The rapid advancement of artificial intelligence (AI) has brought about significant benefits and transformative changes across various industries. However, it has also introduced new risks and challenges, particularly when it comes to fraud and security. Deepfakes, a product of generative AI, are becoming increasingly sophisticated and…
A community collaboration for progress
While decades of discriminatory policies and practices continue to fuel the affordable housing crisis in the United States, less than three miles from the MIT campus exists a beacon of innovation and community empowerment.
“We are very proud to continue MIT’s long-standing partnership with Camfield Estates,” says Catherine D’Ignazio, associate professor of urban science and planning. “Camfield has long been an incubator of creative ideas focused on uplifting their community.”
D’Ignazio co-leads a research team focused on housing as part of the MIT Initiative for Combatting Systemic Racism (ICSR) led by the Institute for Data, Systems, and Society (IDSS). The group researches the uneven impacts of data, AI, and algorithmic systems on housing in the United States, as well as ways that these same tools could be used to address racial disparities. The Camfield Tenant Association is a research partner providing insight into the issue and relevant data, as well as opportunities for MIT researchers to solve real challenges and make a local impact.
MIT Initiative on Combatting Systemic Racism – Housing
Video: MIT Sociotechnical Systems Research Center
Formerly known as “Camfield Gardens,” the 102-unit housing development in Roxbury, Massachusetts, was among the pioneering sites in the 1990s to engage in the U.S. Department of Housing and Urban Development’s (HUD) program aimed at revitalizing disrepaired public housing across the country. This also served as the catalyst for their collaboration with MIT, which began in the early 2000s.
“The program gave Camfield the money and energy to tear everything on the site down and build it back up anew, in addition to allowing them to buy the property from the city for $1 and take full ownership of the site,” explains Nolen Scruggs, a master’s student in the MIT Department of Urban Studies and Planning (DUSP) who has worked with Camfield over the past few years as part of ICSR’s housing vertical team. “At the time, MIT graduate students helped start a ‘digital divide’ bridge gap program that later evolved into the tech lab that is still there today, continuing to enable residents to learn computer skills and things they might need to get a hand up.”
Because of that early collaboration, Camfield Estates reached out to MIT in 2022 to start a new chapter of collaboration with students. Scruggs spent a few months building a team of students from Harvard University, Wentworth Institute of Technology, and MIT to work on a housing design project meant to help the Camfield Tenants Association prepare for their looming redevelopment needs.
“One of the things that’s been really important to the work of the ICSR housing vertical is historical context,” says Peko Hosoi, a professor of mechanical engineering and mathematics who co-leads the ICSR Housing vertical with D’Ignazio. “We didn’t get to the place we are right now with housing in an instant. There’s a lot of things that have happened in the U.S. like redlining, predatory lending, and different ways of investing in infrastructure that add important contexts.”
“Quantitative methods are a great way to look across macroscale phenomena, but our team recognizes and values qualitative and participatory methods as well, to get a more grounded picture of what community needs really are and what kinds of innovations can bubble up from communities themselves,” D’Ignazio adds. “This is where the partnership with Camfield Estates comes in, which Nolen has been leading.”
Finding creative solutions
Before coming to MIT, Scruggs, a proud New Yorker, worked on housing issues while interning for his local congressperson, House Minority Leader Hakeem Jeffries. He called residents to discuss their housing concerns, learning about the affordability issues that were making it hard for lower- and middle-income families to find places to live.
“Having this behind-the-scenes experience set the stage for my involvement in Camfield,” Scruggs says, recalling his start at Camfield conducting participatory action research, meeting with Camfield seniors to discuss and capture their concerns.
Scruggs says the biggest issue they have been trying to tackle with Camfield is twofold: creating more space for new residents while also helping current residents achieve their end goal of homeownership.
“This speaks to some of the larger issues our group at ICSR is working on in terms of housing affordability,” he says. “With Camfield it is looking at where can people with Section 8 vouchers move, what limits do they have, and what barriers do they face — whether it’s through big tech systems, or individual preferences coming from landlords.”
Scruggs adds, “The discrimination those people face while trying to find a house, lock it down, talk to a bank, etc. — it can be very, very difficult and discouraging.” Scruggs says one attempt to combat this issue would be through hiring a caseworker to assist people through the process — one of many ideas that came from a Camfield collaboration with the FHLBank Affordable Housing Development Competition.
As part of the competition, the goal for Scruggs’s team was to help Camfield tenants understand all of their options and their potential trade-offs, so that in the end they can make informed decisions about what they want to do with their space.
