jueves, 16 de mayo de 2024

Researchers develop a detector for continuously monitoring toxic gases

Most systems used to detect toxic gases in industrial or domestic settings can be used only once, or at best a few times. Now, researchers at MIT have developed a detector that could provide continuous monitoring for the presence of these gases, at low cost.

The new system combines two existing technologies, bringing them together in a way that preserves the advantages of each while avoiding their limitations. The team used a material called a metal-organic framework, or MOF, which is highly sensitive to tiny traces of gas but whose performance quickly degrades, and combined it with a polymer material that is highly durable and easier to process, but much less sensitive.

The results are reported today in the journal Advanced Materials, in a paper by MIT professors Aristide Gumyusenge, Mircea Dinca, Heather Kulik, and Jesus del Alamo, graduate student Heejung Roh, and postdocs Dong-Ha Kim, Yeongsu Cho, and Young-Moo Jo.

Highly porous and with large surface areas, MOFs come in a variety of compositions. Some can be insulators, but the ones used for this work are highly electrically conductive. With their sponge-like form, they are effective at capturing molecules of various gases, and the sizes of their pores can be tailored to make them selective for particular kinds of gases. “If you are using them as a sensor, you can recognize if the gas is there if it has an effect on the resistivity of the MOF,” says Gumyusenge, the paper’s senior author and the Merton C. Flemings Career Development Assistant Professor of Materials Science and Engineering.

The drawback for these materials’ use as detectors for gases is that they readily become saturated, and then can no longer detect and quantify new inputs. “That’s not what you want. You want to be able to detect and reuse,” Gumyusenge says. “So, we decided to use a polymer composite to achieve this reversibility.”

The team used a class of conductive polymers that Gumyusenge and his co-workers had previously shown can respond to gases without permanently binding to them. “The polymer, even though it doesn’t have the high surface area that the MOFs do, will at least provide this recognize-and-release type of phenomenon,” he says.

The team combined the polymers in a liquid solution along with the MOF material in powdered form, and deposited the mixture on a substrate, where they dry into a uniform, thin coating. By combining the polymer, with its quick detection capability, and the more sensitive MOFs, in a one-to-one ratio, he says, “suddenly we get a sensor that has both the high sensitivity we get from the MOF and the reversibility that is enabled by the presence of the polymer.”

The material changes its electrical resistance when molecules of the gas are temporarily trapped in the material. These changes in resistance can be continuously monitored by simply attaching an ohmmeter to track the resistance over time. Gumyusenge and his students demonstrated the composite material’s ability to detect nitrogen dioxide, a toxic gas produced by many kinds of combustion, in a small lab-scale device. After 100 cycles of detection, the material was still maintaining its baseline performance within a margin of about 5 to 10 percent, demonstrating its long-term use potential.

In addition, this material has far greater sensitivity than most presently used detectors for nitrogen dioxide, the team reports. This gas is often detected after the use of stove ovens. And, with this gas recently linked to many asthma cases in the U.S., reliable detection in low concentrations is important. The team demonstrated that this new composite could detect, reversibly, the gas at concentrations as low as 2 parts per million.

While their demonstration was specifically aimed at nitrogen dioxide, Gumyusenge says, “we can definitely tailor the chemistry to target other volatile molecules,” as long as they are small polar analytes, “which tend to be most of the toxic gases.”

Besides being compatible with a simple hand-held detector or a smoke-alarm type of device, one advantage of the material is that the polymer allows it to be deposited as an extremely thin uniform film, unlike regular MOFs, which are generally in an inefficient powder form. Because the films are so thin, there is little material needed and production material costs could be low; the processing methods could be typical of those used for industrial coating processes. “So, maybe the limiting factor will be scaling up the synthesis of the polymers, which we’ve been synthesizing in small amounts,” Gumyusenge says.

“The next steps will be to evaluate these in real-life settings,” he says. For example, the material could be applied as a coating on chimneys or exhaust pipes to continuously monitor gases through readings from an attached resistance monitoring device. In such settings, he says, “we need tests to check if we truly differentiate it from other potential contaminants that we might have overlooked in the lab setting. Let’s put the sensors out in real-world scenarios and see how they do.”

The work was supported by the MIT Climate and Sustainability Consortium (MCSC), the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS) at MIT, and the U.S. Department of Energy.



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Jeong Min Park earns 2024 Schmidt Science Fellowship

Physics graduate student Jeong Min (Jane) Park is among the 32 exceptional early-career scientists worldwide chosen to receive the prestigious 2024 Schmidt Science Fellows award.  

As a 2024 Schmidt Science Fellow, Park’s postdoctoral work will seek to directly detect phases that could host new particles by employing an instrument that can visualize subatomic-scale phenomena.  

With her advisor, Pablo Jarillo-Herrero, the Cecil and Ida Green Professor of Physics, Park’s research at MIT focuses on discovering novel quantum phases of matter.

“When there are many electrons in a material, their interactions can lead to collective behaviors that are not expected from individual particles, known as emergent phenomena,” explains Park. “One example is superconductivity, where interacting electrons combine together as a pair at low temperatures to conduct electricity without energy loss.”

During her PhD studies, she has investigated novel types of superconductivity by designing new materials with targeted interactions and topology. In particular, she used graphene, atomically thin two-dimensional layers of graphite, the same material as pencil lead, and turned it into a “magic” material. This so-called magic-angle twisted trilayer graphene provided an extraordinarily strong form of superconductivity that is robust under high magnetic fields. Later, she found a whole “magic family” of these materials, elucidating the key mechanisms behind superconductivity and interaction-driven phenomena. These results have provided a new platform to study emergent phenomena in two dimensions, which can lead to innovations in electronics and quantum technology.

Park says she is looking forward to her postdoctoral studies with Princeton University physics professor Ali Yazdani's lab.

“I’m excited about the idea of discovering and studying new quantum phenomena that could further the understanding of fundamental physics,” says Park. “Having explored interaction-driven phenomena through the design of new materials, I’m now aiming to broaden my perspective and expertise to address a different kind of question, by combining my background in material design with the sophisticated local-scale measurements that I will adopt during my postdoc.”

She explains that elementary particles are classified as either bosons or fermions, with contrasting behaviors upon interchanging two identical particles, referred to as exchange statistics; bosons remain unchanged, while fermions acquire a minus sign in their quantum wavefunction.

Theories predict the existence of fundamentally different particles known as non-abelian anyons, whose wavefunctions braid upon particle exchange. Such a braiding process can be used to encode and store information, potentially opening the door to fault-tolerant quantum computing in the future.

Since 2018, this prestigious postdoctoral program has sought to break down silos among scientific fields to solve the world’s biggest challenges and support future leaders in STEM.

Schmidt Science Fellows, an initiative of Schmidt Sciences, delivered in partnership with the Rhodes Trust, identifies, develops, and amplifies the next generation of science leaders, by building a community of scientists and supporters of interdisciplinary science and leveraging this network to drive sector-wide change. The 2024 fellows consist of 17 nationalities across North America, Europe, and Asia.   

Nominated candidates undergo a rigorous selection process that includes a paper-based academic review with panels of experts in their home disciplines and final interviews with panels, including senior representatives from across many scientific disciplines and different business sectors.  



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miércoles, 15 de mayo de 2024

Elaine Liu: Charging ahead

MIT senior Elaine Siyu Liu doesn’t own an electric car, or any car. But she sees the impact of electric vehicles (EVs) and renewables on the grid as two pieces of an energy puzzle she wants to solve.

The U.S. Department of Energy reports that the number of public and private EV charging ports nearly doubled in the past three years, and many more are in the works. Users expect to plug in at their convenience, charge up, and drive away. But what if the grid can’t handle it?

Electricity demand, long stagnant in the United States, has spiked due to EVs, data centers that drive artificial intelligence, and industry. Grid planners forecast an increase of 2.6 percent to 4.7 percent in electricity demand over the next five years, according to data reported to federal regulators. Everyone from EV charging-station operators to utility-system operators needs help navigating a system in flux.

That’s where Liu’s work comes in.

Liu, who is studying mathematics and electrical engineering and computer science (EECS), is interested in distribution — how to get electricity from a centralized location to consumers. “I see power systems as a good venue for theoretical research as an application tool,” she says. “I'm interested in it because I'm familiar with the optimization and probability techniques used to map this level of problem.”

Liu grew up in Beijing, then after middle school moved with her parents to Canada and enrolled in a prep school in Oakville, Ontario, 30 miles outside Toronto.

Liu stumbled upon an opportunity to take part in a regional math competition and eventually started a math club, but at the time, the school’s culture surrounding math surprised her. Being exposed to what seemed to be some students’ aversion to math, she says, “I don’t think my feelings about math changed. I think my feelings about how people feel about math changed.”

Liu brought her passion for math to MIT. The summer after her sophomore year, she took on the first of the two Undergraduate Research Opportunity Program projects she completed with electric power system expert Marija Ilić, a joint adjunct professor in EECS and a senior research scientist at the MIT Laboratory for Information and Decision Systems.

Predicting the grid

Since 2022, with the help of funding from the MIT Energy Initiative (MITEI), Liu has been working with Ilić on identifying ways in which the grid is challenged.

One factor is the addition of renewables to the energy pipeline. A gap in wind or sun might cause a lag in power generation. If this lag occurs during peak demand, it could mean trouble for a grid already taxed by extreme weather and other unforeseen events.

