News from www.caltech.eduhttps://www.caltech.edu/about/news2024-03-18T17:39:00.265152+00:00The Office of Strategic Communicationswww@caltech.eduCopyright © 2024 California Institute of TechnologyME 72 Takes to the Sky for Rousing Match of Quidd ... Airship Quadball2024-03-15T17:26:00+00:002024-03-18T17:39:00.265152+00:00https://www.caltech.edu/about/news/me72-takes-to-the-sky-for-rousing-match-of-quid-airship-quadball<p data-block-key="qu8g2">There were no brooms or bludgers in sight on the basketball court inside Caltech's Scott Brown Gymnasium on March 8, but it was hard not to think of everyone's favorite teenage wizard and his sporting pastime while watching the 39th annual ME 72 Engineering Design Competition. As onlookers cheered from the stands, remotely controlled blimps maneuvered through the air, scooped up shiny blue, floating balls, and sometimes sent them through goals raised 10 feet off the ground.</p><p data-block-key="i80ve">Every year, third-year mechanical engineering undergraduate students at Caltech take ME 72, a two-term, project-based course that culminates in the engineering design competition. The details of the challenge vary from year to year (previous students have been tasked with building <a href="/about/news/robots-make-big-splash-annual-engineering-competition">amphibious robots</a>, "<a href="/about/news/me72-live-and-in-person-once-more">SumoBots</a>," and <a href="/about/news/robots-duke-it-out-tank-wars-81623">robotic tanks</a>), but the competition always shows off the ingenuity and engineering capabilities of the student teams that spend hundreds of hours designing, building, testing, and reimagining their entries leading up to the course's big finale.</p><p data-block-key="3qpba">This year's challenge, dubbed "Airship Quadball," was the first aerial battle of the bots in the competition's history. The task—dreamed up by the course's advisor, Michael Mello (PhD '12), teaching professor of mechanical and civil engineering, and his teaching assistants—sounds simple enough: Design and build as many as three helium-filled, lighter-than-air vehicles to intercept neutrally buoyant balloons and push them through one of three goals on the other side of a court.</p><p data-block-key="5gmbb">In reality, every aspect of the task, including what material to use to make the airships, what shape to make them, and what hardware and electronics to use to maneuver them through the air, was extremely tricky.</p><p data-block-key="76p2u">"It's much harder than it looks. For the human eye, it is challenging to see a ball distantly and somehow remotely guide your balloon toward it," Mello says. "Then there is the buoyancy and weight restriction. You only get so much vertical lift force from helium. Every ounce matters, so the students had to make lots of decisions about what materials to use and what tradeoffs they were willing to make."</p><p data-block-key="c5qgv">The students worked in five teams with four or five members each—B.O.O.M. (Blimp Operations Of Mayhem), Las Aguilas Azules, Led Zeppelin, Mechromancers, and M.O.A.B. (Mother Of All Blimps). Beginning in the fall term, the students first attended orientation lectures and then began the design phase of their projects. By the end of that first term, each team had to complete a mobility milestone and show that one of its blimps could fly and be steered. Then came the big push during the 10 weeks of winter term when the teams repeatedly prototyped, tested, brainstormed, and made adjustments to arrive at the final products that eventually took to the air in Brown Gym.</p><p data-block-key="a1fl8">After one team discovered an excellent heat-sealable metallized film (sheets of a mylar-like material that can be ironed together) all the teams ended up using it to make the balloon "envelope," the blimp part of their airships. All the teams also used thin, flexible carbon fiber rods or balsa wood to create and integrate a frame structure to their blimp. But beyond these similarities, each team came up with its own design and method of maneuvering.</p><p data-block-key="83qb1">"It's really remarkable to see what they've come up with," Mello says.</p><p data-block-key="4e6do">Working in the Jim Hall Design and Prototyping Lab in the subbasement of the Eudora Hull Spalding Laboratory of Engineering, the students spent most of their afternoons, and many evenings, building and tweaking their airships. Among other tools, teams this year relied heavily on 3D printers to fabricate custom lightweight joints and carriages for the onboard electronics.</p><p data-block-key="7vqaj">"A lot of it has been prototypes, testing, failing, more prototypes, more testing, and failing, sort of going through a bunch of iterations of things," says Sofia Syed, one of the students on team B.O.O.M. "Last term, we worked on one style of electronics for the entire term until our final mock demo, and it didn't work as well as we'd hoped, so we had to revamp our design almost completely."</p><p data-block-key="9vfh3">Mello says such experiences are completely expected and are kind of the point of the class. Being able to work through problems and learn to communicate constructively with teammates, delegate tasks, follow schedules, and put in the time needed to "really grind on a problem" are some of the core values and abilities that ME 72 drives home, Mello says—and they are invaluable to engineers in the workforce.</p><p data-block-key="1e79l">Payal Patel from the Mechromancers team added that the students in the course also learned a lot from the experience of creating something from the ground up. "I'm not likely to be building a blimp in the future, but I think the process of building something from scratch is definitely something that I can carry over," Patel says. "We had to be very adaptable in this project because no one's really ever done this. Given the time limit that we had, we had to think quick on our feet."</p><p data-block-key="88t18">The day before the competition, students from team M.O.A.B. were making last-minute preparations, printing extra pieces, and ensuring the mesh carriage beneath the blimps, which is used to capture balls, was ready. Isabelle Ragheb was feeling pretty confident about her team's vehicles. "We've put in a lot of time and effort, but there are always last-minute things," she said.</p><p data-block-key="enjs6">Teammate Miles Jones agreed. "Sometimes, when you're flying, you just get unlucky. So just trying to control the controllables is the name of the game for us."</p><p data-block-key="47go2">M.O.A.B. worked hard to increase the maneuverability of its white airships and the accuracy with which they were piloted. At one point, the students changed the configuration of the electric ducted fans that steer the vehicles and push captured balls through goals. The team also added large cardboard fins to their blimps to improve stability. They even started 3D printing their airships' joints in a different orientation when they noticed that they were all cracking in one direction. "We have gone through so many iterations," Jones says.</p><p data-block-key="d9pmm">On the day of the competition, all the students' hard work paid off. The five teams competed in a round-robin style tournament with one team facing off against another in four-and-a-half-minute battles, trying to capture the most balls and score goals. If an airship captured and held onto a ball until the end of the match, it earned its team one point. If it managed to push a ball through any of the other team's goals in either direction, it garnered two points.</p><p data-block-key="2inip">Onlookers cheered when the blimps scored and sometimes groaned when an airship faltered. Students worked feverishly along the sidelines trying to make needed repairs and adjustments as the tournament progressed and some of the airships suffered damage.</p><p data-block-key="bo33e">Middle school students from Sierra Madre Middle School were on hand cheering for their favorite teams. "I bring them every year just to inspire them for the future," said Ravi Dev Anandhan, a science and robotics teacher at the middle school. "They see the end goal, and it motivates them. We enjoy it so much. Every year is different, and the students are completely wowed by it."</p><p data-block-key="21trn">After the initial round-robin tournament, in which each team faced off against everyother team once, one of the five teams was eliminated and the remaining four teams headed into the semifinals. Throughout the tournament, M.O.A.B. dominated each faceoff, racking up as many as 23 points in a single round. M.O.A.B. faced off against the Mechromancers in the final round. With under a minute left on the clock, one of the Mechromancers' pink blimps pushed two balls through a goal, narrowing the score to 8-6, and the crowd went wild. M.O.A.B clung to its lead by capturing and holding eight balls as time expired, and walked away with the ME 72 gear-shaped trophy.</p><p data-block-key="76t0b">Still, AJ Torres from the Mechromancers said after the competition that she had loved everything about the event. She had been excited about taking ME 72 since she first heard about the course. "It has really lived up to my expectations," Torres said. "I just feel sad that the class is over. It's going to be lonely without the shop."</p>Tanner Harms's Science Journey: Science, Sports, and Faith2024-03-11T21:24:00+00:002024-03-11T21:25:19.851252+00:00https://www.caltech.edu/about/news/science-journeys-stem-tanner-harms-fluid-mechanics<p data-block-key="en9k9">Everyone's journey into science is unique. Tanner Harms's path has centered around connecting with community, a love of facts and data, and a penchant for finding beauty in chaos.</p><p data-block-key="8sd2e"><b><i>The questions and answers below have been edited for clarity and length.</i></b></p><p data-block-key="214du"></p><p data-block-key="93j3g"><b>What motivated you to study fluid mechanics?