“So often redevelopment schemes don’t ensure people can come back.” Scruggs says. “There are specific design proposals being made to ensure that the structure of people’s lifestyles wouldn’t be disrupted.”
Scruggs says that tentative recommendations discussed with tenant association president Paulette Ford include replacing the community center with a high-rise development that would increase the number of units available.
“I think they are thinking really creatively about their options,” Hosoi says. “Paulette Ford, and her mother before her, have always referred to Camfield as a ‘hand up,’ with the idea that people come to Camfield to live until they can afford a home of their own locally.”
Scruggs’s other partnership with Camfield involves working with MIT undergraduate Amelie Nagle as part of the Undergraduate Research Opportunities Program to create programing that will teach computer design and coding to Camfield community kids — in the very TechLab that goes back to MIT and Camfield’s first collaboration.
“Nolen has a real commitment to community-led knowledge production,” says D’Ignazio. “It has been a pleasure to work with him and see how he takes all his urban planning skills (GIS, mapping, urban design, photography, and more) to work in respectful ways that foreground community innovation.”
She adds: “We are hopeful that the process will yield some high-quality architectural and planning ideas, and help Camfield take the next step towards realizing their innovative vision.”
Must-know insights when navigating the CISO career path – CyberTalk
EXECUTIVE SUMMARY:
The CISO career path is as exciting as it is fraught with perils. Modern CISOs exist at the intersection of technology, security and business strategy. The stakes are high and the simplest of initiatives can easily command commendation or crumble and collapse, ending in highly visible, catastrophic failures.
Succeeding within a CISO role requires a unique skill set and a unique blend of industry perspectives. In this article, we’ll highlight essential approaches for both aspiring and seasoned CISOs to pursue in setting themselves up for success.
CISO career path insights
Regardless of where you are along your CISO career path, enrich your everyday with these pragmatic insights. Ensure that you maintain and emphasize:
1. Agility in an evolving landscape
Cyber threats and technologies evolve at a mind-bending pace. For instance, as artificial intelligence and deepfake technologies are becoming increasingly prevalent, hackers are identifying new tactics that enable them to leverage the tools to disrupt new targets, at-scale. To that effect, enterprise CISOs need to adapt in conjunction with trends — all the while, taking resource availability and changing business needs into consideration.
2. Data-driven decision-making
As a CISO, you’re not only a guardian of data; you’re also a steward of resources. In turn, it’s imperative to communicate the return on investment (ROI) of security initiatives to senior management and stakeholders. Showcase how security measures have not only protected assets, but how they have also contributed to compliance and have positively shaped other aspects of the business.
3. Strategic communication
CISOs must be able to translate technical jargon into language that non-technical stakeholders can grasp. The ability to articulate the utility of security investments, corresponding risks and risks associated with lack of action is critical. It means a higher probability of gaining support and the resources required to truly advance security.
4. Cross-functional partnerships
Strong CISOs work cross-functionally with other departments, including IT, the legal department, and human resources, among others. In so doing, CISOs help ensure that cyber security initiatives are integrated into the fabric of the organization, rather than languishing as isolated efforts. This approach also increases overall business resilience.
5. Continuous learning
Ensure that you’re a member of any and all relevant information security trade associations and training organizations. For instance, the International Society of Forensic Computer Examiners (ISFCE) and The Scientific Working Group on Digital Evidence (SWGDE) can serve as good starting points. See a comprehensive list of cyber security industry associations here.
In addition to formal trade group participation, CISOs should maintain less formal channels for ongoing education purposes. CISOs should pursue industry publications, attend webinars, participate in cyber security conferences, and make connections with other people. For cyber security professionals, staying updated on emerging threats, technologies and regulations is a non-negotiable.
Further information
A savvy CISO not only secures networks and workloads, but also secures their own future. With that in mind, aim for personal growth, work to achieve extraordinary outcomes, and become an inspiring leader who can guide the next generation through effective CISO career path development.
For more CISO career path insights, please see our past coverage. Lastly, discover more timely insights and analyses when you sign up for the cybertalk.org newsletter.
MIT scientists learn how to control muscles with light
For people with paralysis or amputation, neuroprosthetic systems that artificially stimulate muscle contraction with electrical current can help them regain limb function. However, despite many years of research, this type of prosthesis is not widely used because it leads to rapid muscle fatigue and poor control.
MIT researchers have developed a new approach that they hope could someday offer better muscle control with less fatigue. Instead of using electricity to stimulate muscles, they used light. In a study in mice, the researchers showed that this optogenetic technique offers more precise muscle control, along with a dramatic decrease in fatigue.
