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Monday, October 2nd, 2017
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| 10:22a |
Fast-moving magnetic particles could enable new form of data storage New research has shown that an exotic kind of magnetic behavior discovered just a few years ago holds great promise as a way of storing data — one that could overcome fundamental limits that might otherwise be signaling the end of “Moore’s Law,” which describes the ongoing improvements in computation and data storage over recent decades.
Rather than reading and writing data one bit at a time by changing the orientation of magnetized particles on a surface, as today’s magnetic disks do, the new system would make use of tiny disturbances in magnetic orientation, which have been dubbed “skyrmions.” These virtual particles, which occur on a thin metallic film sandwiched against a film of different metal, can be manipulated and controlled using electric fields, and can store data for long periods without the need for further energy input.
In 2016, a team led by MIT associate professor of materials science and engineering Geoffrey Beach documented the existence of skyrmions, but the particles’ locations on a surface were entirely random. Now, Beach has collaborated with others to demonstrate experimentally for the first time that they can create these particles at will in specific locations, which is the next key requirement for using them in a data storage system. An efficient system for reading that data will also be needed to create a commercializable system.
The new findings are reported this week in the journal Nature Nanotechnology, in a paper by Beach, MIT postdoc Felix Buettner, and graduate student Ivan Lemesh, and 10 others at MIT and in Germany.
The system focuses on the boundary region between atoms whose magnetic poles are pointing in one direction and those with poles pointing the other way. This boundary region can move back and forth within the magnetic material, Beach says. What he and his team found four years ago was that these boundary regions could be controlled by placing a second sheet of nonmagnetic heavy metal very close to the magnetic layer. The nonmagnetic layer can then influence the magnetic one, with electric fields in the nonmagnetic layer pushing around the magnetic domains in the magnetic layer. Skyrmions are little swirls of magnetic orientation within these layers, Beach adds.
The key to being able to create skyrmions at will in particular locations, it turns out, lay in material defects. By introducing a particular kind of defect in the magnetic layer, the skyrmions become pinned to specific locations on the surface, the team found. Those surfaces with intentional defects can then be used as a controllable writing surface for data encoded in the skyrmions. The team realized that instead of being a problem, the defects in the material could actually be beneficial.
“One of the biggest missing pieces” needed to make skyrmions a practical data-storage medium, Beach says, was a reliable way to create them when and where they were needed. “So this is a significant breakthrough,” he explains, thanks to work by Buettner and Lemesh, the paper’s lead authors. “What they discovered was a very fast and efficient way to write” such formations.
Because the skyrmions, basically little eddies of magnetism, are incredibly stable to external perturbations, unlike the individual magnetic poles in a conventional magnetic storage device, data can be stored using only a tiny area of the magnetic surface — perhaps just a few atoms across. That means that vastly more data could be written onto a surface of a given size. That’s an important quality, Beach explains, because conventional magnetic systems are now reaching limits set by the basic physics of their materials, potentially bringing to a halt the steady improvement of storage capacities that are the basis for Moore’s Law. The new system, once perfected, could provide a way to continue that progress toward ever-denser data storage, he says.
The system also potentially could encode data at very high speeds, making it efficient not only as a substitute for magnetic media such as hard discs, but even for the much faster memory systems used in Random Access Memory (RAM) for computation.
But what is still lacking is an effective way to read out the data once it has been stored. This can be done now using sophisticated X-ray magnetic spectroscopy, but that requires equipment too complex and expensive to be part of a practical computer memory system. The researchers plan to explore better ways of getting the information back out, which could be practical to manufacture at scale.
The X-ray spectrograph is “like a microscope without lenses,” Buettner explains, so the image is reconstructed mathematically from the collected data, rather than physically by bending light beams using lenses. Lenses for X-rays exist, but they are very complex, and cost $40,000 to $50,000 apiece, he says.
But an alternative way of reading the data may be possible, using an additional metal layer added to the other layers. By creating a particular texture on this added layer, it may be possible to detect differences in the layer’s electrical resistance depending on whether a skyrmion is present or not in the adjacent layer. “There’s no question it would work,” Buettner says, it’s just a matter of figuring out the needed engineering development. The team is pursuing this and other possible strategies to address the readout question.
The team also included researchers at the Max Born Institute and the Institute of Optics and Atomic Physics, both in Berlin; the Institute for Laser Technologies in Medicine and Metrology at the University of Ulm, in Germany; and the Deutches Elektroniken-Syncrotron (DESY), in Hamburg. The work was supported by the U.S. Department of Energy and the German Science Foundation. | | 11:27a |
Michael Rosbash PhD ’71 wins Nobel Prize in physiology or medicine Michael Rosbash, who earned his PhD from MIT in 1971, will share the 2017 Nobel Prize in physiology or medicine, the Nobel Committee announced this morning in Stockholm.
Rosbash, now a professor of biology at Brandeis University, shares the prize with Jeffrey C. Hall of the University of Maine and Michael W. Young of Rockefeller University. The scientists were honored for “their discoveries of molecular mechanisms controlling the circadian rhythm.”
