden says. “Are they signaling to specific downstream cells, which then contribute to the therapeutic result? The brain is a circuit, and to understand how a circuit works, you have to be able to monitor the components of the circuit while they are in action.”

This technique could also enable studies of fundamental questions in neuroscience, such as how individual neurons interact with each other as the brain makes a decision or recalls a memory.

Bernardo Sabatini, a professor of neurobiology at Harvard Medical School, says he is interested in adapting this technique to use in his lab, where students spend a great deal of time recording electrical activity from neurons growing in a lab dish.

“It’s silly to have amazingly intelligent students doing tedious tasks that could be done by robots,” says Sabatini, who was not involved in this study. “I would be happy to have robots do more of the experimentation so we can focus on the design and interpretation of the experiments.”

To help other labs adopt the new technology, the researchers plan to put the details of their approach on their web site, autopatcher.org.

Other co-authors include Ingrid van Welie, Suhasa Kodandaramaiah, and Brian Allen. The research was funded by Jeremy and Joyce Wertheimer, the National Institutes of Health (including the NIH Single Cell Initiative and the NIH Director’s Pioneer Award), the HHMI-Simons Faculty Scholars Program, and the New York Stem Cell Foundation-Robertson Award.

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Robot learns to follow orders like Alexa

Despite what you might see in movies, today’s robots are still very limited in what they can do. They can be great for many repetitive tasks, but their inability to understand the nuances of human language makes them mostly useless for more complicated requests.

For example, if you put a specific tool in a toolbox and ask a robot to “pick it up,” it would be completely lost. Picking it up means being able to see and identify objects, understand commands, recognize that the “it” in question is the tool you put down, go back in time to remember the moment when you put down the tool, and distinguish the tool you put down from other ones of similar shapes and sizes.

Recently researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have gotten closer to making this type of request easier: In a new paper, they present an Alexa-like system that allows robots to understand a wide range of commands that require contextual knowledge about objects and their environments. They've dubbed the system “ComText,” for “commands in context.”

The toolbox situation above was among the types of tasks that ComText can handle. If you tell the system that “the tool I put down is my tool,” it adds that fact to its knowledge base. You can then update the robot with more information about other objects and have it execute a range of tasks like picking up different sets of objects based on different commands.

“Where humans understand the world as a collection of objects and people and abstract concepts, machines view it as pixels, point-clouds, and 3-D maps generated from sensors,” says CSAIL postdoc Rohan Paul, one of the lead authors of the paper. “This semantic gap means that, for robots to understand what we want them to do, they need a much richer representation of what we do and say.”

The team tested ComText on Baxter, a two-armed humanoid robot developed for Rethink Robotics by former CSAIL director Rodney Brooks.

The project was co-led by research scientist Andrei Barbu, alongside research scientist Sue Felshin, senior research scientist Boris Katz, and Professor Nicholas Roy. They presented the paper at last week’s International Joint Conference on Artificial Intelligence (IJCAI) in Australia.

How it works

Things like dates, birthdays, and facts are forms of “declarative memory.” There are two kinds of declarative memory: semantic memory, which is based on general facts like the “sky is blue,” and episodic memory, which is based on personal facts, like remembering what happened at a party.

Most approaches to robot learning have focused only on semantic memory, which obviously leaves a big knowledge gap about events or facts that may be relevant context for future actions. ComText, meanwhile, can observe a range of visuals and natural language to glean “episodic memory” about an object’s size, shape, position, type and even if it belongs to somebody. From this knowledge base, it can then reason, infer meaning and respond to commands.

“The main contribution is this idea that robots should have different kinds of memory, just like people,” says Barbu. “We have the first mathematical formulation to address this issue, and we’re exploring how these two types of memory play and work off of each other.”

With ComText, Baxter was successful in executing the right command about 90 percent of the time. In the future, the team hopes to enable robots to understand more complicated information, such as multi-step commands, the intent of actions, and using properties about objects to interact with them more naturally.

For example, if you tell a robot that one box on a table has crackers, and one box has sugar, and then ask the robot to “pick up the snack,” the hope is that the robot could deduce that sugar is a raw material and therefore unlikely to be somebody’s “snack.”

By creating much less constrained interactions, this line of research could enable better communications for a range of robotic systems, from self-driving cars to household helpers.

“This work is a nice step towards building robots that can interact much more naturally with people,” says Luke Zettlemoyer, an associate professor of computer science at the University of Washington who was not involved in the research. “In particular, it will help robots better understand the names that are used to identify objects in the world, and interpret instructions that use those names to better do what users ask.”

The work was funded, in part, by the Toyota Research Institute, the National Science Foundation, the Robotics Collaborative Technology Alliance of the U.S. Army, and the Air Force Research Laboratory.

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New robot rolls with the rules of pedestrian conduct

Just as drivers observe the rules of the road, most pedestrians follow certain social codes when navigating a hallway or a crowded thoroughfare: Keep to the right, pass on the left, maintain a respectable berth, and be ready to weave or change course to avoid oncoming obstacles while keeping up a steady walking pace.

Now engineers at MIT have designed an autonomous robot with “socially aware navigation,” that can keep pace with foot traffic while observing these general codes of pedestrian conduct.

In drive tests performed inside MIT’s Stata Center, the robot, which resembles a knee-high kiosk on wheels, successfully avoided collisions while keeping up with the average flow of pedestrians. The researchers have detailed their robotic design in a paper that they will present at the IEEE Conference on Intelligent Robots and Systems in September.

“Socially aware navigation is a central capability for mobile robots operating in environments that require frequent interactions with pedestrians,” says Yu Fan “Steven” Chen, who led the work as a former MIT graduate student and is the lead author of the study. “For instance, small robots could operate on sidewalks for package and food delivery. Similarly, personal mobility devices could transport people in large, crowded spaces, such as shopping malls, airports, and hospitals.”