“It turns out that by using light, through optogenetics, one can control muscle more naturally. In terms of clinical application, this type of interface could have very broad utility,” says Hugh Herr, a professor of media arts and sciences, co-director of the K. Lisa Yang Center for Bionics at MIT, and an associate member of MIT’s McGovern Institute for Brain Research.
Optogenetics is a method based on genetically engineering cells to express light-sensitive proteins, which allows researchers to control activity of those cells by exposing them to light. This approach is currently not feasible in humans, but Herr, MIT graduate student Guillermo Herrera-Arcos, and their colleagues at the K. Lisa Yang Center for Bionics are now working on ways to deliver light-sensitive proteins safely and effectively into human tissue.
Herr is the senior author of the study, which appears today in Science Robotics. Herrera-Arcos is the lead author of the paper.
Optogenetic control
For decades, researchers have been exploring the use of functional electrical stimulation (FES) to control muscles in the body. This method involves implanting electrodes that stimulate nerve fibers, causing a muscle to contract. However, this stimulation tends to activate the entire muscle at once, which is not the way that the human body naturally controls muscle contraction.
“Humans have this incredible control fidelity that is achieved by a natural recruitment of the muscle, where small motor units, then moderate-sized, then large motor units are recruited, in that order, as signal strength is increased,” Herr says. “With FES, when you artificially blast the muscle with electricity, the largest units are recruited first. So, as you increase signal, you get no force at the beginning, and then suddenly you get too much force.”
This large force not only makes it harder to achieve fine muscle control, it also wears out the muscle quickly, within five or 10 minutes.
The MIT team wanted to see if they could replace that entire interface with something different. Instead of electrodes, they decided to try controlling muscle contraction using optical molecular machines via optogenetics.
Using mice as an animal model, the researchers compared the amount of muscle force they could generate using the traditional FES approach with forces generated by their optogenetic method. For the optogenetic studies, they used mice that had already been genetically engineered to express a light-sensitive protein called channelrhodopsin-2. They implanted a small light source near the tibial nerve, which controls muscles of the lower leg.
The researchers measured muscle force as they gradually increased the amount of light stimulation, and found that, unlike FES stimulation, optogenetic control produced a steady, gradual increase in contraction of the muscle.
“As we change the optical stimulation that we deliver to the nerve, we can proportionally, in an almost linear way, control the force of the muscle. This is similar to how the signals from our brain control our muscles. Because of this, it becomes easier to control the muscle compared with electrical stimulation,” Herrera-Arcos says.
Fatigue resistance
Using data from those experiments, the researchers created a mathematical model of optogenetic muscle control. This model relates the amount of light going into the system to the output of the muscle (how much force is generated).
This mathematical model allowed the researchers to design a closed-loop controller. In this type of system, the controller delivers a stimulatory signal, and after the muscle contracts, a sensor can detect how much force the muscle is exerting. This information is sent back to the controller, which calculates if, and how much, the light stimulation needs to be adjusted to reach the desired force.
Using this type of control, the researchers found that muscles could be stimulated for more than an hour before fatiguing, while muscles became fatigued after only 15 minutes using FES stimulation.
One hurdle the researchers are now working to overcome is how to safely deliver light-sensitive proteins into human tissue. Several years ago, Herr’s lab reported that in rats, these proteins can trigger an immune response that inactivates the proteins and could also lead to muscle atrophy and cell death.
“A key objective of the K. Lisa Yang Center for Bionics is to solve that problem,” Herr says. “A multipronged effort is underway to design new light-sensitive proteins, and strategies to deliver them, without triggering an immune response.”
As additional steps toward reaching human patients, Herr’s lab is also working on new sensors that can be used to measure muscle force and length, as well as new ways to implant the light source. If successful, the researchers hope their strategy could benefit people who have experienced strokes, limb amputation, and spinal cord injuries, as well as others who have impaired ability to control their limbs.
“This could lead to a minimally invasive strategy that would change the game in terms of clinical care for persons suffering from limb pathology,” Herr says.
The research was funded by the K. Lisa Yang Center for Bionics at MIT.
Using wobbling stellar material, astronomers measure the spin of a supermassive black hole for the first time
Astronomers at MIT, NASA, and elsewhere have a new way to measure how fast a black hole spins, by using the wobbly aftermath from its stellar feasting.
The method takes advantage of a black hole tidal disruption event — a blazingly bright moment when a black hole exerts tides on a passing star and rips it to shreds. As the star is disrupted by the black hole’s immense tidal forces, half of the star is blown away, while the other half is flung around the black hole, generating an intensely hot accretion disk of rotating stellar material.
