Aurelia Butler

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    in Environment

    MIT Solve announces 2023 global challenges and Indigenous Communities Fellowship

    MIT Solve, an MIT initiative with a mission to drive innovation to solve world challenges, announced today the 2023 Global Challenges and the Indigenous Communities Fellowship. 

    Solve invites anyone from anywhere in the world to submit a solution to this year’s challenges by 12 p.m. EST on May 9. The 40 innovators — including eight new Indigenous Communities Fellows — will form the 2023 Solver Class, and pitch their solutions during Solve Challenge Finals on Sept. 17-18 in New York City. These selected teams will share over $1 million in available funding, take part in a nine-month support program, and join the Solve community made of cross-sector social impact leaders, to scale their solutions.

    Solve’s 2023 Global Challenges are: 

    For its second year, Solve will select a cohort of entrepreneurs among the 2023 Solver Class to join the Black and Brown Innovators in the U.S. Program. The program offers culturally-responsive support and partnership opportunities, and selected teams will participate in Solve’s annual U.S. Equity Summit. 

    In addition to the Global Challenges, Solve is also opening applications for the 2023 Indigenous Communities Fellowship. The fellowship, which looks for Native innovators in the United States and its territories, has now expanded eligibility to Canada. 

    “Every year we are inspired by people’s ingenuity and their determination to solve the most pressing issues of our time,” says Hala Hanna, acting executive director of MIT Solve. “We are excited to shine a spotlight on the most promising ones and grateful for our supporters who will help scale their impact.”

    Interested applicants can learn more and apply online at solve.mit.edu/challenges. 

    To date, the funding available for selected Solver teams and fellows includes:

    MIT Solve Funding — $400,000 with a $10,000 grant to each Solver team and fellow selected
    The GM Prize (supported by General Motors) — up to $150,000 across up to six solutions from the Learning for Civic Action Challenge, the Climate Adaptation & Low-Carbon Housing Challenge, and the 2023 Indigenous Communities Fellowship
    The AI for Humanity Prize (supported by The Patrick J. McGovern Foundation) — up to $150,000 to solutions that leverage data science, artificial intelligence, and/or machine learning to benefit humanity, selected from any of the 2023 Global Challenges
    The GSR Foundation Prize (supported by GSR Foundation) — up to $200,000 to innovative technology solutions from any of the 2023 Global Challenges, with a focus on solutions that use blockchain to improve financial inclusion
    Living Forests Prize (supported by Good Energies Foundation) — up to $100,000 across up to four solutions that help restore ecosystems or increase the use of sustainable forest products, selected from the Climate Adaptation & Low-Carbon Housing Challenge
    Those interested in sponsoring a prize should contact sue.kim@solve.mit.edu.

    Additionally, Solve Innovation Future will offer investment capital to Solver teams selected as a part of the 2023 class. To date, Solve Innovation Future has deployed over $1.3 million to more than 13 for-profit Solver team companies that are driving impact toward UN Sustainable Development Goals, and has catalyzed nearly seven times its investment in additional investment capital toward the Solver teams.

    The Solve community will convene on MIT’s campus for its flagship event Solve at MIT May 4-6 to celebrate the 2022 Solver Class. You may request an invitation here. Press interested in attending the event should contact maya.bingaman@solve.mit.edu. 

    Solve is a marketplace for social impact innovation. Through open innovation challenges, Solve finds incredible tech-based social entrepreneurs all around the world. Solve then brings together MIT’s innovation ecosystem and a community of members to fund and support these entrepreneurs to drive lasting, transformational impact. Solve has catalyzed over $60 million in commitments for Solver teams and entrepreneurs to date. More

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    in Environment

    Chess players face a tough foe: air pollution

    Here’s something else chess players need to keep in check: air pollution.

    That’s the bottom line of a newly published study co-authored by an MIT researcher, showing that chess players perform objectively worse and make more suboptimal moves, as measured by a computerized analysis of their games, when there is more fine particulate matter in the air.

    More specifically, given a modest increase in fine particulate matter, the probability that chess players will make an error increases by 2.1 percentage points, and the magnitude of those errors increases by 10.8 percent. In this setting, at least, cleaner air leads to clearer heads and sharper thinking.

    “We find that when individuals are exposed to higher levels of air pollution, they make more more mistakes, and they make larger mistakes,” says Juan Palacios, an economist in MIT’s Sustainable Urbanization Lab, and co-author of a newly published paper detailing the study’s findings.

    The paper, “Indoor Air Quality and Strategic Decision-Making,” appears today in advance online form in the journal Management Science. The authors are Steffen Künn, an associate professor in the School of Business and Economics at Maastricht University, the Netherlands; Palacios, who is head of research in the Sustainable Urbanization Lab, in MIT’s Department of Urban Studies and Planning (DUSP); and Nico Pestel, an associate professor in the School of Business and Economics at Maastricht University.

    The toughest foe yet?

    Fine particulate matter refers to tiny particles 2.5 microns or less in diameter, notated as PM2.5. They are often associated with burning matter — whether through internal combustion engines in autos, coal-fired power plants, forest fires, indoor cooking through open fires, and more. The World Health Organization estimates that air pollution leads to over 4 million premature deaths worldwide every year, due to cancer, cardiovascular problems, and other illnesses.

    Scholars have produced many studies exploring the effects of air pollution on cognition. The current study adds to that literature by analyzing the subject in a particularly controlled setting. The researchers studied the performance of 121 chess players in three seven-round tournaments in Germany in 2017, 2018, and 2019, comprising more than 30,000 chess moves. The scholars used three web-connected sensors inside the tournament venue to measure carbon dioxide, PM2.5 concentrations, and temperature, all of which can be affected by external conditions, even in an indoor setting. Because each tournament lasted eight weeks, it was possible to examine how air-quality changes related to changes in player performance.

    In a replication exercise, the authors found the same impacts of air pollution on some of the strongest players in the history of chess using data from 20 years of games from the first division of the German chess league. 

    To evaluate the matter of performance of players, meanwhile, the scholars used software programs that assess each move made in each chess match, identify optimal decisions, and flag significant errors.