</b></p><p data-block-key="d1ep">To be honest, studying experimental fluid mechanics was not my original plan. In fact, I can't say that I have ever had a specific long-term academic plan. I ended up in this field because my undergraduate advisor at the University of Wyoming, Professor Jonathan Naughton, believed in my potential and persuaded me to join his lab to study unsteady aerodynamics. At the time, I had applied to other programs in solid mechanics and mechatronics, but Jon's lab seemed like a good cultural fit, and it allowed me to keep my community in Laramie for a few more years. While I was doing research with him, I realized that I really enjoyed the research process—particularly in learning the data-science tools people use to understand fluids. I wanted to be someone who developed those tools and used them to help others solve a broad range of problems. That is what led me to Professor Beverley McKeon's lab at Caltech [McKeon is the Theodore van Karman Professor of Aeronautics].</p><p data-block-key="1mn5e"><b>What is something from your young life that connects to who you are now?</b></p><p data-block-key="2o0qv">A common thread throughout my life has been my faith in Jesus as a Christian. My parents raised me on Jesus's teachings in the Bible and, while my worldview has matured over time, my faith remains strong. In fact, it is the impetus behind many of my scientific pursuits. Given the fluids-based nature of my research, one passage I feel speaks to my studies is Psalm 19:1-2: "The heavens declare the glory of God and the sky above proclaims his handiwork. Day to day pours out speech, and night to night reveals knowledge."</p><p data-block-key="5m201"><b>What did you enjoy doing most when you were growing up?</b></p><p data-block-key="74ntg">I have always enjoyed all kinds of physical activity. I love playing sports, exercising, and going on adventures in the wilderness. However, my favorite sport growing up (and now) was wrestling. I wrestled from middle school all the way through college, and I still get to practice and coach the sport. To me, it feels like a physical variation of chess; you have to anticipate your opponent's response to your techniques and plan three steps ahead.</p><p data-block-key="12rgu"><b>How did childhood experiences shape the scientist you are today?</b></p><p data-block-key="5f33t">My parents put a high value on science and education when I was a child. Their insistence that I learn about the underlying mechanics of the world fostered in me the desire that I now have for understanding and scientific inquiry. Not only d id they value my scientific education at school, but they promoted it in our home. For instance, my sixth birthday party was NASA themed with paper-mache planets hung all around the house.</p><p data-block-key="6fc94"><b>Why are outreach activities, such as Science Journeys, important to you?</b></p><p data-block-key="cmsk8">Throughout my life (even to this day), I have not known with confidence what my next steps should be. I have relied on the advice and inspiration of many mentors who have generously given me their time, affection, and confidence. Without their help—without their friendship—I would be nowhere near where I am today. I hope that I can give back to people the way that my mentors have given to me; that I can inspire new generations of talented young people to pursue their dreams in STEM or otherwise.</p><p data-block-key="no6v"><b>What advice would you share with your middle school self?</b></p><p data-block-key="edekv">I am so thankful for the trajectory that I have been given that I am not confident any specific advice I might give my younger self would lead to a better outcome. However, here are some reflections that I think my younger self would have done well to ponder:</p><ol><li data-block-key="c9jlb">It is good to be strong, better to be educated, and best to be kind.</li><li data-block-key="cll1v">Humility, gratitude, and generosity are the marks of a truly great leader.</li><li data-block-key="dloj8">Community is an antidote to chaos, but one's company may yet lead them to destruction.</li><li data-block-key="bolk6">Eat not the bread of anxious toil. Rest is a gift.</li><li data-block-key="44g0g">Relationships are life's most valuable currency.</li><li data-block-key="efvim">Sometimes you win; sometimes you lose. Play excellently because you love the game.</li><li data-block-key="fh85t">Experience gains interest. Challenge yourself and don't cut corners.</li><li data-block-key="eijk8">Always strive to do the right thing, even when it hurts.</li></ol><p data-block-key="bhgi6"><i>On February 23, 2024, Harms presented his Science Journey to a group of approximately 250 students, teachers, parents, and Caltech and Pasadena community members. Watch the full presentation, including the student Q&A, below.</i></p><h2 data-block-key="hr8sk"><b>About the Series</b></h2><p data-block-key="4s82b">In Science Journeys, Caltech graduate students and postdoctoral scholars discuss a range of scientific topics that will spark students' curiosity and provide educators with supplemental resources to continue that exploration in the classroom.</p><p data-block-key="9k6gf">Each one-hour field trip includes a presentation and Q&A. Programs are designed especially for middle and high school students, but everyone is welcome to attend. All events are free through the generosity of the <a href="https://events.caltech.edu/support/fob?utm_medium=web&utm_campaign=science-journeys&utm_source=caltechnews&utm_content=&utm_term=">Friends of Beckman Auditorium</a>, but registration is required.</p><p data-block-key="3p0fq">Visit the <a href="https://events.caltech.edu/series/science-journeys#upcoming-science-journeys?utm_medium=web&utm_campaign=science-journeys&utm_source=caltechnews&utm_content=&utm_term=">Science Journeys website</a> to register yourself or your classroom for the April and May 2024 events and to watch past presentations.</p><p data-block-key="hr8sk"><i>Questions? Contact Mary Herrera at mhh@caltech.edu.</i></p>Using AI to Predict the Spread of Lung Cancer2024-03-06T18:40:00+00:002024-03-07T17:46:51.265536+00:00Kimm Fesenmaierkfesenma@caltech.eduhttps://www.caltech.edu/about/news/using-ai-to-predict-the-spread-of-lung-cancer<p data-block-key="taf1i">For decades, scientists and pathologists have tried, without much success, to come up with a way to determine which individual lung cancer patients are at greatest risk of having their illness spread, or metastasize, to other parts of the body. Now a team of scientists from Caltech and Washington University School of Medicine in St. Louis has fed that problem to artificial intelligence (AI) algorithms, asking computers to predict which cancer cases are likely to metastasize. In a novel pilot study of non-small cell lung cancer (NSCLC) patients, AI outperformed expert pathologists in making such predictions.</p><p data-block-key="bo3dq">These predictions about the progression of lung cancer have important implications in terms of an individual patient's life. Physicians treating early-stage NSCLC patients face the extremely difficult decision of whether to intervene with expensive, toxic treatments, such as chemotherapy or radiation, after a patient undergoes lung surgery. In some ways, this is the more cautious path because more than half of stage I–III NSCLC patients eventually experience metastasis to the brain. But that means many others do not. For those patients, such difficult treatments are wholly unnecessary.</p><p data-block-key="d8l6v">In the new study, <a href="https://pathsocjournals.onlinelibrary.wiley.com/doi/full/10.1002/path.6263">published this week</a> in the <i>Journal of Pathology</i>, the collaborators show that AI holds promise as a tool that could one day aid physicians in this decision-making.</p><p data-block-key="3hbd6">"Overtreatment of cancer patients is a big problem," says Changhuei Yang, the Thomas G. Myers Professor of Electrical Engineering, Bioengineering, and Medical Engineering at Caltech and an investigator with the Heritage Medical Research Institute. "Our pilot study indicates that AI may be very good at telling us in particular which patients are very unlikely to develop brain cancer metastasis."</p><p data-block-key="foua6">Yang cautions that the work is only a first step and that a larger study is needed to validate the findings.</p><p data-block-key="357l1">The team worked with data and biopsy images collected from 118 NSCLC patients at Washington University School of Medicine in St. Louis. Typically, a pathologist reviews such images, scouring them for abnormalities within the cells that might suggest the cancer is progressing.</p><p data-block-key="8792i">Caltech electrical engineers led by Yang used hundreds of thousands of image tiles pulled from those 118 original biopsy images to train a type of AI program called a deep-learning network. They also provided follow-up data about which patients went on to develop brain metastases within five years of diagnosis and which did not.</p><p data-block-key="5d6gj">"We essentially asked the network to <i>learn</i> from all these images, to pick out some features from the contextual information that could indicate something about a patient's outcome," says graduate student Haowen Zhou, first author of the new paper. Then the network was given 40 additional biopsy images and asked to determine whether the patients had gone on to experience brain metastases.</p><p data-block-key="7v6jv">The AI network was able to correctly predict whether an individual NSCLC patient had experienced brain metastasis 87 percent of the time. In contrast, four expert pathologists who reviewed the same biopsy images were able to make the correct predictions only 57 percent of the time.