The MIT-led team has shown that the wobble of the newly created accretion disk is key to working out the central black hole’s inherent spin.
In a study appearing today in Nature, the astronomers report that they have measured the spin of a nearby supermassive black hole by tracking the pattern of X-ray flashes that the black hole produced immediately following a tidal disruption event. The team followed the flashes over several months and determined that they were likely a signal of a bright-hot accretion disk that wobbled back and forth as it was pushed and pulled by the black hole’s own spin.
By tracking how the disk’s wobble changed over time, the scientists could work out how much the disk was being affected by the black hole’s spin, and in turn, how fast the black hole itself was spinning. Their analysis showed that the black hole was spinning at less than 25 percent the speed of light — relatively slow, as black holes go.
The study’s lead author, MIT Research Scientist Dheeraj “DJ” Pasham, says the new method could be used to gauge the spins of hundreds of black holes in the local universe in the coming years. If scientists can survey the spins of many nearby black holes, they can start to understand how the gravitational giants evolved over the history of the universe.
“By studying several systems in the coming years with this method, astronomers can estimate the overall distribution of black hole spins and understand the longstanding question of how they evolve over time,” says Pasham, who is a member of MIT’s Kavli Institute for Astrophysics and Space Research.
The study’s co-authors include collaborators from a number of institutions, including NASA, Masaryk University in the Czech Republic, the University of Leeds, the University of Syracuse, Tel Aviv University, the Polish Academy of Sciences, and elsewhere.
Shredded heat
Every black hole has an inherent spin that has been shaped by its cosmic encounters over time. If, for instance, a black hole has grown mostly through accretion — brief instances when some material falls onto the disk, this causes the black hole to spin up to quite high speeds. In contrast, if a black hole grows mostly by merging with other black holes, each merger could slow things down as one black hole’s spin meets up against the spin of the other.
As a black hole spins, it drags the surrounding space-time around with it. This drag effect is an example of Lense-Thirring precession, a longstanding theory that describes the ways in which extremely strong gravitational fields, such as those generated by a black hole, can pull on the surrounding space and time. Normally, this effect would not be obvious around black holes, as the massive objects emit no light.
But in recent years, physicists have proposed that, in instances such as during a tidal disruption event, or TDE, scientists might have a chance to track the light from stellar debris as it is dragged around. Then, they might hope to measure the black hole’s spin.
In particular, during a TDE, scientists predict that a star may fall onto a black hole from any direction, generating a disk of white-hot, shredded material that could be tilted, or misaligned, with respect to the black hole’s spin. (Imagine the accretion disk as a tilted donut that is spinning around a donut hole that has its own, separate spin.) As the disk encounters the black hole’s spin, it wobbles as the black hole pulls it into alignment. Eventually, the wobbling subsides as the disk settles into the black hole’s spin. Scientists predicted that a TDE’s wobbling disk should therefore be a measurable signature of the black hole’s spin.
“But the key was to have the right observations,” Pasham says. “The only way you can do this is, as soon as a tidal disruption event goes off, you need to get a telescope to look at this object continuously, for a very long time, so you can probe all kinds of timescales, from minutes to months.”
A high-cadence catch
For the past five years, Pasham has looked for tidal disruption events that are bright enough, and near enough, to quickly follow up and track for signs of Lense-Thirring precession. In February of 2020, he and his colleagues got lucky, with the detection of AT2020ocn, a bright flash, emanating from a galaxy about a billion light years away, that was initially spotted in the optical band by the Zwicky Transient Facility.
From the optical data, the flash appeared to be the first moments following a TDE. Being both bright and relatively close by, Pasham suspected the TDE might be the ideal candidate to look for signs of disk wobbling, and possibly measure the spin of the black hole at the host galaxy’s center. But for that, he would need much more data.
“We needed quick and high-cadence data,” Pasham says. “The key was to catch this early on because this precession, or wobble, should only be present early on. Any later, and the disk would not wobble anymore.”
The team discovered that NASA’s NICER telescope was able to catch the TDE and continuously keep an eye on it over months at a time. NICER — an abbreviation for Neutron star Interior Composition ExploreR — is an X-ray telescope on the International Space Station that measures X-ray radiation around black holes and other extreme gravitational objects.
Pasham and his colleagues looked through NICER’s observations of AT2020ocn over 200 days following the initial detection of the tidal disruption event. They discovered that the event emitted X-rays that appeared to peak every 15 days, for several cycles, before eventually petering out. They interpreted the peaks as times when the TDE’s accretion disk wobbled face-on, emitting X-rays directly toward NICER’s telescope, before wobbling away as it continued to emit X-rays (similar to waving a flashlight toward and away from someone every 15 days).