    During the tournaments, PM2.5 concentrations ranged from 14 to 70 micrograms per cubic meter of air, levels of exposure commonly found in cities in the U.S. and elsewhere. The researchers examined and ruled out alternate potential explanations for the dip in player performance, such as increased noise. They also found that carbon dioxide and temperature changes did not correspond to performance changes. Using the standardized ratings chess players earn, the scholars also accounted for the quality of opponents each player faced. Ultimately, the analysis using the plausibly random variation in pollution driven by changes in wind direction confirms that the findings are driven by the direct exposure to air particles.

    “It’s pure random exposure to air pollution that is driving these people’s performance,” Palacios says. “Against comparable opponents in the same tournament round, being exposed to different levels of air quality makes a difference for move quality and decision quality.”

    The researchers also found that when air pollution was worse, the chess players performed even more poorly when under time constraints. The tournament rules mandated that 40 moves had to be made within 110 minutes; for moves 31-40 in all the matches, an air pollution increase of 10 micrograms per cubic meter led to an increased probability of error of 3.2 percent, with the magnitude of those errors increasing by 17.3 percent.

    “We find it interesting that those mistakes especially occur in the phase of the game where players are facing time pressure,” Palacios says. “When these players do not have the ability to compensate [for] lower cognitive performance with greater deliberation, [that] is where we are observing the largest impacts.”

    “You can live miles away and be affected”

    Palacios emphasizes that, as the study indicates, air pollution may affect people in settings where they might not think it makes a difference.

    “It’s not like you have to live next to a power plant,” Palacios says. “You can live miles away and be affected.”

    And while the focus of this particular study is tightly focused on chess players, the authors write in the paper that the findings have “strong implications for high-skilled office workers,” who might also be faced with tricky cognitive tasks in conditions of variable air pollution. In this sense, Palacios says, “The idea is to provide accurate estimates to policymakers who are making difficult decisions about cleaning up the environment.”

    Indeed, Palacios observes, the fact that even chess players — who spend untold hours preparing themselves for all kinds of scenarios they may face in matches — can perform worse when air pollution rises suggests that a similar problem could affect people cognitively in many other settings.

    “There are more and more papers showing that there is a cost with air pollution, and there is a cost for more and more people,” Palacios says. “And this is just one example showing that even for these very [excellent] chess players, who think they can beat everything — well, it seems that with air pollution, they have an enemy who harms them.”

    Support for the study was provided, in part, by the Graduate School of Business and Economics at Maastricht, and the Institute for Labor Economics in Bonn, Germany. More

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    in Environment

    Sensing with purpose

    Fadel Adib never expected that science would get him into the White House, but in August 2015 the MIT graduate student found himself demonstrating his research to the president of the United States.

    Adib, fellow grad student Zachary Kabelac, and their advisor, Dina Katabi, showcased a wireless device that uses Wi-Fi signals to track an individual’s movements.

    As President Barack Obama looked on, Adib walked back and forth across the floor of the Oval Office, collapsed onto the carpet to demonstrate the device’s ability to monitor falls, and then sat still so Katabi could explain to the president how the device was measuring his breathing and heart rate.

    “Zach started laughing because he could see that my heart rate was 110 as I was demoing the device to the president. I was stressed about it, but it was so exciting. I had poured a lot of blood, sweat, and tears into that project,” Adib recalls.

    For Adib, the White House demo was an unexpected — and unforgettable — culmination of a research project he had launched four years earlier when he began his graduate training at MIT. Now, as a newly tenured associate professor in the Department of Electrical Engineering and Computer Science and the Media Lab, he keeps building off that work. Adib, the Doherty Chair of Ocean Utilization, seeks to develop wireless technology that can sense the physical world in ways that were not possible before.

    In his Signal Kinetics group, Adib and his students apply knowledge and creativity to global problems like climate change and access to health care. They are using wireless devices for contactless physiological sensing, such as measuring someone’s stress level using Wi-Fi signals. The team is also developing battery-free underwater cameras that could explore uncharted regions of the oceans, tracking pollution and the effects of climate change. And they are combining computer vision and radio frequency identification (RFID) technology to build robots that find hidden items, to streamline factory and warehouse operations and, ultimately, alleviate supply chain bottlenecks.

    While these areas may seem quite different, each time they launch a new project, the researchers uncover common threads that tie the disciplines together, Adib says.

    “When we operate in a new field, we get to learn. Every time you are at a new boundary, in a sense you are also like a kid, trying to understand these different languages, bring them together, and invent something,” he says.

    A science-minded child

    A love of learning has driven Adib since he was a young child growing up in Tripoli on the coast of Lebanon. He had been interested in math and science for as long as he could remember, and had boundless energy and insatiable curiosity as a child.

    “When my mother wanted me to slow down, she would give me a puzzle to solve,” he recalls.

    By the time Adib started college at the American University of Beirut, he knew he wanted to study computer engineering and had his sights set on MIT for graduate school.

    Seeking to kick-start his future studies, Adib reached out to several MIT faculty members to ask about summer internships. He received a response from the first person he contacted. Katabi, the Thuan and Nicole Pham Professor in the Department of Electrical Engineering and Computer Science (EECS), and a principal investigator in the Computer Science and Artificial Intelligence Laboratory (CSAIL) and the MIT Jameel Clinic, interviewed him and accepted him for a position. He immersed himself in the lab work and, as the end of summer approached, Katabi encouraged him to apply for grad school at MIT and join her lab.

    “To me, that was a shock because I felt this imposter syndrome. I thought I was moving like a turtle with my research, but I did not realize that with research itself, because you are at the boundary of human knowledge, you are expected to progress iteratively and slowly,” he says.

    As an MIT grad student, he began contributing to a number of projects. But his passion for invention pushed him to embark into unexplored territory. Adib had an idea: Could he use Wi-Fi to see through walls?

    “It was a crazy idea at the time, but my advisor let me work on it, even though it was not something the group had been working on at all before. We both thought it was an exciting idea,” he says.