</p><p data-block-key="etr65">"Our study is an indication that AI methods may be able to make meaningful predictions that are specific and sensitive enough to impact patient management," says Richard Cote, head of the Department of Pathology & Immunology at Washington University School of Medicine and co-principal investigator of the new study. He notes that for the earliest-stage NSCLC patients (those classified as stage I), the AI results were even better than those for the whole study and that these predictions were based solely on basic, routinely processed microscopic slides. By giving the AI information on additional factors such as the severity of the disease and any additional biomarkers, the researchers expect that they will be able to improve the predictive powers of the AI program going forward.</p><p data-block-key="1ge6h">Interestingly, the AI program does not indicate exactly what factors cause it to make certain predictions. So, the team is also working to uncover the subtle and complex features of tumor cells and their surroundings that the AI program might be homing in on.</p><p data-block-key="2v9qn">"It's looking at what we would look at as a pathologist," Cote says. "But it's seeing more than we can see." Perhaps, he says, once scientists learn exactly what AI is focusing on, they will be able to develop new therapeutics to address those indicators.</p><p data-block-key="9m6fl">Also looking forward, Yang's group at Caltech is interested in developing instrumentation and processes that would help scientists and clinicians collect more uniform and higher-quality biopsy images to boost the accuracy of AI predictions. "Once we can see what the AI is doing, we can start to think about how to design imaging and microscopy instruments to more optimally get the data that the AI wants," Yang says. "We can move away from imaging instruments designed for human use and move toward making instruments that are optimized for machine use."</p><p data-block-key="dqsbi">Other Caltech co-authors on the paper, "AI-guided histopathology predicts brain metastasis in lung cancer patients," are graduate student Steven (Siyu) Lin and postdoctoral scholar research associate Simon Mahler. Additional co-authors from Washington University School of Medicine include Mark Watson, Cory Bernadt, Chieh-yu Lin, Jon Ritter, Alexander Wein, Sid Rawal, and Ramaswamy Govindan. The work was supported by the Heritage Medical Research Institute, Caltech's Center for Sensing to Intelligence, the Washington University in St. Louis School of Medicine Personalized Medicine Initiative, and the National Cancer Institute.</p>Tying Knots Inside Lasers2024-03-01T14:16:00+00:002024-03-01T16:36:15.151686+00:00Cynthia Ellerceller@caltech.eduhttps://www.caltech.edu/about/news/tying-knots-inside-lasers<p data-block-key="7idkv"></p><p data-block-key="5ers7">What do you picture in your mind's eye when you hear the word "laser"? A light saber? A cat toy? The sensor at the supermarket reading barcodes as fast as the eye can blink?</p><p data-block-key="3q9if">These are all lasers, but there are so many more in so many sizes and colors with capabilities that have yet to be tapped or even imagined. Assistant Professor of Electrical Engineering and Applied Physics Alireza Marandi is in the business of dreaming up these lasers and creating them in the lab.</p><p data-block-key="4ueag">Marandi's latest investigation involves mode-locked lasers, which emit light in steady pulses rather than in a single continuous beam. These pulses can be extremely short, counted in picoseconds (trillionths of a second) or femtoseconds (quadrillionths of a second), and can carry ultrahigh powers in such short times. Pulses from mode-locked lasers have been used in many applications, for instance, for eye surgery, by providing narrowly targeted cutting power without creating the undue heat that a continuous laser beam would cause.</p><p data-block-key="d5qm9">Mode-locking involves locking the amplitudes and phases of the light waves that traverse a laser's resonant cavity. When mode-locking is achieved, these resonant waves act in concert with one another and typically form a steadily pulsing pattern. Marandi's team is adding topological robustness to a mode-locked laser by introducing specific couplings among the resonant light pulses in the laser cavity.</p><p data-block-key="3badp">The resulting topological temporal mode-locking creates laser pulse patterns that can tolerate imperfections and disorders arising from manufacturing or environmental noise sources.</p><p data-block-key="dj9qq">"This fundamental research could potentially have many applications," Marandi says. "By realizing topological behaviors in mode-locked lasers, we are essentially creating a knot that can make the laser's behavior more robust against noise. If the laser is ordinarily mode-locked and you shake it, everything goes crazy. But if the laser pulses are knotted together, you can shake the system, and nothing chaotic will happen, at least for a certain range of shakings."</p><p data-block-key="easme">Topologically protected mode-locked lasers can enable the creation of better frequency combs, which are used in communication, sensing, and computing applications. "The output of a mode-locked laser in the frequency domain is a frequency comb, that is, many equidistant narrow spectral peaks," Marandi explains. "Frequency combs are typically prone to noise sources and environmental instabilities. By utilizing the topological behaviors in a mode-locked laser, the resulting frequency comb can be protected against some of these noise sources."</p><p data-block-key="33tgu">In the future, Marandi hopes to utilize the rich physics of this new type of laser to access regimes of nonlinear topological physics that are not accessible with other experimental platforms as well as developing advanced types of sensors and computing hardware.</p><p data-block-key="1ehuq">The <a href="https://doi.org/10.1038/s41567-024-02420-4">paper</a> is published in <i>Nature Physics</i> and is titled "Topological Temporally Mode-Locked Laser." Co-authors are Christian R. Leefmans, Midya Parto, James Williams, and Gordon H.Y. Li, all of Caltech; Avik Dutt of Stanford University and the University of Maryland; and Franco Nori of the University of Michigan and the RIKEN Center for Quantum Computing in Japan. Funding sources include the National Science Foundation, the Air Force Office of Scientific Research, the Army Research Office, the Japan Society for the Promotion of Science, the Asian Office of Aerospace Research and Development, the Foundational Questions Institute, and NTT Research.</p><p data-block-key="f2plb"></p>Building Bionic Jellyfish for Ocean Exploration2024-02-28T21:14:00+00:002024-02-29T20:39:29.993837+00:00Emily Velascoevelasco@caltech.eduhttps://www.caltech.edu/about/news/building-bionic-jellyfish-for-ocean-exploration<p data-block-key="fw56j">Jellyfish can't do much besides swim, sting, eat, and breed. They don't even have brains. Yet, these simple creatures can easily journey to the depths of the oceans in a way that humans, despite all our sophistication, cannot.</p><p data-block-key="87h66">But what if humans could have jellyfish explore the oceans on our behalf, reporting back what they find? New research conducted at Caltech aims to make that a reality through the creation of what researchers call biohybrid robotic jellyfish. These creatures, which can be thought of as ocean-going cyborgs, augment jellyfish with electronics that enhance their swimming and a prosthetic "hat" that can carry a small payload while also making the jellyfish swim in a more streamlined manner.</p><p data-block-key="bik2k">The work, published in the journal <i>Bioinspiration & Biomimetics,</i> was conducted in the lab of John Dabiri (MS '03, PhD '05), the Centennial Professor of Aeronautics and Mechanical Engineering, and builds on his previous work augmenting jellyfish. Dabiri's goal with this research is to use jellyfish as robotic data-gatherers, sending them into the oceans to collect information about temperature, salinity, and oxygen levels, all of which are affected by Earth's changing climate.</p><p data-block-key="dkub8">"It's well known that the ocean is critical for determining our present and future climate on land, and yet, we still know surprisingly little about the ocean, especially away from the surface," Dabiri says. "Our goal is to finally move that needle by taking an unconventional approach inspired by one of the few animals that already successfully explores the entire ocean."</p><p data-block-key="5q88g"></p><embed embedtype="media" url="https://www.youtube.com/watch?v=_ZfthP_7s5g"/><p data-block-key="e6d6c"></p><p data-block-key="ac1hs">Media assets: <a href="https://mediaassets.caltech.edu/robotic-jellyfish-explorers">Robotic Jellyfish Explorers</a></p><p data-block-key="9kaih">Throughout his career, Dabiri has looked to the natural world, jellyfish included, for inspiration in solving engineering challenges. This work began with early attempts by Dabiri's lab to develop a mechanical robot that swam like jellyfish, which have the most efficient method for traveling through water of any living creature. Though his research team succeeded in creating such a robot, that robot was never able to swim as efficiently as a real jellyfish. At that point, Dabiri asked himself, why not just work with jellyfish themselves?</p><p data-block-key="ah3u4">"Jellyfish are the original ocean explorers, reaching its deepest corners and thriving just as well in tropical or polar waters," Dabiri says. "Since they don't have a brain or the ability to sense pain, we've been able to collaborate with bioethicists to develop this biohybrid robotic application in a way that's ethically principled."</p><p data-block-key="567lo">Previously, Dabiri's lab implanted jellyfish with a kind of electronic pacemaker that controls the speed at which they swim. In doing so, they found that if they made jellyfish swim faster than the leisurely pace they normally keep, the animals became even more efficient. A jellyfish swimming three times faster than it normally would uses only twice as much energy.