Chen’s co-authors are graduate student Michael Everett, former postdoc Miao Liu, and Jonathan How, the Richard Cockburn Maclaurin Professor of Aeronautics and Astronautics at MIT.

Social drive

In order for a robot to make its way autonomously through a heavily trafficked environment, it must solve four main challenges: localization (knowing where it is in the world), perception (recognizing its surroundings), motion planning (identifying the optimal path to a given destination), and control (physically executing its desired path).

Chen and his colleagues used standard approaches to solve the problems of localization and perception. For the latter, they outfitted the robot with off-the-shelf sensors, such as webcams, a depth sensor, and a high-resolution lidar sensor. For the problem of localization, they used open-source algorithms to map the robot’s environment and determine its position. To control the robot, they employed standard methods used to drive autonomous ground vehicles.

“The part of the field that we thought we needed to innovate on was motion planning,” Everett says. “Once you figure out where you are in the world, and know how to follow trajectories, which trajectories should you be following?”

That’s a tricky problem, particularly in pedestrian-heavy environments, where individual paths are often difficult to predict. As a solution, roboticists sometimes take a trajectory-based approach, in which they program a robot to compute an optimal path that accounts for everyone's desired trajectories. These trajectories must be inferred from sensor data, because people don't explicitly tell the robot where they are trying to go. 

“But this takes forever to compute. Your robot is just going to be parked, figuring out what to do next, and meanwhile the person’s already moved way past it before it decides ‘I should probably go to the right,’” Everett says. “So that approach is not very realistic, especially if you want to drive faster.”

Others have used faster, “reactive-based” approaches, in which a robot is programmed with a simple model, using geometry or physics, to quickly compute a path that avoids collisions.

The problem with reactive-based approaches, Everett says, is the unpredictability of human nature — people rarely stick to a straight, geometric path, but rather weave and wander, veering off to greet a friend or grab a coffee. In such an unpredictable environment, such robots tend to collide with people or look like they are being pushed around by avoiding people excessively.

 “The knock on robots in real situations is that they might be too cautious or aggressive,” Everett says. “People don’t find them to fit into the socially accepted rules, like giving people enough space or driving at acceptable speeds, and they get more in the way than they help.”

Training days

The team found a way around such limitations, enabling the robot to adapt to unpredictable pedestrian behavior while continuously moving with the flow and following typical social codes of pedestrian conduct.

They used reinforcement learning, a type of machine learning approach, in which they performed computer simulations to train a robot to take certain paths, given the speed and trajectory of other objects in the environment. The team also incorporated social norms into this offline training phase, in which they encouraged the robot in simulations to pass on the right, and penalized the robot when it passed on the left.

“We want it to be traveling naturally among people and not be intrusive,” Everett says. “We want it to be following the same rules as everyone else.”

The advantage to reinforcement learning is that the researchers can perform these training scenarios, which take extensive time and computing power, offline. Once the robot is trained in simulation, the researchers can program it to carry out the optimal paths, identified in the simulations, when the robot recognizes a similar scenario in the real world.

The researchers enabled the robot to assess its environment and adjust its path, every one-tenth of a second. In this way, the robot can continue rolling through a hallway at a typical walking speed of 1.2 meters per second, without pausing to reprogram its route.

“We’re not planning an entire path to the goal — it doesn’t make sense to do that anymore, especially if you’re assuming the world is changing,” Everett says. “We just look at what we see, choose a velocity, do that for a tenth of a second, then look at the world again, choose another velocity, and go again. This way, we think our robot looks more natural, and is anticipating what people are doing.”

Crowd control

Everett and his colleagues test-drove the robot in the busy, winding halls of MIT’s Stata Building, where the robot was able to drive autonomously for 20 minutes at a time. It rolled smoothly with the pedestrian flow, generally keeping to the right of hallways, occasionally passing people on the left, and avoiding any collisions.

“We wanted to bring it somewhere where people were doing their everyday things, going to class, getting food, and we showed we were pretty robust to all that,” Everett says. “One time there was even a tour group, and it perfectly avoided them.”

Everett says going forward, he plans to explore how robots might handle crowds in a pedestrian environment.

“Crowds have a different dynamic than individual people, and you may have to learn something totally different if you see five people walking together,” Everett says. “There may be a social rule of, ‘Don’t move through people, don’t split people up, treat them as one mass.’ That’s something we’re looking at in the future.”

This research was funded by Ford Motor Company.  

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Back to school special

As part of this year’s freshman orientation at MIT, new students encountered the typical lineup of takeaways: booklets and brochures, a list of 101 things to do before they graduate, lots of T-shirts, pens, etc. For the first time, however, they were also given a completely new version of the old campus staple: the backpack.

Heaped into an uneven pyramid in the Coffeehouse, a room on the third floor of the Stratton Student Center that serves as orientation headquarters, there were dozens of bags — all with a seemingly identical black, white, and grey plaid design. They looked unassuming until Yoel Fink, professor of materials science, started talking to students about them: “These bags are the world’s first programmable backpacks!” he effused. The students leaned in closer, intrigued.

“We express our identity through the fabrics we wear,” said Fink. “And while each one of us is truly unique, the stuff we wear is certainly not,” he added. What if it were? What if our fabrics — say, the ones making up our backpacks — could communicate?

Thanks to Fink, now they can. A unique code is woven into the fabric material of the backpack given to each first-year student. Unlike a QR code, this fabric-based coding system is subtle to the eye but immediately recognizable by an app called AFFOA LOOKS. The owner can link his or her backpack to their mobile device and program it to display a song, a cause, or anything the owner chooses to share. Anyone with the app can scan or “look” the bag and receive this information (in Fink’s case, it’s his business card and a customized song of the day).

Fink is a co-inventor of the tech behind the bag and the CEO of Advanced Functional Fabrics of America (AFFOA). Located close to the MIT campus, the nonprofit institute was recently created through a $300 million proposal backed by federal and state governments, as well as academic and corporate partners, with the mission of creating functional fabrics that deliver value-added services while facilitating domestic manufacturing and economic growth in this area.