    As Wi-Fi signals travel in space, a small part of the signal passes through walls — the same way light passes through windows — and is then reflected by whatever is on the other side. Adib wanted to use these signals to “see” what people on the other side of a wall were doing.

    Discovering new applications

    There were a lot of ups and downs (“I’d say many more downs than ups at the beginning”), but Adib made progress. First, he and his teammates were able to detect people on the other side of a wall, then they could determine their exact location. Almost by accident, he discovered that the device could be used to monitor someone’s breathing.

    “I remember we were nearing a deadline and my friend Zach and I were working on the device, using it to track people on the other side of the wall. I asked him to hold still, and then I started to see him appearing and disappearing over and over again. I thought, could this be his breathing?” Adib says.

    Eventually, they enabled their Wi-Fi device to monitor heart rate and other vital signs. The technology was spun out into a startup, which presented Adib with a conundrum once he finished his PhD — whether to join the startup or pursue a career in academia.

    He decided to become a professor because he wanted to dig deeper into the realm of invention. But after living through the winter of 2014-2015, when nearly 109 inches of snow fell on Boston (a record), Adib was ready for a change of scenery and a warmer climate. He applied to universities all over the United States, and while he had some tempting offers, Adib ultimately realized he didn’t want to leave MIT. He joined the MIT faculty as an assistant professor in 2016 and was named associate professor in 2020.

    “When I first came here as an intern, even though I was thousands of miles from Lebanon, I felt at home. And the reason for that was the people. This geekiness — this embrace of intellect — that is something I find to be beautiful about MIT,” he says.

    He’s thrilled to work with brilliant people who are also passionate about problem-solving. The members of his research group are diverse, and they each bring unique perspectives to the table, which Adib says is vital to encourage the intellectual back-and-forth that drives their work.

    Diving into a new project

    For Adib, research is exploration. Take his work on oceans, for instance. He wanted to make an impact on climate change, and after exploring the problem, he and his students decided to build a battery-free underwater camera.

    Adib learned that the ocean, which covers 70 percent of the planet, plays the single largest role in the Earth’s climate system. Yet more than 95 percent of it remains unexplored. That seemed like a problem the Signal Kinetics group could help solve, he says.

    But diving into this research area was no easy task. Adib studies Wi-Fi systems, but Wi-Fi does not work underwater. And it is difficult to recharge a battery once it is deployed in the ocean, making it hard to build an autonomous underwater robot that can do large-scale sensing.

    So, the team borrowed from other disciplines, building an underwater camera that uses acoustics to power its equipment and capture and transmit images.

    “We had to use piezoelectric materials, which come from materials science, to develop transducers, which come from oceanography, and then on top of that we had to marry these things with technology from RF known as backscatter,” he says. “The biggest challenge becomes getting these things to gel together. How do you decode these languages across fields?”

    It’s a challenge that continues to motivate Adib as he and his students tackle problems that are too big for one discipline.

    He’s excited by the possibility of using his undersea wireless imaging technology to explore distant planets. These same tools could also enhance aquaculture, which could help eradicate food insecurity, or support other emerging industries.

    To Adib, the possibilities seem endless.

    “With each project, we discover something new, and that opens up a whole new world to explore. The biggest driver of our work in the future will be what we think is impossible, but that we could make possible,” he says. More

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    in Environment

    Preparing to be prepared

    The Kobe earthquake of 1995 devastated one of Japan’s major cities, leaving over 6,000 people dead while destroying or making unusable hundreds of thousands of structures. It toppled elevated freeway segments, wrecked mass transit systems, and damaged the city’s port capacity.

    “It was a shock to a highly engineered, urban city to have undergone that much destruction,” says Miho Mazereeuw, an associate professor at MIT who specializes in disaster resilience.

    Even in a country like Japan, with advanced engineering, and policies in place to update safety codes, natural forces can overwhelm the built environment.

    “There’s nothing that’s ever guaranteed safe,” says Mazereeuw, an associate professor of architecture and urbanism in MIT’s Department of Architecture and director of the Urban Risk Lab. “We [think that] through technology and engineering we can solve things and fight nature. Whereas it’s really that we’re living with nature. We’re part of this natural ecosystem.”

    That’s why Mazereeuw’s work on disaster resilience focuses on plans, people, and policies, well as technology and design to prepare for the future. In the Urban Risk Lab, which Mazereeuw founded, several projects are based on the design of physical objects, spaces, and software platforms, but many others involve community-level efforts, so that local governments have workable procedures in case of emergency.

    “What we can do for ourselves and each other is have plans in place so that if something does happen, the level of chaos and fear can be reduced and we can all be there to help each other through,” Mazereeuw says. When it comes to disaster preparedness, she adds, “Definitely a lot of it is on the built environment side of things, but a lot of it is also social, making sure that in our communities, we know who would need help, and we have those kinds of relationships beforehand.”

    The Kobe earthquake was a highly influential event for Mazereeuw. She has researched the response to it and has a book coming out about natural disasters, policies, and design in Japan. Beyond that, the Kobe event helped reinforce her sense that when it comes to disaster preparedness, progress can be made many ways. For her research, teaching, and innovative work at the Urban Risk Lab, Mazereeuw was granted tenure at MIT last year.

    Two cultures grappling with nature

    Mazereeuw has one Dutch parent and one Japanese parent, and both cultures helped produce her interest in managing natural forces. On her Dutch side, many family friends were involved with local government and water management — practically an existential issue in a country that sits largely below sea level.

    Mazereeuw’s parents, however, were living in Japan in 1995. And while they happened to be away while the Kobe earthquake hit, her Japanese links helped spur her interest in studying the event and its aftermath.

    “I think that was a wake-up call for me, too, about how we need to plan and design cities to reduce the impact of chaos at the time of disasters,” Mazereeuw says.

    Mazereeuw earned her undergraduate degree from Wesleyan University, majoring in earth and environmental sciences and in studio art. After working in an architectural office in Tokyo, she decided to attend graduate school, receiving her dual masters from Harvard University’s Graduate School of Design, with a thesis about Kobe and disaster readiness. She then worked in architecture offices, including the Office of Metropolitan Architecture in Rotterdam, but returned to academia to work on climate change and disaster resilience.   