</p><p data-block-key="7o4mj">This time, the research team went a step further, adding what they call a forebody to the jellies. These forebodies are like hats that sit atop the jellyfish's bell (the mushroom-shaped part of the animal). The devices were designed by graduate student and lead author Simon Anuszczyk (MS '22), who aimed to make the jellyfish more streamlined while also providing a place where sensors and other electronics can be carried.</p><p data-block-key="a4hbg"></p><embed alt="A photo of Simon Anuszczyk and John Dabiri. They both smile and stand in front of a large tank of water." embedtype="image" format="RightAlignMedium" id="10389"/><p data-block-key="e8mv7"></p><p data-block-key="erg9t">"Much like the pointed end of an arrow, we designed 3D-printed forebodies to streamline the bell of the jellyfish robot, reduce drag, and increase swimming performance," Anuszczyk says. "At the same time, we experimented with 3D printing until we were able to carefully balance the buoyancy and keep the jellyfish swimming vertically."</p><p data-block-key="9ht46">To test the augmented jellies' swimming abilities, Dabiri's lab undertook the construction of a massive vertical aquarium inside Caltech's Guggenheim Laboratory. Dabiri explains that the three-story tank is tall, rather than wide, because researchers want to gather data on oceanic conditions far below the surface.</p><p data-block-key="2k65c">"In the ocean, the round trip from the surface down to several thousand meters will take a few days for the jellyfish, so we wanted to develop a facility to study that process in the lab," Dabiri says. "Our vertical tank lets the animals swim against a flowing vertical current, like a treadmill for swimmers. We expect the unique scale of the facility—probably the first vertical water treadmill of its kind—to be useful for a variety of other basic and applied research questions."</p><p data-block-key="bm3q4"></p><embed alt="A biohybrid jellyfish traverses the three-story tank in which swimming tests were conducted. The photo is a composit image, showing the jellyfish in multiple positions on its descent to the bottom." embedtype="image" format="LeftAlignSmall" id="10390"/><p data-block-key="6sngh"></p><p data-block-key="ca0a2">Swim tests conducted in the tank show that a jellyfish equipped with a combination of the swimming pacemaker and forebody can swim up to 4.5 times faster than an all-natural jelly while carrying a payload. The total cost is about $20 per jellyfish, Dabiri says, which makes biohybrid jellies an attractive alternative to renting a research vessel that can cost more than $50,000 a day to run.</p><p data-block-key="793n4">"By using the jellyfish's natural capacity to withstand extreme pressures in the deep ocean and their ability to power themselves by feeding, our engineering challenge is a lot more manageable," Dabiri adds. "We still need to design the sensor package to withstand the same crushing pressures, but that device is smaller than a softball, making it much easier to design than a full submarine vehicle operating at those depths.</p><p data-block-key="43iq3">"I'm really excited to see what we can learn by simply observing these parts of the ocean for the very first time," he adds.</p><p data-block-key="ff45j">Dabiri says future work may focus on further enhancing the bionic jellies' abilities. Right now, they can only be made to swim faster in a straight line, such as the vertical paths being designed for deep ocean measurement. But further research may also make them steerable, so they can be directed horizontally as well as vertically.</p><p data-block-key="2sqcr">The paper describing the work, "<a href="https://iopscience.iop.org/article/10.1088/1748-3190/ad277f">Electromechanical enhancement of live jellyfish for ocean exploration</a>," appears in the February 28 issue of <i>Bioinspiration & Biomimetics.</i> Co-authors are Anuszczyk and Dabiri.</p><p data-block-key="4nf9s">Funding for the research was provided by the National Science Foundation and the Charles Lee Powell Foundation.</p>Caltech Professors Win 2024 Sloan Fellowships2024-02-20T17:21:35.741172+00:002024-02-20T17:21:35.531604+00:00Whitney Clavinwclavin@caltech.eduhttps://www.caltech.edu/about/news/caltech-professors-win-2024-sloan-fellowships<p data-block-key="sjv42">Four Caltech faculty members have been awarded the prestigious Sloan Research Fellowship for 2024: Katie Bouman, assistant professor of computing and mathematical sciences, electrical engineering and astronomy; Lee McCuller, assistant professor of physics; Vikram Ravi, assistant professor of astronomy; and Antoine Song, assistant professor of mathematics.</p><p data-block-key="99nha">The fellowships honor exceptional U.S. and Canadian researchers "whose creativity, innovation, and research accomplishments make them stand out as the next generation of leaders," according to the <a href="https://sloan.org/">Alfred P. Sloan Foundation</a>, which has been granting the awards annually since 1955. The Caltech professors are among 126 early-career scientists who have been selected to receive the fellowships, which come with $75,000 over two years to advance research projects.</p><p data-block-key="4l2id"><a href="/about/news/seeing-farther-and-deeper-interview-katie-bouman">Katie Bouman</a> is a computational imaging scientist whose methods combine ideas from signal processing, computer vision, machine learning, and physics to bring out hidden signals in scientific and technical data. She is a key member of the <a href="https://eventhorizontelescope.org/">Event Horizon Telescope</a> project, which made history in 2019 by unveiling the first image of a black hole, in this case, a supermassive black hole lying at the heart of the M87 galaxy. Using data acquired by a global network of radio telescopes, Bouman and her teammates developed a computational approach that transformed the black hole data into an image. Since then, her team has helped produce an <a href="/about/news/caltech-researchers-help-generate-first-image-of-black-hole-at-the-center-of-our-galaxy">image of the supermassive black hole at the heart of our Milky Way Galaxy</a>, called Sagittarius A*, as well as a new <a href="/about/news/new-data-same-great-appearance-for-m87">image of the M87 black hole made with enhanced data</a>. Bouman is also developing next-generation computational cameras for other imaging problems in astronomy, medicine, and seismology, where traditional cameras will not work.</p><p data-block-key="899b3"><a href="/about/news/at-the-edge-of-physics">Lee McCuller</a> is an expert at creating technologies that make the most precise measurements in the world. These quantum measurements are at the heart of the <a href="https://www.ligo.caltech.edu/">Laser Interferometer Gravitational-wave Observatory</a>(LIGO), which has been detecting gravitational waves from colliding black holes and neutron stars since it first detected ripples in space-time in 2015. McCuller helped lead the development of essential technology at LIGO based on a concept called quantum squeezing. This method helps reduce unwanted noise in LIGO's detectors—noise that bubbles up from the quantum realm—to make the facilities even more sensitive to gravitational waves. Recently, Lee and his LIGO collaborators <a href="/about/news/ligo-surpasses-the-quantum-limit">took the technology one step further</a> to make quantum squeezing work across the range of gravitational frequencies detected by LIGO. The research helped surpass limits imposed by quantum physics and made LIGO even more powerful.</p><p data-block-key="1kqt6"><a href="/about/news/build-it-and-they-will-come-fast-radio-bursts">Vikram Ravi</a> is an astronomer specializing in energetic dynamic events, such as fast radio bursts, or FRBs, which are powerful eruptions of radio waves that <a href="/about/news/fast-radio-burst-pinpointed-distant-galaxy">originate primarily from remote galaxies</a> and whose cause remains unknown. Ravi co-led the development of the Deep Synoptic Array-110, an array of radio dishes at Caltech's Owens Valley Radio Observatory, which has now identified and pinpointed over 60 FRBs to their galaxies of origin. Ravi plans to use this growing sample—a significant fraction of the fewer than 90 FRBs so far associated with galaxies—to better understand <a href="/about/news/cosmic-burst-probes-milky-ways-halo">how matter is distributed within and in between galaxies</a>. He is also embarking on a new program to identify tidal disruption events, or TDEs, which occur when a star wanders too close to a black hole and is devoured. Ravi and his colleagues will use data from the <a href="https://ztf.ipac.caltech.edu/">Zwicky Transient Facility</a> (ZTF) at Caltech's Palomar Observatory to search for more obscure TDEs, and help piece together the puzzles of how often these events occur as well as why they do not look the same when viewed at different wavelengths of light.</p><p data-block-key="5fteo"><a href="/about/news/Geometry_of_Minimal_Surfaces">Antoine Song</a> specializes in differential geometry, the study of shapes using analysis and differential equations. His goal is to better understand minimal surfaces, geometrical shapes that minimize total surface area and total energy; for instance, a circular wire frame dipped in soapy water leads to a film with a minimal optimal shape. For his PhD thesis, Song showed that there are infinitely many minimal surfaces in any three-dimensional space. Recently, Song and his colleague Conghan Dong, a graduate student at Stony Brook University, helped prove an aspect of Albert Einstein's general theory of relativity, showing that "a sequence of curved spaces with smaller and smaller amounts of mass will eventually converge to a flat space with zero curvature," according to <a href="https://www.quantamagazine.org/a-century-later-new-math-smooths-out-general-relativity-20231130/">Quanta Magazine</a>.</p><p data-block-key="12ql6">Read more about the Sloan Research Fellowships at its <a href="https://sloan.org/fellowships/">website</a>.