“The fabrics we wear have been functionally the same for centuries,” Fink explained to a packed house in Kresge Auditorium later in the day. “What we wanted to create was a fabric that is as unique as you are.” The manufacturing process employs special looms and materials, he explained. And the bags themselves are exclusive — not sold anywhere. They were made by Inman Mills in South Carolina just for the members of MIT’s Class of 2021.

The plan to give out the backpacks was first proposed by Katharina Ribbeck, a professor in the Department of Biological Engineering, who pointed out that the pack could help facilitate interactions and learning among incoming students. Her proposal was supported by Ian A. Waitz, MIT’s newly appointed vice chancellor and former dean of engineering, who saw it as an opportunity to give new students a way to directly engage with novel technology and each another (and a free place to store their gear and books). There are already plans for a hack-the-pack event during January’s Independent Activities Period.

For Fink, the functional aspect of the backpack is social in another way. Every first-year student he speaks with leaves with a broader understanding of the term “software” (as in soft wear). He wants incoming students to glean that manufacturing is undergoing a transformation; it’s as high-tech and as hot as coding, artificial intelligence, gene editing, and autonomy. It’s an option, a pursuit, a place for passion and a way for self-expression and creativity.

“If you are coming to MIT for the fist time,” he said, waving at the pile of coded bags behind him, “this is what is the place is all about. It’s about innovation and making a difference.” 

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Celebrating Walker Memorial’s 100th year

Labor Day Weekend of 1917 marked the opening of MIT’s new student center, Walker Memorial — although not for its intended purpose. As part of the Institute’s contribution to the World War I war effort, 400 naval aviation students moved into the new building, taking over the gymnasium and balconies of the big hall for dormitory space, as well as the rooms on the second and third floors that had been built for student and faculty recreational use.

The building’s namesake, former MIT President Francis Amasa Walker, is still the only MIT president to have served as a military general, so he likely would have approved. As The Tech of the day reported: “the building erected in memory of him will be devoted to military purposes before becoming what it is destined to be, the social center of Technology.”

A hub for campus activities was considered the greatest tribute to President Walker, who was beloved by both students and alumni for his efforts to improve student life on MIT’s cramped Boston campus. But making that ideal student center a reality took two decades.

When Walker died in 1897, the Alumni Association formed a committee to plan and fund the project, and, by 1902, the funds and land had been set aside. The project was postponed, though, when MIT announced plans to relocate from Boston. It wasn't until the Institute’s move to Cambridge 14 years later that construction on Walker Memorial finally became possible.

It became a landmark for MIT students began even before it was finished. On Feb. 9, 1917, the Class of 1918 gathered for “the first Class Photograph ever taken on the steps of Walker Memorial ... this spot will probably be chosen as a place to take all class pictures in the future,” the 1918 edition of Technique reported. The tradition holds generations later: Walker's steps are still used for alumni group portraits, most notably that of the 50th reunion class before they march in the Commencement procession as official Cardinal and Gray Society members in their distinctive red jackets.

After the Army and Navy aviation cadets moved out in January of 1919, the building was formally inaugurated as a student center. Henry A. Morss, Class of 1893 and then president of the Alumni Association, formally presented Walker Memorial to MIT “for the students that the student body would thereby be united and the Technology spirit be fostered.” 

For many of those who have passed through Walker Memorial over the past 100 years, the most enduring images remain the murals in Morss Hall, which were painted by Edwin Howland Blashfield of the Class of 1869. Created and installed between 1923 and 1930, their allegories of alma mater receiving homage from scientific and academic disciplines have watched over countless MIT community functions, from dining hall breakfasts to the Assembly Ball and more.

For most MIT alumni and students, Walker Memorial holds indelible memories. A century after its completion, the tribute to President Walker has been realized in the best possible way — with the building continuing to serve as a community gathering place.

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Experiencing the Great American Solar Eclipse

They came in droves to witness the moon blocking the sun.

On Aug. 21 at MIT's campus in Cambridge, Massachusetts; at the MIT Wallace Observatory; and in eastern Idaho, members of the MIT community, and the public at large, gathered to watch what was hailed by many as the Great American Solar Eclipse — a solar eclipse that could be seeen across North America.

The MIT Department of Earth, Atmospheric and Planetary Sciences (EAPS) hosted the main event on campus, at the Kresge Oval. Armed with solar glasses and viewing devices ranging from a pair of specially filtered telescopes to paper plates, colanders, and pinhole cameras, organizers enthusiastically greeted several thousand attendees who showed up to view the partial eclipse. Megan Jordan, EAPS academic administrator, said that the 300 pairs of solar glasses on hand were shared by attendees, whose presence far exceeded the expected turnout. The event, organized by senior lecturer Amanda Bosh and others in EAPS, was well staffed with volunteers, postdocs, and students, as well as individuals in the observe@MIT stargazing group.

In Westford, Massachusetts, the MIT Wallace Astrophysical Observatory and MIT Haystack Observatory co-hosted another lively eclipse party for nearly 200 people on the Wallace grounds — the largest public event ever at the observatory. Despite months of hype and excitement, the partial eclipse did not disappoint here, either. Families gathered on the lawn from as far away as Virgina to see what looked like a bite taken out of the sun. Cool temperatures and a dimmed sky during the height of the obscurement were clearly noticable, even though the moon covered just over 60 percent of the sun's surface. 

Several families built and transported carboard viewers larger than the children using them to safely watch the sun. MIT Wallace site manager Tim Brothers set up a telescope filtered for safe viewing, and the line of people waiting to look through it at the eclipse stretched through the grounds during the entire eclipse party. Brothers also set up a live feed from another telescope, this one equipped with an H-alpha filter that narrows the visible spectrum to view details in the sun's chromosphere layer, as well as a live data feed from the ionospheric radar experiment at MIT Haystack next door. 