If you think of the grid as a network of dozens of interconnected parts, once an element in the network fails — say, a tree downs a transmission line — the electricity that used to go through that line needs to be rerouted. This may overload other lines, creating what’s known as a cascade failure.

“This all happens really quickly and has very large downstream effects,” Liu says. “Millions of people will have instant blackouts.”

Even if the system can handle a single downed line, Liu notes that “the nuance is that there are now a lot of renewables, and renewables are less predictable. You can't predict a gap in wind or sun. When such things happen, there’s suddenly not enough generation and too much demand. So the same kind of failure would happen, but on a larger and more uncontrollable scale.”

Renewables’ varying output has the added complication of causing voltage fluctuations. “We plug in our devices expecting a voltage of 110, but because of oscillations, you will never get exactly 110,” Liu says. “So even when you can deliver enough electricity, if you can't deliver it at the specific voltage level that is required, that’s a problem.”

Liu and Ilić are building a model to predict how and when the grid might fail. Lacking access to privatized data, Liu runs her models with European industry data and test cases made available to universities. “I have a fake power grid that I run my experiments on,” she says. “You can take the same tool and run it on the real power grid.”

Liu’s model predicts cascade failures as they evolve. Supply from a wind generator, for example, might drop precipitously over the course of an hour. The model analyzes which substations and which households will be affected. “After we know we need to do something, this prediction tool can enable system operators to strategically intervene ahead of time,” Liu says.

Dictating price and power

Last year, Liu turned her attention to EVs, which provide a different kind of challenge than renewables.

In 2022, S&P Global reported that lawmakers argued that the U.S. Federal Energy Regulatory Commission’s (FERC) wholesale power rate structure was unfair for EV charging station operators.

In addition to operators paying by the kilowatt-hour, some also pay more for electricity during peak demand hours. Only a few EVs charging up during those hours could result in higher costs for the operator even if their overall energy use is low.

Anticipating how much power EVs will need is more complex than predicting energy needed for, say, heating and cooling. Unlike buildings, EVs move around, making it difficult to predict energy consumption at any given time. “If users don't like the price at one charging station or how long the line is, they'll go somewhere else,” Liu says. “Where to allocate EV chargers is a problem that a lot of people are dealing with right now.”

One approach would be for FERC to dictate to EV users when and where to charge and what price they'll pay. To Liu, this isn’t an attractive option. “No one likes to be told what to do,” she says.

Liu is looking at optimizing a market-based solution that would be acceptable to top-level energy producers — wind and solar farms and nuclear plants — all the way down to the municipal aggregators that secure electricity at competitive rates and oversee distribution to the consumer.

Analyzing the location, movement, and behavior patterns of all the EVs driven daily in Boston and other major energy hubs, she notes, could help demand aggregators determine where to place EV chargers and how much to charge consumers, akin to Walmart deciding how much to mark up wholesale eggs in different markets.

Last year, Liu presented the work at MITEI’s annual research conference. This spring, Liu and Ilić are submitting a paper on the market optimization analysis to a journal of the Institute of Electrical and Electronics Engineers.

Liu has come to terms with her early introduction to attitudes toward STEM that struck her as markedly different from those in China. She says, “I think the (prep) school had a very strong ‘math is for nerds’ vibe, especially for girls. There was a ‘why are you giving yourself more work?’ kind of mentality. But over time, I just learned to disregard that.”

After graduation, Liu, the only undergraduate researcher in Ilić’s MIT Electric Energy Systems Group, plans to apply to fellowships and graduate programs in EECS, applied math, and operations research.

Based on her analysis, Liu says that the market could effectively determine the price and availability of charging stations. Offering incentives for EV owners to charge during the day instead of at night when demand is high could help avoid grid overload and prevent extra costs to operators. “People would still retain the ability to go to a different charging station if they chose to,” she says. “I'm arguing that this works.”



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The MIT Bike Lab: A place for community, hands-on learning

Bianca Champenois SM ’22 learned to ride a bike when she was 5 years old. She can still hear her sister yelling “equal elbows!” as she pushed her off into the street. Although she started young, her love of bikes really materialized when she was in college.

Champenois studied mechanical engineering (MechE) at the University of California at Berkeley, but with a first-year schedule comprising mostly prerequisites, she found herself wanting more hands-on opportunities. She stumbled upon BicyCal, the university’s bike cooperative.

“I loved the club because it was a space where learning was encouraged, mistakes were forgiven, and vibes were excellent,” explains Champenois. “I loved how every single bike that came into the shop was slightly different, which meant that no two problems were the same.”

Through the co-op’s hands-on learning experience, the few long rides she took across some of California’s bridges like the Golden Gate, and the lively evening “Bike Parties” drafting behind friends, Champenois’s love for biking continued to grow. When she arrived at MIT for her master’s studies, she joined the cycling team.

Champenois, who is also passionate about climate action, enjoyed the sense of community the cycling team offered, but was looking for something that also allowed her to solve problems and work on bikes again.

After discovering there wasn’t a comparable cooperative bike program at the Institute, Champenois was determined to start one herself. It wasn’t long before she secured club funding from The Coop’s Public Service Grant with the support of her peer, Haley Higginbotham ’21, who was also passionate about the cause. By the end of the year, the team had gained two more volunteers, civil and environmental engineering graduate student Matthew Goss and materials science and engineering grad student Gavin Winter, and the MIT Bike Lab was born.

"The idea is to empower people to learn how to fix their own bike so that they are motivated to use biking as a reliable transportation method," says Champenois. The volunteer mechanic has a vested interest in promoting sustainability and improving urban infrastructure.

Champenois is a graduate student in the joint Mechanical Engineering and Computational Science/Engineering program, and her research involves applying data science and machine learning to fluid dynamics, with a specific focus on ocean and climate modeling. The NSF Graduate Research Fellow is now building upon prior research focused on ocean acidification as part of her PhD thesis, while she is also involved in other projects within Professor Themis Sapsis’s Stochastic Analysis and Nonlinear Dynamics (SAND) Lab.

“I appreciate that my research strikes a balance between more applied environmental projects and more theoretical statistics and computational science,” she explains while referencing a recent research contribution to a project focused on improving global climate simulations.

Champenois’s academic research focus may be specific, but she stresses that the Bike Lab isn’t targeted to any particular interest and welcomes all who are eager to learn.

“If you're interested in solid mechanics, you can think about bike frames. If you're interested in material science, you can think about brake pads. If you're interested in fluids, you can think about hydraulic brakes,” she says. “I think there's something for everyone, and there's always something to learn.”                            

In the last year-and-a-half, the Bike Lab is estimated to have serviced over 150 bikes, and they’re only getting started. Champenois is ambitious about the Bike Lab’s future.

“I hope to teach classes, maybe throughout the semester or as a standalone IAP [Independent Activities Period] course. I am also really interested in the idea of managing a vending machine for parts,” states Champenois.

In the winter, the Bike Lab stores its tools in N52-318, but the club lacks the space needed to expand. “Without our own space, it is difficult for us to store parts, which means that people are required to bring their own parts if their repair requires a replacement,” explains Champenois.

While physical space isn’t required to build a sense of community, Champenois envisions the Bike Lab exuding the same sort of camaraderie as the Banana Lounge, another of one MIT’s student-run spaces, one day.

“I like to think of the Bike Lab as more than just a bike shop. It's also a place for community,” she says.

Champenois hopes to complete her degree in the next year or two and would like to become a professor someday. She is excited by a career in academia, but she says she could also see herself working on a climate or weather research team or joining an ocean technology startup.

Many have heard the expression that being a student at MIT is like “drinking from a firehose,” but that is one of the things Champenois will miss most when she leaves.

“I have had the opportunity to discover so many new hobbies and been able to learn so much through sponsored activities,” she recalls. “Most importantly, I'll miss the great people I have met. Everyone at MIT is so curious and hardworking in a way that is truly energizing.”



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Repurposed beer yeast may offer a cost-effective way to remove lead from water

Every year, beer breweries generate and discard thousands of tons of surplus yeast. Researchers from MIT and Georgia Tech have now come up with a way to repurpose that yeast to absorb lead from contaminated water.

Through a process called biosorption, yeast can quickly absorb even trace amounts of lead and other heavy metals from water. The researchers showed that they could package the yeast inside hydrogel capsules to create a filter that removes lead from water. Because the yeast cells are encapsulated, they can be easily removed from the water once it’s ready to drink.

“We have the hydrogel surrounding the free yeast that exists in the center, and this is porous enough to let water come in, interact with yeast as if they were freely moving in water, and then come out clean,” says Patricia Stathatou, a former postdoc at the MIT Center for Bits and Atoms, who is now a research scientist at Georgia Tech and an incoming assistant professor at Georgia Tech’s School of Chemical and Biomolecular Engineering. “The fact that the yeast themselves are bio-based, benign, and biodegradable is a significant advantage over traditional technologies.”

The researchers envision that this process could be used to filter drinking water coming out of a faucet in homes, or scaled up to treat large quantities of water at treatment plants.

MIT graduate student Devashish Gokhale and Stathatou are the lead authors of the study, which appears today in the journal RSC Sustainability. Patrick Doyle, the Robert T. Haslam Professor of Chemical Engineering at MIT, is the senior author of the paper, and Christos Athanasiou, an assistant professor of aerospace engineering at Georgia Tech and a former visiting scholar at MIT, is also an author.

Absorbing lead

The new study builds on work that Stathatou and Athanasiou began in 2021, when Athanasiou was a visiting scholar at MIT’s Center for Bits and Atoms. That year, they calculated that waste yeast discarded from a single brewery in Boston would be enough to treat the city’s entire water supply.