</p>Adam Wierman is Named a Distinguished Member of ACM2024-02-01T18:49:55.715129+00:002024-02-01T18:49:55.591360+00:00Cynthia Ellerceller@caltech.eduhttps://www.caltech.edu/about/news/wierman-named-distinguished-membeer-of-ACM<p data-block-key="7idkv"></p><p data-block-key="705d3">Adam Wierman, professor of computing and mathematical sciences and director of information science and technology, has been named a Distinguished Member of the <a href="https://www.acm.org/">Association for Computing Machinery</a> (ACM).</p><p data-block-key="difo6">"Many of these new 52 Distinguished Members have been selected for important technical achievements," Yannis Ioannidis, president of ACM, said. "Others have been chosen because of their service and/or work in computer science education, which lays the foundation for the future of the field."</p><p data-block-key="9l64s">To qualify as a Distinguished Member, candidates must have spent at least 15 years in the profession and made significant contributions to the field of computing, while also serving as a mentor for others.</p><p data-block-key="d8f2b">Wierman takes a theory-first system design approach, but his theoretical work in mathematical tools for machine learning has been quickly deployed into algorithms that optimize everything from adaptive EV charging (PowerFlex), smart grid management (SCE), and resource allocation in the cloud (Microsoft, Google), to the design of carbon-first data centers (HP, Apple). "One goal of the work in our group," Wierman says, "is to design the algorithms needed for 100 percent renewable-driven, carbon-free data centers."</p><p data-block-key="a0u3f">As a professor at Caltech for the past 15 years, Wierman has mentored hundreds of undergraduates, graduate students, and postdocs in the science and art of making networked systems sustainable and resilient. He also teaches students about the present and future of computer science education from kindergarten through community college.</p><p data-block-key="47v5">"Working with students and collaborators across computer science and beyond has been extremely rewarding," Wierman says. "It is an honor to have my work recognized by the ACM."</p><p data-block-key="c9nnc">This year's ACM honorees are both academics and industry professionals. They come not only from the United States and Canada, but also from Italy, Denmark, Finland, Hong Kong, Israel, China, Scotland, Germany, and Belgium.</p>New Data, Same Great Appearance for M87*2024-01-22T20:11:00+00:002024-01-22T22:02:52.705391+00:00Emily Velascoevelasco@caltech.eduhttps://www.caltech.edu/about/news/new-data-same-great-appearance-for-m87<p data-block-key="6rn4g">Nearly five years ago, a globe-spanning team of astronomers gave the world its first-ever glimpse of a black hole. Now the team has validated both their original findings and our understanding of black holes with <a href="https://eventhorizontelescope.org/M87-one-year-later-proof-of-a-persistent-black-hole-shadow">a new image of the supermassive black hole M87*</a>. This supermassive black hole, 6.5 billion times the mass of our Sun, resides at the center of the Messier 87 (M87) galaxy in the Virgo galaxy cluster, located 55 million light-years from Earth.</p><p data-block-key="9nclk">The new image, like the old one, was captured by the Event Horizon Telescope (EHT), an array of radio telescopes stretching across the planet. These new data, however, were gathered a year later, in 2018, and benefitted from enhancements in the telescope array, notably with the inclusion of a telescope in Greenland.</p><p data-block-key="2fdu3">EHT's original image of M87* was important not just because it represented the first time humans had imaged a black hole, but also because the object looked the way it was <i>supposed</i> to look. Notably, the image showed what is known as a black-hole shadow—a dark region at the center of a glowing disk of hot matter circling the black hole. A black-hole shadow isn't a shadow in the same sense as the one you cast when you walk outside on a sunny day. Instead, the dark region is created by the black hole's immense gravitational field, which is so strong that light cannot escape it. Since no light leaves a black hole, it appears dark.</p><p data-block-key="bf8nl">Additionally, that strong gravity bends light that passes near the black hole without falling into it, effectively acting like a lens. This is known as gravitational lensing, and it creates a ring of light that can be seen no matter which angle the black hole is viewed from. These effects were both predicted from Albert Einstein's theory of general relativity. Because M87*'s image shows these effects, it is strong evidence that general relativity and our understanding of the physics of black holes is correct.</p><p data-block-key="8hg9m">This new M87* image was produced with key contributions from an imaging team at Caltech, including Professor <a href="https://www.cms.caltech.edu/people/klbouman">Katherine (Katie) L. Bouman</a>, assistant professor of computing and mathematical sciences, electrical engineering, and astronomy; former Caltech PhD student Nitika Yadlapalli Yurk (PhD '23); and current Caltech postdoctoral research associate in computing and mathematical sciences Aviad Levis.</p><p data-block-key="f4r33"></p><embed alt="Bouman" embedtype="image" format="RightAlignSmall" id="6734"/><p data-block-key="bblou"></p><p data-block-key="fii8q">Bouman is a coordinator of the EHT Imaging Working Group and was a postdoctoral fellow at the Harvard Smithsonian Center for Astrophysics and co-lead of the EHT imaging team when the original image was published in 2019. In that role, she helped develop the algorithms that assembled the trove of data collected by the EHT's multiple radio telescopes into a single, cohesive image. Since joining the Caltech faculty, Bouman, who is also a Rosenberg Scholar and Heritage Medical Research Institute Investigator, has continued her work with EHT. She also co-led the <a href="/about/news/caltech-researchers-help-generate-first-image-of-black-hole-at-the-center-of-our-galaxy">imaging of the Milky Way's supermassive black hole</a> published in 2022.<br/></p><embed alt="A portrait of Nitika Yadlapalli Yurk. She stands before an outdoor wall, wearing a blazer and smiling." embedtype="image" format="LeftAlignSmall" id="10330"/><p data-block-key="fatpq"></p><p data-block-key="5m84g">Yurk joined the EHT Collaboration in 2020 and played an active role in the imaging team for the latest M87* image. Her main contributions included developing synthetic datasets to be used in the training and validation of the imaging algorithms. Yurk also wrote software that was used in the exploration of image candidates. She was recently recognized by the EHT for her efforts with a PhD Thesis Award for the advances she brought to the imaging and validation of the most recent M87* image. She is currently a NASA Postdoctoral Program fellow at JPL, which Caltech manages for NASA.</p><p data-block-key="e2to6">Imaging an object like M87* with the EHT is very different than imaging a planet like Saturn with a conventional telescope. Instead of seeing light, the EHT observes the radio waves emitted by objects and must computationally combine the information to form a picture.</p><p data-block-key="4b63m">"The raw data that comes out of these telescopes are basically just voltage values," Yurk says. "I like to describe radio telescopes as the world's most sensitive volt meters, and they collect voltages really accurately from different parts of the sky."</p><p data-block-key="7d8q4">Turning those voltage values into an image is tricky, Bouman says, because the information the researchers are working with is incomplete, and there is nothing to compare the image against since no one has seen M87* with their own eyes.</p><p data-block-key="6a2h">"We don't want to plug in our expectations of what the black hole should look like when we're computationally forming the image," Bouman says. "Otherwise, it might lead us to an image that we expect rather than one that captures reality."</p><p data-block-key="6dv39">To avoid that problem, the researchers test their image processing algorithms with what is known as synthetic data, a suite of simulated images with simple geometric shapes. Those data are run through the algorithms to produce an image. If the output image is true to the input image, they know the algorithm is working correctly and would be able to accurately see surprising structures around the black hole.</p><p data-block-key="5momq">Bouman says that process, which was co-led by Yurk, involved exploring hundreds of thousands of parameters to gauge the effectiveness of the algorithms in reconstructing different image structures. The team found that with the addition of the Greenland telescope to the EHT, the methods more robustly recovered features in the images.</p><p data-block-key="10pd0">The process produced an image of M87* that is only slightly different than the first. The most obvious difference is that the brightest portion of the glowing ring surrounding M87* has shifted about 30 degrees counterclockwise. According to the EHT, that movement is likely the result of the turbulent flow of matter around a black hole. Importantly, the ring has remained the same size, which was also predicted by general relativity.</p><p data-block-key="3v6vm">Bouman adds that the team's ability to produce another image of M87* with new data that agrees so closely with the previous image is exciting.</p><p data-block-key="2a90q">"I think that people are going to ask, 'Why is this important? You already showed a picture of M87*.' Other groups have reproduced the M87* picture with data that were taken in 2017. But it's a totally different thing to have a new dataset taken a different year and to come to the same conclusions. Reproducibility with independent data is a big deal, too."