Further afield, some 50 MIT alumni and family members traveled together with EAPS Professor Rick Binzel to Rexburg, Idaho, to experience the solar eclipse within the region of totality — a narrow band across the U.S. where the moon completely blocked out the sun. The location was chosen based on extensive research by Binzel to determine a spot most likely to have favorable weather and clear skies. The MIT group got up early to avoid expected traffic and spent the eclipse on Brigham Young University's Idaho campus. The group, carrying MIT flags and a variety of safe viewing devices, enjoyed the spectacle after hearing expert lectures from Binzel on the science of the eclipse.

Preparations are already underway for the next total solar eclipse across the United States in 2024, for which the path of totality will stretch from Texas to Maine.

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President Reif to Class of 2021: “We are very lucky to have you!”

MIT greeted the incoming Class of 2021 with its annual Convocation in front of Kresge Auditorium, treating them and their parents to personal stories of what it was like to first arrive at MIT, as told by President L. Rafael Reif and three highly accomplished faculty members.

Reif described his own fears when he arrived at this campus, having grown up in Venezuela, not knowing anyone in the area. He worried, among other things, about whether he was good enough to succeed here, whether his English was good enough, and what it would be like to experience snow for the first time. But those fears were quickly erased: “Very soon, MIT became my academic home,” he said, “and this community became my extended family. I hope that you will come to feel that way, too.”

Those initial fears vanished, he said, when “I found that what mattered at MIT was not where you come from or who you know, but what you contribute: good ideas, new perspectives, hard work, and creativity.” MIT, he said, “was the first place where I could stop feeling self-conscious, particularly about what interested me.”

Those initial worries were echoed by three faculty members who described their own experiences upon arriving here. Kristala Prather, the Arthur D. Little Professor of Chemical Engineering, who earned her bachelor’s degree at MIT, recalled thinking when she arrived on campus and heard of the amazing accomplishments of her fellow students, “how the heck did they let me in?” And, she added, she felt the same way 14 years later when she received her appointment to the MIT faculty.

To those in the incoming class who might feel the same way, she said, “I want to be sure you know, you are here on purpose. … You are ready to take on this place!”

“MIT is a unique crucible, where you will be faced with challenges you didn’t quite expect, at an important time of your life,” she said. “My advice here is quite simple: Embrace failure! If you haven’t already, you’ll soon realize that failures frequently, and I might say usually, allow you to learn far more than your successes.” Failure, she said, “lets you know that your knowledge lacked depth, or your understanding was incomplete, or maybe your expectations were a little unrealistic. Filling in those gaps adds to your knowledge base, and how you go about recovering from those failures will teach you lifelong lessons.”

Prather added that students should seek experiences outside their academic specialties. “You have to have balance, something that allows you to get away from the rigors of academics and enjoy life. … So my advice to you is to have fun, explore, try new things, go new places, meet new people, hang out with friends, just have fun … but not too much fun.”

Martin Culpepper, a professor of mechanical engineering and MIT’s “Maker Czar,” regaled the students with his own experiences of early failure and having fun, such as the time he took apart his dad’s carburetor and found that there were quite a few parts left over when he put it back together and it didn’t work, or when he flooded the basement of his home while trying to fix the washing machine. He learned important lessons from that, he said, such as “what an insurance deductible is, compared to my allowance.”

But these experiences, he explained, really did end up paving his path to MIT. And once he got here, “every day here as a student I got challenged, every day I got to see amazing things that people were doing in their research, and every day here as a student I got to work with my mind and my hands.”

Culpepper added that “over the course of the next few years, you’re going to have tough days.” He gave the example from his first semester, when a professor found out he couldn’t afford to go home for Thanksgiving, and invited him to spend it with his own family. He ended up having a wonderful experience there, having a great meal, driving bulldozers, and talking at length about differential equations. It was a day that could have been really sad for him, he said, but ended up being a fantastic experience.

Sara Seager, the Class of ’41 Professor, a professor of planetary science and of physics, and a leading expert on planets outside the solar system, talked about seeing the total solar eclipse a week ago. She described how that event related to the kind of research she has been carrying out for many years, to detect planets around other stars by observing the dimming of light when a planet passes in from of its star — a kind of miniature eclipse. Seager is a leader of the team that designed TESS, a new NASA mission that will soon observe many nearby stars to watch for such eclipses — called transits — in order to learn much more about the characteristics of those distant planets.

She described how she posed a challenge to a class in the Department of Aeronautics and Astronautics to develop a system to control the accurancy of pointing for tiny satellites called cubesats so that they could be steady enough to carry out such observations. The students rose to the challenge, and after some further development, this system was launched two weeks ago by NASA to the International Space Station, where it will soon be deployed into space. That whole experience, she said, “captured the MIT spirit: This bold idea that no matter how crazy, if it’s backed up by physics, it’s worth developing.” Where others might dismiss an idea as crazy, at MIT the attitude is “‘Yes, let’s give it a try,’” she said.

As Reif summarized to the incoming freshman class, “Every one of you has what it takes to succeed here. … And I hope you will join us in facing the challenge of building a better MIT, and building a better world. Humanity is facing no shortage of serious challenges: climate, energy, disease, poverty. And MIT is a magnificent human machine for inventing the future. But MIT invents the future thanks to its students.”

Reif concluded by thanking the incoming students for the choice they made: “We are very lucky to have you. All of you had other options, and I am delighted and grateful that you chose MIT. You will receive a great education here, and all of us together will make a better world.”

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Inspiring the next generation of engineers

The halls of MIT were abuzz with 30 children and teenagers eager to be civil and environmental engineers for a day.

All relatives, friends or neighbors of members of the Department of Civil and Environmental Engineering (CEE), the young additions to the community were on campus for the second annual CEE Kids Camp, a day filled with science, technology, engineering, and mathematics (STEM) activities that showcased research topics throughout the department.