Through biosorption, a process that is not fully understood, yeast cells can bind to and absorb heavy metal ions, even at challenging initial concentrations below 1 part per million. The MIT team found that this process could effectively decontaminate water with low concentrations of lead. However, one key obstacle remained, which was how to remove yeast from the water after they absorb the lead.

In a serendipitous coincidence, Stathatou and Athanasiou happened to present their research at the AIChE Annual Meeting in Boston in 2021, where Gokhale, a student in Doyle’s lab, was presenting his own research on using hydrogels to capture micropollutants in water. The two sets of researchers decided to join forces and explore whether the yeast-based strategy could be easier to scale up if the yeast were encapsulated in hydrogels developed by Gokhale and Doyle.

“What we decided to do was make these hollow capsules — something like a multivitamin pill, but instead of filling them up with vitamins, we fill them up with yeast cells,” Gokhale says. “These capsules are porous, so the water can go into the capsules and the yeast are able to bind all of that lead, but the yeast themselves can’t escape into the water.”

The capsules are made from a polymer called polyethylene glycol (PEG), which is widely used in medical applications. To form the capsules, the researchers suspend freeze-dried yeast in water, then mix them with the polymer subunits. When UV light is shone on the mixture, the polymers link together to form capsules with yeast trapped inside.

Each capsule is about half a millimeter in diameter. Because the hydrogels are very thin and porous, water can easily pass through and encounter the yeast inside, while the yeast remain trapped.

In this study, the researchers showed that the encapsulated yeast could remove trace lead from water just as rapidly as the unencapsulated yeast from Stathatou and Athanasiou’s original 2021 study.

Scaling up

Led by Athanasiou, the researchers tested the mechanical stability of the hydrogel capsules and found that the capsules and the yeast inside can withstand forces similar to those generated by water running from a faucet. They also calculated that the yeast-laden capsules should be able to withstand forces generated by flows in water treatment plants serving several hundred residences.

“Lack of mechanical robustness is a common cause of failure of previous attempts to scale-up biosorption using immobilized cells; in our work we wanted to make sure that this aspect is thoroughly addressed from the very beginning to ensure scalability,” Athanasiou says.

After assessing the mechanical robustness of the yeast-laden capsules, the researchers constructed a proof-of-concept packed-bed biofilter, capable of treating trace lead-contaminated water and meeting U.S. Environmental Protection Agency drinking water guidelines while operating continuously for 12 days.

This process would likely consume less energy than existing physicochemical processes for removing trace inorganic compounds from water, such as precipitation and membrane filtration, the researchers say.

This approach, rooted in circular economy principles, could minimize waste and environmental impact while also fostering economic opportunities within local communities. Although numerous lead contamination incidents have been reported in various locations in the United States, this approach could have an especially significant impact in low-income areas that have historically faced environmental pollution and limited access to clean water, and may not be able to afford other ways to remediate it, the researchers say.

“We think that there’s an interesting environmental justice aspect to this, especially when you start with something as low-cost and sustainable as yeast, which is essentially available anywhere,” Gokhale says.

The researchers are now exploring strategies for recycling and replacing the yeast once they’re used up, and trying to calculate how often that will need to occur. They also hope to investigate whether they could use feedstocks derived from biomass to make the hydrogels, instead of fossil-fuel-based polymers, and whether the yeast can be used to capture other types of contaminants.

“Moving forward, this is a technology that can be evolved to target other trace contaminants of emerging concern, such as PFAS or even microplastics,” Stathatou says. “We really view this as an example with a lot of potential applications in the future.”

The research was funded by the Rasikbhai L. Meswani Fellowship for Water Solutions, the MIT Abdul Latif Jameel Water and Food Systems Lab (J-WAFS), and the Renewable Bioproducts Institute at Georgia Tech.



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Newly discovered Earth-sized planet may lack an atmosphere

Astronomers at MIT, the University of Liège, and elsewhere have discovered a new planet orbiting a small cold star, a mere 55 light years away. The nearby planet is similar to Earth in its size and rocky composition, though that’s where the similarities end. Because this new world is likely missing an atmosphere.

In a paper appearing today in Nature Astronomy, the researchers confirm the detection of SPECULOOS-3b, an Earth-sized, likely airless planet that the team discovered using a network of telescopes as part of the SPECULOOS (Search for Planets EClipsing ULtra-cOOl Stars) project.

The new planet orbits a nearby ultracool dwarf — a type of star that is smaller and colder than the sun. Ultracool dwarf stars are thought to be the most common type of star in our galaxy, though they are also the faintest, making them difficult to spot in the night sky.

The ultracool dwarf that hosts the new planet is about one-tenth the size of, and 1,000 times dimmer than, the sun. The star is more similar in size to Jupiter and is twice as cold as the sun. Nevertheless, the dwarf star radiates an enormous amount of energy onto the planet’s surface due to the planet’s extremely close proximity: SPECULOOS-3b circles its star in just 17 hours. One year on the new planet, then, is shorter than one day on Earth.

Because it is so close to its star, the planet is blasted with 16 times more radiation per second compared to what the Earth receives from the sun. The team believes that such intense and relentless exposure has likely vaporized any atmosphere that the planet once held, leaving it an airless, exposed, blistering ball of rock.

If the planet lacks an atmosphere, scientists might soon be able to zero in on exactly what type of rocks are on its surface and even what sort of geological processes shaped its landscape, such as whether the planet’s crust experienced magma oceans, volcanic activity, and plate tectonics in its past.

“SPECULOOS-3b is the first planet for which we can consider moving toward constraining surface properties of planets beyond the solar system,” says study co-author Julien de Wit, associate professor of planetary sciences at MIT. “With this world, we could basically start doing exoplanetary geology. How cool is that?”

The study’s MIT co-authors include research scientists Benjamin Rackham and Artem Burdanov, along with lead author Michel Gillon of the University of Liège and colleagues from collaborating institutions and observatories around the world.

Lining up

Astronomers observed the first inklings of the new planet in 2021, with observations taken by SPECULOOS — a network of six robotic, 1-meter telescopes (four in the Southern Hemisphere, and two in the Northern Hemisphere) that continuously observe the sky for signs of planets orbiting around ultracool dwarf stars. SPECULOOS is the parent project of the TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope-South) survey, which discovered seven terrestrial planets — several potentially habitable — around a small cold star named TRAPPIST-1.

SPECULOOS aims to observe about 1,600 nearby ultracool dwarf stars. As these stars are small, any planets that orbit and cross in front of them should momentarily block their light, by a more noticeable amount compared to planets that orbit around larger, brighter stars. Ultracool dwarf stars, then, could give astronomers a better view of any planets that they host.

In 2021, a telescope in SPECULOOS’ network picked up some inconclusive signs of a transit, in front of one ultracool dwarf star about 55 light years away. Then in 2022, a close monitoring with MIT’s Artemis telescope changed the game.

“While there were structures in the 2021 data that didn’t look convincing, the 2022 Artemis data really got our attention,” recalls MIT’s Artem Burdanov, who manages the SPECULOOS Northern Observatory. “We started to analyze one clear transit-like signal in the Artemis data, quickly decided to launch a campaign around this star, and then things just started lining up.”

Dark like the moon

The team zeroed in on the star with MIT’s Artemis telescope, the rest of the SPECULOOS network, and several other observatories. The multipronged observations confirmed that the star did indeed host a planet, which appeared to orbit every 17 hours. Judging from the amount of light it blocked with each crossing, the scientists estimate that the planet is about the size of the Earth.

They were then able to estimate certain properties of the star and the planet based on analyses of the star’s light taken by MIT’s Benjamin Rackham, who has led a campaign using the Magellan telescopes in Chile and the NASA Infrared Telescope Facility (IRTF) in Hawaii to analyze the light from nearby ultracool dwarf stars.

“We can say from our spectra and other observations that the star has a temperature of about 2,800 kelvins, it is about 7 billion years old — not too young, and not too old — and it is moderately active, meaning that it flares quite a lot,” Rackham says. “We think the planet must not have an atmosphere anymore because it would easily have been eroded away by the activity of the host star that’s basically constantly flaring.”

Without an atmosphere, then, what might one see if they were to look up from the planet’s surface?

“If there’s no atmosphere, there would be no blue sky or clouds — it would just be dark, like on the surface of the moon,” Rackham offers. “And the ‘sun’ would be a big, purplish-red, spotted, and flaring star that would look about 18 times as big as the sun looks to us in the sky.”

Because the planet lacks an atmosphere and is relatively close by, the team says that SPECULOOS-3b is an ideal candidate for follow-up studies by NASA’s James Webb Space Telescope (JWST), which is powerful enough to parse the star’s light and discern more details of both the star and the planet. With JWST’s observations, the team hopes to be able to identify details of the planet’s surface, which would be a first in the field of exoplanetary studies.

“We think that the planet is nearly as hot as Venus, so not habitable,” Rackham says. “It’s not hot enough to have a lava surface. It should be solid rock. But depending on how bright that rock is, it could be recently resurfaced due to plate tectonics or volcanic activity, or it could be a planet that’s been eroded by space weathering and has a much darker surface. Going forward, we should be able to distinguish between some interesting scenarios for the surface of the planet.”

This research was supported, in part, by the European Research Council, the Simons Foundation, and the Heising-Simons Foundation.