</p>Measuring Stress2024-01-22T04:24:06.847003+00:002024-01-22T04:24:06.737050+00:00Cynthia Ellerceller@caltech.eduhttps://www.caltech.edu/about/news/measuring-stress<p data-block-key="7idkv"></p><p data-block-key="c7lsh">In the latest of a series of innovative designs for wearable sensors that use sweat to identify and measure physiological conditions, Caltech's Wei Gao, assistant professor of medical engineering, has devised an "electronic skin" that continuously monitors nine different markers that characterize a stress response. Those wearing this electronic skin—a small, thin adhesive worn on the wrist, called CARES (consolidated artificial-intelligence-reinforced electronic skin)—are free to engage in all their normal daily activities with minimal interference during testing, which allows for the measurement of both baseline and acute levels of stress.</p><p data-block-key="csh3t">Stress is a slippery concept. We talk about "feeling stressed" or a situation "being stressful," and we may attach stress to physical symptoms: "I have a stress headache" or "I'm grinding my teeth at night. It must be stress." The term stress can apply to all sorts of feelings, symptoms, behaviors, and experiences.</p><p data-block-key="947af">Hans Selye, a physician and chemist born in Vienna in 1907, was the first to define stress as a medical condition. Struck by the similar complaints—such as tiredness, low appetite, and lack of motivation—that he heard from patients suffering from very different illnesses, Selye speculated that all of the patients were responding to what they had in common: being sick. He defined stress as a "nonspecific response of the body to any demand."</p><p data-block-key="d7taf">Stress may be experienced positively as excitement or energy, or negatively as shock or anxiety. But however stress may be experienced emotionally, it is now widely agreed that depending on its severity and duration, both acute and chronic stress can damage our physical and mental health, and reduce our ability to function as we would like.</p><p data-block-key="apmm7">Because stress is, as Selye described it, "nonspecific," there is no single biomarker available to tell us definitively whether or how much a person is stressed. However, stress generates a constellation of bodily reactions that, taken together, can provide a measure of stress independent of self-reports. Gao is monitoring this constellation with CARES.</p><p data-block-key="c5oa5">"When a person is under stress, hormones like epinephrine, norepinephrine, and cortisol are released into the bloodstream," explains Gao, who is also an investigator with the Heritage Medical Research Institute and a Ronald and JoAnne Willens Scholar. "Sweat becomes rich with metabolites like glucose, lactate, and uric acid, and electrolytes like sodium, potassium, and ammonium. These are substances we have measured before using <a href="/about/news/new-wearable-sensor-detects-even-more-compounds-in-human-sweat">microfluidic sampling on a wearable sweat sensor</a>. What is new in CARES is that sweat sensors are integrated with sensors that record pulse waveforms, skin temperature, and galvanic skin response: physiological signals that also indicate stress in predictable ways."</p><p data-block-key="f1m7b">New materials further boost the performance of CARES. Though previously used materials for sweat sensors could be produced efficiently via inkjet printing and were capable of accurate measurement of even very scarce compounds, the materials gradually broke down in the presence of bodily fluids. The introduction of a nickel-based compound helps to stabilize the enzymatic-based sensors, such as those that detect lactate or glucose, as does a new polymer added to the ion-based sensors, which detect biomarkers like sodium or potassium. "Adding these new materials greatly enhances the sensor stability during long-term operation," Gao reports. Like previous sweat sensors, CARES can be battery powered and can wirelessly communicate with a phone or computer via Bluetooth.</p><p data-block-key="brr2v">Another important innovation with CARES is the addition of machine learning. Because stress comes in many different forms and stimulates a complex response affecting many different bodily systems, interpreting a wealth of data accurately is key to the usefulness of CARES and other sensors. Experiments inducing stress in subjects wearing the CARES device demonstrated that the sensor accurately measures the interrelatedness of physiological (such as pulse) and chemical (such as glucose) biomarkers. Subjects also answered questionnaires to self-report their feelings of anxiety and psychological stress before and after exposure to stressful situations like vigorous exercise or intense video gameplay. Data showed clear correlations between self-reports of stress and its physicochemical correlates as measured by CARES.</p><p data-block-key="7h9oa">"High levels of stress and anxiety caused by demanding work environments, such as those experienced by soldiers or astronauts, can significantly affect performance," Gao notes. "Early detection of the severity of stress allows for timely intervention. Our wearable sensor, combined with machine learning, has the potential to provide real-time stress-level insights."</p><p data-block-key="2230l">The paper describing the CARES device, titled "A physicochemical sensing electronic skin for stress response monitoring," appears in the January 19 issue of <i>Nature Electronics.</i> Co-authors are Changhao Xu (MS '20), Yu Song, Juliane R. Sempionatto, Samuel R. Solomon (MS '23), You Yu, Roland Yingjie Tay, Jiahong Li, Wenzheng Heng (MS '23), Jihong Min (MS '19), and Alison Lao of Caltech; Hnin Y. Y. Nyein of Hong Kong University of Science and Technology; and Tzung K. Hsiai and Jennifer A. Sumner of UCLA.</p><p data-block-key="j1sk">Funding for the research was provided by the Translational Research Institute for Space Health through NASA, the Office of Naval Research, the Army Research Office, the National Institutes of Health, the National Science Foundation, the National Academy of Medicine, and the Heritage Medical Research Institute.</p>Space Solar Power Project Ends First In-Space Mission with Successes and Lessons2024-01-16T17:04:01.255683+00:002024-01-16T17:04:01.153492+00:00https://www.caltech.edu/about/news/space-solar-power-project-ends-first-in-space-mission-with-successes-and-lessons<p data-block-key="sxeet">One year ago, Caltech's Space Solar Power Demonstrator (SSPD-1) launched into space to demonstrate and test three technological innovations that are among those necessary to make space solar power a reality.</p><p data-block-key="65j95">The spaceborne testbed demonstrated the ability to <a href="/about/news/in-a-first-caltechs-space-solar-power-demonstrator-wirelessly-transmits-power-in-space">beam power wirelessly in space</a>; it measured the efficiency, durability, and function of a variety of different types of solar cells in space; and gave a real-world trial of the design of a lightweight deployable structure to deliver and hold the aforementioned solar cells and power transmitters.</p><p data-block-key="9jnqp">Now, with SSPD-1's mission in space concluded, engineers on Earth are celebrating the testbed's successes and learning important lessons that will help chart the future of space solar power.</p><p data-block-key="87im6">"Solar power beamed from space at commercial rates, lighting the globe, is still a future prospect. But this critical mission demonstrated that it should be an achievable future," says Caltech President Thomas F. Rosenbaum, the Sonja and William Davidow Presidential Chair and professor of physics.</p><p data-block-key="3ioun">SSPD-1 represents a major milestone in a project that has been underway for more than a decade, garnering international attention as a tangible and high-profile step forward for a technology being pursued by multiple nations. It was launched on January 3, 2023, aboard a Momentus Vigoride spacecraft as part of the Caltech Space Solar Power Project (SSPP), led by professors Harry Atwater, Ali Hajimiri, and Sergio Pellegrino. It consists of three main experiments, each testing a different technology:</p><ul><li data-block-key="49f8f">DOLCE (Deployable on-Orbit ultraLight Composite Experiment): a structure measuring 1.8 meters by 1.8 meters that demonstrates the novel architecture, packaging scheme, and deployment mechanisms of the scalable modular spacecraft that will eventually make up a kilometer-scale constellation to serve as a power station.</li><li data-block-key="enptn">ALBA: a collection of 32 different types of photovoltaic (PV) cells to enable an assessment of the types of cells that can withstand punishing space environments.</li><li data-block-key="1dccu">MAPLE (Microwave Array for Power-transfer Low-orbit Experiment): an array of flexible, lightweight microwave-power transmitters based on custom integrated circuits with precise timing control to focus power selectively on two different receivers to demonstrate wireless power transmission at distance in space.</li></ul><p data-block-key="14l8t">"It's not that we don't have solar panels in space already. Solar panels are used to power the International Space Station, for example," says Atwater, Otis Booth Leadership Chair of Division of Engineering and Applied Science; Howard Hughes Professor of Applied Physics and Materials Science; director of the Liquid Sunlight Alliance; and one of the principal investigators of SSPP. "But to launch and deploy large enough arrays to provide meaningful power to Earth, SSPP has to design and create solar power energy transfer systems that are ultra-lightweight, cheap, flexible, and deployable."</p><p data-block-key="25ocb"><b>DOLCE: Deploying the Structure</b></p><p data-block-key="b7udp">Though all of the experiments aboard SSPD-1 were ultimately successful, not everything went according to plan. For the scientists and engineers leading this effort, however, that was exactly the point. The authentic test environment for SSPD-1 provided an opportunity to evaluate each of the components and the insights gleaned will have a profound impact on future space solar power array designs.