Circadian rhythms help living organisms adapt their biological activities to the normal 24-hour cycle of light and darkness. These rhythms influence behavior, sleep, metabolism, body temperature, and many other biological functions.
In 1984, Rosbash, Hall, and Young isolated a gene that regulates these daily rhythms in fruit flies. This gene, known as period, encodes a protein that accumulates during the night and is degraded during the day. Further work revealed that this protein inhibits the gene that encodes it, creating a negative feedback loop that is key to generating continuous oscillations.
Since then, the three scientists have discovered several other genes necessary for maintaining circadian cycles, and similar processes have been found in many other organisms, including humans.
Rosbash was born in Kansas City, Missouri, but grew up in Newton, Massachusetts. He earned his bachelor’s degree at Caltech before coming to MIT to pursue a PhD in biology. He has been on the faculty at Brandeis since 1974, and he is an investigator with the Howard Hughes Medical Institute and a member of the National Academy of Sciences. In 2013, Rosbash, Hall, and Young shared the Shaw Prize in Life Sciences and Medicine for their circadian clock research.
Rosbash is the 35th MIT alumnus to win a Nobel Prize, and the 88th MIT-connected winner of the prize. | | 11:40a |
New target for treating “undruggable” lung cancer Mutations in the KEAP1 gene could point the way to treating an aggressive form of lung cancer that is driven by “undruggable” mutations in the KRAS gene, according to a new study by MIT researchers.
KEAP1 mutations occur alongside KRAS mutations in about 17 percent of lung adenocarcinoma cases. Tyler Jacks, director of MIT’s Koch Institute for Integrative Cancer Research and co-senior author of the study, and his colleagues found that cancer cells with nonfunctioning KEAP1 genes are hungry for glutamine, an amino acid essential for protein synthesis and energy use. Starving these cells of glutamine may thus offer a way to treat cancers with both KRAS and KEAP1 mutations.
Indeed, small-molecule-based inhibitors of glutaminase, an enzyme crucial to glutamine metabolism, slowed cancer cell growth and led to smaller tumors overall in human lung adenocarcinoma cell lines and in tumors in mice with KEAP1 mutations, the researchers found.
The study offers a way to identify lung cancer patients who might respond well to drugs that block the work of glutaminase, says MIT graduate student Rodrigo Romero, a first author on the paper that appears in the Oct. 2 online edition of Nature Medicine.
“All cell lines that we have currently tested that are KEAP1-mutant — independent of their KRAS status — appear to be exquisitely sensitive to glutaminase inhibitors,” says Romero, a graduate student in Jacks’ lab, who participated in the MIT Summer Research Program (MSRP) as an undergraduate.
Hyperactivating the antioxidant response
Lung adenocarcinoma accounts for about 40 percent of U.S. lung cancers, and 15 to 30 percent of those cases contain a KRAS mutation. KRAS has been “notoriously difficult to inhibit” because the usual ways of blocking the KRAS protein’s interactions or interfering with the protein’s targets have fallen short, says Romero.
Lung cancers containing KRAS mutations often harbor other mutations, including KEAP1, which is the third most frequently mutated gene in lung adenocarcinoma. To find out more about how these co-mutations affect lung cancer progression, the MIT research team created KEAP1 mutations in mouse models of lung adenocarcinoma, using the CRISPR/Cas9 gene-editing system to target the gene.
The KEAP1 protein normally represses another protein called NRF2, which controls the activation of an antioxidant response that removes toxic, reactive oxygen species from cells. When the researchers disabled KEAP1 with loss-of-function mutations, NRF2 was able to accumulate and contribute to a “hyperactivation” of the antioxidant response.
Lung adenocarcinomas bearing the KEAP1 mutation may “take advantage of this [hyper-activation] to promote cellular growth or detoxify intracellular damaging agents,” Romero says.
In fact, when the researchers examined genes targeted by NRF2 across a sample of human lung adenocarcinoma tumors, they concluded that the expression of these genes was greater in advanced stage IV tumors, and that patients with such “up-regulated” NRF2 tumors had significantly worse survival rates than other lung adenocarcinoma patients.
Tumors hungry for glutamine
Romero and colleagues used CRISPR/Cas9 to learn more about other genetic interactions with KEAP1 mutants. Their screening demonstrated that lung cancer cells with KRAS and KEAP1 loss-of function mutations were more dependent than other cells on increased amounts of glutamine.
To learn whether this glutamine hunger could be a therapeutic vulnerability, the researchers tested two glutaminase inhibitors against the cancer cells, including one compound called CB-839 that is in phase I clinical trials for KRAS-mutant lung cancer. CB-839 slowed growth and kept tumors smaller than normal in lung adenocarcinoma with KEAP1 mutations, the researchers found.
Phase I clinical trials that treat KEAP1-mutant lung adenocarcinoma patients with a combination of CB-839 and the cancer immunotherapy drug nivolumab (Opdivo) are also underway, says Romero, who notes the MIT study might help identify patients who would be good candidates for these trials.