    Mazereeuw’s book, “Design Before Disaster,” explores this subject in depth, from urban planning to coastal-safety strategies to community-based design frameworks, and is forthcoming from the University of Virginia Press.

    Since joining the MIT faculty, Mazereeuw has also devoted significant time to the launch and growth of the Urban Risk Lab, an interdisciplinary group working on an array of disaster-preparedness efforts. One such project has seen lab members work with local officials from many places — including Massachusetts, California, Georgia, and Puerto Rico — to add to their own disaster-preparedness planning.

    A plan developed by local officials with community input, Mazereeuw suggests, will likely function better than one produced by, say, consultants from outside a community, as she has seen happen many times: “A report on a dusty shelf isn’t actionable,” she says. “This way it’s a decision-making process by the people involved.”

    In a project based on physical design, the Urban Risk Lab has also been working with the U.S. Federal Emergency Management Agency on an effort to produce temporary postdisaster housing for the OCONUS region (Alaska, Hawaii, and other U.S. overseas territories). The lab’s design, called SEED (Shelter for Emergency Expansion Design), features a house that is compact enough to be shipped anywhere and unfolds on-site, while being sturdy enough to withstand follow-up events such as hurricanes, and durable enough to be incorporated into longer-term housing designs.

    “We felt it had to be really, really good quality, so it would be a resource, rather than something temporary that disintegrates after five years,” Mazereeuw says. “It’s built to be a small safety shelter but also could be part of a permanent house.”

    A grand challenge, and a plethora of projects

    Mazereeuw is also a co-lead of one of the five multiyear projects selected in 2022 to move forward as part of MIT’s Climate Grand Challenges competition. Along with Kerry Emanuel and Paul O’Gorman, of MIT’s Department of Earth, Atmospheric and Planetary Sciences, Mazereeuw will help direct a project advancing climate modeling by quantifying the risk of extreme weather events for specific locations. The idea is to help vulnerable urban centers and other communities prepare for such events.

    The Urban Risk Lab has many other kinds of projects in its portfolio, following Mazereeuw’s own interest in conceptualizing disaster preparedness broadly. In collaboration with officials in Japan, and with support from Google, lab members worked on interactive, real-time flood-mapping software, in which residents can help officials know where local flooding has reached emergency levels. The researchers also created an AI module to prioritize the information.

    “Residents really have the most localized information, which you can’t get from a satellite,” Mazereeuw says. “They’re also the ones who learn about it first, so they have a lot of information that emergency managers can use for their response. The program is really meant to be a conduit between the efforts of emergency managers and residents, so that information flow can go in both directions.”

    Lab members in the past have also mapped the porosity of the MIT campus, another effort that used firsthand knowledge. Additionally, lab members are currently engaging with a university in Chile to design tsunami response strategies; developing a community mapping toolkit for resilience planning in Thailand and Vietnam; and working with Mass Audubon to design interactive furniture for children to learn about ecology.  

    “Everything is tied together with this interest in raising awareness and engaging people,” Mazereeuw says.

    That also describes Mazereeuw’s attitude about participation in the Urban Risk Lab, a highly cross-disciplinary place with members who have gravitated to it from around MIT.

    “Our lab is extremely interdisciplinary,” Mazereeuw says. “We have students coming in from all over, from different parts of campus. We have computer science and engineering students coming into the lab and staying to get their graduate degrees alongside many architecture and planning students.” The lab also has five full-time researchers — Aditya Barve, Larisa Ovalles, Mayank Ojha, Eakapob Huangthananpan, and Saeko Baird — who lead their own projects and research groups.

    What those lab members have in common is a willingness to think proactively about reducing disaster impacts. Being prepared for those events itself requires preparation.

    Even in the design world, Mazereeuw says, “People are reactive. Because something has happened, that’s when they go in to help. But I think we can have a larger impact by anticipating and designing for these issues beforehand.” More

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    in Environment

    Study: Extreme heat is changing habits of daily life

    Extreme temperatures make people less likely to pursue outdoor activities they would otherwise make part of their daily routine, a new study led by MIT researchers has confirmed.

    The data-rich study, set in China, shows that when hourly temperatures reach 30 degrees Celsius (86 degrees Fahrenheit), people are 5 percent less likely to go to public parks, and when hourly temperatures hit 35 C (95 F), people are 13 percent less likely to go to those parks.

    “We did observe adaptation,” says Siqi Zheng, an MIT professor and co-author of a new paper detailing the study’s findings. She adds: “Environmental hazards hurt the daily quality of life. Yes, people protect themselves [by limiting activity], but they lose the benefit of going out to enjoy themselves in nature, or meeting friends in parks.”

    The research adds to our knowledge about the effects of a warming climate by quantifying the effects of hot temperatures on the activity of people within a given day — how they shift their activities from hotter to cooler time periods — and not just across longer periods of time.

    “We found that if we take into account this within-day adaptation, extreme temperatures actually have a much larger effect on human activity than the previous daily or monthly estimations [indicate],” says Yichun Fan, an MIT doctoral candidate and another of the paper’s co-authors.

    The paper, “Intraday Adaptation to Extreme Temperatures in Outdoor Activity,” is published this week in Nature Scientific Reports. The authors are Fan, a doctoral student in MIT’s Department of Urban Studies and Planning (DUSP); Jianghao Wang, a professor at the Chinese Academy of Sciences; Nick Obradovich, chief scientist at Project Regeneration; and Zheng, who is the STL Champion Professor of Urban and Real Estate Sustainability at MIT’s Center for Real Estate and DUSP, and faculty director of the MIT Center for Real Estate.

    To conduct the study, the researchers used anonymized data for 900 million cellphone users in China in 2017, studying a total of 60 billion separate cellphone location queries per day available through the technology firm Tencent. With this data, the scholars also examined activity in 10,499 parks across the country, comparing useage totals across a range of conditions. And they obtained temperature data from about 2,000 weather stations in China.