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martes, 14 de mayo de 2024

Robotic “SuperLimbs” could help moonwalkers recover from falls

Need a moment of levity? Try watching videos of astronauts falling on the moon. NASA’s outtakes of Apollo astronauts tripping and stumbling as they bounce in slow motion are delightfully relatable.

For MIT engineers, the lunar bloopers also highlight an opportunity to innovate.

“Astronauts are physically very capable, but they can struggle on the moon, where gravity is one-sixth that of Earth’s but their inertia is still the same. Furthermore, wearing a spacesuit is a significant burden and can constrict their movements,” says Harry Asada, professor of mechanical engineering at MIT. “We want to provide a safe way for astronauts to get back on their feet if they fall.”

Asada and his colleagues are designing a pair of wearable robotic limbs that can physically support an astronaut and lift them back on their feet after a fall. The system, which the researchers have dubbed Supernumerary Robotic Limbs or “SuperLimbs” is designed to extend from a backpack, which would also carry the astronaut’s life support system, along with the controller and motors to power the limbs.

The researchers have built a physical prototype, as well as a control system to direct the limbs, based on feedback from the astronaut using it. The team tested a preliminary version on healthy subjects who also volunteered to wear a constrictive garment similar to an astronaut’s spacesuit. When the volunteers attempted to get up from a sitting or lying position, they did so with less effort when assisted by SuperLimbs, compared to when they had to recover on their own.

The MIT team envisions that SuperLimbs can physically assist astronauts after a fall and, in the process, help them conserve their energy for other essential tasks. The design could prove especially useful in the coming years, with the launch of NASA’s Artemis mission, which plans to send astronauts back to the moon for the first time in over 50 years. Unlike the largely exploratory mission of Apollo, Artemis astronauts will endeavor to build the first permanent moon base — a physically demanding task that will require multiple extended extravehicular activities (EVAs).

“During the Apollo era, when astronauts would fall, 80 percent of the time it was when they were doing excavation or some sort of job with a tool,” says team member and MIT doctoral student Erik Ballesteros. “The Artemis missions will really focus on construction and excavation, so the risk of falling is much higher. We think that SuperLimbs can help them recover so they can be more productive, and extend their EVAs.”

Asada, Ballesteros, and their colleagues will present their design and study this week at the IEEE International Conference on Robotics and Automation (ICRA). Their co-authors include MIT postdoc Sang-Yoep Lee and Kalind Carpenter of the Jet Propulsion Laboratory.

Taking a stand

The team’s design is the latest application of SuperLimbs, which Asada first developed about a decade ago and has since adapted for a range of applications, including assisting workers in aircraft manufacturing, construction, and ship building.

Most recently, Asada and Ballesteros wondered whether SuperLimbs might assist astronauts, particularly as NASA plans to send astronauts back to the surface of the moon.

“In communications with NASA, we learned that this issue of falling on the moon is a serious risk,” Asada says. “We realized that we could make some modifications to our design to help astronauts recover from falls and carry on with their work.”

The team first took a step back, to study the ways in which humans naturally recover from a fall. In their new study, they asked several healthy volunteers to attempt to stand upright after lying on their side, front, and back.

The researchers then looked at how the volunteers’ attempts to stand changed when their movements were constricted, similar to the way astronauts’ movements are limited by the bulk of their spacesuits. The team built a suit to mimic the stiffness of traditional spacesuits, and had volunteers don the suit before again attempting to stand up from various fallen positions. The volunteers’ sequence of movements was similar, though required much more effort compared to their unencumbered attempts.

The team mapped the movements of each volunteer as they stood up, and found that they each carried out a common sequence of motions, moving from one pose, or “waypoint,” to the next, in a predictable order.

“Those ergonomic experiments helped us to model in a straightforward way, how a human stands up,” Ballesteros says. “We could postulate that about 80 percent of humans stand up in a similar way. Then we designed a controller around that trajectory.”

Helping hand

The team developed software to generate a trajectory for a robot, following a sequence that would help support a human and lift them back on their feet. They applied the controller to a heavy, fixed robotic arm, which they attached to a large backpack. The researchers then attached the backpack to the bulky suit and helped volunteers back into the suit. They asked the volunteers to again lie on their back, front, or side, and then had them attempt to stand as the robot sensed the person’s movements and adapted to help them to their feet.

Overall, the volunteers were able to stand stably with much less effort when assisted by the robot, compared to when they tried to stand alone while wearing the bulky suit.

“It feels kind of like an extra force moving with you,” says Ballesteros, who also tried out the suit and arm assist. “Imagine wearing a backpack and someone grabs the top and sort of pulls you up. Over time, it becomes sort of natural.”

The experiments confirmed that the control system can successfully direct a robot to help a person stand back up after a fall. The researchers plan to pair the control system with their latest version of SuperLimbs, which comprises two multijointed robotic arms that can extend out from a backpack. The backpack would also contain the robot’s battery and motors, along with an astronaut’s ventilation system.

“We designed these robotic arms based on an AI search and design optimization, to look for designs of classic robot manipulators with certain engineering constraints,” Ballesteros says. “We filtered through many designs and looked for the design that consumes the least amount of energy to lift a person up. This version of SuperLimbs is the product of that process.”

Over the summer, Ballesteros will build out the full SuperLimbs system at NASA’s Jet Propulsion Laboratory, where he plans to streamline the design and minimize the weight of its parts and motors using advanced, lightweight materials. Then, he hopes to pair the limbs with astronaut suits, and test them in low-gravity simulators, with the goal of someday assisting astronauts on future missions to the moon and Mars.

“Wearing a spacesuit can be a physical burden,” Asada notes. “Robotic systems can help ease that burden, and help astronauts be more productive during their missions.”

This research was supported, in part, by NASA.



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MIT’s Master of Applied Science in Data, Economics, and Design of Policy program adds a public policy track

MIT’s Abdul Latif Jameel Poverty Action Lab (J-PAL) and Department of Economics have announced an expansion of their jointly administered Master of Applied Science in Data, Economics, and Design of Policy (DEDP) program. This expansion adds a new public policy track to complement the existing international development track, opening up new avenues for student learning and research. 

Designed to tackle poverty alleviation and other pressing policy challenges in the United States and other high-income countries, the curriculum of the new track spans a diverse set of issues, from domestic concerns like minimum wage and consumer welfare to global matters including trade, climate change, and immigration. Applications for the public policy track will open this fall, with the inaugural cohort set to arrive on MIT’s campus in spring 2026.

The DEDP program, led by MIT professors and Nobel laureates Abhijit Banerjee and Esther Duflo, along with professors Sara Fisher Ellison and Benjamin Olken, was established with the mission of equipping diverse cohorts of talented professionals with the knowledge and skills to tackle poverty using evidence-based approaches. The new master’s degree track will support this mission while also underscoring the program’s commitment to addressing a broad array of critical challenges in the fight against poverty worldwide.

"The DEDP program has proven successful on many dimensions, and we are enthusiastic about leveraging its successes to address a broader set of social challenges,” says Ellison, a faculty lead for the program. “The public policy track will enable us to apply evidence-based methodology to poverty alleviation and other related issues in the context of high-income countries, as well. Given increasing levels of wealth and income inequality in these countries, we feel that the timing is opportune and the need is great."

The DEDP program distinguishes itself with an innovative admissions model that prioritizes demonstrated ability and motivation over traditional credentials, such as standardized tests and recommendation letters. To be eligible to apply to the master’s program, candidates must have earned a DEDP MicroMasters credential by passing five of the DEDP online courses. The courses are completely free to audit. Those who wish to earn a course certificate can pay a fee, which varies by the learner’s ability to pay, to take the proctored exam. While applications are reviewed holistically, performance in these classes is the primary factor in admissions decisions.

This approach democratizes access to higher education, enabling students from typically underrepresented backgrounds to demonstrate their potential for success. Notably, the program has welcomed many students from nontraditional backgrounds, such as a student who enrolled directly from high school (and who is now a second-year PhD student in economics at MIT), reflecting the ambition of its faculty directors to make higher education more accessible.

Sofia Martinez, a graduate of the class of 2023 and now co-founder of Learning Alliance, says, "Without the MicroMasters paving the way, applying to MIT or any similar institution would have been unthinkable for us. Initially, my aim in taking the online courses wasn't to pursue the residential program; it was only after witnessing my own progress that I realized the possibility wasn't so distant after all. This sentiment resonates with many in our cohort, which is truly humbling.”

Since its launch in 2020, the DEDP master’s program has conferred degrees to 87 students from 44 countries, showcasing its global reach and the success of its admissions model. Upon arriving on campus, students embark on an accelerated master's program. They complete a full course load in the spring, followed by a capstone project in the summer, applying the theoretical knowledge and practical skills gained through the program at research and policy organizations.



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Astronomers spot a giant planet that is as light as cotton candy

Astronomers at MIT, the University of Liège in Belgium, and elsewhere have discovered a huge, fluffy oddball of a planet orbiting a distant star in our Milky Way galaxy. The discovery, reported today in the journal Nature Astronomy, is a promising key to the mystery of how such giant, super-light planets form.

The new planet, named WASP-193b, appears to dwarf Jupiter in size, yet it is a fraction of its density. The scientists found that the gas giant is 50 percent bigger than Jupiter, and about a tenth as dense — an extremely low density, comparable to that of cotton candy.

WASP-193b is the second lightest planet discovered to date, after the smaller, Neptune-like world, Kepler 51d. The new planet’s much larger size, combined with its super-light density, make WASP-193b something of an oddity among the more than 5,400 planets discovered to date.