“There are also many clinical trials testing the efficacy of glutaminase inhibition in a variety of cancer types, independent of KRAS status. However, the results from these studies are still unclear,” Romero says.
Jacks emphasizes that his laboratory has and will continue to study several mutations beyond KEAP1 that may cooperate with KRAS in their mouse models of human lung adenocarcinoma. “The complexity of human cancer can be quite daunting,” he notes. “The genetic tools that we have assembled allow us to create models of many individual subtypes of the disease and in this way begin to define the exploitable vulnerabilities of each. The observed sensitivity of KEAP1 mutant tumors to glutaminase inhibitors is an important example of this approach. There will be more.”
Co-authors on the Nature Medicine paper include former Koch Institute postdoc Thales Papagiannakopoulos, now at New York University, and MIT professor of biology Matthew Vander Heiden. The research was funded by the Laura and Isaac Perlmutter Cancer Support Grant, the National Institutes of Health, and the Koch Institute Support Grant from the National Cancer Institute. | | 4:15p |
Presentation practice: Hurricanes to prosthetics The wind whipped down Massachusetts Ave. Torrents of rain pelleted the roof of the Zesiger Sports and Fitness Center. The remnants of Hurricane Jose circled above.
But dry inside the Johnson Ice Rink, mechanical engineering graduate student Sydney Sroka had a different hurricane on her mind. Data from 1997’s Hurricane Guillermo informed her research on improving hurricane intensity forecasts.
“The overwhelming majority of energy in a hurricane comes from warm seawater, which bubbles into sea spray because the wind is so fast,” Sroka explained, pointing to a figure of small water droplets. “The air temperature is mediated by these tiny drops of seaspray, that are affected by microphysics,” she added.
By analyzing and modeling the heat of these drops of water, she said she hopes that forecasters can make more accurate predictions about a hurricane’s strength.
Sroka was one of the over 70 graduate students participating in the annual Mechanical Engineering Research Exhibition (MERE). In its fourth year, MERE, which is hosted by the Department of Mechanical Engineering and the Graduate Association of Mechanical Engineers, gives mechanical engineering graduate students, Undergraduate Research Opportunities Program (UROP) participants, and postdocs a chance to present their work to alumni, faculty, and fellow students. Projects range from low-cost braille label makers to solar thermophotovoltaic systems and an in vitro intestinal organ model.
“I think it is very important community building event,” said Professor Nicholas Fang, MERE’s faculty advisor. “For our graduate students, this is a great opportunity to get to know each other. MERE is often their first exposure to other research activities in the department.”
MERE is more than just an opportunity for students to showcase the research they’re working on — one of its primary goals is to emphasize the importance of effective communication to a diverse audience.
The set-up is similar to a poster session at a scientific conference. Students stand in front of their posters and answer questions from attendees. At MERE, these attendees are mostly comprised of alumni and faculty, who serve as judges. The judges aren’t just interested in what kind of research these students are presenting, but how the students are presenting the research. This setup enables students the ability to practice and hone their presentation skills and prepare for upcoming conferences or qualifying exams.
“I presented last year and it was a great experience and opportunity to get useful feedback on my work,” said PhD candidate Arny Leroy, who presented this year on high performance incandescent lighting. “It’s helpful to practice presenting.”
Some students were able to exhibit live demos as a part of their presentation. During the first poster session, a robot designed to adhere to pedestrian rules whizzed around the attendees. The robot was part of Michael Everett’s research project. Meanwhile Rachel Hoffman was able to show attendees a scale model of the multi-track elevator system she is working on for e-commerce fulfillment centers.
After the judges’ marks were tallied this year’s winners were announced. The day was capped off with a keynote speech by former NASA astronaut Mike Massimino SM '88, PhD '92. Massimino chronicled his journey from his childhood on Long Island playing with an astronaut Snoopy toy, to his time as an MIT graduate student living in a small apartment in Central Square, and then finally his experience working on the Hubble Space Telescope as an astronaut.
The following students were honored by the judges:
Best Overall/Understanding: Sebastian Pattinson — “Printed mesh materials with locally tailored elasticity for compliant wearable and implantable devices.”
Highest Impact: Arny Leroy — “High performance incandescent lighting”
Most Excitement: Elise Strobach — “Optically Transparent, Thermally Insulating and Soundproofing (OTTIS) Aerogel for High-Efficiency Window Applications
Best UROP: Ryan Koeppen — “Controlling Physical Interaction: Humans Do Not Minimize Energy”
The runner-ups included Victor Prost, Vrushank Phadnis, Jerry Wang, Mohammad Farazmand, Sydney Sroka, Hyeon Yu Kim, Anoop Rajappan, Edward Burnell, Kevin Kung, and Cecile Chazot.
Those receiving honorable mention included Bethany Lettiere, Yi Huang, Abiodun Olaoye, Michael Everett, Bikram Bhatia, Xiaoyu Wu, Zheng Jie Tan, Andrew Bouma, Qifang Bao, Quantum Wei, Sahil Shah, and Yi Xue. |
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