    Ultimately, as the scholars write in the paper, they were able to “document large and significant activity-depressing and activity-delaying effects” on park visits as a result of ultrahot temperatures.

    “People have intraday adaptation patterns that hadn’t been documented in the previous literature,” Fan says. “These have important implications about people’s heat exposure and how future climate change will affect people’s activity and health.”

    As Zheng points out, altered use of public spaces affects daily routines not only in terms of individual activity and exercise, but also in terms of social and community life.

    “Extreme climates will reduce people’s opportunities to socialize in cities, or just watch kids playing basketball or soccer, which is not good,” she says. “We want people to have a wide-ranging urban life. There is a social cost to this adaptation.”

    As the research indicates, people clearly adapt to temperature spikes. The data also show that evening use of parks increases on extremely hot days, but only after conditions have cooled down. While that seems like a beneficial adaptation to very hot weather, the scholars citing existing research suggest people may sleep less as a result of making this kind of change to their daily routines.

    “Adaptation also has its own cost,” Fan says. “People significantly increased their nighttime outdoor activity, which means they delayed their nighttime, which will have a significant health implication, when you consider the potential sleep disruption.”

    All told, the study provides data, and a method, for better characterizing the effects on climate change on human activity in detail.

    “If we have more and more granular data about future climate scenarios, they support better predictions about these scenarios, reflecting people’s dynamic behaviors, and the health implications,” says Fan, whose doctoral research incorporates this work and other related studies on climate and urban activity.

    The researchers also note that the research methods used in this study could be applied to additional future studies of many other aspects of urban life, including street-level retail activities, and other things with implications for economic activity, real estate, and urban planning.

    “This relates to many other issues,” Zheng says.

    Jianghao Wang received funding from the National Key Research and Development Program of China, the National Natural Science Foundation of China, and the Youth Innovation Promotion Association of the Chinese Academy of Sciences. More

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    in Environment

    Moving water and earth

    As a river cuts through a landscape, it can operate like a conveyer belt, moving truckloads of sediment over time. Knowing how quickly or slowly this sediment flows can help engineers plan for the downstream impact of restoring a river or removing a dam. But the models currently used to estimate sediment flow can be off by a wide margin.

    An MIT team has come up with a better formula to calculate how much sediment a fluid can push across a granular bed — a process known as bed load transport. The key to the new formula comes down to the shape of the sediment grains.

    It may seem intuitive: A smooth, round stone should skip across a river bed faster than an angular pebble. But flowing water also pushes harder on the angular pebble, which could erase the round stone’s advantage. Which effect wins? Existing sediment transport models surprisingly don’t offer an answer, mainly because the problem of measuring grain shape is too unwieldy: How do you quantify a pebble’s contours?

    The MIT researchers found that instead of considering a grain’s exact shape, they could boil the concept of shape down to two related properties: friction and drag. A grain’s drag, or resistance to fluid flow, relative to its internal friction, the resistance to sliding past other grains, can provide an easy way to gauge the effects of a grain’s shape.

    When they incorporated this new mathematical measure of grain shape into a standard model for bed load transport, the new formula made predictions that matched experiments that the team performed in the lab.

    “Sediment transport is a part of life on Earth’s surface, from the impact of storms on beaches to the gravel nests in mountain streams where salmon lay their eggs,” the team writes of their new study, appearing today in Nature. “Damming and sea level rise have already impacted many such terrains and pose ongoing threats. A good understanding of bed load transport is crucial to our ability to maintain these landscapes or restore them to their natural states.”

    The study’s authors are Eric Deal, Santiago Benavides, Qiong Zhang, Ken Kamrin, and Taylor Perron of MIT, and Jeremy Venditti and Ryan Bradley of Simon Fraser University in Canada.

    Figuring flow

    Video of glass spheres (top) and natural river gravel (bottom) undergoing bed load transport in a laboratory flume, slowed down 17x relative to real time. Average grain diameter is about 5 mm. This video shows how rolling and tumbling natural grains interact with one another in a way that is not possible for spheres. What can’t be seen so easily is that natural grains also experience higher drag forces from the flowing water than spheres do.

    Credit: Courtesy of the researchers

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    Bed load transport is the process by which a fluid such as air or water drags grains across a bed of sediment, causing the grains to hop, skip, and roll along the surface as a fluid flows through. This movement of sediment in a current is what drives rocks to migrate down a river and sand grains to skip across a desert.

    Being able to estimate bed load transport can help scientists prepare for situations such as urban flooding and coastal erosion. Since the 1930s, one formula has been the go-to model for calculating bed load transport; it’s based on a quantity known as the Shields parameter, after the American engineer who originally derived it. This formula sets a relationship between the force of a fluid pushing on a bed of sediment, and how fast the sediment moves in response. Albert Shields incorporated certain variables into this formula, including the average size and density of a sediment’s grains — but not their shape.

    “People may have backed away from accounting for shape because it’s one of these very scary degrees of freedom,” says Kamrin, a professor of mechanical engineering at MIT. “Shape is not a single number.”

    And yet, the existing model has been known to be off by a factor of 10 in its predictions of sediment flow. The team wondered whether grain shape could be a missing ingredient, and if so, how the nebulous property could be mathematically represented.

    “The trick was to focus on characterizing the effect that shape has on sediment transport dynamics, rather than on characterizing the shape itself,” says Deal.

    “It took some thinking to figure that out,” says Perron, a professor of geology in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “But we went back to derive the Shields parameter, and when you do the math, this ratio of drag to friction falls out.”

    Drag and drop

    Their work showed that the Shields parameter — which predicts how much sediment is transported — can be modified to include not just size and density, but also grain shape, and furthermore, that a grain’s shape can be simply represented by a measure of the grain’s drag and its internal friction. The math seemed to make sense. But could the new formula predict how sediment actually flows?

    To answer this, the researchers ran a series of flume experiments, in which they pumped a current of water through an inclined tank with a floor covered in sediment. They ran tests with sediment of various grain shapes, including beds of round glass beads, smooth glass chips, rectangular prisms, and natural gravel. They measured the amount of sediment that was transported through the tank in a fixed amount of time. They then determined the effect of each sediment type’s grain shape by measuring the grains’ drag and friction.