“To find these giant objects with such a small density is really, really rare,” says lead study author and MIT postdoc Khalid Barkaoui. “There’s a class of planets called puffy Jupiters, and it’s been a mystery for 15 years now as to what they are. And this is an extreme case of that class.”

“We don’t know where to put this planet in all the formation theories we have right now, because it’s an outlier of all of them,” adds co-lead author Francisco Pozuelos, a senior researcher at the Institute of Astrophysics of Andalucia, in Spain. “We cannot explain how this planet was formed, based on classical evolution models. Looking more closely at its atmosphere will allow us to obtain an evolutionary path of this planet.”

The study’s MIT co-authors include Julien de Wit, an assistant professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences, and MIT postdoc Artem Burdanov, along with collaborators from multiple institutions across Europe.

“An interesting twist”

The new planet was initially spotted by the Wide Angle Search for Planets, or WASP — an international collaboration of academic institutions that together operate two robotic observatories, one in the northern hemisphere and the other in the south. Each observatory uses an array of wide-angle cameras to measure the brightness of thousands of individual stars across the entire sky.

In surveys taken between 2006 and 2008, and again from 2011 to 2012, the WASP-South observatory detected periodic transits, or dips in light, from WASP-193 — a bright, nearby, sun-like star located 1,232 light years from Earth. Astronomers determined that the star’s periodic dips in brightness were consistent with a planet circling the star and blocking its light every 6.25 days. The scientists measured the total amount of light the planet blocked with each transit, which gave them an estimate of the planet’s giant, super-Jupiter size.

The astronomers then looked to pin down the planet’s mass — a measure that would then reveal its density and potentially also clues to its composition. To get a mass estimate, astronomers typically employ radial velocity, a technique in which scientists analyze a star’s spectrum, or various wavelengths of light, as a planet circles the star. A star’s spectrum can be shifted in specific ways depending on whatever is pulling on the star, such as an orbiting planet. The more massive a planet is, and the closer it is to its star, the more its spectrum can shift — a distortion that can give scientists an idea of a planet’s mass.

For WASP-193 b, astronomers obtained additional high-resolution spectra of the star taken by various ground-based telescopes, and attempted to employ radial velocity to calculate the planet’s mass. But they kept coming up empty — precisely because, as it turned out, the planet was far too light to have any detectable pull on its star.

“Typically, big planets are pretty easy to detect because they are usually massive, and lead to a big pull on their star,” de Wit explains. “But what was tricky about this planet was, even though it’s big — huge — its mass and density are so low that it was actually very difficult to detect with just the radial velocity technique. It was an interesting twist.”

“[WASP-193b] is so very light that it took four years to gather data and show that there is a mass signal, but it’s really, really tiny,” Barkaoui says.

“We were initially getting extremely low densities, which were very difficult to believe in the beginning,” Pozuelos adds. “We repeated the process of all the data analysis several times to make sure this was the real density of the planet because this was super rare.”

An inflated world

In the end, the team confirmed that the planet was indeed extremely light. Its mass, they calculated, was about 0.14 that of Jupiter. And its density, derived from its mass, came out to about 0.059 grams per cubic centimeter. Jupiter, in contrast, is about 1.33 grams per cubic centimeter; and Earth is a more substantial 5.51 grams per cubic centimeter. Perhaps the material closest in density to the new, puffy planet is cotton candy, which has a density of about 0.05 grams per cubic centimeter.

“The planet is so light that it’s difficult to think of an analogous, solid-state material,” Barkaoui says. “The reason why it’s close to cotton candy is because both are mostly made of light gases rather than solids. The planet is basically super fluffy.”

The researchers suspect that the new planet is made mostly from hydrogen and helium, like most other gas giants in the galaxy. For WASP-193b, these gases likely form a hugely inflated atmosphere that extends tens of thousands of kilometers farther than Jupiter’s own atmosphere. Exactly how a planet can inflate so far while maintaining a super-light density is a question that no existing theory of planetary formation can yet answer.

To get a better picture of the new fluffy world, the team plans to use a technique de Wit previously developed, to first derive certain properties of the planet’s atmosphere, such as its temperature, composition, and pressure at various depths. These characteristics can then be used to precisely work out the planet’s mass. For now, the team sees WASP-193b as an ideal candidate for follow-up study by observatories such as the James Webb Space Telescope.

“The bigger a planet’s atmosphere, the more light can go through,” de Wit says. “So it’s clear that this planet is one of the best targets we have for studying atmospheric effects. It will be a Rosetta Stone to try and resolve the mystery of puffy Jupiters.”

This research was funded, in part, by consortium universities and the UK’s Science and Technology Facilities Council for WASP; the European Research Council; the Wallonia-Brussels Federation; and the Heising-Simons Foundation, Colin and Leslie Masson, and Peter A. Gilman, supporting Artemis and the other SPECULOOS Telescopes.



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Scientists develop an affordable sensor for lead contamination

Engineers at MIT, Nanytang Technological University, and several companies have developed a compact and inexpensive technology for detecting and measuring lead concentrations in water, potentially enabling a significant advance in tackling this persistent global health issue.

The World Health Organization estimates that 240 million people worldwide are exposed to drinking water that contains unsafe amounts of toxic lead, which can affect brain development in children, cause birth defects, and produce a variety of neurological, cardiac, and other damaging effects. In the United States alone, an estimated 10 million households still get drinking water delivered through lead pipes.

“It’s an unaddressed public health crisis that leads to over 1 million deaths annually,” says Jia Xu Brian Sia, an MIT postdoc and the senior author of the paper describing the new technology.

But testing for lead in water requires expensive, cumbersome equipment and typically requires days to get results. Or, it uses simple test strips that simply reveal a yes-or-no answer about the presence of lead but no information about its concentration. Current EPA regulations require drinking water to contain no more that 15 parts per billion of lead, a concentration so low it is difficult to detect.

The new system, which could be ready for commercial deployment within two or three years, could detect lead concentrations as low as 1 part per billion, with high accuracy, using a simple chip-based detector housed in a handheld device. The technology gives nearly instant quantitative measurements and requires just a droplet of water.

The findings are described in a paper appearing today in the journal Nature Communications, by Sia, MIT graduate student and lead author Luigi Ranno, Professor Juejun Hu, and 12 others at MIT and other institutions in academia and industry.

The team set out to find a simple detection method based on the use of photonic chips, which use light to perform measurements. The challenging part was finding a way to attach to the photonic chip surface certain ring-shaped molecules known as crown ethers, which can capture specific ions such as lead. After years of effort, they were able to achieve that attachment via a chemical process known as Fischer esterification. “That is one of the essential breakthroughs we have made in this technology,” Sia says.

In testing the new chip, the researchers showed that it can detect lead in water at concentrations as low as one part per billion. At much higher concentrations, which may be relevant for testing environmental contamination such as mine tailings, the accuracy is within 4 percent.

The device works in water with varying levels of acidity, ranging from pH values of 6 to 8, “which covers most environmental samples,” Sia says. They have tested the device with seawater as well as tap water, and verified the accuracy of the measurements.

In order to achieve such levels of accuracy, current testing requires a device called an inductive coupled plasma mass spectrometer. “These setups can be big and expensive,” Sia says. The sample processing can take days and requires experienced technical personnel.

While the new chip system they developed is “the core part of the innovation,” Ranno says, further work will be needed to develop this into an integrated, handheld device for practical use. “For making an actual product, you would need to package it into a usable form factor,” he explains. This would involve having a small chip-based laser coupled to the photonic chip. “It’s a matter of mechanical design, some optical design, some chemistry, and figuring out the supply chain,” he says. While that takes time, he says, the underlying concepts are straightforward.

The system can be adapted to detect other similar contaminants in water, including cadmium, copper, lithium, barium, cesium, and radium, Ranno says. The device could be used with simple cartridges that can be swapped out to detect different elements, each using slightly different crown ethers that can bind to a specific ion.

“There’s this problem that people don’t measure their water enough, especially in the developing countries,” Ranno says. “And that’s because they need to collect the water, prepare the sample, and bring it to these huge instruments that are extremely expensive.” Instead, “having this handheld device, something compact that even untrained personnel can just bring to the source for on-site monitoring, at low costs,” could make regular, ongoing widespread testing feasible.

Hu, who is the John F. Elliott Professor of Materials Science and Engineering, says, “I’m hoping this will be quickly implemented, so we can benefit human society. This is a good example of a technology coming from a lab innovation where it may actually make a very tangible impact on society, which is of course very fulfilling.”

“If this study can be extended to simultaneous detection of multiple metal elements, especially the presently concerning radioactive elements, its potential would be immense,” says Hou Wang, an associate professor of environmental science and engineering at Hunan University in China, who was not associated with this work.

Wang adds, “This research has engineered a sensor capable of instantaneously detecting lead concentration in water. This can be utilized in real-time to monitor the lead pollution concentration in wastewater discharged from industries such as battery manufacturing and lead smelting, facilitating the establishment of industrial wastewater monitoring systems. I think the innovative aspects and developmental potential of this research are quite commendable.”

Wang Qian, a principal research scientist at the Institute of Materials Research in Singapore, who also was not affiliated with this work, says, “The ability for the pervasive, portable, and quantitative detection of lead has proved to be challenging primarily due to cost concerns. This work demonstrates the potential to do so in a highly integrated form factor and is compatible with large-scale, low-cost manufacturing.”