</p><embed embedtype="media" url="https://youtu.be/tvPUlq-adWI?si=7qcFI2QM5bFPqizZ"/><p data-block-key="65mt0">For example, during the deployment of DOLCE—which was intended to be a three- to four-day process—one of the wires connecting the diagonal booms to the corners of the structure, which allowed it to unfurl, became snagged. This stalled the deployment and damaged the connection between one of the booms and the structure.</p><p data-block-key="459n2">With the clock ticking, the team used cameras on DOLCE as well as a full-scale working model of DOLCE in Pellegrino's lab to identify and try to solve the problem. They established that the damaged system would deploy better when warmed directly by the Sun and also by solar energy reflected off Earth.</p><p data-block-key="9tnlu">Once the diagonal booms had been deployed and the structure was fully uncoiled, a new complication arose: Part of the structure became jammed under the deployment mechanism, something that had never been seen in laboratory testing. Using images from the DOLCE cameras, the team was able to reproduce this kind of jamming in the lab and developed a strategy to fix it. Ultimately, Pellegrino and his team completed the deployment through a motion of DOLCE's actuators that vibrated the whole structure and worked the jam free. Lessons from the experience, Pellegrino says, will inform the next deployment mechanism.</p><p data-block-key="4dtc7">"The space test has demonstrated the robustness of the basic concept, which has allowed us to achieve a successful deployment in spite of two anomalies," says Pellegrino, Joyce and Kent Kresa Professor of Aerospace and Civil Engineering and co-director of SSPP. "The troubleshooting process has given us many new insights and has sharply focused us on the connection between our modular structure and the diagonal booms. We have developed new ways to counter the effects of self-weight in ultralight deployable structures."</p><p data-block-key="1173t"><b>ALBA: Harvesting Solar Energy</b></p><p data-block-key="ajsf8">Meanwhile, the photovoltaic performance of three entirely new classes of ultralight research-grade solar cells, none of which had ever been tested in orbit before, were measured over the course of more than 240 days of operation by the ALBA team, led by Atwater. Some of the solar cells were custom-fabricated using facilities in the SSPP labs and the Kavli Nanoscience Institute (KNI) at Caltech, which gave the team a reliable and fast way to get small cutting-edge devices quickly ready for flight. In future work, the team plans to test large-area cells made using highly scalable inexpensive manufacturing methods that can dramatically reduce both the mass and the cost of these space solar cells.</p><p data-block-key="aoe9v">Space solar cells presently available commercially are typically 100 times more expensive than the solar cells and modules widely deployed on Earth. This is because their manufacture employs an expensive step called epitaxial growth, in which crystalline films are grown in a specific orientation on a substrate. The SSPP solar cell team achieved low-cost nonepitaxial space cells by using cheap and scalable production processes like those used to make today's silicon solar cells. These processes employ high-performance compound semiconductor materials such as gallium arsenide that are typically used to make high-efficiency space cells today.</p><p data-block-key="2nba4">The team also tested perovskite cells, which have captured the attention of solar manufacturers because they are cheap and flexible, and luminescent solar concentrators with the potential to be deployed in large flexible polymer sheets.</p><p data-block-key="1ltt7">Over ALBA's lifespan, the team collected enough data to be able to observe changes in the operation of individual cells in response to space weather events like solar flares and geomagnetic activity. They found, for example, tremendous variability in the performance of the perovskite cells, whereas the low-cost gallium arsenide cells consistently performed well overall.</p><p data-block-key="a3gdc">"SSPP gave us a unique opportunity to take solar cells directly from the lab at Caltech into orbit, accelerating the in-space testing that would normally have taken years to be done. This kind of approach has dramatically shortened the innovation-cycle time for space solar technology," says Atwater.</p><p data-block-key="72mcq"><b>MAPLE: Wireless Power Transfer in Space</b></p><p data-block-key="7865o">Finally, as announced in June, MAPLE demonstrated its ability to transmit power wirelessly in space and to direct a beam to Earth—a first in the field. MAPLE experiments continued for eight months after the initial demonstrations, and in this subsequent work, the team pushed MAPLE to its limits to expose and understand its potential weaknesses so that lessons learned could be applied to future design.</p><embed alt="MAPLE" embedtype="image" format="RightAlignMedium" id="10320"/><p data-block-key="b1jj1">The team compared the performance of the array early in the mission with its performance at the end of the mission, when MAPLE was intentionally stressed. A drop in the total transmitted power was observed. Back in the lab on Earth, the group reproduced the power drop, attributing it to the degradation of a few individual transmitting elements in the array as well as some complex electrical–thermal interactions in the system.</p><p data-block-key="svo0">"These observations have already led to revisions in the design of various elements of MAPLE to maximize its performance over extended periods of time," says Hajimiri, Bren Professor of Electrical Engineering and Medical Engineering and co-director of SSPP. "Testing in space with SSPD-1 has given us more visibility into our blind spots and more confidence in our abilities."</p><p data-block-key="21uit"><b>SSPP: Moving Forward</b></p><p data-block-key="5698p">SSPP began after philanthropist Donald Bren, chairman of Irvine Company and a life member of the Caltech community, first learned about the potential for space-based solar energy manufacturing as a young man in an article in <i>Popular Science</i> magazine. Intrigued by the potential for space solar power, Bren approached Caltech's then-president Jean-Lou Chameau in 2011 to discuss the creation of a space-based solar power research project. In the years to follow, Bren and his wife, Brigitte Bren, a Caltech trustee, agreed to make a series of donations (yielding a total commitment of over $100 million) through the Donald Bren Foundation to fund the project and to endow a number of Caltech professorships.</p><p data-block-key="3lkm">"The hard work and dedication of the brilliant scientists at Caltech have advanced our dream of providing the world with abundant, reliable, and affordable power for the benefit of all humankind," Donald Bren says.</p><p data-block-key="82s8p">In addition to the support received from the Brens, Northrop Grumman Corporation provided Caltech with $12.5 million between 2014 and 2017 through a sponsored research agreement that aided technology development and advanced the project's science.</p><p data-block-key="a2a1">With SSPD-1 winding down its mission, the testbed stopped communications with Earth on November 11. The Vigoride-5 vehicle that hosted SSPD-1 will remain in orbit to support continued testing and demonstration of the vehicle's Microwave Electrothermal Thruster engines that use distilled water as a propellant. It will ultimately deorbit and disintegrate in Earth's atmosphere.</p><p data-block-key="b9lcs">Meanwhile, the SSPP team continues work in the lab, studying the feedback from SSPD-1 to identify the next set of fundamental research challenges for the project to tackle.</p><p data-block-key="ahhsn"><i><sub>Top image: The DOLCE structure completely deployed, over the Canadian Arctic, on September 29, 2023. DOLCE structure's TRAC longerons and battens are clearly visible above the Arctic ice. The fiberglass batten connectors are shining under the Sun (right part).</sub></i></p>Aided by AI, New Catheter Design Prevents Bacterial Infections2024-01-05T16:47:00+00:002024-01-31T17:20:09.963602+00:00Lori Dajoseldajose@caltech.eduhttps://www.caltech.edu/about/news/aided-by-ai-new-catheter-design-prevents-bacterial-infections<p data-block-key="0dcm0">Bacteria are remarkably good swimmers—a trait that can be detrimental to human health. One of the most common bacterial infections in a healthcare setting comes from bacteria entering the body through catheters, thin tubes inserted in the urinary tract. Though catheters are designed to draw fluids out of a patient, bacteria are able to propel themselves upstream and into the body via catheter tubes using a unique swimming motion, causing $300 million of catheter-associated urinary infections in the U.S. annually.</p><p data-block-key="1u0kt">Now, an interdisciplinary project at Caltech has designed a new type of catheter tube that impedes the upstream mobility of bacteria, without the need for antibiotics or other chemical antimicrobial methods. With the new design, which was optimized by novel artificial intelligence (AI) technology, the number of bacteria that are able to swim upstream in laboratory experiments was reduced 100-fold.</p><p data-block-key="2aq5d">A paper describing the study appears in the journal <i>Science Advances</i> on January 3. The work was a collaboration between the laboratories of <a href="https://www.eas.caltech.edu/people/daraio">Chiara Daraio</a>, G. Bradford Jones Professor of Mechanical Engineering and Applied Physics and Heritage Medical Research Institute Investigator; <a href="https://www.bbe.caltech.edu/people/paul-w-sternberg">Paul Sternberg</a>, Bren Professor of Biology; <a href="https://cce.caltech.edu/people/john-f-brady?back_url=%2Fpeople%3Fcategory%3D%26category%3D3%26search%3D%26submit%3DSearch%2B%25C2%25A0%2B%253E">John Brady</a>, Chevron Professor of Chemical Engineering and Mechanical Engineering; and <a href="https://www.eas.caltech.edu/people/anima">Anima Anandkumar</a>, Bren Professor of Computing and Mathematical Sciences.