“We started CEE Kids Camp last year to show friends and relatives of our community what it means to work in CEE and to inspire the next generation of STEM students,” said Markus Buehler, head of CEE and the McAfee Professor of Engineering. “All of the children were excited to attend the event and to share what they created throughout the day. The camp was a unique opportunity to sample the diverse research areas in CEE for young children to show them what it means to be a civil and environmental engineer.”

The one-day camp was held on Aug. 15, beginning with an orientation breakfast, where the group received schedules, camp shirts, bags, and CEE water bottles. The kids also learned about the environmental impact of disposable water bottles and the importance of using reusable ones — information that became trivia question material later in the day.

Led by volunteers from across the department, the camp consisted of seven stations featuring kid-friendly activities that exposed participants to a number of research areas, including fluid mechanics, concrete sustainability, earthquake-resistant structures, and bioinspired materials.

“All of the activities and presentations were created with kids of all ages in mind; you could tell that a lot of thought went into making sure that everything was at a level everyone could understand,” said Kathy Briana, the lead organizer of the camp and a CEE staff member. “It was a busy day hosting so many kids and teenagers, but it was a lot of fun.”  

The participants were broken into smaller groups and took turns rotating between stations, which were hosted by faculty members, lecturers, students, and department affiliates. The tasks had varying levels of difficulty, but volunteers were on hand to guide each child through the activities.

Assistant Professor Tal Cohen, who specializes in nonlinear solid mechanics and material instabilities, hosted a session that invited children to build their own structures using a magnetic modeling kit. Participants were challenged to figure out how to build a structurally-sound model, and then to build bridges connecting their structure to their neighbor’s creation.

“I was expecting them to be much more creative than adults are, and it was very obvious that they were thinking of all kinds of solutions that we probably wouldn’t have even attempted,” Cohen said. “Some of them managed to have buildings with moving objects, some of them built forts, and some managed to build the bridge.”

Admir Masic, the Esther and Harold E. Edgerton Career Development Professor, and graduate student Hyun Chae “Chad” Loh led a demonstration about bioinspired materials, explaining how learning about biological materials and their designs can be hugely beneficial for the creation of new, high-performance, and more sustainable building materials. During his hands-on presentation, Masic allowed the kids to touch corals, shells, giant squid sucker rings, and silk cocoons, and to use an optical microscope to explore the intricate details of various natural samples, including a deep sea sponge. There was stiff competition to use the microscope, but each member of the group later got to wear 3-D glasses to get another look at the materials’ structures on the nanoscale. They also asked Masic questions about his work.

Outside, Marie-Julie Dalbe, a postdoc in Professor Ruben Juanes’ group, and undergraduate exchange student Hannah Galbraith-Olive used bubbles to explain the basics of fluid mechanics. Dalbe and her peers study multiphase flow, which is essentially studying the interactions between bubbles of two different fluids like water and oil, so simplifying their research into soap bubbles was a natural activity for kids, she explained.

Using a homemade bubble solution of soap and glycerin, Dalbe and Galbraith-Olive helped the campers explore what bubbles are, why they pop, and how bubbles can bounce. The participants experimented with blowing bubbles using cut plastic pipettes, mixed and tested their own solutions, and used bubble makers made of wood and rope to run through DuPont Court and create giant bubbles in their wake.

“The idea was to show them how to strengthen bubbles, like how to make them bigger and last longer. My vision was to help the kids figure out why bubbles pop, but they always said: ‘Because we pop them,’ ” Dalbe said with a laugh. “The goal was to explain how bubbles pop naturally, and how we could change that with different solutions and conditions.”

During other sessions, the camp attendees had the opportunity to create their own souvenirs. Graduate student Linda Seymour, postdoc Diego López Barreiro, and computer-aided design operator Steve Rudolph helped the participants mix their own rapid-setting cement and design coasters in petri dishes to take home. While waiting for the cement to set, the participants engaged in one of three sub-activities: a laboratory scavenger hunt, activity questionnaires, or coloring sheets, selected based on the age of the group.

Seymour discussed the history of cement and her research into sustainable concrete mixtures. She also told the group about her recent research trip to Italy, and let the participants look at a piece of ancient Roman concrete.  

“It was a really great experience to share what we do and to get kids excited about engineering,” Seymour said. “I think it also really helped me as a researcher to think about how I’m presenting what I’m doing and being able to tailor my research to a diverse audience.”

The groups were also able to use the department’s advanced manufacturing equipment to create their own puzzles. The session, led by members the Laboratory for Atomistic and Molecular Mechanics (LAMM) including research scientists Zhao Qin and Francisco Martin-Martinez, graduate student Isabelle Su, and visiting scholar Flavia Libonati, invited the children to select images that would become the basis of a puzzle. The researchers then brought the students into the lab to see the laser cutter in action as it translated the images onto plastic and cut the material into puzzles for the participants to take home.  

As engineers for the day, the groups were also tasked with building, testing and improving a variety of tools and designs. Doug Shattuck, a LAMM research affiliate and teacher at nearby Concord Middle School, and Najia Lloyd, a student member of the MIT-Concord Middle School Research Team, set up four stations for the camp participants to show their creativity and to try to build functional and well-designed devices. Among the tasks were building a marshmallow catapult with tongue depressors; using a magnet, battery, and wire to make a spinning motor; using a spool and pencil to create a racing dragster; and making a flying paper vortex. Shattuck established his personal benchmarks before the camp began, but his records were quickly beaten, and the kids were challenged with beating the records again and again throughout the day.

Shattuck found that the marshmallow catapult was the most popular activity. “I think the kids who were interested could get their minds into it more; it was a little bit easier to understand, and they could make it as simple or complicated as they wanted,” he said. “On the other hand, everybody could do it. And if they really wanted to, they could eat the marshmallows — as long as they didn’t hit the floor.”