The team included researchers at MIT, at Nanyang Technological University and Temasek Laboratories in Singapore, at the University of Southampton in the U.K., and at companies Fingate Technologies, in Singapore, and Vulcan Photonics, headquartered in Malaysia. The work used facilities at MIT.nano, the Harvard University Center for Nanoscale Systems, NTU’s Center for Micro- and Nano-Electronics, and the Nanyang Nanofabrication Center.



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lunes, 13 de mayo de 2024

MIT researchers discover the universe’s oldest stars in our own galactic backyard

MIT researchers, including several undergraduate students, have discovered three of the oldest stars in the universe, and they happen to live in our own galactic neighborhood.

The team spotted the stars in the Milky Way’s “halo” — the cloud of stars that envelopes the entire main galactic disk. Based on the team’s analysis, the three stars formed between 12 and 13 billion years ago, the time when the very first galaxies were taking shape.

The researchers have coined the stars “SASS,” for Small Accreted Stellar System stars, as they believe each star once belonged to its own small, primitive galaxy that was later absorbed by the larger but still growing Milky Way. Today, the three stars are all that are left of their respective galaxies. They circle the outskirts of the Milky Way, where the team suspects there may be more such ancient stellar survivors.

“These oldest stars should definitely be there, given what we know of galaxy formation,” says MIT professor of physics Anna Frebel. “They are part of our cosmic family tree. And we now have a new way to find them.”

As they uncover similar SASS stars, the researchers hope to use them as analogs of ultrafaint dwarf galaxies, which are thought to be some of the universe’s surviving first galaxies. Such galaxies are still intact today but are too distant and faint for astronomers to study in depth. As SASS stars may have once belonged to similarly primitive dwarf galaxies but are in the Milky Way and as such much closer, they could be an accessible key to understanding the evolution of ultrafaint dwarf galaxies.

“Now we can look for more analogs in the Milky Way, that are much brighter, and study their chemical evolution without having to chase these extremely faint stars,” Frebel says.

She and her colleagues have published their findings today in the Monthly Notices of the Royal Astronomical Society (MNRAS). The study’s co-authors are Mohammad Mardini, at Zarqa University, in Jordan; Hillary Andales ’23; and current MIT undergraduates Ananda Santos and Casey Fienberg.

Stellar frontier

The team’s discoveries grew out of a classroom concept. During the 2022 fall semester, Frebel launched a new course, 8.S30 (Observational Stellar Archaeology), in which students learned techniques for analyzing ancient stars and then applied those tools to stars that had never been studied before, to determine their origins.

“While most of our classes are taught from the ground up, this class immediately put us at the frontier of research in astrophysics,” Andales says.

The students worked from star data collected by Frebel over the years from the 6.5-meter Magellan-Clay telescope at the Las Campanas Observatory. She keeps hard copies of the data in a large binder in her office, which the students combed through to look for stars of interest.

In particular, they were searching ancient stars that formed soon after the Big Bang, which occurred 13.8 billion years ago. At this time, the universe was made mostly of hydrogen and helium and very low abundances of other chemical elements, such as strontium and barium. So, the students looked through Frebel’s binder for stars with spectra, or measurements of starlight, that indicated low abundances of strontium and barium.

Their search narrowed in on three stars that were originally observed by the Magellan telescope between 2013 and 2014. Astronomers never followed up on these particular stars to interpret their spectra and deduce their origins. They were, then, perfect candidates for the students in Frebel’s class.

The students learned how to characterize a star in order to prepare for the analysis of the spectra for each of the three stars. They were able to determine the chemical composition of each one with various stellar models. The intensity of a particular feature in the stellar spectrum, corresponding to a specific wavelength of light, corresponds to a particular abundance of a specific element.

After finalizing their analysis, the students were able to confidently conclude that the three stars did hold very low abundances of strontium, barium, and other elements such as iron, compared to their reference star — our own sun. In fact, one star contained less than 1/10,000 the amount of iron to helium compared to the sun today.

“It took a lot of hours staring at a computer, and a lot of debugging, frantically texting and emailing each other to figure this out,” Santos recalls. “It was a big learning curve, and a special experience.”

“On the run”

The stars’ low chemical abundance did hint that they originally formed 12 to 13 billion years ago. In fact, their low chemical signatures were similar to what astronomers had previously measured for some ancient, ultrafaint dwarf galaxies. Did the team’s stars originate in similar galaxies? And how did they come to be in the Milky Way?

On a hunch, the scientists checked out the stars’ orbital patterns and how they move across the sky. The three stars are in different locations throughout the Milky Way’s halo and are estimated to be about 30,000 light years from Earth. (For reference, the disk of the Milky Way spans 100,000 light years across.)

As they retraced each star’s motion about the galactic center using observations from the Gaia astrometric satellite, the team noticed a curious thing: Relative to most of the stars in the main disk, which move like cars on a racetrack, all three stars seemed to be going the wrong way. In astronomy, this is known as “retrograde motion” and is a tipoff that an object was once “accreted,” or drawn in from elsewhere.

“The only way you can have stars going the wrong way from the rest of the gang is if you threw them in the wrong way,” Frebel says.

The fact that these three stars were orbiting in completely different ways from the rest of the galactic disk and even the halo, combined with the fact that they held low chemical abundances, made a strong case that the stars were indeed ancient and once belonged to older, smaller dwarf galaxies that fell into the Milky Way at random angles and continued their stubborn trajectories billions of years later.

Frebel, curious as to whether retrograde motion was a feature of other ancient stars in the halo that astronomers previously analyzed, looked through the scientific literature and found 65 other stars, also with low strontium and barium abundances, that appeared to also be going against the galactic flow.

“Interestingly they’re all quite fast — hundreds of kilometers per second, going the wrong way,” Frebel says. “They’re on the run! We don’t know why that’s the case, but it was the piece to the puzzle that we needed, and that I didn’t quite anticipate when we started.”

The team is eager to search out other ancient SASS stars, and they now have a relatively simple recipe to do so: First, look for stars with low chemical abundances, and then track their orbital patterns for signs of retrograde motion. Of the more than 400 billion stars in the Milky Way, they anticipate that the method will turn up a small but significant number of the universe’s oldest stars.

Frebel plans to relaunch the class this fall, and looks back at that first course, and the three students who took their results through to publication, with admiration and gratitude.

“It’s been awesome to work with three women undergrads. That’s a first for me,” she says. “It’s really an example of the MIT way. We do. And whoever says, ‘I want to participate,’ they can do that, and good things happen.”

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



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Four from MIT named 2024 Knight-Hennessy Scholars

MIT senior Owen Dugan, graduate student Vittorio Colicci ’22, predoctoral research fellow Carine You ’22, and recent alumna Carina Letong Hong ’22 are recipients of this year’s Knight-Hennessy Scholarships. The competitive fellowship, now in its seventh year, funds up to three years of graduate studies in any field at Stanford University. To date, 22 MIT students and alumni have been awarded Knight-Hennessy Scholarships.

“We are excited for these students to continue their education at Stanford with the generous support of the Knight Hennessy Scholarship,” says Kim Benard, associate dean of distinguished fellowships in Career Advising and Professional Development. “They have all demonstrated extraordinary dedication, intellect, and leadership, and this opportunity will allow them to further hone their skills to make real-world change.”

Vittorio Colicci ’22

Vittorio Colicci, from Trumbull, Connecticut, graduated from MIT in May 2022 with a BS in aerospace engineering and physics. He will receive his master’s degree in planetary sciences this spring. At Stanford, Colicci will pursue a PhD in earth and planetary sciences at the Stanford Doerr School of Sustainability. He hopes to investigate how surface processes on Earth and Mars have evolved through time alongside changes in habitability. Colicci has worked largely on spacecraft engineering projects, developing a monodisperse silica ceramic for electrospray thrusters and fabricating high-energy diffraction gratings for space telescopes. As a Presidential Graduate Fellow at MIT, he examined the influence of root geometry on soil cohesion for early terrestrial plants using 3D-printed reconstructions. Outside of research, Colicci served as co-director of TEDxMIT and propulsion lead for the MIT Rocket Team. He is also passionate about STEM engagement and outreach, having taught educational workshops in Zambia and India.

Owen Dugan

Owen Dugan, from Sleepy Hollow, New York, is a senior majoring in physics. As a Knight-Hennessy Scholar, he will pursue a PhD in computer science at the Stanford School of Engineering. Dugan aspires to combine artificial intelligence and physics, developing AI that enables breakthroughs in physics and using physics techniques to design more capable and safe AI systems. He has collaborated with researchers from Harvard University, the University of Chicago, and DeepMind, and has presented his first-author research at venues including the International Conference on Machine Learning, the MIT Mechanistic Interpretability Conference, and the American Physical Society March Meeting. Among other awards, Dugan is a Hertz Finalist, a U.S. Presidential Scholar, an MIT Outstanding Undergraduate Research Awardee, a Research Science Institute Scholar, and a Neo Scholar. He is also a co-founder of VeriLens, a funded startup enabling trust on the internet by cryptographically verifying digital media.

Carina Letong Hong ’22

Carina Letong Hong, from Canton, China, is currently pursuing a JD/PhD in mathematics at Stanford. A first-generation college student, Hong graduated from MIT in May 2022 with a double major in mathematics and physics and was inducted into Sigma Pi Sigma, the physics honor society. She then earned a neuroscience master’s degree with dissertation distinctions from the University of Oxford, where she conducted artificial intelligence and machine learning research at Sainsbury Wellcome Center’s Gatsby Unit. At Stanford Law School, Hong provides legal aid to low-income workers and uses economic analysis to push for law enforcement reform. She has published numerous papers in peer-reviewed journals, served as an expert referee for journals and conferences, and spoken at summits in the United States, Germany, France, the U.K., and China. She was the recipient of the AMS-MAA-SIAM Morgan Prize for Outstanding Research, the highest honor for an undergraduate in mathematics in North America; the AWM Alice T. Schafer Prize for Mathematical Excellence, given annually to an undergraduate woman in the United States; the Maryam Mirzakhani Fellowship; and a Rhodes Scholarship.