The researchers took this pattern of wobbling and worked it into the original theory for Lense-Thirring precession. Based on estimates of the black hole’s mass, and that of the disrupted star, they were able to come up with an estimate for the black hole’s spin — less than 25 percent the speed of light.
Their results mark the first time that scientists have used observations of a wobbling disk following a tidal disruption event to estimate the spin of a black hole.
“Black holes are fascinating objects and the flows of material that we see falling onto them can generate some of the most luminous events in the universe,” says study co-author Chris Nixon, associate professor of theoretical physics at the University of Leeds. “While there is a lot we still don’t understand, there are amazing observational facilities that keep surprising us and generating new avenues to explore. This event is one of those surprises.”
As new telescopes such as the Rubin Observatory come online in the coming years, Pasham foresees more opportunities to pin down black hole spins.
“The spin of a supermassive black hole tells you about the history of that black hole,” Pasham says. “Even if a small fraction of those that Rubin captures have this kind of signal, we now have a way to measure the spins of hundreds of TDEs. Then we could make a big statement about how black holes evolve over the age of the universe.”
This research was funded, in part, by NASA and the European Space Agency.
Adhesive coatings can prevent scarring around medical implants
When medical devices such as pacemakers are implanted in the body, they usually provoke an immune response that leads to buildup of scar tissue around the implant. This scarring, known as fibrosis, can interfere with the devices’ function and may require them to be removed.
In an advance that could prevent that kind of device failure, MIT engineers have found a simple and general way to eliminate fibrosis by coating devices with a hydrogel adhesive. This adhesive binds the devices to tissue and prevents the immune system from attacking it.
“The dream of many research groups and companies is to implant something into the body that over the long term the body will not see, and the device can provide therapeutic or diagnostic functionality. Now we have such an ‘invisibility cloak,’ and this is very general: There’s no need for a drug, no need for a special polymer,” says Xuanhe Zhao, an MIT professor of mechanical engineering and of civil and environmental engineering.
The adhesive that the researchers used in this study is made from cross-linked polymers called hydrogels, and is similar to a surgical tape they previously developed to help seal internal wounds. Other types of hydrogel adhesives can also protect against fibrosis, the researchers found, and they believe this approach could be used for not only pacemakers but also sensors or devices that deliver drugs or therapeutic cells.
Zhao and Hyunwoo Yuk SM ’16, PhD ’21, a former MIT research scientist who is now the chief technology officer at SanaHeal, are the senior authors of the study, which appears today in Nature. MIT postdoc Jingjing Wu is the lead author of the paper.
Preventing fibrosis
In recent years, Zhao’s lab has developed adhesives for a variety of medical applications, including double-sided and single-sided tapes that could be used to heal surgical incisions or internal injuries. These adhesives work by rapidly absorbing water from wet tissues, using polyacrylic acid, an absorbent material used in diapers. Once the water is cleared, chemical groups called NHS esters embedded in the polyacrylic acid form strong bonds with proteins at the tissue surface. This process takes about five seconds.
Several years ago, Zhao and Yuk began exploring whether this kind of adhesive could also help keep medical implants in place and prevent fibrosis from occurring.
To test this idea, Wu coated polyurethane devices with their adhesive and implanted them on the abdominal wall, colon, stomach, lung, or heart of rats. Weeks later, they removed the device and found that there was no visible scar tissue. Additional tests with other animal models showed the same thing: Wherever the adhesive-coated devices were implanted, fibrosis did not occur, for up to three months.
“This work really has identified a very general strategy, not only for one animal model, one organ, or one application,” Wu says. “Across all of these animal models, we have consistent, reproducible results without any observable fibrotic capsule.”
Using bulk RNA sequencing and fluorescent imaging, the researchers analyzed the animals’ immune response and found that when devices with adhesive coatings were first implanted, immune cells such as neutrophils began to infiltrate the area. However, the attacks quickly quenched out before any scar tissue could form.
“For the adhered devices, there is an acute inflammatory response because it is a foreign material,” Yuk says. “However, very quickly that inflammatory response decayed, and then from that point you do not have this fibrosis formation.”
One application for this adhesive could be coatings for epicardial pacemakers — devices that are placed on the heart to help control the heart rate. The wires that contact the heart often become fibrotic, but the MIT team found that when they implanted adhesive-coated wires in rats, they remained functional for at least three months, with no scar tissue formation.