The camp participants also learned how structures respond to earthquakes, and the importance of creating and understanding properly-engineered structures. CEE lecturer Gordana Herning explained to the group how earthquakes occur, showed the students how earthquakes are recorded in online databases, and showed the extent of the damage that they cause around the world.

Next, Herning challenged the children to build their own structures using string, pipe cleaners, and K’Nex building sets, and to consider what needed to be included in the designs to make the structures more resilient. The final task was to test the structures against an earthquake simulation using a shake table. Some structures were able to withstand the movement, but others ended up warped by the simulated disaster. At the end of the session, Herning identified potential areas for improvement in each creation and showed how critical the right designs can be for durability.

CEE Kids Camp wrapped up with an ice cream sundae bar and plastic water bottle trivia, where attendees competed to answer questions about the use of disposable water bottles, showed off their creations, and indulged in sweet treats.  

“The kids were really impressive in all of the stations, and it was great to see them engaging with our researchers here at MIT throughout the day,” Buehler said. “Each year CEE Kids Camp improves, and it wouldn’t be possible without the help of our community members who volunteered time and energy towards making the event such a great success. We’re already looking forward to hosting the camp again next summer.”

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Strength of global stratospheric circulation measured for first time

When commercial airplanes break through the clouds to reach cruising altitude, they have typically arrived in the stratosphere, the second layer of Earth’s atmosphere. The air up there is dry and clear, and much calmer than the turbulent atmosphere we experience on the ground.

And yet, for all its seeming tranquility, the stratosphere can be a powerful conveyor belt, pulling air up from the Earth’s equatorial region and pushing it back down toward the poles in a continuously circulating pattern. The strength of this circulation can significantly impact the amount of water vapor, chemicals, and ozone transported around the planet.

Now scientists in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS) have for the first time determined the strength of the stratosphere’s circulation, based on observations of key chemicals traveling within this atmospheric layer.

In a paper published today in the journal Nature Geoscience, the team reports that the stratosphere pulls about 7 billion kilograms of air up through the tropics per second, worldwide, at an altitude of about 20 kilometers. The researchers estimate that the average parcel of air can spend about 1.5 years within this layer before circulating back down to lower layers of the atmosphere.

The new estimate can help scientists gauge where and for how long water vapor, ozone, and greenhouse gases remain within the stratosphere. Scientists can also use the team’s method to determine future changes in the stratosphere’s strength — essential information for tracking the recovery of the ozone hole and the progression of global warming.

The paper’s lead authors are Marianna Linz, a former PhD student in EAPS who is now a postdoc at the University of California at Los Angeles; and Alan Plumb, a professor emeritus in EAPS; along with researchers from New York University, Karlsruhe Institute of Technology, the National Center for Atmospheric Research, Cambridge University, and Caltech.

Chemical laps

The circulation of the stratosphere is known to scientists as the meridional overturning, referring to the pattern in which air is pulled up into the stratosphere near the equator and transported along the Earth’s meridians, or longitudinal lines, before being drawn back down at the poles. Scientists have attempted to measure the strength of this overturning circulation, concentrating mainly on the speed at which water vapor rises through the stratosphere near the equator.

“Others have looked at this region of the equator where they think most of the stuff is coming up, and they’ve tried to characterize this using water vapor,” Linz says. “But that’s just looking at this narrow region, and it’s difficult to infer what the rest of the circulation looks like.”

Linz, Plumb, and their colleagues took a more global approach, making use of atmospheric measurements of two atmospheric chemicals, sulfur hexafluoride and nitrous oxide, taken around the world by satellites, weather balloons, and aircraft. They considered these chemicals to be ideal candidates to track, as they have no “stratospheric sinks,” or methods by which the concentration of these gases would change once they reached the stratosphere.

“The thinking is that what goes up must come down,” Linz says.

The scientists compiled measurements of both chemicals between 2007 and 2011, with the idea of estimating how long these chemicals took to enter, then exit, the stratosphere. They culled through the measurements, noting each chemical’s concentrations in given parcels of air throughout the stratosphere

at various locations and altitudes.

In particular, they looked over time to identify parcels of air rising up in the tropics, and later, parcels of air with the same concentration of chemicals, being drawn back down at the poles.

They reasoned that the time lag between the rising and sinking would indicate the time that parcel spent in the stratosphere. A simple calculation, factoring in the total mass of air in the stratosphere, would yield the speed at which that parcel traveled through the stratosphere, which essentially reflects the strength of circulation.

“If you think of a racetrack, and someone doing a lap on that track, you can measure the time they entered the track, and the time they came out of it, and you can calculate their average speed around the track if you know the track distance,” Plumb explains. “So this is like that, in a way.”

The air up there

The team performed these calculations and averaged the results for various altitudes throughout the stratosphere. Their calculations for both chemicals agreed almost perfectly at lower altitudes of around 20 kilometers, yielding a circulation strength of about 7 billion kilograms per second — comparable in magnitude to the strength of the overturning circulation in the ocean. 

“The most important thing to know in terms of impacts on climate change and ozone is what this circulation strength is like at this lower altitude, because that’s what is supplying chemicals to the stratosphere,” Plumb says.

Linz and Plumb compared their estimate with predictions of stratospheric circulation made by several climate models, and found that their estimate agreed with some models but not others. Linz says the team’s new estimate, and the method to calculate the stratosphere’s strength, can help to improve model predictions of warming and ozone development.

“If climate models are getting their stratospheric circulation wrong, they’re probably getting their ozone distributions wrong, which will have definite impacts on what the [predicted] trends are for global warming,” Linz says. “So having this benchmark is really valuable.”

The researchers are working to obtain more measurements, higher in the stratosphere, to better characterize the stratosphere’s strength at higher altitudes as well as within lower layers.

“We have this data and can say what the strength is at this level, but because we don’t have the data higher up, we can’t say nearly as much. So we really do need better observations in the upper stratosphere,” Linz says.