Carine You ’22

Carine You, from San Diego, California, graduated from MIT in May 2022 with bachelor’s degrees in electrical engineering and computer science and in mathematics. Since graduating, You has worked as a predoctoral research assistant with Professor Amy Finkelstein in the MIT Department of Economics, where she has studied the quality of Medicare nursing home care and the targeting of medical screening technologies. This fall, You will embark on a PhD in economic analysis and policy at the Stanford Graduate School of Business. She wishes to address pressing issues in environmental and health-care markets, with a particular focus on economic efficiency and equity. You previously developed audio signal processing algorithms at Bose, refined mechanistic models to inform respiratory monitoring at the MIT Research Laboratory of Electronics, and analyzed corruption in developmental projects in India at the World Bank. Through Middle East Entrepreneurs of Tomorrow, she taught computer science to Israeli and Palestinian students in Jerusalem and spearheaded an online pilot expansion for the organization. At MIT, she was named a Burchard Scholar.



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Taking RNAi from interesting science to impactful new treatments

There are many hurdles to clear before a research discovery becomes a life-changing treatment for patients. That’s especially true when the treatments being developed represent an entirely new class of medicines. But overcoming those obstacles can revolutionize our ability to treat diseases.

Few companies exemplify that process better than Alnylam Pharmaceuticals. Alnylam was founded by a group of MIT-affiliated researchers who believed in the promise of a technology — RNA interference, or RNAi.

The researchers had done foundational work to understand how RNAi, which is a naturally occurring process, works to silence genes through the degradation of messenger RNA. But it was their decision to found Alnylam in 2002 that attracted the funding and expertise necessary to turn their discoveries into a new class of medicines. Since that decision, Alnylam has made remarkable progress taking RNAi from an interesting scientific discovery to an impactful new treatment pathway.

Today Alnylam has five medicines approved by the U.S. Food and Drug Administration (one Alnylam-discovered RNAi therapeutic is licensed to Novartis) and a rapidly expanding clinical pipeline. The company’s approved medicines are for debilitating, sometimes fatal conditions that many patients have grappled with for decades with few other options.

The company estimates its treatments helped more than 5,000 patients in 2023 alone. Behind that number are patient stories that illustrate how Alnylam has changed lives. A mother of three says Alnylam’s treatments helped her take back control of her life after being bed-ridden with attacks associated with the rare genetic disease acute intermittent porphyria (AIP). Another patient reported that one of the company’s treatments helped her attend her daughter’s wedding. A third patient, who had left college due to frequent AIP attacks, was able to return to school.

These days Alnylam is not the only company developing RNAi-based medicines. But it is still a pioneer in the field, and the company’s founders — MIT Institute Professor Phil Sharp, Professor David Bartel, Professor Emeritus Paul Schimmel, and former MIT postdocs Thomas Tuschl and Phillip Zamore — see Alnylam as a champion for the field more broadly.

“Alnylam has published more than 250 scientific papers over 20 years,” says Sharp, who currently serves as chair of Alnylam’s scientific advisory board. “Not only did we do the science, not only did we translate it to benefit patients, but we also described every step. We established this as a modality to treat patients, and I’m very proud of that record.”

Pioneering RNAi development

MIT’s involvement in RNAi dates back to its discovery. Before Andrew Fire PhD ’83 shared a Nobel Prize for the discovery of RNAi in 1998, he worked on understanding how DNA was transcribed into RNA, as a graduate student in Sharp’s lab.

After leaving MIT, Fire and collaborators showed that double-stranded RNA could be used to silence specific genes in worms. But the biochemical mechanisms that allowed double-stranded RNA to work were unknown until MIT professors Sharp, Bartel, and Ruth Lehmann, along with Zamore and Tuschl, published foundational papers explaining the process. The researchers developed a system for studying RNAi and showed how RNAi can be controlled using different genetic sequences. Soon after Tuschl left MIT, he showed that a similar process could also be used to silence specific genes in human cells, opening up a new frontier in studying genes and ultimately treating diseases.

“Tom showed you could synthesize these small RNAs, transfect them into cells, and get a very specific knockdown of the gene that corresponded to that the small RNAs,” Bartel explains. “That discovery transformed biological research. The ability to specifically knockdown a mammalian gene was huge. You could suddenly study the function of any gene you were interested in by knocking it down and seeing what happens. … The research community immediately started using that approach to study the function of their favorite genes in mammalian cells.”

Beyond illuminating gene function, another application came to mind.

“Because almost all diseases are related to genes, could we take these small RNAs and silence genes to treat patients?” Sharp remembers wondering.

To answer the question, the researchers founded Alnylam in 2002. (They recruited Schimmel, a biotech veteran, around the same time.) But there was a lot of work to be done before the technology could be tried in patients. The main challenge was getting RNAi into the cytoplasm of the patients’ cells.

“Through work in Dave Bartel and Phil Sharp's lab, among others, it became evident that to make RNAi into therapies, there were three problems to solve: delivery, delivery, and delivery,” says Alnylam Chief Scientific Officer Kevin Fitzgerald, who has been with the company since 2005.

Early on, Alnylam collaborated with MIT drug delivery expert and Institute Professor Bob Langer. Eventually, Alnylam developed the first lipid nanoparticles (LNPs) that could be used to encase RNA and deliver it into patient cells. LNPs were later used in the mRNA vaccines for Covid-19.

“Alnylam has invested over 20 years and more than $4 billion in RNAi to develop these new therapeutics,” Sharp says. “That is the means by which innovations can be translated to the benefit of society.”

From scientific breakthrough to patient bedside

Alnylam received its first FDA approval in 2018 for treatment of the polyneuropathy of hereditary transthyretin-mediated amyloidosis, a rare and fatal disease. It doubled as the first RNAi therapeutic to reach the market and the first drug approved to treat that condition in the United States.

“What I keep in mind is, at the end of the day for certain patients, two months is everything,” Fitzgerald says. “The diseases that we’re trying to treat progress month by month, day by day, and patients can get to a point where nothing is helping them. If you can move their disease by a stage, that’s huge.”

Since that first treatment, Alnylam has updated its RNAi delivery system — including by conjugating small interfering RNAs to molecules that help them gain entry to cells — and earned approvals to treat other rare genetic diseases along with high cholesterol (the treatment licensed to Novartis). All of those treatments primarily work by silencing genes that encode for the production of proteins in the liver, which has proven to be the easiest place to deliver RNAi molecules. But Alnylam’s team is confident they can deliver RNAi to other areas of the body, which would unlock a new world of treatment possibilities. The company has reported promising early results in the central nervous system and says a phase one study last year was the first RNAi therapeutic to demonstrate gene silencing in the human brain.

“There’s a lot of work being done at Alnylam and other companies to deliver these RNAis to other tissues: muscles, immune cells, lung cells, etc.,” Sharp says. “But to me the most interesting application is delivery to the brain. We think we have a therapeutic modality that can very specifically control the activity of certain genes in the nervous system. I think that’s extraordinarily important, for diseases from Alzheimer’s to schizophrenia and depression.”

The central nervous system work is particularly significant for Fitzgerald, who watched his father struggle with Parkinson’s.

“Our goal is to be in every organ in the human body, and then combinations of organs, and then combinations of targets within individual organs, and then combinations of targets within multi-organs,” Fitzgerald says. “We’re really at the very beginning of what this technology is going do for human health.”

It’s an exciting time for the RNAi scientific community, including many who continue to study it at MIT. Still, Alnylam will need to continue executing in its drug development efforts to deliver on that promise and help an expanding pool of patients.

“I think this is a real frontier,” Sharp says. “There’s major therapeutic need, and I think this technology could have a huge impact. But we have to prove it. That’s why Alnylam exists: to pursue new science that unlocks new possibilities and discover if they can be made to work. That, of course, also why MIT is here: to improve lives.”



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viernes, 10 de mayo de 2024

The power of App Inventor: Democratizing possibilities for mobile applications

In June 2007, Apple unveiled the first iPhone. But the company made a strategic decision about iPhone software: its new App Store would be a walled garden. An iPhone user wouldn’t be able to install applications that Apple itself hadn’t vetted, at least not without breaking Apple’s terms of service.

That business decision, however, left educators out in the cold. They had no way to bring mobile software development — about to become part of everyday life — into the classroom. How could a young student code, futz with, and share apps if they couldn’t get it into the App Store?

MIT professor Hal Abelson was on sabbatical at Google at the time, when the company was deciding how to respond to Apple’s gambit to corner the mobile hardware and software market. Abelson recognized the restrictions Apple was placing on young developers; Google recognized the market need for an open-source alternative operating system — what became Android. Both saw the opportunity that became App Inventor.

“Google started the Android project sort of in reaction to the iPhone,” Abelson says. “And I was there, looking at what we did at MIT with education-focused software like Logo and Scratch, and said ‘what a cool thing it would be if kids could make mobile apps also.’”

Google software engineer Mark Friedman volunteered to work with Abelson on what became “Young Android,” soon renamed Google App Inventor. Like Scratch, App Inventor is a block-based language, allowing programmers to visually snap together pre-made “blocks” of code rather than need to learn specialized programming syntax.