    For drag, the researchers simply dropped individual grains down through a tank of water and gathered statistics for the time it took the grains of each sediment type to reach the bottom. For instance, a flatter grain type takes a longer time on average, and therefore has greater drag, than a round grain type of the same size and density.

    To measure friction, the team poured grains through a funnel and onto a circular tray, then measured the resulting pile’s angle, or slope — an indication of the grains’ friction, or ability to grip onto each other.

    For each sediment type, they then worked the corresponding shape’s drag and friction into the new formula, and found that it could indeed predict the bedload transport, or the amount of moving sediment that the researchers measured in their experiments.

    The team says the new model more accurately represents sediment flow. Going forward, scientists and engineers can use the model to better gauge how a river bed will respond to scenarios such as sudden flooding from severe weather or the removal of a dam.

    “If you were trying to make a prediction of how fast all that sediment will get evacuated after taking a dam out, and you’re wrong by a factor of three or five, that’s pretty bad,” Perron says. “Now we can do a lot better.”

    This research was supported, in part, by the U.S. Army Research Laboratory. More

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    in Environment

    Looking to the past to prepare for an uncertain future

    Aviva Intveld, an MIT senior majoring in Earth, atmospheric, and planetary sciences, is accustomed to city life. But despite hailing from metropolitan Los Angeles, she has always maintained a love for the outdoors.

    “Growing up in L.A., you just have a wealth of resources when it comes to beautiful environments,” she says, “but you’re also constantly living connected to the environment.” She developed a profound respect for the natural world and its effects on people, from the earthquakes that shook the ground to the wildfires that displaced inhabitants.

    “I liked the lifestyle that environmental science afforded,” Intveld recalls. “I liked the idea that you can make a career out of spending a huge amount of time in the field and exploring different parts of the world.”

    From the moment she arrived at MIT, Intveld threw herself into research on and off campus. During her first semester, she joined Terrascope, a program that encourages first-year students to tackle complex, real-world problems. Intveld and her cohort developed proposals to make recovery from major storms in Puerto Rico faster, more sustainable, and more equitable.

    Intveld also spent a semester studying drought stress in the lab of Assistant Professor David Des Marais, worked as a research assistant at a mineral sciences research lab back in L.A., and interned at the World Wildlife Fund. Most of her work focused on contemporary issues like food insecurity and climate change. “I was really interested in questions about today,” Intveld says.

    Her focus began to shift to the past when she interned as a research assistant at the Marine Geoarchaeology and Micropaleontology Lab at the University of Haifa. For weeks, she would spend eight hours a day hunched over a microscope, using a paintbrush to sort through grains of sand from the coastal town of Caesarea. She was looking for tiny spiral-shaped fossils of foraminifera, an organism that resides in seafloor sediments.

    These microfossils can reveal a lot about the environment in which they originated, including extreme weather events. By cataloging diverse species of foraminifera, Intveld was helping to settle a rather niche debate in the field of geoarchaeology: Did tsunamis destroy the harbor of Caesarea during the time of the ancient Romans?

    But in addition to figuring out if and when these natural disasters occurred, Intveld was interested in understanding how ancient communities prepared for and recovered from them. What methods did they use? Could those same methods be used today?

    Intveld’s research at the University of Haifa was part of the Onward Israel program, which offers young Jewish people the chance to participate in internships, academic study, and fellowships in Israel. Intveld describes the experience as a great opportunity to learn about the culture, history, and diversity of the Israeli community. The trip was also an excellent lesson in dealing with challenging situations.

    Intveld suffers from claustrophobia, but she overcame her fears to climb through the Bar Kokhba caves, and despite a cat allergy, she grew to adore the many stray cats that roam the streets of Haifa. “Sometimes you can’t let your physical limitations stop you from doing what you love,” she quips.

    Over the course of her research, Intveld has often found herself in difficult and even downright dangerous situations, all of which she looks back on with good humor. As part of an internship with the National Oceanic and Atmospheric Administration, she spent three months investigating groundwater in Homer, Alaska. While she was there, she learned to avoid poisonous plants out in the field, got lost bushwhacking, and was twice charged by a moose.

    These days, Intveld spends less time in the field and more time thinking about the ancient past. She works in the lab of Associate Professor David McGee, where her undergraduate thesis research focuses on reconstructing the paleoclimate and paleoecology of northeastern Mexico during the Early Holocene. To get an idea of what the Mexican climate looked like thousands of years ago, Intveld analyzes stable isotopes and trace elements in stalagmites taken from Mexican caves. By analyzing the isotopes of carbon and oxygen present in these stalagmites, which were formed over thousands of years from countless droplets of mineral-rich rainwater, Intveld can estimate the amount of rainfall and average temperature in a given time period.

    Intveld is primarily interested in how the area’s climate may have influenced human migration. “It’s very interesting to learn about the history of human motivation, what drives us to do what we do,” she explains. “What causes humans to move, and what causes us to stay?” So far, it seems the Mexican climate during the Early Holocene was quite inconsistent, with oscillating periods of wet and dry, but Intveld needs to conduct more research before drawing any definitive conclusions.

    Recent research has linked periods of drought in the geological record to periods of violence in the archaeological one, suggesting ancient humans often fought over access to water. “I think you can easily see the connections to stuff that we deal with today,” Intveld says, pointing out the parallels between paleolithic migration and today’s climate refugees. “We have to answer a lot of difficult questions, and one way that we can do so is by looking to see what earlier human communities did and what we can learn from them.”

    Intveld recognizes the impact of the past on our present and future in many other areas. She works as a tour guide for the List Visual Arts Center, where she educates people about public art on the MIT campus. “[Art] interested me as a way to experience history and learn about the story of different communities and people over time,” she says.

    Intveld is also unafraid to acknowledge the history of discrimination and exclusion in science. “Earth science has a big problem when it comes to inclusion and diversity,” she says. As a member of the EAPS Diversity, Equity and Inclusion Committee, she aims to make earth science more accessible.