“The formation of fibrotic tissue at the interface between implanted medical devices and the target tissue is a longstanding problem that routinely causes failure of the device. The demonstration that robust adhesion between the device and the tissue obviates fibrotic tissue formation is an important observation that has many potential applications in the medical device space,” says David Mooney, a professor of bioengineering at Harvard University, who was not involved in the study.
Mechanical cues
The researchers also tested a hydrogel adhesive that includes chitosan, a naturally occurring polysaccharide, and found that this adhesive also eliminated fibrosis in animal studies. However, two commercially available tissue adhesives that they tested did not show this antifibrotic effect because the commercially available adhesives eventually detached from the tissue and allowed the immune system to attack.
In another experiment, the researchers coated implants in hydrogel adhesives but then soaked them in a solution that removed the polymers’ adhesive properties, while keeping their overall chemical structure the same. After being implanted in the body, where they were held in place by sutures, fibrotic scarring occurred. This suggests that there is something about the mechanical interaction between the adhesive and the tissue that prevents the immune system from attacking, the researchers say.
“Previous research in immunology has been focused on chemistry and biochemistry, but mechanics and physics may play equivalent roles, and we should pay attention to those mechanical and physical cues in immunological responses,” says Zhao, who now plans to further investigate how those mechanical cues affect the immune system.
Yuk, Zhao, and others have started a company called SanaHeal, which is now working on further developing tissue adhesives for medical applications.
“As a team, we are interested in reporting this to the community and sparking speculation and imagination as to where this can go,” Yuk says. “There are so many scenarios in which people want to interface with foreign or manmade material in the body, like implantable devices, drug depots, or cell depots.”
The research was funded by the National Institutes of Health and the National Science Foundation.
The origin of the sun’s magnetic field could lie close to its surface
The sun’s surface is a brilliant display of sunspots and flares driven by the solar magnetic field, which is internally generated through a process called dynamo action. Astrophysicists have assumed that the sun’s field is generated deep within the star. But an MIT study finds that the sun’s activity may be shaped by a much shallower process.
In a paper appearing today in Nature, researchers at MIT, the University of Edinburgh, and elsewhere find that the sun’s magnetic field could arise from instabilities within the sun’s outermost layers.
The team generated a precise model of the sun’s surface and found that when they simulated certain perturbations, or changes in the flow of plasma (ionized gas) within the top 5 to 10 percent of the sun, these surface changes were enough to generate realistic magnetic field patterns, with similar characteristics to what astronomers have observed on the sun. In contrast, their simulations in deeper layers produced less realistic solar activity.
The findings suggest that sunspots and flares could be a product of a shallow magnetic field, rather than a field that originates deeper in the sun, as scientists had largely assumed.
“The features we see when looking at the sun, like the corona that many people saw during the recent solar eclipse, sunspots, and solar flares, are all associated with the sun’s magnetic field,” says study author Keaton Burns, a research scientist in MIT’s Department of Mathematics. “We show that isolated perturbations near the sun’s surface, far from the deeper layers, can grow over time to potentially produce the magnetic structures we see.”
If the sun’s magnetic field does in fact arise from its outermost layers, this might give scientists a better chance at forecasting flares and geomagnetic storms that have the potential to damage satellites and telecommunications systems.
“We know the dynamo acts like a giant clock with many complex interacting parts,” says co-author Geoffrey Vasil, a researcher at the University of Edinburgh. “But we don’t know many of the pieces or how they fit together. This new idea of how the solar dynamo starts is essential to understanding and predicting it.”
The study’s co-authors also include Daniel Lecoanet and Kyle Augustson of Northwestern University, Jeffrey Oishi of Bates College, Benjamin Brown and Keith Julien of the University of Colorado at Boulder, and Nicholas Brummell of the University of California at Santa Cruz.
Flow zone
The sun is a white-hot ball of plasma that’s boiling on its surface. This boiling region is called the “convection zone,” where layers and plumes of plasma roil and flow. The convection zone comprises the top one-third of the sun’s radius and stretches about 200,000 kilometers below the surface.
“One of the basic ideas for how to start a dynamo is that you need a region where there’s a lot of plasma moving past other plasma, and that shearing motion converts kinetic energy into magnetic energy,” Burns explains. “People had thought that the sun’s magnetic field is created by the motions at the very bottom of the convection zone.”
To pin down exactly where the sun’s magnetic field originates, other scientists have used large three-dimensional simulations to try to solve for the flow of plasma throughout the many layers of the sun’s interior. “Those simulations require millions of hours on national supercomputing facilities, but what they produce is still nowhere near as turbulent as the actual sun,” Burns says.