Friedman describes it as novel for the time, particularly for mobile development, to make it as easy as possible to build simple mobile apps. “That meant a web-based app,” he says, “where everything was online and no external tools were required, with a simple programming model, drag-and-drop user interface designing, and blocks-based visual programming.” Thus an app someone programmed in a web interface could be installed on an Android device.

App Inventor scratched an itch. Boosted by the explosion in smartphone adoption and the fact App Inventor is free (and eventually open source), soon more than 70,000 teachers were using it with hundreds of thousands of students, with Google providing the backend infrastructure to keep it going.

“I remember answering a question from my manager at Google who asked how many users I thought we'd get in the first year,” Friedman says. “I thought it would be about 15,000 — and I remember thinking that might be too optimistic. I was ultimately off by a factor of 10–20.” Friedman was quick to credit more than their choices about the app. “I think that it's fair to say that while some of that growth was due to the quality of the tool, I don't think you can discount the effect of it being from Google and of the effect of Hal Abelson's reputation and network.”

Some early apps took App Inventor in ambitious, unexpected directions, such as “Discardious,” developed by teenage girls in Nigeria. Discardious helped business owners and individuals dispose of waste in communities where disposal was unreliable or too cumbersome.

But even before apps like Discardious came along, the team knew Google’s support wouldn’t be open-ended. No one wanted to cut teachers off from a tool they were thriving with, so around 2010, Google and Abelson agreed to transfer App Inventor to MIT. The transition meant major staff contributions to recreate App Inventor without Google’s proprietary software but MIT needing to work with Google to continue to provide the network resources to keep App Inventor free for the world.

With such a large user base, however, that left Abelson “worried the whole thing was going to collapse” without Google’s direct participation.

Friedman agrees. “I would have to say that I had my fears. App Inventor has a pretty complicated technical implementation, involving multiple programming languages, libraries and frameworks, and by the end of its time at Google we had a team of about 10 people working on it.”

Yet not only did Google provide significant funding to aid the transfer, but, Friedman says of the transfer’s ultimate success, “Hal would be in charge and he had fairly extensive knowledge of the system and, of course, had great passion for the vision and the product.”

MIT enterprise architect Jeffrey Schiller, who built the Institute’s computer network and became its manager in 1984, was another key part in sustaining App Inventor after its transition, helping introduce technical features fundamental to its accessibility and long-term success. He led the integration of the platform into web browsers, the addition of WiFi support rather than needing to connect phones and computers via USB, and the laying of groundwork for technical support of older phones because, as Schiller says, “many of our users cannot rush out and purchase the latest and most expensive devices.”

These collaborations and contributions over time resulted in App Inventor’s greatest resource: its user base. As it grew, and with support from community managers, volunteer know-how grew with it. Now, more than a decade since its launch, App Inventor recently crossed several major milestones, the most remarkable being the creation of its 100 millionth project and registration of its 20 millionth user. Young developers continue to make incredible applications, boosted now by the advantages of AI. College students created “Brazilian XôDengue” as a way for users to use phone cameras to identify mosquito larvae that may be carrying the dengue virus. High school students recently developed “Calmify,” a journaling app that uses AI for emotion detection. And a mother in Kuwait wanted something to help manage the often-overwhelming experience of new motherhood when returning to work, so she built the chatbot “PAM (Personal Advisor to Mothers)” as a non-judgmental space to talk through the challenges.

App Inventor’s long-term sustainability now rests with the App Inventor Foundation, created in 2022 to grow its resources and further drive its adoption. It is led by executive director Natalie Lao.

In a letter to the App Inventor community, Lao highlighted the foundation’s commitment to equitable access to educational resources, which for App Inventor required a rapid shift toward AI education — but in a way that upholds App Inventor’s core values to be “a free, open-source, easy-to-use platform” for mobile devices. “Our mission is to not only democratize access to technology,” Lao wrote, “but also foster a culture of innovation and digital literacy.”

Within MIT, App Inventor today falls under the umbrella of the MIT RAISE Initiative — Responsible AI for Social Empowerment and Education, run by Dean for Digital Learning Cynthia Breazeal, Professor Eric Klopfer, and Abelson. Together they are able to integrate App Inventor into ever-broader communities, events, and funding streams, leading to opportunities like this summer’s inaugural AI and Education Summit on July 24-26. The summit will include awards for winners of a Global AI Hackathon, whose roughly 180 submissions used App Inventor to create AI tools in two tracks: Climate & Sustainability and Health & Wellness. Tying together another of RAISE’s major projects, participants were encouraged to draw from Day of AI curricula, including its newest courses on data science and climate change.

“Over the past year, there's been an enormous mushrooming in the possibilities for mobile apps through the integration of AI,” says Abelson. “The opportunity for App Inventor and MIT is to democratize those new possibilities for young people — and for everyone — as an enhanced source of power and creativity.”



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Using MRI, engineers have found a way to detect light deep in the brain

Scientists often label cells with proteins that glow, allowing them to track the growth of a tumor, or measure changes in gene expression that occur as cells differentiate.

While this technique works well in cells and some tissues of the body, it has been difficult to apply this technique to image structures deep within the brain, because the light scatters too much before it can be detected.

MIT engineers have now come up with a novel way to detect this type of light, known as bioluminescence, in the brain: They engineered blood vessels of the brain to express a protein that causes them to dilate in the presence of light. That dilation can then be observed with magnetic resonance imaging (MRI), allowing researchers to pinpoint the source of light.

“A well-known problem that we face in neuroscience, as well as other fields, is that it’s very difficult to use optical tools in deep tissue. One of the core objectives of our study was to come up with a way to image bioluminescent molecules in deep tissue with reasonably high resolution,” says Alan Jasanoff, an MIT professor of biological engineering, brain and cognitive sciences, and nuclear science and engineering.

The new technique developed by Jasanoff and his colleagues could enable researchers to explore the inner workings of the brain in more detail than has previously been possible.

Jasanoff, who is also an associate investigator at MIT’s McGovern Institute for Brain Research, is the senior author of the study, which appears today in Nature Biomedical Engineering. Former MIT postdocs Robert Ohlendorf and Nan Li are the lead authors of the paper.

Detecting light

Bioluminescent proteins are found in many organisms, including jellyfish and fireflies. Scientists use these proteins to label specific proteins or cells, whose glow can be detected by a luminometer. One of the proteins often used for this purpose is luciferase, which comes in a variety of forms that glow in different colors.

Jasanoff’s lab, which specializes in developing new ways to image the brain using MRI, wanted to find a way to detect luciferase deep within the brain. To achieve that, they came up with a method for transforming the blood vessels of the brain into light detectors. A popular form of MRI works by imaging changes in blood flow in the brain, so the researchers engineered the blood vessels themselves to respond to light by dilating.

“Blood vessels are a dominant source of imaging contrast in functional MRI and other non-invasive imaging techniques, so we thought we could convert the intrinsic ability of these techniques to image blood vessels into a means for imaging light, by photosensitizing the blood vessels themselves,” Jasanoff says.

To make the blood vessels sensitive to light, the researcher engineered them to express a bacterial protein called Beggiatoa photoactivated adenylate cyclase (bPAC). When exposed to light, this enzyme produces a molecule called cAMP, which causes blood vessels to dilate. When blood vessels dilate, it alters the balance of oxygenated and deoxygenated hemoglobin, which have different magnetic properties. This shift in magnetic properties can be detected by MRI.

BPAC responds specifically to blue light, which has a short wavelength, so it detects light generated within close range. The researchers used a viral vector to deliver the gene for bPAC specifically to the smooth muscle cells that make up blood vessels. When this vector was injected in rats, blood vessels throughout a large area of the brain became light-sensitive.

“Blood vessels form a network in the brain that is extremely dense. Every cell in the brain is within a couple dozen microns of a blood vessel,” Jasanoff says. “The way I like to describe our approach is that we essentially turn the vasculature of the brain into a three-dimensional camera.”

Once the blood vessels were sensitized to light, the researchers implanted cells that had been engineered to express luciferase if a substrate called CZT is present. In the rats, the researchers were able to detect luciferase by imaging the brain with MRI, which revealed dilated blood vessels.

Tracking changes in the brain

The researchers then tested whether their technique could detect light produced by the brain’s own cells, if they were engineered to express luciferase. They delivered the gene for a type of luciferase called GLuc to cells in a deep brain region known as the striatum. When the CZT substrate was injected into the animals, MRI imaging revealed the sites where light had been emitted.

This technique, which the researchers dubbed bioluminescence imaging using hemodynamics, or BLUsH, could be used in a variety of ways to help scientists learn more about the brain, Jasanoff says.

For one, it could be used to map changes in gene expression, by linking the expression of luciferase to a specific gene. This could help researchers observe how gene expression changes during embryonic development and cell differentiation, or when new memories form. Luciferase could also be used to map anatomical connections between cells or to reveal how cells communicate with each other.

The researchers now plan to explore some of those applications, as well as adapting the technique for use in mice and other animal models.

The research was funded by the U.S. National Institutes of Health, the G. Harold and Leila Y. Mathers Foundation, Lore McGovern, Gardner Hendrie, Brendan Fikes, a fellowship from the German Research Foundation, a Marie Sklodowska-Curie Fellowship from the European Union, and a Y. Eva Tan Fellowship and a J. Douglas Tan Fellowship, both from the McGovern Institute for Brain Research.



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