    “Aviva has a clear drive to be at the front lines of geoscience research, connecting her work to the urgent environmental issues we’re all facing,” says McGee. “She also understands the critical need for our field to include more voices, more perspectives — ultimately making for better science.”

    After MIT, Intveld hopes to pursue an advanced degree in the field of sustainable mining. This past spring, she studied abroad at Imperial College London, where she took courses within the Royal School of Mines. As Intveld explains, mining is becoming crucial to sustainable energy. The rise of electric vehicles in places like California has increased the need for energy-critical elements like lithium and cobalt, but mining for these elements often does more harm than good. “The current mining complex is very environmentally destructive,” Intveld says.

    But Intveld hopes to take the same approach to mining she does with her other endeavors — acknowledging the destructive past to make way for a better future. More

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    in Environment

    Sustainable supply chains put the customer first

    When we consider the supply chain, we typically think of factories, ships, trucks, and warehouses. Yet, the customer side is equally important, especially in efforts to make our distribution networks more sustainable. Customers are an untapped resource in building sustainability, says Josué C. Velázquez Martínez, a research scientist at MIT Center for Transportation and Logistics. 

    Velázquez Martínez, who is director of MIT’s Sustainable Supply Chain Lab, investigates how customer-facing supply chains can be made more environmentally and socially sustainable. One way is a Green Button project that explores how to optimize e-commerce delivery schedules to reduce carbon emissions and persuade customers to use less carbon-intensive four- or five-day shipping options instead of one or two days. Velázquez Martínez has also launched the MIT Low Income Firms Transformation (LIFT) Lab that is researching ways to improve micro-retailer supply chains in the developing world to provide owners with the necessary tools for survival.  

    “The definition of sustainable supply chain keeps evolving because things that were sustainable 20 to 30 years ago are not as sustainable now,” says Velázquez Martínez. “Today, there are more companies that are capturing information to build strategies for environmental, economic, and social sustainability. They are investing in alternative energy and other solutions to make the supply chain more environmentally friendly and are tracking their suppliers and identifying key vulnerabilities. A big part of this is an attempt to create fairer conditions for people who work in supply chains or are dependent on them.”

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    The move toward sustainable supply chain is being driven as much by people as by companies, whether they are playing the role of selective consumer or voting citizens. The consumer aspect is often overlooked, says Velázquez Martínez. “Consumers are the ones who move the supply chain. We are looking at how companies can provide transparency to involve customers in their sustainability strategy.” 

    Proposed solutions for sustainability are not always as effective as promised. Some fashion rental schemes fall into this category, says Velázquez Martínez. “There are many new rental companies that are trying to get more use out of clothes to offset the emissions associated with production. We recently researched the environmental impact of monthly subscription models where consumers pay a fee to receive clothes for a month before returning them, as well as peer-to-peer sharing models.” 

    The researchers found that while rental services generally have a lower carbon footprint than retail sales, hidden emissions from logistics played a surprisingly large role. “First, you need to deliver the clothes and pick them up, and there are high return rates,” says Velázquez Martínez. “When you factor in dry cleaning and packaging emissions, the rental models in some cases have a worse carbon footprint than buying new clothes.” Peer-to-peer sharing could be better, he adds, but that depends on how far the consumers travel to meet-up points. 

    Typically, says Velázquez Martínez, garment types that are frequently used are not well suited to rental models. “But for specialty clothes such as wedding dresses or prom dresses, it is better to rent.” 

    Waiting a few days to save the planet 

    Even before the pandemic, online retailing gained a second wind due to low-cost same- and next-day delivery options. While e-commerce may have its drawbacks as a contributor to social isolation and reduced competition, it has proven itself to be far more eco-friendly than brick-and-mortar shopping, not to mention a lot more convenient. Yet rapid deliveries are cutting into online-shopping’s carbon-cutting advantage.

    In 2019, MIT’s Sustainable Supply Chain Lab launched a Green Bottle project to study the rapid delivery phenomenon. The project has been “testing whether consumers would be willing to delay their e-commerce deliveries to reduce the environmental impact of fast shipping,” says Velázquez Martínez. “Many companies such as Walmart and Target have followed Amazon’s 2019 strategy of moving from two-day to same-day delivery. Instead of sending a fully loaded truck to a neighborhood every few days, they now send multiple trucks to that neighborhood every day, and there are more days when trucks are targeting each neighborhood. All this increases carbon emissions and makes it hard for shippers to consolidate. ”  

    Working with Coppel, one of Mexico’s largest retailers, the Green Button project inspired a related Consolidation Ecommerce Project that built a large-scale mathematical model to provide a strategy for consolidation. The model determined what delivery time window each neighborhood demands and then calculated the best day to deliver to each neighborhood to meet the desired window while minimizing carbon emissions. 

    No matter what mixture of delivery times was used, the consolidation model helped retailers schedule deliveries more efficiently. Yet, the biggest cuts in emissions emerged when customers were willing to wait several days.

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    “When we ran a month-long simulation comparing our model for four-to-five-day delivery with Coppel’s existing model for one- or two-day delivery, we saw savings in fuel consumption of over 50 percent on certain routes” says Velázquez Martínez. “This is huge compared to other strategies for squeezing more efficiency from the last-mile supply chain, such as routing optimization, where savings are close to 5 percent. The optimal solution depends on factors such as the capacity for consolidation, the frequency of delivery, the store capacity, and the impact on inbound operations.” 

    The researchers next set out to determine if customers could be persuaded to wait longer for deliveries. Considering that the price differential is low or nonexistent, this was a considerable challenge. Yet, the same day habit is only a few years old, and some consumers have come to realize they don’t always need rapid deliveries. “Some consumers who order by rapid delivery find they are too busy to open the packages right away,” says Velázquez Martínez.  