Rather than simulating the complex flow of plasma throughout the entire body of the sun, Burns and his colleagues wondered whether studying the stability of plasma flow near the surface might be enough to explain the origins of the dynamo process.
To explore this idea, the team first used data from the field of “helioseismology,” where scientists use observed vibrations on the sun’s surface to determine the average structure and flow of plasma beneath the surface.
“If you take a video of a drum and watch how it vibrates in slow motion, you can work out the drumhead’s shape and stiffness from the vibrational modes,” Burns says. “Similarly, we can use vibrations that we see on the solar surface to infer the average structure on the inside.”
Solar onion
For their new study, the researchers collected models of the sun’s structure from helioseismic observations. “These average flows look sort like an onion, with different layers of plasma rotating past each other,” Burns explains. “Then we ask: Are there perturbations, or tiny changes in the flow of plasma, that we could superimpose on top of this average structure, that might grow to cause the sun’s magnetic field?”
To look for such patterns, the team utilized the Dedalus Project — a numerical framework that Burns developed that can simulate many types of fluid flows with high precision. The code has been applied to a wide range of problems, from modeling the dynamics inside individual cells, to ocean and atmospheric circulations.
“My collaborators have been thinking about the solar magnetism problem for years, and the capabilities of Dedalus have now reached the point where we could address it,” Burns says.
The team developed algorithms that they incorporated into Dedalus to find self-reinforcing changes in the sun’s average surface flows. The algorithm discovered new patterns that could grow and result in realistic solar activity. In particular, the team found patterns that match the locations and timescales of sunspots that have been have observed by astronomers since Galileo in 1612.
Sunspots are transient features on the surface of the sun that are thought to be shaped by the sun’s magnetic field. These relatively cooler regions appear as dark spots in relation to the rest of the sun’s white-hot surface. Astronomers have long observed that sunspots occur in a cyclical pattern, growing and receding every 11 years, and generally gravitating around the equator, rather than near the poles.
In the team’s simulations, they found that certain changes in the flow of plasma, within just the top 5 to 10 percent of the sun’s surface layers, were enough to generate magnetic structures in the same regions. In contrast, changes in deeper layers produce less realistic solar fields that are concentrated near the poles, rather than near the equator.
The team was motivated to take a closer look at flow patterns near the surface as conditions there resembled the unstable plasma flows in entirely different systems: the accretion disks around black holes. Accretion disks are massive disks of gas and stellar dust that rotate in towards a black hole, driven by the “magnetorotational instability,” which generates turbulence in the flow and causes it to fall inward.
Burns and his colleagues suspected that a similar phenomena is at play in the sun, and that the magnetorotational instability in the sun’s outermost layers could be the first step in generating the sun’s magnetic field.
“I think this result may be controversial,” he ventures. “Most of the community has been focused on finding dynamo action deep in the sun. Now we’re showing there’s a different mechanism that seems to be a better match to observations.” Burns says that the team is continuing to study if the new surface field patterns can generate individual sunspots and the full 11-year solar cycle.
This research was supported, in part, by NASA.
Study: Under extreme impacts, metals get stronger when heated
Metals get softer when they are heated, which is how blacksmiths can form iron into complex shapes by heating it red hot. And anyone who compares a copper wire with a steel coat hanger will quickly discern that copper is much more pliable than steel.
But scientists at MIT have discovered that when metal is struck by an object moving at a super high velocity, the opposite happens: The hotter the metal, the stronger it is. Under those conditions, which put extreme stress on the metal, copper can actually be just as strong as steel. The new discovery could lead to new approaches to designing materials for extreme environments, such as shields that protect spacecraft or hypersonic aircraft, or equipment for high-speed manufacturing processes.
The findings are described in a paper appearing today in the journal Nature, by Ian Dowding, an MIT graduate student, and Christopher Schuh, former head of MIT’s Department of Materials Science and Engineering, now dean of engineering at Northwestern University and visiting professor at MIT.
The new finding, the authors write, “is counterintuitive and at odds with decades of studies in less extreme conditions.” The unexpected results could affect a variety of applications because the extreme velocities involved in these impacts occur routinely in meteorite impacts on spacecraft in orbit and in high-speed machining operations used in manufacturing, sandblasting, and some additive manufacturing (3D printing) processes.
The experiments the researchers used to find this effect involved shooting tiny particles of sapphire, just millionths of a meter across, at flat sheets of metal. Propelled by laser beams, the particles reached high velocities, on the order of a few hundred meters per second. While other researchers have occasionally done experiments at similarly high velocities, they have tended to use larger impactors, at the scale of centimeters or larger. Because these larger impacts were dominated by effects of the shock of the impact, there was no way to separate out the mechanical and thermal effects.