This research was supported, in part, by the National Science Foundation.

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Danielle Wood joins Media Lab faculty

Danielle Wood ’05, SM ’08, PhD ’12 is the Media Lab’s newest assistant professor in the Program in Media Arts and Sciences. She will officially start working at the lab on Jan. 16, 2018, to establish a new research group, called Space Enabled. Her mission is to advance justice and development in Earth's complex systems using designs enabled by space.

“Let’s keep striving for the ideal that space really is for the benefit of all humankind,” Wood said at a Media Lab event in March when she took part in a panel discussion about the future of space research. A scholar of societal development with a background that includes satellite design, systems engineering, and technology policy for the U.S. and emerging nations, Wood added that “space research is just a link in a bigger chain, part of a broad system of technology and art and science and design.” Her passion, she said, has been in designing satellite systems that serve societal needs while integrating new technology.

Growing up in Orlando, where she frequently witnessed space shuttle launches, Wood was inspired by how NASA teams came together to achieve such precise and challenging missions. But she also wanted to find opportunities to serve people directly in her career. Ultimately, that combination of interests led her to study aerospace engineering, policy, and international development. As a doctoral student at MIT, Wood traveled to 15 countries over 10 months as part of in-depth research on new satellite programs in Africa and Asia. The study explained how governments can harness international collaboration to foster domestic capability building and national development.

“Danielle ties space, development, and earth sciences together in a unique and impactful, Media Lab-like way,” says Media Lab Director Joi Ito. He adds that she “fits perfectly into our community like the puzzle piece you’ve been looking for forever.”

Research priorities and plans

In setting up the new group, Space Enabled, Wood plans to reduce barriers to applying space technology for societal benefit. Her research pursues a four-fold cycle that includes observation, explanation, co-design, and evaluation of complex systems that deliver public sector services, using methods from engineering and social science. “I am particularly interested in areas such as environment, health care, education, and law enforcement,” Wood explains. “These public service systems foster justice and societal development when they provide equitable access and high-quality service to consumers across the socioeconomic spectrum.” To that end, her group will partner with communities in the U.S. and abroad on long-term projects to implement new designs enabled by capabilities from space, such as satellite-based earth observation.

Wood’s group will include researchers and staff who bring together “multiple, seemingly unrelated interests. Some of the skill sets relevant to the projects I plan to pursue include engineering, design, technology policy, law, social science, geography, earth science, public health, history, art, and data analytics.” The Space Enabled team will not work in isolation: Wood says she expects to collaborate with other research groups at the Media Lab and also contribute to its Space Exploration initiative.   

Currently, Wood serves as the applied sciences manager at NASA’s Goddard Space Flight Center, where she focuses on using earth science findings for societal applications, such as food security and water resource management. Previously, she served as special assistant and advisor to NASA’s deputy administrator, and prior to NASA, she worked at the Aerospace Corporation, Johns Hopkins University, and the United Nations Office of Outer Space Affairs.

MIT roots and inspiration

At MIT, Wood earned a PhD in systems engineering, a master's in aerospace engineering, a master's in technology policy, and a bachelor's in aerospace engineering. At the Media Lab’s “Beyond the Cradle” event in March, Wood said that during her time at the Institute she was inspired by the expansion of space activity around the world and the potential uses of data captured by satellites. “But the question then becomes, how does the average person take advantage of that information? I look forward to co-designing solutions with communities to empower them to use space to make their own lives better. This is important in areas like food security, disaster response, and monitoring the spread of diseases influenced by environmental factors.”

During her time at MIT, Wood was awarded five fellowships, not only from MIT but also from the National Science Foundation, the National Defense Science and Engineering Graduate program, and NASA’s Harriett G. Jenkins Predoctoral Fellowship Program.

Wood’s work has drawn widespread recognition. She has won grants from the Future Space Leaders Foundation (2016) and the National Science Foundation (2013), and she’s received awards from many organizations, including the Global Competitiveness Conference (2015), the International Astronautical Federation (2012) and NASA (2010). Wood has presented her research through many scholarly publications, conferences, and invited talks across Africa, Asia, Europe, Australia, and North America.

Wood says she’s excited to return to MIT with a new perspective shaped by her professional path thus far. “I have worked in government, academia, and the private sector, which gives me an understanding of how each community functions. This experience will help me build strong teams in my future research at the Media Lab.”

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Bradley Olsen: Designing polymers with novel features

Tiny sensors made of antibodies, protein nanospheres that can clean up toxic spills, and gels that could be injected into a wound to initiate healing are just a few of the innovations emerging from Bradley Olsen’s lab at MIT.

Olsen’s research is based on exploring the physical properties of new types of polymers, and taking advantage of those properties to design novel materials that could have many useful applications.

“My group is really interested in two things: designing materials to address important challenges, and understanding the fundamental science that’s necessary for materials design,” says Olsen, an associate professor who recently earned tenure in MIT’s Department of Chemical Engineering.

His lab, which includes 15 to 20 students and postdocs, pursues these approaches mainly in the field of protein-polymer chemistry, a relatively new discipline that involves incorporating proteins into polymer materials. He credits those students with many of the key discoveries that have yielded these novel materials.

“It’s a group effort,” he says. “I think the talent and wisdom of the team far exceeds anything I could do individually.”

Block by block

Growing up in Minneapolis, Olsen became interested in chemistry in high school and applied to MIT in part because he was drawn to the Undergraduate Research Opportunities Program (UROP), which allows undergraduates to conduct research in the labs of MIT faculty.

While majoring in chemical engineering, Olsen spent three years working in the lab of Karen Gleason, the Alexander and I. Michael Kasser Professor of Chemical Engineering. At the time, Gleason was developing early versions of a technique known as initiated chemical vapor deposition, which allows scientists to use gases to form thin polymer coatings on a surface.