    Trees beat kilograms of CO2

    The researchers set out to find if consumers would be willing to sacrifice a bit of convenience if they knew they were helping to reduce climate change. The Green Button project tested different public outreach strategies. For one test group, they reported the carbon impact of delivery times in kilograms of carbon dioxide (CO2). Another group received the information expressed in terms of the energy required to recycle a certain amount of garbage. A third group learned about emissions in terms of the number of trees required to trap the carbon. “Explaining the impact in terms of trees led to almost 90 percent willing to wait another day or two,” says Velázquez Martínez. “This is compared to less than 40 percent for the group that received the data in kilograms of CO2.” 

    Another surprise was that there was no difference in response based on income, gender, or age. “Most studies of green consumers suggest they are predominantly high income, female, highly educated, or younger,” says Velázquez Martínez. “However, our results show that the differences were the same between low and high income, women and men, and younger and older people. We have shown that disclosing emissions transparently and making the consumer a part of the strategy can be a new opportunity for more consumer-driven logistics sustainability.” 

    The researchers are now developing similar models for business-to-business (B2B) e-commerce. “We found that B2B supply chain emissions are often high because many shipping companies require strict delivery windows,” says Velázquez Martínez.  

    The B2B models drill down to examine the Corporate Value Chain (Scope 3) emissions of suppliers. “Although some shipping companies are now asking their suppliers to review emissions, it is a challenge to create a transparent supply chain,” says Velázquez Martínez.  “Technological innovations have made it easier, starting with RFID [radio frequency identification], and then real-time GPS mapping and blockchain. But these technologies need to be more accessible and affordable, and we need more companies willing to use them.” 

    Some companies have been hesitant to dig too deeply into their supply chain, fearing they might uncover a scandal that might risk their reputation, says Velázquez Martínez. Other organizations are forced to look at the issue when nongovernmental organizations research sustainability issues such as social injustice in sweat shops and conflict mineral mines. 

    One challenge to building a transparent supply chain is that “in many companies, the sustainability teams are separate from the rest of the company,” says Velázquez Martínez. “Even if the CEOs receive information on sustainability issues, it often doesn’t filter down because the information does not belong to the planners or managers. We are pushing companies to not only account for sustainability factors in supply chain network design but also examine daily operations that affect sustainability. This is a big topic now: How can we translate sustainability information into something that everybody can understand and use?” 

    LIFT Lab lifts micro-retailers  

    In 2016, Velázquez Martínez launched the MIT GeneSys project to gain insights into micro and small enterprises (MSEs) in developing countries. The project released a GeneSys mobile app, which was used by more than 500 students throughout Latin America to collect data on more than 800 microfirms. In 2022, he launched the LIFT Lab, which focuses more specifically on studying and improving the supply chain for MSEs.  

    Worldwide, some 90 percent of companies have fewer than 10 employees. In Latin America and the Caribbean, companies with fewer than 50 employees represent 99 percent of all companies and 47 percent of employment. 

    Although MSEs represent much of the world’s economy, they are poorly understood, notes Velázquez Martínez. “Those tiny businesses are driving a lot of the economy and serve as important customers for the large companies working in developing countries. They range from small businesses down to people trying to get some money to eat by selling cakes or tacos through their windows.”  

    The MIT LIFT Lab researchers investigated whether MSE supply chain issues could help shed light on why many Latin American countries have been limited to marginal increases in gross domestic product. “Large companies from the developed world that are operating in Latin America, such as Unilever, Walmart, and Coca-Cola, have huge growth there, in some cases higher than they have in the developed world,” says Velázquez Martínez. “Yet, the countries are not developing as fast as we would expect.” 

    The LIFT Lab data showed that while the multinationals are thriving in Latin America, the local MSEs are decreasing in productivity. The study also found the trend has worsened with Covid-19.  

    The LIFT Lab’s first big project, which is sponsored by Mexican beverage and retail company FEMSA, is studying supply chains in Mexico. The study spans 200,000 micro-retailers and 300,000 consumers. In a collaboration with Tecnológico de Monterrey, hundreds of students are helping with a field study.  

    “We are looking at supply chain management and business capabilities and identifying the challenges to adoption of technology and digitalization,” says Velázquez Martínez. “We want to find the best ways for micro-firms to work with suppliers and consumers by identifying the consumers who access this market, as well as the products and services that can best help the micro-firms drive growth.” 

    Based on the earlier research by GeneSys, Velázquez Martínez has developed some hypotheses for potential improvements for micro-retailer supply chain, starting with payment terms. “We found that the micro-firms often get the worst purchasing deals. Owners without credit cards and with limited cash often buy in smaller amounts at much higher prices than retailers like Walmart. The big suppliers are squeezing them.” 

    While large retailers usually get 60 to 120 days to pay, micro-retailers “either pay at the moment of the transaction or in advance,” says Velázquez Martínez. “In a study of 500 micro-retailers in five countries in Latin America, we found the average payment time was minus seven days payment in advance. These terms reduce cash availability and often lead to bankruptcy.” 

    LIFT Lab is working with suppliers to persuade them to offer a minimum payment time of two weeks. “We can show the suppliers that the change in terms will let them move more product and increase sales,” says Velázquez Martínez. “Meanwhile, the micro-retailers gain higher profits and become more stable, even if they may pay a bit more.” 

    LIFT Lab is also looking at ways that micro-retailers can leverage smartphones for digitalization and planning. “Some of these companies are keeping records on napkins,” says Velázquez Martínez. “By using a cellphone, they can charge orders to suppliers and communicate with consumers. We are testing different dashboards for mobile apps to help with planning and financial performance. We are also recommending services the stores can provide, such as paying electricity or water bills. The idea is to build more capabilities and knowledge and increase business competencies for the supply chain that are tailored for micro-retailers.” 

    From a financial perspective, micro-retailers are not always the most efficient way to move products. Yet they also play an important role in building social cohesion within neighborhoods. By offering more services, the corner bodega can bring people together in ways that are impossible with e-commerce and big-box stores.  

    Whether the consumers are micro-firms buying from suppliers or e-commerce customers waiting for packages, “transparency is key to building a sustainable supply chain,” says Velázquez Martínez. “To change consumer habits, consumers need to be better educated on the impacts of their behaviors. With consumer-facing logistics, ‘The last shall be first, and the first last.’” More