</p><p data-block-key="bdggi">In catheter tubes, fluid exhibits a so-called Poiseuille flow, an effect where fluid movement is faster in the center but slow near the wall, similar to the flow in a river's current, where the velocity of the water varies from fast in the center to slow near the banks. Bacteria, as self-propelling organisms, exhibit a unique "two-step forward along the wall, one-step back in the middle" motion that produces their forward progress in tubular structures. Researchers in the Brady lab had previously modeled this phenomenon.</p><p data-block-key="dmhgq">"One day, I shared this intriguing phenomenon with Chiara Daraio, framing it simply as a 'cool thing,' and her response shifted the conversation toward a practical application," says Tingtao Edmond Zhou, postdoctoral scholar in chemical engineering and a co-first author of the study. "Chiara's research often plays with all kinds of interesting geometries, and she suggested tackling this problem with simple geometries."</p><p data-block-key="88rla">Following that suggestion, the team designed tubes with triangular protrusions, like shark fins, along the inside of the tube's walls. Simulations yielded promising results: These geometric structures effectively redirected bacterial movement, propelling them toward the center of the tube where the faster flow pushed them back downstream. The triangles' fin-like curvature also generated vortices that further disrupted bacterial progress.</p><p data-block-key="7ksil"></p><embed alt="Gray curved triangles, angled to point right, at the top and bottom. Pill-shaped bacteria traveling left are caught and sent to the right." embedtype="image" format="MiddleAlignMedium" id="10303"/><p data-block-key="5r4vm"></p><p data-block-key="6e4ta">Zhou and his collaborators aimed to verify the design experimentally but needed additional biology expertise. For that, Zhou reached out to Olivia Xuan Wan, a postdoctoral scholar in the Sternberg laboratory.</p><p data-block-key="6j99v">"I study nematode navigation, and this project resonated deeply with my specialized interest in motion trajectories," says Wan, who is also a co-first author on the new paper. For years, the Sternberg laboratory has conducted research into the navigation mechanisms of the nematode <i>Caenorhabditis elegans</i>, a rice grain–sized soil organism commonly studied in research labs and thus had many of the tools to observe and analyze the movements of microscopic organisms.</p><p data-block-key="7rfm8">The team quickly transitioned from theoretical modeling to practical experimentation, using 3D printed catheter tubes and high-speed cameras to monitor bacterial progress. The tubes with triangular inclusions resulted in a reduction of upstream bacterial movement by two orders of magnitude (a 100-fold decrease).</p><p data-block-key="6fh62">The team then continued simulations to determine the most effective triangular obstacle shape to impede bacteria's upstream swimming. They then fabricated microfluidic channels analogous to common catheter tubes with the optimized triangular designs to observe the movement of <i>E. coli</i> bacteria under various flow conditions. The observed trajectories of the <i>E. coli</i> within these microfluidic environments aligned almost perfectly with the simulated predictions.</p><p data-block-key="feta6">The collaboration grew as the researchers aimed to continue improving the geometric tube design. Artificial intelligence experts in the Anandkumar laboratory provided the project with cutting-edge AI methods called neural operators. This technology was able to accelerate the catheter design optimization computations so they required not days but minutes. The resulting model proposed tweaks to the geometric design, further optimizing the triangle shapes to prevent even more bacteria from swimming upstream. The final design enhanced the efficacy of the initial triangular shapes by an additional 5 percent in simulations.</p><p data-block-key="3l3ie">"A collaborative spirit defines Caltech," says Sternberg. "Caltech people help each other. This endeavor was truly an interdisciplinary journey, weaving together diverse fields of study."</p><p data-block-key="582oa">"Our journey from theory to simulation, experiment, and, finally, to real-time monitoring within these microfluidic landscapes is a compelling demonstration of how theoretical concepts can be brought to life, offering tangible solutions to real-world challenges," says Zhou. "I'm very lucky to be at Caltech with so many talented colleagues."</p><p data-block-key="5vtki">The paper is titled <a href="https://www.science.org/doi/10.1126/sciadv.adj1741">"AI-aided geometric design of anti-infection catheters."</a> Zhou and Wan are the study's co-first authors. In addition to Anandkumar, Brady, Sternberg, and Daraio, additional Caltech co-authors are graduate student Zongyi Li and alum Zhiwei Peng (PhD '22). Daniel Zhengyu Huang of Peking University in Beijing, formerly a postdoctoral scholar in the laboratory of Tapio Schneider, the Theodore Y. Wu Professor of Environmental Science and Engineering and JPL senior research scientist, is also a co-author. Funding was provided by the Donna and Benjamin M. Rosen Bioengineering Center, the Heritage Medical Research Institute, the National Science Foundation, the Schmidt Futures program, the PIMCO Future Leaders Scholarship, the Amazon AI4Science Fellowship, and Bren Professorships. Stenberg and Anandkumar are affiliated faculty members with the <a href="https://neuroscience.caltech.edu/">Tianqiao and Chrissy Chen Institute for Neuroscience at Caltech</a>.</p>Theodore Y. Wu, 1924–20232023-12-21T17:33:00+00:002024-01-02T21:45:53.754322+00:00Emily Velascoevelasco@caltech.eduhttps://www.caltech.edu/about/news/theodore-y-wu-19242023<p data-block-key="6mu4x">Theodore Y. Wu (PhD '52), professor of engineering science, emeritus, passed away on December 16. He was 99 years old.</p><p data-block-key="dp519"></p><embed alt="A photo of Theodore Wu. He wears a shirt and tie and blazer." embedtype="image" format="RightAlignSmall" id="10297"/><p data-block-key="68gdk"></p><p data-block-key="c1agu">Wu was born in a village in Changzhou, China, in 1924, and moved around the country with his family as his father worked for the government on a railroad nationalization program. The Japanese occupation during WWII caused hardship for many in China, including Wu's family, but the sight of Japanese aircraft is said to have inspired Wu's interest in aeronautics.</p><p data-block-key="246au">He earned his bachelor's degree in aeronautics from Chiao-Tung University, Shanghai, China, in 1946 and his master's degree, also in aeronautics, at Iowa State University in 1948. At Caltech, he studied under Paco Lagerstrom, professor of applied mathematics, and earned his PhD in aeronautics and mathematics in 1952. He was hired as a research fellow at the Institute upon graduation and became an assistant professor in applied mechanics in 1955. He was made full professor in 1961 and continued working in that position in Engineering Science until his retirement in 1996.</p><p data-block-key="10ps9"></p><embed alt="A man wearing a shirt and tie appears at the center of this black and white photo. He leans on a table covered in papers and surrounded by students who are listening to him as he talks." embedtype="image" format="MiddleAlignLarge" id="10296"/><p data-block-key="dgg8e"></p><p data-block-key="bgbkf">Wu's research was interdisciplinary, combining aspects of aeronautics, mathematics, and fluid physics, and it was wide ranging, covering topics that included the physics of jets and wakes, the energy of ocean currents and wind, ocean waves, the flight of birds and insects, how fish swim, and the locomotion of microorganisms.</p><p data-block-key="bs2c4">Among the awards and honors Wu received are the Caltech Distinguished Teaching Award, a John Simon Guggenheim Fellowship, an Australian CSIRO and Universities Fellowship, the Japan Society for the Promotion of Science Fellowship, the Fluid Mechanics Prize, and the von Kármán Medal. His contributions were recognized with lifetime achievement awards from the Chinese–American Faculty Association of Southern California in 1993; the Chinese Engineers and Scientists Association of Southern California in 1995; the North American Chiao Tung University Alumni Association (CTUAA) in 2000; and the CTUAA of Southern California in 2006.</p><p data-block-key="bahim">He was a member of the U.S. National Academy of Engineering, the Academia Sinica (Taiwan), a foreign member of the Chinese Academy of Sciences, an honorary fellow of the Institute of Mechanics, and a fellow of the American Physical Society. Other memberships include Chinese Engineers and Scientists Association of Southern California (CESASC); and the Phi Tau Phi Scholastic Honor Society.</p><p data-block-key="eh4ci">Wu was pre-deceased by his wife Dr. Chin-Hua Wu (2015). He is survived by his children Fonda B. Wu and his wife Sandy Chang, and Melba B. Wu and husband Michael C. Bush, and grandchildren Martin Bush, Matthew Bush and his wife Lisa Gano, and great-grandson Maceo Bush.</p><p data-block-key="a9vi4">In lieu of flowers, the family welcomes contributions to the <a href="https://caltech.imodules.com/wugradfellowshipfund">Theodore Y. Wu Graduate Fellowship</a>. Memorial gifts may be made online <a href="https://caltech.imodules.com/wugradfellowshipfund">here</a> or checks may be mailed to Theodore Y. Wu Graduate Fellowship c/o Caltech, Advancement and Alumni Relations, PO Box 102963, Pasadena, CA. 91189-2963.</p><p data-block-key="avq62">A full obituary will be posted at a later date.</p>