As a graduate student at the University of California at Berkeley, Olsen began working on synthesizing a special kind of polymers known as block copolymers. These materials consist of alternating blocks of two different kinds of monomers, which are the building blocks for synthetic polymers such as plastics and rubber.

When these monomers are arranged in blocks, it gives the overall material special properties. For example, the material may contain two monomers that would normally separate into layers, the way oil and water do. If those two chemically dissimilar molecules are bound together in a block copolymer, they can’t form separate layers. Instead, block copolymers assemble themselves into special structures, such as spheres, cylinders, or sheets, that help to minimize the interactions between the two chemically different blocks. Such materials are now commonly used in many products, including elastomers, adhesives, and personal care products.

As a graduate student, Olsen studied how these kinds of polymers could be used to control the nanostructure of semiconducting polymers. Then, as a postdoc at Caltech, he worked on developing injectable hydrogels, which could potentially be used for wound healing and stopping blood flow.

While at Caltech, Olsen received an offer to return to MIT as a faculty member, which he found hard to resist. “MIT certainly has very good students and very good colleagues, and I definitely had some nostalgia for the Boston area,” he says. “It’s fun to be back here.”

Useful materials

At MIT, Olsen has continued to develop block copolymers for a wide range of applications. In one area of research, he is designing materials where one block is a polymer and the other is a protein such as an enzyme or an antibody. These materials could then be formed into extremely sensitive biosensors.

“With this high-density array of proteins, you can potentially increase sensitivity by maybe a factor of 100 or 1,000, or even more,” Olsen says.

Protein-polymer hybrids also could be useful new materials that mimic the properties of nylons or polyurethanes, which are petroleum-derived materials that are found in hard plastics, coatings, insulation, and many other products. These new hybrids could potentially be produced in “biorefineries,” using sustainable sources of renewable biomass and making a positive impact on the environment. 

Another potential application for block copolymers is detoxification, using spherical “nanoreactors” whose surfaces are coated with enzymes that could break down toxic chemicals from an oil spill. Olsen has also continued working on hydrogels, including the development of wound-healing materials, in collaboration with MIT’s Institute for Soldier Nanotechnologies. 

“The things we work on are selected because the type of polymer-protein chemistry has a potential competitive advantage, and we try to apply our designs in that area,” he says.

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Political science debuts on MITx

When he arrived from Princeton University three years ago, political science MIT Professor Evan Lieberman was determined to find new and engaging ways of presenting course content. “I wanted to understand the students here, figure out what materials would interest them, and make a teaching impact,” he says.

One result of his efforts was 17.571 (Engineering Democratic Development in Africa). Offered for the first time in spring 2017, the class gives students the chance to apply engineering thinking to challenges in the practice of democracy in different African nations.

But now Lieberman, the Total Chair on Contemporary Africa, is taking instructional innovation to an entirely new level — and to new audiences. His new course, Democracy and Development: Perspectives from Africa, is the first MIT Political Science class produced exclusively for edX, the multi-university online education platform.

“I’d always been interested in technology, and wondered if there was a way to use the opportunity of a MOOC [massive open online course] to share ideas and to generate broad discussion on the issues important to my research,” Lieberman says.  So in 2015, he eagerly responded to a call for proposals from MITx, the Institute's online learning division, which works with the larger edX program.

His seven-week course, which launches Sept. 26, will introduce students from around the world to the drivers of democratic development in contemporary Africa. Lieberman has tailored his approach to online learners who might lack knowledge of Africa and its political institutions, but who are nevertheless curious about the promise and problems of democratic politics in Africa and elsewhere.

In developing the course, Lieberman says his first thought “was to make sure that lots of African voices get incorporated.”

“I can’t hide the fact that I’m a white American teaching about Africa — hopefully a sensitive one — and I felt it was important that students hear directly from Africans themselves,” he says.

Guided by a syllabus tackling topics such as the legacy of slavery and colonial rule, accountability and service delivery, human rights and the judiciary, and digital tools of democracy, Lieberman set out to interview a range of key players in African nations where democratic political institutions have taken root in the past few decades.

With funding from both MITx and the Center for International Studies, he recorded conversations with more than 50 African academics, politicians, leaders and students, who highlight key ideas and frame case studies intended to spur online discussion.

For instance, one module (the term for an online class) showcases a panel interview with three attorneys from a leading South African law firm. They discuss the legal recourse available to ordinary citizens who are legally entitled to but denied such public goods as land, housing, and education.

“We look at the ways law firms and other public actors use courts to challenge the government when government fails to deliver on constitutionally-mandated rights,” says Lieberman.
 
Each module consists of short video segments, ranging from four to 18 minutes long, which include interview clips and portions of Lieberman’s lectures where he distills key points from the interviews and frames larger questions intended to prompt lively online discussions.

“I’m excited to see what people have to say, whether they think the arguments they hear are plausible,” he says. “I will encourage students to provide examples from their own nations, when they can, and think about how politics can be helpful in leading to positive outcomes for people.”

In addition to these discussions, Lieberman is incorporating quizzes and short writing assignments to ensure that his online audience is digesting not just the video clips, but also the reading assignments. He hopes that such rich content will appeal to learners no matter where they live.

“There are universal concerns about how people come together to make decisions such that everyone feels they are more or less respected and that that the rules of the game are fair,” he says. “The course is about Africa, where there are specific challenges to democratic government, but the questions and ideas that arise are relevant in any political context.”

Given the frequent caricatures of “African strongmen and obedient followers,” he notes that Americans in particular “will be amazed by how thoughtful and sophisticated are the wide range of political actors in Africa, who are innovating in democratic government.”

After nearly 18 months of storyboarding, production, and editing — “the equivalent of preparing for three courses,” he says — it will soon be launch time. At last count, over 700 students from more than 100 countries had enrolled.

Lieberman says he has every hope that this “huge undertaking” will live up to his expectations and become, for a community of online learners, “an immersive experience where they can explore materials in a self-paced way, think hard about important questions, and pursue them after the course is over.”

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