The tiny particles in the new study don’t create a significant pressure wave when they hit the target. But it has taken a decade of research at MIT to develop methods of propelling such microscopic particles at such high velocities. “We’ve taken advantage of that,” Schuh says, along with other new techniques for observing the high-speed impact itself.
The team used extremely high-speed cameras “to watch the particles as they come in and as they fly away,” he says. As the particles bounce off the surface, the difference between the incoming and outgoing velocities “tells you how much energy was deposited” into the target, which is an indicator of the surface strength.
The tiny particles they used were made of alumina, or sapphire, and are “very hard,” Dowding says. At 10 to 20 microns (millionths of a meter) across, these are between one-tenth and one-fifth of the thickness of a human hair. When the launchpad behind those particles is hit by a laser beam, part of the material vaporizes, creating a jet of vapor that propels the particle in the opposite direction.
The researchers shot the particles at samples of copper, titanium, and gold, and they expect their results should apply to other metals as well. They say their data provide the first direct experimental evidence for this anomalous thermal effect of increased strength with greater heat, although hints of such an effect had been reported before.
The surprising effect appears to result from the way the orderly arrays of atoms that make up the crystalline structure of metals move under different conditions, according to the researchers’ analysis. They show that there are three separate effects governing how metal deforms under stress, and while two of these follow the predicted trajectory of increasing deformation at higher temperatures, it is the third effect, called drag strengthening, that reverses its effect when the deformation rate crosses a certain threshold.
Beyond this crossover point, the higher temperature increases the activity of phonons — waves of sound or heat — within the material, and these phonons interact with dislocations in the crystalline lattice in a way that limits their ability to slip and deform. The effect increases with increased impact speed and temperature, Dowding says, so that “the faster you go, the less the dislocations are able to respond.”
Of course, at some point the increased temperature will begin to melt the metal, and at that point the effect will reverse again and lead to softening. “There will be a limit” to this strengthening effect, Dowding says, “but we don’t know what it is.”
The findings could lead to different choices of materials when designing devices that may encounter such extreme stresses, Schuh says. For example, metals that may ordinarily be much weaker, but that are less expensive or easier to process, might be useful in situations where nobody would have thought to use them before.
The extreme conditions the researchers studied are not confined to spacecraft or extreme manufacturing methods. “If you are flying a helicopter in a sandstorm, a lot of these sand particles will reach high velocities as they hit the blades,” Dowding says, and under desert conditions they may reach the high temperatures where these hardening effects kick in.
The techniques the researchers used to uncover this phenomenon could be applied to a variety of other materials and situations, including other metals and alloys. Designing materials to be used in extreme conditions by simply extrapolating from known properties at less extreme conditions could lead to seriously mistaken expectations about how materials will behave under extreme stresses, they say.
The research was supported by the U.S. Department of Energy.
Hunt: Showdown’s New-Gen Console Update Arrives In August, Rendering Last-Gen Versions Unplayable
Crytek has announced the release date for Hunt: Showdown’s new-gen update, which will also conclude support for the current console versions. This update was first announced last September and will essentially force last-gen players to migrate to current consoles to continue playing the popular shooter.
In a developer update, general manager David Fifield announced that the CryEngine 5.11 Update will go live on August 15. This update is treated as a “significant relaunch” that brings native PS5/Xbox Series X/S support along with a host of technical improvements. However, it also means the PS4 and Xbox One versions will become unplayable.
That means these players must upgrade to current hardware to continue playing their copies of the game. Crytek assures these players that if they decide to upgrade, player accounts, entitlements, and all owned DLC will transfer to the new-gen version for no extra cost.
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In addition to technical improvements, the 5.11 Update also introduces a new map and biome. In the months leading to 5.11’s launch, Crytek plans to address community and survey feedback. That includes improved reporting systems to address cheating and toxic player behavior, design reworks tackling hunter revival, health chunks, restorations, burning down hunters, and reducing stalemates. The game is also getting a new user interface, and Crytek will continue evolving the game’s recruitment and prestige progression requirements.
Hunt: Showdown first launched for Xbox and PC in 2019, with the PS4 version arriving in 2020. The PvPvE first-person shooter is set in 1865 Louisiana as players, either alone or with two or three friends, hunt supernatural bounties in the bayou while fending off other player-controlled bounty hunters.
For more on Crytek, you can read about the studio’s next big project, Crysis 4.
Adobe introduces AI-powered eraser to Lightroom
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